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Sample records for action potential evoked

  1. An indirect component in the evoked compound action potential of the vagal nerve

    Science.gov (United States)

    Ordelman, Simone C. M. A.; Kornet, Lilian; Cornelussen, Richard; Buschman, Hendrik P. J.; Veltink, Peter H.

    2010-12-01

    The vagal nerve plays a vital role in the regulation of the cardiovascular system. It not only regulates the heart but also sends sensory information from the heart back to the brain. We hypothesize that the evoked vagal nerve compound action potential contains components that are indirect via the brain stem or coming via the neural network on the heart. In an experimental study of 15 pigs, we identified four components in the evoked compound action potentials. The fourth component was found to be an indirect component, which came from the periphery. The latency of the indirect component increased when heart rate and contractility were decreased by burst stimulation (P = 0.01; n = 7). When heart rate and contractility were increased by dobutamine administration, the latency of the indirect component decreased (P = 0.01; n = 9). This showed that the latency of the indirect component of the evoked compound action potentials may relate to the state of the cardiovascular system.

  2. An indirect component in the evoked compound action potential of the vagal nerve

    NARCIS (Netherlands)

    Ordelman, Simone Cornelia Maria Anna; Kornet, Lilian; Cornelussen, Richard; Buschman, H.P.J.; Veltink, Petrus H.

    2010-01-01

    The vagal nerve plays a vital role in the regulation of the cardiovascular system. It not only regulates the heart but also sends sensory information from the heart back to the brain. We hypothesize that the evoked vagal nerve compound action potential contains components that are indirect via the

  3. Direct detection of a single evoked action potential with MRS in Lumbricus terrestris.

    Science.gov (United States)

    Poplawsky, Alexander J; Dingledine, Raymond; Hu, Xiaoping P

    2012-01-01

    Functional MRI (fMRI) measures neural activity indirectly by detecting the signal change associated with the hemodynamic response following brain activation. In order to alleviate the temporal and spatial specificity problems associated with fMRI, a number of attempts have been made to detect neural magnetic fields (NMFs) with MRI directly, but have thus far provided conflicting results. In this study, we used MR to detect axonal NMFs in the median giant fiber of the earthworm, Lumbricus terrestris, by examining the free induction decay (FID) with a sampling interval of 0.32 ms. The earthworm nerve cords were isolated from the vasculature and stimulated at the threshold of action potential generation. FIDs were acquired shortly after the stimulation, and simultaneous field potential recordings identified the presence or absence of single evoked action potentials. FIDs acquired when the stimulus did not evoke an action potential were summed as background. The phase of the background-subtracted FID exhibited a systematic change, with a peak phase difference of (-1.2 ± 0.3) × 10(-5) radians occurring at a time corresponding to the timing of the action potential. In addition, we calculated the possible changes in the FID magnitude and phase caused by a simulated action potential using a volume conductor model. The measured phase difference matched the theoretical prediction well in both amplitude and temporal characteristics. This study provides the first evidence for the direct detection of a magnetic field from an evoked action potential using MR. Copyright © 2011 John Wiley & Sons, Ltd.

  4. [The central action of botulinum toxin type A assessed by brain auditory and somatosensory evoked potentials].

    Science.gov (United States)

    Sławek, Jarosław; Recławowicz, Daniel

    2004-01-01

    Botulinum toxin type A (BTX-A) acts as a neuromuscular blocker in the release of acetylcholine. Nevertheless, some clinical effects and side effects are difficult to explain only due to the peripheral mode of action. The aim of the study was to assess the central effects of BTX-A by measuring the two modalities of evoked potentials (somatosensory and brain-stem auditory). In 23 patients (13 females, 10 males, mean age of 46, range of 25-71) with idiopathic cervical dystonia (never treated with BTX-A) brainstem auditory evoked responses (BAER) and somatosensory evoked potentials from upper extremities (SEP) were performed before and 4-6 weeks after BTX-A administration. BTX-A (Botox in 14 patients, Dysport in 9 patients) was injected into neck muscles: sternocleidomastoideus, splenius capitis, trapezius and levator scapulae. The authors did not find any statistically significant differences in basic parameters (latency and interlatency of I, III, V in BAER and N9, N13, N20 and P25 responses in SEP) before and after BTX-A administration. It seems that BTX-A does not have any direct central effect or the methods are not sensitive enough to detect them. Remote (anatomically distant) clinical effects seen by other authors or side effects may be explained by indirect mechanism due to deafferentation of stimuli from muscle spindles after BTX-A injection and thus modifying the central loops of reflexes or due to unpredictable hematogenous spread of BTX-A to distant muscles.

  5. Changes in evoked potentials and amino acid content during fluorocitrate action studied in rat hippocampal cortex.

    Science.gov (United States)

    Berg-Johnsen, J; Paulsen, R E; Fonnum, F; Langmoen, I A

    1993-01-01

    Fluorocitrate inhibits the glial tricarboxylic acid cycle and thereby the synthesis of glutamine, which is the main precursor for transmitter glutamate. We investigated the possibility that there is a functional correlate to fluorocitrate action by recording evoked field potentials in rat hippocampal slices. The excitatory postsynaptic potential (field-EPSP) was markedly depressed after 7-8 h of fluorocitrate action. The population spike was also reduced, but a major part of the reduction may be the result of weaker synaptic activation rather than reduced excitability of the postsynaptic cells. The activity of thin unmyelinated fibres was only slightly affected. Preceding the changes in the field-EPSP there was a decrease in the glutamine content in the fluorocitrate treated slices relative to controls. Only a small decrease in tissue glutamate was seen concomitantly with the synaptic failure, probably because the transmitter pool of glutamate in those fibres stimulated makes little contribution to the total tissue glutamate.

  6. Analysis of electrically evoked compound action potential of the auditory nerve in children with bilateral cochlear implants.

    Science.gov (United States)

    Caldas, Fernanda Ferreira; Cardoso, Carolina Costa; Barreto, Monique Antunes de Souza Chelminski; Teixeira, Marina Santos; Hilgenberg, Anacléia Melo da Silva; Serra, Lucieny Silva Martins; Bahmad Junior, Fayez

    2016-01-01

    The cochlear implant device has the capacity to measure the electrically evoked compound action potential of the auditory nerve. The neural response telemetry is used in order to measure the electrically evoked compound action potential of the auditory nerve. To analyze the electrically evoked compound action potential, through the neural response telemetry, in children with bilateral cochlear implants. This is an analytical, prospective, longitudinal, historical cohort study. Six children, aged 1-4 years, with bilateral cochlear implant were assessed at five different intervals during their first year of cochlear implant use. There were significant differences in follow-up time (p=0.0082) and electrode position (p=0.0019) in the T-NRT measure. There was a significant difference in the interaction between time of follow-up and electrode position (p=0.0143) when measuring the N1-P1 wave amplitude between the three electrodes at each time of follow-up. The electrically evoked compound action potential measurement using neural response telemetry in children with bilateral cochlear implants during the first year of follow-up was effective in demonstrating the synchronized bilateral development of the peripheral auditory pathways in the studied population. Copyright © 2015 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

  7. Somatosensory evoked potentials for the diagnosis of proximal sensory median neuropathy with preserved distal sensory action potential.

    Science.gov (United States)

    Merle, P E; Joan, N; Varnet, O; Dupuy-Sonntag, D; Perin, B; Macron, J M

    2003-12-01

    A 33 year-old-man with paresthesia in first three fingers of the right hand after minor trauma of the arm was examined electrophysiologically. The proximal sensory median neuropathy was isolated which it is unusual in traumatic lesion. Motor and distal sensory conduction studies were normal but sensory evoked potentials (SEPs) were abnormal by right median nerve stimulation at the wrist level with decrease in amplitude of peripheral potential at the Erb's point, the cervical and contralateral parietal levels. This pattern, preserved distal sensory action potential and abnormal peripheral SEPs were suggesting the presence of proximal sensory block conduction without wallerian degeneration. The recovery was complete and fast in correlation with the absence of axonopathy.

  8. Recovery time of motor evoked potentials following lengthening and shortening muscle action in the tibialis anterior

    NARCIS (Netherlands)

    Tallent, J.; Goodall, S.; Hortobagyi, T.; Gibson, A. St Clair; French, D. N.; Howatson, G.

    Motor evoked potentials (MEP) at rest remain facilitated following an isometric muscle contraction. Because the pre-synaptic and post-synaptic control of shortening (SHO) and lengthening (LEN) contractions differs, the possibility exists that the recovery of the MEP is also task specific. The time

  9. Electrically evoked compound action potentials artefact rejection by independent component analysis: procedure automation.

    Science.gov (United States)

    Akhoun, Idrick; McKay, Colette; El-Deredy, Wael

    2015-01-15

    Independent-components-analysis (ICA) successfully separated electrically-evoked compound action potentials (ECAPs) from the stimulation artefact and noise (ECAP-ICA, Akhoun et al., 2013). This paper shows how to automate the ECAP-ICA artefact cancellation process. Raw-ECAPs without artefact rejection were consecutively recorded for each stimulation condition from at least 8 intra-cochlear electrodes. Firstly, amplifier-saturated recordings were discarded, and the data from different stimulus conditions (different current-levels) were concatenated temporally. The key aspect of the automation procedure was the sequential deductive source categorisation after ICA was applied with a restriction to 4 sources. The stereotypical aspect of the 4 sources enables their automatic classification as two artefact components, a noise and the sought ECAP based on theoretical and empirical considerations. The automatic procedure was tested using 8 cochlear implant (CI) users and one to four stimulus electrodes. The artefact and noise sources were successively identified and discarded, leaving the ECAP as the remaining source. The automated ECAP-ICA procedure successfully extracted the correct ECAPs compared to standard clinical forward masking paradigm in 22 out of 26 cases. ECAP-ICA does not require extracting the ECAP from a combination of distinct buffers as it is the case with regular methods. It is an alternative that does not have the possible bias of traditional artefact rejections such as alternate-polarity or forward-masking paradigms. The ECAP-ICA procedure bears clinical relevance, for example as the artefact rejection sub-module of automated ECAP-threshold detection techniques, which are common features of CI clinical fitting software. Copyright © 2014. Published by Elsevier B.V.

  10. Impedance and electrically evoked compound action potential (ECAP drop within 24 hours after cochlear implantation.

    Directory of Open Access Journals (Sweden)

    Joshua Kuang-Chao Chen

    Full Text Available Previous animal study revealed that post-implantation electrical detection levels significantly declined within days. The impact of cochlear implant (CI insertion on human auditory pathway in terms of impedance and electrically evoked compound action potential (ECAP variation within hours after surgery remains unclear, since at this time frequency mapping can only commence weeks after implantation due to factors associated with wound conditions. The study presented our experiences with regards to initial switch-on within 24 hours, and thus the findings about the milieus inside cochlea within the first few hours after cochlear implantation in terms of impedance/ECAP fluctuations. The charts of fifty-four subjects with profound hearing impairment were studied. A minimal invasive approach was used for cochlear implantation, characterized by a small skin incision (≈ 2.5 cm and soft techniques for cochleostomy. Impedance/ECAP was measured intro-operatively and within 24 hours post-operatively. Initial mapping within 24 hours post-operatively was performed in all patients without major complications. Impedance/ECAP became significantly lower measured within 24 hours post-operatively as compared with intra-operatively (p<0.001. There were no differences between pre-operative and post-operative threshold for air-conduction hearing. A significant drop of impedance/ECAP in one day after cochlear implantation was revealed for the first time in human beings. Mechanisms could be related to the restoration of neuronal sensitivity to the electrical stimulation, and/or the interaction between the matrix enveloping the electrodes and the electrical stimulation of the initial switch-on. Less wound pain/swelling and soft techniques both contributed to the success of immediate initial mapping, which implied a stable micro-environment inside the cochlea despite electrodes insertion. Our research invites further studies to correlate initial impedance/ECAP changes

  11. International Evoked Potentials Symposium

    CERN Document Server

    1980-01-01

    The past decade has seen great progress in the measurement of evoked potentials in man; a steady increase in our understanding of their charac­ teristics, their origins and their usefulness; and a growing application in the field of clinical diagnosis. The topic is a truly multidisciplinary one. Important research contributions have been made by workers of many different backgrounds and clinical applications span the specialities. This book represents a revised and updated version of the work originally presented at the international evoked potential symposium held in Nottingham 4-6 1978. The Nottingham Symposium provided a forum for a state-of-the-art discussion amongst workers from many different disciplines and from many different countries. For each major topic in the field an expert review set the scene for discussion of current research presentations. This format is retained in the book: the chapters in Part A provide the context in which the research presented in Part B is set. The task of selecting m...

  12. The effect of shoulder position on motor evoked and maximal muscle compound action potentials of the biceps brachii.

    Science.gov (United States)

    Collins, Brandon W; Button, Duane C

    2018-02-05

    The purpose of the study was to assess the effect of shoulder position, 0° versus 90° shoulder flexion, on stimulation intensity and maximal muscle compound action potentials (M max ) and motor evoked potentials (MEP) of the biceps brachii during both rest and 10% maximum voluntary contraction (MVC). Nine participants completed two experimental sessions with four conditions. During each condition, transcranial magnetic (TMS) and Erb's point stimulation were used to elicit MEPs and M max , respectively. During rest, the TMS intensity to elicit a MEP response (pshoulder-position and state-dependent, whereas MEP and M max amplitudes were only shoulder position-dependent. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Action potential-evoked calcium release is impaired in single skeletal muscle fibers from heart failure patients.

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    Marino DiFranco

    Full Text Available Exercise intolerance in chronic heart failure (HF has been attributed to abnormalities of the skeletal muscles. Muscle function depends on intact excitation-contraction coupling (ECC, but ECC studies in HF models have been inconclusive, due to deficiencies in the animal models and tools used to measure calcium (Ca2+ release, mandating investigations in skeletal muscle from HF patients. The purpose of this study was to test the hypothesis that Ca2+ release is significantly impaired in the skeletal muscle of HF patients in whom exercise capacity is severely diminished compared to age-matched healthy volunteers.Using state-of-the-art electrophysiological and optical techniques in single muscle fibers from biopsies of the locomotive vastus lateralis muscle, we measured the action potential (AP-evoked Ca2+ release in 4 HF patients and 4 age-matched healthy controls. The mean peak Ca2+ release flux in fibers obtained from HF patients (10±1.2 µM/ms was markedly (2.6-fold and significantly (p<0.05 smaller than in fibers from healthy volunteers (28±3.3 µM/ms. This impairment in AP-evoked Ca2+ release was ubiquitous and was not explained by differences in the excitability mechanisms since single APs were indistinguishable between HF patients and healthy volunteers.These findings prove the feasibility of performing electrophysiological experiments in single fibers from human skeletal muscle, and offer a new approach for investigations of myopathies due to HF and other diseases. Importantly, we have demonstrated that one step in the ECC process, AP-evoked Ca2+ release, is impaired in single muscle fibers in HF patients.

  14. Spine Calcium Transients Induced by Synaptically-Evoked Action Potentials Can Predict Synapse Location and Establish Synaptic Democracy

    Science.gov (United States)

    Meredith, Rhiannon M.; van Ooyen, Arjen

    2012-01-01

    CA1 pyramidal neurons receive hundreds of synaptic inputs at different distances from the soma. Distance-dependent synaptic scaling enables distal and proximal synapses to influence the somatic membrane equally, a phenomenon called “synaptic democracy”. How this is established is unclear. The backpropagating action potential (BAP) is hypothesised to provide distance-dependent information to synapses, allowing synaptic strengths to scale accordingly. Experimental measurements show that a BAP evoked by current injection at the soma causes calcium currents in the apical shaft whose amplitudes decay with distance from the soma. However, in vivo action potentials are not induced by somatic current injection but by synaptic inputs along the dendrites, which creates a different excitable state of the dendrites. Due to technical limitations, it is not possible to study experimentally whether distance information can also be provided by synaptically-evoked BAPs. Therefore we adapted a realistic morphological and electrophysiological model to measure BAP-induced voltage and calcium signals in spines after Schaffer collateral synapse stimulation. We show that peak calcium concentration is highly correlated with soma-synapse distance under a number of physiologically-realistic suprathreshold stimulation regimes and for a range of dendritic morphologies. Peak calcium levels also predicted the attenuation of the EPSP across the dendritic tree. Furthermore, we show that peak calcium can be used to set up a synaptic democracy in a homeostatic manner, whereby synapses regulate their synaptic strength on the basis of the difference between peak calcium and a uniform target value. We conclude that information derived from synaptically-generated BAPs can indicate synapse location and can subsequently be utilised to implement a synaptic democracy. PMID:22719238

  15. Potassium conductances mediate bidirectional state-dependent modulation of action potential evoked dendritic calcium signals in dentate gyrus granule cells

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    János Brunner

    2014-03-01

    Full Text Available Backpropagating action potentials (bAPs and local calcium signals that they trigger are fundamental for dendritic functions. Here we addressed the question what extent the changes of local dendritic membrane properties can contribute to the shaping of the coupling between dendritic action potentials and the local calcium responses. Using a combination of in vitro electrophysiological and confocal imaging techniques we found that activation of dendritic GIRK channels via mGlu2 or GABAB receptors enhanced the bAP¬-triggered calcium signals in the dendrites of dentate gyrus granule cells (GCs. The enhancement of calcium signals was significant only in those dendritic regions, where these receptors are predominantly expressed. Similarly to GIRK channel activation, somatic hyperpolarization by DC current injection (from -64 mV to -77 mV, significantly increased bAP-associated calcium signals in the proximal dendrites. The hyperpolarization was associated with a decrease in the input resistance due to the rectification of the membrane potential of GCs. The effect of hyperpolarization on the calcium signals was maintained when T-type calcium currents were blocked but it decreased when GIRK channels were inhibited. Simultaneous dual somato-dendritic recordings from GCs showed that somatic hyperpolarization accelerated the repolarization phase of dendritic bAP in the proximal region whereas the rising phase and peak amplitude was not affected. We hypothesize that the larger driving force for calcium ions during the faster repolarization can contribute to the increasing in calcium signals. Employment of previously recorded dendritic bAP waveforms from hyperpolarized membrane potential as voltage command evoked larger calcium currents in nucleated patches compared to bAP waveform from the same recording at depolarized membrane potential. Furthermore, addition of native, high-voltage activated, inactivating potassium conductance by somatic dynamic clamp

  16. Normative findings of electrically evoked compound action potential measurements using the neural response telemetry of the Nucleus CI24M cochlear implant system.

    NARCIS (Netherlands)

    Cafarelli-Dees, D.; Dillier, N.; Lai, W.K.; Wallenberg, E. von; Dijk, B. van; Akdas, F.; Aksit, M.; Batman, C.; Beynon, A.J.; Burdo, S.; Chanal, J.M.; Collet, L.; Conway, M.; Coudert, C.; Craddock, L.; Cullington, H.; Deggouj, N.; Fraysse, B.; Grabel, S.; Kiefer, J.; Kiss, J.G.; Lenarz, T.; Mair, A.; Maune, S.; Muller-Deile, J.; Piron, J.P.; Razza, S.; Tasche, C.; Thai-Van, H.; Toth, F.; Truy, E.; Uziel, A.; Smoorenburg, G.F.

    2005-01-01

    One hundred and forty-seven adult recipients of the Nucleus 24 cochlear implant system, from 13 different European countries, were tested using neural response telemetry to measure the electrically evoked compound action potential (ECAP), according to a standardised postoperative measurement

  17. Assessing the Electrode-Neuron Interface with the Electrically Evoked Compound Action Potential, Electrode Position, and Behavioral Thresholds.

    Science.gov (United States)

    DeVries, Lindsay; Scheperle, Rachel; Bierer, Julie Arenberg

    2016-06-01

    Variability in speech perception scores among cochlear implant listeners may largely reflect the variable efficacy of implant electrodes to convey stimulus information to the auditory nerve. In the present study, three metrics were applied to assess the quality of the electrode-neuron interface of individual cochlear implant channels: the electrically evoked compound action potential (ECAP), the estimation of electrode position using computerized tomography (CT), and behavioral thresholds using focused stimulation. The primary motivation of this approach is to evaluate the ECAP as a site-specific measure of the electrode-neuron interface in the context of two peripheral factors that likely contribute to degraded perception: large electrode-to-modiolus distance and reduced neural density. Ten unilaterally implanted adults with Advanced Bionics HiRes90k devices participated. ECAPs were elicited with monopolar stimulation within a forward-masking paradigm to construct channel interaction functions (CIF), behavioral thresholds were obtained with quadrupolar (sQP) stimulation, and data from imaging provided estimates of electrode-to-modiolus distance and scalar location (scala tympani (ST), intermediate, or scala vestibuli (SV)) for each electrode. The width of the ECAP CIF was positively correlated with electrode-to-modiolus distance; both of these measures were also influenced by scalar position. The ECAP peak amplitude was negatively correlated with behavioral thresholds. Moreover, subjects with low behavioral thresholds and large ECAP amplitudes, averaged across electrodes, tended to have higher speech perception scores. These results suggest a potential clinical role for the ECAP in the objective assessment of individual cochlear implant channels, with the potential to improve speech perception outcomes.

  18. Proprioceptive evoked potentials in man

    DEFF Research Database (Denmark)

    Arnfred, S; Chen, A C; Eder, Derek N

    2000-01-01

    , P190, and a single negative frontal Fz/N70 component. We conclude that a brisk change of a hand held load elicits a significant evoked potential (EP) unlike the electrical somato-sensory EP (SEP). The stimulus is perceived as applied force. For this reason we call it a proprioceptive EP (PEP...

  19. Evaluation of the Slope of Amplitude Growth Function Changes of the Electrically Evoked Action Potential in Three Months after Receiving the Device in Children with Cochlear Implant

    Directory of Open Access Journals (Sweden)

    Ali Reza Pourjavid

    2012-04-01

    Full Text Available Objective: In neural response telemetry, intracochlear electrodes stimulate the auditory nerve and record the neural responses. The electrical stimulation is sent to the auditory nerve by an electrode and the resulted response, called electrically evoked compound action potential, is recorded by an adjacent electrode. The most important clinical applications of this test are evaluation and monitoring the intra and postoperative responses of auditory nerve and help to primary setting of speech processor. The aim of this study was evaluating the potential's slope of amplitude growth function changes three monthes after receiving the devise in pediatric cochlear implant recipients. Materials & Methods: This longitudinal study evaluated the potentials' slope of amplitude growth function changes in four given electrodes in four sessions after receiving the devise by approximately one month's intervals in all of the children who implanted in Amir Alam and Hazrat-e-Rasoul hospitals in 2007, July to December. Friedman test was used to analyse the results. Results: Electrically evoked compound action potential's mean slope of each electrode was more in later sessions relative to first session, while there was significant difference between the 1st and the other electrodes’ responses in every session (P<0.05. Conclusion: The reliabiliy of the responses results in more assurance of clinician to fit the speech processor for along time. Better responses in apical electrodes may lead to develope an effective coding strategy.

  20. EVALUATING THE NMDA-GLUTAMATE RECEPTOR AS A SITE OF ACTION FOR TOLUENE USING PATTERN ELICITED VISUAL EVOKED POTENTIALS.

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    In vitro studies have demonstrated that toluene disrupts the function of NMDA-glutamate receptors, as well as other channels. This has led to the hypothesis that effects on NMDA receptor function may contribute to toluene neurotoxicity, CNS depression, and altered visual evoked ...

  1. Visual Evoked Potentials in Rett Syndrome

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    J. Gordon Millichap

    2015-11-01

    Full Text Available Investigators from the Boston Children's Hospital recorded pattern-reversal visual evoked potentials (VEPs in Mecp2 heterozygous female mice and in 34 girls with Rett syndrome (RTT.

  2. Characterization of Cochlear, Vestibular and Cochlear-Vestibular Electrically Evoked Compound Action Potentials in Patients with a Vestibulo-Cochlear Implant

    Directory of Open Access Journals (Sweden)

    T. A. K. Nguyen

    2017-11-01

    Full Text Available The peripheral vestibular system is critical for the execution of activities of daily life as it provides movement and orientation information to motor and sensory systems. Patients with bilateral vestibular hypofunction experience a significant decrease in quality of life and have currently no viable treatment option. Vestibular implants could eventually restore vestibular function. Most vestibular implant prototypes to date are modified cochlear implants to fast-track development. These use various objective measurements, such as the electrically evoked compound action potential (eCAP, to supplement behavioral information. We investigated whether eCAPs could be recorded in patients with a vestibulo-cochlear implant. Specifically, eCAPs were successfully recorded for cochlear and vestibular setups, as well as for mixed cochlear-vestibular setups. Similarities and slight differences were found for the recordings of the three setups. These findings demonstrated the feasibility of eCAP recording with a vestibulo-cochlear implant. They could be used in the short term to reduce current spread and avoid activation of non-targeted neurons. More research is warranted to better understand the neural origin of vestibular eCAPs and to utilize them for clinical applications.

  3. Recording and analysis of electrically evoked compound action potentials (ECAPs) with MED-EL cochlear implants and different artifact reduction strategies in Matlab.

    Science.gov (United States)

    Bahmer, Andreas; Peter, Otto; Baumann, Uwe

    2010-08-15

    Electrically evoked compound action potentials (ECAPs) are used in auditory research to evaluate the response of the auditory nerve to electrical stimulation. Animal preparations are typically used for the recording. With the introduction of a new generation of cochlear implants, however it is possible to record the response of the auditory nerve to electrical stimulation in humans as well, which is used in the clinic to test whether the implant works properly and whether the auditory nerve is responsive. Currently, ECAPs are used to estimate thresholds for speech processor programs. In addition, ECAPs recordings allow new research to be addressed, e.g., to evaluate enhanced electrical stimulation patterns. Research platforms are required to test user-defined stimuli and algorithms for the ECAPs analysis. Clinical fitting software that records ECAPs is not flexible enough for this purpose. To enable a larger group of scientists to pursue research in this field, we introduce a flexible setup that allows to change stimulation and recording parameters. ECAP recording and analysis software was developed in Matlab (The Mathworks, Inc.) for standard PC, using a National instruments (PCI-6533, National Instruments, Austin, TX) card and a Research Interface Box 2 (RIB2, Department of Ion Physics and Applied Physics at the University of Innsbruck, Innsbruck, Austria) for MED-EL cochlear implants. ECAP recordings of a human subject with three different artifact reduction methods (alternating, Miller modified masker-probe, triphasic pulses) are presented and compared. (c) 2010 Elsevier B.V. All rights reserved.

  4. Different action of a specific NR2B/NMDA antagonist Ro 25-6981 on cortical evoked potentials and epileptic afterdischarges in immature rats.

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    Szczurowska, Ewa; Mareš, Pavel

    2015-02-01

    Ro 25-6981 maleate is a highly selective and activity-dependent antagonist of NMDA ionotropic glutamate receptors containing NR2B subunit (NR2B/NMDARs). The aim of our study was to investigate the influence of Ro 25-6981 administration in developing rats on physiological (single and paired pulse cortical interhemispheric evoked potentials) and epileptic brain activity (cortical afterdischarges (ADs)). Electrophysiological experiments were performed in animals with epidurally implanted electrodes at postnatal days (P) P12, P18, and P25. The drug was injected intraperitoneally at a dose of 1 or 3mg/kg. Control animals were injected with saline (1ml/kg). Single interhemispheric responses were evoked with 0.5-ms biphasic pulses with intensities increasing from 0.4 to 5mA, paired-pulse responses were elicited by twofold threshold intensity. The ADs were elicited by series of 15-s of 1-ms pulses at 8-Hz frequency. Firstly, six stimulations with stable suprathreshold intensity repeated at 30-min intervals were used to determine the time course of Ro 25-6981 effects against ADs in P12 animals. Secondly, similar experiment was performed in all age groups of animals but with 20-min intervals as well as a further experiment using stimulations with stepwise intensities increasing at 10-min intervals from 0.2 to 15 mA. Pretreatment with the 3-mg/kg (but not the lower) dose of Ro 25-9681 decreased significantly the amplitude of single responses evoked with higher stimulation intensities in P12 and P18 animals. Both doses affected responses in P25 animals, only the 1-mg/kg dose was more efficacious than the 3-mg/kg one. Paired pulse responses were not affected by either dose of Ro 25-6981 in any age group. Ro 25-9681 clearly influenced the duration of ADs only in P12 animals. The 1-mg/kg dose did not change the duration of ADs whereas the 3-mg/kg dose suppressed progressive prolongation of ADs with repeated stimulations. This effect was seen even 110-min after the drug injection

  5. Across-site patterns of electrically evoked compound action potential amplitude-growth functions in multichannel cochlear implant recipients and the effects of the interphase gap.

    Science.gov (United States)

    Schvartz-Leyzac, Kara C; Pfingst, Bryan E

    2016-11-01

    Electrically evoked compound action potential (ECAP) measures of peak amplitude, and amplitude-growth function (AGF) slope have been shown to reflect characteristics of cochlear health (primarily spiral ganglion density) in anesthetized cochlear-implanted guinea pigs. Likewise, the effect of increasing the interphase gap (IPG) in each of these measures also reflects SGN density in the implanted guinea pig. Based on these findings, we hypothesize that suprathreshold ECAP measures, and also how they change as the IPG is increased, have the potential to be clinically applicable in human subjects. However, further work is first needed in order to determine the characteristics of these measures in humans who use cochlear implants. The current study examined across-site patterns of suprathreshold ECAP measures in 10 bilaterally-implanted, adult cochlear implant users. Results showed that both peak amplitude and slope of the AGF varied significantly from electrode to electrode in ear-specific patterns across the subjects' electrode arrays. As expected, increasing the IPG on average increased the peak amplitude and slope. Across ears, there was a significant, negative correlation between the slope of the ECAP AGF and the duration of hearing loss. Across-site patterns of ECAP peak amplitude and AGF slopes were also compared with common ground impedance values and significant correlations were observed in some cases, depending on the subject and condition. The results of this study, coupled with previous studies in animals, suggest that it is feasible to measure the change in suprathreshold ECAP measures as the IPG increases on most electrodes. Further work is needed to investigate the relationship between these measures and cochlear implant outcomes, and determine how these measures might be used when programming a cochlear-implant processor. Published by Elsevier B.V.

  6. Speech perception in nucleus CI24M cochlear implant users with processor settings based on electrically evoked compound action potential thresholds.

    Science.gov (United States)

    Smoorenburg, Guido F; Willeboer, Christina; van Dijk, Johannes E

    2002-01-01

    Adjusting the speech processor of a cochlear implant, per electrode, to the individual's response is a laborious task that may interfere with a user-friendly start of implant-mediated hearing, particularly in children. This research concerns the possibility of processor adjustment based on a profile derived from measurements of the electrically evoked compound action potential (ECAP) thresholds across the electrode array, followed by adjustment of the overall level of the profile to the hearing threshold and maximum comfortable loudness level using live voice. The results for CVC word lists show that speech perception is quite insensitive to the threshold setting of the speech processor. On average, the speech score does not decrease by more than 10% when, with the new method, the threshold setting comes out so much lower that the dynamic range has doubled. In contrast, the speech score appears to be sensitive to an increase of the maximum high-frequency stimulation settings for the basal electrodes, resulting in lower scores at these higher settings. The correlation between the overall ECAP thresholds and conventionally measured subjective thresholds is weak (r = 0.64). However, the correlation between the slopes of these threshold curves is satisfactory (r = 0.82). The correlation between the ECAP thresholds and the maximum stimulation levels is poor, both with respect to overall level and slope (r = 0.39 and 0.36, respectively). Applicability of the ECAP threshold in processor adjustment could not be demonstrated in this study. Prediction of the most critical factor in speech perception, the slope of the maximum stimulation curve, from the ECAP thresholds is poor. However, considering habituation to the initial processor setting of at least 6 months, the small decrease in the CVC scores with the new setting suggests that a more user-friendly adjustment procedure can be developed. Copyright 2002 S. Karger AG, Basel

  7. Deconvolution of the vestibular evoked myogenic potential.

    Science.gov (United States)

    Lütkenhöner, Bernd; Basel, Türker

    2012-02-07

    The vestibular evoked myogenic potential (VEMP) and the associated variance modulation can be understood by a convolution model. Two functions of time are incorporated into the model: the motor unit action potential (MUAP) of an average motor unit, and the temporal modulation of the MUAP rate of all contributing motor units, briefly called rate modulation. The latter is the function of interest, whereas the MUAP acts as a filter that distorts the information contained in the measured data. Here, it is shown how to recover the rate modulation by undoing the filtering using a deconvolution approach. The key aspects of our deconvolution algorithm are as follows: (1) the rate modulation is described in terms of just a few parameters; (2) the MUAP is calculated by Wiener deconvolution of the VEMP with the rate modulation; (3) the model parameters are optimized using a figure-of-merit function where the most important term quantifies the difference between measured and model-predicted variance modulation. The effectiveness of the algorithm is demonstrated with simulated data. An analysis of real data confirms the view that there are basically two components, which roughly correspond to the waves p13-n23 and n34-p44 of the VEMP. The rate modulation corresponding to the first, inhibitory component is much stronger than that corresponding to the second, excitatory component. But the latter is more extended so that the two modulations have almost the same equivalent rectangular duration. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Auditory and visual evoked potentials during hyperoxia

    Science.gov (United States)

    Smith, D. B. D.; Strawbridge, P. J.

    1974-01-01

    Experimental study of the auditory and visual averaged evoked potentials (AEPs) recorded during hyperoxia, and investigation of the effect of hyperoxia on the so-called contingent negative variation (CNV). No effect of hyperoxia was found on the auditory AEP, the visual AEP, or the CNV. Comparisons with previous studies are discussed.

  9. Comparison of electrically evoked compound action potential thresholds and loudness estimates for the stimuli used to program the Advanced Bionics cochlear implant.

    Science.gov (United States)

    Jeon, Eun Kyung; Brown, Carolyn J; Etler, Christine P; O'Brien, Sara; Chiou, Li-Kuei; Abbas, Paul J

    2010-01-01

    In the mid-1990s, Cochlear Corporation introduced a cochlear implant (CI) to the market that was equipped with hardware that made it possible to record electrically evoked compound action potentials (ECAPs) from CI users of all ages. Over the course of the next decade, many studies were published that compared ECAP thresholds with levels used to program the speech processor of the Nucleus CI. In 2001 Advanced Bionics Corporation introduced the Clarion CII cochlear implant (the Clarion CII internal device is also known as the CII Bionic Ear). This cochlear implant was also equipped with a system that allowed measurement of the ECAP. While a great deal is known about how ECAP thresholds compare with the levels used to program the speech processor of the Nucleus CI, relatively few studies have reported comparisons between ECAP thresholds and the levels used to program the speech processor of the Advanced Bionics CI. To explore the relationship between ECAP thresholds and behavioral measures of perceptual dynamic range for the range of stimuli commonly used to program the speech processor of the Advanced Bionics CI. This prospective and experimental study uses correlational and descriptive statistics to define the relationship between ECAP thresholds and perceptual dynamic range measures. Twelve postlingually deafened adults participated in this study. All were experienced users of the Advanced Bionics CI system. ECAP thresholds were recorded using the commercially available SoundWave software. Perceptual measures of threshold (T-level), most comfortable level (M-level), and maximum comfortable level (C-level) were obtained using both "tone bursts" and "speech bursts." The relationship between these perceptual and electrophysiological variables was defined using paired t-tests as well as correlation and linear regression. ECAP thresholds were significantly correlated with the perceptual dynamic range measures studied; however, correlations were not strong. Analysis of

  10. Mobile-phone pulse triggers evoked potentials.

    Science.gov (United States)

    Carrubba, Simona; Frilot, Clifton; Chesson, Andrew L; Marino, Andrew A

    2010-01-18

    If mobile-phone electromagnetic fields (EMFs) are hazardous, as suggested in the literature, processes or mechanisms must exist that allow the body to detect the fields. We hypothesized that the low-frequency pulses produced by mobile phones (217 Hz) were detected by sensory transduction, as evidenced by the ability of the pulses to trigger evoked potentials (EPs). Electroencephalograms (EEGs) were recorded from six standard locations in 20 volunteers and analyzed to detect brain potentials triggered by a pulse of the type produced by mobile phones. Evoked potentials having the expected latency were found in 90% of the volunteers, as assessed using a nonlinear method of EEG analysis. Evoked potentials were not detected when the EEG was analyzed using time averaging. The possibility of systematic error was excluded by sham-exposure analyses. The results implied that mobile-phones trigger EP at the rate of 217 Hz during ordinary phone use. Chronic production of the changes in brain activity might be pertinent to the reports of health hazards among mobile-phone users. (c) 2009 Elsevier Ireland Ltd. All rights reserved.

  11. Motor potentials evoked by paired cortical stimuli.

    Science.gov (United States)

    Inghilleri, M; Berardelli, A; Cruccu, G; Priori, A; Manfredi, M

    1990-01-01

    We recorded the motor evoked potentials (MEPs) from the abductor pollicis brevis muscle, after supramaximal electrical transcranial stimulation, and studied the effect of paired transcranial shocks with varying interstimulus time intervals, in 10 normal subjects, 4 patients with median nerve neuropathy and 2 patients with motoneurone disease. In relaxed muscles the amplitude of the MEP evoked by a single shock averaged 30% of the M wave. With intervals from 1 to 2.5 msec 2 shocks evoked one MEP far larger in size than the control MEP (70% of the M wave). With intervals of 10 msec and longer, the 2 shocks evoked 2 independent MEPs; the size of the MEP following the second shock (test) was inversely correlated with the size of the control MEP: the more the control MEP approached the size of the M wave, the smaller the test MEP. Single motor unit records showed that, in the normal subjects and patients with peripheral neuropathy, the same motor unit was activated either by the first or the second shock, whereas in the patients with motoneurone disease it fired twice. In active muscles, the control MEP averaged 70% of the M wave. With intervals of 10 msec and longer the test MEP was markedly suppressed; with 100 msec intervals it fully recovered. In relaxed muscles, by delivering a double shock at a 1.5 msec interval, thus evoking a large MEP, followed by a second double-shock, the test MEP was completely suppressed for a period of 20 msec; it began to recover at 50 msec intervals and fully recovered after 150 msec.(ABSTRACT TRUNCATED AT 250 WORDS)

  12. [Brainstem auditory evoked potentials and somatosensory evoked potentials in Chiari malformation].

    Science.gov (United States)

    Moncho, Dulce; Poca, María A; Minoves, Teresa; Ferré, Alejandro; Rahnama, Kimia; Sahuquillo, Juan

    2013-06-16

    Chiari malformations (CM) include a series of congenital anomalies involving the descent of the cerebellar tonsils below the foramen magnum, which may be associated with compression in the brainstem, upper spinal cord, and cranial nerves, consequently altering the responses of brainstem auditory evoked potentials (BAEP) and somatosensory evoked potentials (SSEP). However, only a small number of authors have described the indications of these tests in CM, and study groups to date have been small and heterogeneous. To review the results of BAEPs and SSEPs in published studies of patients with Chiari type 1 malformation (CM-1) or Chiari type 2 malformation (CM-2) as well as the indications of both tests in the diagnosis, treatment, and monitoring of both diseases, especially CM-1. We present a review article analyzing data from all published studies in Medline starting in 1966, located through PubMed, using combinations of the following keywords: 'Chiari malformation', 'Arnold-Chiari malformation', 'Chiari type 1 malformation', 'Arnold-Chiari type 1 malformation', 'evoked potentials', 'brainstem auditory evoked potentials' and 'somatosensory evoked potentials' as well as records of patients with CM-1 from the neurosurgery and neurophysiology departments at the Hospital Universitari Vall d'Hebron. Common findings of SSEP are a reduction in cortical amplitude from the posterior tibial nerve, a reduction or absence of cervical median nerve potential, and an increased N13-N20 interval. In BAEP, the most frequent findings are an increased I-V interval and a peripheral or cochlear auditory disturbance.

  13. Long Latency Auditory Evoked Potentials during Meditation.

    Science.gov (United States)

    Telles, Shirley; Deepeshwar, Singh; Naveen, Kalkuni Visweswaraiah; Pailoor, Subramanya

    2015-10-01

    The auditory sensory pathway has been studied in meditators, using midlatency and short latency auditory evoked potentials. The present study evaluated long latency auditory evoked potentials (LLAEPs) during meditation. Sixty male participants, aged between 18 and 31 years (group mean±SD, 20.5±3.8 years), were assessed in 4 mental states based on descriptions in the traditional texts. They were (a) random thinking, (b) nonmeditative focusing, (c) meditative focusing, and (d) meditation. The order of the sessions was randomly assigned. The LLAEP components studied were P1 (40-60 ms), N1 (75-115 ms), P2 (120-180 ms), and N2 (180-280 ms). For each component, the peak amplitude and peak latency were measured from the prestimulus baseline. There was significant decrease in the peak latency of the P2 component during and after meditation (Pmeditation facilitates the processing of information in the auditory association cortex, whereas the number of neurons recruited was smaller in random thinking and non-meditative focused thinking, at the level of the secondary auditory cortex, auditory association cortex and anterior cingulate cortex. © EEG and Clinical Neuroscience Society (ECNS) 2014.

  14. Pattern visual evoked potentials in malingering.

    Science.gov (United States)

    Nakamura, A; Akio, T; Matsuda, E; Wakami, Y

    2001-03-01

    We previously developed a new method for estimating objective visual acuity by means of pattern visual evoked potentials (PVEP). In this study, this method was applied to the diagnosis of malingering. Six patients ranging in age from 40 to 54 years (mean 47 years) with suspected malingering were evaluated by means of the visual evoked potential test, optokinetic nystagmus (OKN) inhibition test, and the visual field test. In the PVEP study, the stimulus consisted of black and white checkerboards (39', 26', 15', and 9') with a visual angle of 8 degrees, contrast level of 15%, and a frequency of 0.7 Hz. One hundred PVEP responses were averaged per session. Routine ophthalmic examinations were normal in all patients. Five patients had a tubularly constricted visual field, and the remaining patient had a normal visual field. The objective visual acuities of the six patients estimated from PVEP were better than their subjective visual acuities estimated with Landolt rings. Among a variety of psychophysical and electrophysiologic ancillary tests, we consider our PVEP method a useful method for objectively determining visual acuity in a patient with signs of ocular malingering.

  15. Different action of a specific NR2B/NMDA antagonist Ro 25-6981 on cortical evoked potentials and epileptic afterdischarges in immature rats

    Czech Academy of Sciences Publication Activity Database

    Szczurowska, Ewa; Mareš, Pavel

    2015-01-01

    Roč. 111, Jan 2015 (2015), s. 1-8 ISSN 0361-9230 R&D Projects: GA ČR(CZ) GBP304/12/G069 Institutional support: RVO:67985823 Keywords : cortical evoked responses * epileptic afterdischarges * subunits of NMDA receptors * ontogeny * rat Subject RIV: FH - Neurology Impact factor: 2.572, year: 2015

  16. Vestibular evoked myogenic potential in vestibular neuritis.

    Science.gov (United States)

    Nola, Giuseppe; Guastini, Luca; Crippa, Barbara; Deiana, Marco; Mora, Renzo; Ralli, Giovanni

    2011-11-01

    This study wants to show the diagnostic value of vestibular evoked myogenic potential (VEMP) in the diagnosis of vestibular neuritis (VN), independently of the caloric test results. Twenty patients were enrolled with acute vertigo caused by VN. VEMP was tested with the binaural simultaneous stimulation method. Surface electromyographic activity was recorded in the supine patients from symmetrical sites over the upper half of each sternocleidomastoid muscle, with a reference electrode on the lateral end of the upper sternum. During the acute attack, 8 days, 1 month and 3 months after the beginning of the acute attack, all the patients underwent the following examinations: Dix-Hallpike manoeuvre, Pagnini-McClure manoeuvre, head shaking test, pure-tone audiometry, tympanometry, caloric labyrinth stimulation according to the Fitzgerald-Hallpike method and VEMP. At the last visit, the 11 patients diagnosed with superior branch vestibular neuritis did not show any improvement at the caloric labyrinth stimulation and presented VEMP on both sides with normal amplitude and latency; in the 9 cases diagnosed with inferior branch vestibular neuritis, there was an improvement of the VEMP reflex and normal caloric test. Our experience highlights that VEMP recording is applicable for patients with VN as a screening test.

  17. Effects of aging on laser evoked potentials.

    Science.gov (United States)

    Creac'H, Christelle; Bertholon, Alexandre; Convers, Philippe; Garcia-Larrea, Luis; Peyron, Roland

    2015-05-01

    Aging has been reported to reduce the amplitude of laser evoked potentials. However, it is unknown whether this effect depends on the length of the sensory fibers. This is an important issue, because most painful neuropathies are length-dependent. We conducted a study of 40 healthy subjects, half of whom were older than age 50 years. Nociceptive stimuli were delivered to the feet and thighs using a CO2 laser stimulator. Detection and pain perception thresholds did not correlate with age. Latencies of N1, N2, and P2 correlated positively with age on the feet but not on the thighs, whereas the amplitude of N2-P2 decreased with age for both areas. The effects of aging on latencies may reflect a distal loss of peripheral inputs and a length-dependent de-synchronization of the ascending nociceptive volley. Additional changes in peripheral and central processes may explain the diffuse decrease of N2-P2 amplitudes observed with aging. © 2014 Wiley Periodicals, Inc.

  18. [Maturation of cerebral somatosensory evoked potentials].

    Science.gov (United States)

    Cadilhac, J; Zhu, Y; Georgesco, M; Echenne, B; Rodiere, M

    1985-07-01

    Cerebral somatosensory evoked potentials (SEPs) were elicited by stimulation of the median nerve and/or posterior tibial nerve in 117 children of 1 day to 16 years old. A major negative wave (N) was consistently recorded from the parietal region of the scalp when the arm was stimulated. The peak latency, the onset latency, the rising time and the duration of H wave are closely correlated with age and body length. The latencies are shortest in the subjects of 1-3 years old. SEPs to lower extremity stimulation were inconstant in the infants before the age of one. The major positive wave (P) has a variable topographic distribution along the middle line, over the scalp. The latencies are also very variable in the different subjects of the same age as well as in the same subject with different locations of active electrode. Among the parameters studied as for N wave, only the rising time of P wave is significantly correlated with age. The latencies of P wave have the shortest value in the subjects of 1-3 years old. The comparison of SEPs to upper and to lower limb stimulations shows that there is no relationship between them in respect to their morphology and amplitude. The minimum value of the latencies of N and P waves was observed at the same age but the difference between the peak latencies of P and N waves in the same subject increases considerably after 2 years of age and reaches the adult value after 5 years of age. These resultats indicate that the maturation of the peripheral somatosensory pathways proceeds at a higher rate than that of the central somatosensory pathways, that the maturation of the somatosensory pathways of the upper limb precedes that of the lower limb, and that the rising time of N or P waves is a good index of cortical maturation. The clinical utility of these SEPs in pediatrics is discussed.

  19. Pudendal somatosensory evoked potentials in normal women

    Directory of Open Access Journals (Sweden)

    Geraldo A. Cavalcanti

    2007-12-01

    Full Text Available OBJECTIVE: Somatosensory evoked potential (SSEP is an electrophysiological test used to evaluate sensory innervations in peripheral and central neuropathies. Pudendal SSEP has been studied in dysfunctions related to the lower urinary tract and pelvic floor. Although some authors have already described technical details pertaining to the method, the standardization and the influence of physiological variables in normative values have not yet been established, especially for women. The aim of the study was to describe normal values of the pudendal SSEP and to compare technical details with those described by other authors. MATERIALS AND METHODS: The clitoral sensory threshold and pudendal SSEP latency was accomplished in 38 normal volunteers. The results obtained from stimulation performed on each side of the clitoris were compared to ages, body mass index (BMI and number of pregnancies. RESULTS: The values of clitoral sensory threshold and P1 latency with clitoral left stimulation were respectively, 3.64 ± 1.01 mA and 37.68 ± 2.60 ms. Results obtained with clitoral right stimulation were 3.84 ± 1.53 mA and 37.42 ± 3.12 ms, respectively. There were no correlations between clitoral sensory threshold and P1 latency with age, BMI or height of the volunteers. A significant difference was found in P1 latency between nulliparous women and volunteers who had been previously submitted to cesarean section. CONCLUSIONS: The SSEP latency represents an accessible and reproducible method to investigate the afferent pathways from the genitourinary tract. These results could be used as normative values in studies involving genitourinary neuropathies in order to better clarify voiding and sexual dysfunctions in females.

  20. Somatosensory evoked potentials in children with autism

    OpenAIRE

    Hanan Galal Azouz; Mona Khalil; Hayam Moustafa Abd El Ghani; Hatim Mohamed Hamed

    2014-01-01

    Introduction: Autism is a neurodevelopmental disorder in the category of pervasive developmental disorders (PDD), which is characterized by widespread abnormalities of social interactions, communication, and severely restricted interests and highly repetitive behavior. Children with autism show sensory and perceptual abnormalities. They have either hyposensitivity or hypersensitivity to sensory, auditory, and visual stimuli. Objectives: The aim of this work was to study somatosensory evoke...

  1. Vibration and muscle contraction affect somatosensory evoked potentials

    OpenAIRE

    Cohen, LG; Starr, A

    1985-01-01

    We recorded potentials evoked by specific somatosensory stimuli over peripheral nerve, spinal cord, and cerebral cortex. Vibration attenuated spinal and cerebral potentials evoked by mixed nerve and muscle spindle stimulation; in one subject that was tested, there was no effect on cutaneous input. Presynaptic inhibition of Ia input in the spinal cord and muscle spindle receptor occupancy are probably the responsible mechanisms. In contrast, muscle contraction attenuated cerebral potentials to...

  2. Multichannel recording of median nerve somatosensory evoked potentials

    NARCIS (Netherlands)

    van de Wassenberg, W.; van der Hoeven, J.; Leenders, K.; Maurits, N.

    Objectives. -Clinical applications of multichannel (>= 64 electrodes) electroencephalography (EEG) have been limited so far. Amplitude variability of evoked potentials in healthy subjects is large, which limits their diagnostic applicability. This amplitude variability may be partially due to

  3. Can visual evoked potentials be used in biometric identification?

    Science.gov (United States)

    Power, Alan J; Lalor, Edmund C; Reilly, Richard B

    2006-01-01

    Due to known differences in the anatomical structure of the visual pathways and generators in different individuals, the use of visual evoked potentials offers the possibility of an alternative to existing biometrics methods. A study based on visual evoked potentials from 13 individuals was carried out to assess the best combination of temporal, spectral and AR modeling features to realize a robust biometric. From the results it can be concluded that visual evoked potentials show considerable biometric qualities, with classification accuracies reaching a high of 86.54% and that a specific temporal and spectral combination was found to be optimal. Based on these results the visual evoked potential may be a useful tool in biometric identification when used in conjunction with more established biometric methods.

  4. Analysis of Single Event Evoked Potentials.

    Science.gov (United States)

    1979-11-01

    stimuli is available in the literature, and since this study deals with single responses, an assumption had to be made before the information in the...Figue 4 Repon e mocekroadpten.trp atrsadt ln 0m10 4 4 22 A S10 2D 3 40 5 64 10 i 13 10 II0 Visul wo (miautes) of side of dck Figure 5. The effect of unit...differences in their average evoked responses. These responses will also lend themselves to detection based on information from multiple electrodes because

  5. Brainstem evoked potentials in infantile spasms; Comparison with MRI findings

    Energy Technology Data Exchange (ETDEWEB)

    Miyazaki, Masahito; Hashimoto, Toshiaki; Murakawa, Kazuyoshi; Tayama, Masanobu; Kuroda, Yasuhiro (Tokushima Univ. (Japan). School of Medicine)

    1992-08-01

    In ten patients with infantile spasms, brainstem evoked potentials and MRI examinations were performed to evaluate the brainstem involvement. The result of short latency somatosensory evoked potentials (SSEP) following the right median nerve stimulation revealed abnormal findings including the absence or low amplitudes of the waves below wave P3 and delayed central conduction time in 7 of the ten patients. The result of auditory brainstem responses (ABR) revealed abnormal findings including low amplitudes of wave V, prolonged interpeak latency of waves I-V and absence of the waves below wave IV in 5 of the ten patients. The result of the MRI examinations revealed various degrees of the brainstem atrophy in 6 of the ten patients, all of whom showed abnormal brainstem evoked potentials. The result of this study demonstrates that patients with infantile spasms are frequently associated with brainstem dysfunction and raises the possibility that brainstem atrophy might be a cause of infantile spasms. (author).

  6. Cortical evoked potentials to an auditory illusion: binaural beats.

    Science.gov (United States)

    Pratt, Hillel; Starr, Arnold; Michalewski, Henry J; Dimitrijevic, Andrew; Bleich, Naomi; Mittelman, Nomi

    2009-08-01

    To define brain activity corresponding to an auditory illusion of 3 and 6Hz binaural beats in 250Hz or 1000Hz base frequencies, and compare it to the sound onset response. Event-Related Potentials (ERPs) were recorded in response to unmodulated tones of 250 or 1000Hz to one ear and 3 or 6Hz higher to the other, creating an illusion of amplitude modulations (beats) of 3Hz and 6Hz, in base frequencies of 250Hz and 1000Hz. Tones were 2000ms in duration and presented with approximately 1s intervals. Latency, amplitude and source current density estimates of ERP components to tone onset and subsequent beats-evoked oscillations were determined and compared across beat frequencies with both base frequencies. All stimuli evoked tone-onset P(50), N(100) and P(200) components followed by oscillations corresponding to the beat frequency, and a subsequent tone-offset complex. Beats-evoked oscillations were higher in amplitude with the low base frequency and to the low beat frequency. Sources of the beats-evoked oscillations across all stimulus conditions located mostly to left lateral and inferior temporal lobe areas in all stimulus conditions. Onset-evoked components were not different across stimulus conditions; P(50) had significantly different sources than the beats-evoked oscillations; and N(100) and P(200) sources located to the same temporal lobe regions as beats-evoked oscillations, but were bilateral and also included frontal and parietal contributions. Neural activity with slightly different volley frequencies from left and right ear converges and interacts in the central auditory brainstem pathways to generate beats of neural activity to modulate activities in the left temporal lobe, giving rise to the illusion of binaural beats. Cortical potentials recorded to binaural beats are distinct from onset responses. Brain activity corresponding to an auditory illusion of low frequency beats can be recorded from the scalp.

  7. ROLE OF NMDA, NICOTINIC, AND GABA RECEPTORS IN THE STEADY STATE VISUAL EVOKED POTENTIAL IN RATS.

    Science.gov (United States)

    This manuscript characterizes the receptor pathways involved in pattern-evoked potential generation in rats" NMDA and nicotinic acetylcholine receptors appear to be involved in the generation of the steady-state pattern evoked response in vivo." The pattern evok...

  8. Single-sweep spectral analysis of contact heat evoked potentials

    DEFF Research Database (Denmark)

    Hansen, Tine M; Graversen, Carina; Frøkjaer, Jens B

    2015-01-01

    AIMS: The cortical response to nociceptive thermal stimuli recorded as contact heat evoked potentials (CHEPs) may be altered by morphine. However, previous studies have averaged CHEPs over multiple stimuli, which are confounded by jitter between sweeps. Thus, the aim was to assess single-sweep ch...

  9. Multichannel recording of tibial-nerve somatosensory evoked potentials

    NARCIS (Netherlands)

    de Wassenberg, W. J. G. van; Kruizinga, W. J.; van der Hoeven, J. H.; Leenders, K. L.; Maurits, N. M.

    2008-01-01

    Study aims. -The topography of the peaks of tibial.-nerve somatosensory evoked potential (SEP) varies among healthy subjects, most likely because of differences in position and orientation of their cortical generator(s). Therefore, amplitude estimation with a standard one- or two-channel derivation

  10. Cortical Auditory Evoked Potentials in Unsuccessful Cochlear Implant Users

    Science.gov (United States)

    Munivrana, Boska; Mildner, Vesna

    2013-01-01

    In some cochlear implant users, success is not achieved in spite of optimal clinical factors (including age at implantation, duration of rehabilitation and post-implant hearing level), which may be attributed to disorders at higher levels of the auditory pathway. We used cortical auditory evoked potentials to investigate the ability to perceive…

  11. Somatosensory evoked potentials in children with autism | Azouz ...

    African Journals Online (AJOL)

    They have either hyposensitivity or hypersensitivity to sensory, auditory, and visual stimuli. Objectives: The aimof thisworkwas to study somatosensory evoked potential (SSEPs) changesamong children with autism, and their relation to somatosensory manifestations and severity of autism. Subjects: Thirty children with ...

  12. Efeitos do potencial de ação neural sobre a percepção de fala em usuários de implante coclear Influence of evoked compound action potential on speech perception in cochlear implant users

    Directory of Open Access Journals (Sweden)

    Mariana Cardoso Guedes

    2007-08-01

    Full Text Available O Potencial de Ação Composto Evocado Eletricamente reflete a atividade do nervo auditivo, podendo ser registrado através dos eletrodos do implante coclear. A determinação dos elementos neurais estimuláveis pode contribuir para explicar a variabilidade de desempenho entre indivíduos implantados. OBJETIVO: Comparar o desempenho nos testes de percepção da fala entre pacientes que apresentaram e que não apresentaram potencial de ação composto evocado eletricamente no momento intra-operatório. MATERIAL E MÉTODO: Estudo prospectivo no qual 100 indivíduos usuários do implante coclear Nucleus 24 foram divididos em dois grupos de acordo com a presença ou ausência do potencial de ação intra-operatório. Após 6 meses de uso do dispositivo, os resultados dos testes de percepção de fala foram comparados entre os grupos. RESULTADOS: O potencial foi observado em 72% dos pacientes. A percepção no teste de frases em formato aberto foi melhor nos indivíduos com presença de potencial (média 82,8% contra 41,0%, p = 0,005. Houve associação entre ausência do potencial e etiologia da surdez por meningite. CONCLUSÃO: Ausência de potencial neural intraoperatório esteve associada ao pior desempenho na percepção da fala e à etiologia da surdez por meningite. Por outro lado, a presença do potencial de ação intraoperatório sugere ótimo prognóstico.Electrically Evoked Compound Action Potential is a measure of synchronous cochlear nerve fibers activity elicited by electrical stimulation of the cochlear implant. The electrophysiological nerve responses may contribute to explain the variability in individual performance of cochlear implant recipients. AIM: To compare speech perception tests’ performances of cochlear implant users according to the presence or absence of intraoperative neural telemetry responses. MATERIAL AND METHOD: Prospective study design with 100 "Nucleus 24" cochlear implant users divided in two groups according

  13. Visual evoked potentials in patients after methanol poisoning

    Directory of Open Access Journals (Sweden)

    Pavel Urban

    2016-06-01

    Full Text Available Objectives: We report the results of the visual evoked potentials (VEP examination in patients after severe poisoning by methanol. Material and Methods: The group of 47 patients (38 males and 9 females was assembled out of persons who survived an outbreak of poisoning by the methanol adulterated alcohol beverages, which happened in the Czech Republic in 2012–2013. The visual evoked potentials examination was performed using monocular checkerboard pattern-reversal stimulation. Two criteria of abnormality were chosen: missing evoked response, and wave P1 latency > 117 ms. Non-parametric statistical methods (median, range, and the median test were used to analyze factors influencing the VEP abnormality. Results: The visual evoked potential was abnormal in 20 patients (43%, 5 of them had normal visual acuity on the Snellen chart. The VEP abnormality did not correlate significantly with initial serum concentrations of methanol, formic acid or lactate; however, it showed statistically significant inverse relation to the initial serum pH: the subgroup with the abnormal VEP had significantly lower median pH in comparison with the subgroup with the normal VEP (7.16 vs. 7.34, p = 0.04. The abnormality was not related to chronic alcohol abuse. Conclusions: The visual evoked potentials examination appeared sensitive enough to detected even subclinical impairment of the optic system. Metabolic acidosis is likely to be the key factor related to the development of visual damage induced by methanol. The examination performed with a delay of 1–9 months after the poisoning documented the situation relatively early after the event. It is considered as a baseline for the planned long-term follow-up of the patients, which will make it possible to assess the dynamics of the observed changes, their reversibility, and the occurrence of potential late sequelae.

  14. Visual evoked potentials in patients after methanol poisoning.

    Science.gov (United States)

    Urban, Pavel; Zakharov, Sergey; Diblík, Pavel; Pelclová, Daniela; Ridzoň, Petr

    2016-01-01

    We report the results of the visual evoked potentials (VEP) examination in patients after severe poisoning by methanol. The group of 47 patients (38 males and 9 females) was assembled out of persons who survived an outbreak of poisoning by the methanol adulterated alcohol beverages, which happened in the Czech Republic in 2012-2013. The visual evoked potentials examination was performed using monocular checkerboard pattern-reversal stimulation. Two criteria of abnormality were chosen: missing evoked response, and wave P1 latency > 117 ms. Non-parametric statistical methods (median, range, and the median test) were used to analyze factors influencing the VEP abnormality. The visual evoked potential was abnormal in 20 patients (43%), 5 of them had normal visual acuity on the Snellen chart. The VEP abnormality did not correlate significantly with initial serum concentrations of methanol, formic acid or lactate; however, it showed statistically significant inverse relation to the initial serum pH: the subgroup with the abnormal VEP had significantly lower median pH in comparison with the subgroup with the normal VEP (7.16 vs. 7.34, p = 0.04). The abnormality was not related to chronic alcohol abuse. The visual evoked potentials examination appeared sensitive enough to detected even subclinical impairment of the optic system. Metabolic acidosis is likely to be the key factor related to the development of visual damage induced by methanol. The examination performed with a delay of 1-9 months after the poisoning documented the situation relatively early after the event. It is considered as a baseline for the planned long-term follow-up of the patients, which will make it possible to assess the dynamics of the observed changes, their reversibility, and the occurrence of potential late sequelae. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

  15. Multimodality evoked potentials in HTLV-I associated myelopathy.

    OpenAIRE

    Kakigi, R; Shibasaki, H; Kuroda, Y; Endo, C; Oda, K; Ikeda, A; Hashimoto, K

    1988-01-01

    Multimodality evoked potentials (EPs) consisting of somatosensory EPs (SEPs), visual EPs (VEPs) and brainstem auditory EPs (BAEPs) were studied in 16 cases with HTLV-I associated myelopathy (HAM). Median nerve SEPs were normal in all cases. In posterior tibial nerve SEPs, the potential recorded at the 12th thoracic spinal process was normal in every case but cortical components were significantly prolonged in 10 cases, although five of these showed no sensory impairment. BAEPs were normal in ...

  16. Auditory evoked potentials in children and adolescents with Down syndrome.

    Science.gov (United States)

    Gregory, Letícia; Rosa, Rafael F M; Zen, Paulo R G; Sleifer, Pricila

    2018-01-01

    Down syndrome, or trisomy 21, is the most common genetic alteration in humans. The syndrome presents with several features, including hearing loss and changes in the central nervous system, which may affect language development in children and lead to school difficulties. The present study aimed to investigate group differences in the central auditory system by long-latency auditory evoked potentials and cognitive potential. An assessment of 23 children and adolescents with Down syndrome was performed, and a control group composed of 43 children and adolescents without genetic and/or neurological changes was used for comparison. All children underwent evaluation with pure tone and vocal audiometry, acoustic immitance measures, long-latency auditory evoked potentials, and cognitive potential. Longer latencies of the waves were found in the Down syndrome group than the control group, without significant differences in amplitude, suggesting that individuals with Down syndrome have difficulty in discrimination and auditory memory. It is, therefore, important to stimulate and monitor these children in order to enable adequate development and improve their life quality. We also emphasize the importance of the application of auditory evoked potentials in clinical practice, in order to contribute to the early diagnosis of hearing alterations and the development of more research in this area. © 2017 Wiley Periodicals, Inc.

  17. Abdominal acupuncture reduces laser-evoked potentials in healthy subjects

    DEFF Research Database (Denmark)

    Pazzaglia, C.; Liguori, S.; Minciotti, I.

    2015-01-01

    Objective: Acupuncture is known to reduce clinical pain, although the exact mechanism is unknown. The aim of the current study was to investigate the effect of acupuncture on laser-evoked potential amplitudes and laser pain perception. Methods: In order to evaluate whether abdominal acupuncture...... is able to modify pain perception, 10 healthy subjects underwent a protocol in which laser-evoked potentials (LEPs) and laser pain perception were collected before the test (baseline), during abdominal acupuncture, and 15. min after needle removal. The same subjects also underwent a similar protocol...... in which, however, sham acupuncture without any needle penetration was used. Results: During real acupuncture, both N1 and N2/P2 amplitudes were reduced, as compared to baseline (p . < 0.01). The reduction lasted up to 15. min after needle removal. Furthermore, laser pain perception was reduced during...

  18. Vestibular evoked myogenic potentials (VEMPs) evoked by air- and bone-conducted stimuli in vestibular neuritis.

    Science.gov (United States)

    Govender, Sendhil; Dennis, Danielle L; Colebatch, James G

    2015-10-01

    To compare and characterise abnormalities for short latency vestibular evoked myogenic potentials (VEMPs) elicited by air- (AC) and two differing types of bone-conducted (BC) stimuli during vestibular neuritis (VN). AC (500Hz short tone bursts) and two BC stimuli (500Hz at the forehead and impulses at the mastoids) were used to evoke cervical and ocular potentials (cVEMPs and oVEMPs) in VN patients (n=22) and healthy subjects. More abnormalities were observed for the oVEMP than the cVEMP when using either AC 500Hz or BC 500Hz. The AC stimulus showed slightly more abnormalities than the BC 500Hz stimulus. In contrast, BC impulses produced frequent abnormalities for both oVEMPs and cVEMPs. The findings were modelled, based upon presumed selective lesions of the superior nerve. AC 500Hz stimulation was slightly better than BC 500Hz in demonstrating abnormalities in patients with VN. BC impulses behave as expected for a predominantly utricular stimulus. The relative contributions of saccular and utricular fibres differ for stimulus type and target reflex. AC 500Hz is as effective as BC 500Hz for investigating VN. BC impulses act most strongly on utricular afferents. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  19. Normalization reduces intersubject variability in cervical vestibular evoked myogenic potentials.

    Science.gov (United States)

    van Tilburg, Mark J; Herrmann, Barbara S; Guinan, John J; Rauch, Steven D

    2014-09-01

    Cervical vestibular evoked myogenic potentials are used to assess saccular and inferior vestibular nerve function. Normalization of the VEMP waveform has been proposed to reduce the variability in vestibular evoked myogenic potentials by correcting for muscle activation. In this study, we test the hypothesis that normalization of the raw cervical VEMP waveform causes a significant decrease in the intersubject variability. Prospective cohort study. Large specialty hospital, department of otolaryngology. Twenty healthy subjects were used in this study. All subjects underwent cervical vestibular evoked myogenic potential testing using short tone bursts at 250, 500, 750, and 1,000 Hz. Both intersubject and intrasubject variability was assessed. Variability between raw and normalized peak-to-peak amplitudes was compared using the coefficient of variation. Intrasubject variability was assessed using the intraclass correlation coefficient and interaural asymmetry ratio. cVEMPs were present in most ears. Highest peak-to-peak amplitudes were recorded at 750 Hz. Normalization did not alter cVEMP tuning characteristics. Normalization of the cVEMP response caused a significant reduction in intersubject variability of the peak-to-peak amplitude. No significant change was seen in the intrasubject variability. Normalization significantly reduces cVEMP intersubject variability in healthy subjects without altering cVEMP characteristics. By reducing cVEMP amplitude variation due to nonsaccular, muscle-related factors, cVEMP normalization is expected to improve the ability to distinguish between healthy and pathologic responses in the clinical application of cVEMP testing.

  20. Perceptual learning of acoustic noise generates memory-evoked potentials.

    Science.gov (United States)

    Andrillon, Thomas; Kouider, Sid; Agus, Trevor; Pressnitzer, Daniel

    2015-11-02

    Experience continuously imprints on the brain at all stages of life. The traces it leaves behind can produce perceptual learning [1], which drives adaptive behavior to previously encountered stimuli. Recently, it has been shown that even random noise, a type of sound devoid of acoustic structure, can trigger fast and robust perceptual learning after repeated exposure [2]. Here, by combining psychophysics, electroencephalography (EEG), and modeling, we show that the perceptual learning of noise is associated with evoked potentials, without any salient physical discontinuity or obvious acoustic landmark in the sound. Rather, the potentials appeared whenever a memory trace was observed behaviorally. Such memory-evoked potentials were characterized by early latencies and auditory topographies, consistent with a sensory origin. Furthermore, they were generated even on conditions of diverted attention. The EEG waveforms could be modeled as standard evoked responses to auditory events (N1-P2) [3], triggered by idiosyncratic perceptual features acquired through learning. Thus, we argue that the learning of noise is accompanied by the rapid formation of sharp neural selectivity to arbitrary and complex acoustic patterns, within sensory regions. Such a mechanism bridges the gap between the short-term and longer-term plasticity observed in the learning of noise [2, 4-6]. It could also be key to the processing of natural sounds within auditory cortices [7], suggesting that the neural code for sound source identification will be shaped by experience as well as by acoustics. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Brainstem auditory evoked potentials in children with lead exposure

    Directory of Open Access Journals (Sweden)

    Katia de Freitas Alvarenga

    2015-02-01

    Full Text Available Introduction: Earlier studies have demonstrated an auditory effect of lead exposure in children, but information on the effects of low chronic exposures needs to be further elucidated. Objective: To investigate the effect of low chronic exposures of the auditory system in children with a history of low blood lead levels, using an auditory electrophysiological test. Methods: Contemporary cross-sectional cohort. Study participants underwent tympanometry, pure tone and speech audiometry, transient evoked otoacoustic emissions, and brainstem auditory evoked potentials, with blood lead monitoring over a period of 35.5 months. The study included 130 children, with ages ranging from 18 months to 14 years, 5 months (mean age 6 years, 8 months ± 3 years, 2 months. Results: The mean time-integrated cumulative blood lead index was 12 µg/dL (SD ± 5.7, range:2.433. All participants had hearing thresholds equal to or below 20 dBHL and normal amplitudes of transient evoked otoacoustic emissions. No association was found between the absolute latencies of waves I, III, and V, the interpeak latencies I-III, III-V, and I-V, and the cumulative lead values. Conclusion: No evidence of toxic effects from chronic low lead exposures was observed on the auditory function of children living in a lead contaminated area.

  2. Cortical modulation of short-latency TMS-evoked potentials

    Directory of Open Access Journals (Sweden)

    Domenica eVeniero

    2013-01-01

    Full Text Available Transcranial magnetic stimulation - electroencephalogram (TMS-EEG co-registration offers the opportunity to test reactivity of brain areas across distinct conditions through TMS-evoked potentials (TEPs. Several TEPs have been described, their functional meaning being largely unknown. In particular, short-latency potentials peaking at 5 (P5 and 8 (N8 ms after the TMS pulse have been recently described, but because of their huge amplitude, the problem of whether their origin is cortical or not has been opened. To gain information about these components, we employed a protocol that modulates primary motor cortex excitability (MI through an exclusively cortical phenomena: low frequency stimulation of premotor area (PMC. TMS was applied simultaneously with EEG recording from 70 electrodes. Amplitude of TEPs evoked by 200 single-pulses TMS delivered over MI at 110% of resting motor threshold was measured before and after applying 900 TMS conditioning stimuli to left premotor cortex with 1 Hz repetition rate. Single subject analyses showed reduction in TEPs amplitude after PMC conditioning in a sample of participants and increase in TEPs amplitude in two subjects. No effects were found on corticospinal excitability as recorded by motor evoked potentials (MEPs. Furthermore, correlation analysis showed an inverse relation between the effects of the conditioning protocol on P5-N8 complex amplitude and MEPs amplitude. Because the effects of the used protocol have been ascribed to a cortical interaction between premotor area and MI, we suggest that despite the sign of P5-N8 amplitude modulation is not consistent across participant, this modulation could indicate, at least in part, their cortical origin. We conclude that with an accurate experimental procedure early-latency components can be used to evaluate the reactivity of the stimulated cortex.

  3. The division of attention and the human auditory evoked potential

    Science.gov (United States)

    Hink, R. F.; Van Voorhis, S. T.; Hillyard, S. A.; Smith, T. S.

    1977-01-01

    The sensitivity of the scalp-recorded, auditory evoked potential to selective attention was examined while subjects responded to stimuli presented to one ear (focused attention) and to both ears (divided attention). The amplitude of the N1 component was found to be largest to stimuli in the ear upon which attention was to be focused, smallest to stimuli in the ear to be ignored, and intermediate to stimuli in both ears when attention was divided. The results are interpreted as supporting a capacity model of attention.

  4. Multifocal visual evoked potentials in optic neuritis and multiple sclerosis

    DEFF Research Database (Denmark)

    Pihl-Jensen, Gorm; Schmidt, Mathias Falck; Frederiksen, Jette Lautrup

    2017-01-01

    Multifocal visual evoked potential (mf-VEP) represents a new approach to the classical full field (ff-)VEP with separate responses from up to 60 sectors of the visual field. A thorough literature survey of the use of mf-VEP in optic neuritis (ON) and multiple sclerosis (MS) is presented (38...... was shown between mf-VEP and OCT, ff-VEP, MRI (MTR, DTI), 30-2 standard automated perimetry and low-contrast-visual acuity. All but one study showed superior sensitivity and specificity compared to ff-VEP, especially with regards to small, peripheral lesions or lesions of the upper visual field. Mf-VEP has...

  5. Sensory and semantic activations evoked by action attributes of manipulable objects: Evidence from ERPs.

    Science.gov (United States)

    Lee, Chia-Lin; Huang, Hsu-Wen; Federmeier, Kara D; Buxbaum, Laurel J

    2018-02-15

    "Two route" theories of object-related action processing posit different temporal activation profiles of grasp-to-move actions (rapidly evoked based on object structure) versus skilled use actions (more slowly activated based on semantic knowledge). We capitalized on the exquisite temporal resolution and multidimensionality of Event-Related Potentials (ERPs) to directly test this hypothesis. Participants viewed manipulable objects (e.g., calculator) preceded by objects sharing either "grasp", "use", or no action attributes (e.g., bar of soap, keyboard, earring, respectively), as well as by action-unrelated but taxonomically-related objects (e.g., abacus); participants judged whether the two objects were related. The results showed more positive responses to "grasp-to-move" primed objects than "skilled use" primed objects or unprimed objects starting in the P1 (0-150 ms) time window and continuing onto the subsequent N1 and P2 components (150-300 ms), suggesting that only "grasp-to-move", but not "skilled use", actions may facilitate visual attention to object attributes. Furthermore, reliably reduced N400s (300-500 ms), an index of semantic processing, were observed to taxonomically primed and "skilled use" primed objects relative to unprimed objects, suggesting that "skilled use" action attributes are a component of distributed, multimodal semantic representations of objects. Together, our findings provide evidence supporting two-route theories by demonstrating that "grasp-to-move" and "skilled use" actions impact different aspects of object processing and highlight the relationship of "skilled use" information to other aspects of semantic memory. Copyright © 2017. Published by Elsevier Inc.

  6. Benchmark Dose Calculations for Methylmercury-Associated Delays on Evoked Potential Latencies in Two Cohorts of Children

    DEFF Research Database (Denmark)

    Murata, Katsuyuki; Budtz-Jørgensen, Esben; Grandjean, Philippe

    2002-01-01

    Methylmercury; benchmark dose; brainstem auditory evoked potentials; neurotoxicity; human health risk assessment......Methylmercury; benchmark dose; brainstem auditory evoked potentials; neurotoxicity; human health risk assessment...

  7. Are hormones psychoactive? Evoked potential investigations in man.

    Science.gov (United States)

    Saletu, B; Saletu, M; Herrmann, W M; Itil, T M

    1975-08-01

    The somatosensory evoked potential (SEP) of physically and mentally healthy male subjects was recorded before as well as 4 hours after administration of one single dose of placebo, cyproterone acetate (an antiandrogen), and mesterolone (an androgen). Quantitative evaluation of drug-induced changes in SEP latencies and amplitudes, which, when plotted in terms of t-values, result in the so-called "SEP profiles", did not demonstrate any significant alterations after placebo. Contrary to this, cyproterone acetate induced systematic and significant changes characterized by a latency increase in the early peaks and latency decrease in the late peaks of the SEP. Apart from the non-significant amplitude changes, such alterations were previously described by us as typical for drugs of the anxiolytic class. Mesterolone on the other hand, produced a significant latency decrease in the early part and a latency increase in the late part of the evoked response which was found to be typical for the SEP profiles of tricyclic antidepressants. The amplitude did not show any systematic changes. Based on step-wise discriminant analysis of these data we could significantly differentiate both hormones from placebo as well as from each other. A comparative analysis of low and high doses did not yield any significant differences between the two levels. It was concluded that both test substances have psychoactive properties; whereas cyproterone acetate reveals anxiolytic qualities, mesterolone exhibits antidepressant ones. These findings are discussed from the clinical as well as from the neurophysiological point of view.

  8. Somatosensory-evoked potentials as an add-on diagnostic ...

    African Journals Online (AJOL)

    Gihan A. Eltantawi

    2012-07-19

    Jul 19, 2012 ... a Department of Physical Medicine, Rheumatology and Rehabilitation, Faculty of Medicine, Alexandria University, Egypt ... Abbreviations: AP, anteroposterior; CMAP, compound muscle action potential; CT ... Conclusion: Dermatomal and mixed SEPs had added to the clinical and radiological assessment of.

  9. Assessment of visual disability using visual evoked potentials

    Directory of Open Access Journals (Sweden)

    Jeon Jihoon

    2012-08-01

    Full Text Available Abstract Background The purpose of this study is to validate the use of visual evoked potential (VEP to objectively quantify visual acuity in normal and amblyopic patients, and determine if it is possible to predict visual acuity in disability assessment to register visual pathway lesions. Methods A retrospective chart review was conducted of patients diagnosed with normal vision, unilateral amblyopia, optic neuritis, and visual disability who visited the university medical center for registration from March 2007 to October 2009. The study included 20 normal subjects (20 right eyes: 10 females, 10 males, ages 9–42 years, 18 unilateral amblyopic patients (18 amblyopic eyes, ages 19–36 years, 19 optic neuritis patients (19 eyes: ages 9–71 years, and 10 patients with visual disability having visual pathway lesions. Amplitude and latencies were analyzed and correlations with visual acuity (logMAR were derived from 20 normal and 18 amblyopic subjects. Correlation of VEP amplitude and visual acuity (logMAR of 19 optic neuritis patients confirmed relationships between visual acuity and amplitude. We calculated the objective visual acuity (logMAR of 16 eyes from 10 patients to diagnose the presence or absence of visual disability using relations derived from 20 normal and 18 amblyopic eyes. Results Linear regression analyses between amplitude of pattern visual evoked potentials and visual acuity (logMAR of 38 eyes from normal (right eyes and amblyopic (amblyopic eyes subjects were significant [y = −0.072x + 1.22, x: VEP amplitude, y: visual acuity (logMAR]. There were no significant differences between visual acuity prediction values, which substituted amplitude values of 19 eyes with optic neuritis into function. We calculated the objective visual acuity of 16 eyes of 10 patients to diagnose the presence or absence of visual disability using relations of y = −0.072x + 1.22 (−0.072. This resulted in a prediction

  10. SOMATOSENSORY EVOKED POTENTIALS IN DIABETES MELLITUS TYPE - 2

    Directory of Open Access Journals (Sweden)

    Rekha

    2015-10-01

    Full Text Available Diabetes mellitus is the most common metabolic disorder affecting majority of population. It is estimated that over 400 million people throughout the world have diabetes. It has progressed to be a pandemic from an epidemic causing morbidity and mortality in the population. Among the many complications of diabetes, diabetic neuropathies contribute majorly to the morbidity associated with the disease. Axonal conduction is affected by elevated levels of protein kinase c causing neuronal ischemia; decreased ce llular myoinositol affecting sodium potassium ATPase pump leads to decreased nerve conduction; Somatosensory E voked P otentials (SSEPs reflect the activity of somatosensory pathways mediated through the dorsal columns of the spinal cord and the specific so matosensory cortex. Recording of Somatosensory Evoked Potentials in diabetics is done to assess the sensory involvement of spinal cord. Presence of SEPs provides clear evidence for axonal continuity and by using different stimulation sites, the rate of reg eneration can be determined. Both onset and peak latencies of all SEP components are prolonged in patients with diabetes. Present study is done to compare somatosensory evoked potentials in diabetics and normal subjects. MATERIALS AND METHOD S: The present study was undertaken at the Upgraded Department of Physiology, Osmania Medical College, Koti, Hyderabad. The study was conducted on subjects, both male and female in the age group of 45 to 55 years, suffering from type II diabetes excluding other neurologi cal disorders. Non - invasive method of estimation of nerve conduction studies using SFEMG/EP — Electromyography or evoked potential system (Nicolet systems — USA using surface electrodes with automated computerized monitor attached with printer is used. RESUL TS : ANOVA showed statistically significant N9 latency (right & left sides. Latencies of all the components of SSEPs were more significant than amplitudes in Diabetic

  11. Assessment of visual disability using visual evoked potentials.

    Science.gov (United States)

    Jeon, Jihoon; Oh, Seiyul; Kyung, Sungeun

    2012-08-06

    The purpose of this study is to validate the use of visual evoked potential (VEP) to objectively quantify visual acuity in normal and amblyopic patients, and determine if it is possible to predict visual acuity in disability assessment to register visual pathway lesions. A retrospective chart review was conducted of patients diagnosed with normal vision, unilateral amblyopia, optic neuritis, and visual disability who visited the university medical center for registration from March 2007 to October 2009. The study included 20 normal subjects (20 right eyes: 10 females, 10 males, ages 9-42 years), 18 unilateral amblyopic patients (18 amblyopic eyes, ages 19-36 years), 19 optic neuritis patients (19 eyes: ages 9-71 years), and 10 patients with visual disability having visual pathway lesions. Amplitude and latencies were analyzed and correlations with visual acuity (logMAR) were derived from 20 normal and 18 amblyopic subjects. Correlation of VEP amplitude and visual acuity (logMAR) of 19 optic neuritis patients confirmed relationships between visual acuity and amplitude. We calculated the objective visual acuity (logMAR) of 16 eyes from 10 patients to diagnose the presence or absence of visual disability using relations derived from 20 normal and 18 amblyopic eyes. Linear regression analyses between amplitude of pattern visual evoked potentials and visual acuity (logMAR) of 38 eyes from normal (right eyes) and amblyopic (amblyopic eyes) subjects were significant [y = -0.072x + 1.22, x: VEP amplitude, y: visual acuity (logMAR)]. There were no significant differences between visual acuity prediction values, which substituted amplitude values of 19 eyes with optic neuritis into function. We calculated the objective visual acuity of 16 eyes of 10 patients to diagnose the presence or absence of visual disability using relations of y = -0.072x + 1.22 (-0.072). This resulted in a prediction reference of visual acuity associated with malingering vs. real

  12. Visual evoked potentials in children prenatally exposed to methylmercury

    DEFF Research Database (Denmark)

    Yorifuji, Takashi; Murata, Katsuyuki; Bjerve, Kristian S

    2013-01-01

    Prenatal exposure to methylmercury can cause both neurobehavioral deficits and neurophysiological changes. However, evidence of neurotoxic effects within the visual nervous system is inconsistent, possibly due to incomplete statistical adjustment for beneficial nutritional factors. We evaluated...... the effect of prenatal methylmercury exposure on visual evoked potential (VEP) latencies in Faroese children with elevated prenatal methylmercury exposure. A cohort of 182 singleton term births was assembled in the Faroe Islands during 1994-1995. At age 7 years, VEP tracings were obtained from 139 cohort...... with delayed latencies for VEP peak N145. After covariate adjustment, a delay of 2.22ms (p=0.02) was seen for each doubling of the mercury concentration in maternal hair. In agreement with neuropsychological findings, the present study suggests that prenatal methylmercury exposure may have an adverse effect...

  13. Visual evoked potentials and selective attention to points in space

    Science.gov (United States)

    Van Voorhis, S.; Hillyard, S. A.

    1977-01-01

    Visual evoked potentials (VEPs) were recorded to sequences of flashes delivered to the right and left visual fields while subjects responded promptly to designated stimuli in one field at a time (focused attention), in both fields at once (divided attention), or to neither field (passive). Three stimulus schedules were used: the first was a replication of a previous study (Eason, Harter, and White, 1969) where left- and right-field flashes were delivered quasi-independently, while in the other two the flashes were delivered to the two fields in random order (Bernoulli sequence). VEPs to attended-field stimuli were enhanced at both occipital (O2) and central (Cz) recording sites under all stimulus sequences, but different components were affected at the two scalp sites. It was suggested that the VEP at O2 may reflect modality-specific processing events, while the response at Cz, like its auditory homologue, may index more general aspects of selective attention.

  14. Conscious wireless electroretinogram and visual evoked potentials in rats.

    Directory of Open Access Journals (Sweden)

    Jason Charng

    Full Text Available The electroretinogram (ERG, retina and visual evoked potential (VEP, brain are widely used in vivo tools assaying the integrity of the visual pathway. Current recordings in preclinical models are conducted under anesthesia, which alters neural physiology and contaminates responses. We describe a conscious wireless ERG and VEP recording platform in rats. Using a novel surgical technique to chronically implant electrodes subconjunctivally on the eye and epidurally over the visual cortex, we are able to record stable and repeatable conscious ERG and VEP signals over at least 1 month. We show that the use of anaesthetics, necessary for conventional ERG and VEP measurements, alters electrophysiology recordings. Conscious visual electrophysiology improves the viability of longitudinal studies by eliminating complications associated with repeated anaesthesia. It will also enable uncontaminated assessment of drug effects, allowing the eye to be used as an effective biomarker of the central nervous system.

  15. Vestibular evoked myogenic potential responses in obstructive sleep apnea syndrome.

    Science.gov (United States)

    Mutlu, Murad; Bayır, Ömer; Yüceege, Melike B; Karagöz, Tuğba; Fırat, Hikmet; Özdek, Ali; Akın, İstemihan; Korkmaz, Hakan

    2015-11-01

    Obstructive sleep apnea syndrome (OSAS) provokes oxidative stress and ischemia, which affects the central nervous system. The degeneration of neurons in the brainstem due to periodic hypoxia can be evaluated by vestibular and audiologic tests. The objective of this study is to determine brainstem damage in severe OSAS patients with the help of vestibular evoked myogenic potential (VEMP) responses. Prospective, randomize, double-blind. Research-training hospital. We compared cervical vestibular evoked myogenic potential (cVEMP) responses between severe OSAS patients and a control group. 54 patients were included and divided into the OSAS group, with severe OSAS (apnea-hypopnea index, AHI >70), and a control group with snoring without OSAS (AHI <5). Both groups underwent cVEMP. Bilateral recordings with simultaneous binaural logon stimulations were used during VEMP recordings. The existing p1n1 and n2p2 responses, p1, n1, n2, and p2 latencies and amplitudes, and p1n1 and n2p2 intervals were measured. Statistically significant differences were revealed between patients and controls for the response rate of the p1n1, n2p2 and p1n1, n2p2 amplitudes. There were no significant differences between the two groups with respect to the latencies of p1, n1, n2 and p2, or the p1n1 and n2p2 intervals. The VEMP response rate was lower in severe OSAS patients, and all amplitudes were shorter than in healthy subjects. VEMP recordings in severe OSAS subjects demonstrates abnormalities in brainstem pathways. It appears that brainstem damage in severe OSAS can be detected by cVEMP recordings.

  16. Recording visual evoked potentials and auditory evoked P300 at 9.4T static magnetic field.

    Science.gov (United States)

    Arrubla, Jorge; Neuner, Irene; Hahn, David; Boers, Frank; Shah, N Jon

    2013-01-01

    Simultaneous recording of electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) has shown a number of advantages that make this multimodal technique superior to fMRI alone. The feasibility of recording EEG at ultra-high static magnetic field up to 9.4 T was recently demonstrated and promises to be implemented soon in fMRI studies at ultra high magnetic fields. Recording visual evoked potentials are expected to be amongst the most simple for simultaneous EEG/fMRI at ultra-high magnetic field due to the easy assessment of the visual cortex. Auditory evoked P300 measurements are of interest since it is believed that they represent the earliest stage of cognitive processing. In this study, we investigate the feasibility of recording visual evoked potentials and auditory evoked P300 in a 9.4 T static magnetic field. For this purpose, EEG data were recorded from 26 healthy volunteers inside a 9.4 T MR scanner using a 32-channel MR compatible EEG system. Visual stimulation and auditory oddball paradigm were presented in order to elicit evoked related potentials (ERP). Recordings made outside the scanner were performed using the same stimuli and EEG system for comparison purposes. We were able to retrieve visual P100 and auditory P300 evoked potentials at 9.4 T static magnetic field after correction of the ballistocardiogram artefact using independent component analysis. The latencies of the ERPs recorded at 9.4 T were not different from those recorded at 0 T. The amplitudes of ERPs were higher at 9.4 T when compared to recordings at 0 T. Nevertheless, it seems that the increased amplitudes of the ERPs are due to the effect of the ultra-high field on the EEG recording system rather than alteration in the intrinsic processes that generate the electrophysiological responses.

  17. Clinical application of visual evoked potential in orbital cellulitis of infants

    Directory of Open Access Journals (Sweden)

    Xiao-Juan Jing

    2014-07-01

    Full Text Available AIM: To explore the visual evoked potential in infantile orbital cellulitis' clinical applications by monitoring the visual evoked potential changes in infantile orbital cellulitis before, during and after treatment.METHODS: Twenty-three cases of CT diagnosed single orbital cellulitis were examined by the visual evoked potentials. The affected eyes as observation group, and healthy eyes as control group. Comparative observation of visual evoked potential changes in amplitude and incubation period before, during and after the treatment. RESULTS: Compared with the control group, the observation group's visual evoked potential changes included reduced amplitude, extended incubation period. With the treatment progress, the observation group had gradual increase in amplitude, gradual reduction in incubation period. CONCLUSION: In infantile orbital cellulitis, the use of visual evoked potentials is a simple, feasible and effective method to monitoring the visual function during the treatment.

  18. Classification of ADHD and BMD patients using visual evoked potential.

    Science.gov (United States)

    Nazhvani, Adeleh Dehghani; Boostani, Reza; Afrasiabi, Somayeh; Sadatnezhad, Khadijeh

    2013-11-01

    Children with Bipolar Mood Disorder (BMD) and those with Attention Deficit Hyperactivity Disorder (ADHD) share many clinical signs and symptoms; therefore, achieving an accurate diagnosis is still a challenge, especially in the first interview session. The main focus of this paper is to quantitatively classify the ADHD and BMD patients using their Visual Evoke Potential (VEP) features elicited from their Electroencephalogram (EEG) signals. In this study, 36 subjects were participated including 12 healthy ones, 12 patients with ADHD and 12 ones with BMD. The age of ADHD patients was 16.92±6.29 and for the BMD ones was 17.85±3.68. Their scalp EEG signals in the presence of visual stimulus were recorded using 22 silver electrodes located according to the 10-20 international recording protocol. To extract their VEP, first a preprocessing step was executed to remove the power line and movement artifacts. Afterward, the wavelet denoising and synchronous averaging were applied to the preprocessed trials in order to elicit the P100 component. To obtain interpretable features from the evoked patterns, amplitude and latency were extracted and applied to the 1-Nearest Neighbor (1NN) classifier due to the locally scattered distribution of the VEP features. The evaluation was performed according to leave-one(subject)-out method and the experimental results were led to 92.85% classification accuracy which is a fairly promising achievement to distinguish the BMD, ADHD, and healthy subjects from each other. From the physiological point of view, this result point out to the existence of significant difference in the neural activities of their visual system in the ADHD, BMD, and healthy subjects in response to a periodic optical stimulus. Copyright © 2013 Elsevier B.V. All rights reserved.

  19. [Intraoperative pain stimuli change somatosensory evoked potentials, but not auditory evoked potentials during isoflurane/nitrous oxide anesthesia].

    Science.gov (United States)

    Rundshagen, I; Kochs, E; Bischoff, P; Schulte am Esch, J

    1997-10-01

    Evoked potentials are used for intraoperative monitoring to assess changes of cerebral function. This prospective randomised study assesses the influence of surgical stimulation on midlatency components of somatosensory (SEPs) and auditory evoked potentials (AEPs) in anaesthetised patients. After approval of the Ethics Committee and written informed consent 36 orthopaedic patients (34 +/- 15 y, 73 +/- 14 kg. 1.71 +/- 0.07 m, ASA I-II) were randomly included in the study. Anaesthesia was induced with 1.5 micrograms/kg fentanyl, 0.3 mg/kg etomidate and 0.1 mg/kg vecuronium. The lungs were intubated and patients normoventilated in steady state anaesthesia with isoflurane (end-tidal 0.6%) and 66% nitrous oxide. 18 patients (group 1) were assigned to the SEP group: median nerve stimulation, recording at Erb, C 6 and the contralateral somatosensory cortex (N20, P25, N35) vs Fz. AEPs were recorded in group 2 (n = 18): binaural stimulation, recording at Cz versus linked mastoid (V, Na, Pa, Nb). Recordings were performed during 30 min before the start of surgery (baseline: BL), at skin incision (SURG1) and at the preparation of the periost (SURG2). Heart rate, mean arterial blood pressure, oxygen saturation, endtidal pCO2 and isoflurane (PetISO) concentrations were registered simultaneously. Data were analysed by one-way analysis of variance. Post hoc comparison were made by Mann-Whitney U-Wilcoxon Rank Sum Test with p beats/min) to SURG2 (76 +/- 12 beats/min). Increases of amplitudes of midlatency SEP amplitudes indicate increased nociceptive signal transmission which is not blunted by isoflurane-nitrous oxide anaesthesia. In contrast, unchanged AEPs indicate adequate levels of the hypnotic components of anaesthesia.

  20. Mapping human brain networks with cortico-cortical evoked potentials

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    Keller, Corey J.; Honey, Christopher J.; Mégevand, Pierre; Entz, Laszlo; Ulbert, Istvan; Mehta, Ashesh D.

    2014-01-01

    The cerebral cortex forms a sheet of neurons organized into a network of interconnected modules that is highly expanded in humans and presumably enables our most refined sensory and cognitive abilities. The links of this network form a fundamental aspect of its organization, and a great deal of research is focusing on understanding how information flows within and between different regions. However, an often-overlooked element of this connectivity regards a causal, hierarchical structure of regions, whereby certain nodes of the cortical network may exert greater influence over the others. While this is difficult to ascertain non-invasively, patients undergoing invasive electrode monitoring for epilepsy provide a unique window into this aspect of cortical organization. In this review, we highlight the potential for cortico-cortical evoked potential (CCEP) mapping to directly measure neuronal propagation across large-scale brain networks with spatio-temporal resolution that is superior to traditional neuroimaging methods. We first introduce effective connectivity and discuss the mechanisms underlying CCEP generation. Next, we highlight how CCEP mapping has begun to provide insight into the neural basis of non-invasive imaging signals. Finally, we present a novel approach to perturbing and measuring brain network function during cognitive processing. The direct measurement of CCEPs in response to electrical stimulation represents a potentially powerful clinical and basic science tool for probing the large-scale networks of the human cerebral cortex. PMID:25180306

  1. Usage of Multimodal Evoked Potentials in Diagnosis of Changes in Central Nervous System in Multiple Sclerosis

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    Bahar Özbek

    2011-03-01

    Full Text Available OBJECTIVE: Evoked potentials are used in the functional assessment of sensory and motor pathways. Conflicting results have been reported in different studies about the value of evoked potentials in demyelinating diseases. Over 80% of patients with multiple sclerosis present with a relapsing–remitting form of the disease. In this study we aimed to examine the value of each evoked potential to demonstrate the demyelinating lesions in a homogenous group of patients with relapsing remitting multiple sclerosis. We also aimed to examine the correlation between clinical status and evoked potential abnormalities. METHODS: Twenty patients with relapsing remitting multiple sclerosis and ten healthy volunteers were included in the study to evaluate the value of evoked potentials in a homogenous group. Visual, somatosensory and motor evoked potentials were measured and EDSS scores of the patients were calculated. RESULTS: Of 20 patients, 15 patients(75% had VEP abnormality, 14 patients (70% had MEP abnormality and 12 patients (60% had tibial SEP abnormality. All patients had at least one abnormal evoked potential measurement. The abnormality of evoked potentials also had a correlation with high EDSS scores. CONCLUSION: We concluded that evoked potentials, especially used in combination, are good markers to show the nervous damage in patients with multiple sclerosis

  2. Vestibular evoked myogenic potential findings in multiple sclerosis.

    Science.gov (United States)

    Escorihuela García, Vicente; Llópez Carratalá, Ignacio; Orts Alborch, Miguel; Marco Algarra, Jaime

    2013-01-01

    Multiple sclerosis is an inflammatory disease involving the occurrence of demyelinating, chronic neurodegenerative lesions in the central nervous system. We studied vestibular evoked myogenic potentials (VEMPs) in this pathology, to allow us to evaluate the saccule, inferior vestibular nerve and vestibular-spinal pathway non-invasively. There were 23 patients diagnosed with multiple sclerosis who underwent VEMP recordings, comparing our results with a control group consisting of 35 healthy subjects. We registered p13 and n23 wave latencies, interaural amplitude difference and asymmetry ratio between both ears. Subjects also underwent an otoscopy and audiometric examination. The prolongation of p13 and n23 wave latencies was the most notable characteristic, with a mean p13 wave latency of 19.53 milliseconds and a mean latency of 30.06 milliseconds for n23. In contrast, the asymmetry index showed no significant differences with our control group. In case of multiple sclerosis, the prolongation of the p13 and n23 VEMP wave latencies is a feature that has been attributed to slowing of conduction by demyelination of the vestibular-spinal pathway. In this regard, alteration of the response or lack thereof in these potentials has a locator value of injury to the lower brainstem. Copyright © 2013 Elsevier España, S.L. All rights reserved.

  3. Vestibular evoked myogenic potentials in patients with ankylosing spondylitis.

    Science.gov (United States)

    Özgür, Abdulkadir; Serdaroğlu Beyazal, Münevver; Terzi, Suat; Coşkun, Zerrin Özergin; Dursun, Engin

    2016-10-01

    Ankylosing spondylitis (AS) is a chronic systemic inflammatory disease with unknown etiology. Although sacroiliac joint involvement is the classic sign along with the formed immune mediators, it may result in immune-mediated inner ear disease and may cause damage to the audiovestibular system. Vestibular evoked myogenic potentials (VEMP) is a clinical reflex test used in the diagnosis of vestibular diseases and is performed by recording and evaluating the muscle potentials resulting from the stimulation of the vestibular system with different stimuli. The aim of this study is to evaluate the cervical VEMP test results in AS patients without vestibular symptoms. Thirty-three patients with AS and a control group of 30 healthy volunteers with similar demographic characteristics were evaluated in the study. VEMP wave latency, P13-N23 wave amplitude, and VEMP asymmetry ratio (VAR) values were compared between the groups. The relationship between clinical and laboratory findings of the AS patients and VEMP data were also investigated. Compared with healthy people, this study shows the response rate of patients with ankylosing spondylitis was reduced in the VEMP test, and P13-N23 wave amplitude showed a decrease in AS patients who had VEMP response (p ankylosing spondylitis. The data obtained from this study suggest that AS may lead to decreased sensitivity of the vestibular system.

  4. Laser Evoked Potentials in Early and Presymptomatic Huntington's Disease

    Science.gov (United States)

    de Tommaso, Marina; Franco, Giovanni; Ricci, Katia; Montemurno, Anna; Sciruicchio, Vittorio

    2016-01-01

    Pain was rarely studied in Huntington's disease (HD). We presently aimed to extend our previous study on pain pathways functions by laser evoked potentials (LEPs) to a larger cohort of early unmedicated HD patients and a small group of presymptomatic HD (PHD) subjects. Forty-two early HD patients, 10 PHD patients, and 64 controls were submitted to LEPs by right-hand stimulation. Two series of 30 laser stimuli were delivered, and artifact-free responses were averaged. The N1, N2, and P2 latencies were significantly increased and the N2P2 amplitude significantly reduced in HD patients compared to controls. In the HD group, the LEPs abnormalities correlated with functional decline. PHD subjects showed a slight and insignificant increase in LEPs latencies, which was inversely correlated with the possible age of HD clinical onset. Data of the present study seem to suggest that the functional state of nociceptive pathways as assessed by LEPs may be a potential biomarker of disease onset and progression. The assessment of pain symptoms in premanifest and manifest HD may also open a new scenario in terms of subtle disturbances of pain processing, which may have a role in the global burden of the disease. PMID:27087746

  5. Influence of visual angle on pattern reversal visual evoked potentials

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    Ruchi Kothari

    2014-01-01

    Full Text Available Purpose: The aim of this study was to find whether the visual evoked potential (VEP latencies and amplitude are altered with different visual angles in healthy adult volunteers or not and to determine the visual angle which is the optimum and most appropriate among a wide range of check sizes for the reliable interpretation of pattern reversal VEPs (PRVEPs. Materials and Methods: The present study was conducted on 40 healthy volunteers. The subjects were divided into two groups. One group consisted of 20 individuals (nine males and 11 females in the age range of 25-57 years and they were exposed to checks subtending a visual angle of 90, 120, and 180 minutes of arc. Another group comprised of 20 individuals (10 males and 10 females in the age range of 36-60 years and they were subjected to checks subtending a visual angle of 15, 30, and 120 minutes of arc. The stimulus configuration comprised of the transient pattern reversal method in which a black and white checker board is generated (full field on a VEP Monitor by an Evoked Potential Recorder (RMS EMG. EPMARK II. The statistical analysis was done by One Way Analysis of Variance (ANOVA using EPI INFO 6. Results: In Group I, the maximum (max. P100 latency of 98.8 ± 4.7 and the max. P100 amplitude of 10.05 ± 3.1 μV was obtained with checks of 90 minutes. In Group II, the max. P100 latency of 105.19 ± 4.75 msec as well as the max. P100 amplitude of 8.23 ± 3.30 μV was obtained with 15 minutes. The min. P100 latency in both the groups was obtained with checks of 120 minutes while the min. P100 amplitude was obtained with 180 minutes. A statistically significant difference was derived between means of P100 latency for 15 and 30 minutes with reference to its value for 120 minutes and between the mean value of P100 amplitude for 120 minutes and that of 90 and 180 minutes. Conclusion: Altering the size of stimulus (visual angle has an effect on the PRVEP parameters. Our study found that the 120

  6. Increased threshold of short-latency motor evoked potentials in transgenic mice expressing Channelrhodopsin-2.

    Science.gov (United States)

    Wu, Wei; Xiong, Wenhui; Zhang, Ping; Chen, Lifang; Fang, Jianqiao; Shields, Christopher; Xu, Xiao-Ming; Jin, Xiaoming

    2017-01-01

    Transgenic mice that express channelrhodopsin-2 or its variants provide a powerful tool for optogenetic study of the nervous system. Previous studies have established that introducing such exogenous genes usually does not alter anatomical, electrophysiological, and behavioral properties of neurons in these mice. However, in a line of Thy1-ChR2-YFP transgenic mice (line 9, Jackson lab), we found that short-latency motor evoked potentials (MEPs) induced by transcranial magnetic stimulation had a longer latency and much lower amplitude than that of wild type mice. MEPs evoked by transcranial electrical stimulation also had a much higher threshold in ChR2 mice, although similar amplitudes could be evoked in both wild and ChR2 mice at maximal stimulation. In contrast, long-latency MEPs evoked by electrically stimulating the motor cortex were similar in amplitude and latency between wild type and ChR2 mice. Whole-cell patch clamp recordings from layer V pyramidal neurons of the motor cortex in ChR2 mice revealed no significant differences in intrinsic membrane properties and action potential firing in response to current injection. These data suggest that corticospinal tract is not accountable for the observed abnormality. Motor behavioral assessments including BMS score, rotarod, and grid-walking test showed no significant differences between the two groups. Because short-latency MEPs are known to involve brainstem reticulospinal tract, while long-latency MEPs mainly involve primary motor cortex and dorsal corticospinal tract, we conclude that this line of ChR2 transgenic mice has normal function of motor cortex and dorsal corticospinal tract, but reduced excitability and responsiveness of reticulospinal tracts. This abnormality needs to be taken into account when using these mice for related optogenetic study.

  7. [Exploration of the optic and somatosensory pathways with cerebral evoked potentials].

    Science.gov (United States)

    Ghezzi, A; Zibetti, A

    1981-06-16

    Visual and somatosensorial evoked potentials are the electrical response, recorded on the scalp, that follows the presentation of visual and sensorial stimuli. After briefly mentioning the technical premises enabling evoked responses to be obtained from EEC activity, some cases are reported (demyelining, degenerative, compressive, ischaemic, anoxic pathology) where visual or sensory evoked potentials presented changes, proof of the usefulness of these techniques for the purposes of clinical documentation or for diagnosis in different fields of DNS pathology.

  8. Polar bear Ursus maritimus hearing measured with auditory evoked potentials.

    Science.gov (United States)

    Nachtigall, Paul E; Supin, Alexander Y; Amundin, Mats; Röken, Bengt; Møller, Thorsten; Mooney, T Aran; Taylor, Kristen A; Yuen, Michelle

    2007-04-01

    While there has been recent concern about the effects of sound on marine mammals, including polar bears, there are no data available measuring the hearing of any bear. The in-air hearing of three polar bears was measured using evoked auditory potentials obtained while tone pips were played to three individually anaesthetized bears at the Kolmården Djurpark. Hearing was tested in half-octave steps from 1 to 22.5 kHz. Measurements were not obtainable at 1 kHz and best sensitivity was found in the range from 11.2-22.5 kHz. Considering the tone pips were short and background noise measurements were available, absolute measurements were estimated based on an assumed mammalian integration time of 300 ms. These data show sensitive hearing in the polar bear over a wide frequency range and should cause those concerned with the introduction of anthropogenic noise into the polar bear's environment to operate with caution.

  9. Visual evoked potential and psychophysical contrast thresholds in glaucoma.

    Science.gov (United States)

    Abdullah, Siti Nurliyana; Sanderson, Gordon F; James, Andrew C; Vaegan; Maddess, Ted

    2014-04-01

    We compared the diagnostic power of electrophysiologically and psychophysically measured contrast thresholds for the diagnosis of glaucoma. Additionally, we investigated whether combining results from the two methods improved diagnostic power. Seven-eight subjects between 40 and 88 years formed the main study group: 21 normal controls (9 males) and 57 glaucoma patients (30 males) were tested. Twenty-two younger control subjects were also tested. Contrast thresholds were determined for a 1 cpd sinusoidal grating, subtending 41° × 52° modulated at 14.3 rps. The thresholds were based on the same staircase method applied to visual evoked potential (VEP) and psychophysical responses (Psyc). Diagnostic power was assessed by the percent area under the curve (%AUC) of receiver operating characteristic plots. Psyc showed significant age dependence, -0.10 ± 0.02 dB, while VEPs did not. Diagnostic performance for moderate and severe eyes combined was modest: Psyc 74 ± 9.0 % and VEP 72 ± 9.1 %, but improved significantly (p Psyc thresholds appeared to improve diagnostic power. Canonical correlation analysis indicated that they measured statistically independent aspects of glaucoma possibly related to disease severity. Adding the 20-s psychophysical test to a VEP test produced a significant benefit for a small time cost.

  10. Flash visual evoked potentials in diurnal birds of prey.

    Science.gov (United States)

    Dondi, Maurizio; Biaggi, Fabio; Di Ianni, Francesco; Dodi, Pier Luigi; Quintavalla, Fausto

    2016-01-01

    The objective of this pilot study was to evaluate the feasibility of Flash Visual Evoked Potentials (FVEPs) testing in birds of prey in a clinical setting and to describe the protocol and the baseline data for normal vision in this species. FVEP recordings were obtained from 6 normal adult birds of prey: n. 2 Harris's Hawks (Parabuteo unicinctus), n. 1 Lanner Falcon (Falco biarmicus), n. 2 Gyrfalcons (Falco rusticolus) and n. 1 Saker Falcon (Falco cherrug). Before carrying out VEP tests, all animals underwent neurologic and ophthalmic routine examination. Waveforms were analysed to identify reproducible peaks from random variation of baseline. At least three positive and negative peaks were highlighted in all tracks with elevated repeatability. Measurements consisted of the absolute and relative latencies of these peaks (P1, N1, P2, N2, P3, and N3) and their peak-to-peak amplitudes. Both the peak latency and wave morphology achieved from normal animals were similar to those obtained previously in other animal species. This test can be easily and safely performed in a clinical setting in birds of prey and could be useful for an objective assessment of visual function.

  11. Flash visual evoked potentials in diurnal birds of prey

    Directory of Open Access Journals (Sweden)

    Maurizio Dondi

    2016-07-01

    Full Text Available The objective of this pilot study was to evaluate the feasibility of Flash Visual Evoked Potentials (FVEPs testing in birds of prey in a clinical setting and to describe the protocol and the baseline data for normal vision in this species. FVEP recordings were obtained from 6 normal adult birds of prey: n. 2 Harris’s Hawks (Parabuteo unicinctus, n. 1 Lanner Falcon (Falco biarmicus, n. 2 Gyrfalcons (Falco rusticolus and n. 1 Saker Falcon (Falco cherrug. Before carrying out VEP tests, all animals underwent neurologic and ophthalmic routine examination. Waveforms were analysed to identify reproducible peaks from random variation of baseline. At least three positive and negative peaks were highlighted in all tracks with elevated repeatability. Measurements consisted of the absolute and relative latencies of these peaks (P1, N1, P2, N2, P3, and N3 and their peak-to-peak amplitudes. Both the peak latency and wave morphology achieved from normal animals were similar to those obtained previously in other animal species. This test can be easily and safely performed in a clinical setting in birds of prey and could be useful for an objective assessment of visual function.

  12. An Intelligent Decision System for Intraoperative Somatosensory Evoked Potential Monitoring.

    Science.gov (United States)

    Fan, Bi; Li, Han-Xiong; Hu, Yong

    2016-02-01

    Somatosensory evoked potential (SEP) is a useful, noninvasive technique widely used for spinal cord monitoring during surgery. One of the main indicators of a spinal cord injury is the drop in amplitude of the SEP signal in comparison to the nominal baseline that is assumed to be constant during the surgery. However, in practice, the real-time baseline is not constant and may vary during the operation due to nonsurgical factors, such as blood pressure, anaesthesia, etc. Thus, a false warning is often generated if the nominal baseline is used for SEP monitoring. In current practice, human experts must be used to prevent this false warning. However, these well-trained human experts are expensive and may not be reliable and consistent due to various reasons like fatigue and emotion. In this paper, an intelligent decision system is proposed to improve SEP monitoring. First, the least squares support vector regression and multi-support vector regression models are trained to construct the dynamic baseline from historical data. Then a control chart is applied to detect abnormalities during surgery. The effectiveness of the intelligent decision system is evaluated by comparing its performance against the nominal baseline model by using the real experimental datasets derived from clinical conditions.

  13. Pattern Visual Evoked Potentials Elicited by Organic Electroluminescence Screen

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    Celso Soiti Matsumoto

    2014-01-01

    Full Text Available Purpose. To determine whether organic electroluminescence (OLED screens can be used as visual stimulators to elicit pattern-reversal visual evoked potentials (p-VEPs. Method. Checkerboard patterns were generated on a conventional cathode-ray tube (S710, Compaq Computer Co., USA screen and on an OLED (17 inches, 320 × 230 mm, PVM-1741, Sony, Tokyo, Japan screen. The time course of the luminance changes of each monitor was measured with a photodiode. The p-VEPs elicited by these two screens were recorded from 15 eyes of 9 healthy volunteers (22.0 ± 0.8 years. Results. The OLED screen had a constant time delay from the onset of the trigger signal to the start of the luminescence change. The delay during the reversal phase from black to white for the pattern was 1.0 msec on the cathode-ray tube (CRT screen and 0.5 msec on the OLED screen. No significant differences in the amplitudes of P100 and the implicit times of N75 and P100 were observed in the p-VEPs elicited by the CRT and the OLED screens. Conclusion. The OLED screen can be used as a visual stimulator to elicit p-VEPs; however the time delay and the specific properties in the luminance change must be taken into account.

  14. Visual evoked potentials in rotogravure printers exposed to toluene.

    Science.gov (United States)

    Urban, P; Lukás, E

    1990-01-01

    Visual evoked potentials (VEPs) from stimulation by checkerboard pattern reversal were examined in 54 rotogravure printers exposed to toluene (all men, aged 22-64 years, duration of exposure 1-41 years). A control group consisted of 46 subjects (23 men and 23 women; aged 22-54 years). Compared with controls the exposed group showed more frequent responses with reduced reproducibility or absence of some waves, or both; the mean P1 wave latency was prolonged and mean amplitudes N1P1 and P1N2 were reduced. The VEPs were abnormal in 24% of workers. The frequency of abnormal VEPs correlated positively with the duration of exposure to toluene and also with the degree of alcohol drinking. No association was found between measurements of VEP and electroencephalogram (EEG) or electromyogram (EMG) examinations. A VEP measurement was made in 78% of the exposed workers two years after the first examination. No statistically significant difference between the two results was found. This suggests a marked stability of the observed VEP changes. These changes can be interpreted as a subclinical sign of dysfunction of the central nervous system (CNS) related to exposure to toluene and also to alcohol consumption. PMID:2271388

  15. Changes in vestibular evoked myogenic potentials after Meniere attacks.

    Science.gov (United States)

    Kuo, Shih-Wei; Yang, Ting-Hua; Young, Yi-Ho

    2005-09-01

    The aim of this study was to apply videonystagmography (VNG) and vestibular evoked myogenic potential (VEMP) tests to patients with Meniere attacks, to explore the mechanics of where saccular disorders may affect the semicircular canals. From January 2001 to December 2003, 12 consecutive patients with unilateral definite Meniere's disease with vertiginous attacks underwent VNG for recording spontaneous nystagmus, as well as VEMP tests. At the very beginning of the Meniere attack, the spontaneous nystagmus beat toward the lesion side in 5 patients (42%) and toward the healthy side in 7 patients (58%). Twenty-four hours later, only 6 patients (50%) showed spontaneous nystagmus beating toward the healthy side. Nevertheless, spontaneous nystagmus subsided in all patients within 48 hours. The VEMP test was performed within 24 hours of a Meniere attack; the VEMPs were normal in 4 patients and abnormal in 8 patients (67%). After 48 hours, 4 patients with initially abnormal VEMPs had resolution and return to normal VEMPs, and the other 4 patients still had absent VEMPs. Most patients (67%) with Meniere attacks revealed abnormal VEMPs, indicating that the saccule participates in a Meniere attack. This is an important idea that stimulates consideration of the mechanism of Meniere attacks.

  16. A Subspace Method for Dynamical Estimation of Evoked Potentials

    Directory of Open Access Journals (Sweden)

    Stefanos D. Georgiadis

    2007-01-01

    Full Text Available It is a challenge in evoked potential (EP analysis to incorporate prior physiological knowledge for estimation. In this paper, we address the problem of single-channel trial-to-trial EP characteristics estimation. Prior information about phase-locked properties of the EPs is assesed by means of estimated signal subspace and eigenvalue decomposition. Then for those situations that dynamic fluctuations from stimulus-to-stimulus could be expected, prior information can be exploited by means of state-space modeling and recursive Bayesian mean square estimation methods (Kalman filtering and smoothing. We demonstrate that a few dominant eigenvectors of the data correlation matrix are able to model trend-like changes of some component of the EPs, and that Kalman smoother algorithm is to be preferred in terms of better tracking capabilities and mean square error reduction. We also demonstrate the effect of strong artifacts, particularly eye blinks, on the quality of the signal subspace and EP estimates by means of independent component analysis applied as a prepossessing step on the multichannel measurements.

  17. Evaluation of visual evoked potentials in post-trauma eyes

    Directory of Open Access Journals (Sweden)

    Xin Zhou

    2013-10-01

    Full Text Available AIM: To analyze the visual evoked potentials(VEPof 189 eyes subjected to traumatic injury, and to explore the feasibility and method to applying VEP technology to the evaluation of visual acuity after eye trauma. METHODS: All the objects were volunteers who were grouped according to a random examination with the international standard visual acuity chart. The study determined spatial frequency in stimulation mode, P100 amplitude and latency. Then, the lowest spatial frequency(LSFwas analyzed and its relationship with visual acuity were studied. Finally this study discussed about the way to evaluate visual acuity with VEP and also compared the VEP evaluation results with the visual acuity chart. RESULTS: The LSF of 22', 11', 5', and 3' corresponded respectively to vision of 0.1-0.2, 0.3-0.5, 0.6-1.0, 1.2-1.5. There was a significant difference in P100 amplitude between eyes with different visual acuity, but there was no significant difference in P100 latency between these eyes. The random evaluation results of VEP combined with LSF and P100 amplitude were highly consistent with the results with international standard visual acuity chart. CONCLUSION: It is practicable to evaluate these volunteers' visual acuity with the VEP technology.

  18. [Auditory evoked potentials and acoustically-directed behavior of nestlings].

    Science.gov (United States)

    Khaiutin, S N; Dmitrieva, L P

    1982-01-01

    Characteristics of auditory evoked potentials (EP) were studied in 1.5 to 7.5 days old Pied Flycatchers nestlings (Ficedula hypoleuca) with chronically implanted electrodes in the field L (analogue of the mammal's auditory cortex). EPs simultaneously with behaviour were recorded in nestlings under conditions similar to natural, in response to "feeding" calls and pure tones of different frequency and intensity. It was found that EP generation thresholds do not depend on the sum total of factors which influence the organization of feeding behaviour. The EP generation threshold is by 13-36 dB (for different frequencies) below that of the appearance of feeding responses in nestling with a maximum high motivation. It is suggested that the realization of inborn behaviour with a signal basis needs not only an integration (formed in the process of embryogenesis) of a definite sensory input with a complex of structures of the "feeding centre", but also the presence of a massive modality-specific inflow.

  19. Test-retest reliability of visual-evoked potential habituation.

    Science.gov (United States)

    Rauschel, Veronika; Ruscheweyh, Ruth; Krafczyk, Siegbert; Straube, Andreas

    2016-08-01

    Habituation of visual-evoked potentials (VEPs) is typically described as deficient interictally in migraine patients, supposedly indicating altered cortical excitability. Use of this parameter for monitoring changes over time, e.g. under treatment, requires demonstration of test-retest reliability. VEPs were recorded interictally in 41 episodic migraine patients and 40 controls. N75-P100 amplitudes were measured over six consecutive blocks of 75 VEPs each. Amplitude regression slopes and block ratios were used to quantify VEP habituation. Test-retest reliability was assessed over 15 minutes and two to three weeks. Controls showed significantly more negative VEP habituation slopes than migraine patients (-0.21 ± 0.40 vs. 0.04 ± 0.46 µV/block, p test to two- to three-week retest (p test-retest correlations were mostly poor both in migraine patients and controls (intraclass correlation coefficients, 15 minutes: -0.13 to 0.30, two to three weeks: 0.07 to 0.59). Deficient VEP habituation in migraine was confirmed. However, the test-retest reliability of VEP habituation was rather weak. Therefore, we suggest that VEP habituation should be used for evaluation of cortical excitability under treatment only at the group level and only when a control group with sham treatment is included. © International Headache Society 2015.

  20. Single-trial detection for intraoperative somatosensory evoked potentials monitoring.

    Science.gov (United States)

    Hu, L; Zhang, Z G; Liu, H T; Luk, K D K; Hu, Y

    2015-12-01

    Abnormalities of somatosensory evoked potentials (SEPs) provide effective evidence for impairment of the somatosensory system, so that SEPs have been widely used in both clinical diagnosis and intraoperative neurophysiological monitoring. However, due to their low signal-to-noise ratio (SNR), SEPs are generally measured using ensemble averaging across hundreds of trials, thus unavoidably producing a tardiness of SEPs to the potential damages caused by surgical maneuvers and a loss of dynamical information of cortical processing related to somatosensory inputs. Here, we aimed to enhance the SNR of single-trial SEPs using Kalman filtering and time-frequency multiple linear regression (TF-MLR) and measure their single-trial parameters, both in the time domain and in the time-frequency domain. We first showed that, Kalman filtering and TF-MLR can effectively capture the single-trial SEP responses and provide accurate estimates of single-trial SEP parameters in the time domain and time-frequency domain, respectively. Furthermore, we identified significant correlations between the stimulus intensity and a set of indicative single-trial SEP parameters, including the correlation coefficient (between each single-trial SEPs and their average), P37 amplitude, N45 amplitude, P37-N45 amplitude, and phase value (at the zero-crossing points between P37 and N45). Finally, based on each indicative single-trial SEP parameter, we investigated the minimum number of trials required on a single-trial basis to suggest the existence of SEP responses, thus providing important information for fast SEP extraction in intraoperative monitoring.

  1. Study on change of multi-modally evoked potentials in nasopharyngeal carcinoma patients after radiotherapy

    International Nuclear Information System (INIS)

    Qin Ling; Chen Jiaxin; Zhang Lixiang; Wang Tiejian; Han Min; Lu Xiaoling

    2001-01-01

    Objective: To investigate possible changes of multi-modally evoked potentials in nasopharyngeal carcinoma patients after radiotherapy. Methods: Altogether 48 nasopharyngeal carcinoma patients receiving primary conventional external beam irradiation were examined before and after radiotherapy to determine their brainstem auditory-evoked potential (BAEP), short-latency somatosensory-evoked potential (SLSEP) and pattern reversal visual-evoked potential (PRVEP). Results: In comparison with the conditions before radiotherapy, in different periods after radiotherapy abnormal peak latency and interval latency difference were found in BAEP, SLSEP and PRVEP. Conclusion: Nasopharyngeal carcinoma after radiotherapy may cause abnormal function of nerve conduction in early periods, which can be showed by BAEP, SLSEP, PRVEP, and injury can be timely detected if the three evoked potentials are used together. Thus authors suggest BAEP, SLSEP, PRVEP should be examined in nasopharyngeal carcinoma patients during and after the radiotherapy so as to find early damage in auditory somatosensory and visual conduction pathways

  2. Visual Evoked Potential to Assess Retinopathy in Gestational Diabetes Mellitus.

    Science.gov (United States)

    Hari Kumar, K V S; Ahmad, F M H; Sood, Sandeep; Mansingh, Sudhir

    2016-04-01

    We evaluated for early retinopathy using the visual evoked potential (VEP) in patients with gestational diabetes mellitus (GDM) and type 2 diabetes mellitus during pregnancy. All patients with GDM and type 2 diabetes seen between June and October of 2014 were included in this cross-sectional, observational study. Patients with secondary diabetes, ocular or major illness were excluded from the study. VEP was recorded in both eyes to derive prominent positive peak latency (P100), amplitude and initial negative deflection (N75) latency. The data were compared with 10 gestational age-matched controls with normal glucose tolerance. Appropriate statistical methods were used for comparison among the 3 groups. The study participants (40 with GDM, 10 with type 2 diabetes, 10 with normal glucose tolerance) had a median (25th to 75th interquartile range) age of 26 (24.3, 30) years, a gestational age of 24.5 (21, 27) weeks and weights of 66.8 (63.4, 71.5) kg. The P100 latencies were comparable among the 3 groups (p=0.0577). However, patients with any diabetes (GDM and type 2 diabetes) had prolonged P100 latencies (p=0.0139) and low P100 amplitudes (p=0.0391) in comparison to controls. P100 latency showed a direct correlation with hyperglycemia (p=0.0118). Our data showed that VEP abnormalities are detectable even in the short-term hyperglycemia of GDM and type 2 diabetes. Copyright © 2016 Canadian Diabetes Association. Published by Elsevier Inc. All rights reserved.

  3. Alterations in oropharyngeal sensory evoked potentials (PSEP) with Parkinson's disease.

    Science.gov (United States)

    Pitts, Teresa; Hegland, Karen Wheeler; Sapienza, Christine M; Bolser, Donald C; Davenport, Paul W

    2016-07-15

    Movement of a food bolus from the oral cavity into the oropharynx activates pharyngeal sensory mechanoreceptors. Using electroencephalography, somatosensory cortical-evoked potentials resulting from oropharyngeal mechanical stimulation (PSEP) have been studied in young healthy individuals. However, limited information is known about changes in processing of oropharyngeal afferent signals with Parkinson's disease (PD). To determine if sensory changes occurred with a mechanical stimulus (air-puff) to the oropharynx, two stimuli (S1-first; S2-s) were delivered 500ms apart. Seven healthy older adults (HOA; 3 male and 4 female; 72.2±6.9 years of age), and thirteen persons diagnosed with idiopathic Parkinson's disease (PD; 11 male and 2 female; 67.2±8.9 years of age) participated. Results demonstrated PSEP P1, N1, and P2 component peaks were identified in all participants, and the N2 peak was present in 17/20 participants. Additionally, the PD participants had a decreased N2 latency and gated the P1, P2, and N2 responses (S2/S1 under 0.6). Compared to the HOAs, the PD participants had greater evidence of gating the P1 and N2 component peaks. These results suggest that persons with PD experience changes in sensory processing of mechanical stimulation of the pharynx to a greater degree than age-matched controls. In conclusion, the altered processing of sensory feedback from the pharynx may contribute to disordered swallow in patients with PD. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Brainstem auditory-evoked potential in Boxer dogs

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    Mariana Isa Poci Palumbo

    2014-10-01

    Full Text Available Brainstem auditory-evoked potential (BAEP has been widely used for different purposes in veterinary practice and is commonly used to identify inherited deafness and presbycusis. In this study, 43 Boxer dogs were evaluated using the BAEP. Deafness was diagnosed in 3 dogs (2 bilateral and 1 unilateral allowing the remaining 40 Boxers to be included for normative data analysis including an evaluation on the influence of age on the BAEP. The animals were divided into 2 groups of 20 Boxers each based on age. The mean age was 4.54 years (range, 1-8 in group I, and 9.83 years (range, 8.5-12 in group II. The mean latency for I, III, and V waves were 1.14 (±0.07, 2.64 (±0.11, and 3.48 (±0.10 ms in group I, and 1.20 (±0.12, 2.73 (±0.15, and 3.58 (±0.22 ms in group II, respectively. The mean inter-peak latencies for the I-III, III-V and I-V intervals were 1.50 (±0.15, 0.84 (±0.15, and 2.34 (±0.11 ms in group I, and 1.53 (±0.16, 0.85 (±0.15, and 2.38 (±0.19 ms in group II, respectively. Latencies of waves I and III were significant different between group I and II. For the I-III, III-V and I-V intervals, no significant differences were observed between the 2 groups. As far as we know, this is the first normative study of BAEP obtained from Boxer dogs.

  5. The effect of changes in perilymphatic K+ on the vestibular evoked potential in the guinea pig

    NARCIS (Netherlands)

    Kingma, C. M.; Wit, H. P.

    2010-01-01

    To investigate the effect on the functioning of the vestibular system of a rupture of Reissner's membrane, artificial endolymph was injected in scala media of ten guinea pigs and vestibular evoked potentials (VsEPs), evoked by vertical acceleration pulses, were measured. Directly after injection of

  6. Visual cortical somatosensory and brainstem auditory evoked potentials following incidental irradiation of the rhombencephalon

    Energy Technology Data Exchange (ETDEWEB)

    Nightingale, S. (Royal Victoria Infirmary, Newcastle upon Tyne (UK)); Schofield, I.S.; Dawes, P.J.D.K. (Newcastle upon Tyne Univ. (UK). Newcastle General Hospital)

    1984-01-01

    Visual, cortical somatosensory and brainstem auditory evoked potentials were recorded before incidental irradiation of the rhombencephalon during radiotherapy in and around the middle ear, and at 11 weeks and eight months after completion of treatment. No patient experienced neurological symptoms during this period. No consistent changes in evoked potentials were found. The failure to demonstrate subclinical radiation-induced demyelination suggests either that the syndrome of early-delayed radiation rhombencephalopathy occurs in an idiosyncratic manner, or that any subclinical lesions are not detectable by serial evoked potential recordings.

  7. Visual cortical somatosensory and brainstem auditory evoked potentials following incidental irradiation of the rhombencephalon

    International Nuclear Information System (INIS)

    Nightingale, S.; Schofield, I.S.; Dawes, P.J.D.K.

    1984-01-01

    Visual, cortical somatosensory and brainstem auditory evoked potentials were recorded before incidental irradiation of the rhombencephalon during radiotherapy in and around the middle ear, and at 11 weeks and eight months after completion of treatment. No patient experienced neurological symptoms during this period. No consistent changes in evoked potentials were found. The failure to demonstrate subclinical radiation-induced demyelination suggests either that the syndrome of early-delayed radiation rhombencephalopathy occurs in an idiosyncratic manner, or that any subclinical lesions are not detectable by serial evoked potential recordings. (author)

  8. NLP-12 engages different UNC-13 proteins to potentiate tonic and evoked release.

    Science.gov (United States)

    Hu, Zhitao; Vashlishan-Murray, Amy B; Kaplan, Joshua M

    2015-01-21

    A neuropeptide (NLP-12) and its receptor (CKR-2) potentiate tonic and evoked ACh release at Caenorhabditis elegans neuromuscular junctions. Increased evoked release is mediated by a presynaptic pathway (egl-30 Gαq and egl-8 PLCβ) that produces DAG, and by DAG binding to short and long UNC-13 proteins. Potentiation of tonic ACh release persists in mutants deficient for egl-30 Gαq and egl-8 PLCβ and requires DAG binding to UNC-13L (but not UNC-13S). Thus, NLP-12 adjusts tonic and evoked release by distinct mechanisms. Copyright © 2015 the authors 0270-6474/15/351038-05$15.00/0.

  9. Enhanced auditory evoked potentials in musicians: A review of recent findings

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    Himanshu Kumar Sanju

    2016-06-01

    Full Text Available Auditory evoked potentials serve as an objective mode for assessment to check the functioning of the auditory system and neuroplasticity. Literature has reported enhanced electrophysiological responses in musicians, which shows neuroplasticity in musicians. Various databases including PubMed, Google, Google Scholar and Medline were searched for references related to auditory evoked potentials in musicians from 1994 till date. Different auditory evoked potentials in musicians have been summarized in the present article. The findings of various studies may support as evidences for music-induced neuroplasticity which can be used for the treatment of various clinical disorders. The search results showed enhanced auditory evoked potentials in musicians compared to non-musicians from brainstem to cortical levels. Also, the present review showed enhanced attentive and pre-attentive skills in musicians compared to non-musicians.

  10. Combined evoked potentials in co-occuring attention deficit hyperactivity disorder and epilepsy.

    Science.gov (United States)

    Major, Zoltán Zsigmond

    2011-07-30

    Evoked potentials, both stimulus related and event related, show disturbances in attention deficit-hyperactivity disorder and epilepsies, too. This study was designed to evaluate if these potentials are characteristically influenced by the presence of the two diseases, individually, and in the case of co-occurrence. Forty children were included, and four groups were formed, control group, ADHD group, epilepsy group and a group with the comorbidity of epilepsy and ADHD. Epilepsy patients were under proper antiepileptic treatment; ADHD patients were free of specific therapy. Brainstem auditory evoked potentials, visual evoked potentials and auditory P300 evaluation were performed. The latency of the P100 and N135 visual evoked potential components was significantly extended by the presence of epilepsy. If ADHD was concomitantly present, this effect was attenuated. Brainstem auditory evoked potential components were prolonged in the presence of the comorbidity, considering the waves elicited in the brainstem. P300 latencies were prolonged by the presence of co-occurring ADHD and epilepsy. Feedback parameters showed overall reduction of the tested cognitive performances in the ADHD group. Disturbances produced by the presence of ADHD-epilepsy comorbidity reveal hypothetically a linked physiopathological path for both diseases, and offers an approach with possible diagnostic importance, combined evoked potential recordings.

  11. Visual evoked potentials in Negro carriers of the gene for tyrosinase positive oculocutaneous albinism.

    Science.gov (United States)

    Castle, D; Kromberg, J; Kowalsky, R; Moosa, R; Gillman, N; Zwane, E; Fritz, V

    1988-01-01

    Visual evoked potential testing was performed on 15 Negro carriers of the gene for tyrosinase positive oculocutaneous albinism in order to detect whether they have the same visual pathway decussation anomalies as do homozygotes. No subject showed 01-02 asymmetry on monocular testing, indicating that decussation follows the normal pattern. It is concluded that visual evoked potential testing is probably not useful in the detection of Negroes heterozygous for the gene for tyrosinase positive oculocutaneous albinism. PMID:3148727

  12. Awareness during anaesthesia for surgery requiring evoked potential monitoring: A pilot study

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    Pritish J Korula

    2017-01-01

    Full Text Available Background: Evoked potential monitoring such as somatosensory-evoked potential (SSEP or motor-evoked potential (MEP monitoring during surgical procedures in proximity to the spinal cord requires minimising the minimum alveolar concentrations (MACs below the anaesthetic concentrations normally required (1 MAC to prevent interference in amplitude and latency of evoked potentials. This could result in awareness. Our primary objective was to determine the incidence of awareness while administering low MAC inhalational anaesthetics for these unique procedures. The secondary objective was to assess the adequacy of our anaesthetic technique from neurophysiologist′s perspective. Methods: In this prospective observational pilot study, 61 American Society of Anesthesiologists 1 and 2 patients undergoing spinal surgery for whom intraoperative evoked potential monitoring was performed were included; during the maintenance phase, 0.7-0.8 MAC of isoflurane was targeted. We evaluated the intraoperative depth of anaesthesia using a bispectral (BIS index monitor as well as the patients response to surgical stimulus (PRST scoring system. Post-operatively, a modified Bruce questionnaire was used to verify awareness. The adequacy of evoked potential readings was also assessed. Results: Of the 61 patients, no patient had explicit awareness. Intraoperatively, 19 of 61 patients had a BIS value of above sixty at least once, during surgery. There was no correlation with PRST scoring and BIS during surgery. Fifty-four out of 61 patient′s evoked potential readings were deemed ′good′ or ′fair′ for the conduct of electrophysiological monitoring. Conclusions: This pilot study demonstrates that administering low MAC inhalational anaesthetics to facilitate evoked potential monitoring does not result in explicit awareness. However, larger studies are needed to verify this. The conduct of SSEP electrophysiological monitoring was satisfactory with the use of this

  13. [Voluntary changes of visual evoked potentials in cases with hysteria and/or simulation].

    Science.gov (United States)

    Manresa, M J; Bonaventura, I; Martínez, I; Gómez, L; Aguilar, M

    1996-03-01

    We report a 25-year-old woman with gradual loss of visual acuteness, during puerperium and blindness in fifteen days. Two months latter she remain steady. Visual evoked potentials using monocular checkerboard pattern-reversal, were abnormal. Clinical suspicion of voluntary alteration of VEP was considered. A second VEP exploration with binocular stimulation and maneuvers of distraction were carried out. Normal VEP were recorded. Deliberate alteration of the visual evoked potential should be considered in patients suspicious of hysteria or malingering.

  14. Evaluation of brain function in acute carbon monoxide poisoning with multimodality evoked potentials

    Energy Technology Data Exchange (ETDEWEB)

    He, Fengsheng; Liu, Xibao; Yang, Shi; Zhang, Shoulin (Institute of Occupational Medicine, Beijing (China)); Xu, Guanghua; Fang, Guangchai; Pan, Xiaowen (Navy Hospital, Beijing (China))

    1993-02-01

    The median nerve somatosensory evoked potentials (SEP), pattern reversal visual evoked potentials (VEP), and brain stem auditory evoked potentials (BAEP) were studied in 109 healthy adults and in 88 patients with acute carbon monoxide (CO) poisoning. The upper limits for normal values of peak and interpeak latencies of multimodalities of evoked potentials in the reference group were established by a stepwise multiple regression analysis. SEP changes selectively affecting N32 and N60 were found in 78.8% of patients. There was prolonged PI00 latency of VEP in 58.2% of the cases examined. The prevalence of BAEP abnormalities in comatose patients (36%) was significantly higher than that (8.6%) in conscious patients. BAEP abnormalities were most frequently seen in comatose patients who had diminished brain stem reflexes (77.8%). It has been found that a consistent abnormality involving N2O and subsequent peaks in SEP, a remarkable prolongation of PI00 latency in VEP, or a prolongation of Ill-V interpeak latency in BAEP as well as the reoccurrence of evoked potential abnormalities after initial recovery all indicate unfavorable outcomes in patients with acute CO poisoning. The multimodality evoked potentials have proved to be sensitive indicators in the evaluation of brain dysfunction and in the prediction of prognosis of acute CO poisoning and the development of delayed encephalopathy. 16 refs., 4 figs., 6 tabs.

  15. The strychnine-like action of curare and related compounds on the somatosensory evoked response of the rat cortex

    Science.gov (United States)

    Bhargava, V. K.; Meldrum, B. S.

    1969-01-01

    1. Drugs were applied to the cerebral cortex of rats anaesthetized with pentobarbitone and changes measured in the somatosensory primary evoked response. 2. Computer-derived averages of thirty-two consecutive responses yielded stable and consistent measurements of the potential changes comprising the evoked response, and comparable records from the opposite (non-drug treated) cortex provided an essential control for systemic actions of the drug. 3. The modifications produced by curare and strychnine were indistinguishable. The first positive wave (peak latency 7 msec) was unaltered; the second positive wave (peak latency 11·5 msec) was variably enhanced, and the first and second negative waves (peak latencies 16 and 40 msec) were replaced by a much larger negative wave (peak latency 22 msec). 4. The time of onset of the effect on the negative waves and the maximal amplitude attained by the abnormal negative wave were related to the log concentration of the drug used. Curare is approximately 10 times more potent than strychnine. 5. Toxiferine I, di-allylnortoxiferine and atropine also produced this effect but were less potent than strychnine. 6. Succinylcholine, dihydro-β-erythroidine and gallamine triethiodide did not produce this effect (in concentrations up to 10-3M). 7. The observations are consistent with an action of curare and strychnine on an intracortical cholinergic inhibitory system, but other possibilities including a “non-specific excitatory action” cannot be excluded. PMID:5824927

  16. Long-term potentiation (LTP) of human sensory-evoked potentials.

    Science.gov (United States)

    Kirk, Ian J; McNair, Nicolas A; Hamm, Jeffrey P; Clapp, Wesley C; Mathalon, Daniel H; Cavus, Idil; Teyler, Timothy J

    2010-09-01

    Long-term potentiation (LTP) is the principal candidate synaptic mechanism underlying learning and memory, and has been studied extensively at the cellular and molecular level in laboratory animals. Inquiry into the functional significance of LTP has been hindered by the absence of a human model as, until recently, LTP has only been directly demonstrated in humans in isolated cortical tissue obtained from patients undergoing surgery, where it displays properties identical to those seen in non-human preparations. In this brief review, we describe the results of paradigms recently developed in our laboratory for inducing LTP-like changes in visual-, and auditory-evoked potentials. We describe how rapid, repetitive presentation of sensory stimuli leads to a persistent enhancement of components of sensory-evoked potential in normal humans. Experiments to date, investigating the locus, stimulus specificity, and NMDA receptor dependence of these LTP-like changes suggest that they have the essential characteristics of LTP seen in experimental animals. The ability to elicit LTP from non-surgical patients will provide a human model system allowing the detailed examination of synaptic plasticity in normal subjects and may have future clinical applications in the assessment of cognitive disorders. Copyright © 2010 John Wiley & Sons, Ltd. For further resources related to this article, please visit the WIREs website. Copyright © 2010 John Wiley & Sons, Ltd.

  17. Long-Term Visuo-Gustatory Appetitive and Aversive Conditioning Potentiate Human Visual Evoked Potentials

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    Gert R. J. Christoffersen

    2017-09-01

    Full Text Available Human recognition of foods and beverages are often based on visual cues associated with flavors. The dynamics of neurophysiological plasticity related to acquisition of such long-term associations has only recently become the target of investigation. In the present work, the effects of appetitive and aversive visuo-gustatory conditioning were studied with high density EEG-recordings focusing on late components in the visual evoked potentials (VEPs, specifically the N2-P3 waves. Unfamiliar images were paired with either a pleasant or an unpleasant juice and VEPs evoked by the images were compared before and 1 day after the pairings. In electrodes located over posterior visual cortex areas, the following changes were observed after conditioning: the amplitude from the N2-peak to the P3-peak increased and the N2 peak delay was reduced. The percentage increase of N2-to-P3 amplitudes was asymmetrically distributed over the posterior hemispheres despite the fact that the images were bilaterally symmetrical across the two visual hemifields. The percentage increases of N2-to-P3 amplitudes in each experimental subject correlated with the subject’s evaluation of positive or negative hedonic valences of the two juices. The results from 118 scalp electrodes gave surface maps of theta power distributions showing increased power over posterior visual areas after the pairings. Source current distributions calculated from swLORETA revealed that visual evoked currents rose as a result of conditioning in five cortical regions—from primary visual areas and into the inferior temporal gyrus (ITG. These learning-induced changes were seen after both appetitive and aversive training while a sham trained control group showed no changes. It is concluded that long-term visuo-gustatory conditioning potentiated the N2-P3 complex, and it is suggested that the changes are regulated by the perceived hedonic valence of the US.

  18. Comparison of visual evoked potentials and retinal nerve fibre layer thickness in Alzheimer‘s disease

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    Robert eKromer

    2013-12-01

    Full Text Available IntroductionAlzheimer‘s disease is a long term progressive neurodegenerative disease and might affect the retinal nerve fibre layer thickness of the eye. There is increasing evidence that visual evoked potentials, which are an objective way to indicate visual field loss, might be affected by the disease as well.Material and Methods22 patients (mean age: 75.9 ± 6.1 years; 14 women with mild-to-moderate Alzheimer‘s disease and 22 sex-matched healthy patients were examined. We compared the use of visual evoked potentials and retinal nerve fibre layer thickness using latest high-resolution spectral domain optical coherence tomography with eye-tracking capabilities for optimised peripapillary scan centring for the first time in Alzheimer‘s disease patients.ResultsThe mean MMSE score was 22.59 ± 5.47 in the Alzheimer‘s disease group, and did not significantly correlate with the visual evoked potentials latencies. We found no significant difference between the visual evoked potentials latencies of the Alzheimer‘s disease patients and those of the control patients. No peripapillary sector of the retina had a retinal nerve fibre layer thickness significantly correlated with the visual evoked potentials latencies.DiscussionWe demonstrated that pattern visual evoked potentials did not show any significant correlation despite subtle loss in retinal nerve fibre layer thickness. It remains open whether additional flash visual evoked potentials combined with retinal nerve fibre layer thickness analysis may be useful in diagnosing Alzheimer‘s disease, particularly for mild-to-moderate stages of the disease.

  19. [The use of short-latency auditory evoked potentials in the diagnosis of acoustic neurinomas].

    Science.gov (United States)

    Baliazin, V A; Bakhtin, O M; Bu Khaled, Kh E; Filatova, V S

    1993-01-01

    The short-latent acoustic evoked potentials in patients with unilateral neurosensory hypoacusis due to the tumor of the acoustic nerve or other etiology were recorded. It was found that the patients had no potential in the diseased area in monaural sound stimulation, but binaural sound stimulation enabled these potentials to be recorded. With this, the short-latent acoustic evoked potentials in patients with verified neurinoma showed a reduction in the third wave to the point of its disappearance. Those in patients whose neurosensory hypoacusis were unassociated with the development of neoplasms in the area of the acoustic nerve involve the third wave whose magnitude did not differ from that recorded in the examinees with otologically normal hearing. The authors propose to measure the third wave of the short-latent acoustic evoked potential recorded in binaural sound stimulation as a possible screening of persons at a high risk for neurinoma among patients with unilateral neurosensory hypoacusis.

  20. [Peripheral and central somatosensory pathways and evoked cerebral potentials during aging (author's transl)].

    Science.gov (United States)

    Cheron, G; Desmedt, J E

    1980-01-01

    This study used electrical stimulation of the fingers and hands and evoked potentials to determine the functional state of the peripheral and central somatosensitive pathway in octogenarian subjects after very strict selection to exclude associated disease. The nerve fibers of the digital nerves were studied by recording the antidromic potential. Despite a marked reduction in the amplitude of this potential and an increase in latent period and duration, absolute and functional refractory periods were not increased with aging. Slowing in the rate of orthodromic conduction was demonstrated by the recording of nerve potentials and the spinal evoked potential. The amplitude of this evoked activity in the neck is significantly reduced in octogenarians. By contrast, the central transit of the somatosensory afferent impulses from the spinal cord to the cortex is remarkably well preserved. In addition, the amplitude of the parietal components of S.E.P. are significantly increased in the octogenarian.

  1. A comparison of auditory evoked potentials to acoustic beats and to binaural beats.

    Science.gov (United States)

    Pratt, Hillel; Starr, Arnold; Michalewski, Henry J; Dimitrijevic, Andrew; Bleich, Naomi; Mittelman, Nomi

    2010-04-01

    The purpose of this study was to compare cortical brain responses evoked by amplitude modulated acoustic beats of 3 and 6 Hz in tones of 250 and 1000 Hz with those evoked by their binaural beats counterparts in unmodulated tones to indicate whether the cortical processes involved differ. Event-related potentials (ERPs) were recorded to 3- and 6-Hz acoustic and binaural beats in 2000 ms duration 250 and 1000 Hz tones presented with approximately 1 s intervals. Latency, amplitude and source current density estimates of ERP components to beats-evoked oscillations were determined and compared across beat types, beat frequencies and base (carrier) frequencies. All stimuli evoked tone-onset components followed by oscillations corresponding to the beat frequency, and a subsequent tone-offset complex. Beats-evoked oscillations were higher in amplitude in response to acoustic than to binaural beats, to 250 than to 1000 Hz base frequency and to 3 Hz than to 6 Hz beat frequency. Sources of the beats-evoked oscillations across all stimulus conditions located mostly to left temporal lobe areas. Differences between estimated sources of potentials to acoustic and binaural beats were not significant. The perceptions of binaural beats involve cortical activity that is not different than acoustic beats in distribution and in the effects of beat- and base frequency, indicating similar cortical processing. Copyright 2010 Elsevier B.V. All rights reserved.

  2. Modulation of the N30 generators of the somatosensory evoked potentials by the mirror neuron system.

    Science.gov (United States)

    Cebolla, A M; Palmero-Soler, E; Dan, B; Cheron, G

    2014-07-15

    The N30 component of the somatosensory evoked potential is known to be modulated by sensory interference, motor action, movement ideation and observation. We introduce a new paradigm in which the observation task of another person's hand movement triggers the somatosensory stimulus, inducing the N30 response in participants. In order to identify the possible contribution of the mirror neuron network (MNN) to this early sensorimotor processing, we analyzed the N30 topography, the event-related spectral perturbation and the inter-trial coherence on single electroencephalogram (EEG) trials, and we applied swLORETA to localize the N30 sources implicated in the time-frequency domain at rest and during observation, as well as the generators differentiating these two contextual brain states. We found that N30 amplitude increase correlated with increased contralateral precentral alpha, frontal beta, and contralateral frontal gamma power spectrum, and with central and precentral alpha and parietal beta phase-locking of ongoing EEG signals. We demonstrate specific activation of the contralateral post-central and parietal cortex where the angular gyrus (BA39), an important MNN node, is implicated in this enhancement during observation. We conclude that this part of the MNN, involved in proprioceptive processing and more complex body-action representations, is already active prior to somatosensory input and may enhance N30. Copyright © 2014 Elsevier Inc. All rights reserved.

  3. Pattern-reversal visual evoked potentials as a diagnostic tool for ocular malingering.

    Science.gov (United States)

    Soares, Tarciana de Souza; Sacai, Paula Yuri; Berezovsky, Adriana; Rocha, Daniel Martins; Watanabe, Sung Eun Song; Salomão, Solange Rios

    2016-01-01

    To investigate the contributions of transient pattern-reversal visual evoked potentials in the diagnosis of ocular malingering at a Brazilian university hospital. Adult patients with suspected malingering in one or both eyes were referred for visual evoked potential testing. Data from patients' medical records were reviewed and analyzed retrospectively. Data analysis included the distance optotype visual acuity based on a ETDRS retro-illuminated chart and the transient pattern-reversal visual evoked potential parameters of latency (milliseconds) and amplitude (microvolts) for the P100 component, using checkerboards with visual subtenses of 15' and 60'. Motivations for malingering were noted. The 20 subjects included 11 (55%) women. Patient ages ranged from 21 to 61 years (mean= 45.05 ± 11.76 years; median= 49 years). In 8 patients (6 women), both eyes exhibited reduced visual acuity with normal pattern-reversal visually evoked potential parameters (pure malingerers). The remaining 12 patients (7 men) exhibited reduced vision in only 1 eye, with simulated reduced vision in the contralateral eye (exaggerators). Financial motivation was noted in 18 patients (9 men). Normal pattern-reversal visually evoked potential parameters with suspected ocular malingering were observed in a 20 patient cohort. This electrophysiological technique appeared to be useful as a measure of visual pathway integrity in this specific population.

  4. Predictability of painful stimulation modulates the somatosensory-evoked potential in the rat

    NARCIS (Netherlands)

    Schaap, M.W.H.; van Oostrom, H.; Doornenbal, A.; Baars, A.M.; Arndt, S.S.; Hellebrekers, L.J.

    2013-01-01

    Abstract Somatosensory-evoked potentials (SEPs) are used in humans and animals to increase knowledge about nociception and pain. Since the SEP in humans increases when noxious stimuli are administered unpredictably, predictability potentially influences the SEP in animals as well. To assess the

  5. Exploring the methods of data analysis in multifocal visual evoked potentials

    DEFF Research Database (Denmark)

    Malmqvist, Lasse; Santiago de Abreu, Lucimar; Fraser, C.

    2016-01-01

    Purpose: The multifocal visual evoked potential (mfVEP) provides a topographical assessment of visual function, which has already shown potential for use in patients with glaucoma and multiple sclerosis. However, the variability in mfVEP measurements has limited its broader application. The purpo...

  6. Effects of single cycle binaural beat duration on auditory evoked potentials.

    Science.gov (United States)

    Mihajloski, Todor; Bohorquez, Jorge; Özdamar, Özcan

    2014-01-01

    Binaural beat (BB) illusions are experienced as continuous central pulsations when two sounds with slightly different frequencies are delivered to each ear. It has been shown that steady-state auditory evoked potentials (AEPs) to BBs can be captured and investigated. The authors recently developed a new method of evoking transient AEPs to binaural beats using frequency modulated stimuli. This methodology was able to create single BBs in predetermined intervals with varying carrier frequencies. This study examines the effects of the BB duration and the frequency modulating component of the stimulus on the binaural beats and their evoked potentials. Normal hearing subjects were tested with a set of four durations (25, 50, 100, and 200 ms) with two stimulation configurations, binaural dichotic (binaural beats) and diotic (frequency modulation). The results obtained from the study showed that out of the given durations, the 100 ms beat, was capable of evoking the largest amplitude responses. The frequency modulation effect showed a decrease in peak amplitudes with increasing beat duration until their complete disappearance at 200 ms. Even though, at 200 ms, the frequency modulation effects were not present, the binaural beats were still perceived and captured as evoked potentials.

  7. Auditory Brain-Stem and Middle-and Long-Latency Evoked Potentials in Coma

    OpenAIRE

    Rosenberg, C; Wogensen, K; Starr, A

    1984-01-01

    Twenty-five patients in coma, each with a Glascow Coma Scale measure less than or equal to five, were studied within the first three days of hospitalization with auditory brain-stem and middle- and long-latency evoked potentials. Survival was related to the simultaneous preservation of long- and middle-latency and brain-stem evoked potentials. The preservation of just middle-latency and/or brain-stem components did not correlate with survival. However, if the group of patients in coma due to ...

  8. Multimodal evoked potentials follow up in multiple sclerosis patients under fingolimod therapy

    DEFF Research Database (Denmark)

    Iodice, R; Carotenuto, A; Dubbioso, R

    2016-01-01

    related to EDSS at baseline (t=-1), while MEP and total EP sum score were related to EDSS at all time points. CONCLUSION: Fingolimod is able to improve visual and somatosensory evoked potential in RR-MS patients even if clinical disability scale remains stable. VEP and SEP could give eloquent information...... patients examined 12months prior to initiation of fingolimod (t=-1), at treatment initiation (t=0) and 1year later (t=+1) were compared. Each EP (VEP, MEP, SEP) and EP sum score, a global evoked potential score as the sum score of the each EP score was evaluated and correlated with Expanded Disability...

  9. Conduction velocity of the human spinothalamic tract as assessed by laser evoked potentials

    DEFF Research Database (Denmark)

    Cruccu, G.; Iannetti, G. D.; Agostino, R.

    2000-01-01

    To study the conduction velocity of the spinothalamic tract (STT) we delivered CO2 laser pulses, evoking pinprick sensations, to the skin overlying the vertebral spinous processes at different spinal levels from C5 to T10 and recorded evoked potentials (LEPs) in 15 healthy human subjects....... These stimuli yielded large-amplitude vertex potentials consisting of a negative wave at a peak latency of about 200 ms followed by a positive wave at a peak latency of about 300 ms. The mean conduction velocity of the STT was 21 m/s, i.e. higher than the reported velocity of the corresponding primary sensory...

  10. touché is required for touch evoked generator potentials within vertebrate sensory neurons

    Science.gov (United States)

    Low, Sean E.; Ryan, Joel; Sprague, Shawn M.; Hirata, Hiromi; Cui, Wilson W.; Zhou, Weibin; Hume, Richard I.; Kuwada, John Y.; Saint-Amant, Louis

    2010-01-01

    The process by which light-touch in vertebrates is transformed into an electrical response in cutaneous mechanosensitive neurons is a largely unresolved question. To address this question we undertook a forward genetic screen in zebrafish (Danio rerio) to identify mutants exhibiting abnormal touch-evoked behaviors, despite the presence of sensory neurons and peripheral neurites. One family, subsequently named touché, was found to harbor a recessive mutation which produced offspring that were unresponsive to light-touch, but responded to a variety of other sensory stimuli. The optogenetic activation of motor behaviors by touché mutant sensory neurons expressing ChannelRhodopsin-2 suggested that the synaptic output of sensory neurons was intact, consistent with a defect in sensory neuron activation. To explore sensory neuron activation we developed an in vivo preparation permitting the precise placement of a combined electrical and tactile stimulating probe upon eGFP positive peripheral neurites. In wild type larva electrical and tactile stimulation of peripheral neurites produced action potentials detectable within the cell body. In a subset of these sensory neurons an underlying generator potential could be observed in response to subthreshold tactile stimuli. A closer examination revealed that the amplitude of the generator potential was proportional to the stimulus amplitude. When assayed touché mutant sensory neurons also responded to electrical stimulation of peripheral neurites similar to wild type larvae, however tactile stimulation of these neurites failed to uncover a subset of sensory neurons possessing generator potentials. These findings suggest that touché is required for generator potentials, and that generator potentials underlie responsiveness to light-touch in zebrafish. PMID:20631165

  11. Primary Generators of Visually Evoked Field Potentials Recorded in the Macaque Auditory Cortex.

    Science.gov (United States)

    Kajikawa, Yoshinao; Smiley, John F; Schroeder, Charles E

    2017-10-18

    Prior studies have reported "local" field potential (LFP) responses to faces in the macaque auditory cortex and have suggested that such face-LFPs may be substrates of audiovisual integration. However, although field potentials (FPs) may reflect the synaptic currents of neurons near the recording electrode, due to the use of a distant reference electrode, they often reflect those of synaptic activity occurring in distant sites as well. Thus, FP recordings within a given brain region (e.g., auditory cortex) may be "contaminated" by activity generated elsewhere in the brain. To determine whether face responses are indeed generated within macaque auditory cortex, we recorded FPs and concomitant multiunit activity with linear array multielectrodes across auditory cortex in three macaques (one female), and applied current source density (CSD) analysis to the laminar FP profile. CSD analysis revealed no appreciable local generator contribution to the visual FP in auditory cortex, although we did note an increase in the amplitude of visual FP with cortical depth, suggesting that their generators are located below auditory cortex. In the underlying inferotemporal cortex, we found polarity inversions of the main visual FP components accompanied by robust CSD responses and large-amplitude multiunit activity. These results indicate that face-evoked FP responses in auditory cortex are not generated locally but are volume-conducted from other face-responsive regions. In broader terms, our results underscore the caution that, unless far-field contamination is removed, LFPs in general may reflect such "far-field" activity, in addition to, or in absence of, local synaptic responses. SIGNIFICANCE STATEMENT Field potentials (FPs) can index neuronal population activity that is not evident in action potentials. However, due to volume conduction, FPs may reflect activity in distant neurons superimposed upon that of neurons close to the recording electrode. This is problematic as the

  12. Primary Generators of Visually Evoked Field Potentials Recorded in the Macaque Auditory Cortex

    Science.gov (United States)

    Smiley, John F.; Schroeder, Charles E.

    2017-01-01

    Prior studies have reported “local” field potential (LFP) responses to faces in the macaque auditory cortex and have suggested that such face-LFPs may be substrates of audiovisual integration. However, although field potentials (FPs) may reflect the synaptic currents of neurons near the recording electrode, due to the use of a distant reference electrode, they often reflect those of synaptic activity occurring in distant sites as well. Thus, FP recordings within a given brain region (e.g., auditory cortex) may be “contaminated” by activity generated elsewhere in the brain. To determine whether face responses are indeed generated within macaque auditory cortex, we recorded FPs and concomitant multiunit activity with linear array multielectrodes across auditory cortex in three macaques (one female), and applied current source density (CSD) analysis to the laminar FP profile. CSD analysis revealed no appreciable local generator contribution to the visual FP in auditory cortex, although we did note an increase in the amplitude of visual FP with cortical depth, suggesting that their generators are located below auditory cortex. In the underlying inferotemporal cortex, we found polarity inversions of the main visual FP components accompanied by robust CSD responses and large-amplitude multiunit activity. These results indicate that face-evoked FP responses in auditory cortex are not generated locally but are volume-conducted from other face-responsive regions. In broader terms, our results underscore the caution that, unless far-field contamination is removed, LFPs in general may reflect such “far-field” activity, in addition to, or in absence of, local synaptic responses. SIGNIFICANCE STATEMENT Field potentials (FPs) can index neuronal population activity that is not evident in action potentials. However, due to volume conduction, FPs may reflect activity in distant neurons superimposed upon that of neurons close to the recording electrode. This is

  13. Multi-channel motor evoked potential monitoring during anterior cervical discectomy and fusion

    Directory of Open Access Journals (Sweden)

    Dong-Gun Kim

    Full Text Available Objectives: Anterior cervical discectomy and fusion (ACDF surgery is the most common surgical procedure for the cervical spine with low complication rate. Despite the potential prognostic benefit, intraoperative neurophysiological monitoring (IONM, a method for detecting impending neurological compromise, is not routinely used in ACDF surgery. The present study aimed to identify the potential benefits of monitoring multi-channel motor evoked potentials (MEPs during ACDF surgery. Methods: We retrospectively reviewed 200 consecutive patients who received IONM with multi-channel MEPs and somatosensory evoked potentials (SSEPs. On average, 9.2 muscles per patient were evaluated under MEP monitoring. Results: The rate of MEP change during surgery in the multi-level ACDF group was significantly higher than the single-level group. Two patients from the single-level ACDF group (1.7% and four patients from the multi-level ACDF group (4.9% experienced post-operative motor deficits. Multi-channel MEPs monitoring during single and multi-level ACDF surgery demonstrated higher sensitivity, specificity, positive predictive and negative predictive value than SSEP monitoring. Conclusions: Multi-channel MEP monitoring might be beneficial for the detection of segmental injury as well as long tract injury during single- and multi-level ACDF surgery. Significance: This is first large scale study to identify the usefulness of multi-channel MEPs in monitoring ACDF surgery. Keywords: Disc disease, Somatosensory evoked potentials, Intraoperative neurophysiological monitoring, Motor evoked potentials, Anterior cervical discectomy and fusion

  14. Evaluation of cochlear implant benefit with auditory cortical evoked potentials.

    NARCIS (Netherlands)

    Beynon, A.J.; Snik, A.F.M.; Broek, P. van den

    2002-01-01

    Endogenous P300 and exogenous slow vertex potentials were obtained with tone and speech stimuli in a group of five children using a cochlear implant (CI) with poor speech recognition (group A) and compared with those from another group of five children using a CI with good speech recognition (group

  15. [The use of thresholds of electrically evoked short-latent auditory potentials for the adjustment of the speech processors in the patients undergoing cochlear implantation].

    Science.gov (United States)

    Kuzovkov, V E; Gaufman, V E; Klyachko, D S; Pudov, V I

    2016-01-01

    The objective of the present study was to determine the thresholds of electrically evoked short-latent auditory potentials by the mathematical method and to elucidate the relationship between these parameters and the subjective maximally comfortable levels in the patients undergoing cochlear implantation. The electrically evoked short-latent auditory potentials were recorded in two groups of patients with different stimulation frequency (17 and 43 Hz). The use of the mathematical method of linear regression of the amplitude (peak V) growth function for determining the thresholds of electrically evoked short-latent auditory potentials has a number of advantages over visual detection of the threshold level. To increase the reliability of the data obtained, low stimulation frequencies need to be used when recording electrically evoked short-latent auditory potentials (17 Hz). The calculated thresholds of electrically evoked short-latent auditory potentials can be used to estimate the subjective maximally comfortable levels for the adjustment of the speech processors when it is impossible to register electrically induced stapedial reflexes and electrically induced total action potentials of the auditory nerve in the patients having cochlear implants.

  16. Glass pipette-carbon fiber microelectrodes for evoked potential recordings

    Directory of Open Access Journals (Sweden)

    Moraes M.F.D.

    1997-01-01

    Full Text Available Current methods for recording field potentials with tungsten electrodes make it virtually impossible to use the same recording electrode also as a lesioning electrode, for example for histological confirmation of the recorded site, because the lesioning procedure usually wears off the tungsten tip. Therefore, the electrode would have to be replaced after each lesioning procedure, which is a very high cost solution to the problem. We present here a low cost, easy to make, high quality glass pipette-carbon fiber microelectrode that shows resistive, signal/noise and electrochemical coupling advantages over tungsten electrodes. Also, currently used carbon fiber microelectrodes often show problems with electrical continuity, especially regarding electrochemical applications using a carbon-powder/resin mixture, with consequent low performance, besides the inconvenience of handling such a mixture. We propose here a new method for manufacturing glass pipette-carbon fiber microelectrodes with several advantages when recording intracerebral field potentials

  17. Vestibular-evoked myogenic potentials in miniature pigs

    Directory of Open Access Journals (Sweden)

    Xi Shi

    2016-06-01

    Conclusion: The latencies and thresholds of VEMPs recorded from the neck extensor muscle and the masseter muscle appear to be comparable in normal adult Bama miniature pigs, although the amplitude recorded from the neck extensor muscle seems to be higher than that from the masseter muscle. However, because of their usually relatively superficial and easily accessible location, as well as their large volume and strong contractions, masseter muscles may be better target muscles for recording myogenic potentials.

  18. Absence of both auditory evoked potentials and auditory percepts dependent on timing cues.

    Science.gov (United States)

    Starr, A; McPherson, D; Patterson, J; Don, M; Luxford, W; Shannon, R; Sininger, Y; Tonakawa, L; Waring, M

    1991-06-01

    An 11-yr-old girl had an absence of sensory components of auditory evoked potentials (brainstem, middle and long-latency) to click and tone burst stimuli that she could clearly hear. Psychoacoustic tests revealed a marked impairment of those auditory perceptions dependent on temporal cues, that is, lateralization of binaural clicks, change of binaural masked threshold with changes in signal phase, binaural beats, detection of paired monaural clicks, monaural detection of a silent gap in a sound, and monaural threshold elevation for short duration tones. In contrast, auditory functions reflecting intensity or frequency discriminations (difference limens) were only minimally impaired. Pure tone audiometry showed a moderate (50 dB) bilateral hearing loss with a disproportionate severe loss of word intelligibility. Those auditory evoked potentials that were preserved included (1) cochlear microphonics reflecting hair cell activity; (2) cortical sustained potentials reflecting processing of slowly changing signals; and (3) long-latency cognitive components (P300, processing negativity) reflecting endogenous auditory cognitive processes. Both the evoked potential and perceptual deficits are attributed to changes in temporal encoding of acoustic signals perhaps occurring at the synapse between hair cell and eighth nerve dendrites. The results from this patient are discussed in relation to previously published cases with absent auditory evoked potentials and preserved hearing.

  19. Early visual evoked potentials are modulated by eye position in humans induced by whole body rotations

    Directory of Open Access Journals (Sweden)

    Petit Laurent

    2004-09-01

    Full Text Available Abstract Background To reach and grasp an object in space on the basis of its image cast on the retina requires different coordinate transformations that take into account gaze and limb positioning. Eye position in the orbit influences the image's conversion from retinotopic (eye-centered coordinates to an egocentric frame necessary for guiding action. Neuroimaging studies have revealed eye position-dependent activity in extrastriate visual, parietal and frontal areas that is along the visuo-motor pathway. At the earliest vision stage, the role of the primary visual area (V1 in this process remains unclear. We used an experimental design based on pattern-onset visual evoked potentials (VEP recordings to study the effect of eye position on V1 activity in humans. Results We showed that the amplitude of the initial C1 component of VEP, acknowledged to originate in V1, was modulated by the eye position. We also established that putative spontaneous small saccades related to eccentric fixation, as well as retinal disparity cannot explain the effects of changing C1 amplitude of VEP in the present study. Conclusions The present modulation of the early component of VEP suggests an eye position-dependent activity of the human primary visual area. Our findings also evidence that cortical processes combine information about the position of the stimulus on the retinae with information about the location of the eyes in their orbit as early as the stage of primary visual area.

  20. Cholinergic pairing with visual activation results in long-term enhancement of visual evoked potentials.

    Directory of Open Access Journals (Sweden)

    Jun Il Kang

    Full Text Available Acetylcholine (ACh contributes to learning processes by modulating cortical plasticity in terms of intensity of neuronal activity and selectivity properties of cortical neurons. However, it is not known if ACh induces long term effects within the primary visual cortex (V1 that could sustain visual learning mechanisms. In the present study we analyzed visual evoked potentials (VEPs in V1 of rats during a 4-8 h period after coupling visual stimulation to an intracortical injection of ACh analog carbachol or stimulation of basal forebrain. To clarify the action of ACh on VEP activity in V1, we individually pre-injected muscarinic (scopolamine, nicotinic (mecamylamine, alpha7 (methyllycaconitine, and NMDA (CPP receptor antagonists before carbachol infusion. Stimulation of the cholinergic system paired with visual stimulation significantly increased VEP amplitude (56% during a 6 h period. Pre-treatment with scopolamine, mecamylamine and CPP completely abolished this long-term enhancement, while alpha7 inhibition induced an instant increase of VEP amplitude. This suggests a role of ACh in facilitating visual stimuli responsiveness through mechanisms comparable to LTP which involve nicotinic and muscarinic receptors with an interaction of NMDA transmission in the visual cortex.

  1. Cortical evoked potentials to an auditory illusion: Binaural beats

    OpenAIRE

    Pratt, H; Starr, A; Michalewski, HJ; Dimitrijevic, A; Bleich, N; Mittelman, N

    2009-01-01

    Objective: To define brain activity corresponding to an auditory illusion of 3 and 6 Hz binaural beats in 250 Hz or 1000 Hz base frequencies, and compare it to the sound onset response. Methods: Event-Related Potentials (ERPs) were recorded in response to unmodulated tones of 250 or 1000 Hz to one ear and 3 or 6 Hz higher to the other, creating an illusion of amplitude modulations (beats) of 3 Hz and 6 Hz, in base frequencies of 250 Hz and 1000 Hz. Tones were 2000 ms in duration and presented...

  2. A comparison of auditory evoked potentials to acoustic beats and to binaural beats

    OpenAIRE

    Pratt, H; Starr, A; Michalewski, HJ; Dimitrijevic, A; Bleich, N; Mittelman, N

    2010-01-01

    The purpose of this study was to compare cortical brain responses evoked by amplitude modulated acoustic beats of 3 and 6 Hz in tones of 250 and 1000 Hz with those evoked by their binaural beats counterparts in unmodulated tones to indicate whether the cortical processes involved differ. Event-related potentials (ERPs) were recorded to 3- and 6-Hz acoustic and binaural beats in 2000 ms duration 250 and 1000 Hz tones presented with approximately 1 s intervals. Latency, amplitude and source cur...

  3. Effect of surgery on sensory threshold and somatosensory evoked potentials after skin stimulation

    DEFF Research Database (Denmark)

    Lund, C; Hansen, O B; Kehlet, H

    1990-01-01

    We have studied the effect of surgical injury on cutaneous sensitivity and somatosensory evoked potentials (SSEP) to dermatomal electrical stimulation in 10 patients undergoing hysterectomy. Forty-eight hours after surgery, sensory threshold increased from 2.2 (SEM 0.3) mA to 4.4 (1.1) mA (P less...

  4. Analysis of gender based differences in auditory evoked potentials among healthy elderly population

    Directory of Open Access Journals (Sweden)

    Sharat Gupta

    2014-01-01

    Full Text Available Background: Influence of gender on auditory evoked potentials is contentious. Although there are quite a few studies documenting the gender as an influencing factor on auditory evoked potentials in younger subjects, but there is a lack of similar studies among elderly population. The present study was conducted to find out the pattern of gender based differences in auditory evoked potentials among healthy elderly subjects. Materials and Methods: A cross-sectional study was conducted on age matched, healthy males (n = 35 and females (n = 34, aged 50-70 years. The measures included latencies of waves I-V and interpeak latencies (IPL I-III, III-V and I-V separately for both ears. Data was analyzed statistically using Students unpaired t-test, using Statistical Package for Social Sciences software v13.0. Results: The values of all the latencies and IPL for both the ears were non-significantly higher (P > 0.05 in males as compared to females. These results may be attributed to the differences in head circumference between both the genders and to the changed hormonal milieu of sex hormones after menopause. Conclusions: Statistical insignificance of latencies among male and female elderly subjects excludes gender as an influencing factor on auditory evoked potentials in this age group.

  5. Visual, auditory, and somatosensorial evoked potentials in early and late treated adolescents with phenylketonuria.

    Science.gov (United States)

    Leuzzi, V; Cardona, F; Antonozzi, I; Loizzo, A

    1994-11-01

    Pattern reversal visual, auditory, and somatosensorial evoked potentials were recorded in two groups of phenylketonuric (PKU) adolescents after protracted exposition to high concentrations of phenylalanine following diet discontinuation. The first group consisted of 11 early treated (before age 3 months) PKU patients (ET-PKU); the second group consisted of 11 late detected (after age 8 months), symptomatic, PKU subjects (LT-PKU). Despite the relevant lag between the two groups in mental development and neurological status, no clear-cut difference in evoked potentials could be detected. Only the wave I latency of the brainstem auditory evoked potentials (BAEPs) was significantly shorter in ET- versus LT-PKU children. The P100 latency, I-V interpeak latency (IPL), and I-III IPL seem to discriminate the less severe form of PKU (ET-PKU type 3) from the most severe forms, ET-PKU type 1 plus 2 and LT-PKU. No correlations were found between clinical, biochemical, and neurophysiological parameters. The present data suggest that evoked potentials technique is of limited sensitivity in detecting central nervous system (CNS) alterations in PKU adolescents after diet discontinuation.

  6. Proprioceptive evoked potentials in man: cerebral responses to changing weight loads on the hand

    DEFF Research Database (Denmark)

    Arnfred, S; He, Chen; Eder, D

    2000-01-01

    , P190, and a single negative frontal Fz/N70 component. We conclude that a brisk change of a hand held load elicits a significant evoked potential (EP) unlike the electrical somato-sensory EP (SEP). The stimulus is perceived as applied force. For this reason we call it a proprioceptive EP (PEP...

  7. Muscle potentials evoked by magnetic stimulation of the sciatic nerve in unilateral sciatic nerve dysfunction

    NARCIS (Netherlands)

    Van Soens, I.; Struys, M. M. R. F.; Van Ham, L. M. L.

    Magnetic stimulation of the sciatic nerve and subsequent recording of the muscle-evoked potential (MEP) was performed in eight dogs and three cats with unilateral sciatic nerve dysfunction. Localisation of the lesion in the sciatic nerve was based on the history, clinical neurological examination

  8. Effects of diazepam on auditory evoked potentials of rats elicited in a ten-tone paradigm

    NARCIS (Netherlands)

    Jongsma, M.L.A.; Rijn, C.M. van; Schaijk, W.J. van; Coenen, A.M.L.; Dirksen, R.

    2000-01-01

    The effect of diazepam on sensory gating was studied in rats, by measuring diazepam effects on Auditory Evoked Potentials (AEPs) elicited in a ten-tone paradigm. Trains of 10 repetitive tone-pip stimuli were presented. Rats (n=8) received 4 mg.kg-1 diazepam s.c. or vehicle, counterbalanced over two

  9. The influence of diazepam on the electroencephalogram-evoked potential interrelation in rats

    NARCIS (Netherlands)

    Jongsma, M.L.A.; Rijn, C.M. van; Egmond, J. van; Schaijk, W.J. van; Sambeth, A.; Coenen, A.M.L.

    2000-01-01

    Though being a sedative increases b-activity in the electroencephalogram (EEG). Diazepam also affects auditory evoked potentials (AEPs). We investigated if the effect of diazepam on AEPs could be ascribed to its b-increasing effect. Eight rats received vehicle and diazepam counterbalanced. AEPs were

  10. Research on pattern reversal visual evoked potential of children with spastic cerebral palsy

    Directory of Open Access Journals (Sweden)

    Lu Li

    2015-07-01

    Full Text Available AIM: To explore the judgment of pattern reversal visual evoked potential on visual function and injured part of children with spastic cerebral palsy.METHODS: There were two groups in this study. 30 children with spastic cerebral palsy(quadriplegia: 15, diplegia: 15were selected as observation group, while 30 normal children were selected as control group with randomized controlled trial. The changes of half-view and full-view incubation period and amplitude were observed by pattern reversal visual evoked potential.RESULTS: Full-view pattern reversal visual evoked potential: the P100 incubation period of the observation group was 113.55±8.14ms, and the P100 amplitude was 23.08±15.41μV. The P100 incubation period of the control group was 105.05±5.58ms, and the P100 amplitude was 31.65±7.37μV. From the comparison on P100 incubation and P100 amplitude between two groups, the difference was statistically significant(PP>0.05. Compared to the control group, each eye and each view latency of observation group were higher, the difference was statistically significant(PCONCLUSION: Pattern reversal visual evoked potential can help people to understand the visual impairment and injury of children with spastic cerebral palsy in order to identify the abnormal children and early intervention.

  11. Effect of epidural 0.25% bupivacaine on somatosensory evoked potentials to dermatomal stimulation

    DEFF Research Database (Denmark)

    Lund, C; Hansen, O B; Kehlet, H

    1989-01-01

    The effect of lumbar epidural analgesia with similar volumes (about 25 ml) of 0.25% and 0.5% bupivacaine on early (less than 0.5 seconds) somatosensory evoked potentials (SEPs) to electrical stimulation of the S1, L1, and T10 dermatomes was examined in two groups of ten patients. Level of sensory...

  12. Effects of etidocaine administered epidurally on changes in somatosensory evoked potentials after dermatomal stimulation

    DEFF Research Database (Denmark)

    Lund, C; Hansen, O B; Kehlet, H

    1991-01-01

    The effect of lumbar epidural anesthesia with similar volumes (approximately 20 ml) of 1% and 1.5% etidocaine on early (less than 0.5 seconds) somatosensory evoked potentials (SEPs) to electrical stimulation of the S1, L1, and T10 dermatomes was examined in two groups of ten patients...

  13. Unmasking of an early laser evoked potential by a point localization task

    DEFF Research Database (Denmark)

    Valeriani, M.; Restuccia, D.; Le Pera, D.

    2000-01-01

    Objectives: The investigation of the CO2 laser evoked potential (LEP) modifications following a point localization task. Methods: LEPs were recorded from 10 healthy subjects in two different conditions. (1) Task condition: laser stimuli were shifted among 3 different locations on the right hand d...

  14. A Steady State Visually Evoked Potential Investigation of Memory and Ageing

    Science.gov (United States)

    Macpherson, Helen; Pipingas, Andrew; Silberstein, Richard

    2009-01-01

    Old age is generally accompanied by a decline in memory performance. Specifically, neuroimaging and electrophysiological studies have revealed that there are age-related changes in the neural correlates of episodic and working memory. This study investigated age-associated changes in the steady state visually evoked potential (SSVEP) amplitude and…

  15. Rhythmic context influences the auditory evoked potentials of musicians and nonmusicians

    NARCIS (Netherlands)

    Jongsma, M.L.A.; Desain, P.W.M.; Honing, H.J.

    2004-01-01

    In this study, we investigated how rhythms are processed in the brain by measuring both behaviourally obtained ratings and auditory evoked potentials (AEPs) from the EEG. We presented probe beats on seven positions within a test bar. Two bars of either a duple- or triple meter rhythm preceded probe

  16. Feasibility and performance evaluation of generating and recording visual evoked potentials using ambulatory Bluetooth based system.

    Science.gov (United States)

    Ellingson, Roger M; Oken, Barry

    2010-01-01

    Report contains the design overview and key performance measurements demonstrating the feasibility of generating and recording ambulatory visual stimulus evoked potentials using the previously reported custom Complementary and Alternative Medicine physiologic data collection and monitoring system, CAMAS. The methods used to generate visual stimuli on a PDA device and the design of an optical coupling device to convert the display to an electrical waveform which is recorded by the CAMAS base unit are presented. The optical sensor signal, synchronized to the visual stimulus emulates the brain's synchronized EEG signal input to CAMAS normally reviewed for the evoked potential response. Most importantly, the PDA also sends a marker message over the wireless Bluetooth connection to the CAMAS base unit synchronized to the visual stimulus which is the critical averaging reference component to obtain VEP results. Results show the variance in the latency of the wireless marker messaging link is consistent enough to support the generation and recording of visual evoked potentials. The averaged sensor waveforms at multiple CPU speeds are presented and demonstrate suitability of the Bluetooth interface for portable ambulatory visual evoked potential implementation on our CAMAS platform.

  17. Effects of stimulus duration on gustatory evoked potentials

    DEFF Research Database (Denmark)

    Rotvel, Camilla Arndal; Møller, Stine; Kivisaar, Kätlin

    The objective of the present study was to investigate the effect of tastant stimulus duration on the brain response. The brain response was measured by electroencephalography (EEG) which measures neural processes with high temporal resolution and may therefore complement sensory panel assessments....... 19 normal-tasting subjects (10 females, mean age ± sd: 27 ± 3) were stimulated with aqueous 0.5g/L sucralose in between continuous periods of non-chlorinated tap water to avoid somatosensory onsets. The sucralose stimulus duration was either short (~0.6s) or long (~4s) and presented in random...... sequence with 60 repetitions. The stimuli were delivered to the center of the tongue apex innervated by chorda tympani nerve. Brain response was recorded with 128 electrodes and the gustatory event related potential (GEP) was estimated by coherent averaging of all artefact free epochs. Focusing on the FC5...

  18. Do resting brain dynamics predict oddball evoked-potential?

    Directory of Open Access Journals (Sweden)

    Lee Tien-Wen

    2011-11-01

    Full Text Available Abstract Background The oddball paradigm is widely applied to the investigation of cognitive function in neuroscience and in neuropsychiatry. Whether cortical oscillation in the resting state can predict the elicited oddball event-related potential (ERP is still not clear. This study explored the relationship between resting electroencephalography (EEG and oddball ERPs. The regional powers of 18 electrodes across delta, theta, alpha and beta frequencies were correlated with the amplitude and latency of N1, P2, N2 and P3 components of oddball ERPs. A multivariate analysis based on partial least squares (PLS was applied to further examine the spatial pattern revealed by multiple correlations. Results Higher synchronization in the resting state, especially at the alpha spectrum, is associated with higher neural responsiveness and faster neural propagation, as indicated by the higher amplitude change of N1/N2 and shorter latency of P2. None of the resting quantitative EEG indices predict P3 latency and amplitude. The PLS analysis confirms that the resting cortical dynamics which explains N1/N2 amplitude and P2 latency does not show regional specificity, indicating a global property of the brain. Conclusions This study differs from previous approaches by relating dynamics in the resting state to neural responsiveness in the activation state. Our analyses suggest that the neural characteristics carried by resting brain dynamics modulate the earlier/automatic stage of target detection.

  19. Auditory evoked potential P300 in adults: reference values.

    Science.gov (United States)

    Didoné, Dayane Domeneghini; Garcia, Michele Vargas; Oppitz, Sheila Jacques; Silva, Thalisson Francisco Finamôr da; Santos, Sinéia Neujahr Dos; Bruno, Rúbia Soares; Filha, Valdete Alves Valentins Dos Santos; Cóser, Pedro Luis

    2016-01-01

    To establish reference intervals for cognitive potential P300 latency using tone burst stimuli. This study involved 28 participants aged between 18 and 59 years. P300 recordings were performed using a two-channel device (Masbe, Contronic). Electrode placement was as follows: Fpz (ground electrode), Cz (active electrode), M1 and M2 (reference electrodes). Intensity corresponded to 80 dB HL and frequent and rare stimulus frequencies to 1,000Hz and 2,000Hz, respectively. Stimuli were delivered binaurally. Mean age of participants was 35 years. Average P300 latency was 305ms. Maximum acceptable P300 latency values of 362.5ms (305 + 2SD 28.75) were determined for adults aged 18 to 59 years using the protocol described. Estabelecer valores de referência para a latência do potencial cognitivo P300 com estímulos tone burst. Participaram do estudo 28 indivíduos entre 18 e 59 anos. O registro do P300 foi realizado no equipamento Masbe da marca Contronic. Os eletrodos foram fixados nas posições Fpz (eletrodo terra), Cz (eletrodo ativo), M1 e M2 (eletrodos referência). A intensidade foi de 80 dB NA. A frequência do estímulo frequente foi de 1.000Hz e a do estímulo raro de 2.000Hz. Os estímulos foram apresentados na forma binaural. A média de idade dos indivíduos foi de 35 anos. A média de latência para P300 de 305ms. Usando o protocolo descrito, o valor máximo de latência aceitáveis para P300 foram de 362,5ms (305 + 2DP 28,75) na faixa etária do adulto de 18 a 59 anos.

  20. Inhibitory and potentiating influences of glycine on N-methyl-D-aspartate-evoked dopamine release from cultured rat mesencephalic cells

    International Nuclear Information System (INIS)

    Mount, H.; Quirion, R.; Chaudieu, I.; Boksa, P.

    1991-01-01

    In the presence of 1.2 mM Mg2+, glycine (30-100 microM) inhibited [3H]dopamine ([3H]DA) release stimulated by N-methyl-D-aspartate (NMDA), in fetal rat mesencephalic cell cultures. Strychnine (1 microM) blocked the inhibitory effect of 100 microM glycine, indicating an action via strychnine-sensitive inhibitory glycine receptors. A higher concentration of strychnine (100 microM), by itself, inhibited NMDA-evoked [3H]DA release in the presence or absence of Mg2+. Spontaneous [3H]DA release and [3H]DA release stimulated by kainate and quisqualate were unaffected by glycine (less than or equal to 100 microM) or strychnine (less than or equal to 100 microM), indicating that glycine and strychnine modulatory effects are only associated with the NMDA receptor subtype. [3H]DA release evoked by K+ (56 mM) was unaffected by glycine (less than or equal to 100 microM) but was attenuated by a high concentration of strychnine (100 microM). In the absence of exogenous Mg2+, glycine (30-100 microM) potentiated NMDA-evoked [3H]DA release by a strychnine-insensitive mechanism. A selective antagonist of the NMDA-associated glycine receptor, 7-chlorokynurenate (10 microM), attenuated NMDA-evoked [3H]DA release in the absence of Mg2+. The effect of 10 microM 7-chlorokynurenate was overcome by 1 microM glycine. Also, when tested in the presence of 1.2 nM Mg2+ and 1 microM strychnine, 100 microM 7-chlorokynurenate inhibited NMDA-evoked [3H]DA release, and this antagonism was overcome by 30 to 100 microM glycine. These results indicate that two distinct glycine receptors modulate NMDA-stimulated [3H]DA release from mesencephalic cells in culture. Manipulation of extracellular Mg2+ permits the differentiation of a strychnine-sensitive glycine response (inhibition of NMDA-evoked [3H]DA release) from a strychnine-insensitive glycine response

  1. Intermediate Latency-Evoked Potentials of Multimodal Cortical Vestibular Areas: Galvanic Stimulation

    Directory of Open Access Journals (Sweden)

    Stefan Kammermeier

    2017-11-01

    Full Text Available IntroductionHuman multimodal vestibular cortical regions are bilaterally anterior insulae and posterior opercula, where characteristic vestibular-related cortical potentials were previously reported under acoustic otolith stimulation. Galvanic vestibular stimulation likely influences semicircular canals preferentially. Galvanic stimulation was compared to previously established data under acoustic stimulation.Methods14 healthy right-handed subjects, who were also included in the previous acoustic potential study, showed normal acoustic and galvanic vestibular-evoked myogenic potentials. They received 2,000 galvanic binaural bipolar stimuli for each side during EEG recording.ResultsVestibular cortical potentials were found in all 14 subjects and in the pooled data of all subjects (“grand average” bilaterally. Anterior insula and posterior operculum were activated exclusively under galvanic stimulation at 25, 35, 50, and 80 ms; frontal regions at 30 and 45 ms. Potentials at 70 ms in frontal regions and at 110 ms at all of the involved regions could also be recorded; these events were also found using acoustic stimulation in our previous study.ConclusionGalvanic semicircular canal stimulation evokes specific potentials in addition to those also found with acoustic otolith stimulation in identically located regions of the vestibular cortex. Vestibular cortical regions activate differently by galvanic and acoustic input at the peripheral sensory level.SignificanceDifferential effects in vestibular cortical-evoked potentials may see clinical use in specific vertigo disorders.

  2. [Analysis of pudendal nerve somatosensory evoked potentials in the diagnosis of neurogenic impotence].

    Science.gov (United States)

    Salinas Casado, J; Chamorro, M V; Samblas García, R; Esteban Fuertes, M; Aristizábal Agudelo, J M; Delgado Martín, J A; Blázquez Izquierdo, J; Resel Estévez, L

    1997-06-01

    To determine the utility of the somatosensorial evoked potentials of the pudental nerve in the diagnosis of neurogenic impotence. 129 patients with impotence were evaluated by physical examination and neuroandrologic profile. The neuroandrologic profile was assessed by bulbocavernous electromyography, determination of S2-S4 evoked potentials, analysis of the somatosensorial potentials of the pudendal nerve, cavernous smooth muscle electromyography (SPACE), sympathetic skin response and cystometry. The patients with a neurologic lesion presented a significantly longer latency time of the somatosensorial potentials than those with no neurologic lesion. The sensitivity of the somatosensorial potentials was 63% and the specificity was 98%. The sensitivity could be enhanced without significantly lowering specificity by taking 49 msec as the upper limit of normal values in latency time. The determination of the voluntary anal control in the diagnosis of neurogenic impotence was found to have a high specificity (93%), but a low sensitivity (42%). The determination of the somatosensorial potentials, unlike other techniques, could allow diagnosis of lesions of the suprasacral inneveration in the evaluation of neurogenic impotence. The evoked somatosensorial potentials of the pudendal nerve and physical examination have the inconvenience of their low sensitivity in regard to the diagnosis of neurogenic lesion in impotence, mainly because some conditions only affect the peripheral autonomic innervation and the somatic element is spared.

  3. Direct motor evoked potentials and cortical mapping using the NIM® nerve monitoring system: A technical note.

    Science.gov (United States)

    Bharadwaj, Suparna; Haji, Faizal; Hebb, Matthew; Chui, Jason

    2017-04-01

    Motor evoked potentials (MEPs) are commonly used to prevent neurological injury when operating in close proximity to the motor cortex or corticospinal pathway. We report a novel application of the NIM® nerve monitoring system (Medtronic@ NIM response 3.0) for intraoperative direct cortical (dc)-MEPs monitoring. A 69-year-old female patient presented with a 4month history of progressive left hemiparesis resulting from a large right sided posterior frontal meningioma that abutted and compressed the motor cortex. Motor cortical mapping and MEPs were indicated. The patient was anesthetized and maintained on total intravenous anesthetics. Compound muscle action potentials (CMAP) of the right upper limb were monitored using the NIM system. After a craniotomy was performed, we first used the Ojemann stimulator (monopolar) for dc-stimulation and then switched to use the monopolar nerve stimulator probe of the NIM system. The CMAP response was successfully elicited using the NIM stimulating probe (pulse width=250s, train frequency=7pulses/s, current=20mA). A gross total resection of the tumor was achieved with intermittent cortical mapping of MEPs. There were no intraoperative complications and the patient's motor function was preserved after the surgery. In this case, we reported the successful use of the NIM nerve monitoring system to elicit dc-MEPs under general anesthesia. The advantages of using this system include a simple set up and application, neurosurgeon familiarity, wide availability and lower cost. dc-MEPs can be achieved using the NIM system. We conclude that the NIM nerve monitoring system is a feasible alternative to standard neurophysiological monitoring systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Vestibular Dysfunctions in Cochlear Implant Patients; A Vestibular Evoked Myogenic Potential Study

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    Masoud Motasaddi Zarandy

    2011-12-01

    Full Text Available Background and Aim: Vestibular evoked myogenic potential in response to click or short tone burst stimuli have been used as a clinical test for distinguish saccule and inferior vestibular nerve diseases. Different studies show that cochlear implant could have inverse effects on vestibular structures. We aimed to investigate vestibular evoked myogenic potential in unilateral cochlear implanted individuals in compare to normal individuals.Methods: Thirty-three unilateral cochlear implanted patients (mean age 19.96 years and 30 normal hearing individuals (mean age 24-27 years as control group were enrolled in this cross- sectional study. Absolute latencies and amplitudes of myogenic potential responses were measured and compared in both groups.Results: Myogenic potential recorded in both ears of all controls were normal. No response could be recorded in 16 patients (48.48% from both ears. In three patients, responses were recorded in both ears though the amplitude of waves was reduced in implanted ear. Unilateral response could be recorded in 14 patients only in their non-implanted ear.Conclusion: Vestibular evoked myogenic potential test is a useful tool for assessing saccular function in cochlear implant patients. Damages of osseous spiral lamina and basilar membrane after cochlear implantation could result in dysfunctions of vestibular organs specially saccule. It seems that saccule could be easily damaged after cochlear implantation. This would cause absence or reduced amplitudes in myogenic potential.

  5. [Patterns of action potential firing in cortical neurons of neonatal mice and their electrophysiological property].

    Science.gov (United States)

    Furong, Liu; Shengtian, L I

    2016-05-25

    To investigate patterns of action potential firing in cortical heurons of neonatal mice and their electrophysiological properties. The passive and active membrane properties of cortical neurons from 3-d neonatal mice were observed by whole-cell patch clamp with different voltage and current mode. Three patterns of action potential firing were identified in response to depolarized current injection. The effects of action potential firing patterns on voltage-dependent inward and outward current were found. Neurons with three different firing patterns had different thresholds of depolarized current. In the morphology analysis of action potential, the three type neurons were different in rise time, duration, amplitude and threshold of the first action potential evoked by 80 pA current injection. The passive properties were similar in three patterns of action potential firing. These results indicate that newborn cortical neurons exhibit different patterns of action potential firing with different action potential parameters such as shape and threshold.

  6. Simultaneously-evoked auditory potentials (SEAP): A new method for concurrent measurement of cortical and subcortical auditory-evoked activity.

    Science.gov (United States)

    Slugocki, Christopher; Bosnyak, Daniel; Trainor, Laurel J

    2017-03-01

    Recent electrophysiological work has evinced a capacity for plasticity in subcortical auditory nuclei in human listeners. Similar plastic effects have been measured in cortically-generated auditory potentials but it is unclear how the two interact. Here we present Simultaneously-Evoked Auditory Potentials (SEAP), a method designed to concurrently elicit electrophysiological brain potentials from inferior colliculus, thalamus, and primary and secondary auditory cortices. Twenty-six normal-hearing adult subjects (mean 19.26 years, 9 male) were exposed to 2400 monaural (right-ear) presentations of a specially-designed stimulus which consisted of a pure-tone carrier (500 or 600 Hz) that had been amplitude-modulated at the sum of 37 and 81 Hz (depth 100%). Presentation followed an oddball paradigm wherein the pure-tone carrier was set to 500 Hz for 85% of presentations and pseudo-randomly changed to 600 Hz for the remaining 15% of presentations. Single-channel electroencephalographic data were recorded from each subject using a vertical montage referenced to the right earlobe. We show that SEAP elicits a 500 Hz frequency-following response (FFR; generated in inferior colliculus), 80 (subcortical) and 40 (primary auditory cortex) Hz auditory steady-state responses (ASSRs), mismatch negativity (MMN) and P3a (when there is an occasional change in carrier frequency; secondary auditory cortex) in addition to the obligatory N1-P2 complex (secondary auditory cortex). Analyses showed that subcortical and cortical processes are linked as (i) the latency of the FFR predicts the phase delay of the 40 Hz steady-state response, (ii) the phase delays of the 40 and 80 Hz steady-state responses are correlated, and (iii) the fidelity of the FFR predicts the latency of the N1 component. The SEAP method offers a new approach for measuring the dynamic encoding of acoustic features at multiple levels of the auditory pathway. As such, SEAP is a promising tool with which to study how

  7. Steady-State Somatosensory Evoked Potential for Brain-Computer Interface–Present and Future

    Directory of Open Access Journals (Sweden)

    Sangtae eAhn

    2016-01-01

    Full Text Available Brain-computer interface (BCI performance has achieved continued improvement over recent decades, and sensorimotor rhythm-based BCIs that use motor function have been popular subjects of investigation. However, it remains problematic to introduce them to the public market because of their low reliability. As an alternative resolution to this issue, visual-based BCIs that use P300 or steady-state visually evoked potentials seem promising; however, the inherent visual fatigue that occurs with these BCIs may be unavoidable. For these reasons, steady-state somatosensory evoked potential (SSSEP BCIs, which are based on tactile selective attention, have gained increasing attention recently. These may reduce the fatigue induced by visual attention and overcome the low reliability of motor activity. In this literature survey, recent findings on SSSEP and its methodological uses in BCI are reviewed. Further, existing limitations of SSSEP BCI and potential future directions for the technique are discussed.

  8. Fast detection of unexpected sound intensity decrements as revealed by human evoked potentials.

    Directory of Open Access Journals (Sweden)

    Heike Althen

    Full Text Available The detection of deviant sounds is a crucial function of the auditory system and is reflected by the automatically elicited mismatch negativity (MMN, an auditory evoked potential at 100 to 250 ms from stimulus onset. It has recently been shown that rarely occurring frequency and location deviants in an oddball paradigm trigger a more negative response than standard sounds at very early latencies in the middle latency response of the human auditory evoked potential. This fast and early ability of the auditory system is corroborated by the finding of neurons in the animal auditory cortex and subcortical structures, which restore their adapted responsiveness to standard sounds, when a rare change in a sound feature occurs. In this study, we investigated whether the detection of intensity deviants is also reflected at shorter latencies than those of the MMN. Auditory evoked potentials in response to click sounds were analyzed regarding the auditory brain stem response, the middle latency response (MLR and the MMN. Rare stimuli with a lower intensity level than standard stimuli elicited (in addition to an MMN a more negative potential in the MLR at the transition from the Na to the Pa component at circa 24 ms from stimulus onset. This finding, together with the studies about frequency and location changes, suggests that the early automatic detection of deviant sounds in an oddball paradigm is a general property of the auditory system.

  9. Brain state-dependence of electrically evoked potentials monitored with head-mounted electronics.

    Science.gov (United States)

    Richardson, Andrew G; Fetz, Eberhard E

    2012-11-01

    Inferring changes in brain connectivity is critical to studies of learning-related plasticity and stimulus-induced conditioning of neural circuits. In addition, monitoring spontaneous fluctuations in connectivity can provide insight into information processing during different brain states. Here, we quantified state-dependent connectivity changes throughout the 24-h sleep-wake cycle in freely behaving monkeys. A novel, head-mounted electronic device was used to electrically stimulate at one site and record evoked potentials at other sites. Electrically evoked potentials (EEPs) revealed the connectivity pattern between several cortical sites and the basal forebrain. We quantified state-dependent changes in the EEPs. Cortico-cortical EEP amplitude increased during slow-wave sleep, compared to wakefulness, while basal-cortical EEP amplitude decreased. The results demonstrate the utility of using portable electronics to document state-dependent connectivity changes in freely behaving primates.

  10. Somatosensory evoked potentials (S.E.P.) in slow pathological compression of the spinal cord.

    Science.gov (United States)

    Rossini, P M; Greco, F; David, P; Pisano, L; De Palma, L; Tonali, P

    1979-12-01

    Somatosensory evoked potentials (S.E.P.) were used to examine twelve patients who had slow compressive lesions of the spinal cord (ten cases of spondylotic myelopathy, one neurinoma, one metastasis of a vertebral body). 73 per cent of the recordings were found to be abnormally reduced in amplitude, and/or showed prolonged latency times aa regards the primary and secondary complex. Patients with a clinical lesion of the dorsal column showed a clear reduction in amplitude in the recordings (sometimes coupled with slowed latency), especially in the primary complex. Patients with symptoms indicative of an injury to the ventrolateral region of the spinal cord showed tracings with alterations most of all related to the secondary complex. In 76 per cent of cases, the somatosensory evoked potentials were in accordance with the level of the compression, the degree of invalidity, and the clinical picture.

  11. [Contribution of the vestibular evoked myogenic potentials to the study of the vestibular neuritis].

    Science.gov (United States)

    Lesmas Navarro, María José; Pérez Garrigues, Herminio; Morera Pérez, Constantino; Piqueras, Adelina

    2009-01-01

    Until recently, the only tests available to provide information about vestibular function were caloric and kinetic tests, which only give us information about the external semicircular canal and the superior vestibular nerve. In recent years the development of vestibular evoked myogenic potentials has allowed us to assess the saccule and the inferior vestibular nerve. Our aim is, by studying the caloric test results as well as the vestibular evoked myogenic potentials in patients with Vestibular Neuritis, to determine whether they have involvement of the superior, inferior or both vestibular nerves. Retrospective study of 9 patients with Vestibular Neuritis admitted to a tertiary care hospital. We studied them by means of anamnesis, otoneurological clinical examination, caloric test and vestibular evoked myogenic potentials. Their clinical progress after admission and any residual instability were also studied. Women were more affected (66.6 %) than males. The mean age for presentation of the disease was 53.8 +/- 14.0 years. Hospital stays lasted for 5.7 +/- 3.2 days. After their crises, they suffered from instability for 122 +/- 114 days. Four cases were diagnosed as Complete Vestibular Neuritis and five as Superior Vestibular Neuritis. P13 wave latency was normal in all cases. There were no differences between the groups in terms of the length of hospital stay nor residual instability. Nowadays, vestibular evoked myogenic potentials make it possible to advance further in the study of Vestibular Neuritis. Complete and superior vestibular neuritis are much more frequent than inferior vestibular neuritis. Clinical behaviour is similar in the sub-types found.

  12. Auditory and Visual Evoked Potentials as a Function of Sleep Deprivation and Irregular Sleep

    Science.gov (United States)

    1989-08-15

    1984). Evoked potentials and P300 during sensory conditioning in autistic children . Annals of the New York Academy of Sciences, 425, 362-369. McKenna...results from ERPs collected immediately following arousals from sleep is also questionable. In addition, subjects were either children , narcoleptics...137-145. Broughton, R. (1968). Sleep disorders : Disorders of arousal? Science, 159, 1070-1078. Broughton, R. (1975). Biorhythmic variations in

  13. [Effects of sevoflurane and propofol on evoked potentials during neurosurgical anesthesia].

    Science.gov (United States)

    Nakagawa, Itsuo; Hidaka, Syozo; Okada, Hironori; Kubo, Takashi; Okamura, Kenta; Kato, Takahiro

    2006-06-01

    The effect of anesthetics on somatosensory evoked potential (SEP) and auditory brain stem response (ABR) has been a subject of intense reseach over the last two decades. In fact, volatile anesthetics have been repeatedly shown to decrease cortical amplitude in a dose-dependent fashion but the information regarding the effect of propofol is incomplete. The purpose of this study was to compare the effects of sevoflurane and propofol on evoked potentials during comparable depth of anesthesia guided by bispectral index (BIS). Forty four patients scheduled for neurosurgery were studied. Anesthesia was maintained with intravenous propofol using target controlled infusion (TCI). We measured the change of amplitude and latency of SEP(N20-P25), ABR (V wave) and visual evoked potential (VEP: P100) at three sets of sevoflurane (0%, 1%, 2%) or propofol concentrations (effect site concentration of 1.5, 2.0, 3.0 microug x ml(-1)). BIS monitor was used to measure relative depth of hypnosis. With increasing concentrations of sevoflurane (0, 1% and 2%), SEP showed dose-related reduction in its amplitude, ABR produced less marked changes and VEP showed a significant reduction at 1%. VEP at the propofol concentration of 3.0 microg x ml(-1) was decreased significantly compared with the amplitude at 1.5 microg x ml(-1) concentration. No significant change was observed with SEP and ABR during the change of propofol dosages. BIS values were almost the same with each anesthetics. VEP was most strongly affected with anesthetics, and ABR showed less marked influence of sevoflurane and propofol. Propofol based TIVA technique would induce less change in evoked potentials than sevoflurane.

  14. Effect of extradural morphine on somatosensory evoked potentials to dermatomal stimulation

    DEFF Research Database (Denmark)

    Lund, C; Selmar, P; Hansen, O B

    1987-01-01

    The effect of the extradural (L2-3) administration of morphine 6 mg on early (less than 0.5 s) somatosensory evoked cortical potentials (SEP) to electrical stimulation of the L1- and S1-dermatomes was examined in eight patients. Extradural morphine did not influence SEP amplitude. SEP latency did...... not change, except for a minor increase in the latencies of the onset and the P2 components following S1 stimulation....

  15. Motor Evoked Potentials of Trunk Muscles in Traumatic Brain Injury Patients

    OpenAIRE

    Seo, Min-Ho; Park, Sung-Hee; Ko, Myoung-Hwan; Seo, Jeong-Hwan

    2011-01-01

    Objective To evaluate the motor innervation of trunk muscles in traumatic brain injury patients. Method Twenty patients (12 men and 8 women) with traumatic brain injury were enrolled in this study. Their mean age was 41 years. Motor evoked potentials (MEPs) were performed on the motor cortex. Electromyographic activities were recorded from the bilateral rectus abdominis muscles, the external oblique abdominal muscles, and the 4th and 9th thoracic erector spinae muscles. The onset latency and ...

  16. Evoked potential correlates of selective attention with multi-channel auditory inputs

    Science.gov (United States)

    Schwent, V. L.; Hillyard, S. A.

    1975-01-01

    Ten subjects were presented with random, rapid sequences of four auditory tones which were separated in pitch and apparent spatial position. The N1 component of the auditory vertex evoked potential (EP) measured relative to a baseline was observed to increase with attention. It was concluded that the N1 enhancement reflects a finely tuned selective attention to one stimulus channel among several concurrent, competing channels. This EP enhancement probably increases with increased information load on the subject.

  17. Proprioceptive evoked potentials in man: cerebral responses to changing weight loads on the hand

    DEFF Research Database (Denmark)

    Arnfred, S; He, Chen; Eder, D

    2000-01-01

    , P190, and a single negative frontal Fz/N70 component. We conclude that a brisk change of a hand held load elicits a significant evoked potential (EP) unlike the electrical somato-sensory EP (SEP). The stimulus is perceived as applied force. For this reason we call it a proprioceptive EP (PEP......). Further studies of the PEP are needed to assess the influence of load manipulations and of muscle contraction and to explore the effect of attentional manipulation....

  18. The Middle Latency Response (MLR) and Steady State Evoked Potential (SSEP) in Neonates.

    Science.gov (United States)

    1985-05-01

    transplacental infections inducing pre-mature labor, low Apgar scores, neonatal asphyxia , respiratory distress syndrome, acidosis, ototoxic...TYPE OF REPORT A PERIOD COVERED The Middle Latency Response (MLR) and Steady ’YWggfl/DISSERTATION State Evoked Potential (SSEP) in Neonates :- G...Wright-Patterson AFB OH 45433 RESEARCH TITLE: The MLR and SSEP In Neonates AUTHOR: Robert C. Fifer RESEARCH ASSESSMENT QUESTIONS: 1. Did this research

  19. Clinical Utility and Limitations of Intraoperative Monitoring of Visual Evoked Potentials

    OpenAIRE

    Luo, Yeda; Regli, Luca; Bozinov, Oliver; Sarnthein, Johannes

    2015-01-01

    OBJECTIVES During surgeries that put the visual pathway at risk of injury, continuous monitoring of the visual function is desirable. However, the intraoperative monitoring of the visual evoked potential (VEP) is not yet widely used. We evaluate here the clinical utility of intraoperative VEP monitoring. METHODS We analyzed retrospectively 46 consecutive surgeries in 2011-2013. High luminance stimulating devices delivered flash stimuli on the closed eyelid during intravenous anesthesia. We...

  20. Temporal processing and long-latency auditory evoked potential in stutterers

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    Raquel Prestes

    Full Text Available Abstract Introduction: Stuttering is a speech fluency disorder, and may be associated with neuroaudiological factors linked to central auditory processing, including changes in auditory processing skills and temporal resolution. Objective: To characterize the temporal processing and long-latency auditory evoked potential in stutterers and to compare them with non-stutterers. Methods: The study included 41 right-handed subjects, aged 18-46 years, divided into two groups: stutterers (n = 20 and non-stutters (n = 21, compared according to age, education, and sex. All subjects were submitted to the duration pattern tests, random gap detection test, and long-latency auditory evoked potential. Results: Individuals who stutter showed poorer performance on Duration Pattern and Random Gap Detection tests when compared with fluent individuals. In the long-latency auditory evoked potential, there was a difference in the latency of N2 and P3 components; stutterers had higher latency values. Conclusion: Stutterers have poor performance in temporal processing and higher latency values for N2 and P3 components.

  1. [Clinical characterization of audiometric and vestibular evoked myogenic potentials in patients with large vestibular aqueduct syndrome].

    Science.gov (United States)

    Wu, Jun; Wang, Jinling; Xie, Juan; Han, Liping; Gao, Lei

    2010-01-01

    To investigate the clinical and diagnostic characteristics of audiometric findings and vestibular-evoked myogenic potentials in patients with large vestibular aqueduct syndrome (LVAS). Thirty LVAS subjects (60 ears) recruited received pure tone audiometry, acoustic immittance, auditory brain stem responses (ABRs), distortion-product otoacoustic emission (DPOAE), Vestibular evoked myogenic potentials (VEMP) and caloric test, and the diagnostic significance of the results was analyzed. All 30 cases (60 ears) showed progressive and fluctuating hearing loss, while 16 cases experienced dizziness when hearing fluctuated. Most of our cases showed sensorineural hearing loss, and 47 ears (94.0%) showed air-bone gap in the low frequencies, with mean gaps of (43 +/- 17) dB HL at 250 Hz, (33 +/- 18) dB HL at 500 Hz, in which the middle ear function showed normal. The acoustically evoked short latency negative response (ASNR) with medium latency (3.06 +/- 0.52) ms was elicited from 18 ears (64.3%). The mean amplitude of vestibular evoked myogenic potentials (VEMP) of 42 ears was (147.10 +/- 107.55) microv, and the threshold of VEMP of 19 ears was 75 dB nHL, of 7 ears was 65 dB nHL. Characteristics of hearing performance, such as progressive and fluctuating hearing loss, air-bone gap at the low frequencies with normal middle ears, the ASNR, and increased amplitude and decreased threshold of the VEMPs, will help clinicians make initial diagnosis of LVAS, and provide a reference for further imaging examination.

  2. Auditory fear conditioning modifies steady-state evoked potentials in the rat inferior colliculus.

    Science.gov (United States)

    Lockmann, André Luiz Vieira; Mourão, Flávio Afonso Gonçalves; Moraes, Marcio Flávio Dutra

    2017-08-01

    The rat inferior colliculus (IC) is a major midbrain relay for ascending inputs from the auditory brain stem and has been suggested to play a key role in the processing of aversive sounds. Previous studies have demonstrated that auditory fear conditioning (AFC) potentiates transient responses to brief tones in the IC, but it remains unexplored whether AFC modifies responses to sustained periodic acoustic stimulation-a type of response called the steady-state evoked potential (SSEP). Here we used an amplitude-modulated tone-a 10-kHz tone with a sinusoidal amplitude modulation of 53.7 Hz-as the conditioning stimulus (CS) in an AFC protocol (5 CSs per day in 3 consecutive days) while recording local field potentials (LFPs) from the IC. In the preconditioning session ( day 1 ), the CS elicited prominent 53.7-Hz SSEPs. In the training session ( day 2 ), foot shocks occurred at the end of each CS (paired group) or randomized in the inter-CS interval (unpaired group). In the test session ( day 3 ), SSEPs markedly differed from preconditioning in the paired group: in the first two trials the phase to which the SSEP coupled to the CS amplitude envelope shifted ~90°; in the last two trials the SSEP power and the coherence of SSEP with the CS amplitude envelope increased. LFP power decreased in frequency bands other than 53.7 Hz. In the unpaired group, SSEPs did not change in the test compared with preconditioning. Our results show that AFC causes dissociated changes in the phase and power of SSEP in the IC. NEW & NOTEWORTHY Local field potential oscillations in the inferior colliculus follow the amplitude envelope of an amplitude-modulated tone, originating a neural response called the steady-state evoked potential. We show that auditory fear conditioning of an amplitude-modulated tone modifies two parameters of the steady-state evoked potentials in the inferior colliculus: first the phase to which the evoked oscillation couples to the amplitude-modulated tone shifts

  3. Evaluation of Visual Evoked Potentials in Patient with Angelmans Syndrome - Case Report

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    Tatjana Knezevic

    2013-06-01

    Full Text Available Background: Angelman syndrome (AS is a genetic disorder with varying degrees of neurological impairment. It is often associated with ocular involvement. Case Report: We present a child diagnosed with AS who had a deletion on the short arm of chromosome 15. The child seemed to be happy, with developmental delay, speech problem, and altering strabismus. To assess the potential presence and degree of damage in the visual pathway, we recorded monocular flash visual evoked potentials (VEPs. Our results revealed the presence of severe central afferent dysfunction in both optical pathways. Conclusion: VEPs can be used in patients with AS and visual disturbances to assess the integrity of the visual system.

  4. Laser-evoked potential habituation and central sensitization symptoms in childhood migraine.

    Science.gov (United States)

    de Tommaso, Marina; Sciruicchio, Vittorio; Ricci, Katia; Montemurno, Anna; Gentile, Francesco; Vecchio, Eleonora; Barbaro, Maria Grazia Foschino; Simeoni, Michele; Goffredo, Marvita; Livrea, Paolo

    2016-04-01

    Few studies have addressed central sensitization symptoms and pain processing in childhood migraine. Our aims were to examine pain sensitivity and responses, including habituation, evoked by CO2 laser stimuli (laser-evoked potentials (LEPs)) in a cohort of children with migraine compared to non-migraine controls and to determine the correlation between LEP features and signs of central sensitization. Thirty-five patients 8-15 years of age with migraines without aura were evaluated during the inter-critical phase and were compared to 17 controls. LEPs were analyzed, and their main features were correlated with clinical symptoms including allodynia and pericranial tenderness. The laser-evoked pain threshold was lower and the N2P2 vertex complex amplitude was higher in children with migraines. Furthermore, habituation of vertex waves of LEPs clearly showed a tendency toward progressive amplitude enhancement in the migraine group. Acute allodynia and inter-critical pericranial tenderness correlated with trigeminal LEP features, particularly with the abnormal habituation pattern. Abnormalities of pain processing and symptoms of central sensitization appear to be characteristics of children with migraine. Reduced habituation and progressive amplification of cortical responses to laser stimuli indicate an overactive nociceptive system at the onset of migraine, and this hyperactivity may subtend allodynia and pericranial tenderness. Future prospective trials may aid in the early identification of clinical phenotypes that display a tendency to develop into the chronic form of migraine, warranting a timely therapeutic approach. © International Headache Society 2015.

  5. Cortical somatosensory-evoked potentials during spine surgery in patients with neuromuscular and idiopathic scoliosis under propofol-remifentanil anaesthesia

    NARCIS (Netherlands)

    Hermanns, H.; Lipfert, P.; Meier, S.; Jetzek-Zader, M.; Krauspe, R.; Stevens, M. F.

    2007-01-01

    BACKGROUND: Intraoperative monitoring of the spinal cord via cortical somatosensory-evoked potentials (SSEP) is a routine during spinal surgery. However, especially in neuromuscular scoliosis, the reliability of cortical SSEP has been questioned. Therefore, we compared the feasibility of cortical

  6. Flash visual evoked potentials in patients with periventricular leucomalacia in children less than 1 year of age

    OpenAIRE

    Jitendra Jethani; Monika Jethani

    2013-01-01

    Background and Aim: Children with periventricular leucomalacia (PVL) are known to have visual impairment of various forms starting from reduced vision, field defects, congnitive problems, and problems with hand eye coordination. There is very scant data/literature on the visual evoked potentials (VEPs) at an early age in children with PVL. We did a study to evaluate the flash visual evoked potentials (fVEPs) in children with PVL less than 1 year of age. Materials and Methods: A total of nine ...

  7. Ocular vestibular evoked myogenic potential in patients with benign paroxysmal positional vertigo

    Directory of Open Access Journals (Sweden)

    Mozhgan Masoom

    2014-06-01

    Full Text Available Background and Aim: Since utricle is the main damaged organ in benign paroxysmal positional vertigo (BPPV, ocular vestibular evoked myogenic potential (oVEMP may be an appropriate method to evaluate the utricule dysfunction and the effect of disease recurrence rate on it. This study aimed to record myogenic potential in patients with benign paroxysmal positional vertigo.Methods: In a cross-sectional study, ocular myogenic potential was recorded in 25 healthy subjects and 20 patients with benign paroxysmal positional vertigo using 500 Hz-tone bursts (95 dB nHL.Results: In the affected ear, mean amplitude was lower and mean threshold was higher than those in the unaffected ear and in the normal group (p<0.05. Mean amplitude asymmetry ratio of patients was more than the healthy subjects (p0.05. Frequencies of abnormal responses in the affected ears were higher than in unaffected ears and in the normal group (p<0.05. Furthermore, the patients with recurrent vertigo showed more abnormalities than the patients with non-recurrent (p=0.030.Conclusion: In the recurrent benign paroxysmal positional vertigo, ocular vestibular evoked myogenic potential showed more damage in the utricle, suggesting this response could be used to evaluate the patients with benign paroxysmal positional vertigo.

  8. The cortical spatiotemporal correlate of otolith stimulation: Vestibular evoked potentials by body translations.

    Science.gov (United States)

    Ertl, M; Moser, M; Boegle, R; Conrad, J; Zu Eulenburg, P; Dieterich, M

    2017-07-15

    The vestibular organ senses linear and rotational acceleration of the head during active and passive motion. These signals are necessary for bipedal locomotion, navigation, the coordination of eye and head movements in 3D space. The temporal dynamics of vestibular processing in cortical structures have hardly been studied in humans, let alone with natural stimulation. The aim was to investigate the cortical vestibular network related to natural otolith stimulation using a hexapod motion platform. We conducted two experiments, 1. to estimate the sources of the vestibular evoked potentials (VestEPs) by means of distributed source localization (n=49), and 2. to reveal modulations of the VestEPs through the underlying acceleration intensity (n=24). For both experiments subjects were accelerated along the main axis (left/right, up/down, fore/aft) while the EEG was recorded. We were able to identify five VestEPs (P1, N1, P2, N2, P3) with latencies between 38 and 461 ms as well as an evoked beta-band response peaking with a latency of 68 ms in all subjects and for all acceleration directions. Source localization gave the cingulate sulcus visual (CSv) area and the opercular-insular region as the main origin of the evoked potentials. No lateralization effects due to handedness could be observed. In the second experiment, area CSv was shown to be integral in the processing of acceleration intensities as sensed by the otolith organs, hinting at its potential role in ego-motion detection. These robust VestEPs could be used to investigate the mechanisms of inter-regional interaction in the natural context of vestibular processing and multisensory integration. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. [Forensic application of brainstem auditory evoked potential in patients with brain concussion].

    Science.gov (United States)

    Zheng, Xing-Bin; Li, Sheng-Yan; Huang, Si-Xing; Ma, Ke-Xin

    2008-12-01

    To investigate changes of brainstem auditory evoked potential (BAEP) in patients with brain concussion. Nineteen patients with brain concussion were studied with BAEP examination. The data was compared to the healthy persons reported in literatures. The abnormal rate of BAEP for patients with brain concussion was 89.5%. There was a statistically significant difference between the abnormal rate of patients and that of healthy persons (Pconcussion was 73.7%, indicating dysfunction of the brainstem in those patients. BAEP might be helpful in forensic diagnosis of brain concussion.

  10. Steady State Visual Evoked Potential Based Brain-Computer Interface for Cognitive Assessment

    DEFF Research Database (Denmark)

    Westergren, Nicolai; Bendtsen, Rasmus L.; Kjær, Troels W.

    2016-01-01

    decline is important. Cognitive decline may be detected using fullyautomated computerized assessment. Such systems will provide inexpensive and widely available screenings of cognitive ability. The aim of this pilot study is to develop a real time steady state visual evoked potential (SSVEP) based brain......-computer interface (BCI) for neurological cognitive assessment. It is intended for use by patients who suffer from diseases impairing their motor skills, but are still able to control their gaze. Results are based on 11 healthy test subjects. The system performance have an average accuracy of 100% ± 0%. The test...

  11. Cortical evoked potentials in response to rapid balloon distension of the rectum and anal canal

    DEFF Research Database (Denmark)

    Haas, S; Brock, C; Krogh, K

    2014-01-01

    healthy women received 30 RBDs in the rectum and the anal canal at intensities corresponding to sensory and unpleasantness thresholds, and response was recorded as cortical evoked potentials (CEPs) in 64-channels. The anal canal stimulations at unpleasantness level were repeated after 4 min to test...... the within-day reproducibility. CEPs were averaged, and to overcome latency variation related to jitter the spectral content of single sweeps was also computed. KEY RESULTS: Repeated stimulation of the anal canal generated CEPs with similar latencies but smaller amplitudes compared to those from the rectum...

  12. Simulation of action potential propagation in plants.

    Science.gov (United States)

    Sukhov, Vladimir; Nerush, Vladimir; Orlova, Lyubov; Vodeneev, Vladimir

    2011-12-21

    Action potential is considered to be one of the primary responses of a plant to action of various environmental factors. Understanding plant action potential propagation mechanisms requires experimental investigation and simulation; however, a detailed mathematical model of plant electrical signal transmission is absent. Here, the mathematical model of action potential propagation in plants has been worked out. The model is a two-dimensional system of excitable cells; each of them is electrically coupled with four neighboring ones. Ion diffusion between excitable cell apoplast areas is also taken into account. The action potential generation in a single cell has been described on the basis of our previous model. The model simulates active and passive signal transmission well enough. It has been used to analyze theoretically the influence of cell to cell electrical conductivity and H(+)-ATPase activity on the signal transmission in plants. An increase in cell to cell electrical conductivity has been shown to stimulate an increase in the length constant, the action potential propagation velocity and the temperature threshold, while the membrane potential threshold being weakly changed. The growth of H(+)-ATPase activity has been found to induce the increase of temperature and membrane potential thresholds and the reduction of the length constant and the action potential propagation velocity. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. Development of somatosensory-evoked potentials in foetal sheep: effects of betamethasone.

    Science.gov (United States)

    Anegroaie, P; Frasch, M G; Rupprecht, S; Antonow-Schlorke, I; Müller, T; Schubert, H; Witte, O W; Schwab, M

    2017-05-01

    Antenatal glucocorticoids are used to accelerate foetal lung maturation in babies threatened with premature labour. We examined the influence of glucocorticoids on functional and structural maturation of the central somatosensory pathway in foetal sheep. Somatosensory-evoked potentials (SEP) reflect processing of somatosensory stimuli. SEP latencies are determined by afferent stimuli transmission while SEP amplitudes reveal cerebral processing. After chronic instrumentation of foetal sheep, mothers received saline (n = 9) or three courses of betamethasone (human equivalent dose of 2 × 110 μg kg -1 betamethasone i.m. 24 h apart, n = 12) at 0.7, 0.75 and 0.8 of gestational age. Trigeminal SEP were evoked prior to, 4 and 24 h after each injection and at 0.8 of gestational age before brains were histologically processed. Somatosensory-evoked potentials were already detectable at 0.7 of gestation age. The early and late responses N20 and N200 were the only reproducible peaks over the entire study period. With advancing gestational age, SEP latencies decreased but amplitudes remained unchanged. Acutely, betamethasone did not affect SEP latencies and amplitudes 4 and 24 h following administration. Chronically, betamethasone delayed developmental decrease in the N200 but not N20 latency by 2 weeks without affecting amplitudes. In parallel, betamethasone decreased subcortical white matter myelination but did not affect network formation and synaptic density in the somatosensory cortex. Somatosensory stimuli are already processed by the foetal cerebral cortex at the beginning of the third trimester. Subsequent developmental decrease in SEP latencies suggests ongoing maturation of afferent sensory transmission. Antenatal glucocorticoids affect structural and functional development of the somatosensory system with specific effects at subcortical level. © 2016 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

  14. Participation of MT3 melatonin receptors in the synergistic effect of melatonin on cytotoxic and apoptotic actions evoked by chemotherapeutics.

    Science.gov (United States)

    Pariente, Roberto; Bejarano, Ignacio; Espino, Javier; Rodríguez, Ana B; Pariente, José A

    2017-11-01

    Melatonin has antitumor activity via several mechanisms including its antiproliferative and proapoptotic effects in addition to its potent antioxidant actions. Therefore, melatonin may be useful in the treatment of tumors in association with chemotherapy drugs. This study was performed to study the role of melatonin receptors on the cytotoxicity and apoptosis induced by the chemotherapeutic agents cisplatin and 5-fluorouracil in two tumor cell lines, such as human colorectal cancer HT-29 cells and cervical cancer HeLa cells. We found that both melatonin and the two chemotherapeutic agents tested induced a decrease in HT-29 and HeLa cell viability. Furthermore, melatonin significantly increased the cytotoxic effect of chemotherapeutic agents, particularly, in 5-fluorouracil-challenged cells. Stimulation of cells with either of the two chemotherapeutic agents in the presence of melatonin further increased caspase-3 activation. Concomitant treatments with melatonin and chemotherapeutic agents augmented the population of apoptotic cells compared to the treatments with chemotherapeutics alone. Blockade of MT1 and/or MT2 receptors with luzindole or 4-P-PDOT was unable to reverse the enhancing effects of melatonin on both cytotoxicity, caspase-3 activation and the amount of apoptotic cells evoked by the chemotherapeutic agents, whereas when MT3 receptors were blocked with prazosin, the synergistic effect of melatonin with chemotherapy on cytotoxicity and apoptosis was reversed. Our findings provided evidence that in vitro melatonin strongly enhances chemotherapeutic-induced cytotoxicity and apoptosis in two tumor cell lines, namely HT-29 and HeLa cells and, this potentiating effect of melatonin is mediated by MT3 receptor stimulation.

  15. Correlation between acceleration magnitude and ocular vestibular-evoked myogenic potential.

    Science.gov (United States)

    Wang, Shou-Jen; Jaw, Fu-Shan; Young, Yi-Ho

    2012-05-10

    This study combined bone-conducted vibration (BCV) stimulation with triaxial accelerometry to correlate the acceleration magnitudes of BCV stimuli with ocular vestibular-evoked myogenic potential (oVEMP) test results. Fourteen healthy volunteers underwent oVEMP test using BCV stimuli with simultaneous monitoring the triaxial acceleration. All (100%) subjects exhibited clear oVEMPs in response to BCV stimuli from a vibrator. The lowest acceleration magnitudes for eliciting oVEMPs along the x-, y- and z-axes were 0.05±0.01 g, 0.16±0.08 g, and 0.04±0.01 g, respectively, exhibiting significantly higher acceleration magnitude along the y-axis than those along the x- and z-axes. In addition, significantly positive correlations were noted between the acceleration magnitude along each axis and the oVEMP amplitude. In conclusion, measuring the acceleration magnitude throughout oVEMP testing revealed a significant correlation between linear acceleration and oVEMP responses. Restated, increasing acceleration magnitude may have more synchronization of firing of vestibular afferents, resulting in more synchronized evoked potentials and greater oVEMP amplitude. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  16. Corticobulbar motor evoked potentials from tongue muscles used as a control in cervical spinal surgery

    Directory of Open Access Journals (Sweden)

    Dong-Gun Kim

    Full Text Available Objective: Motor evoked potentials (MEPs changes might be caused to the non-surgically induced factors during cervical spinal surgery. Therefore, control MEPs recorded cranially to the exit of the C5 root are highly recommendable in cervical spinal surgery. We studied whether corticobulbar MEPs (C-MEPs from tongue muscle could be used as a control MEPs in cervical spinal surgery. Methods: Twenty-five consecutive cervical spinal surgeries were analyzed. Stimulation of motor area for tongue was done by subcutaneous electrodes placed at C3/C4 (10–20 EEG System, and recording was done from both sides of tongue. Results: C-MEPs were recorded successfully 24 out of the 25 (96% tested patients. Forty-six out of fifty MEPs (92% from tongue muscles were monitorable from the baseline. In two patients, we could obtain only unilateral C-MEPs. Mean MEPs latencies obtained from the left and right side of the tongue were 11.5 ± 1 ms and 11.5 ± 0.8 ms, respectively. Conclusions: Monitoring C-MEPs from tongue muscles might be useful control in cervical spinal surgery. They were easily elicited and relatively free from phenomenon of peripheral stimulation of the hypoglossal nerves. Significance: This is first study to identify the usefulness of C-MEPs as a control of cervical spinal surgery. Keywords: Intraoperative neurophysiological monitoring, Motor-evoked potential, Corticospinal tract, Corticobulbar MEPs, Hypoglossal nerve

  17. Can a finding of cervical vestibular evoked myogenic potentials contribute to vestibular migraine diagnostics?

    Directory of Open Access Journals (Sweden)

    Tihana Vešligaj

    2016-02-01

    Full Text Available Aim To investigate differences in vestibular evoked myogenic potentials (VEMP results with patients suffering from vestibular migraine and healthy people, taking into consideration values of threshold and latency of occurrence of the characteristic wave complex, size of amplitude, and interaural amplitude ratio. According to the results, determine the importance and usefulness of VEMP in vestibular migraine diagnostics. Methods A total number of 62 subjects were included in the study, 32 of them belonging to a group of patients suffering from vestibular migraine (VM, while other 30 were in a control group of healthy subjects. Information was collected during the diagnostic evaluation. General and otoneurological history of patients and bedside tests, audiological results, videonystagmography and cervical vestibular evoked myogenic potentials (cVEMP were made. Results There was a difference in an interaural ratio of amplitudes in the experimental and control groups, but it was not found to be clinically significant. By ToneBurst 500 Hz method, the interaural amplitude ratio higher than 35% was measured in 46.97% subjects, while the response was totally unilaterally missing in 28.8% patients. Conclusion Even the sophisticated method as cVEMP does not give the ultimate result confirming the vestibular migraine diagnosis, and neither do other diagnostic methods. cVEMP result can contribute to the completion of full mosaic of vestibular migraine diagnostics.

  18. [Recommendations for the clinical use of motor evoked potentials in multiple sclerosis].

    Science.gov (United States)

    Fernández, V; Valls-Sole, J; Relova, J L; Raguer, N; Miralles, F; Dinca, L; Taramundi, S; Costa-Frossard, L; Ferrandiz, M; Ramió-Torrentà, Ll; Villoslada, P; Saiz, A; Calles, C; Antigüedad, A; Alvarez-Cermeño, J C; Prieto, J M; Izquierdo, G; Montalbán, X; Fernández, O

    2013-09-01

    To establish clinical guidelines for the clinical use and interpretation of motor evoked potentials (MEP) in diagnosing and monitoring patients with multiple sclerosis (MS). Recommendations for MEP use and interpretation will help us rationalise and optimise resources used in MS patient diagnosis and follow up. We completed an extensive literature review and pooled our own data to produce a consensus statement with recommendations for the clinical use of MEPs in the study of MS. MEPs, in addition to spinal and cranial magnetic resonance imaging (MRI), help us diagnose and assess MS patients whose disease initially presents as spinal cord syndrome and those with non-specific brain MRI findings, or a normal brain MRI and clinical signs of MS. Whenever possible, a multimodal evoked potential study should be performed on patients with suspected MS in order to demonstrate involvement of the motor pathway which supports a diagnosis of dissemination in space. Copyright © 2012 Sociedad Española de Neurología. Published by Elsevier Espana. All rights reserved.

  19. Onset Latency of Motor Evoked Potentials in Motor Cortical Mapping with Neuronavigated Transcranial Magnetic Stimulation.

    Science.gov (United States)

    Kallioniemi, Elisa; Pitkänen, Minna; Säisänen, Laura; Julkunen, Petro

    2015-01-01

    Cortical motor mapping in pre-surgical applications can be performed using motor evoked potential (MEP) amplitudes evoked with neuronavigated transcranial magnetic stimulation. The MEP latency, which is a more stable parameter than the MEP amplitude, has not so far been utilized in motor mapping. The latency, however, may provide information about the stress in damaged motor pathways, e.g. compression by tumors, which cannot be observed from the MEP amplitudes. Thus, inclusion of this parameter could add valuable information to the presently used technique of MEP amplitude mapping. In this study, the functional cortical representations of first dorsal interosseous (FDI), abductor pollicis brevis (APB) and abductor digiti minimi (ADM) muscles were mapped in both hemispheres of ten healthy righthanded volunteers. The cortical muscle representations were evaluated by the area and centre of gravity (CoG) by using MEP amplitudes and latencies. As expected, the latency and amplitude CoGs were congruent and were located in the centre of the maps but in a few subjects, instead of a single centre, several loci with short latencies were observed. In conclusion, MEP latencies may be useful in distinguishing the cortical representation areas with the most direct pathways from those pathways with prolonged latencies. However, the potential of latency mapping to identify stressed motor tract connections at the subcortical level will need to be verified in future studies with patients.

  20. [Evoked potentials and regional cerebral blood flow changes in conversion disorder: a case report and review].

    Science.gov (United States)

    Gürses, Nadide; Temuçin, Cağri Mesut; Lay Ergün, Eser; Ertuğrul, Aygün; Ozer, Suzan; Demir, Başaran

    2008-01-01

    Conversion disorder is defined as the presence of functional impairment in motor, sensory or neurovegetative systems which cannot be explained by a general medical condition. Although the diagnostic systems emphasize the absence of an organic basis for the dysfunction in conversion disorder, there has been a growing interest in the specific functional brain correlates of conversion symptoms in recent years, particularly by examining neuroimaging and neurophysiological measures. In this case report, regional cerebral blood flow changes and evoked potentials of a patient with conversion symptoms are presented. Somatosensory evoked potentials (SEP) of this patient with conversion disorder who had signs of movement disorder revealed that the latency to N20, P 25 waves were in normal limits while the amplitudes of the P25 and N33 components were extremely high (giant SEP). Regional cerebral blood flow assessment revealed hypoperfusion in the left parietal and temporal lobes of the brain. Three months after the first assessment, the control scans showed that the left parietal hypoperfusion disappeared while the left temporal hypoperfusion was still present. The following SEP evaluations which were repeated twice in three months intervals after the initial recordings, showed the persistence of the abnormalities in somatosensorial measures. The neurophysiological and neuroimaging findings in conversion disorder were reviewed and the results of the evaluations of this case were discussed in this article.

  1. Somatosensory Evoked Potentials suppression due to remifentanil during spinal operations; a prospective clinical study

    Directory of Open Access Journals (Sweden)

    Christodoulou Anastasios

    2010-05-01

    Full Text Available Abstract Background Somatosensory evoked potentials (SSEP are being used for the investigation and monitoring of the integrity of neural pathways during surgical procedures. Intraoperative neurophysiologic monitoring is affected by the type of anesthetic agents. Remifentanil is supposed to produce minimal or no changes in SSEP amplitude and latency. This study aims to investigate whether high doses of remifentanil influence the SSEP during spinal surgery under total intravenous anesthesia. Methods Ten patients underwent spinal surgery. Anesthesia was induced with propofol (2 mg/Kg, fentanyl (2 mcg/Kg and a single dose of cis-atracurium (0.15 mg/Kg, followed by infusion of 0.8 mcg/kg/min of remifentanil and propofol (30-50 mcg/kg/min. The depth of anesthesia was monitored by Bispectral Index (BIS and an adequate level (40-50 of anesthesia was maintained. Somatosensory evoked potentials (SSEPs were recorded intraoperatively from the tibial nerve (P37 15 min before initiation of remifentanil infusion. Data were analysed over that period. Results Remifentanil induced prolongation of the tibial SSEP latency which however was not significant (p > 0.05. The suppression of the amplitude was significant (p Conclusion Remifentanil in high doses induces significant changes in SSEP components that should be taken under consideration during intraoperative neuromonitoring.

  2. Color vision in attention-deficit/hyperactivity disorder: a pilot visual evoked potential study.

    Science.gov (United States)

    Kim, Soyeon; Banaschewski, Tobias; Tannock, Rosemary

    2015-01-01

    Individuals with attention-deficit/hyperactivity disorder (ADHD) are reported to manifest visual problems (including ophthalmological and color perception, particularly for blue-yellow stimuli), but findings are inconsistent. Accordingly, this study investigated visual function and color perception in adolescents with ADHD using color Visual Evoked Potentials (cVEP), which provides an objective measure of color perception. Thirty-one adolescents (aged 13-18), 16 with a confirmed diagnosis of ADHD, and 15 healthy peers, matched for age, gender, and IQ participated in the study. All underwent an ophthalmological exam, as well as electrophysiological testing color Visual Evoked Potentials (cVEP), which measured the latency and amplitude of the neural P1 response to chromatic (blue-yellow, red-green) and achromatic stimuli. No intergroup differences were found in the ophthalmological exam. However, significantly larger P1 amplitude was found for blue and yellow stimuli, but not red/green or achromatic stimuli, in the ADHD group (particularly in the medicated group) compared to controls. Larger amplitude in the P1 component for blue-yellow in the ADHD group compared to controls may account for the lack of difference in color perception tasks. We speculate that the larger amplitude for blue-yellow stimuli in early sensory processing (P1) might reflect a compensatory strategy for underlying problems including compromised retinal input of s-cones due to hypo-dopaminergic tone. Copyright © 2014 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

  3. Effects of stimulation intensity, gender and handedness upon auditory evoked potentials

    Directory of Open Access Journals (Sweden)

    Susana Camposano

    1992-03-01

    Full Text Available Left handers and women show less anatomical brain asymmetry, larger corpus callosum and more bilateral representation of specific functions. Sensory and cognitive components of cortical auditory evoked potentials (AEF have been shown to be asymmetric in right handed males and to be influenced by stimulus intensity. In this study the influence of sex, handedness and stimulus intensity upon AEP components is investigated under basal conditions of passive attention. 14 right handed males, 14 right handed females, 14 left handed males, and 14 left handed females were studied while lying awake and paying passive attention to auditory stimulation (series of 100 binaural clicks, duration 1 msec, rate 1/sec, at four intensities. Cz, C3 and C4 referenced to linked mastoids and right EOG were recorded. Analysis time was 400 msec, average evoked potentials were based on 100 clicks. Stimulus intensity and gender affect early sensory components (P1N1 and N1P2 at central leads, asymmetry is influenced only by handedness, right handers showing larger P1N1 amplitudes over the right hemisphere.

  4. Visual evoked potentials with CRT and LCD monitors: when newer is not better.

    Science.gov (United States)

    Husain, Aatif M; Hayes, Susan; Young, Margaret; Shah, Dharmen

    2009-01-13

    The stimulus for pattern reversal visual evoked potentials (PRVEP) has traditionally been delivered by a cathode ray tube (CRT) monitor. Liquid crystal display (LCD) monitors have become more affordable and are being used instead of CRT monitors for many applications. We tested the hypothesis that LCD monitors were equivalent to CRT monitors when used for PRVEP. Monocular, full field PRVEP with a 32' check size were obtained in six normal subjects with a CRT monitor and LCD monitors having 2 msec, 8 msec, and 30 msec response times. The average P100 latency with the CRT screen was compared to the latencies with the LCD screens. The mean P100 latency of the CRT monitor was 107.7 (+/-6.6) ms, for the LCD 2 msec monitor was 115.7 (+/-6.9; p LCD 8 msec monitor was 118.5 (+/-6.5; p LCD 30 msec monitor was 156.8 (+/-6.8; p LCD) monitors do not provide data comparable to cathode ray tube (CRT) monitors. LCD monitors cannot replace CRT monitors for pattern reversal visual evoked potentials unless new normative data are obtained.

  5. An analysis of vestibular evoked myogenic potentials in patients with benign paroxysmal positional vertigo.

    Science.gov (United States)

    Yetiser, Sertac; Ince, Dilay; Gul, Murat

    2014-10-01

    Vestibular evoked myogenic potentials (VEMPs) selectively test the vestibular end-organ. The aim of this study was to analyze how the site of the diseased canal, type of particulate deposition, duration of symptoms, severity of nystagmus, recurrence, and age affect the VEMP in patients with benign paroxysmal positional vertigo (BPPV). One hundred two patients were enrolled in the study between 2009 and 2012. There were 36 men and 66 women with ages ranging from 16 to 71 years (mean age, 42.28 ± 11.29 years). Patients with BPPV were tested with roll-on and head-hanging maneuvers under video-electronystagmography monitoring and with air conduction cervical VEMP testing. Patients were grouped for duration, severity, recurrence, age, site of canal involvement, and so on, and the results were compared in each subgroup. Kruskal-Wallis and Mann-Whitney U tests were used for the comparative analysis. Twenty-four patients (23.5%) had a gross VEMP abnormality (absence of VEMP in 6 and greater than 25% depression of the amplitude in 18). Abnormality of VEMPs was not correlated with factors including age, severity of nystagmus, number of maneuvers applied, and the site of canal involvement (P < .05). However, persistence or recurrence of symptoms has an effect on VEMP results (P = .016). Vestibular evoked myogenic potential is a useful tool to study the otolithic function in patients with BPPV and should be included in the test battery. © The Author(s) 2014.

  6. Otolithic disease: clinical features and the role of vestibular evoked myogenic potentials.

    Science.gov (United States)

    Curthoys, Ian S; Manzari, Leonardo

    2013-07-01

    Through selective tests of the function of the canal and otolith sense organs, it is possible to assert that patient conditions are purely otolithic and that the canals are not involved. The video head impulse test selectively tests each semicircular canal; the ocular vestibular-evoked myogenic potential to 500 Hz Fz (Fz is the location on the forehead in the midline at the hairline) bone-conducted vibration (BCV) selectively tests the utricular macula and the cervical vestibular-evoked myogenic potential to 500 Hz Fz BCV selectively tests the saccular macula. The development of new specific tests of otolith function has shown that some patients may have specific deficits of just otolithic function. In the authors' experience, patients who complain strongly of postural unsteadiness should be suspected to have otolithic deficits. They may also have vertigo and in some cases have spontaneous nystagmus of peripheral origin, even though their semicircular canal function is normal. The prognosis for such patients is good. They usually appear to regain their postural stability spontaneously over weeks (or longer), even though they still have an otolithic deficit as shown by objective tests when they are free of symptoms. It is not known what procedures may accelerate the recovery of otolith function. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  7. Cervical and ocular vestibular evoked potentials in Machado-Joseph disease: Functional involvement of otolith pathways.

    Science.gov (United States)

    Ribeiro, Rodrigo Souza; Pereira, Melissa Marques; Pedroso, José Luiz; Braga-Neto, Pedro; Barsottini, Orlando Graziani Povoas; Manzano, Gilberto Mastrocola

    2015-11-15

    Machado-Joseph disease is defined as an autosomal dominant ataxic disorder caused by degeneration of the cerebellum and its connections and is associated with a broad range of clinical symptoms. The involvement of the vestibular system is responsible for several symptoms and signs observed in the individuals affected by the disease. We measured cervical and ocular vestibular evoked myogenic potentials in a sample of Machado-Joseph disease patients in order to assess functional pathways involved. Bilateral measures of cervical and ocular vestibular evoked myogenic potentials (cVEMP and oVEMP) were obtained from 14 symptomatic patients with genetically proven Machado-Joseph disease and compared with those from a control group of 20 healthy subjects. Thirteen (93%) patients showed at least one abnormal test result; oVEMP and cVEMP responses were absent in 17/28 (61%) and 11/28 (39%) measures, respectively; and prolonged latency of cVEMP was found in 3/28 (11%) measures. Of the 13 patients with abnormal responses, 9/13 (69%) patients showed discordant abnormal responses: four with absent oVEMP and present cVEMP, two with absent cVEMP and present oVEMP, and three showed unilateral prolonged cVEMP latencies. Both otolith-related vestibulocollic and vestibulo-ocular pathways are severely affected in Machado-Joseph disease patients evaluated by VEMPs. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Return of motor evoked potentials after knee flexion in the setting of high-grade spondylolisthesis.

    Science.gov (United States)

    Tilan, Justin; Andras, Lindsay M; Krieger, Mark D; Skaggs, David L

    2017-03-01

    To present a case of loss of motor-evoked potentials (MEPs) to the left foot in the supine position after a partial reduction and instrumented fusion from L4 to pelvis which was managed successfully without revision or removal of implants. We report a patient with high-grade spondylolisthesis who demonstrated loss of motor-evoked potentials after posterior spinal fusion and transfer to supine position. The patient's knees were flexed to 90° and signals were immediately restored. Systemic steroids were administered and circumferential fusion was delayed 21 days. Anterior-interbody cage was placed without complication. She was discharged on post-operative day 2. At 7 months, she is pain free and doing well with plans to return to gymnastics completely. Knee flexion can be instituted when encountering a neuromonitoring signal change following posterior spinal fusion for spondylolisthesis as a means to alleviate acute nerve stretch injury and may in some cases prevent the need to lessen the correction. IV.

  9. Influence of blood pressure manometer feedback on the parameters of the vestibular evoked myogenic potential test.

    Science.gov (United States)

    Suh, Myung-Whan; Kim, Ji Soo; Koo, Ja-Won

    2009-04-01

    The objective of this study was to evaluate the merits of a blood pressure (BP) manometry feedback method for measurement of vestibular evoked myogenic potentials. Sixty ears of 30 normal volunteers were prospectively investigated. The vestibular evoked myogenic potentials were recorded under 3 different conditions: in the feedback-negative (FB-) condition, ie, in a sitting position without feedback; in the feedback-positive (FB+) condition, ie, in a sitting position with self-monitored BP feedback (using a BP cuff); and in a supine condition, ie, in a supine position without feedback. The interaural amplitude difference (IAD) ratios and interaural latency differences were analyzed. The mean IAD ratio was smaller in the FB+ condition than in the FB- and supine conditions, but the difference was without statistical significance. The upper limits of the normal range of the IAD ratios were 39.5%, 18.3%, and 25.9% for the FB-, FB+, and supine conditions, respectively. The interaural latency difference of p13 was significantly smaller in the supine condition than in the FB- and FB+ conditions. Although the reduction of the mean IAD ratio did not reach statistical significance by feedback monitoring in our study, feedback using a BP manometer may have some clinical significance, in that a more stable IAD ratio may be obtained with a narrower normal range and a smaller variation.

  10. Electromagnetic characterization of living action potential

    OpenAIRE

    Requena Pozo, Borja

    2017-01-01

    Brain imaging is a vanguard and promising topic with uncountable applications in several fields. This project is driven by the development of a new brain imaging technique that could provide activity information with spatial resolution using microwaves. Being cognition based on the action potential phenomenon, in order to see whether its effects on the dielectric properties of the medium are visible, a plant capable of propagating action potentials is used as experimental subject, constitutin...

  11. Comparison of the pattern reversal visual evoked potential mediated by separate cone systems

    DEFF Research Database (Denmark)

    Johnsen, B; Frederiksen, J.L.; Larsson, H.B.

    1995-01-01

    With the purpose of recording responses mediated by the 3 cone systems visual evoked potentials (VEPs) were elicited by the reversal of monochromatic checkerboards superimposed upon strong monochromatic backgrounds (yellow, purple and blue-green). The sensitivity to light of various wave lengths...... were measured as the reciprocal of the intensity necessary to elicit a VEP amplitude of 3 microV. The spectral sensitivity curves based on this VEP amplitude criterion in the presence of blue-green, purple and yellow adaptation showed peak sensitivities in the red, the green and the blue part...... of the spectrum, respectively. This indicates that the responses reflect separate modulation of the 3 different cone mechanisms. The potentials obtained with yellow adaptation differed from those obtained with purple and blue-green adaptation. The amplitude versus log intensity function was flatter...

  12. A portable, differential amplifier for recording high frequency EEG signals and evoked potentials

    International Nuclear Information System (INIS)

    Donos, Cristian; Giurgiu, Liviu; Popescu, Aurel; Mocanu, Marian

    2010-01-01

    In a clinical context, EEG refers to recording the brain's spontaneous electric activity, using small electrodes placed on the scalp. The signals collected are electric 'potentials' measured between two electrodes. Usually, for a healthy adult, these signals have small voltage (10 μV to 100 μV) and frequencies in the 0-40 Hz range. In the scientific literature, there are mentioned EEG signals and evoked potentials that have higher frequencies (up to 600 Hz) and amplitudes lower than 500 ηV. For this reason, building an amplifier capable of recording EEG signals in the ηV range and with frequencies up to couple of kHz is necessary to continue research beyond 600 Hz. We designed a very low noise amplifier that is able to measure/record EEG signals in the ηV range over a very large frequency bandwidth (0.09 Hz -385 kHz).(Author)

  13. Epidural motor cortex stimulation suppresses somatosensory evoked potentials in the primary somatosensory cortex of the rat.

    Science.gov (United States)

    Chiou, Ruei-Jen; Lee, Hsiao-Yun; Chang, Chen-Wei; Lin, Kuan-Hung; Kuo, Chung-Chih

    2012-06-29

    Motor cortex stimulation (MCS) is a promising clinical procedure to help alleviate chronic pain. Animal models demonstrated that MCS is effective in lessening nocifensive behaviors. The present study explored the effects of MCS on cortical somatosensory evoked potentials (SEPs) recorded at the primary somatosensory cortex (SI) of the rat. SEPs were evoked by electrical stimulation applied to the contralateral forepaws. Effects of different intensities, frequencies, and durations of MCS were tested. MCS at ≥2V suppressed SEPs of the ipsilateral SI. Suppression lasted 120 min at an intensity of 5 V. The optimal frequency was 50 Hz, and the duration was 30s. In contrast, MCS did not affect SEPs recorded on the contralateral SI. Cortical stimulation out of the motor cortex did not induce a decrease in the ipsilateral SEPs. We also investigated involvement of the endogenous opioid system in this inhibition of SEPs induced by MCS. The opioid antagonist, naloxone (0.5 mg/kg), was administered 30 min before MCS. Application of naloxone completely prevented the inhibitory effect of MCS on ipsilateral SEPs. These results demonstrate that MCS blocked the transmission of somatosensory information to the primary somatosensory cortex, and this interference was mediated by the endogenous opioid system. This inhibitory effect on sensory transmission induced by MCS may reflect its antinociceptive effect. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Functional mapping of the sensorimotor cortex: combined use of magnetoencephalography, functional MRI, and motor evoked potentials

    Energy Technology Data Exchange (ETDEWEB)

    Morioka, T. [Dept. of Neurosurgery, Neurological Inst., Kyshu Univ., Fukuoka (Japan); Fujii, K. [Dept. of Neurosurgery, Neurological Inst., Kyshu Univ., Fukuoka (Japan); Fukui, M. [Dept. of Neurosurgery, Neurological Inst., Kyshu Univ., Fukuoka (Japan); Mizushima, A. [Dept. of Radiology, Kyushu Univ. Fukuoka (Japan); Matsumoto, S. [Dept. of Radiology, Kyushu Univ. Fukuoka (Japan); Hasuo, K. [Dept. of Radiology, Kyushu Univ. Fukuoka (Japan); Yamamoto, T. [Dept. of Otolaryngology, Kyushu Univ. Fukuoka (Japan); Tobimatsu, S. [Dept. of Clinical Neurophysiology, Neurological Inst., Kyushu Univ., Fukuoka (Japan)

    1995-10-01

    Combined use of magnetoencephalography (MEG), functional magnetic resonance imaging (f-MRI), and motor evoked potentials (MEPs) was carried out on one patient in an attempt to localise precisely a structural lesion to the central sulcus. A small cyst in the right frontoparietal region was thought to be the cause of generalised seizures in an otherwise asymptomatic woman. First the primary sensory cortex was identified with magnetic source imaging (MSI) of somatosensory evoked magnetic fields using MEG and MRI. Second, the motor area of the hand was identified using f-MRI during handsqueezing. Then transcranial magnetic stimulation localised the hand motor area on the scalp, which was mapped onto the MRI. There was a good agreement between MSI, f-MRI and MEP as to the location of the sensorimotor cortex and its relationship to the lesion. Multimodality mapping techniques may thus prove useful in the precise localisation of cortical lesions, and in the preoperative determination of the best treatment for peri-rolandic lesions. (orig.)

  15. Functional mapping of the sensorimotor cortex: combined use of magnetoencephalography, functional MRI, and motor evoked potentials

    International Nuclear Information System (INIS)

    Morioka, T.; Fujii, K.; Fukui, M.; Mizushima, A.; Matsumoto, S.; Hasuo, K.; Yamamoto, T.; Tobimatsu, S.

    1995-01-01

    Combined use of magnetoencephalography (MEG), functional magnetic resonance imaging (f-MRI), and motor evoked potentials (MEPs) was carried out on one patient in an attempt to localise precisely a structural lesion to the central sulcus. A small cyst in the right frontoparietal region was thought to be the cause of generalised seizures in an otherwise asymptomatic woman. First the primary sensory cortex was identified with magnetic source imaging (MSI) of somatosensory evoked magnetic fields using MEG and MRI. Second, the motor area of the hand was identified using f-MRI during handsqueezing. Then transcranial magnetic stimulation localised the hand motor area on the scalp, which was mapped onto the MRI. There was a good agreement between MSI, f-MRI and MEP as to the location of the sensorimotor cortex and its relationship to the lesion. Multimodality mapping techniques may thus prove useful in the precise localisation of cortical lesions, and in the preoperative determination of the best treatment for peri-rolandic lesions. (orig.)

  16. Clinical application of multifocal visual evoked potentials in children with epilepsy caused by intracranial disease

    International Nuclear Information System (INIS)

    Yukawa, Eiichi; Kim, Yeong-Jin; Kawasaki, Kensuke; Yoshii, Toshiaki; Hara, Yoshiaki

    2006-01-01

    We investigated whether visual field defects could be objectively evaluated using multifocal visual evoked potential (m-VEP) in two children with epilepsy caused by intracranial disease in whom it was difficult to measure the visual field. To determine normal waves in m-VEP, recording was performed using a visual evoked response imaging system (VERIS) Junior Science program (Mayo, Aichi, Japan) in 20 healthy children (20 eyes) peak latency and amplitude were used for assessment. In the two children with epilepsy, m-VEPs were recorded, and compared with the results of static perimetry or the lesions observed by Magnetic Resonance Imaging (MRI). In the 20 healthy children, there was no significant difference in the peak latency or amplitude among 4 quadrants by one-way analysis of variance. m-VEP in the children with epilepsy showed abnormal waves, corresponding to the visual field defects in the static perimetry or the lesions observed by MRI. Objective evaluation of visual field defects using m-VEP may be useful in children with epilepsy caused by intracranial disease in whom kinetic/static perimetry as a subjective examination is difficult. (author)

  17. A psycho-verbal stimulation interface for the cognitive evoked potentials acquisition.

    Science.gov (United States)

    Dionisie, B; Costin, H; Luca, Veronica

    2008-01-01

    The psycho-verbal stimulation interface, created by us, represents an IT extension of an EEG / EMG device dedicated for the human brain Evoked Potentials acquisitions (EPs). The psycho-verbal stimulation interface was created as a .NET application and was written in the C# language with respect to the OOP paradigm. It uses the TL logic to command the EPs acquisition module. The signal is send on the parallel port (LPT1) to the EPs device by a dedicated hardware interface. The software module was designed as a multi-threading application in order to perform more than one operation once. The stimulus sample can be customized as text, image or both and each stimulus sequence follows also a fully configurable time schema. The application can measure the patient's reaction time to each stimulus sample, which are finally centralized on a list control. The system can save both the test sequences and the EEG diagrams in digital formats; the resulted files can be stored and delivered online using the Telemes web application. The Telmes project implemented a secured & scalable tele-medical centers network dedicated to the telemonitoring & tele-consulting services, and the psycho-verbal stimulation interface is one of the instruments devoted to these goals. The psycho-verbal stimulation interface can be used as a medical research tool for study the cognitive processes of reading, memory or learning using the endogenous visual event related potentials, as good as a instrument of training the recovery of sensitive language, which can be delivered at home by the neuro-linguist specialist as daily lists programs. The visual evoked potentials and the reaction times collected from the patients can facilitate a prognostic diagnosis of recovery the language.

  18. Obstacles in using a computer screen for steady-state visually evoked potential stimulation.

    Science.gov (United States)

    Olze, Katharina; Jan Wehrmann, Christof; Mu, Luyang; Schilling, Meinhard

    2017-11-28

    In brain computer interface (BCI) applications, the use of steady-state visually evoked potentials (SSVEPs) is common. Therefore, a visual stimulation with a constant repetition frequency is necessary. However, using a computer monitor, the set of frequencies that can be used is restricted by the refresh rate of the screen. Frequencies that are not an integer divisor of the refresh rate cannot be displayed correctly. Furthermore, the programming language the stimulation software is written in and the operating system influence the actually generated and presented frequencies. The aim of this paper is to identify the main challenges in generating SSVEP stimulation using a computer screen with and without using DirectX in Windows-based PC systems and to provide solutions for these issues.

  19. Modulation of sensory inhibition of motor evoked potentials elicited by TMS prior to movement?

    DEFF Research Database (Denmark)

    Leukel, Christian; Lundbye-Jensen, Jesper; Nielsen, Jens Bo

    Short latency afferent inhibition (SAI) refers to a decrement of the size of a motor evoked potential (MEP) by transcranial magnetic stimulation (TMS) after electrical stimulation of a peripheral afferent nerve (PNS) (Tokimura et al. 2000). Since SAI occurs when TMS is applied at the time...... of the arrival of the peripheral afferent volley at the sensorimotor cortex, it likely reflects sensory activation of inhibitory intracortical circuits (Alle et al. 2009). In the present study, we aimed to investigate modulation of this inhibitory effect prior to movement (flexion of the index finger) compared...... of corticospinal cells to TMS, which starts approximately 100 ms prior to the onset of movement (Chen et al. 1998). Thus, it is hypothesized that the modulation of the MEP prior to movement is linked to the afferent volley arriving at the sensorimotor cortex. It might be speculated that the MEP was facilitated...

  20. Effect of epidural 0.25% bupivacaine on somatosensory evoked potentials to dermatomal stimulation

    DEFF Research Database (Denmark)

    Lund, C; Hansen, O B; Kehlet, H

    1989-01-01

    The effect of lumbar epidural analgesia with similar volumes (about 25 ml) of 0.25% and 0.5% bupivacaine on early (less than 0.5 seconds) somatosensory evoked potentials (SEPs) to electrical stimulation of the S1, L1, and T10 dermatomes was examined in two groups of ten patients. Level of sensory...... analgesia to pinprick was T5.7 +/- 0.8 and T6.4 +/- 0.7 in the 0.25% and 0.5% bupivacaine group, respectively. Motor blockade was more pronounced in the 0.5% bupivacaine group (p less than 0.05). Despite similar analgesia to pinprick, SEPs were more reduced during 0.5% bupivacaine than during 0...

  1. Visual evoked potentials show strong positive association with intracranial pressure in patients with cryptococcal meningitis

    Directory of Open Access Journals (Sweden)

    Marcelo Adriano da Cunha Silva Vieira

    2015-04-01

    Full Text Available Objective : To verify the relationship between intracranial pressure and flash visual evoked potentials (F-VEP in patients with cryptococcal meningitis. Method The sample included adults diagnosed with cryptococcal meningitis admitted at a reference hospital for infectious diseases. The patients were subjected to F-VEP tests shortly before lumbar puncture. The Pearson’s linear correlation coefficient was calculated and the linear regression analysis was performed. Results : Eighteen individuals were subjected to a total of 69 lumbar punctures preceded by F-VEP tests. At the first lumbar puncture performed in each patient, N2 latency exhibited a strong positive correlation with intracranial pressure (r = 0.83; CI = 0.60 - 0.94; p < 0.0001. The direction of this relationship was maintained in subsequent punctures. Conclusion : The intracranial pressure measured by spinal tap manometry showed strong positive association with the N2 latency F-VEP in patients with cryptococcal meningitis.

  2. Magnetic resonance imaging compared with trimodal evoked potentials in possible multiple sclerosis

    International Nuclear Information System (INIS)

    Roullet, E.; Leger-Ravet, M.B.; Amarenco, P.; Marteau, R.; Lavallard-Rousseau, M.-C.; Dupuch, K.; Iba-Zizen, M.T.; Tamraz, J.; Cabanis, E.A.

    1988-01-01

    Magnetic Resonance Imaging (MRI) of the brain and Evoked Potentials (EP) can both demonstrate the presence of clinically unsuspected demyelinating lesions and have proven to be sensitive (but not specific) in the diagnosis of multiple sclerosis (MS). MRI and EP are positive in 90 to 100% of patients with a definite diagnosis of MS. However, few studies have been conducted in patients with a lesser diagnostic certainty. In possible or suspected MS they gave conflicting results, possibly because of technical discrepancies and different clinical inclusion criteria. Since a number of putative new treatments can be evaluated in patients who have a definite diagnosis of MS, but nevertheless a short duration of disease and a low disability, it was decided to compare the sensitivity of MRI and EP as diagnostic tools in possible MS patients. MRI is shown to be more sensitive, shows more multiple lesions and gives a clearer appreciation of their size and exact location than EP. 10 refs.; 3 tabs

  3. Early impairment of somatosensory evoked potentials in very young children with achondroplasia with foramen magnum stenosis.

    Science.gov (United States)

    Fornarino, Stefania; Rossi, Daniela Paola; Severino, Mariasavina; Pistorio, Angela; Allegri, Anna Elsa Maria; Martelli, Simona; Doria Lamba, Laura; Lanteri, Paola

    2017-02-01

    To evaluate the contribution of somatosensory evoked potentials after median nerve (MN-SEPs) and posterior tibial nerve (PTN-SEPs) stimulation in functional assessment of cervical and lumbar spinal stenosis in children with achondroplasia. We reviewed MN-SEPs, PTN-SEPs, and spinal magnetic resonance imaging (MRI) examinations performed in 58 patients with achondroplasia (25 males, 33 females; age range 21d-16y 10mo; mean age 4y 3mo [SD 4y 1mo]). Patients were subdivided into four age categories: achondroplasia, the cortical component of PTN-SEPs is more sensitive than the cortical component and central conduction time of MN-SEPs in detection of cervical spinal cord compression at early ages. © 2016 Mac Keith Press.

  4. Augmented ocular vestibular evoked myogenic potentials to air-conducted sound in large vestibular aqueduct syndrome.

    Science.gov (United States)

    Taylor, Rachael L; Bradshaw, Andrew P; Magnussen, John S; Gibson, William P R; Halmagyi, G Michael; Welgampola, Miriam S

    2012-01-01

    To demonstrate the value of recording air-conducted ocular Vestibular Evoked Myogenic Potentials (oVEMP) in a patient with bilaterally enlarged vestibular aqueducts. Cervical VEMP and oVEMP were recorded from a patient presenting with bilateral hearing loss and imbalance, attributable to large vestibular aqueduct syndrome. The stimuli were air-conducted tone bursts at octave frequencies from 250 to 2000 Hz. Amplitudes and thresholds were measured and compared with the normal response range of 32 healthy control subjects. oVEMP reflexes demonstrated pathologically increased amplitudes and reduced thresholds for low-frequency tone bursts. Cervical VEMP amplitudes and thresholds were within normal limits for both ears across all frequencies of stimulation. This study is the first to describe the augmentation of AC oVEMPs in an adult with large vestibular aqueduct syndrome.

  5. [Anesthetic agents and visual evoked potentials in patients undergoing transphenoidal or breast reconstruction surgery].

    Science.gov (United States)

    Damiani Cavero, S; Viera Alemán, C; Santos Anzorandia, C; Bacallao Gallestey, J; Febles Piñar, E; Rivero Moreno, M

    1997-02-01

    To study the effect of general anesthesia with diazepam, fentanyl and nitric oxide, a common combination during the intraoperative recording of visual evoked potentials (VEP) in transsphenoidal surgery, we compared the amplitude and latency of VEP components before anesthesia and at four moments after induction during the first hour of elective breast surgery in 20 patients with no neurological deficits. The results for these patients (group I) before anesthesia and 15 min after induction were also compared to presurgical recordings for 19 patients with hypophysial tumors and histories visual field and acuity involvement (group II). Latency increased significantly as a result of anesthesia whereas amplitude was affected to a lesser degree. Changes in latency of the main positive component was after anesthesia was the only parameter that was significantly different for the two group studied, variation being greater in group II.

  6. Postoperative changes in visual evoked potentials and cognitive function tests following sevoflurane anaesthesia.

    LENUS (Irish Health Repository)

    Iohom, G

    2012-02-03

    We tested the hypothesis that minor disturbance of the visual pathway persists following general anaesthesia even when clinical discharge criteria are met. To test this, we measured visual evoked potentials (VEPs) in 13 ASA I or II patients who did not receive any pre-anaesthetic medication and underwent sevoflurane anaesthesia. VEPs were recorded on four occasions, before anaesthesia and at 30, 60, and 90 min after emergence from anaesthesia. Patients completed visual analogue scales (VAS) for sedation and anxiety, a Trieger Dot Test (TDT) and a Digit Symbol Substitution Test (DSST) immediately before each VEP recording. These results were compared using Student\\'s t-test. P<0.05 was considered significant. VEP latency was prolonged (P<0.001) and amplitude diminished (P<0.05) at 30, 60, and 90 min after emergence from anaesthesia, when VAS scores for sedation and anxiety, TDT, and DSST had returned to pre-anaesthetic levels.

  7. Does athletic training in volleyball modulate the components of visual evoked potentials? A preliminary investigation.

    Science.gov (United States)

    Zwierko, Teresa; Lubiński, Wojciech; Lesiakowski, Piotr; Steciuk, Hanna; Piasecki, Leszek; Krzepota, Justyna

    2014-01-01

    This longitudinal study investigated visual evoked potentials (VEPs) in 11 young female volleyball players who participated in extensive training for 2 years. The control group consisted of 7 age-matched female students who were not involved in any regular sports activity. Recordings of VEPs were performed twice: baseline recording (i.e., before training began) and after 2 years of systematic, volleyball-specific athletic training. The effect of athletic training on visual signal conductivity was assessed by recording the latency of N75, P100 and N135 components of the VEPs waveform. Extensive experience with volleyball training reduced signal conductivity time through visual pathway. Specifically, the latency of P100 was reduced on average by 2.2 ms during binocular viewing. Moreover, athletes had reduced N75 latency (difference of 3.3 ms) for visual stimuli that generated greater response from peripheral retina. These results indicate that sport training can affect very early sensory processing in athletes.

  8. Effect of nitric oxide on spinal evoked potentials and survival rate in rats with decompression sickness

    DEFF Research Database (Denmark)

    Randsøe, Thomas; Meehan, Claire Francesca; Broholm, Helle

    2015-01-01

    Nitric oxide (NO) releasing agents have, in experimental settings, been shown to decrease intravascular nitrogen bubble formation and to increase the survival rate during decompression sickness (DCS) from diving. The effect has been ascribed to a possible removal of preexisting micronuclei...... evaluated by means of spinal evoked potentials (SEPs). Anesthetized rats were decompressed from a 1-h hyperbaric air dive at 506.6 kPa (40 m of seawater) for 3 min and 17 s, and spinal cord conduction was studied by measurements of SEPs. Histological samples of the spinal cord were analyzed for lesions...... GTN (group 6) during the dive, before decompression. In all groups, decompression caused considerable intravascular bubble formation. The ISMN groups showed no difference compared with the control group, whereas the GTN groups showed a tendency toward faster SEP disappearance and shorter survival...

  9. Multifocal visual evoked potentials for quantifying optic nerve dysfunction in patients with optic disc drusen

    DEFF Research Database (Denmark)

    Malmqvist, Lasse; de Santiago, Luis; Boquete, Luciano

    2017-01-01

    and 22 control subjects were examined. Mean amplitude, mean inner ring (IR) amplitude (0.87-5.67° of visual field) and mean outer ring amplitude (5.68-24° of visual field) were calculated using signal-to-noise ratio (SNR) and peak-to-peak analysis. Monocular latency was calculated using second peak......PURPOSE: To explore the applicability of multifocal visual evoked potentials (mfVEPs) for research and clinical diagnosis in patients with optic disc drusen (ODD). This is the first assessment of mfVEP amplitude in patients with ODD. METHODS: MfVEP amplitude and latency from 33 patients with ODD......, full eye and IR. In the control group, SNR intersubject variability was 17.6% and second peak latency intersubject variability was 2.8%. CONCLUSION: Decreased mfVEP amplitude in patients with ODD suggests a direct mechanical compression of the optic nerve axons. Our results suggest that mfVEP amplitude...

  10. Low luminance/eyes closed and monochromatic stimulations reduce variability of flash visual evoked potential latency

    Directory of Open Access Journals (Sweden)

    Senthil Kumar Subramanian

    2013-01-01

    Full Text Available Context: Visual evoked potentials are useful in investigating the physiology and pathophysiology of the human visual system. Flash visual evoked potential (FVEP, though technically easier, has less clinical utility because it shows great variations in both latency and amplitude for normal subjects. Aim: To study the effect of eye closure, low luminance, and monochromatic stimulation on the variability of FVEPs. Subjects and Methods: Subjects in self-reported good health in the age group of 18-30 years were divided into three groups. All participants underwent FVEP recording with eyes open and with white light at 0.6 J luminance (standard technique. Next recording was done in group 1 with closed eyes, group 2 with 1.2 and 20 J luminance, and group 3 with red and blue lights, while keeping all the other parameters constant. Two trials were given for each eye, for each technique. The same procedure was repeated at the same clock time on the following day. Statistical Analysis: Variation in FVEP latencies between the individuals (interindividual variability and the variations within the same individual for four trials (intraindividual variability were assessed using coefficient of variance (COV. The technique with lower COV was considered the better method. Results: Recording done with closed eyes, 0.6 J luminance, and monochromatic light (blue > red showed lower interindividual and intraindividual variability in P2 and N2 as compared to standard techniques. Conclusions: Low luminance flash stimulations and monochromatic light will reduce FVEP latency variability and may be clinically useful modifications of FVEP recording technique.

  11. Visual evoked potentials in overt hypothyroid patients before and after achievement of euthyroidism

    Directory of Open Access Journals (Sweden)

    Aprajita

    2017-01-01

    Full Text Available Background: Visual evoked potential (VEP measures the time taken for visual stimulus to travel from the eye to the occipital cortex. Hypothyroidism affects the central nervous system (CNS through its role in gene expression, myelin production, axonal transportation, and neurotransmitters. Delay in the conduction of impulses results in abnormal VEP. Objective: Correlate the electrophysiological findings of VEP in newly diagnosed treatment-naive hypothyroid patients before and after 3 months of treatment and to find the correlation with serum thyroid-stimulating hormone (TSH levels. Materials and Methods: VEP was measured using Recorders and Medicare Systems Electromyograph Evoked Potential Mark II machine in 30 patients (serum TSH ≥10 mIU/L between 18 and 50 years of age who were followed up after 3 months of treatment. Results: The mean age (±standard deviation of the patients was 31.8 (±8.3 years. There was prolongation of VEP latencies which tends to decrease following hormone replacement therapy. It was found to be most significant for P100 (ms waveform (P < 0.001. The amplitude (P100-N75 mV which was decreased in hypothyroid patients showed improvement following achievement of euthyroidism. Significant positive correlation was found between P100, N75 latency and pretreatment serum TSH levels. Conclusion: Hypothyroid patients may have changes in the latencies and the amplitude of VEP which are reversible to a great extent with thyroxine replacement therapy. VEP thus acts as a dependable marker for CNS affection in thyroid diseases to detect subtle early changes and to assess the response to treatment in correlation with the clinical improvement.

  12. Brownian Optogenetic-Noise-Photostimulation on the Brain Amplifies Somatosensory-Evoked Field Potentials

    Directory of Open Access Journals (Sweden)

    Nayeli Huidobro

    2017-08-01

    Full Text Available Stochastic resonance (SR is an inherent and counter-intuitive mechanism of signal-to-noise ratio (SNR facilitation in biological systems associated with the application of an intermediate level of noise. As a first step to investigate in detail this phenomenon in the somatosensory system, here we examined whether the direct application of noisy light on pyramidal neurons from the mouse-barrel cortex expressing a light-gated channel channelrhodopsin-2 (ChR2 can produce facilitation in somatosensory evoked field potentials. Using anesthetized Thy1-ChR2-YFP transgenic mice, and a new neural technology, that we called Brownian optogenetic-noise-photostimulation (BONP, we provide evidence for how BONP directly applied on the barrel cortex modulates the SNR in the amplitude of whisker-evoked field potentials (whisker-EFP. In all transgenic mice, we found that the SNR in the amplitude of whisker-EFP (at 30% of the maximal whisker-EFP exhibited an inverted U-like shape as a function of the BONP level. As a control, we also applied the same experimental paradigm, but in wild-type mice, as expected, we did not find any facilitation effects. Our results show that the application of an intermediate intensity of BONP on the barrel cortex of ChR2 transgenic mice amplifies the SNR of somatosensory whisker-EFPs. This result may be relevant to explain the improvements found in sensory detection in humans produced by the application of transcranial-random-noise-stimulation (tRNS on the scalp.

  13. The influence of caffeine on calorics and cervical vestibular evoked myogenic potentials (cVEMPs).

    Science.gov (United States)

    McNerney, Kathleen; Coad, Mary Lou; Burkard, Robert

    2014-03-01

    Prior to undergoing vestibular function testing, it is not uncommon for clinicians to request that patients abstain from caffeine 24 hr prior to the administration of the tests. However, there is little evidence that caffeine affects vestibular function. To evaluate whether the results from two tests commonly used in a clinical setting to assess vestibular function (i.e., calorics and the cervical vestibular evoked myogenic potential [cVEMP]) are affected by caffeine. Subjects were tested with and without consuming a moderate amount of caffeine prior to undergoing calorics and cVEMPs. Thirty young healthy controls (mean = 23.28 yr; females = 21). Subjects were excluded if they reported any history of vestibular/balance impairment. The Variotherm Plus Caloric Irrigator was used to administer the water, while the I-Portal VNG software was used to collect and analyze subjects' eye movements. The TECA Evoked Potential System was used for the cVEMP stimulus presentation as well as for the data collection. During cVEMP collection, subjects were asked to monitor their sternocleidomastoid muscle contraction with a Delsys EMG monitor. IBM SPSS Statistics 20 was used to statistically analyze the results via paired t-tests. Analysis of the data revealed that ingestion of caffeine did not significantly influence the results of either test of vestibular function. The results revealed that a moderate amount of caffeine does not have a clinically significant effect on the results from caloric and cVEMP tests in young healthy adults. Future research is necessary to determine whether similar results would be obtained from individuals with a vestibular impairment, as well as older adults. American Academy of Audiology.

  14. Broad-Band Visually Evoked Potentials: Re(convolution in Brain-Computer Interfacing.

    Directory of Open Access Journals (Sweden)

    Jordy Thielen

    Full Text Available Brain-Computer Interfaces (BCIs allow users to control devices and communicate by using brain activity only. BCIs based on broad-band visual stimulation can outperform BCIs using other stimulation paradigms. Visual stimulation with pseudo-random bit-sequences evokes specific Broad-Band Visually Evoked Potentials (BBVEPs that can be reliably used in BCI for high-speed communication in speller applications. In this study, we report a novel paradigm for a BBVEP-based BCI that utilizes a generative framework to predict responses to broad-band stimulation sequences. In this study we designed a BBVEP-based BCI using modulated Gold codes to mark cells in a visual speller BCI. We defined a linear generative model that decomposes full responses into overlapping single-flash responses. These single-flash responses are used to predict responses to novel stimulation sequences, which in turn serve as templates for classification. The linear generative model explains on average 50% and up to 66% of the variance of responses to both seen and unseen sequences. In an online experiment, 12 participants tested a 6 × 6 matrix speller BCI. On average, an online accuracy of 86% was reached with trial lengths of 3.21 seconds. This corresponds to an Information Transfer Rate of 48 bits per minute (approximately 9 symbols per minute. This study indicates the potential to model and predict responses to broad-band stimulation. These predicted responses are proven to be well-suited as templates for a BBVEP-based BCI, thereby enabling communication and control by brain activity only.

  15. The motor evoked potential in AIDS and HAM/TSP: state of the evidence.

    Science.gov (United States)

    Leon-Sarmiento, Fidias E; Elfakhani, Mohamed; Boutros, Nash N

    2009-12-01

    We aimed to better understand the involvement of the corticospinal tract, assessed by non-invasive transcranial stimulation, in order to determine the actual involvement of the motor system in patients with HAM/TSP and AIDS. An exhaustive MEDLINE search for the period of 1985 to 2008 for all articles cross-referenced for 'HTLV-I, HTLV-II, HTLV-III and HIV, HIV1, HIV2, evoked potential, motor evoked potential, high voltage electrical stimulation, transcranial magnetic stimulation, magnetic stimulation, corticomotor physiology, motor pathways, acquired immunodeficiency syndrome, AIDS, SIDA, tropical spastic paraparesis, HTLV-I-associated myelopathy, HAM, TSP, and HAM/TSP' were selected and analysed. Eighteen papers published in English, Spanish, Portuguese, French and Japanese were identified. Only the central motor conduction time has been analyzed in seropositive patients to human retroviruses. The investigations done on HAM/TSP support the involvement of the pyramidal tract mainly at lower levels, following a centripetal pattern; in AIDS, such an involvement seems to be more prominent at brain levels following a centrifugal pattern. The central motor conduction time abnormalities and involvement differences of the corticospinal tract of patients with AIDS and HAM/TSP dissected here would allow to re-orient early neurorehabilitation measures in these retroviruses-associated neurodegenerative disorders. Besides this, more sophisticated and sensitive non-invasive corticospinal stimulation measures that detect early changes in thalamocortical-basal ganglia circuitry will be needed in both clinically established as well as asymptomatic patients at times when the fastest corticospinal fibers remain uninvolved.

  16. Multimodal evoked potentials in spinocerebellar ataxia types 1, 2, and 3

    Directory of Open Access Journals (Sweden)

    Vijay Chandran

    2014-01-01

    Full Text Available Aims: Spinocerebellar ataxias (SCA are a clinically heterogeneous group of disorders that are characterized by ataxia and an autosomal dominant pattern of inheritance. The aim of our study was to describe the findings of evoked potentials (EPs among genetically proven SCA types 1, 2, and 3 and to additionally evaluate if EPs can be used to differentiate between them. Materials and Methods: Forty-three cases of genetically proven SCA (SCA1 = 19, SCA2 = 13, and SCA3 = 11 were evaluated with median somatosensory-EP (mSSEP, visual-EP (VEP, and brainstem auditory-evoked response (BAER by standard procedures and compared with normative laboratory data. An EP was considered abnormal if latency was prolonged (>mean + 3 standard deviation (SD of laboratory control data or the waveform was absent or poorly defined. The waves studied were as follows: mSSEP - N20, VEP - P100 and BAER - interpeak latency 1-3 and 3-5. Results: EPs were abnormal in at least one modality in 90.9% of patients. The most common abnormality was of BAER (86.1% followed by VEP (34.9% and mSSEP (30.2%. The degree of abnormality in VEP, mSSEP, and BAER among patients with SCA1 was 42.1, 41.2, and 73.3%, respectively; among patients with SCA2 was 38.5, 27.3, and 100%, respectively; and among patients with SCA3 was 18.2, 37.5, and 88.9%, respectively. The differences between the subgroups of SCAs were not statistically significant. Conclusions: BAER was the most frequent abnormality in SCA types 1, 2, and 3; abnormalities of mSSEP were comparable in the three SCAs; whereas, abnormality of VEP was less often noted in SCA3.

  17. Giant early components of somatosensory evoked potentials to tibial nerve stimulation in cortical myoclonus.

    Science.gov (United States)

    Anzellotti, Francesca; Onofrj, Marco; Bonanni, Laura; Saracino, Antonio; Franciotti, Raffaella

    2016-01-01

    Enlarged cortical components of somatosensory evoked potentials (giant SEPs) recorded by electroencephalography (EEG) and abnormal somatosensory evoked magnetic fields (SEFs) recorded by magnetoencephalography (MEG) are observed in the majority of patients with cortical myoclonus (CM). Studies on simultaneous recordings of SEPs and SEFs showed that generator mechanism of giant SEPs involves both primary sensory and motor cortices. However the generator sources of giant SEPs have not been fully understood as only one report describes clearly giant SEPs following lower limb stimulation. In our study we performed a combined EEG-MEG recording on responses elicited by electric median and tibial nerve stimulation in a patient who developed consequently to methyl bromide intoxication CM with giant SEPs to median and tibial nerve stimuli. SEPs wave shapes were identified on the basis of polarity-latency components (e.g. P15-N20-P25) as defined by earlier studies and guidelines. At EEG recording, the SEP giant component did not appear in the latency range of the first cortical component for median nerve SEP (N20), but appeared instead in the range of the P37 tibial nerve SEP, which is currently identified as the first cortical component elicited by tibial nerve stimuli. Our MEG and EEG SEPs recordings also showed that components in the latency range of P37 were preceded by other cortical components. These findings suggest that lower limb P37 does not correspond to upper limb N20. MEG results confirmed that giant SEFs are the second component from both tibial (N43m-P43m) and median (N27m-P27m) nerve stimulation. MEG dipolar sources of these giant components were located in the primary sensory and motor area.

  18. Interatomic Potentials via the Effective Action Formalism

    Science.gov (United States)

    Rasamny, M.; Valiev, M.; Fernando, G. W.

    1998-03-01

    We present a method for the generation of interatomic potentials from first principles calculations using the marat>effective action formalism which leads to a systematic definition for effective two-body interatomic potentials. We do this by reducing the fully interacting system to an auxilliary system which interacts via a two-body interatomic potential. This definition can be trivially extended to higher order interatomic potentials. Unlike other approaches, our interatomic potentials are obtained from a sampling of configuration space pertaining to the thermodynamic environment of interest.

  19. Acute stress increases depolarization-evoked glutamate release in the rat prefrontal/frontal cortex: the dampening action of antidepressants.

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    Laura Musazzi

    2010-01-01

    Full Text Available Behavioral stress is recognized as a main risk factor for neuropsychiatric diseases. Converging evidence suggested that acute stress is associated with increase of excitatory transmission in certain forebrain areas. Aim of this work was to investigate the mechanism whereby acute stress increases glutamate release, and if therapeutic drugs prevent the effect of stress on glutamate release.Rats were chronically treated with vehicle or drugs employed for therapy of mood/anxiety disorders (fluoxetine, desipramine, venlafaxine, agomelatine and then subjected to unpredictable footshock stress. Acute stress induced marked increase in depolarization-evoked release of glutamate from synaptosomes of prefrontal/frontal cortex in superfusion, and the chronic drug treatments prevented the increase of glutamate release. Stress induced rapid increase in the circulating levels of corticosterone in all rats (both vehicle- and drug-treated, and glutamate release increase was blocked by previous administration of selective antagonist of glucocorticoid receptor (RU 486. On the molecular level, stress induced accumulation of presynaptic SNARE complexes in synaptic membranes (both in vehicle- and drug-treated rats. Patch-clamp recordings of pyramidal neurons in the prefrontal cortex revealed that stress increased glutamatergic transmission through both pre- and postsynaptic mechanisms, and that antidepressants may normalize it by reducing release probability.Acute footshock stress up-regulated depolarization-evoked release of glutamate from synaptosomes of prefrontal/frontal cortex. Stress-induced increase of glutamate release was dependent on stimulation of glucocorticoid receptor by corticosterone. Because all drugs employed did not block either elevation of corticosterone or accumulation of SNARE complexes, the dampening action of the drugs on glutamate release must be downstream of these processes. This novel effect of antidepressants on the response to stress

  20. Screening action potentials: The power of light

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    Lars eKaestner

    2011-07-01

    Full Text Available Action potentials reflect the concerted activity of all electrogenic constituents in the plasma membrane during the excitation of a cell. Therefore, the action potential is an integrated readout and a promising parameter to detect electrophysiological failures or modifications thereof in diagnosis as well as in drug screens. Cellular action potentials can be recorded by optical approaches. To fulfill the pre-requirements to scale up for e.g. pharmacological screens the following preparatory work has to be provided: (i model cells under investigation need to represent target cells in the best possible manner; (ii optical sensors that can be either small molecule dyes or genetically encoded potential probes need to provide a reliable readout with minimal interaction with the naive behavior of the cells and (iii devices need to be capable to stimulate the cells, read out the signals with the appropriate speed as well as provide the capacity for a sufficient throughput. Here we discuss several scenarios for all three categories in the field of cardiac physiology and pharmacology and provide a perspective to use the power of light in screening cardiac action potentials.

  1. Long-latency auditory evoked potentials with verbal and nonverbal stimuli,

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    Sheila Jacques Oppitz

    2015-12-01

    Full Text Available ABSTRACT INTRODUCTION: Long-latency auditory evoked potentials represent the cortical activity related to attention, memory, and auditory discrimination skills. Acoustic signal processing occurs differently between verbal and nonverbal stimuli, influencing the latency and amplitude patterns. OBJECTIVE: To describe the latencies of the cortical potentials P1, N1, P2, N2, and P3, as well as P3 amplitude, with different speech stimuli and tone bursts, and to classify them in the presence and absence of these data. METHODS: A total of 30 subjects with normal hearing were assessed, aged 18-32 years old, matched by gender. Nonverbal stimuli were used (tone burst; 1000 Hz - frequent and 4000 Hz - rare; and verbal (/ba/ - frequent; /ga/, /da/, and /di/ - rare. RESULTS: Considering the component N2 for tone burst, the lowest latency found was 217.45 ms for the BA/DI stimulus; the highest latency found was 256.5 ms. For the P3 component, the shortest latency with tone burst stimuli was 298.7 with BA/GA stimuli, the highest, was 340 ms. For the P3 amplitude, there was no statistically significant difference among the different stimuli. For latencies of components P1, N1, P2, N2, P3, there were no statistical differences among them, regardless of the stimuli used. CONCLUSION: There was a difference in the latency of potentials N2 and P3 among the stimuli employed but no difference was observed for the P3 amplitude.

  2. New composite index based on midlatency auditory evoked potential and electroencephalographic parameters to optimize correlation with propofol effect site concentration - Comparison with bispectral index and solitary used fast extracting auditory evoked potential index

    NARCIS (Netherlands)

    Vereecke, HEM; Vasquez, PM; Jensen, EW; Thas, O; Vandenbroecke, R; Mortier, EP; Struys, MMRF

    Background: This study investigates the accuracy of a composite index, the A-Line (R) auditory evoked potentials index version 1.6 (AAI(1.6); Danmeter A/S, Odense, Denmark), as a measure of cerebral anesthetic drug effect in a model for predicting a calculated effect site concentration of propofol

  3. Excitatory amino acid receptor-mediated transmission of somatosensory evoked potentials in the rat thalamus.

    Science.gov (United States)

    Klockgether, T

    1987-12-01

    1. To examine the role of excitatory amino acid receptors in the rat ventrobasal thalamic nucleus (v.b.t.n.) for the transmission of cortical somatosensory evoked potentials (s.e.p.s), potentials were recorded from the somatosensory cortex of barbiturate-anaesthetized and of unanaesthetized awake rats. The effects of microapplications of the selective N-methyl-D-aspartate (NMDA) antagonist (-)-2-amino-7-phosphono-heptanoate ((-)AP7) and the broad-spectrum excitatory amino acid antagonist 1-(p-chlorobenzoyl)-piperazine-2,3-dicarboxylate (pCB-PzDA) into the thalamus on the amplitudes and latencies of cortical potentials were measured. 2. To define the receptor specificity of local microinjections of (-)AP7 and pCB-PzDA electroencephalogram (e.e.g.) recordings were made from the immediate vicinity of the injection cannula within the thalamus. (-)AP7 selectively antagonized epileptic discharges induced by NMDA, but not those by kainate, whereas pCB-PzDA antagonized epileptic discharges induced by both. 3. In both anaesthetized and unanaesthetized rats, microapplications of pCB-PzDA into the thalamus suppressed transmission of cortical potentials as indicated by a decrease of their amplitudes and an increase of their peak latencies. Further experiments in anaesthetized rats showed that pCB-PzDA exerted its effects in a dose-dependent and site-specific way. 4. In both anaesthetized and unanaesthetized rats, microapplications of (-)AP7 into the ventrobasal thalamus did not affect cortical potentials. 5. These results are consistent with the assumption that an excitatory amino acid serves as transmitter at thalamic synapses mediating transmission of cortical potentials, and that this transmitter interacts preferentially with non-NMDA receptors.

  4. Introducing the Action Potential to Psychology Students

    Science.gov (United States)

    Simon-Dack, Stephanie L.

    2014-01-01

    For this simple active learning technique for teaching, students are assigned "roles" and act out the process of the action potential (AP), including the firing threshold, ion-specific channels for ions to enter and leave the cell, diffusion, and the refractory period. Pre-post test results indicated that students demonstrated increased…

  5. Long-Term Visuo-Gustatory Appetitive and Aversive Conditioning Potentiate Human Visual Evoked Potentials

    DEFF Research Database (Denmark)

    Christoffersen, Gert Rene Juul; Laugesen, Jakob Lund; Møller, Per

    2017-01-01

    cortical regions—from primary visual areas and into the inferior temporal gyrus (ITG). These learning-induced changes were seen after both appetitive and aversive training while a sham trained control group showed no changes. It is concluded that long-term visuo-gustatory conditioning potentiated the N2-P3...

  6. P3-5: Temporal Interactions between Binocular Inputs in Visual Evoked-Potentials

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    Sunkyue Kim

    2012-10-01

    Full Text Available The interaction between neural activity driven by inputs through the two eyes were examined using visual evoked-potentials (VEP in normal human subjects. VEP recordings were obtained at the occipital electrodes using binocularly asynchronous pattern-reversal checkerboard stimuli: The patter-reversal times for the two eyes differed by 0, ±50, ±150, or ±350 ms, with the positive stimulus-onset asynchrony (SOA meaning that the right-eye reversal occurred first. For comparison, monocular VEPs were also obtained using trial conditions where the checkerboard pattern-reversals were shown to only one eye, while a blank field to the other. The VEPs of the various trial conditions were analyzed using both temporal and frequency analysis methods. Three observations were made: First, the N75 amplitude was significantly reduced in the ±50 ms SOA conditions. Second, on ±150 ms and ± ms SOA conditions, a negative potential was observed over the period when the stimuli were binocularly incongruent. Third, the alpha-band power was reduced and the beta-band power increased on asynchronous conditions, compared to the synchronous patter-reversal. These findings show that activities of binocular neurons in the visual cortices get modulated by binocular incongruity in the asynchronous pattern-reversal stimuli. Our stimuli may prove valuable in elucidating neural mechanisms of integration of binocular visual inputs, especially when combined with brain source-localization techniques and compared between normal subjects and patients with dysfunction in binocular vision.

  7. [The use of somatosensory evoked potentials for cortical localization during surgical operations].

    Science.gov (United States)

    Recuero, E

    Identification of the cortical areas of Roland, by means of anatomical references seen on craniotomy, with a view to their conservation during surgical operations, is found to be associated with a high rate of error which may reach 50% with experienced surgeons. Somatosensory evoked potentials (PESS) following stimulation of the median nerve may easily be recorded using electrodes situated directly over the cerebral cortex of patients under general anaesthesia. To obtain this recording, a bipolar set-up of a series of between 6 and 10 electrodes in line one centimetre apart allows identification, by means of phase opposition, of the cortical zones, usually the parietal zone adjacent to the sulcus of Roland, where these potentials are generated. Identification of motor sites (area 4) can be obtained by electrical stimulation of the cerebral cortex, although we have rejected this type of exploration because of its technical difficulty and possible undesirable effects. We consider that, when at surgical operation the cortical area corresponding to the median nerve is identified, and care taken not to damage the cortex 2 cm rostrally, excellent results may be obtained, reducing the sequelae which may occur with this type of surgery.

  8. Sensitivity of offset and onset cortical auditory evoked potentials to signals in noise.

    Science.gov (United States)

    Baltzell, Lucas S; Billings, Curtis J

    2014-02-01

    The purpose of this study was to determine the effects of SNR and signal level on the offset response of the cortical auditory evoked potential (CAEP). Successful listening often depends on how well the auditory system can extract target signals from competing background noise. Both signal onsets and offsets are encoded neurally and contribute to successful listening in noise. Neural onset responses to signals in noise demonstrate a strong sensitivity to signal-to-noise ratio (SNR) rather than signal level; however, the sensitivity of neural offset responses to these cues is not known. We analyzed the offset response from two previously published datasets for which only the onset response was reported. For both datasets, CAEPs were recorded from young normal-hearing adults in response to a 1000-Hz tone. For the first dataset, tones were presented at seven different signal levels without background noise, while the second dataset varied both signal level and SNR. Offset responses demonstrated sensitivity to absolute signal level in quiet, SNR, and to absolute signal level in noise. Offset sensitivity to signal level when presented in noise contrasts with previously published onset results. This sensitivity suggests a potential clinical measure of cortical encoding of signal level in noise.

  9. Influence of delta9-tetrahydrocannabinol and cannabidiol on photically evoked after-discharge potentials.

    Science.gov (United States)

    Turkanis, S A; Chiu, P; Borys, H K; Karler, R

    1977-04-29

    Two cannabinoids, delta9-tetrahydrocannabinol and cannabidiol, and several reference drugs were compared relative to their effects in a recently developed anticonvulsant test system, the after-discharge potentials of the visually evoked response; the potentials were recorded electrophysiologically from electrodes permanently mounted over the visual cortices of conscious rats. In anticonvulsant doses, trimethadione and ethosuximide produced an extensive depression of after-discharge activity, whereas diphenylhydantoin and cannabidiol exerted no such effect. In contrast, anticonvulsant doses of delta9-tetrahydrocannabinol and subconvulsant doses of pentylenetetrazol markedly increased after-discharge activity, which may represent a manifestation of their central nervous system excitatory properties. The data from the present study support our previously published ovservations from several other anticonvulsant tests that indicate the anticonvulsant characteristics of cannabidiol resemble those of diphenylhydantoin rather than those of trimethadione and that the central excitatory properties of delta9-tetrahydrocannabinol distinguish it from cannabidiol. The results consistently suggest that the cannabinoids will be effective against grand mal but not absence seizures.

  10. Research on steady-state visual evoked potentials in 3D displays

    Science.gov (United States)

    Chien, Yu-Yi; Lee, Chia-Ying; Lin, Fang-Cheng; Huang, Yi-Pai; Ko, Li-Wei; Shieh, Han-Ping D.

    2015-05-01

    Brain-computer interfaces (BCIs) are intuitive systems for users to communicate with outer electronic devices. Steady state visual evoked potential (SSVEP) is one of the common inputs for BCI systems due to its easy detection and high information transfer rates. An advanced interactive platform integrated with liquid crystal displays is leading a trend to provide an alternative option not only for the handicapped but also for the public to make our lives more convenient. Many SSVEP-based BCI systems have been studied in a 2D environment; however there is only little literature about SSVEP-based BCI systems using 3D stimuli. 3D displays have potentials in SSVEP-based BCI systems because they can offer vivid images, good quality in presentation, various stimuli and more entertainment. The purpose of this study was to investigate the effect of two important 3D factors (disparity and crosstalk) on SSVEPs. Twelve participants participated in the experiment with a patterned retarder 3D display. The results show that there is a significant difference (p-valuefuture.

  11. Hemisection spinal cord injury in rat: The value of intraoperative somatosensory evoked potential monitoring

    Science.gov (United States)

    Cloud, Beth A.; Ball, Bret G.; Chen, Bingkun; Knight, Andrew M.; Hakim, Jeffrey S.; Ortiz, Ana M.; Windebank, Anthony J.

    2012-01-01

    Techniques used to produce partial spinal cord injuries in animal models have the potential for creating variability in lesions. The amount of tissue affected may influence the functional outcomes assessed in the animals. The recording of somatosensory evoked potentials (SSEPs) may be a valuable tool for assessing the extent of lesion applied in animal models of traumatic spinal cord injury (SCI). Intraoperative tibial SSEP recordings were assessed during surgically induced lateral thoracic hemisection SCI in Sprague-Dawley rats. The transmission of SSEPs, or lack thereof, was determined and compared against the integrity of the dosal funiculi on each side of the spinal cord upon histological sectioning. An association was found between the presence of an SSEP signal and presence of intact dorsal funiculus tissue. The relative risk is 4.50 (95% confidence interval: 1.83 to 11.08) for having an intact dorsal funiculus when the ipsilateral SSEP was present compared to when it was absent. Additionally, the amount of spared spinal cord tissue correlates with final functional assessments at nine weeks post injury: BBB (linear regression, R2 = 0.618, p assess extent of lesion and reduce variability between animals in experimental studies of SCI. PMID:22960163

  12. Short-duration transient visual evoked potential for objective measurement of refractive errors.

    Science.gov (United States)

    Anand, Aashish; De Moraes, Carlos Gustavo V; Teng, Christopher C; Liebmann, Jeffrey M; Ritch, Robert; Tello, Celso

    2011-12-01

    This study examined effects of uncorrected refractive errors (RE) in a short-duration transient visual evoked potential (SD t-VEP) system and investigated their role for objective measurement of RE. Refractive errors were induced by means of trial lenses in 35 emmetropic subjects. A synchronized single-channel EEG was recorded for emmetropia, and each simulated refractive state to generate 21 VEP responses for each subject. P100 amplitude (N75 trough to P100 peak) and latency were identified by an automated post-signal processing algorithm. Induced hypermetropia and myopia correlated strongly with both P100 amplitude and latency. To minimize the effect of baseline shift and waveform fluctuations, a VEP scoring system, based on software-derived P100 latency, amplitude and waveform quality, was used to estimate the RE. Using the VEP scores, a single VEP response had a high sensitivity and specificity for discerning emmetropia, small RE (<2 diopter) within a 2 diopter range and large RE (2-14 diopter) within a 4 diopter range. The VEP scoring system has a potential for objective screening of RE and for a more accurate 3-step objective refraction.

  13. Neurophysiological assessment of perceived image quality using steady-state visual evoked potentials

    Science.gov (United States)

    Bosse, Sebastian; Acqualagna, Laura; Porbadnigk, Anne K.; Curio, Gabriel; Müller, Klaus-Robert; Blankertz, Benjamin; Wiegand, Thomas

    2015-09-01

    An approach to the neural measurement of perceived image quality using electroencephalography (EEG) is presented. 6 different images were tested on 6 different distortion levels. The distortions were introduced by a hybrid video encoder. The presented study consists of two parts: In a first part, subjects were asked to evaluate the quality of the test stimuli behaviorally during a conventional psychophysical test using a degradation category rating procedure. In a second part, subjects were presented undistorted and distorted texture images in a periodically alternating fashion at a fixed frequency. This alternating presentation elicits so called steady-state visual evoked potentials (SSVEP) as a brain response that can be measured on the scalp. The amplitude of modulations in the brain signals is significantly and strongly negatively correlated with the magnitude of visual impairment reported by the subjects. This neurophysiological approach to image quality assessment may potentially lead to a more objective evaluation, as behavioral approaches suffer from drawbacks such as biases, inter-subject variances and limitations to test duration.

  14. Cognitive Evoked Potential Measurement, P300, in a group of healthy Colombian individuals

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    Natalia Gutiérrez Giraldo

    2013-05-01

    Full Text Available Cognitive evoked potentials are electrophysiological measurements of cognitive functions. Cognitivepotential P300 is specifically related to attention processes. Objetive: the aim of this studywas to establish reference values for latency and amplitude of P300 wave in the Colombian population and determine their variability with age, gender and education of the subjects. Methods:we studied 122 healthy subjects between 6 and 80 years, are practical potential measurementmethodology as odd-ball, in leads Cz and Pz. Results: we were able to establish reference valuesfor different age groups, and statistical significance was found with which the latency of P300wave increases with the age of individuals, and instead thereof the amplitude tends to decrease.Similarly to correlate latency and amplitude was shown an inverse relationship between them.Conclusions: no differences were found for latency and wave amplitude, gender-related or schoolsubjects as well as no difference was found when measuring the Pz derivation obtained comparedwith the wave in lead Cz.

  15. Influence of narcotics on luminance and frequency modulated visual evoked potentials in rats.

    Science.gov (United States)

    Jehle, T; Ehlken, D; Wingert, K; Feuerstein, T J; Bach, M; Lagrèze, W A

    2009-06-01

    Quantification of visual function is essential for the impact of disease models and their treatment. Recently, we introduced a chronic implant model to record visual evoked potentials (VEP) in awake Brown-Norway rats. Here, we investigated the hemispheric distribution of VEP after monocular stimulation, the chronic electrode implantation and the influence of commonly used anesthetics. Potentials were recorded by electrodes, implanted epidurally over the superior colliculus. The entire visual field of the rat was stimulated. Flicker stimuli were modulated in luminance with a modulation depth from 5 to 80% at 7.5 Hz and flashes with a modulation depth of >95% in a frequency range of 2.9-38 Hz. Recordings were constant over 9 days. When one eye was blinded, the potentials recorded from the contralateral side were not affected, while the potentials of the ipsilateral side were markedly reduced. Further, potentials of awake animals were compared with those receiving general anesthetics. For one group of rats (n = 8), we administered isoflurane by inhalation in five concentrations. Four different groups (n = 7-11) were given choralhydrate (200 and 400 mg/kg) and the combination of ketamine/xyaline (65/7 or 130/14 mg/kg, respectively) intraperitoneally. Isoflurane depressed the VEP in a concentration-dependent manner. Treatment with chloralhydrate and ketamine/xyaline increased the VEP at low concentrations and depressed it in high concentrations. The new VEP paradigm assesses distinct qualities of contrast vision in rats. All tested narcotics alter VEP amplitudes and can be avoided.

  16. [Changes of somatosensory and transcranial magnetic stimulation motor evoked potentials in experimental spinal cord injury].

    Science.gov (United States)

    Hou, Yong; Nie, Lin; Liu, Li-hong; Shao, Jun; Yuan, Yong-jian

    2008-03-18

    To study the changes of somatosensory evoked potential (SEP) and transcranial magnetic simulation motor evoked potential (TMS-MEP) in experimental spinal cord injury (SCI). Thirty-two rabbits were randomly divided into 4 equal groups. All rabbits were anesthetized for 90 min. A group (Group A) underwent only laminectomy of T12 without SCI, stimulation with different intensities was used to induce SEP and TMS-MEP to determine the most appropriate stimulation intensity. The EPs were recorded before and after the operation. The other 3 groups underwent laminectomy of T12 to expose the dura, and a spinal cord compressing apparatus weighing 40 g was put on the intact dura and dorsal surface of spinal cord underneath for 5, 15, and 30 min respectively (Groups B, C, and D). SEP and TMS-MEP were detected after anesthesia, after exposure of spinal cord, and 5 and 30 min, 1 and 6 h, and 1, 3, and 7 d. The latency and amplitude of each wave were measured. The data were analyzed by analysis of variance, t-test and linear correlation. Tarlov behavior score was used to assess the motor function before the operation and 1, 3, and 7 days after SCI. It was found that 100% intensity stimulus obtained stable and reliable MEP waves. Anesthetic did not influence the EPs. The amplitude of SEP began to decrease 5 min after SCI and the latency began to increase 30 min after SCI. And both the amplitude and latency, especially the former, of MEP began to significantly change 5 min after SCI. The latency levels of SEP and MEP increased and the amplitude decreased after compression time-dependently during a certain range of time (all P TMS-MEP are very sensitive to SCI, in particular, the change of amplitude is more sensitive then the latency change and can more accurately reflect the degree of SCI. Combination of SEP and TMS-MEP objectively reflects the SCI degree. EP measurement, as a noninvasive technique, has great value in monitoring spinal cord function.

  17. Evoked potentials after painful cutaneous electrical stimulation depict pain relief during a conditioned pain modulation.

    Science.gov (United States)

    Höffken, Oliver; Özgül, Özüm S; Enax-Krumova, Elena K; Tegenthoff, Martin; Maier, Christoph

    2017-08-29

    Conditioned pain modulation (CPM) evaluates the pain modulating effect of a noxious conditioning stimulus (CS) on another noxious test stimulus (TS), mostly based solely on subjective pain ratings. We used painful cutaneous electrical stimulation (PCES) to induce TS in a novel CPM-model. Additionally, to evaluate a more objective parameter, we recorded the corresponding changes of cortical evoked potentials (PCES-EP). We examined the CPM-effect in 17 healthy subjects in a randomized controlled cross-over design during immersion of the non-dominant hand into 10 °C or 24 °C cold water (CS). Using three custom-built concentric surface electrodes, electrical stimuli were applied on the dominant hand, inducing pain of 40-60 on NRS 0-100 (TS). At baseline, during and after CS we assessed the electrically induced pain intensity and electrically evoked potentials recorded over the central electrode (Cz). Only in the 10 °C-condition, both pain (52.6 ± 4.4 (baseline) vs. 30.3 ± 12.5 (during CS)) and amplitudes of PCES-EP (42.1 ± 13.4 μV (baseline) vs. 28.7 ± 10.5 μV (during CS)) attenuated during CS and recovered there after (all p pain ratings during electrical stimulation and amplitudes of PCES-EP correlated significantly with each other (r = 0.5) and with CS pain intensity (r = 0.5). PCES-EPs are a quantitative measure of pain relief, as changes in the electrophysiological response are paralleled by a consistent decrease in subjective pain ratings. This novel CPM paradigm is a feasible method, which could help to evaluate the function of the endogenous pain modulation processes. German Clinical Trials Register DRKS-ID: DRKS00012779 , retrospectively registered on 24 July 2017.

  18. Objective detection and localization of multiple sclerosis lesions on magnetic resonance brainstem images: validation with auditory evoked potentials.

    Science.gov (United States)

    Stufflebeam, S M; Levine, R A; Gardner, J C; Fullerton, B C; Furst, M; Rosen, B R

    2000-01-01

    To develop an objective method for detecting multiple sclerosis (MS) brainstem lesions, magnetic resonance (MR) images (multiple planar, spin-echo, acquired in three planes of section) of sixteen MS patients and fourteen normal subjects were analyzed with an algorithm that detected regions with a relatively increased intensity on both a spin-echo image and a T2 image. To be considered a lesion, such regions had to overlap in at least two orthogonal planes. Using a digitized atlas of the human brainstem, the lesion locations were mapped with respect to the brainstem anatomy. This method was evaluated by comparing the location of MS lesions with the brainstem auditory evoked potentials obtained from these subjects. Brainstem lesions were detected in five MS patients; four had lesions impinging upon the auditory system and one did not. All four had abnormal evoked potentials. The fourteen normal subjects, the one MS patient with brainstem lesions outside the auditory pathway, and the eleven other MS patients with no brainstem lesions all had normal evoked potentials. The requirement that lesions be detected in at least two planes of section greatly improved the specificity of the algorithm. The consistency between the MR and brainstem auditory evoked potentials results supports the validity of this imaging analysis algorithm for objectively localizing brainstem lesions.

  19. Predictive value of neurological examination for early cortical responses to somatosensory evoked potentials in patients with postanoxic coma

    NARCIS (Netherlands)

    Bouwes, A.; Binnekade, J.M.; Verbaan, B.W.; Zandbergen, E.G.J.; Koelman, J.H.T.M.; Weinstein, H.C.; Hijdra, A.; van Horn, J.

    2012-01-01

    Bilateral absence of cortical N20 responses of median nerve somatosensory evoked potentials (SEP) predicts poor neurological outcome in postanoxic coma after cardiopulmonary resuscitation (CPR). Although SEP is easy to perform and available in most hospitals, it is worthwhile to know how

  20. Visual evoked potential in RCS rats with Okayama University-type retinal prosthesis (OUReP™) implantation.

    Science.gov (United States)

    Alamusi; Matsuo, Toshihiko; Hosoya, Osamu; Uchida, Tetsuya

    2017-06-01

    Photoelectric dye-coupled polyethylene film, designated Okayama University type-retinal prosthesis or OUReP™, generates light-evoked surface electric potentials and stimulates neurons. The dye-coupled films or plain films were implanted subretinally in both eyes of 10 Royal College of Surgeons rats with hereditary retinal dystrophy at the age of 6 weeks. Visual evoked potentials in response to monocular flashing light stimuli were recorded from cranially-fixed electrodes, 4 weeks and 8 weeks after the implantation. After the recording, subretinal film implantation was confirmed histologically in 7 eyes with dye-coupled films and 7 eyes with plain films. The recordings from these 7 eyes in each group were used for statistical analysis. The amplitudes of visual evoked potentials in the consecutive time points from 125 to 250 ms after flash were significantly larger in the 7 eyes with dye-coupled film implantation, compared to the 7 eyes with plain film implantation at 8 weeks after the implantation (P prosthesis, gave rise to visual evoked potential in response to flashing light.

  1. Selective activation of heteromeric SK channels contributes to action potential repolarization in mouse atrial myocytes.

    Science.gov (United States)

    Hancock, Jane M; Weatherall, Kate L; Choisy, Stéphanie C; James, Andrew F; Hancox, Jules C; Marrion, Neil V

    2015-05-01

    Activation of small conductance calcium-activated potassium (SK) channels is proposed to contribute to repolarization of the action potential in atrial myocytes. This role is controversial, as these cardiac SK channels appear to exhibit an uncharacteristic pharmacology. The objectives of this study were to resolve whether activation of SK channels contributes to atrial action potential repolarization and to determine the likely subunit composition of the channel. The effect of 2 SK channel inhibitors was assessed on outward current evoked in voltage clamp and on action potential duration in perforated patch and whole-cell current clamp recording from acutely isolated mouse atrial myocytes. The presence of SK channel subunits was assessed using immunocytochemistry. A significant component of outward current was reduced by the SK channel blockers apamin and UCL1684. Block by apamin displayed a sensitivity indicating that this current was carried by homomeric SK2 channels. Action potential duration was significantly prolonged by UCL1684, but not by apamin. This effect was accompanied by an increase in beat-to-beat variability and action potential triangulation. This pharmacology was matched by that of expressed heteromeric SK2-SK3 channels in HEK293 cells. Immunocytochemistry showed that atrial myocytes express both SK2 and SK3 channels with an overlapping expression pattern. Only proposed heteromeric SK2-SK3 channels are physiologically activated to contribute to action potential repolarization, which is indicated by the difference in pharmacology of evoked outward current and prolongation of atrial action potential duration. The effect of blocking this channel on the action potential suggests that SK channel inhibition during cardiac function has the potential to be proarrhythmic. Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  2. A study on dynamic model of steady-state visual evoked potentials.

    Science.gov (United States)

    Zhang, Shangen; Han, Xu; Chen, Xiaogang; Wang, Yijun; Gao, Shangkai; Gao, Xiaorong

    2018-04-04

    Significant progress has been made in the past two decades to considerably improve the performance of steady-state visual evoked potential (SSVEP)-based brain-computer interface (BCI). However, there are still some unsolved problems that may help us to improve BCI performance, one of which is that our understanding of the dynamic process of SSVEP is still superficial, especially for the transient-state response. This study introduced an antiphase stimulation method (antiphase: phase 0/π), which can simultaneously separate and extract SSVEP and event-related potential (ERP) signals from EEG, and eliminate the interference of ERP to SSVEP. Based on the SSVEP signals obtained by the antiphase stimulation method, the envelope of SSVEP was extracted by the Hilbert transform, and the dynamic model of SSVEP was quantitatively studied by mathematical modeling. The step response of a second-order linear system was used to fit the envelope of SSVEP, and its characteristics were represented by four parameters with physical and physiological meanings: one was amplitude related, one was latency related and two were frequency related. This study attempted to use pre-stimulation paradigms to modulate the dynamic model parameters, and quantitatively analyze the results by applying the dynamic model to further explore the pre-stimulation methods that had the potential to improve BCI performance. The results showed that the dynamic model had good fitting effect with SSVEP under three pre-stimulation paradigms. The test results revealed that the parameters of SSVEP dynamic models could be modulated by the pre-stimulation baseline luminance, and the gray baseline luminance pre-stimulation obtained the highest performance. This study proposed a dynamic model which was helpful to understand and utilize the transient characteristics of SSVEP. This study also found that pre-stimulation could be used to adjust the parameters of SSVEP model, and had the potential to improve the performance

  3. Multifocal Visual Evoked Potential in Eyes With Temporal Hemianopia From Chiasmal Compression: Correlation With Standard Automated Perimetry and OCT Findings.

    Science.gov (United States)

    Sousa, Rafael M; Oyamada, Maria K; Cunha, Leonardo P; Monteiro, Mário L R

    2017-09-01

    To verify whether multifocal visual evoked potential (mfVEP) can differentiate eyes with temporal hemianopia due to chiasmal compression from healthy controls. To assess the relationship between mfVEP, standard automated perimetry (SAP), and Fourier domain-optical coherence tomography (FD-OCT) macular and peripapillary retinal nerve fiber layer (RNFL) thickness measurements. Twenty-seven eyes with permanent temporal visual field (VF) defects from chiasmal compression on SAP and 43 eyes of healthy controls were submitted to mfVEP and FD-OCT scanning. Multifocal visual evoked potential was elicited using a stimulus pattern of 60 sectors and the responses were averaged for the four quadrants and two hemifields. Optical coherence tomography macular measurements were averaged in quadrants and halves, while peripapillary RNFL thickness was averaged in four sectors around the disc. Visual field loss was estimated in four quadrants and each half of the 24-2 strategy test points. Multifocal visual evoked potential measurements in the two groups were compared using generalized estimated equations, and the correlations between mfVEP, VF, and OCT findings were quantified. Multifocal visual evoked potential-measured temporal P1 and N2 amplitudes were significantly smaller in patients than in controls. No significant difference in amplitude was observed for nasal parameters. A significant correlation was found between mfVEP amplitudes and temporal VF loss, and between mfVEP amplitudes and the corresponding OCT-measured macular and RNFL thickness parameters. Multifocal visual evoked potential amplitude parameters were able to differentiate eyes with temporal hemianopia from controls and were significantly correlated with VF and OCT findings, suggesting mfVEP is a useful tool for the detection of visual abnormalities in patients with chiasmal compression.

  4. Use of auditory evoked potentials for intra-operative awareness in anesthesia: a consciousness-based conceptual model.

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    Dong, Xuebao; Suo, Puxia; Yuan, Xin; Yao, Xuefeng

    2015-01-01

    Auditory evoked potentials (AEPs) have been used as a measure of the depth of anesthesia during the intra-operative process. AEPs are classically divided, on the basis of their latency, into first, fast, middle, slow, and late components. The use of auditory evoked potential has been advocated for the assessment of Intra-operative awareness (IOA), but has not been considered seriously enough to universalize it. It is because we have not explored enough the impact of auditory perception and auditory processing on the IOA phenomena as well as on the subsequent psychological impact of IOA on the patient. More importantly, we have seldom tried to look at the phenomena of IOP from the perspective of consciousness itself. This perspective is especially important because many of IOA phenomena exist in the subconscious domain than they do in the conscious domain of explicit recall. Two important forms of these subconscious manifestations of IOA are the implicit recall phenomena and post-operative dreams related to the operation. Here, we present an integrated auditory consciousness-based model of IOA. We start with a brief description of auditory awareness and the factors affecting it. Further, we proceed to the evaluation of conscious and subconscious information processing by auditory modality and how they interact during and after intra-operative period. Further, we show that both conscious and subconscious auditory processing affect the IOA experience and both have serious psychological implications on the patient subsequently. These effects could be prevented by using auditory evoked potential during monitoring of anesthesia, especially the mid-latency auditory evoked potentials (MLAERs). To conclude our model with present hypothesis, we propose that the use of auditory evoked potential should be universal with general anesthesia use in order to prevent the occurrences of distressing outcomes resulting from both conscious and subconscious auditory processing during

  5. Brain evoked potentials to noxious sural nerve stimulation in sciatalgic patients.

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    Willer, J C; De Broucker, T; Barranquero, A; Kahn, M F

    1987-07-01

    In sciatalgic patients and before any treatment, the goal of this work was to compare the amplitude of the late component (N150-P220) of the brain evoked potential (BEP) between resting pain-free conditions and a neurological induced pain produced by the Lasègue manoeuvre. The study was carried out with 8 inpatients affected with a unilateral sciatica resulting from an X-ray identified dorsal root compression from discal origin. The sural nerve was electrically stimulated at the ankle level while BEPs were recorded monopolarly from the vertex. The stimulus intensity eliciting a liminal nociceptive reflex response in a knee-flexor muscle associated with a liminal pain was selected for this study. Both normal and affected side were alternatively stimulated during several conditions of controls and of Lasègue's manoeuvres performed on the normal and on the affected side. Results show that the Lasègue manoeuvre performed on the affected side induced a significant increase in the amplitude of N150-P220; performed on the normal side, this same manoeuvre resulted in a significant decrease of the N150-P220 amplitude. These variations were observed whatever was the side (normal or affected) under sural nerve stimulation. The possible neural mechanisms of these changes and clinical implications of these data are then discussed.

  6. Recovery function of the human brain stem auditory-evoked potential.

    Science.gov (United States)

    Kevanishvili, Z; Lagidze, Z

    1979-01-01

    Amplitude reduction and peak latency prolongation were observed in the human brain stem auditory-evoked potential (BEP) with preceding (conditioning) stimulation. At a conditioning interval (CI) of 5 ms the alteration of BEP was greater than at a CI of 10 ms. At a CI of 10 ms the amplitudes of some BEP components (e.g. waves I and II) were more decreased than those of others (e.g. wave V), while the peak latency prolongation did not show any obvious component selectivity. At a CI of 5 ms, the extent of the amplitude decrement of individual BEP components differed less, while the increase in the peak latencies of the later components was greater than that of the earlier components. The alterations of the parameters of the test BEPs at both CIs are ascribed to the desynchronization of intrinsic neural events. The differential amplitude reduction at a CI of 10 ms is explained by the different durations of neural firings determining various effects of desynchronization upon the amplitudes of individual BEP components. The decrease in the extent of the component selectivity and the preferential increase in the peak latencies of the later BEP components observed at a CI of 5 ms are explained by the intensification of the mechanism of the relative refractory period.

  7. Sudden Bilateral Hearing Loss After Cervical and Ocular Vestibular Evoked Myogenic Potentials.

    Science.gov (United States)

    Mattingly, Jameson K; Portnuff, Cory D F; Hondorp, Brian M; Cass, Stephen P

    2015-07-01

    Cervical and ocular vestibular evoked myogenic potentials (cVEMPs and oVEMPs) are commonly used in evaluation of neurotologic disorders. We present a case of sudden bilateral hearing loss immediately after oVEMP and cVEMP testing. The hearing loss did not recover. To our knowledge, no previous case reports discuss sudden hearing loss, especially bilateral, associated with VEMP testing. A single patient with sudden bilateral hearing loss that has persisted after cVEMP and oVEMP. The patient had a history of chronic daily dizziness. She underwent vestibular function testing that included cVEMP and oVEMP testing. A significant bilateral sensorineural hearing loss was noted immediately after cVEMP and oVEMP testing and confirmed with audiometric testing. Despite the use of oral steroids, her hearing loss did not recover. Serial audiograms, calculated maximum total sound energies to each ear. Pre-VEMP versus post-VEMP audiograms show increased thresholds and decreased word recognition scores; total sound energy delivered to each ear shows significant sound exposure. Although VEMP testing is thought to be safe and well tolerated, a significant amount of sound can be delivered to the cochlea, and certain individuals may be susceptible to acoustic trauma at these levels. We recommend limits for VEMP stimuli levels and attention to total sound exposure when multiple trials are used.

  8. Cervical and ocular vestibular-evoked myogenic potentials in acute vestibular neuritis.

    Science.gov (United States)

    Shin, Byoung-Soo; Oh, Sun-Young; Kim, Ji Soo; Kim, Tae-Woo; Seo, Man-Wook; Lee, Hyung; Park, Young-Ae

    2012-02-01

    To clarify the origin and afferent pathways of short-latency ocular vestibular-evoked myogenic potential (oVEMP) in response to air-conducted sound (ACS), we evaluated cervical (cVEMP) and ocular VEMPs in patients with vestibular neuritis (VN). In response to air-conducted tone burst, the oVEMP and cVEMP were measured in 60 healthy controls and in 41 patients with acute VN. The VN selectively involved the superior vestibular nerve (superior VN) in 30 patients, affected the inferior vestibular nerve only (inferior VN) in three and damaged both superior and inferior vestibular nerve branches in eight. All 30 patients with superior VN presented normal cVEMPs, indicating preservation of the saccular receptors and their afferents in the inferior vestibular nerve. However, the oVEMP was abnormal in all patients with superior VN. By contrast, the patients with inferior VN showed normal oVEMP and abnormal cVEMP. These dissociations in the abnormalities of cVEMP and oVEMP in patients with VN selectively involving the superior or inferior vestibular nerve suggest that the origin of the vestibular nerve afferents of oVEMP differ from those of cVEMP. The oVEMP in response to ACS may be mediated by the superior vestibular nerve, probably due to an activation of the utricular receptors. Copyright © 2011 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  9. Cognitive evoked potentials and central auditory processing in children with reading and writing disorders.

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    Wiemes, Gislaine Richter Minhoto; Kozlowski, Lorena; Mocellin, Marcos; Hamerschmidt, Rogério; Schuch, Luiz Henrique

    2012-06-01

    Learning disorders are often magnified by auditory processing disorders (APD). This paper aims to verify whether individuals with reading and writing disorders and P300 latencies above the average also present altered Staggered Spondaic Word (SSW) and speech-in-noise test results suggestive of APD. This is a cross-sectional cohort study. Twenty-one individuals with reading and writing disorders aged between 7 and 14 years were enrolled. All subjects had normal findings on ENT examination, audiological tests, and brainstem auditory evoked potentials. The average P300 latency (334,25 ms) of all patients was picked as a cutoff point to divide the subjects into two groups: group A with latencies above 335 ms, and group B with latencies below 335 ms. Individuals in group A underwent SSW and speech-in-noise testing. Altered results in the SSW and speech-in-noise tests suggestive of APD were found in the group of individuals with reading and writing disorders with P300 latencies above 335 ms.

  10. Preservation of motor maps with increased motor evoked potential amplitude threshold in RMT determination.

    Science.gov (United States)

    Lucente, Giuseppe; Lam, Steven; Schneider, Heike; Picht, Thomas

    2018-02-01

    Non-invasive pre-surgical mapping of eloquent brain areas with navigated transcranial magnetic stimulation (nTMS) is a useful technique linked to the improvement of surgical planning and patient outcomes. The stimulator output intensity and subsequent resting motor threshold determination (rMT) are based on the motor-evoked potential (MEP) elicited in the target muscle with an amplitude above a predetermined threshold of 50 μV. However, a subset of patients is unable to achieve complete relaxation in the target muscles, resulting in false positives that jeopardize mapping validity with conventional MEP determination protocols. Our aim is to explore the feasibility and reproducibility of a novel mapping approach that investigates how an increase of the MEP amplitude threshold to 300 and 500 μV affects subsequent motor maps. Seven healthy subjects underwent motor mapping with nTMS. RMT was calculated with the conventional methodology in conjunction with experimental 300- and 500-μV MEP amplitude thresholds. Motor mapping was performed with 105% of rMT stimulator intensity using the FDI as the target muscle. Motor mapping was possible in all patients with both the conventional and experimental setups. Motor area maps with a conventional 50-μV threshold showed poor correlation with 300-μV (α = 0.446, p motor area maps (α = 0.974, p motor area mapping with nTMS without losing precision.

  11. Relationship between vitamin D deficiency and visually evoked potentials in multiple sclerosis.

    Science.gov (United States)

    López-Méndez, P; Sosa-Henríquez, M; Ruiz-Pérez, Á

    2016-05-01

    To evaluate the possible relationship between serum 25-OH vitamin D levels and visually evoked potentials (VEP) in patients with multiple sclerosis (MS), residents in the south zone of Gran Canaria. The study included 49 patients with MS, on whom 25-OH-vitamin D was determined, along with VEP, and a neurological examination to determine incapacity. Clinical variables, such as a history of optic neuritis were recorded. The mean value of 25-OH-vitamin D of the patients was 28.1±9.5ng/ml. The VEP latency was 119.1±23.2ms and the amplitude, 8.5±4.4 μV. Patients with a higher 25-OH-vitamin D had a greater number of outbreaks in the year prior to the study (P=.049), and those with vitamin D deficiency and previous optic neuritis showed no reduction in the amplitude of the VEP (P=.006). Patients with vitamin D deficiency have lower clinical activity of the MS and show no axonal involvement in VEP after having suffered optic neuritis. These relationships, although statistically significant, do not seem clinically plausible, thus new studies are needed to try and confirm this possible relationship. Copyright © 2016 Sociedad Española de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.

  12. Time-frequency component analysis of somatosensory evoked potentials in rats.

    Science.gov (United States)

    Zhang, Zhi-Guo; Yang, Jun-Lin; Chan, Shing-Chow; Luk, Keith Dip-Kei; Hu, Yong

    2009-02-09

    Somatosensory evoked potential (SEP) signal usually contains a set of detailed temporal components measured and identified in a time domain, giving meaningful information on physiological mechanisms of the nervous system. The purpose of this study is to measure and identify detailed time-frequency components in normal SEP using time-frequency analysis (TFA) methods and to obtain their distribution pattern in the time-frequency domain. This paper proposes to apply a high-resolution time-frequency analysis algorithm, the matching pursuit (MP), to extract detailed time-frequency components of SEP signals. The MP algorithm decomposes a SEP signal into a number of elementary time-frequency components and provides a time-frequency parameter description of the components. A clustering by estimation of the probability density function in parameter space is followed to identify stable SEP time-frequency components. Experimental results on cortical SEP signals of 28 mature rats show that a series of stable SEP time-frequency components can be identified using the MP decomposition algorithm. Based on the statistical properties of the component parameters, an approximated distribution of these components in time-frequency domain is suggested to describe the complex SEP response. This study shows that there is a set of stable and minute time-frequency components in SEP signals, which are revealed by the MP decomposition and clustering. These stable SEP components have specific localizations in the time-frequency domain.

  13. Identification of detailed time-frequency components in somatosensory evoked potentials.

    Science.gov (United States)

    Zhang, Zhiguo; Luk, Keith D K; Hu, Yong

    2010-06-01

    Somatosensory evoked potential (SEP) usually contains a set of detailed temporal components measured and identified in time domain, providing meaningful information on physiological mechanisms of the nervous system. The purpose of this study is to reveal complex and fine time-frequency features of SEP in time-frequency domain using advanced time-frequency analysis (TFA) and pattern classification methods. A high-resolution TFA algorithm, matching pursuit (MP), was proposed to decompose a SEP signal into a string of elementary waves and to provide a time-frequency feature description of the waves. After a dimension reduction by principle component analysis (PCA), a density-guided K-means clustering was followed to identify typical waves existed in SEP. Experimental results on posterior tibial nerve SEP signals of 50 normal adults showed that a series of typical waves were discovered in SEP using the proposed MP decomposition and clustering methods. The statistical properties of these SEP waves were examined and their representative waveforms were synthesized. The identified SEP waves provided a comprehensive and detailed description of time-frequency features of SEP.

  14. Time-frequency component analysis of somatosensory evoked potentials in rats

    Directory of Open Access Journals (Sweden)

    Luk Keith

    2009-02-01

    Full Text Available Abstract Background Somatosensory evoked potential (SEP signal usually contains a set of detailed temporal components measured and identified in a time domain, giving meaningful information on physiological mechanisms of the nervous system. The purpose of this study is to measure and identify detailed time-frequency components in normal SEP using time-frequency analysis (TFA methods and to obtain their distribution pattern in the time-frequency domain. Methods This paper proposes to apply a high-resolution time-frequency analysis algorithm, the matching pursuit (MP, to extract detailed time-frequency components of SEP signals. The MP algorithm decomposes a SEP signal into a number of elementary time-frequency components and provides a time-frequency parameter description of the components. A clustering by estimation of the probability density function in parameter space is followed to identify stable SEP time-frequency components. Results Experimental results on cortical SEP signals of 28 mature rats show that a series of stable SEP time-frequency components can be identified using the MP decomposition algorithm. Based on the statistical properties of the component parameters, an approximated distribution of these components in time-frequency domain is suggested to describe the complex SEP response. Conclusion This study shows that there is a set of stable and minute time-frequency components in SEP signals, which are revealed by the MP decomposition and clustering. These stable SEP components have specific localizations in the time-frequency domain.

  15. Preoperative and postoperative evaluation of somatosensorial evoked potentials of upper extremities in cervical intervertebral disc herniation.

    Science.gov (United States)

    Umur, Ahmet Sukru; Selcuki, Mehmet; Selcuki, Deniz; Temiz, Cuneyt; Akbasak, Aytac

    2013-01-01

    This study aims to determine the dysfunction caused by existing pathological condition in structures involved in the transfer of sensory functions of the neural system in cervical disc herniation, and to establish whether or not the level and degree of this anatomical damage can be anticipated by SEP (Somatosensorial Evoked Potentials). We compared the obtained SEP values for statistical significance using the Friedman Variation Analysis. In parameters with statistical significance, the Wilcoxon Signed Rank test was used to identify when significant improvements occurred. The study found that the statistical data of the latency of the N14 wave originating from the dorsal column nuclei of the medulla spinalis and dorsal column gray matter improved (p < 0.05) in the postoperative period compared with the preoperative values. Using the Wilcoxon Signed Rank test, we studied postoperative months separately in regard to the difference in the latency of the N14 wave, and found the statistically significant improvement to be marked particularly in months 3 and 6 postoperatively (p < 0.05). In conclusion, we suggest that SEP is a useful tool to check the functional condition of the dorsal spinal column. The benefit of the SEP utilization is the ability to determine the severity of the pathological condition preoperatively and follow the patient's functional postoperative improvement.

  16. [Evoked potentials in movement epilepsy (a report on 4 observations) (author's transl)].

    Science.gov (United States)

    Paty, J; Deliac-Narvarte, M M; Fontan, D; Loiseau, P

    1978-09-01

    A study of evoked potentials; visual (V.E.P.) auditory (A.E.P), and somatosensorial (S.E.P.) in 4 cases of movement epilepsy. Their correlation to clinical findings (provoking factors, control of the attacks), electroencephalographic and neuroradiological (scanner) data, shows that two types of information can be obtained: lesional and functional. Three types of modification can be described: a) the topographically limited changes in E.P. depend on lesional localization; b) the increase in amplitude of the late components and of the post-discharge of the E.P. ("paroxystical" aspect) appear to be a characteristic common to all epilepsies, whatever the mechanism; c) the abnormal exaggeration of the E.P. during voluntary movement seems to be a dynamic element peculiar to movement epilepsy. The information given by E.P.'s in some well-defined cases of epilepsy suggest that it is possible to draw conclusions from tests of the capacity for sensory-motor control to enable functional therapy of some attacks.

  17. Brain volume analyses and somatosensory evoked potentials in multiple system atrophy.

    Science.gov (United States)

    Miyatake, Satoko; Mochizuki, Hitoshi; Naka, Tetsuji; Ugawa, Yoshikazu; Tanabe, Hajime; Kuzume, Daisuke; Suzuki, Mikiya; Ogata, Katsuhisa; Kawai, Mitsuru

    2010-03-01

    We investigated a progression of brain atrophy and somatosensory system dysfunction in multiple system atrophy (MSA). Subjects were 21 MSA patients [12 MSA-C (cerebellar type) and 9 MSA-P (parkinsonism type)]. The relative volumes of cerebrum, brainstem and cerebellum to the intracranial volume were obtained from three-dimensional computed tomography (3D-CT) of the brain. The median nerve somatosensory evoked potentials (SEPs) were recorded, and the latencies and amplitudes of N9, N11, P13/14, N20 and P25 components were measured. We studied correlations between brain volumes, SEP and clinical features. The brainstem and cerebellar atrophies were aggravated with progression of the disease. The central sensory conduction time (CSCT) was progressively prolonged in parallel with the disease duration irrespective of the actual age of the patients. In MSA patients, the volume reductions of cerebellum and brainstem could be one of structural markers of disease progression, and the sensory pathway is progressively involved with the progression of disease processes.

  18. Auditory evoked potentials: predicting speech therapy outcomes in children with phonological disorders

    Directory of Open Access Journals (Sweden)

    Renata Aparecida Leite

    2014-03-01

    Full Text Available OBJECTIVES: This study investigated whether neurophysiologic responses (auditory evoked potentials differ between typically developed children and children with phonological disorders and whether these responses are modified in children with phonological disorders after speech therapy. METHODS: The participants included 24 typically developing children (Control Group, mean age: eight years and ten months and 23 children clinically diagnosed with phonological disorders (Study Group, mean age: eight years and eleven months. Additionally, 12 study group children were enrolled in speech therapy (Study Group 1, and 11 were not enrolled in speech therapy (Study Group 2. The subjects were submitted to the following procedures: conventional audiological, auditory brainstem response, auditory middle-latency response, and P300 assessments. All participants presented with normal hearing thresholds. The study group 1 subjects were reassessed after 12 speech therapy sessions, and the study group 2 subjects were reassessed 3 months after the initial assessment. Electrophysiological results were compared between the groups. RESULTS: Latency differences were observed between the groups (the control and study groups regarding the auditory brainstem response and the P300 tests. Additionally, the P300 responses improved in the study group 1 children after speech therapy. CONCLUSION: The findings suggest that children with phonological disorders have impaired auditory brainstem and cortical region pathways that may benefit from speech therapy.

  19. Steady-state visually evoked potential correlates of human body perception.

    Science.gov (United States)

    Giabbiconi, Claire-Marie; Jurilj, Verena; Gruber, Thomas; Vocks, Silja

    2016-11-01

    In cognitive neuroscience, interest in the neuronal basis underlying the processing of human bodies is steadily increasing. Based on functional magnetic resonance imaging studies, it is assumed that the processing of pictures of human bodies is anchored in a network of specialized brain areas comprising the extrastriate and the fusiform body area (EBA, FBA). An alternative to examine the dynamics within these networks is electroencephalography, more specifically so-called steady-state visually evoked potentials (SSVEPs). In SSVEP tasks, a visual stimulus is presented repetitively at a predefined flickering rate and typically elicits a continuous oscillatory brain response at this frequency. This brain response is characterized by an excellent signal-to-noise ratio-a major advantage for source reconstructions. The main goal of present study was to demonstrate the feasibility of this method to study human body perception. To that end, we presented pictures of bodies and contrasted the resulting SSVEPs to two control conditions, i.e., non-objects and pictures of everyday objects (chairs). We found specific SSVEPs amplitude differences between bodies and both control conditions. Source reconstructions localized the SSVEP generators to a network of temporal, occipital and parietal areas. Interestingly, only body perception resulted in activity differences in middle temporal and lateral occipitotemporal areas, most likely reflecting the EBA/FBA.

  20. Recovery from parkinson syndrome and prolonged visually evoked potentials in hepatic encephalopathy.

    Science.gov (United States)

    Finsterer, Josef; Bernauer, Elisabeth

    2005-03-01

    The combination of Parkinson syndrome (PS) and prolonged visually evoked potentials (VEPs) in a single patient with hepatic encephalopathy (HE) has not been reported. A 52-year-old male with chronic HE developed PS in early 2001. Treatment with L-DOPA was only of minimal effect. In August 2001 he was admitted because of worsening PS and HE. There was anemia, hyperlipidaemia, markedly elevated liver-function-parameters, hyperammonemia, elevated resting-lactate, steatosis hepatis and hepatomegalia. VEPs showed markedly prolonged P100-latencies. Under L-DOPA, pramipexol, L-ornithin-L-aspartate, paromomycin-sulfate, and lactulose liver-function-parameters normalized and PS markedly improved. In February 2003, VEPs were normal. L-DOPA was discontinued by the patient in April 2003 and pramipexol in December 2003. Since then PS did not recur. This case shows that HE may go along with reversible PS and prolonged VEPs. Under adequate therapy liver-function-parameters and VEPs normalize and PS disappears.

  1. Impact of loudness dependency of auditory evoked potentials on the panic response to CCK-4.

    Science.gov (United States)

    Eser, Daniela; Leicht, Gregor; Baghai, Thomas; Pogarell, Oliver; Schüle, Cornelius; Karch, Susanne; Nothdurfter, Caroline; Rupprecht, Rainer; Mulert, Christoph

    2009-01-01

    Experimental panic induction with cholecystokinin-tetrapeptide (CCK-4) has been established as a model to study the pathophysiology of panic disorder. In line with the serotonin (5-HT)-hypothesis of panic disorder it has been suggested that the panicogenic effects of CCK-4 are mediated in part through the 5-HT system. The analysis of the loudness dependency of the auditory evoked potentials (LDAEP) is a valid non-invasive indicator of central serotonergic activity. We investigated the correlation between LDAEP and behavioral, cardiovascular and neuroendocrine panic responses to CCK-4in 77 healthy volunteers and explored whether differences in LDAEP paralleled subjective panic severity. Behavioral panic responses were measured with the panic symptom scale (PSS). Heart rate and ACTH/cortisol plasma concentrations were assessed concomitantly. LDAEP did not differ between panickers and nonpanickers. Furthermore, LDAEP did not correlate with the behavioral panic response. However, a significant positive correlation between LDAEP and CCK-4 induced HPA-axis activation, which was uniform in panickers and nonpanickers, could be detected. The psychological effects of CCK-4 rather are mediated by neurotransmitters others than the endogenous 5-HT system. However, the extent of the neuroendocrine activation related to the CCK-4 panic provocation was correlated with the LDAEP, thereby suggesting that central 5-HT mechanisms are involved in the HPA-axis activation during this challenge paradigm.

  2. Evaluation of an automated analysis for pain-related evoked potentials

    Directory of Open Access Journals (Sweden)

    Wulf Michael

    2017-09-01

    Full Text Available This paper presents initial steps towards an auto-mated analysis for pain-related evoked potentials (PREP to achieve a higher objectivity and non-biased examination as well as a reduction in the time expended during clinical daily routines. While manually examining, each epoch of an en-semble of stimulus-locked EEG signals, elicited by electrical stimulation of predominantly intra-epidermal small nerve fibers and recorded over the central electrode (Cz, is in-spected for artifacts before calculating the PREP by averag-ing the artifact-free epochs. Afterwards, specific peak-latencies (like the P0-, N1 and P1-latency are identified as certain extrema in the PREP’s waveform. The proposed automated analysis uses Pearson’s correlation and low-pass differentiation to perform these tasks. To evaluate the auto-mated analysis’ accuracy its results of 232 datasets were compared to the results of the manually performed examina-tion. Results of the automated artifact rejection were compa-rable to the manual examination. Detection of peak-latencies was more heterogeneous, indicating some sensitivity of the detected events upon the criteria used during data examina-tion.

  3. Sensory gating revisited: relation between brain oscillations and auditory evoked potentials in schizophrenia.

    Science.gov (United States)

    Brockhaus-Dumke, Anke; Mueller, Ralf; Faigle, Ulrich; Klosterkoetter, Joachim

    2008-02-01

    Disturbances of auditory information processing have repeatedly been shown in schizophrenia. To contribute to a better understanding of the neurophysiological underpinnings of habituation in auditory processing and its disturbance in schizophrenia we used three different approaches to analyze auditory evoked responses, namely phase-locking (PL) analyses, single trial amplitudes, and averaged event-related potentials (P50 and N100). Given that brain oscillations reflect the neuronal correlates of information processing we hypothesized that PL and amplitudes reflect even more essential parts of auditory processing than the averaged ERP responses. In 32 schizophrenia patients and 32 matched controls EEG was continuously recorded using an auditory paired click paradigm. PL of the lower frequency bands (alpha and theta) was significantly reduced in patients whereas no significant differences were present in higher frequencies (gamma and beta). Alpha and theta PL and amplitudes showed a marked increase after the first click and to a minor degree after the second one. This habituation was more prominent in controls whereas in schizophrenia patients the response to both clicks differed only slightly. N100 suppression was significantly reduced in schizophrenia patients whereas no group differences were present with respect to the P50. This corresponded to the finding that gamma mostly contributed to the prediction of the P50 response and theta mostly to the N100 response. Our data showed that analyzing phase and amplitude in single trials provides more information on auditory information processing and reflects differences between schizophrenia patients and controls better than analyzing the averaged ERP responses.

  4. Do Event-Related Evoked Potentials Reflect Apathy Tendency and Motivation?

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    Hiroyuki Takayoshi

    2018-01-01

    Full Text Available Apathy is a mental state of diminished motivation. Although the reward system as the foundation of the motivation in the human brain has been studied extensively with neuroimaging techniques, the electrophysiological correlates of motivation and apathy have not been fully explored. Thus, in 14 healthy volunteers, we examined whether event-related evoked potentials (ERP obtained during a simple number discrimination task with/without rewards reflected apathy tendency and a reward-dependent tendency, which were assessed separately using the apathy scale and the temperament and character inventory (TCI. Participants were asked to judge the size of a number, and received feedback based on their performance in each trial. The P3 amplitudes related to the feedback stimuli increased only in the reward condition. Furthermore, the P2 amplitudes related to the negative feedback stimuli in the reward condition had a positive correlation with the reward-dependent tendency in TCI, whereas the P3 amplitudes related to the positive feedback stimuli had a negative correlation with the apathy score. Our result suggests that the P2 and P3 ERPs to reward-related feedback stimuli are modulated in a distinctive manner by the motivational reward dependence and apathy tendency, and thus the current paradigm may be useful for investigating the brain activity associated with motivation.

  5. Do Event-Related Evoked Potentials Reflect Apathy Tendency and Motivation?

    Science.gov (United States)

    Takayoshi, Hiroyuki; Onoda, Keiichi; Yamaguchi, Shuhei

    2018-01-01

    Apathy is a mental state of diminished motivation. Although the reward system as the foundation of the motivation in the human brain has been studied extensively with neuroimaging techniques, the electrophysiological correlates of motivation and apathy have not been fully explored. Thus, in 14 healthy volunteers, we examined whether event-related evoked potentials (ERP) obtained during a simple number discrimination task with/without rewards reflected apathy tendency and a reward-dependent tendency, which were assessed separately using the apathy scale and the temperament and character inventory (TCI). Participants were asked to judge the size of a number, and received feedback based on their performance in each trial. The P3 amplitudes related to the feedback stimuli increased only in the reward condition. Furthermore, the P2 amplitudes related to the negative feedback stimuli in the reward condition had a positive correlation with the reward-dependent tendency in TCI, whereas the P3 amplitudes related to the positive feedback stimuli had a negative correlation with the apathy score. Our result suggests that the P2 and P3 ERPs to reward-related feedback stimuli are modulated in a distinctive manner by the motivational reward dependence and apathy tendency, and thus the current paradigm may be useful for investigating the brain activity associated with motivation. PMID:29445331

  6. Toward brain-computer interface based wheelchair control utilizing tactually-evoked event-related potentials

    Science.gov (United States)

    2014-01-01

    Background People with severe disabilities, e.g. due to neurodegenerative disease, depend on technology that allows for accurate wheelchair control. For those who cannot operate a wheelchair with a joystick, brain-computer interfaces (BCI) may offer a valuable option. Technology depending on visual or auditory input may not be feasible as these modalities are dedicated to processing of environmental stimuli (e.g. recognition of obstacles, ambient noise). Herein we thus validated the feasibility of a BCI based on tactually-evoked event-related potentials (ERP) for wheelchair control. Furthermore, we investigated use of a dynamic stopping method to improve speed of the tactile BCI system. Methods Positions of four tactile stimulators represented navigation directions (left thigh: move left; right thigh: move right; abdomen: move forward; lower neck: move backward) and N = 15 participants delivered navigation commands by focusing their attention on the desired tactile stimulus in an oddball-paradigm. Results Participants navigated a virtual wheelchair through a building and eleven participants successfully completed the task of reaching 4 checkpoints in the building. The virtual wheelchair was equipped with simulated shared-control sensors (collision avoidance), yet these sensors were rarely needed. Conclusion We conclude that most participants achieved tactile ERP-BCI control sufficient to reliably operate a wheelchair and dynamic stopping was of high value for tactile ERP classification. Finally, this paper discusses feasibility of tactile ERPs for BCI based wheelchair control. PMID:24428900

  7. Cervical Vestibular Evoked Myogenic Potential in Hypoglossal Nerve Schwannoma: A Case Report.

    Science.gov (United States)

    Rajasekaran, Aravind Kumar; Savardekar, Amey Rajan; Shivashankar, Nagaraja Rao

    2018-02-01

    Schwannoma of the hypoglossal nerve is rare. This case report documents an atypical abnormality of the cervical vestibular evoked myogenic potential (cVEMP) in a patient with schwannoma of the hypoglossal nerve. The observed abnormality was attributed to the proximity of the hypoglossal nerve to the spinal accessory nerve in the medullary cistern and base of the skull. To report cVEMP abnormality in a patient with hypoglossal nerve schwannoma and provide an anatomical correlation for this abnormality. Case report. A 44-yr-old woman. Pure-tone and speech audiometry, tympanometry, acoustic stapedial reflex, auditory brainstem response, and cVEMP testing were performed. The audiological test results were normal except for the absence of cVEMP on the lesion side (right). A cVEMP abnormality indicating a compromised spinal accessory nerve was observed in a patient with hypoglossal nerve schwannoma. This case report highlights the importance of recording cVEMP in relevant neurological conditions and provides clinical proof for the involvement of the spinal accessory nerve in the vestibulocollic reflex pathway. American Academy of Audiology

  8. [Superior canal dehiscence syndrome : Diagnosis with vestibular evoked myogenic potentials and fremitus nystagmus. German version].

    Science.gov (United States)

    Gürkov, R; Jerin, C; Flatz, W; Maxwell, R

    2018-01-23

    Superior canal dehiscence syndrome (SCDS) is a relatively rare neurotological disorder that is characterized by a heterogeneous clinical picture. Recently, vestibular evoked myogenic potential (VEMP) measurementwas established for the diagnosis of SCDS. In the present study, a case series of patients with SCDS were analyzed, with a focus on VEMP. Four patients with SCDS were prospectively examined with ocular VEMP (oVEMP) and cervical VEMP (cVEMP). The clinical features and the standard audiovestibular test battery results are summarized and analyzed. The diagnostic accuracy of VEMP testing is evaluated. The increased oVEMP amplitudes had a specificity of 100% in this patient population. All patients had normal caloric function and head impulse testing. The Tullio sign was observed in two patients. Three patients had autophony. The airbone gap was not greater than 10 dB in any of the patients. Two patients had marked fremitus nystagmus. All patients had a bony dehiscence of the superior semicircular canal on computed tomography imaging. The subjective and clinical features in this case series of SCDS patients were heterogeneous. However, objective oVEMP testing had the highest diagnostic value. Furthermore, we describe a new diagnostic clinical sign: fremitus nystagmus.

  9. Superior canal dehiscence syndrome : Diagnosis with vestibular evoked myogenic potentials and fremitus nystagmus.

    Science.gov (United States)

    Gürkov, R; Jerin, C; Flatz, W; Maxwell, R

    2018-01-01

    Superior canal dehiscence syndrome (SCDS) is a relatively rare neurotological disorder that is characterized by a heterogeneous clinical picture. Recently, vestibular evoked myogenic potential (VEMP) measurement was established for the diagnosis of SCDS. In the present study, a case series of patients with SCDS were analyzed, with a focus on VEMP. Four patients with SCDS were prospectively examined with ocular VEMP (oVEMP) and cervical VEMP (cVEMP). The clinical features and the standard audiovestibular test battery results are summarized and analyzed. The diagnostic accuracy of VEMP testing is evaluated. The increased oVEMP amplitudes had a specificity of 100% in this patient population. All patients had normal caloric function and head impulse testing. The Tullio sign was observed in two patients. Three patients had autophony. The air-bone gap was not greater than 10 dB in any of the patients. Two patients had marked fremitus nystagmus. All patients had a bony dehiscence of the superior semicircular canal on computed tomography imaging. The subjective and clinical features in this case series of SCDS patients were heterogeneous. However, objective oVEMP testing had the highest diagnostic value. Furthermore, we describe a new diagnostic clinical sign: fremitus nystagmus.

  10. The effect of increased intracranial pressure on vestibular evoked myogenic potentials in superior canal dehiscence syndrome.

    Science.gov (United States)

    Janky, Kristen L; Zuniga, M Geraldine; Schubert, Michael C; Carey, John P

    2015-04-01

    To determine if vestibular evoked myogenic potential (VEMP) responses change during inversion in patients with superior canal dehiscence syndrome (SCDS) compared to controls. Sixteen subjects with SCDS (mean: 43, range 30-57 years) and 15 age-matched, healthy subjects (mean: 41, range 22-57 years) completed cervical VEMP (cVEMP) in response to air conduction click stimuli and ocular VEMP (oVEMP) in response to air conduction 500 Hz tone burst stimuli and midline tap stimulation. All VEMP testing was completed in semi-recumbent and inverted conditions. SCDS ears demonstrated significantly larger oVEMP peak-to-peak amplitudes in comparison to normal ears in semi-recumbency. While corrected cVEMP peak-to-peak amplitudes were larger in SCDS ears; this did not reach significance in our sample. Overall, there was not a differential change in o- or cVEMP amplitude with inversion between SCDS and normal subjects. Postural-induced changes in o- and cVEMP responses were measured in the steady state regardless of whether the labyrinth was intact or dehiscent. VEMP responses are blunted during inversion. Although steady-state measurements of VEMPs during inversion do not increase diagnostic accuracy for SCDS, the findings suggest that inversion may provide more general insights into the equilibration of pressures between intracranial and intralabyrinthine fluids. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  11. A software module for the adaptive estimation of steady state auditory evoked potentials.

    Science.gov (United States)

    Middleton, S; Goli, A; Ziarani, A K

    2006-01-01

    A graphical user interface (GUI) implementing a novel technique of fast estimation of steady state auditory evoked potentials (SSAEPs) for rapid assessment of the functionality of the human auditory nervous system is presented. The proposed signal estimator has shown great promise in the fast extraction of weak signals buried under large amounts of noise such as the case with SSAEP signals. Currently, the main technical impediment in the widespread clinical use of the SSAEP testing for hearing assessment is the excessively long measurement time needed for the estimation process due to the presence of large amounts of background noise. The presented software module that is publicly disseminated through the Internet is meant to facilitate the use of an efficient signal processing technique by the hearing researchers. The software environment allows for loading previously recorded SSAEP signals into the workspace for analysis. Moreover, it enables the user to add simulated SSAEP signals to the background EEG for the purpose of testing the capability of the underlying signal processing algorithm.

  12. Effect of epidural clonidine on somatosensory evoked potentials to dermatomal stimulation

    DEFF Research Database (Denmark)

    Lund, C; Hansen, O B; Kehlet, H

    1989-01-01

    The effect of lumbar epidural clonidine 150 micrograms on early (less than 0.5 s) somatosensory evoked potentials (SEP) to electrical stimulation of the L1 and S1 dermatomes was examined in twelve cancer patients. Epidural clonidine led to a minor but significant decrease in amplitude of two...... systolic and diastolic blood pressures decreased from 118 +/- 4/72 +/- 5 mmHg to 99 +/- 5/60 +/- 3 mmHg (P less than 0.01), respectively. It is concluded that epidural clonidine has a minor effect on the early SEPs to electrical dermatomal stimulation. Additionally, a pronounced effect on cancer pain...... components (N1 and N3) following S1 stimulation while SEP latency was prolonged only in the P1 and P3 components (P less than 0.05). In all patients the pain score decreased, mean score at rest from 4.9 +/- 0.5 to 0.6 +/- 0.2 and during mobilization from 7.4 +/- 0.6 to 1.3 +/- 0.5 (P less than 0.01). Mean...

  13. Clinical implication of cervical vestibular evoked myogenic potentials in benign paroxysmal positional vertigo.

    Science.gov (United States)

    Chang, Mun Young; Shin, Ji Ho; Oh, Kyung Hyun; Hong, Young Ho; Mun, Seog-Kyun

    2017-02-01

    To evaluate the value of cervical vestibular evoked myogenic potential (cVEMP) as a prognostic factor for benign paroxysmal positional vertigo (BPPV). We reviewed 65 patients with BPPV who underwent cVEMP. Patients were divided into two groups according to resistance to the repositioning maneuver. Univariable and multivariable analyses were performed with age, gender, affected semicircular canal, affected side and cVEMP parameters to find the associated factors for resistance to the repositioning maneuver. From univariable analysis, cVEMP interaural amplitude difference (IAD) ratio, the affected semicircular canal and the affected side showed a better association (p<0.10) with resistance to the repositioning maneuver. With multivariable analysis, decreased cVEMP IAD ratio at the affected side (⩽-25%) (p=0.043, OR=4.934) and the posterior semicircular canal (p=0.049, OR=3.780) remained as associated factors. Decreased cVEMP IAD ratio at the affected side is associated with resistance to the repositioning maneuver. BPPV patients with decreased cVEMP IAD ratio at the affected side have a higher likelihood of their BPPV persisting after a single repositioning maneuver. cVEMP test may provide a prognosis of BPPV. A decreased cVEMP IAD ratio at the affected side may be prognostic of BPPV not resolving after a single repositioning maneuver. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

  14. Language plasticity in aphasics after recovery: evidence from slow evoked potentials.

    Science.gov (United States)

    Spironelli, Chiara; Angrilli, Alessandro; Pertile, Marco

    2008-04-01

    With the present experiment we sought to investigate brain plasticity underlying language recovery in a group of seventeen patients with non-fluent aphasia mainly caused by stroke. Patients were screened along three domains of measures: analysis of linguistic components by the Aachener Aphasie Test, combined mapping of their lesion from CT/MRI scans, and functional measure of the reorganized linguistic processes by means of mapping of slow evoked potentials. The spatial dimension and temporal dynamics of word processing were measured in three tasks, Phonological, Semantic and Orthographic. Compared with the matched control group, patients showed relative inhibition (decreased negativity) of left central regions in perisylvian areas, which were damaged in most subjects. In addition, reorganization of linguistic functions occurred within the left hemisphere both at frontal and posterior sites corresponding to spared brain regions. Correlations between linguistic lateralization in the three tasks and AAT subtests point to functional reorganization of phonological processes over left frontal sites and dysfunctional reorganization of semantic processing over left posterior regions.

  15. Diffusion tensor imaging of the inferior colliculus and brainstem auditory-evoked potentials in preterm infants

    International Nuclear Information System (INIS)

    Reiman, Milla; Lehtonen, Liisa; Lapinleimu, Helena; Parkkola, Riitta; Johansson, Reijo; Jaeaeskelaeinen, Satu K.; Kujari, Harry; Haataja, Leena

    2009-01-01

    Preterm and low-birth-weight infants have an increased risk of sensorineural hearing loss. Brainstem auditory-evoked potentials (BAEP) are an effective method to detect subtle deficits in impulse conduction in the auditory pathway. Abnormalities on diffusion tensor imaging (DTI) have been shown to be associated with perinatal white-matter injury and reduced fractional anisotropy (FA) has been reported in patients with sensorineural hearing loss. To evaluate the possibility of a correlation between BAEP and DTI of the inferior colliculus in preterm infants. DTI at term age and BAEP measurements were performed on all very-low-birth-weight or very preterm study infants (n=56). FA and apparent diffusion coefficient (ADC) of the inferior colliculus were measured from the DTI. Shorter BAEP wave I, III, and V latencies and I-III and I-V intervals and higher wave V amplitude correlated with higher FA of the inferior colliculus. The association between the DTI findings of the inferior colliculus and BAEP responses suggests that DTI can be used to assess the integrity of the auditory pathway in preterm infants. (orig.)

  16. Emotions and neural processing of respiratory sensations investigated with respiratory-related evoked potentials.

    Science.gov (United States)

    von Leupoldt, Andreas; Chan, Pei-Ying S; Esser, Roland W; Davenport, Paul W

    2013-04-01

    Patients with respiratory diseases such as asthma and chronic obstructive pulmonary disease frequently experience respiratory sensations, which are often perceived as unpleasant or threatening. However, the accurate perception of respiratory sensations is important for the management and treatment of these diseases. Emotions can substantially influence the perception of respiratory sensations and might affect the course of respiratory diseases, but the underlying neural mechanisms are poorly understood. The respiratory-related evoked potential (RREP) recorded from the electroencephalogram is a noninvasive technique that allowed first studies to examine the impact of emotions on the neural processing of respiratory sensations. In this review, we will briefly introduce the importance of the perception of respiratory sensations and the influence of emotions on respiratory perception. We then provide an overview on the technique of RREP and present a systematic review on recent findings using this technique in the context of emotions. The evidence currently available from studies in healthy individuals suggests that short-lasting emotional states and anxiety affect the later RREP components (N1, P2, P3) related to higher-order neural processing of respiratory sensations, but not the earlier RREP components (Nf, P1) related to first-order sensory processing. We conclude with a discussion of the implications of this work for future research that needs to focus on respiratory patient groups and the associated clinical outcomes.

  17. Ocular vestibular evoked myogenic potential testing for the prognosis of Bell's palsy.

    Science.gov (United States)

    Yang, Chul Won; Kim, Sang Hoon; Yeo, Seung Geun; Park, Moon Suh; Byun, Jae Yong

    2017-02-01

    oVEMP could be a useful tool for predicting the prognosis of Bell's palsy comparable to ENoG and H-B grade. Several previous studies have reported cases of Bell's palsy with vestibular function disorder. The basic hypothesis behind this effect lies in the close proximity of the vestibular and facial nerves in the internal auditory canal (IAC). Therefore, the aim of this study was to investigate the correlation between Bell's palsy prognosis and ocular vestibular evoked myogenic potentials (oVEMPs). Total 104 consecutive patients who were diagnosed with Bell?s palsy from January 2012 to December 2014 were enrolled. Patients were divided into complete recovery group and incomplete recovery group. All of patients underwent oVEMP recordings within 1 week after disease onset. For the evaluation of correlation between H-B grades, ENoG, oVEMP and Recovery of Bell?s palsy, logistic regression analysis was performed. The mean value of ocular vemp asymmetry was significantly higher in the incomplete recovery group than the complete recovery group (p < 0.05). No association was found between the ipsilesional PTA threshold, caloric test, and rate of abnormal EMG and recovery state. However, the initial state of ENoG, initial H-B grade, and oVEMP abnormal findings (Latency & Amplitude symmetry ratio) were significantly correlated with the rate of recovery (p = 0.025, p = 0.013, and p < 0.005, respectively).

  18. Somatosensory evoked potentials in attention deficit/hyperactivity disorder and tic disorder.

    Science.gov (United States)

    Miyazaki, Masahito; Fujii, Emiko; Saijo, Takahiko; Mori, Kenji; Kagami, Shoji

    2007-06-01

    Both attention deficit/hyperactivity disorder (ADHD) and chronic tic disorder (TD) are hyperkinetic disorders. These disorders often coexist with each other and frequently have sensory components. Therefore, we hypothesized that they might have a common pathophysiology involving the somatosensory system, especially hyper-excitabilities of primary somatosensory area. To evaluate sensory system excitability, we examined somatosensory evoked potentials (SEP) elicited by median nerve stimulation in 18 children with ADHD and 18 children with TD. Three children with ADHD and 8 children with TD showed giant SEP and the peak-to-peak amplitude for N20-P25 was also significantly greater than that obtained from normally developing children (PADHD and PADHD (PADHD and TD, its severity, especially in the left-hemisphere, differs (i.e. TD has left-ward hyper-excitability). The possibility remains that hyper-excitability of the primary somatosensory area is a reason why these disorders often coexist with each other and left-ward hyper-excitability of the primary somatosensory area is a unique feature of TD described for the first time.

  19. Do Event-Related Evoked Potentials Reflect Apathy Tendency and Motivation?

    Science.gov (United States)

    Takayoshi, Hiroyuki; Onoda, Keiichi; Yamaguchi, Shuhei

    2018-01-01

    Apathy is a mental state of diminished motivation. Although the reward system as the foundation of the motivation in the human brain has been studied extensively with neuroimaging techniques, the electrophysiological correlates of motivation and apathy have not been fully explored. Thus, in 14 healthy volunteers, we examined whether event-related evoked potentials (ERP) obtained during a simple number discrimination task with/without rewards reflected apathy tendency and a reward-dependent tendency, which were assessed separately using the apathy scale and the temperament and character inventory (TCI). Participants were asked to judge the size of a number, and received feedback based on their performance in each trial. The P3 amplitudes related to the feedback stimuli increased only in the reward condition. Furthermore, the P2 amplitudes related to the negative feedback stimuli in the reward condition had a positive correlation with the reward-dependent tendency in TCI, whereas the P3 amplitudes related to the positive feedback stimuli had a negative correlation with the apathy score. Our result suggests that the P2 and P3 ERPs to reward-related feedback stimuli are modulated in a distinctive manner by the motivational reward dependence and apathy tendency, and thus the current paradigm may be useful for investigating the brain activity associated with motivation.

  20. Preserved motor-evoked potentials but without good motor recovery in a patient with decerebrate rigidity

    Directory of Open Access Journals (Sweden)

    Chuen-Der Kao

    2011-01-01

    Full Text Available The corticospinal tract is not incriminated in decerebrate rigidity (DR. However, this has not yet been proven in humans. We applied transcranial magnetic stimulation (TMS in a decerebrate patient to support the hypothesis. A patient suffering from pontine hemorrhage with the fourth ventricular extension was admitted unconscious and in a decerebrate posture. Five days later, she regained consciousness but remained in a decerebrate posture. Motor-evoked potentials (MEPs to TMS were measured 1 week after she had regained consciousness, and this provoked muscle responses in her hands and feet bilaterally. During the follow-up, the patient’s muscle tone became persistently flaccid, although her strength increased to varying degrees in different body and limb muscles. She remained bedridden for 3 years after the stroke and could neither turn on the bed by herself nor perform skilled movements using her hands. The findings of TMS confirmed the animal studies in that the mechanism of decerebrate rigidity did not come through a damage of the corticospinal pathway. This also implies that a preserved corticospinal tract function cannot guarantee a good motor recovery in a stroke patient.

  1. [Feature Extraction of Brainstem Auditory Evoked Potential Based on Wavelet Multi-resolution Analysis].

    Science.gov (United States)

    Tian, Fuying; Sun, Ying

    2015-06-01

    We proposed a multi-resolution-wavelet-transform based method to extract brainstem auditory evoked potential (BAEP) from the background noise and then to identify its characteristics correctly. Firstly we discussed the mother wavelet and wavelet transform algorithm and proved that bi-orthogonal wavelet bior5. 5 and stationary discrete wavelet transform (SWT) were more suitable for BAEP signals. The correlation analysis of D6 scale wavelet coefficients between single trails and the ensemble average of all trails showed that the trails with good correlation (> 0. 4) had higher signal-to-noise ratio, so that we could get a clear BAEP from a few trails by an average and wavelet filter method. Finally, we used this method to select desirable trails, extracted BAEP from every 10 trails and calculated the I-V inter-waves' latency. The results showed that this strategy of trail selection was efficient. This method can not only achieve better de-noising effect, but also greatly reduce the stimulation time needed as well.

  2. Combined visual and motor evoked potentials predict multiple sclerosis disability after 20 years.

    Science.gov (United States)

    Schlaeger, Regina; Schindler, Christian; Grize, Leticia; Dellas, Sophie; Radue, Ernst W; Kappos, Ludwig; Fuhr, Peter

    2014-09-01

    The development of predictors of multiple sclerosis (MS) disability is difficult due to the complex interplay of pathophysiological and adaptive processes. The purpose of this study was to investigate whether combined evoked potential (EP)-measures allow prediction of MS disability after 20 years. We examined 28 patients with clinically definite MS according to Poser's criteria with Expanded Disability Status Scale (EDSS) scores, combined visual and motor EPs at entry (T0), 6 (T1), 12 (T2) and 24 (T3) months, and a cranial magnetic resonance imaging (MRI) scan at T0 and T2. EDSS testing was repeated at year 14 (T4) and year 20 (T5). Spearman rank correlation was used. We performed a multivariable regression analysis to examine predictive relationships of the sum of z-transformed EP latencies (s-EPT0) and other baseline variables with EDSST5. We found that s-EPT0 correlated with EDSST5 (rho=0.72, pdisability in MS. © The Author(s) 2014.

  3. Motor evoked potentials of trunk muscles in traumatic brain injury patients.

    Science.gov (United States)

    Seo, Min-Ho; Park, Sung-Hee; Ko, Myoung-Hwan; Seo, Jeong-Hwan

    2011-08-01

    To evaluate the motor innervation of trunk muscles in traumatic brain injury patients. Twenty patients (12 men and 8 women) with traumatic brain injury were enrolled in this study. Their mean age was 41 years. Motor evoked potentials (MEPs) were performed on the motor cortex. Electromyographic activities were recorded from the bilateral rectus abdominis muscles, the external oblique abdominal muscles, and the 4th and 9th thoracic erector spinae muscles. The onset latency and amplitude of contralateral and ipsilateral MEPs were measured. All patients were assessed by the Korean version of the Berg Balance Scale (K-BBS) to investigate the relationship between the frequency of MEPs in trunk muscles and gait ability. The mean frequency of ipsilateral MEPs was 23.8% with more damaged hemisphere stimulation, while the contralateral MEPs showed a mean frequency of 47.5% with more damaged hemisphere stimulation in traumatic brain injury patients. The latencies and amplitudes of MEPs obtained from the more damaged hemisphere were not significantly different from those of the less damaged hemisphere. There was no correlation between the manifestation of MEPs in trunk muscles and gait ability. The ipsilateral and contralateral corticospinal pathways to trunk muscles are less likely to be activated in traumatic brain injury patients because of direct injury of the descending corticospinal motor tract or decreased excitability of the corticospinal tract from prefrontal contusion.

  4. A MISO-ARX-Based Method for Single-Trial Evoked Potential Extraction

    Directory of Open Access Journals (Sweden)

    Nannan Yu

    2017-01-01

    Full Text Available In this paper, we propose a novel method for solving the single-trial evoked potential (EP estimation problem. In this method, the single-trial EP is considered as a complex containing many components, which may originate from different functional brain sites; these components can be distinguished according to their respective latencies and amplitudes and are extracted simultaneously by multiple-input single-output autoregressive modeling with exogenous input (MISO-ARX. The extraction process is performed in three stages: first, we use a reference EP as a template and decompose it into a set of components, which serve as subtemplates for the remaining steps. Then, a dictionary is constructed with these subtemplates, and EPs are preliminarily extracted by sparse coding in order to roughly estimate the latency of each component. Finally, the single-trial measurement is parametrically modeled by MISO-ARX while characterizing spontaneous electroencephalographic activity as an autoregression model driven by white noise and with each component of the EP modeled by autoregressive-moving-average filtering of the subtemplates. Once optimized, all components of the EP can be extracted. Compared with ARX, our method has greater tracking capabilities of specific components of the EP complex as each component is modeled individually in MISO-ARX. We provide exhaustive experimental results to show the effectiveness and feasibility of our method.

  5. Dolphin hearing during echolocation: evoked potential responses in an Atlantic bottlenose dolphin (Tursiops truncatus).

    Science.gov (United States)

    Li, Songhai; Nachtigall, Paul E; Breese, Marlee

    2011-06-15

    Auditory evoked potential (AEP) responses were recorded during echolocation in an Atlantic bottlenose dolphin (Tursiops truncatus) trained to accept suction-cup EEG electrodes and detect targets by echolocation. AEP recording was triggered by the echolocation clicks of the animal. Three targets with target strengths of -34, -28 and -22 dB were used at a target distance of 2 to 6.5 m for each target. The results demonstrated that the AEP appeared to both outgoing echolocation clicks and echoes during echolocation, with AEP complexes consisting of alternative positive and negative waves. The echo-related AEP amplitudes were obviously lower than the outgoing click-related AEP amplitudes for all the targets at the investigated target distances. However, for targets with target strengths of -22 and -28 dB, the peak-to-peak amplitudes of the echo-related AEPs were dependent on the target distances. The echo-related AEP response amplitudes increased at further target distances, demonstrating an overcompensation of echo attenuation with target distance in the echo-perception system of the dolphin biosonar. Measurement and analysis of outgoing click intensities showed that the click levels increased with target distance (R) by a factor of approximately 10 to 17.5 logR depending on target strength. The results demonstrated that a dual-component biosonar control system formed by intensity compensation behavior in both the transmission and receiving phases of a biosonar cycle exists synchronously in the dolphin biosonar system.

  6. BRAINSTEM AUDITORY EVOKED POTENTIAL AS AN INDEX OF CNS DEMYELINATION IN GUILLAIN -BARRÉ SYNDROME (GBS

    Directory of Open Access Journals (Sweden)

    Smita Singh

    2016-01-01

    Full Text Available Background: Guillain-Barré Syndrome (GBS is an acute, frequently severe and fulminant polyradicular neuropathy that is autoimmune in nature. GBS manifest as rapidly evolving areflexic motor paralysis with or without sensory disturbances. It mainly involves peripheral nervous system and autonomic nervous system. There are rare evidences about the involvement of central nervous system (CNS in GBS. Aims: The main objective of the study was to assess the CNS involvement in GBS using the Brainstem Auditory Evoked Potential (BAEP. Methods & Material: The study was conducted in the clinical neurophysiology lab in the department of physiology, CSMMU Lucknow. Study group involved 26 subjects (n=26 having GBS and control group involved 30 normal subjects (n=30. BAEPS were recorded by Neuroperfect- EMG 2000 EMG/NCV/EPsytem. The data so obtained were subjected to analysis using Statistical Package for Social Sciences (SPSS Version 13.0. Results & Conclusions: There was significant increase in PIII & PV peak latencies and PI-PIII & PI-PV interpeak latencies in both left and right ear in the study group, which showed the CNS involvement in GBS which can be assessed using BAEP.

  7. The effect of water immersion on short-latency somatosensory evoked potentials in human

    Directory of Open Access Journals (Sweden)

    Sato Daisuke

    2012-01-01

    Full Text Available Abstract Background Water immersion therapy is used to treat a variety of cardiovascular, respiratory, and orthopedic conditions. It can also benefit some neurological patients, although little is known about the effects of water immersion on neural activity, including somatosensory processing. To this end, we examined the effect of water immersion on short-latency somatosensory evoked potentials (SEPs elicited by median nerve stimuli. Short-latency SEP recordings were obtained for ten healthy male volunteers at rest in or out of water at 30°C. Recordings were obtained from nine scalp electrodes according to the 10-20 system. The right median nerve at the wrist was electrically stimulated with the stimulus duration of 0.2 ms at 3 Hz. The intensity of the stimulus was fixed at approximately three times the sensory threshold. Results Water immersion significantly reduced the amplitudes of the short-latency SEP components P25 and P45 measured from electrodes over the parietal region and the P45 measured by central region. Conclusions Water immersion reduced short-latency SEP components known to originate in several cortical areas. Attenuation of short-latency SEPs suggests that water immersion influences the cortical processing of somatosensory inputs. Modulation of cortical processing may contribute to the beneficial effects of aquatic therapy. Trial Registration UMIN-CTR (UMIN000006492

  8. Vestibular neuritis: three-dimensional videonystagmography and vestibular evoked myogenic potential results.

    Science.gov (United States)

    Chen, C W; Young, Y H; Wu, C H

    2000-10-01

    Eight patients diagnosed with vestibular neuritis received the newly developed three-dimensional videonystagmography (3D VNG) and vestibular evoked myogenic potential (VEMP) examination in order to localize the lesion site. Two (25%) of the 8 patients exhibited spontaneous nystagmus with 3 components, indicating that both the horizontal semicircular canal (HSCC) and anterior semicircular canal (ASCC) were affected. The remaining 6 patients (75%) displayed only horizontal nystagmus, meaning that only the HSCC was involved. Seven (88%) of the 8 patients had bilateral normal VEMPs, revealing sparing of the posterior semicircular canal (PSCC). In a comparative study, another seven patients with vestibular neuritis 1 year post-treatment also received the caloric test, 3D VNG and VEMP examination. Only one patient exhibited spontaneous nystagmus. An absent caloric response of the lesioned side persisted in 5 (71%) of the 7 patients. However, all patients showed normal VEMPs bilaterally. 3D VNG and VEMP examination indicates that vestibular neuritis mainly affects the superior division of the vestibular nerve, which innervates the HSCC and ASCC. Meanwhile, the function of the PSCC and saccule, innervated by the inferior vestibular nerve, is preserved.

  9. Comparative symptomatological and evoked potential studies with d-amphetamine, thioridazine, and placebo in hyperkinetic children.

    Science.gov (United States)

    Saletu, B; Saletu, M; Simeon, J; Viamontes, G; Itil, T M

    1975-06-01

    In a double-blind study, 62 hyperkinetic children were randomly assigned to 8 weeks of treatment with either placebo, thioridazine, or d-amphetamine. The overall clinical symptomatology improved with all three substances, although d-amphetamine was significantly superior to placebo and thioridazine. Out of eight symptom clusters rated by the parents, two improved significantly with placebo, one with thioridazine, and six with d-amphetamine. The d-amphetamine was superior to placebo in reducing muscular tension and superior to thioridazine in decreasing hyperactive-impulsive behavior, psychosomatic problems, and muscular tension. Out of four teachers' symptom clusters, inattentive-passive behavior was significantly improved by thioridazine (which was also superior to placebo), while hyperactivity was reduced by d-amphetamine. Quantitative evaluation of visual evoked potentials (VEPs) revealed an increase in latencies and decrease in amplitudes during thioridazine treatment. Paradoxically, d-amphetamine also increased latencies, while tending to augment amplitudes. Regression and correlation analysis of clinical symptomatology with VEP variables showed that the shorter the pretreatment latencies and the higher the amplitudes, the more disturbed was the child. Short latencies and small amplitudes in the pretreatment period were predictors of good therapeutic outcome with subsequent thioridazine treatment, while short latencies and high amplitudes were indicative of such with d-amphetamine treatment. During therapy, the greater the drug-induced augmentation of latencies, the greater the clinical improvement. Finally, VEP differences between therapy-responsive and -resistant patients were explored and discussed.

  10. A lower limb exoskeleton control system based on steady state visual evoked potentials

    Science.gov (United States)

    Kwak, No-Sang; Müller, Klaus-Robert; Lee, Seong-Whan

    2015-10-01

    Objective. We have developed an asynchronous brain-machine interface (BMI)-based lower limb exoskeleton control system based on steady-state visual evoked potentials (SSVEPs). Approach. By decoding electroencephalography signals in real-time, users are able to walk forward, turn right, turn left, sit, and stand while wearing the exoskeleton. SSVEP stimulation is implemented with a visual stimulation unit, consisting of five light emitting diodes fixed to the exoskeleton. A canonical correlation analysis (CCA) method for the extraction of frequency information associated with the SSVEP was used in combination with k-nearest neighbors. Main results. Overall, 11 healthy subjects participated in the experiment to evaluate performance. To achieve the best classification, CCA was first calibrated in an offline experiment. In the subsequent online experiment, our results exhibit accuracies of 91.3 ± 5.73%, a response time of 3.28 ± 1.82 s, an information transfer rate of 32.9 ± 9.13 bits/min, and a completion time of 1100 ± 154.92 s for the experimental parcour studied. Significance. The ability to achieve such high quality BMI control indicates that an SSVEP-based lower limb exoskeleton for gait assistance is becoming feasible.

  11. Auditory evoked potentials (AEP) methods for population-level assessment of hearing sensitivity in bottlenose dolphins

    Science.gov (United States)

    Houser, Dorian; Finneran, James

    2005-04-01

    A portable system for recording auditory evoked potentials (AEP) was developed to rapidly assess the hearing sensitivity of dolphins in air. The system utilizes a transducer embedded in a silicone suction cup to deliver amplitude modulated tones to the dolphin through the lower jaw. Frequencies tested range from 10-150 kHz and testing of both ears is completed within 90 min. AEP-determined thresholds from one subject were benchmarked against that subject's direct field behavioral audiogram to quantify variation between the two methods. To date, AEP audiograms have been obtained from over 30 bottlenose dolphins. Considerable individual variation in frequency-specific hearing sensitivity was observed. Some high-frequency hearing loss was observed in relatively young (early 20s) and old (35+ years) animals; conversely, age was not necessarily related to hearing loss as several animals greater than 40 years of age had good hearing sensitivity across the range of tested frequencies. Profound hearing loss typically occurred at higher frequencies. Decline in sensitivity was rapid in all cases and began between 50-60 kHz. Increased sample size of hearing sensitivity in dolphins suggest that the use of audiometric functions from single animals as representative of population level audiometry might be misleading.

  12. A Case of Functional (Psychogenic Monocular Hemianopia Analyzed by Measurement of Hemifield Visual Evoked Potentials

    Directory of Open Access Journals (Sweden)

    Tsuyoshi Yoneda

    2013-12-01

    Full Text Available Purpose: Functional monocular hemianopia is an extremely rare condition, for which measurement of hemifield visual evoked potentials (VEPs has not been previously described. Methods: A 14-year-old boy with functional monocular hemianopia was followed up with Goldmann perimetry and measurement of hemifield and full-field VEPs. Results: The patient had a history of monocular temporal hemianopia of the right eye following headache, nausea and ague. There was no relative afferent pupillary defect, and a color perception test was normal. Goldmann perimetry revealed a vertical monocular temporal hemianopia of the right eye; the hemianopia on the right was also detected with a binocular visual field test. Computed tomography, magnetic resonance imaging (MRI and MR angiography of the brain including the optic chiasm as well as orbital MRI revealed no abnormalities. On the basis of these results, we diagnosed the patient's condition as functional monocular hemianopia. Pattern VEPs according to the International Society for Clinical Electrophysiology of Vision (ISCEV standard were within the normal range. The hemifield pattern VEPs for the right eye showed a symmetrical latency and amplitude for nasal and temporal hemifield stimulation. One month later, the visual field defect of the patient spontaneously disappeared. Conclusions: The latency and amplitude of hemifield VEPs for a patient with functional monocular hemianopia were normal. Measurement of hemifield VEPs may thus provide an objective tool for distinguishing functional hemianopia from hemifield loss caused by an organic lesion.

  13. Modeling state entropy of the EEG and auditory evoked potentials: hypnotic and analgesic interactions.

    Science.gov (United States)

    Castro, Ana; Amorim, Pedro; Nunes, Catarina S

    2007-01-01

    Because of the complexity of raw electroencephalogram (EEG), for the anesthesiologist it is very difficult to evaluate the patient's hypnosis state. Because of this, several depth of anesthesia monitors have been developed, and are in current use at the operating room (OR). These monitors convert the information supplied by the EEG or derived signals into a simple, easy to understand index. Nowadays, general anesthesia is controlled only by the clinician, which decides what is the best drug combination for the patient, regarding all information given by monitors and sensors in the OR. In this work, we collected data from two study groups with auditory evoked potentials (AEP) monitoring, and Entropy (SE) monitoring. A model was fitted to the signals and the Hill equation parameters adjusted, in both study groups. The objective was to predict hypnosis indices, regarding only the drugs administered to a patient, and capture the initial individual patient characteristics that might influence the drugs interaction in the human body. Hypnotic and analgesic drugs interact in different ways throughout the anaesthesia stages. The models obtained captured the different dynamic interaction of drugs, during the induction and maintenance phases, demonstrating that the model must have incorporated all this information in order to perform satisfactorily. Other information like haemodynamic variables might be included in the search for the optimum model.

  14. The reproducibility of binocular pattern reversal visual evoked potentials: a single subject design.

    Science.gov (United States)

    Mellow, Tessa B; Liasis, Alki; Lyons, Ruth; Thompson, Dorothy A

    2011-06-01

    This study aimed to investigate the within-participant variability over time of both amplitude and peak latency measures of pattern reversal visual evoked potentials (pVEPs). As a large number of factors are known to contribute to the variability of the pVEPs (such as fixation instability and drowsiness), testing was conducted in controlled conditions with two co-operative participants. PVEPs were recorded during 24 sessions, over an eight-week period using the same equipment and recording settings. The participants viewed a plasma monitor binocularly from a distance of 1 meter. High contrast (97%), black and white checks of side subtense 50', 25', and 12.5' pattern reversed 3/s in a 28 degree test field. The different sized checks were presented in a pseudo-random order. Three runs, each of 100 trials, were acquired to each stimulus from an active electrode placed at Oz referred to aFz. The amplitude of N80-P100 and the latency of P100 were measured. P100 amplitude and latency were stable across sessions and did not depend upon the order of check size presentation. As expected, variation in amplitude was greater than peak latency. The coefficients of variation for different check sizes and participants were 9-14% for pVEP amplitude, but only 1-2% for P100 latency.

  15. Test-retest reliability of infant event related potentials evoked by faces.

    Science.gov (United States)

    Munsters, N M; van Ravenswaaij, H; van den Boomen, C; Kemner, C

    2017-04-05

    Reliable measures are required to draw meaningful conclusions regarding developmental changes in longitudinal studies. Little is known, however, about the test-retest reliability of face-sensitive event related potentials (ERPs), a frequently used neural measure in infants. The aim of the current study is to investigate the test-retest reliability of ERPs typically evoked by faces in 9-10 month-old infants. The infants (N=31) were presented with neutral, fearful and happy faces that contained only the lower or higher spatial frequency information. They were tested twice within two weeks. The present results show that the test-retest reliability of the face-sensitive ERP components is moderate (P400 and Nc) to substantial (N290). However, there is low test-retest reliability for the effects of the specific experimental manipulations (i.e. emotion and spatial frequency) on the face-sensitive ERPs. To conclude, in infants the face-sensitive ERP components (i.e. N290, P400 and Nc) show adequate test-retest reliability, but not the effects of emotion and spatial frequency on these ERP components. We propose that further research focuses on investigating elements that might increase the test-retest reliability, as adequate test-retest reliability is necessary to draw meaningful conclusions on individual developmental trajectories of the face-sensitive ERPs in infants. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  16. Diffusion tensor imaging of the inferior colliculus and brainstem auditory-evoked potentials in preterm infants

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    Reiman, Milla; Lehtonen, Liisa; Lapinleimu, Helena [Turku University Central Hospital, Department of Paediatrics, Turku (Finland); Parkkola, Riitta [Turku University Central Hospital, Department of Radiology and Turku PET Centre, Turku (Finland); Johansson, Reijo [Turku University Central Hospital, Department of Otorhinolaryngology, Turku (Finland); Jaeaeskelaeinen, Satu K. [Turku University Central Hospital, Department of Clinical Neurophysiology, Turku (Finland); Kujari, Harry [Turku University Central Hospital, Department of Pathology, Turku (Finland); Haataja, Leena [Turku University Central Hospital, Department of Paediatric Neurology, Turku (Finland)

    2009-08-15

    Preterm and low-birth-weight infants have an increased risk of sensorineural hearing loss. Brainstem auditory-evoked potentials (BAEP) are an effective method to detect subtle deficits in impulse conduction in the auditory pathway. Abnormalities on diffusion tensor imaging (DTI) have been shown to be associated with perinatal white-matter injury and reduced fractional anisotropy (FA) has been reported in patients with sensorineural hearing loss. To evaluate the possibility of a correlation between BAEP and DTI of the inferior colliculus in preterm infants. DTI at term age and BAEP measurements were performed on all very-low-birth-weight or very preterm study infants (n=56). FA and apparent diffusion coefficient (ADC) of the inferior colliculus were measured from the DTI. Shorter BAEP wave I, III, and V latencies and I-III and I-V intervals and higher wave V amplitude correlated with higher FA of the inferior colliculus. The association between the DTI findings of the inferior colliculus and BAEP responses suggests that DTI can be used to assess the integrity of the auditory pathway in preterm infants. (orig.)

  17. Abnormal recovery function of somatosensory evoked potentials in patients with primary insomnia.

    Science.gov (United States)

    Huang, Zhaoyang; Zhan, Shuqin; Li, Ning; Ding, Yan; Wang, Yuping

    2012-08-15

    Neurobiological correlates underlying insomnia are poorly understood. The hyperarousal of the central nervous system indicates that cortical excitability may be abnormal in patients with insomnia. The purpose of the present study was to investigate changes in cortical excitability by examining the recovery function of median nerve somatosensory evoked potentials (SEPs) in patients with primary insomia (PI). We studied the recovery function of median nerve SEPs in 12 medication-naive PI patients and in 12 age- and sex-matched healthy subjects. SEPs in response to single stimulus and paired stimuli at interstimulus intervals (ISIs) of 20, 60, 100 and 150 ms were recorded. The recovery function of the cortical components of frontal P20 and parietal N20 showed significantly reduced suppression in PI patients as compared to healthy controls. In conclusion, this is the first study investigating changes in cortical excitability in PI patients by examining the recovery function of median nerve SEPs. The present study suggests that cortical excitability is increased in PI patients. Dysfunction of inhibitory GABAergic interneurons of the cerebral cortex might contribute to the increased cortical excitability in PI patients. Copyright © 2012 Elsevier Ltd. All rights reserved.

  18. Improving vestibular evoked myogenic potential reliability by using a blood pressure manometer.

    Science.gov (United States)

    Vanspauwen, Robby; Wuyts, Floris L; Van de Heyning, Paul H

    2006-01-01

    To improve the reliability of vestibular evoked myogenic potentials (VEMP), we propose a feedback method making use of a readily available blood pressure manometer with inflatable cuff to control the sternocleidomastoid muscle (SCM) contraction. Prospective study. The feedback method for SCM contraction consisted of subjects pushing with their jaw against the hand-held inflated cuff to generate a specified cuff pressure. This pressure level was monitored by subject and investigator. First, we tested in a group of healthy subjects whether there was a learning or fatigue effect during four successive SCM contraction runs when making use of the feedback method. Then, we investigated the mean rectified voltage (MRV) values of the SCM. Next, we examined the hypothesis that the MRV values of the SCM contraction measured before and simultaneously with the VEMP test were equal when using this feedback method. Finally, we compared the VEMP amplitude variability in two circumstances: with and without the feedback method. There was no learning or fatigue effect, and the MRV values measured before the VEMP were not significantly different from those measured during the VEMP test. The VEMP amplitude variability was significantly lower when applying the feedback method than when no feedback method was used. This feedback method improves significantly the VEMP amplitude reliability.

  19. Pattern evoked cortical potential topography and positron emission computed tomography in cases with homonymous quadrantanopsia

    International Nuclear Information System (INIS)

    Kakisu, Yonetsugu; Adachi-Usami, Emiko; Kuroda, Noriko; Kawamura, Mitsuru; Yamazaki, Toshiro.

    1985-01-01

    Pattern evoked cortical potentials (PVECPs) and positron emission computed tomography (PET) were studied in two cases with lower homonymous quadrantanopsia caused by occlusion or hemorrhages of the artery of the optic radiation. Using 15 O 2 and C 15 O 2 as a tracer, PET was performed at rest under opened eye stimulation on 6 cm and 8 cm transverse section above the orbito-meatal line. On OM-6 level where the visual cortex of right and left hemisphere received the upper visual field information, symmetrical images of 15 O 2 and C 15 O 2 uptake were found. However, they were lateralized at the non-affected hemisphere in the images of OM-8 level, which corresponded to the anatomical lesion. The PVECP topogram recorded to the stimulation of the right and left lower quadrant visual field was studied by a 16 channel recording system. The positive maxima at the peak latency of P100 were found only at the non-affected hemisphere. It was, thus, proved that PVECP topogram and PET findings could demonstrate the functional abnormalities of the visual cortex in accordance with visual field defect measured by subjective perimetry. (author)

  20. Noninvasive scalp recording of cortical auditory evoked potentials in the alert macaque monkey.

    Science.gov (United States)

    Itoh, Kosuke; Nejime, Masafumi; Konoike, Naho; Nakada, Tsutomu; Nakamura, Katsuki

    2015-09-01

    Scalp-recorded evoked potentials (EP) provide researchers and clinicians with irreplaceable means for recording stimulus-related neural activities in the human brain, due to its high temporal resolution, handiness, and, perhaps more importantly, non-invasiveness. This work recorded the scalp cortical auditory EP (CAEP) in unanesthetized monkeys by using methods that are essentially identical to those applied to humans. Young adult rhesus monkeys (Macaca mulatta, 5-7 years old) were seated in a monkey chair, and their head movements were partially restricted by polystyrene blocks and tension poles placed around their head. Individual electrodes were fixated on their scalp using collodion according to the 10-20 system. Pure tone stimuli were presented while electroencephalograms were recorded from up to nineteen channels, including an electrooculogram channel. In all monkeys (n = 3), the recorded CAEP comprised a series of positive and negative deflections, labeled here as macaque P1 (mP1), macaque N1 (mN1), macaque P2 (mP2), and macaque N2 (mN2), and these transient responses to sound onset were followed by a sustained potential that continued for the duration of the sound, labeled the macaque sustained potential (mSP). mP1, mN2 and mSP were the prominent responses, and they had maximal amplitudes over frontal/central midline electrode sites, consistent with generators in auditory cortices. The study represents the first noninvasive scalp recording of CAEP in alert rhesus monkeys, to our knowledge. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Profiles in fibromyalgia: algometry, auditory evoked potentials and clinical characterization of different subtypes.

    Science.gov (United States)

    Triñanes, Yolanda; González-Villar, Alberto; Gómez-Perretta, Claudio; Carrillo-de-la-Peña, María T

    2014-11-01

    The heterogeneity found in fibromyalgia (FM) patients has led to the investigation of disease subgroups, mainly based on clinical features. The aim of this study was to test the hypothesis that clinical FM subgroups are associated with different underlying pathophysiological mechanisms. Sixty-three FM patients were classified in type I or type II, according to the Fibromyalgia Impact Questionnaire (FIQ), and in mild/moderate versus severe FM, according to the severity of three cardinal symptoms considered in the American College of Rheumatology (ACR) 2010 criteria (unrefreshed sleep, cognitive problems and fatigue). To validate the subgroups obtained by these two classifications, we calculated the area under the receiver operating characteristic curves for various clinical variables and for two potential biomarkers of FM: Response to experimental pressure pain (algometry) and the amplitude/intensity slopes of the auditory evoked potentials (AEPs) obtained to stimuli of increasing intensity. The variables that best discriminated type I versus type II were those related to depression, while the indices of clinical or experimental pain (threshold or tolerance) did not significantly differ between them. The variables that best discriminated the mild/moderate versus severe subgroups were those related to the algometry. The AEPs did not allow discrimination among the generated subsets. The FIQ-based classification allows the identification of subgroups that differ in psychological distress, while the index based on the ACR 2010 criteria seems to be useful to characterize the severity of FM mainly based on hyperalgesia. The incorporation of potential biomarkers to generate or validate classification criteria is crucial to advance in the knowledge of FM and in the understanding of pathophysiological pathways.

  2. Current source density analysis of the potential evoked in hippocampus by perirhinal cortex stimulation.

    Science.gov (United States)

    Liu, P; Bilkey, D K

    1997-01-01

    Previous anatomical research has demonstrated that the perirhinal cortex (PRC) projects to the dorsal hippocampal CA1 field. We have recently presented data (Liu and Bilkey, Hippocampus 1996; 6:125-135) which suggests that this pathway courses via the lateral perforant path (LPP). In the present study, laminar profiles of the average evoked potentials and current source density (CSD) analysis were used to study the input from the perirhinal cortex to the dorsal hippocampus in the urethane-anaesthetized rat. Stimulation of the lateral perforant path activated a current sink in the stratum lacunosum-moleculare of CA1 and the outer molecular layer of the dentate gyrus with an onset latency of 3.5 ms. Stimulation of the perirhinal cortex produced a very similar sink-source pattern with an onset latency of 4.0 ms. Higher-intensity stimulation of lateral entorhinal cortex also produced a similar pattern with an onset latency of 4.5 ms. Electrolytic lesions of PRC conducted 4-5 days prior to testing resulted in a major decrease (58%) in the amplitude of the LPP-elicited potentials and a corresponding reduction across the whole source-sink pattern. A similar result was observed following ibotenic acid lesions of PRC. In contrast, similar-sized electrolytic lesions of lateral entorhinal cortex produced a much smaller (16%) decrease in potential amplitude and little change in the source-sink pattern. These data provide further support for the hypothesis that perirhinal cortex projects to both the dentate gyrus and CA1 regions of the hippocampus via the lateral perforant path.

  3. The Effectiveness of FES-Evoked EMG Potentials to Assess Muscle Force and Fatigue in Individuals with Spinal Cord Injury

    Directory of Open Access Journals (Sweden)

    Morufu Olusola Ibitoye

    2014-07-01

    Full Text Available The evoked electromyographic signal (eEMG potential is the standard index used to monitor both electrical changes within the motor unit during muscular activity and the electrical patterns during evoked contraction. However, technical and physiological limitations often preclude the acquisition and analysis of the signal especially during functional electrical stimulation (FES-evoked contractions. Hence, an accurate quantification of the relationship between the eEMG potential and FES-evoked muscle response remains elusive and continues to attract the attention of researchers due to its potential application in the fields of biomechanics, muscle physiology, and rehabilitation science. We conducted a systematic review to examine the effectiveness of eEMG potentials to assess muscle force and fatigue, particularly as a biofeedback descriptor of FES-evoked contractions in individuals with spinal cord injury. At the outset, 2867 citations were identified and, finally, fifty-nine trials met the inclusion criteria. Four hypotheses were proposed and evaluated to inform this review. The results showed that eEMG is effective at quantifying muscle force and fatigue during isometric contraction, but may not be effective during dynamic contractions including cycling and stepping. Positive correlation of up to r = 0.90 (p < 0.05 between the decline in the peak-to-peak amplitude of the eEMG and the decline in the force output during fatiguing isometric contractions has been reported. In the available prediction models, the performance index of the eEMG signal to estimate the generated muscle force ranged from 3.8% to 34% for 18 s to 70 s ahead of the actual muscle force generation. The strength and inherent limitations of the eEMG signal to assess muscle force and fatigue were evident from our findings with implications in clinical management of spinal cord injury (SCI population.

  4. The effectiveness of FES-evoked EMG potentials to assess muscle force and fatigue in individuals with spinal cord injury.

    Science.gov (United States)

    Ibitoye, Morufu Olusola; Estigoni, Eduardo H; Hamzaid, Nur Azah; Wahab, Ahmad Khairi Abdul; Davis, Glen M

    2014-07-14

    The evoked electromyographic signal (eEMG) potential is the standard index used to monitor both electrical changes within the motor unit during muscular activity and the electrical patterns during evoked contraction. However, technical and physiological limitations often preclude the acquisition and analysis of the signal especially during functional electrical stimulation (FES)-evoked contractions. Hence, an accurate quantification of the relationship between the eEMG potential and FES-evoked muscle response remains elusive and continues to attract the attention of researchers due to its potential application in the fields of biomechanics, muscle physiology, and rehabilitation science. We conducted a systematic review to examine the effectiveness of eEMG potentials to assess muscle force and fatigue, particularly as a biofeedback descriptor of FES-evoked contractions in individuals with spinal cord injury. At the outset, 2867 citations were identified and, finally, fifty-nine trials met the inclusion criteria. Four hypotheses were proposed and evaluated to inform this review. The results showed that eEMG is effective at quantifying muscle force and fatigue during isometric contraction, but may not be effective during dynamic contractions including cycling and stepping. Positive correlation of up to r = 0.90 (p peak-to-peak amplitude of the eEMG and the decline in the force output during fatiguing isometric contractions has been reported. In the available prediction models, the performance index of the eEMG signal to estimate the generated muscle force ranged from 3.8% to 34% for 18 s to 70 s ahead of the actual muscle force generation. The strength and inherent limitations of the eEMG signal to assess muscle force and fatigue were evident from our findings with implications in clinical management of spinal cord injury (SCI) population.

  5. [Recognition of the spatially transformed objects in men and women: an analysis of the behavior and evoked potentials].

    Science.gov (United States)

    Slavutskaia, A V; Gerasimenko, N Iu; Mikhaĭlova, E S

    2012-01-01

    In 16 men and 15 women analyzed the accuracy, reaction time and visual evoked potentials during the recognition of familiar objects at different levels of spatial transformation. We used the three levels of transformation: in a fixed position relative to each other details were carried out (1) the displacement of all the details in the radial direction and (2 and 3) a similar shift in conjunction with the rotation of all the details of the figure by +/- 0-45 and +/- 45-90 degrees. The task performance was not dependent on gender: the transformation of the image led to a deterioration of identification with the most identification impairment in the case of maximal details' rotation. Changes in evoked potentials (ERP) are different for men and women. Only in men early (100 ms after stimulus) response of the parietal cortex associated with the level of figure transformation: the more rotation evoked the higher the response. In women figure transformation evoked the ERP changes in the time window of negativity N170, they are associated with figure ungrouping but not with details rotation, and are localized in other visual areas--occipital and temporal. The data obtained are discussed in light of theory of gender specificity of the visual representations of space.

  6. Action potentials: to the nucleus and beyond.

    Science.gov (United States)

    Saha, Ramendra N; Dudek, Serena M

    2008-04-01

    The neuronal nucleus is now widely accepted as playing a vital role in maintaining long-term changes in synaptic effectiveness. To act, however, the nucleus must be appropriately relayed with information regarding the latest round of synaptic plasticity. Several constraints of doing so in a neuron pertain to the often significant spatial distance of synapses from the nucleus and the number of synapses required for such a signal to reach functional levels in the nucleus. Largely based on the sensitivity of transcriptional responses to NMDA receptor antagonists, it has been postulated that the signals are physically relayed by biochemical messengers from the synapse to the nucleus. Alternatively, a second, less often considered but equally viable method of signal transduction may be initiated by action potentials generated proximal to the nucleus, wherefrom the signal can be relayed directly by calcium or indirectly by biochemical second messengers. We consider action potential-dependent signaling to the nucleus to have its own computational advantages over the synapse-to-nucleus signal for some functions. This minireview summarizes the logic and experimental support for these two modes of signaling and attempts to validate the action potential model as playing an important role in transcriptional regulation relating specifically to long-term synaptic plasticity.

  7. Serial recording of median nerve stimulated subcortical somatosensory evoked potentials (SEPs) in developing brain death.

    Science.gov (United States)

    Buchner, H; Ferbert, A; Hacke, W

    1988-01-01

    Subcortical somatosensory evoked potentials (SEPs) to median nerve stimulation were recorded serially in 35 patients during the evolution towards brain death and in brain death. Neuropathological alterations of the central nervous system down to the C1/C2 spinal cord segment in brain death are well known. SEP components supposed to be generated above this level should be lost in brain death, while components generated below should not be altered. Erb's point, scalp and neck potentials were recorded at C3/4, or over the spinous process C7, using an Fz reference. In 10 patients additional montages, including spinous process C2-Fz, a non-cephalic reference (Fz-contralateral shoulder) and a posterior to anterior neck montage (spinous process C7-jugulum) were used. The cephalic referenced N9 and N11 peaks remained unchanged until brain death. N9 and N11 decreased in parallel in amplitude and increased in latency after systemic effects like hypoxia or hypothermia occurred. The cephalic referenced 'N14' decreased in amplitude and increased in latency after the clinical brain death syndrome was observed, while N13 in the posterior to anterior neck montage remained unchanged. The alteration of 'N14' went parallel to the decrease of the P14 amplitude. The subcortical SEPs in the cephalic referenced lead are supposed to be a peak composed by a horizontally orientated dorsal horn generated N13 and a rostrally orientated P14 arising at the level of the foramen magnum. The deterioration of the non-cephalic referenced P14 and of its cephalic referenced reflection 'N14' seems to provide an additional objective criterion for the diagnosis of brain death.

  8. Brain potentials evoked by intraepidermal electrical stimuli reflect the central sensitization of nociceptive pathways.

    Science.gov (United States)

    Liang, M; Lee, M C; O'Neill, J; Dickenson, A H; Iannetti, G D

    2016-08-01

    Central sensitization (CS), the increased sensitivity of the central nervous system to somatosensory inputs, accounts for secondary hyperalgesia, a typical sign of several painful clinical conditions. Brain potentials elicited by mechanical punctate stimulation using flat-tip probes can provide neural correlates of CS, but their signal-to-noise ratio is limited by poor synchronization of the afferent nociceptive input. Additionally, mechanical punctate stimulation does not activate nociceptors exclusively. In contrast, low-intensity intraepidermal electrical stimulation (IES) allows selective activation of type II Aδ-mechano-heat nociceptors (II-AMHs) and elicits reproducible brain potentials. However, it is unclear whether hyperalgesia from IES occurs and coexists with secondary mechanical punctate hyperalgesia, and whether the magnitude of the electroencephalographic (EEG) responses evoked by IES within the hyperalgesic area is increased. To address these questions, we explored the modulation of the psychophysical and EEG responses to IES by intraepidermal injection of capsaicin in healthy human subjects. We obtained three main results. First, the intensity of the sensation elicited by IES was significantly increased in participants who developed robust mechanical punctate hyperalgesia after capsaicin injection (i.e., responders), indicating that hyperalgesia from IES coexists with punctate mechanical hyperalgesia. Second, the N2 peak magnitude of the EEG responses elicited by IES was significantly increased after the intraepidermal injection of capsaicin in responders only. Third, a receiver-operator characteristics analysis showed that the N2 peak amplitude is clearly predictive of the presence of CS. These findings suggest that the EEG responses elicited by IES reflect secondary hyperalgesia and therefore represent an objective correlate of CS. Copyright © 2016 the American Physiological Society.

  9. Using visual evoked potentials for the early detection of amnestic mild cognitive impairment: a pilot investigation.

    Science.gov (United States)

    Fix, Spencer T; Arruda, James E; Andrasik, Frank; Beach, Jameson; Groom, Kevin

    2015-01-01

    Amnesic mild cognitive impairment (MCIa) is often characterized as an early stage of Alzheimer's dementia (AD). The latency of the P2, an electroencephalographic component of the flash visual evoked potential (FVEP), is significantly longer in those with AD or MCIa when compared with controls. The present investigation examined the diagnostic accuracy of several FVEP-P2 procedures in distinguishing people with MCIa and controls. The latency of the FVEP-P2 was measured in participants exposed to a single flash condition and five double flash conditions. The double flash conditions had different inter-stimulus intervals between the pair of strobe flashes. Significant group differences were observed in the single flash and two of the double flash conditions. One of the double flash conditions (100 ms) displayed a higher predictive accuracy than the single flash condition, suggesting that this novel procedure may have more diagnostic potential. Participants with MCIa displayed similar P2 latencies across conditions, while controls exhibited a consistent pattern of P2 latency differences. These differences demonstrate that the double stimulation procedure resulted in a measurable refractory effect for controls but not for those with MCIa. The pattern of P2 group differences suggests that those with MCIa have compromised cholinergic functioning that results in impaired visual processing. Results from the present investigation lend support to the theory that holds MCIa as an intermediate stage between normal healthy aging and the neuropathology present in AD. Measuring the FVEP-P2 during several double stimulation conditions could provide diagnostically useful information about the health of the cholinergic system. Copyright © 2014 John Wiley & Sons, Ltd.

  10. Characterizing the time course of an implicature: an evoked potentials study.

    Science.gov (United States)

    Noveck, Ira A; Posada, Andres

    2003-05-01

    This work employs Evoked Potential techniques as 19 participants are confronted with sentences that have the potential to produce scalar implicatures, like in Some elephants have trunks. Such an Underinformative utterance is of interest to pragmatists because it can be considered to have two different truth values. It can be considered true when taken at face value but false if one were to treat Some with the implicature Not All. Two accounts of implicature production are compared. The neo-Gricean approach (e.g., Levinson, 2000) assumes that implicatures intrude automatically on the semantics of a term like Some. Relevance Theory (Sperber & Wilson, 1985/1996) assumes that implicatures are effortful and not automatic. In this experiment, the participants are presented with 25 Underinformative sentences along with 25 sentences that are Patently True (e.g. Some houses have bricks) and 25 that are Patently False (e.g. Some crows have radios). As reported in an earlier study (Noveck, 2001), Underinformative sentences prompt strong individual differences. Seven participants here responded true to all (or nearly all) of the Underinformative sentences and the remaining 12 responded false to all (or nearly all) of them. The present study showed that those who responded false to the Underinformative sentences took significantly longer to do so that those who responded true. The ERP data indicate that: (a) the Patently True and Patently False sentences prompt steeper N400's--indicating greater semantic integration--than the Underinformative sentences and that (b) regardless of one's ultimate response to the Underinformative sentences, the N400's were remarkably flat, indicating no particular reaction to these sentences. Collectively, the data are taken to show that implicatures are part of a late-arriving, effort-demanding decision process.

  11. A Comparison of Visual Evoked Potential (VEP)-Based Methods for the Low-Cost Emotiv EPOC Neuroheadset

    OpenAIRE

    Hvaring, Fredrik Tron; Ulltveit-Moe, Andreas H

    2014-01-01

    Brain computer interfaces (BCIs) enable interaction with computers through electrical brain signals recorded from the scalp through an electroencephalogram (EEG). These BCIs are characterized by expensive equipment and long setup times, which limits their commercial use. In this thesis, a BCI was implemented that uses the low-cost EEG acquisition device Emotiv EPOC and visual evoked potentials (VEPs), which are potentials in the EEG elicited by visual stimulus. A structured literature review ...

  12. Action potential generation in the small intestine of W mutant mice that lack interstitial cells of Cajal

    DEFF Research Database (Denmark)

    Malysz, J; Thuneberg, L; Mikkelsen, Hanne Birte

    1996-01-01

    + channel blockade evoked the typical spikelike action potentials. Electron microscopy identified few methylene blue-positive cells in the W/Wv small intestine associated with Auerbach's plexus as individual ICC. Numbers of resident macrophage-like cells (MLC) and fibroblast-like cells (FLC) were...

  13. Abnormalities in auditory evoked potentials of 75 patients with Arnold-Chiari malformations types I and II.

    Science.gov (United States)

    Henriques Filho, Paulo Sergio A; Pratesi, Riccardo

    2006-09-01

    To evaluate the frequency and degree of severity of abnormalities in the auditory pathways in patients with Chiari malformations type I and II. This is a series-of-case descriptive study in which the possible presence of auditory pathways abnormalities in 75 patients (48 children and 27 adults) with Chiari malformation types I and II were analyzed by means of auditory evoked potentials evaluation. The analysis was based on the determination of intervals among potentials peak values, absolute latency and amplitude ratio among potentials V and I. Among the 75 patients studied, 27 (36%) disclosed Arnold-Chiari malformations type I and 48 (64%) showed Arnold-Chiari malformations type II. Fifty-three (71%) of these patients showed some degree of auditory evoked potential abnormalities. Tests were normal in the remaining 22 (29%) patients. Auditory evoked potentials testing can be considered a valuable instrument for diagnosis and evaluation of brain stem functional abnormalities in patients with Arnold-Chiari malformations type I and II. The determination of the presence and degree of severity of these abnormalities can be contributory to the prevention of further handicaps in these patients either through physical therapy or by means of precocious corrective surgical intervention.

  14. Steady state visual evoked potential (SSVEP based brain-computer interface (BCI performance under different perturbations.

    Directory of Open Access Journals (Sweden)

    Zafer İşcan

    Full Text Available Brain-computer interface (BCI paradigms are usually tested when environmental and biological artifacts are intentionally avoided. In this study, we deliberately introduced different perturbations in order to test the robustness of a steady state visual evoked potential (SSVEP based BCI. Specifically we investigated to what extent a drop in performance is related to the degraded quality of EEG signals or rather due to increased cognitive load. In the online tasks, subjects focused on one of the four circles and gave feedback on the correctness of the classification under four conditions randomized across subjects: Control (no perturbation, Speaking (counting loudly and repeatedly from one to ten, Thinking (mentally counting repeatedly from one to ten, and Listening (listening to verbal counting from one to ten. Decision tree, Naïve Bayes and K-Nearest Neighbor classifiers were used to evaluate the classification performance using features generated by canonical correlation analysis. During the online condition, Speaking and Thinking decreased moderately the mean classification accuracy compared to Control condition whereas there was no significant difference between Listening and Control conditions across subjects. The performances were sensitive to the classification method and to the perturbation conditions. We have not observed significant artifacts in EEG during perturbations in the frequency range of interest except in theta band. Therefore we concluded that the drop in the performance is likely to have a cognitive origin. During the Listening condition relative alpha power in a broad area including central and temporal regions primarily over the left hemisphere correlated negatively with the performance thus most likely indicating active suppression of the distracting presentation of the playback. This is the first study that systematically evaluates the effects of natural artifacts (i.e. mental, verbal and audio perturbations on SSVEP

  15. Steady state visual evoked potential (SSVEP) based brain-computer interface (BCI) performance under different perturbations.

    Science.gov (United States)

    İşcan, Zafer; Nikulin, Vadim V

    2018-01-01

    Brain-computer interface (BCI) paradigms are usually tested when environmental and biological artifacts are intentionally avoided. In this study, we deliberately introduced different perturbations in order to test the robustness of a steady state visual evoked potential (SSVEP) based BCI. Specifically we investigated to what extent a drop in performance is related to the degraded quality of EEG signals or rather due to increased cognitive load. In the online tasks, subjects focused on one of the four circles and gave feedback on the correctness of the classification under four conditions randomized across subjects: Control (no perturbation), Speaking (counting loudly and repeatedly from one to ten), Thinking (mentally counting repeatedly from one to ten), and Listening (listening to verbal counting from one to ten). Decision tree, Naïve Bayes and K-Nearest Neighbor classifiers were used to evaluate the classification performance using features generated by canonical correlation analysis. During the online condition, Speaking and Thinking decreased moderately the mean classification accuracy compared to Control condition whereas there was no significant difference between Listening and Control conditions across subjects. The performances were sensitive to the classification method and to the perturbation conditions. We have not observed significant artifacts in EEG during perturbations in the frequency range of interest except in theta band. Therefore we concluded that the drop in the performance is likely to have a cognitive origin. During the Listening condition relative alpha power in a broad area including central and temporal regions primarily over the left hemisphere correlated negatively with the performance thus most likely indicating active suppression of the distracting presentation of the playback. This is the first study that systematically evaluates the effects of natural artifacts (i.e. mental, verbal and audio perturbations) on SSVEP-based BCIs. The

  16. Effects of multiple sclerosis brainstem lesions on sound lateralization and brainstem auditory evoked potentials.

    Science.gov (United States)

    Levine, R A; Gardner, J C; Fullerton, B C; Stufflebeam, S M; Carlisle, E W; Furst, M; Rosen, B R; Kiang, N Y

    1993-06-01

    Magnetic resonance (MR) imaging, brainstem auditory evoked potentials (BAEPs), and tests of interaural time and level discrimination were performed on sixteen subjects with multiple sclerosis (MS). Objective criteria were used to define MR lesions. Of the eleven subjects in whom no pontine lesions were detected and the one subject who had pontine lesions that did not encroach upon the auditory pathways, all had normal BAEPs and interaural level discrimination, although a few had abnormal interaural time discrimination. Of four subjects with lesions involving the pontine auditory pathway, all had both abnormal BAEPs and abnormal interaural time discrimination; one also had abnormal interaural level discrimination. Analysis of the data suggest the following: waves I and II are generated peripheral to the middle of the ventral acoustic stria (VAS); wave III is generated ipsilaterally in the region of the rostral VAS, caudal superior olivary complex (SOC) and trapezoid body (TB); and waves V and L are generated contralaterally, rostral to the SOC-TB. The region of the ipsilateral rostral SOC-TB is implicated as part of the pathway involved in the generation of waves V and L. Interaural time discrimination of both high and low frequency stimuli were affected by all brainstem lesions that encroached on auditory pathways. A unilateral lesion in the region of the LL affected interaural time discrimination for low-frequency stimuli less severely than bilateral lesions of the LL or a unilateral lesion of the VAS. The only interaural level discrimination abnormality occurred for a subject with a unilateral lesion involving the entire rostral VAS. It appears that detailed analysis of lesion locations coupled with electrophysiological and psychophysical data holds promise for testing hypotheses concerning the function of various human auditory brainstem structures.

  17. Extracting visual evoked potentials from EEG data recorded during fMRI-guided transcranial magnetic stimulation.

    Science.gov (United States)

    Sadeh, Boaz; Yovel, Galit

    2014-05-12

    Transcranial Magnetic Stimulation (TMS) is an effective method for establishing a causal link between a cortical area and cognitive/neurophysiological effects. Specifically, by creating a transient interference with the normal activity of a target region and measuring changes in an electrophysiological signal, we can establish a causal link between the stimulated brain area or network and the electrophysiological signal that we record. If target brain areas are functionally defined with prior fMRI scan, TMS could be used to link the fMRI activations with evoked potentials recorded. However, conducting such experiments presents significant technical challenges given the high amplitude artifacts introduced into the EEG signal by the magnetic pulse, and the difficulty to successfully target areas that were functionally defined by fMRI. Here we describe a methodology for combining these three common tools: TMS, EEG, and fMRI. We explain how to guide the stimulator's coil to the desired target area using anatomical or functional MRI data, how to record EEG during concurrent TMS, how to design an ERP study suitable for EEG-TMS combination and how to extract reliable ERP from the recorded data. We will provide representative results from a previously published study, in which fMRI-guided TMS was used concurrently with EEG to show that the face-selective N1 and the body-selective N1 component of the ERP are associated with distinct neural networks in extrastriate cortex. This method allows us to combine the high spatial resolution of fMRI with the high temporal resolution of TMS and EEG and therefore obtain a comprehensive understanding of the neural basis of various cognitive processes.

  18. Evoked potentials in large-scale cortical networks elicited by TMS of the visual cortex

    Science.gov (United States)

    Grossman, Emily D.; Srinivasan, Ramesh

    2011-01-01

    Single pulses of transcranial magnetic stimulation (TMS) result in distal and long-lasting oscillations, a finding directly challenging the virtual lesion hypothesis. Previous research supporting this finding has primarily come from stimulation of the motor cortex. We have used single-pulse TMS with simultaneous EEG to target seven brain regions, six of which belong to the visual system [left and right primary visual area V1, motion-sensitive human middle temporal cortex, and a ventral temporal region], as determined with functional MRI-guided neuronavigation, and a vertex “control” site to measure the network effects of the TMS pulse. We found the TMS-evoked potential (TMS-EP) over visual cortex consists mostly of site-dependent theta- and alphaband oscillations. These site-dependent oscillations extended beyond the stimulation site to functionally connected cortical regions and correspond to time windows where the EEG responses maximally diverge (40, 200, and 385 ms). Correlations revealed two site-independent oscillations ∼350 ms after the TMS pulse: a theta-band oscillation carried by the frontal cortex, and an alpha-band oscillation over parietal and frontal cortical regions. A manipulation of stimulation intensity at one stimulation site (right hemisphere V1-V3) revealed sensitivity to the stimulation intensity at different regions of cortex, evidence of intensity tuning in regions distal to the site of stimulation. Together these results suggest that a TMS pulse applied to the visual cortex has a complex effect on brain function, engaging multiple brain networks functionally connected to the visual system with both invariant and site-specific spatiotemporal dynamics. With this characterization of TMS, we propose an alternative to the virtual lesion hypothesis. Rather than a technique that simulates lesions, we propose TMS generates natural brain signals and engages functional networks. PMID:21715670

  19. Early clinical and subclinical visual evoked potential and Humphrey's visual field defects in cryptococcal meningitis.

    Directory of Open Access Journals (Sweden)

    Anand Moodley

    Full Text Available Cryptococcal induced visual loss is a devastating complication in survivors of cryptococcal meningitis (CM. Early detection is paramount in prevention and treatment. Subclinical optic nerve dysfunction in CM has not hitherto been investigated by electrophysiological means. We undertook a prospective study on 90 HIV sero-positive patients with culture confirmed CM. Seventy-four patients underwent visual evoked potential (VEP testing and 47 patients underwent Humphrey's visual field (HVF testing. Decreased best corrected visual acuity (BCVA was detected in 46.5% of patients. VEP was abnormal in 51/74 (68.9% right eyes and 50/74 (67.6% left eyes. VEP P100 latency was the main abnormality with mean latency values of 118.9 (±16.5 ms and 119.8 (±15.7 ms for the right and left eyes respectively, mildly prolonged when compared to our laboratory references of 104 (±10 ms (p<0.001. Subclinical VEP abnormality was detected in 56.5% of normal eyes and constituted mostly latency abnormality. VEP amplitude was also significantly reduced in this cohort but minimally so in the visually unimpaired. HVF was abnormal in 36/47 (76.6% right eyes and 32/45 (71.1% left eyes. The predominant field defect was peripheral constriction with an enlarged blind spot suggesting the greater impact by raised intracranial pressure over that of optic neuritis. Whether this was due to papilloedema or a compartment syndrome is open to further investigation. Subclinical HVF abnormalities were minimal and therefore a poor screening test for early optic nerve dysfunction. However, early optic nerve dysfunction can be detected by testing of VEP P100 latency, which may precede the onset of visual loss in CM.

  20. Enhanced speech perception in noise and cortical auditory evoked potentials in professional musicians.

    Science.gov (United States)

    Meha-Bettison, Kiriana; Sharma, Mridula; Ibrahim, Ronny K; Mandikal Vasuki, Pragati Rao

    2018-01-01

    The current research investigated whether professional musicians outperformed non-musicians on auditory processing and speech-in-noise perception as assessed using behavioural and electrophysiological tasks. Spectro-temporal processing skills were assessed using a psychoacoustic test battery. Speech-in-noise perception was measured using the Listening in Spatialised Noise - Sentences (LiSN-S) test and Cortical Auditory Evoked Potentials (CAEPs) recorded to the speech syllable/da/presented in quiet and in 8-talker babble noise at 0, 5, and 10 dB signal-to-noise ratios (SNRs). Ten professional musicians and 10 non-musicians participated in this study. Musicians significantly outperformed non-musicians in the frequency discrimination task and low-cue condition of the LiSN-S test. Musicians' N1 amplitude showed no difference between 5 dB and 0 dB SNR conditions while non-musicians showed significantly lower N1 amplitude at 0 dB SNR compared to 5 dB SNR. Brain-behaviour correlation for musicians showed a significant association between CAEPs at 5 dB SNR and the low-cue condition of the LiSN-S test at 30-70 ms. Time-frequency analysis indicated musicians had significantly higher alpha power desynchronisation in the 0 dB SNR condition indicating involvement of attention. Through the use of behavioural and electrophysiological data, the results provide converging evidence for improved speech recognition in noise in musicians.

  1. Prandial states modify the reactivity of the gustatory cortex using gustatory evoked potentials in humans

    Directory of Open Access Journals (Sweden)

    Agnès eJACQUIN-PIQUES

    2016-01-01

    Full Text Available Previous functional Magnetic Resonance Imaging studies evaluated the role of satiety on cortical taste area activity and highlighted decreased activation in the orbito-frontal cortex when food was eaten until satiation. The modulation of orbito-frontal neurons (secondary taste area by ad libitum food intake has been associated with the pleasantness of the food’s flavor. The insula and frontal operculum (primary taste area are also involved in reward processing. The aim was to compare human gustatory evoked potentials (GEP recorded in the primary and secondary gustatory cortices in a fasted state with those after food intake. Fifteen healthy volunteers were enrolled in this observational study. In each of two sessions, two GEP recordings were performed (at 11:00 am and 1:30 pm in response to sucrose gustatory stimulation, and a sucrose-gustatory threshold was determined. During one session, a standard lunch was provided between the two GEP recordings. During the other session, subjects had nothing to eat. Hunger sensation, wanting, liking and the perception of the solution’s intensity were evaluated with visual analogue scales. GEP latencies measured in the Pz (p<0.001, Cz (p<0.01, Fz (p<0.001 recordings (primary taste area were longer after lunch than in the pre-prandial condition. Fp1 and Fp2 latencies (secondary taste area tended to be longer after lunch, but the difference was not significant. No difference was observed for the sucrose-gustatory threshold regardless of the session and time. Modifications in the primary taste area activity during the post-prandial period occurred regardless of the nature of the food eaten and could represent the activity of the frontal operculum and insula, which was recently shown to be modulated by gut signals (GLP-1, CCK, ghrelin, or insulin through vagal afferent neurons or metabolic changes of the internal milieu after nutrient absorption. This trial was registered at clinicalstrials.gov as NCT

  2. Stimulation artifact correction method for estimation of early cortico-cortical evoked potentials.

    Science.gov (United States)

    Trebaul, Lena; Rudrauf, David; Job, Anne-Sophie; Mălîia, Mihai Dragos; Popa, Irina; Barborica, Andrei; Minotti, Lorella; Mîndruţă, Ioana; Kahane, Philippe; David, Olivier

    2016-05-01

    Effective connectivity can be explored using direct electrical stimulations in patients suffering from drug-resistant focal epilepsies and investigated with intracranial electrodes. Responses to brief electrical pulses mimic the physiological propagation of signals and manifest as cortico-cortical evoked potentials (CCEP). The first CCEP component is believed to reflect direct connectivity with the stimulated region but the stimulation artifact, a sharp deflection occurring during a few milliseconds, frequently contaminates it. In order to recover the characteristics of early CCEP responses, we developed an artifact correction method based on electrical modeling of the electrode-tissue interface. The biophysically motivated artifact templates are then regressed out of the recorded data as in any classical template-matching removal artifact methods. Our approach is able to make the distinction between the physiological responses time-locked to the stimulation pulses and the non-physiological component. We tested the correction on simulated CCEP data in order to quantify its efficiency for different stimulation and recording parameters. We demonstrated the efficiency of the new correction method on simulations of single trial recordings for early responses contaminated with the stimulation artifact. The results highlight the importance of sampling frequency for an accurate analysis of CCEP. We then applied the approach to experimental data. The model-based template removal was compared to a correction based on the subtraction of the averaged artifact. This new correction method of stimulation artifact will enable investigators to better analyze early CCEP components and infer direct effective connectivity in future CCEP studies. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  3. Diagnostic Value of Facial Nerve Antidromic Evoked Potential in Patients With Bell's Palsy: A Preliminary Study

    Science.gov (United States)

    Lee, Ji Hoon; Kim, Sun Mi; Yang, Hea Eun; Lee, Jang Woo

    2014-01-01

    Objective To assess the practical diagnostic value of facial nerve antidromic evoked potential (FNAEP), we compared it with the diagnostic value of the electroneurography (ENoG) test in Bell's palsy. Methods In total, 20 patients with unilateral Bell's palsy were recruited. Between the 1st and 17th days after the onset of facial palsy, FNAEP and ENoG tests were conducted. The degeneration ratio and FNAEP latency difference between the affected and unaffected sides were calculated in all subjects. Results In all patients, FNAEP showed prolonged latencies on the affected side versus the unaffected side. The difference was statistically significant. In contrast, there was no significant difference between sides in the normal control group. In 8 of 20 patients, ENoG revealed a degeneration ratio less than 50%, but FNAEP show a difference of more than 0.295±0.599 ms, the average value of normal control group. This shows FNAEP could be a more sensitive test for Bell's palsy diagnosis than ENoG. In particular, in 10 patients tested within 7 days after onset, an abnormal ENoG finding was noted in only four of them, but FNAEP showed a significant latency difference in all patients at this early stage. Thus, FANEP was more sensitive in detecting facial nerve injury than the ENoG test (p=0.031). Conclusion FNAEP has some clinical value in the diagnosis of facial nerve degeneration. It is important that FNAEP be considered in patients with facial palsy at an early stage and integrated with other relevant tests. PMID:25024963

  4. Detection of multiple sclerosis with visual evoked potentials--an unsupervised computational intelligence system.

    Science.gov (United States)

    Dasey, T J; Micheli-Tzanakou, E

    2000-09-01

    This paper describes the application of a novel unsupervised pattern recognition system to the classification of the Visual Evoked Potentials (VEP's) of normal and multiple sclerosis (MS) patients. The method combines a traditional statistical feature extractor with a fuzzy clustering method, all implemented in a parallel neural network architecture. The optimization routine, ALOPEX, is used to train the network while decreasing the likelihood of local solutions. The unsupervised system includes a feature extraction and clustering module, trained by the optimization routine ALOPEX. Through maximization of the output variance of each node, and an architecture which excludes redundancy, the feature extraction network retains the most significant Karhunen-Loeve expansion vectors. The clustering module uses a modification to the Fuzzy c-Means (FCM) clustering algorithms, where ALOPEX adjusts a set of cluster centers to minimize an objective error function. The result combines the power of the FCM algorithms with the advantage of a more global solution from ALOPEX. The new pattern recognition system is used to cluster the VEP's of 13 normal and 12 MS subjects. The classification with this technique can, without supervision, separate the patient population into two groups which largely correspond to the MS and control subject groups. A suitable threshold can be chosen so that the recognizer chooses no false negatives. The use of multiple stimulation patterns appears to improve the reliability of the decision. The reasoning of most neural networks in their decision making cannot easily be extracted upon the completion of training. However, due to the linearity of the network nodes, the cluster prototypes of this unsupervised system can be reconstructed to illustrate the reasoning of the system. In this application, this analysis hints at the usefulness of previously unused portions of the VEP in detecting MS. It also indicates a possible use of the system as a training

  5. Short latency vestibular evoked potentials in the Japanese quail (Coturnix coturnix japonica)

    Science.gov (United States)

    Jones, S. M.; Jones, T. A.; Shukla, R.

    1997-01-01

    Short-latency vestibular-evoked potentials to pulsed linear acceleration were characterized in the quail. Responses occurred within 8 ms following the onset of stimuli and were composed of a series of positive and negative peaks. The latencies and amplitudes of the first four peaks were quantitatively characterized. Mean latencies at 1.0 g ms-1 ranged from 1265 +/- 208 microseconds (P1, N = 18) to 4802 +/- 441 microseconds (N4, N = 13). Amplitudes ranged from 3.72 +/- 1.51 microV (P1/N1, N = 18) to 1.49 +/- 0.77 microV (P3/N3, N = 16). Latency-intensity (LI) slopes ranged from -38.7 +/- 7.3 microseconds dB-1 (P1, N = 18) to -71.6 +/- 21.9 microseconds dB-1 (N3, N = 15) and amplitude-intensity (AI) slopes ranged from 0.20 +/- 0.08 microV dB-1 (P1/N1, N = 18) to 0.07 +/- 0.04 microV dB-1 (P3/N3, N = 11). The mean response threshold across all animals was -21.83 +/- 3.34 dB re: 1.0 g ms-1 (N = 18). Responses remained after cochlear extirpation showing that they could not depend critically on cochlear activity. Responses were eliminated by destruction of the vestibular end organs, thus showing that responses depended critically and specifically on the vestibular system. The results demonstrate that the responses are vestibular and the findings provide a scientific basis for using vestibular responses to evaluate vestibular function through ontogeny and senescence in the quail.

  6. Predictive patterns of sensory evoked potentials in comatose brain injured patients evolving to brain death.

    Science.gov (United States)

    Scarpino, Maenia; Lanzo, Giovanni; Carrai, Riccardo; Lolli, Francesco; Migliaccio, Maria Luisa; Spalletti, Maddalena; Peris, Adriano; Amantini, Aldo; Grippo, Antonello

    2017-02-01

    To assess whether Somatosensory Evoked Potentials (SEPs), recorded within 24h after ICU admission, are reliable predictors of brain death (BD) in comatose patients with acquired brain injury of various aetiologies. SEPs were classified as absent (A), pathological (P), and normal (N). Considering SEP recordings from both hemispheres, 6 patterns were identified: NN, NP, PP, NA, AP, and AA. The final endpoint was BD. Of the 203 patients included in the study, 70 (34%) evolved toward BD. The survival analysis indicated that the combination of SEP patterns in a two-graded scale (grade 1: NN-NP-PP-NA, and grade 2: AP-AA), allowed for prediction of BD with the best accuracy. This aggregation predicted BD with a sensitivity of 75.7% (CI: 64-84), a specificity of 76.6% (CI: 68-83), a positive predictive value of 64.2% (CI: 53-74) and a negative predictive value of 84.3% (CI: 77-90) in overall patients, and with a sensitivity of 75.0% (CI: 63-84), a specificity of 84.9% (CI: 75-90), a positive predictive value of 77.5% (CI: 63-88) and a negative predictive value of 84.3% (CI: 74-91) when excluding cardiac arrest. It is worth including SEPs, in association with other investigations and clinical signs, in prognostic scores of BD. The early identification of patients at high risk of evolving towards BD could help physicians to optimise management. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  7. Nicotinic modulation of auditory evoked potential electroencephalography in a rodent neurodevelopmental model of schizophrenia.

    Science.gov (United States)

    Kohlhaas, Kathy L; Robb, Holly M; Roderwald, Victoria A; Rueter, Lynne E

    2015-10-15

    Schizophrenia is a chronic disease that has been hypothesized to be linked to neurodevelopmental abnormalities. Schizophrenia patients exhibit impairments in basic sensory processing including sensory gating deficits in P50 and mismatch negativity (MMN). Neuronal nicotinic acetylcholine receptor (nAChR) agonists have been reported to attenuate these deficits. Gestational exposure of rats to methylazoxymethanol acetate (MAM) at embryonic day 17 leads to developmental disruption of the limbic-cortical system. MAM exposed offspring show neuropathological and behavioral changes that have similarities with those seen in schizophrenia. In this study, we aimed to assess whether N40 auditory sensory gating (the rodent form of P50 gating) and MMN deficits as measures of auditory evoked potential (AEP) electroencephalography (EEG) are present in MAM rats and whether nAChR agonists could attend the deficit. E17 male MAM and sham rats were implanted with cortical electrodes at 2 months of age. EEG recordings evaluating N40 gating and MMN paradigms were done comparing effects of vehicle (saline), nicotine and the α7 agonist ABT-107. Deficits were seen for MAM rats compared to sham animals in both N40 auditory sensory gating and MMN AEP recordings. There was a strong trend for N40 deficits to be attenuated by both nicotine (0.16mg/kg i.p. base) and ABT-107 (1.0mg/kg i.p. base). MMN deficits were significantly attenuated by ABT-107 but not by nicotine. These data support the MAM model as a useful tool for translating pharmacodynamic effects in clinical medicine studies of novel therapeutic treatments for schizophrenia. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Fractal Dimension Analysis of Transient Visual Evoked Potentials: Optimisation and Applications.

    Science.gov (United States)

    Boon, Mei Ying; Henry, Bruce Ian; Chu, Byoung Sun; Basahi, Nour; Suttle, Catherine May; Luu, Chi; Leung, Harry; Hing, Stephen

    2016-01-01

    The visual evoked potential (VEP) provides a time series signal response to an external visual stimulus at the location of the visual cortex. The major VEP signal components, peak latency and amplitude, may be affected by disease processes. Additionally, the VEP contains fine detailed and non-periodic structure, of presently unclear relevance to normal function, which may be quantified using the fractal dimension. The purpose of this study is to provide a systematic investigation of the key parameters in the measurement of the fractal dimension of VEPs, to develop an optimal analysis protocol for application. VEP time series were mathematically transformed using delay time, τ, and embedding dimension, m, parameters. The fractal dimension of the transformed data was obtained from a scaling analysis based on straight line fits to the numbers of pairs of points with separation less than r versus log(r) in the transformed space. Optimal τ, m, and scaling analysis were obtained by comparing the consistency of results using different sampling frequencies. The optimised method was then piloted on samples of normal and abnormal VEPs. Consistent fractal dimension estimates were obtained using τ = 4 ms, designating the fractal dimension = D2 of the time series based on embedding dimension m = 7 (for 3606 Hz and 5000 Hz), m = 6 (for 1803 Hz) and m = 5 (for 1000Hz), and estimating D2 for each embedding dimension as the steepest slope of the linear scaling region in the plot of log(C(r)) vs log(r) provided the scaling region occurred within the middle third of the plot. Piloting revealed that fractal dimensions were higher from the sampled abnormal than normal achromatic VEPs in adults (p = 0.02). Variances of fractal dimension were higher from the abnormal than normal chromatic VEPs in children (p = 0.01). A useful analysis protocol to assess the fractal dimension of transformed VEPs has been developed.

  9. Clinical utility and limitations of intraoperative monitoring of visual evoked potentials.

    Science.gov (United States)

    Luo, Yeda; Regli, Luca; Bozinov, Oliver; Sarnthein, Johannes

    2015-01-01

    During surgeries that put the visual pathway at risk of injury, continuous monitoring of the visual function is desirable. However, the intraoperative monitoring of the visual evoked potential (VEP) is not yet widely used. We evaluate here the clinical utility of intraoperative VEP monitoring. We analyzed retrospectively 46 consecutive surgeries in 2011-2013. High luminance stimulating devices delivered flash stimuli on the closed eyelid during intravenous anesthesia. We monitored VEP features N75 and P100 and took patients' preoperative and postoperative visual function from patient charts. Postoperative ophthalmologic workup was performed in 25 (54%) patients and preoperatively in 28 (61%) patients. VEP recordings were feasible in 62 of 85 eyes (73%) in 46 patients. All 23 eyes without VEP had impaired vision. During surgery, VEPs remained stable throughout surgery in 50 eyes. In 44 of these, visual function did not deteriorate and three patients (6 eyes) developed hemianopia. VEP decreased transiently in 10 eyes and visual function of all was preserved. VEPs were lost permanently in 2 eyes in two patients without new postoperative visual impairment. Satisfactory intraoperative VEP monitoring was feasible in all patients except in those with severe visual impairment. Preservation of VEPs predicted preserved visual function. During resection of lesions in the visual cortex, VEP monitoring could not detect new major visual field defects due to injury in the posterior visual pathway. Intraoperative VEPs were sensitive enough to detect vascular damage during aneurysm clipping and mechanical manipulation of the anterior visual pathway in an early reversible stage. Intraoperative VEP monitoring influenced surgical decisions in selected patients and proved to be a useful supplement to the toolbox of intraoperative neurophysiological monitoring.

  10. Clinical utility and limitations of intraoperative monitoring of visual evoked potentials.

    Directory of Open Access Journals (Sweden)

    Yeda Luo

    Full Text Available During surgeries that put the visual pathway at risk of injury, continuous monitoring of the visual function is desirable. However, the intraoperative monitoring of the visual evoked potential (VEP is not yet widely used. We evaluate here the clinical utility of intraoperative VEP monitoring.We analyzed retrospectively 46 consecutive surgeries in 2011-2013. High luminance stimulating devices delivered flash stimuli on the closed eyelid during intravenous anesthesia. We monitored VEP features N75 and P100 and took patients' preoperative and postoperative visual function from patient charts. Postoperative ophthalmologic workup was performed in 25 (54% patients and preoperatively in 28 (61% patients.VEP recordings were feasible in 62 of 85 eyes (73% in 46 patients. All 23 eyes without VEP had impaired vision. During surgery, VEPs remained stable throughout surgery in 50 eyes. In 44 of these, visual function did not deteriorate and three patients (6 eyes developed hemianopia. VEP decreased transiently in 10 eyes and visual function of all was preserved. VEPs were lost permanently in 2 eyes in two patients without new postoperative visual impairment.Satisfactory intraoperative VEP monitoring was feasible in all patients except in those with severe visual impairment. Preservation of VEPs predicted preserved visual function. During resection of lesions in the visual cortex, VEP monitoring could not detect new major visual field defects due to injury in the posterior visual pathway. Intraoperative VEPs were sensitive enough to detect vascular damage during aneurysm clipping and mechanical manipulation of the anterior visual pathway in an early reversible stage. Intraoperative VEP monitoring influenced surgical decisions in selected patients and proved to be a useful supplement to the toolbox of intraoperative neurophysiological monitoring.

  11. Long-latency TMS-evoked potentials during motor execution and inhibition

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    Kentaro eYamanaka

    2013-11-01

    Full Text Available Transcranial magnetic stimulation (TMS has often been used in conjunction with electroencephalography (EEG, which is effective for the direct demonstration of cortical reactivity and corticocortical connectivity during cognitive tasks through the spatio-temporal pattern of long-latency TMS-evoked potentials (TEPs. However, it remains unclear what pattern is associated with the inhibition of a planned motor response. Therefore, we performed TMS-EEG recording during a go/stop task, in which participants were instructed to click a computer mouse with a right index finger when an indicator that was moving with a constant velocity reached a target (go trial or to avoid the click when the indicator randomly stopped just before it reached the target (stop trial. Single-pulse TMS to the left (contralateral or right (ipsilateral motor cortex was applied 500 ms before or just at the target time. TEPs related to motor execution and inhibition were obtained by subtractions between averaged EEG waveforms with and without TMS. As a result, in TEPs induced by both contralateral and ipsilateral TMS, small oscillations were followed by a prominent negative deflection around the TMS site peaking at approximately 100 ms post-TMS (N100, and a less pronounced later positive component (LPC over the broad areas that was centered at the midline-central site in both go and stop trials. However, compared to the pattern in go and stop trials with TMS at 500 ms before the target time, N100 and LPC were differently modulated in the go and stop trials with TMS just at the target time. The amplitudes of both N100 and LPC decreased in go trials, while the amplitude of LPC decreased and the latency of LPC was delayed in both go and stop trials. These results suggested that TMS-induced neuronal reactions in the motor cortex and subsequent their propagation to surrounding cortical areas might change functionally according to task demand when executing and inhibiting a motor

  12. Saccular function in otosclerosis patients: bone conducted-vestibular evoked myogenic potential analysis.

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    Amin Amali

    2014-02-01

    Full Text Available Vestibular involvements have long been observed in otosclerotic patients. Among vestibular structures saccule has the closest anatomical proximity to the sclerotic foci, so it is the most prone vestibular structure to be affected during the otosclerosis process. The aim of this study was to investigate the saccular function in patients suffering from otosclerosis, by means of Vestibular Evoked Myogenic Potential (VEMP. The material consisted of 30 otosclerosis patients and 20 control subjects. All participants underwent audiometric and VEMP testing. Analysis of tests results revealed that the mean values of Air-Conducted Pure Tone Average (AC-PTA and Bone-Conducted Pure Tone Average (BC-PTA in patients were 45.28 ± 15.57 and 19.68 ± 10.91, respectively and calculated 4 frequencies Air Bone Gap (ABG was 25.64 ± 9.95. The VEMP response was absent in 14 (28.57% otosclerotic ears. A statistically significant increase in latency of the p13 was found in the affected ears (P=0.004, differences in n23 latency did not reach a statistically significant level (P=0.112. Disparities in amplitude of p13-n23 in between two study groups was statistically meaningful (P=0.009, indicating that the patients with otosclerosis had lower amplitudes. This study tends to suggest that due to the direct biotoxic effect of the materials released from the otosclerosis foci on saccular receptors, there might be a possibility of vestibular dysfunction in otosclerotic patients.

  13. Test-retest reliability of binaural simultaneous cervical vestibular evoked myogenic potential recording.

    Science.gov (United States)

    Lee, Min Young; Yi, Yeo-Jeen; Park, Hanaro; Kim, Mi Hee; Lee, Jun Ho; Oh, Seung-Ha; Suh, Myung-Whan

    2015-01-01

    The purpose of this study is to compare the test-retest reliability of cervical vestibular evoked myogenic potential (cVEMP) parameters between monaural sequential (mSEQ) cVEMP and binaural simultaneous (bSIM) cVEMP recordings. Twenty two volunteers aged 22 from 38 years were enrolled. Two different methods of cVEMP measurement were performed in the subjects. The two methods were (1) monaural sequential (mSEQ) measurement and (2) binaural simultaneous (bSIM) measurement. After a mean test-retest interval of 7.1 ± 2.8 days, the second run of the cVEMP measurement was performed in a random order. To compare the test-retest reliability of mSEQ and bSIM cVEMP responses, Intraclass correlation coefficient (ICC) and Spearman correlation were applied. Both p13 and n23 latencies did not show a statistically significant difference between the two cVEMP recording methods. Also, there were no significant differences in the inter-peak amplitude (IPA) and interaural amplitude difference (IAD) ratio between the two methods. The test-retest reliability of inter-peak amplitude (IPA) demonstrated a positive correlation for both mSEQ and bSIM cVEMP methods. The IAD ratio of bSIM cVEMP response demonstrated a statistically significant test-retest reliability (ICC = 0.691, p= 0.015). However, the IAD ratio of mSEQ cVEMP response did not demonstrate a statistically significant test-retest correlation. Results implicate that bSIM cVEMP not only saves time, but it also has an advantage of a more reliable test-retest outcome.

  14. Diagnostic Value of Somatosensory-Evoked Potential Monitoring During Cerebral Aneurysm Clipping: A Systematic Review.

    Science.gov (United States)

    Thirumala, Parthasarathy D; Udesh, Reshmi; Muralidharan, Aditya; Thiagarajan, Karthy; Crammond, Donald J; Chang, Yue-Fang; Balzer, Jeffrey R

    2016-05-01

    Perioperative stroke is a known complication in patients undergoing surgical clipping of cerebral aneurysms. To evaluate whether intraoperative changes in somatosensory-evoked potential (SSEP) monitoring during cerebral aneurysm clipping is diagnostic of perioperative stroke. An electronic search of PubMed, Embase, and Web of Science databases was done for studies published through May 2015 on SSEP monitoring in cerebral aneurysm clipping for predicting postoperative outcomes. All titles and abstracts were screened independently on the basis of predetermined criteria. Inclusion criteria included randomized clinical trials and prospective or retrospective cohort reviews; patients with intracranial aneurysms who underwent surgical clipping with intra-operative SSEP monitoring and postoperative neurologic assessment; studies published in English on adult humans ≥18 years with sample size of ≥50; and studies inclusive of an abstract with adequate details on outcomes. A total of 14 articles with a sample population of 2015 patients were analyzed. SSEP monitoring demonstrated a strong mean specificity of 84.5% (95% confidence interval [95% CI] -76.3 to 90.3) but weaker sensitivity of 56.8% (95% CI 44.1-68.6) for predicting stroke. A diagnostic odds ratio of 7.772 (95% CI 5.133-11.767) suggested that the odds of observing an SSEP change among those with a postoperative neurologic deficit were 7 times greater than those without a neurologic deficit. Intraoperative SSEP monitoring is highly specific for predicting neurologic outcome after cerebral aneurysm clipping. Patients with postoperative neurologic deficits are 7 times more likely to have had intraoperative SSEP changes. SSEP monitoring may help design prevention strategies to reduce stroke rates after cerebral aneurysm clipping. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Evaluation of brain stem auditory evoked potentials in stable patients with chronic obstructive pulmonary disease

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    Gupta Prem

    2008-01-01

    Full Text Available Though there are few studies addressing brainstem auditory evoked potentials (BAEP in patients with chronic obstructive pulmonary disease (COPD, subclinical BAEP abnormalities in stable COPD patients have not been studied. The present study aimed to evaluate the BAEP abnormalities in this study group. Materials and Methods : In the present study, 80 male subjects were included: COPD group comprised 40 smokers with stable COPD with no clinical neuropathy; 40 age-matched healthy volunteers served as the control group. Latencies of BAEP waves I, II, III, IV, and V, together with interpeak latencies (IPLs of I-III, I-V, and III-V, and amplitudes of waves I-Ia and V-Va were studied in both the groups to compare the BAEP abnormalities in COPD group; the latter were correlated with patient characteristics and Mini-Mental Status Examination Questionnaire (MMSEQ scores to seek any significant correlation. Results: Twenty-six (65% of the 40 COPD patients had BAEP abnormalities. We observed significantly prolonged latencies of waves I, III, V over left ear and waves III, IV, V over right ear; increased IPLs of I-V, III-V over left ear and of I-III, I-V, III-V over right side. Amplitudes of waves I-Ia and V-Va were decreased bilaterally. Over left ear, the latencies of wave I and III were significantly correlated with FEV 1 ; and amplitude of wave I-Ia, with smoking pack years. A weak positive correlation between amplitude of wave I-Ia and duration of illness; and a weak negative correlation between amplitude of wave V-Va and MMSEQ scores were seen over right side. Conclusions : We observed significant subclinical BAEP abnormalities on electrophysiological evaluation in studied stable COPD male patients having mild-to-moderate airflow obstruction.

  16. Multifocal visual evoked potential in optic neuritis, ischemic optic neuropathy and compressive optic neuropathy

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    Manju Jayaraman

    2014-01-01

    Full Text Available Purpose: To investigate the effect of optic neuritis (ON, ischemic optic neuropathy (ION and compressive optic neuropathy (CON on multifocal visual evoked potential (mfVEP amplitudes and latencies, and to compare the parameters among three optic nerve disorders. Materials and Methods: mfVEP was recorded for 71 eyes of controls and 48 eyes of optic nerve disorders with subgroups of optic neuritis (ON, n = 21 eyes, ischemic optic neuropathy (ION, n = 14 eyes, and compressive optic neuropathy (CON, n = 13 eyes. The size of defect in mfVEP amplitude probability plots and relative latency plots were analyzed. The pattern of the defect in amplitude probability plot was classified according to the visual field profile of optic neuritis treatment trail (ONTT. Results: Median of mfVEP amplitude (log SNR averaged across 60 sectors were reduced in ON (0.17 (0.13-0.33, ION (0.14 (0.12-0.21 and CON (0.21 (0.14-0.30 when compared to controls. The median mfVEP relative latencies compared to controls were significantly prolonged in ON and CON group of 10.53 (2.62-15.50 ms and 5.73 (2.67-14.14 ms respectively compared to ION group (2.06 (-4.09-13.02. The common mfVEP amplitude defects observed in probability plots were diffuse pattern in ON, inferior altitudinal defect in ION and temporal hemianopia in CON eyes. Conclusions: Optic nerve disorders cause reduction in mfVEP amplitudes. The extent of delayed latency noted in ischemic optic neuropathy was significantly lesser compared to subjects with optic neuritis and compressive optic neuropathy. mfVEP amplitudes can be used to objectively assess the topography of the visual field defect.

  17. Can bispectral index or auditory evoked potential index predict implicit memory during propofol-induced sedation?

    Science.gov (United States)

    Wang, Yun; Yue, Yun; Sun, Yong-hai; Wu, An-shi

    2006-06-05

    Some patients still suffer from implicit memory of intraoperative events under adequate depth of anaesthesia. The elimination of implicit memory should be a necessary aim of clinical general anaesthesia. However, implicit memory cannot be tested during anaesthesia yet. We propose bispectral index (BIS) and auditory evoked potential index (AEPI), as predictors of implicit memory during anaesthesia. Thirty-six patients were equally divided into 3 groups according to the Observer's Assessment of Alertness/Sedation Score: A, level 3; B, level 2; and C, level 1. Every patient was given the first auditory stimulus before sedation. Then every patient received the second auditory stimulus after the target level of sedation had been reached. BIS and AEPI were monitored before and after the second auditory stimulus presentation. Four hours later, the inclusion test and exclusion test were performed on the ward using process dissociation procedure and the scores of implicit memory estimated. In groups A and B but not C, implicit memory estimates were statistically greater than zero (P memory scores in group A did not differ significantly from those in group B (P > 0.05). Implicit memory scores correlated with BIS and AEPI (P AEPI. The 95% cutoff points of BIS and AEPI for predicting implicit memory are 47 and 28, respectively. Implicit memory does not disappear until the depth of sedation increases to level 1 of OAA/S score. Implicit memory scores correlate well with BIS and AEPI during sedation. BIS is a better index for predicting implicit memory than AEPI during propofol induced sedation.

  18. Objective measures of binaural masking level differences and comodulation masking release based on late auditory evoked potentials

    DEFF Research Database (Denmark)

    Epp, Bastian; Yasin, Ifat; Verhey, Jesko L.

    2013-01-01

    The audibility of important sounds is often hampered due to the presence of other masking sounds. The present study investigates if a correlate of the audibility of a tone masked by noise is found in late auditory evoked potentials measured from human listeners. The audibility of the target sound...... in a masking release (i: binaural masking level difference; ii: comodulation masking release) compared to a condition where those cues are not present. Late auditory evoked potentials (N1, P2) were recorded for the stimuli at a constant masker level, but different signal levels within the same set of listeners...... who participated in the psychoacoustical experiment. The data indicate differences in N1 and P2 between stimuli with and without interaural phase disparities. However, differences for stimuli with and without coherent masker modulation were only found for P2, i.e., only P2 is sensitive to the increase...

  19. Evaluation of Somatosensory Evoked Potential and Pain Rating Index in a Patient with Spinal Cord Injury Accepted Cell Therapy.

    Science.gov (United States)

    Hua, Rongrong; Li, Ping; Wang, Xiaodong; Yang, Jing; Zheng, Pei; Niu, Xinxin; Li, Yan; An, Yihua

    2016-05-01

    Spinal cord injury (SCI) causes a high incidence of motor and sensory dysfunctions accompanied with neuropathic pain. No effective treatment is available. Both somatosensory evoked potential (SSEP) and neuropathic pain (NPP) are transmitted via myelinated large diameter fibers of deep sensory pathways. Here we aimed to evaluate whether SSEP can consistently and objectively assess transmission of deep sensory pathways, and to examine the effects of umbilical cord mesenchymal stem cell (UCMSC) transplantation on SSEP and NPP as assessed by the pain rating index (PRI) in a patient with a 2-year history of complete cervical SCI. We demonstrate that SSEP can directly reflect physiological function of myelinated large fibers in deep sensory pathway transmission (NPP is also transmitted by the same pathway). One year after UCMSC transplantation, the SSEP parameter, PRI, and clinical presentations of NPP significantly improved. Spinal cord, neuropathic pain, somatosensory evoked potential, umbilical cord mesenchymal stem cells.

  20. Climbing fiber-evoked endocannabinoid signaling heterosynaptically suppresses presynaptic cerebellar long-term potentiation

    NARCIS (Netherlands)

    B.J. van Beugen (Boeke); R.Y. Nagaraja (Raghavendra); C.R.W. Hansel (Christian)

    2006-01-01

    textabstractEndocannabinoid signaling has been demonstrated to mediate depolarization-induced suppression of excitation at climbing fiber (CF) and parallel fiber (PF) synapses onto cerebellar Purkinje cells. Here, we show that CF-evoked release of cannabinoids (CBs) additionally suppresses a

  1. Light scattering changes follow evoked potentials from hippocampal Schaeffer collateral stimulation

    DEFF Research Database (Denmark)

    Rector, D M; Poe, G R; Kristensen, Morten Pilgaard

    1997-01-01

    We assessed relationships of evoked electrical and light scattering changes from cat dorsal hippocampus following Schaeffer collateral stimulation. Under anesthesia, eight stimulating electrodes were placed in the left hippocampal CA field and an optic probe, coupled to a photodiode or a charge...

  2. Facilitation of soleus but not tibialis anterior motor evoked potentials before onset of antagonist contraction

    DEFF Research Database (Denmark)

    Geertsen, Svend Sparre; Zuur, Abraham Theodore; Nielsen, Jens Bo

    2008-01-01

    the MEP is evoked. Methods: Seated subjects (n=11) were instructed to react to an auditory cue by contracting either the tibialis anterior (TA) or soleus muscle of the left ankle to 30% of their maximal dorsiflexion voluntary contraction (MVC) or plantar flexion MVC, respectively. Focal TMS at 1.2 x motor...

  3. Steady-state pattern electroretinogram and short-duration transient visual evoked potentials in glaucomatous and healthy eyes.

    Science.gov (United States)

    Amarasekera, Dilru C; Resende, Arthur F; Waisbourd, Michael; Puri, Sanjeev; Moster, Marlene R; Hark, Lisa A; Katz, L Jay; Fudemberg, Scott J; Mantravadi, Anand V

    2018-01-01

    This study evaluates two rapid electrophysiological glaucoma diagnostic tests that may add a functional perspective to glaucoma diagnosis. This study aimed to determine the ability of two office-based electrophysiological diagnostic tests, steady-state pattern electroretinogram and short-duration transient visual evoked potentials, to discern between glaucomatous and healthy eyes. This is a cross-sectional study in a hospital setting. Forty-one patients with glaucoma and 41 healthy volunteers participated in the study. Steady-state pattern electroretinogram and short-duration transient visual evoked potential testing was conducted in glaucomatous and healthy eyes. A 64-bar-size stimulus with both a low-contrast and high-contrast setting was used to compare steady-state pattern electroretinogram parameters in both groups. A low-contrast and high-contrast checkerboard stimulus was used to measure short-duration transient visual evoked potential parameters in both groups. Steady-state pattern electroretinogram parameters compared were MagnitudeD, MagnitudeD/Magnitude ratio, and the signal-to-noise ratio. Short-duration transient visual evoked potential parameters compared were amplitude and latency. MagnitudeD was significantly lower in glaucoma patients when using a low-contrast (P = 0.001) and high-contrast (P state pattern electroretinogram stimulus. MagnitudeD/Magnitude ratio and SNR were significantly lower in the glaucoma group when using a high-contrast 64-bar-size stimulus (P state pattern electroretinogram was effectively able to discern between glaucomatous and healthy eyes. Steady-state pattern electroretinogram may thus have a role as a clinically useful electrophysiological diagnostic tool. © 2017 Royal Australian and New Zealand College of Ophthalmologists.

  4. Cortical Auditory Evoked Potentials with Simple (Tone Burst) and Complex (Speech) Stimuli in Children with Cochlear Implant.

    Science.gov (United States)

    Martins, Kelly Vasconcelos Chaves; Gil, Daniela

    2017-10-01

    Introduction  The registry of the component P1 of the cortical auditory evoked potential has been widely used to analyze the behavior of auditory pathways in response to cochlear implant stimulation. Objective  To determine the influence of aural rehabilitation in the parameters of latency and amplitude of the P1 cortical auditory evoked potential component elicited by simple auditory stimuli (tone burst) and complex stimuli (speech) in children with cochlear implants. Method  The study included six individuals of both genders aged 5 to 10 years old who have been cochlear implant users for at least 12 months, and who attended auditory rehabilitation with an aural rehabilitation therapy approach. Participants were submitted to research of the cortical auditory evoked potential at the beginning of the study and after 3 months of aural rehabilitation. To elicit the responses, simple stimuli (tone burst) and complex stimuli (speech) were used and presented in free field at 70 dB HL. The results were statistically analyzed, and both evaluations were compared. Results  There was no significant difference between the type of eliciting stimulus of the cortical auditory evoked potential for the latency and the amplitude of P1. There was a statistically significant difference in the P1 latency between the evaluations for both stimuli, with reduction of the latency in the second evaluation after 3 months of auditory rehabilitation. There was no statistically significant difference regarding the amplitude of P1 under the two types of stimuli or in the two evaluations. Conclusion  A decrease in latency of the P1 component elicited by both simple and complex stimuli was observed within a three-month interval in children with cochlear implant undergoing aural rehabilitation.

  5. Video outside versus video inside the web: do media setting and image size have an impact on the emotion-evoking potential of video?

    NARCIS (Netherlands)

    Verleur, R.; Verhagen, Pleunes Willem; Crawford, Margaret; Simonson, Michael; Lamboy, Carmen

    2001-01-01

    To explore the educational potential of video-evoked affective responses in a Web-based environment, the question was raised whether video in a Web-based environment is experienced differently from video in a traditional context. An experiment was conducted that studied the affect-evoking power of

  6. Somatosensory and Brainstem Auditory Evoked Potentials Assessed between 4 and 7 Days after Severe Stroke Onset Predict Unfavorable Outcome

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    Yan Zhang

    2015-01-01

    Full Text Available Our objective was to explore the best predictive timing of short-latency somatosensory evoked potentials (SLSEP and brainstem auditory evoked potentials (BAEP for unfavorable outcomes in patients with early stage severe stroke. One hundred fifty-six patients with acute severe supratentorial stroke were monitored according to SLSEP, BAEP, and the Glasgow Coma Scale (GCS at 1–3 days and 4–7 days after the onset of stroke. All patients were followed up for outcomes at 6 months after onset using the modified Rankin Scale (mRS, with a score of 5-6 considered unfavorable. The predictive values of SLSEP, BAEP, and the GCS at 1–3 days were compared with 4–7 days after onset. Our results show that, according to the analysis of prognostic authenticity, the predictive values of SLSEP and BAEP at 4–7 days after stroke onset improved when compared with the values at 1–3 days for unfavorable outcomes. Most of the patients with change of worsening evoked potentials from 1–3 days to 4–7 days after onset had unfavorable outcomes. In conclusion, SLSEP and BAEP assessed at 4–7 days after onset predicted unfavorable outcomes for acute severe stroke patients. The worsening values of SLSEP and BAEP between 1–3 days and 4–7 days also present a prognostic value.

  7. Comparison of Middle Latency Auditory Evoked Potentials in Learning Disability and Normal 7-12 Year- Old Children

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    Shoreh Jalaei

    2007-12-01

    Full Text Available Background and Aim: Learning disability(LD is one of the most prevalent problems among elementary school children. Approximately 10 percent of all elementary school children suffer from this problem. It has been determined that learning disability is predominantly accompanied with subtle impairment in central auditory nervous system. The main idea of this study was to evaluate middle latency auditory evoked potential (MLAEPs in learning disabled children. Materials and Method: This cross-sectional study investigated middle latency auditory evoked potential in children with learning disability (n = 31 compared to normal children (n = 31. Latencies and amplitudes of MLAEPs results with different stimulus intensity and binaural stimulation were compared between two groups. Results: Compared to control group, learning disabled children exhibited smaller amplitudes for all the components except the right ear Na and Pa. There is no significant difference between two groups for latencies of the components. Conclusion: It seems that middle latency auditory evoked potential may be useful in diagnosis and evaluation of learning disabled children although more investigation is required.

  8. Different Effects of Implicit and Explicit Motor Sequence Learning on Latency of Motor Evoked Potential Evoked by Transcranial Magnetic Stimulation on the Primary Motor Cortex.

    Science.gov (United States)

    Hirano, Masato; Kubota, Shinji; Koizume, Yoshiki; Tanaka, Shinya; Funase, Kozo

    2016-01-01

    Motor training induces plastic changes in the primary motor cortex (M1). However, it is unclear whether and how the latency of motor-evoked potentials (MEP) and MEP amplitude are affected by implicit and/or explicit motor learning. Here, we investigated the changes in M1 excitability and MEP latency induced by implicit and explicit motor learning. The subjects performed a serial reaction time task (SRTT) with their five fingers. In this task, visual cues were lit up sequentially along with a predetermined order. Through training, the subjects learned the order of sequence implicitly and explicitly. Before and after the SRTT, we recorded MEP at 25 stimulation points around the hot spot for the flexor pollicis brevis (FPB) muscle. Although no changes in MEP amplitude were observed in either session, we found increases in MEP latency and changes in histogram of MEP latency after implicit learning. Our results suggest that reorganization across the motor cortices occurs during the acquisition of implicit knowledge. In contrast, acquisition of explicit knowledge does not appear to induce the reorganization based on the measures we recorded. The fact that the above mentioned increases in MEP latency occurred without any alterations in MEP amplitude suggests that learning has different effects on different physiological signals. In conclusion, our results propose that analyzing a combination of some indices of M1 excitability, such as MEP amplitude and MEP latency, is encouraged in order to understand plasticity across motor cortices.

  9. Action potential properties are gravity dependent

    Science.gov (United States)

    Meissner, Klaus; Hanke, Wolfgang

    2005-06-01

    The functional properties of neuronal tissue critically depend on cellular composition and intercellular comunication. A basic principle of such communication found in various types of neurons is the generation of action potentials (APs). These APs depend on the presence of voltage gated ion channels and propagate along cellular processes (e.g. axons) towards target neurons or other cells. It has already been shown that the properties of ion channels depend on gravity. To discover whether the properties of APs also depend on gravity, we examined the propagation of APs in earthworms (invertebrates) and isolated nerve fibres (i.e. bundles of axons) from earthworms under conditions of micro- and macro-gravity. In a second set of experiments we could verify our results on rat axons (vertebrates). Our experiments carried out during two parabolic flight campaigns revealed that microgravity slows AP propagation velocity and macrogravity accelerates the transmission of action potentials. The relevance for live-science related questions is considerable, taking into account that altered gravity conditions might affect AP velocity in man during space flight missions.

  10. Seeing One's Own Painful Hand Positioned in the Contralateral Space Reduces Subjective Reports of Pain and Modulates Laser Evoked Potentials.

    Science.gov (United States)

    Valentini, Elia; Koch, Katharina; Aglioti, Salvatore Maria

    2015-06-01

    Studies report that viewing the body or keeping one's arms crossed while receiving painful stimuli may have an analgesic effect. Interestingly, changes in ratings of pain are accompanied by a reduction of brain metabolism or of laser evoked potentials amplitude. What remains unknown is the link between visual analgesia and crossed-arms related analgesia. Here, we investigated pain perception and laser evoked potentials in 3 visual contexts while participants kept their arms in a crossed or uncrossed position during vision of 1) one's own hand, 2) a neutral object in the same spatial location, and 3) a fixation cross placed in front of the participant. We found that having vision of the affected body part in the crossed-arms position was associated with a significant reduction in pain reports. However, no analgesic effect of having vision of the hand in an uncrossed position or of crossing the arms alone was found. The increase of the late vertex laser evoked potential P2 amplitude indexed a general effect of vision of the hand. Our results hint at a complex interaction between cross-modal input and body representation in different spatial frames of reference and at the same time question the effect of visual analgesia and crossed-arms analgesia alone. We found that nociceptive stimuli delivered to the hand in a crossed-arms position evoke less pain than in a canonical anatomic position. Yet we report no significant analgesic effect of vision or crossing the arms on their own. These findings foster the integration of visuospatial and proprioceptive information in rehabilitation protocols. Copyright © 2015 American Pain Society. Published by Elsevier Inc. All rights reserved.

  11. Transcranial motor evoked potential waveform changes in corrective fusion for adolescent idiopathic scoliosis.

    Science.gov (United States)

    Kobayashi, Kazuyoshi; Imagama, Shiro; Ito, Zenya; Ando, Kei; Hida, Tetsuro; Ito, Kenyu; Tsushima, Mikito; Ishikawa, Yoshimoto; Matsumoto, Akiyuki; Nishida, Yoshihiro; Ishiguro, Naoki

    2017-01-01

    OBJECTIVE Corrective surgery for spinal deformities can lead to neurological complications. Several reports have described spinal cord monitoring in surgery for spinal deformity, but only a few have included patients younger than 20 years with adolescent idiopathic scoliosis (AIS). The goal of this study was to evaluate the characteristics of cases with intraoperative transcranial motor evoked potential (Tc-MEP) waveform deterioration during posterior corrective fusion for AIS. METHODS A prospective database was reviewed, comprising 68 patients with AIS who were treated with posterior corrective fusion in a prospective database. A total of 864 muscles in the lower extremities were chosen for monitoring, and acceptable baseline responses were obtained from 819 muscles (95%). Intraoperative Tc-MEP waveform deterioration was defined as a decrease in intraoperative amplitude of ≥ 70% of the control waveform. Age, Cobb angle, flexibility, operative time, estimated blood loss (EBL), intraoperative body temperature, blood pressure, number of levels fused, and correction rate were examined in patients with and without waveform deterioration. RESULTS The patients (3 males and 65 females) had an average age of 14.4 years (range 11-19 years). The mean Cobb angles before and after surgery were 52.9° and 11.9°, respectively, giving a correction rate of 77.4%. Fourteen patients (20%) exhibited an intraoperative waveform change, and these occurred during incision (14%), after screw fixation (7%), during the rotation maneuver (64%), during placement of the second rod after the rotation maneuver (7%), and after intervertebral compression (7%). Most waveform changes recovered after decreased correction or rest. No patient had a motor deficit postoperatively. In multivariate analysis, EBL (OR 1.001, p = 0.085) and number of levels fused (OR 1.535, p = 0.045) were associated with waveform deterioration. CONCLUSIONS Waveform deterioration commonly occurred during rotation maneuvers

  12. The impact of several craniotomies on transcranial motor evoked potential monitoring during neurosurgery.

    Science.gov (United States)

    Tomio, Ryosuke; Akiyama, Takenori; Toda, Masahiro; Ohira, Takayuki; Yoshida, Kazunari

    2017-09-01

    OBJECTIVE Transcranial motor evoked potential (tMEP) monitoring is popular in neurosurgery; however, the accuracy of tMEP can be impaired by craniotomy. Each craniotomy procedure and changes in the CSF levels affects the current spread. The aim of this study was to investigate the influence of several craniotomies on tMEP monitoring by using C3-4 transcranial electrical stimulation (TES). METHODS The authors used the finite element method to visualize the electric field in the brain, which was generated by TES, using realistic 3D head models developed from T1-weighted MR images. Surfaces of 5 layers of the head (brain, CSF, skull, subcutaneous fat, and skin layer) were separated as accurately as possible. The authors created 5 models of the head, as follows: normal head; frontotemporal craniotomy; parietal craniotomy; temporal craniotomy; and occipital craniotomy. The computer simulation was investigated by finite element methods, and clinical recordings of the stimulation threshold level of upper-extremity tMEP (UE-tMEP) during neurosurgery were also studied in 30 patients to validate the simulation study. RESULTS Bone removal during the craniotomy positively affected the generation of the electric field in the motor cortex if the motor cortex was just under the bone at the margin of the craniotomy window. This finding from the authors' simulation study was consistent with clinical reports of frontotemporal craniotomy cases. A major decrease in CSF levels during an operation had a significantly negative impact on the electric field when the motor cortex was exposed to air. The CSF surface level during neurosurgery depends on the body position and location of the craniotomy. The parietal craniotomy and temporal craniotomy were susceptible to the effect of the changing CSF level, based on the simulation study. A marked increase in the threshold following a decrease in CSF was actually recorded in clinical reports of the UE-tMEP threshold from a temporal craniotomy

  13. Effect of Different References on Auditory-Evoked Potentials in Children with Cochlear Implants

    Directory of Open Access Journals (Sweden)

    Maojin Liang

    2017-12-01

    Full Text Available Background: Nose reference (NR, mastoid reference (MR, and montage average reference (MAR are usually used in auditory event-related potential (AEP studies with a recently developed reference electrode standardization technique (REST, which may reduce the reference effect. For children with cochlear implants (CIs, auditory deprivation may hinder normal development of the auditory cortex, and the reference effect may be different between CIs and a normal developing group.Methods: Thirteen right-side-CI children were recruited, comprising 7 males and 6 females, ages 2–5 years, with CI usage of ~1 year. Eleven sex- and age-matched healthy children were recruited for normal controls; 1,000 Hz pure tone evoked AEPs were recorded, and the data were re-referenced to NR, left mastoid reference (LMR, which is the opposite side of the implanted cochlear, MAR, and REST. CI artifact and P1–N1 complex (latency, amplitudes at Fz were analyzed.Results: Confirmed P1–N1 complex could be found in Fz using NR, LMR, MAR, and REST with a 128-electrode scalp. P1 amplitude was larger using LMR than MAR and NR, while no statistically significant difference was found between NR and MAR in the CI group; REST had no significant difference with the three other references. In the control group, no statistically significant difference was found with different references. Group difference of P1 amplitude could be found when using MR, MAR, and REST. For P1 latency, no significant difference among the four references was shown, whether in the CI or control group. Group difference in P1 latency could be found in MR and MAR. N1 amplitude in LMR was significantly lower than NR and MAR in the control group. LMR, MAR, and REST could distinguish the difference in the N1 amplitude between the CI and control group. Contralateral MR or MAR was found to be better in differentiating CI children versus controls. No group difference was found for the artifact component

  14. Beta-zone parapapillary atrophy and multifocal visual evoked potentials in eyes with glaucomatous optic neuropathy

    Science.gov (United States)

    Ketner, Scott; Teng, Christopher C.; Ehrlich, Joshua R.; Raza, Ali S.; Liebmann, Jeffrey M.; Ritch, Robert; Hood, Donald C.

    2015-01-01

    We investigated changes in multifocal visual evoked potential (mfVEP) responses due to beta-zone parapapillary atrophy (βPPA). Patients with glaucomatous optic neuropathy (GON) with or without standard achromatic perimetry (SAP) abnormalities were referred for mfVEP testing during a 2-year period. Eyes with good quality optic disc stereophotographs and reliable SAP results were included. The mfVEP monocular mean latency delays (ms) and amplitudes (SNR) were analyzed. Age, SAP mean deviation (MD), pattern standard deviation (PSD), and spherical equivalent (SE) were analyzed in the multivariate model. Generalized estimated equations were used for comparisons between groups after adjusting for inter-eye associations. Of 394 eyes of 200 patients, 223 (57%) had βPPA. The βPPA eyes were older (59.6 ± 13.7 vs. 56.5 ± 13.7 year, P = 0.02), more myopic (−4.0 ± 3.5 vs. −1.3 ± 3.5 D, P < 0.01), and had poorer SAP scores (MD: −4.9 ± 5.2 vs. −2.6 ± 5.2 dB, P < 0.01; PSD: 4.3 ± 2.9 vs. 2.5 ± 3.0 dB, P < 0.01). By univariate analysis, mean latencies were longer in βPPA eyes (6.1 ± 5.3 vs. 4.0 ± 5.5 ms, P < 0.01). After adjusting for differences in SE, age, and SAP MD, there was no significant difference between the two groups (P = 0.09). βPPA eyes had lower amplitude log SNR (0.49 ± 0.16 vs. 0.56 ± 0.15, P < 0.01), which lost significance (P = 0.51) after adjusting for MD and PSD. Although eyes with βPPA had significantly lower amplitudes and prolonged latencies than eyes without βPPA, these differences were attributable to differences in SAP severity, age, and refractive error. Thus, βPPA does not appear to be an independent factor affecting mfVEP responses in eyes with GON. PMID:21735265

  15. Vestibular evoked myogenic potentials and digital vectoelectronystagmography's study in patients with benign paroxysmal positional vertigo

    Directory of Open Access Journals (Sweden)

    Lira-Batista, Marta Maria da Silva

    2013-04-01

    Full Text Available Introduction: Benign Paroxysmal Positional Vertigo (BPPV is a very common vestibular disorder characterized by brief but intense attacks of rotatory vertigo triggered by simple rapid movement of the head. The integrity of the vestibular pathways can be assessed using tests such as digital vectoelectronystagmography (VENG and vestibular evoked myogenic potentials (VEMP. Aim: This study aimed to determine the VEMP findings with respect to latency, amplitude, and waveform peak to peak and the results of the oculomotor and vestibular components of VENG in patients with BPPV. Method: Although this otoneurological condition is quite common, little is known of the associated VEMP and VENG changes, making it important to research and describe these results. Results: We examined the records of 4438 patients and selected 35 charts after applying the inclusion and exclusion criteria. Of these, 26 patients were women and 9 men. The average age at diagnosis was 52.7 years, and the most prevalent physiological cause, accounting for 97.3% of cases, was ductolithiasis. There was a statistically significant association between normal hearing and mild contralateral sensorineural hearing loss. The results of the oculomotor tests were within the normal reference ranges for all subjects. Patients with BPPV exhibited symmetrical function of the semicircular canals in their synergistic pairs (p < 0.001. The caloric test showed statistically normal responses from the lateral canals. The waveforms of all patients were adequate, but the VEMP results for the data-crossing maneuver with positive positioning showed a trend toward a relationship for the left ear Lp13. There was also a trend towards an association between normal reflexes in the caloric test and the inter-peak VEMP of the left ear. It can be concluded that although there are some differences between the average levels of the VENG and VEMP results, these differences were not statistically significant

  16. Acceptance of background noise, working memory capacity, and auditory evoked potentials in subjects with normal hearing.

    Science.gov (United States)

    Brännström, K Jonas; Zunic, Edita; Borovac, Aida; Ibertsson, Tina

    2012-01-01

    The acceptable noise level (ANL) test is a method for quantifying the amount of background noise that subjects accept when listening to speech. Large variations in ANL have been seen between normal-hearing subjects and between studies of normal-hearing subjects, but few explanatory variables have been identified. To explore a possible relationship between a Swedish version of the ANL test, working memory capacity (WMC), and auditory evoked potentials (AEPs). ANL, WMC, and AEP were tested in a counterbalanced order across subjects. Twenty-one normal-hearing subjects participated in the study (14 females and 7 males; aged 20-39 yr with an average of 25.7 yr). Reported data consists of age, pure-tone average (PTA), most comfortable level (MCL), background noise level (BNL), ANL (i.e., MCL - BNL), AEP latencies, AEP amplitudes, and WMC. Spearman's rank correlation coefficient was calculated between the collected variables to investigate associations. A principal component analysis (PCA) with Varimax rotation was conducted on the collected variables to explore underlying factors and estimate interactions between the tested variables. Subjects were also pooled into two groups depending on their results on the WMC test, one group with a score lower than the average and one with a score higher than the average. Comparisons between these two groups were made using the Mann-Whitney U-test with Bonferroni correction for multiple comparisons. A negative association was found between ANL and WMC but not between AEP and ANL or WMC. Furthermore, ANL is derived from MCL and BNL, and a significant positive association was found between BNL and WMC. However, no significant associations were seen between AEP latencies and amplitudes and the demographic variables, MCL, and BNL. The PCA identified two underlying factors: One that contained MCL, BNL, ANL, and WMC and another that contained latency for wave Na and amplitudes for waves V and Na-Pa. Using the variables in the first factor

  17. High test-retest-reliability of pain-related evoked potentials (PREP) in healthy subjects.

    Science.gov (United States)

    Özgül, Özüm Simal; Maier, Christoph; Enax-Krumova, Elena K; Vollert, Jan; Fischer, Marc; Tegenthoff, Martin; Höffken, Oliver

    2017-04-24

    Pain-related evoked potentials (PREP) is an established electrophysiological method to evaluate the signal transmission of electrically stimulated A-delta fibres. Although prerequisite for its clinical use, test-retest-reliability and side-to-side differences of bilateral stimulation in healthy subjects have not been examined yet. We performed PREP twice within 3-14days in 33 healthy subjects bilaterally by stimulating the dorsal hand. Detection (DT) and pain thresholds (PT) after electrical stimulation, the corresponding pain ratings, latencies of P0, N1, P1 and N2 components and the corresponding amplitudes were assessed. Impact of electrically induced pain intensity, age, sex, and arm length on PREP was analysed. MANOVA, t-Test, interclass correlation coefficient (ICC), standard error of measurement (SEM), smallest real difference (SRD), Bland-Altmann-Analysis as well as ANCOVA were used for statistical analysis. Measurement from both sides on both days resulted in mean N1-latencies from 142.39±18.12ms to 144.03±16.62ms and in mean N1P1-amplitudes from 39.04±12.26μV to 40.53±12.9μV. Analysis of a side-to-side effect showed for the N1-latency a F-value of 0.038 and for the N1P1-amplitude of 0.004 (p>0.8). We found intraclass correlation coefficients (ICC) from 0.88 to 0.93 and a standard error of measurement (SEM)test-retest-reliability for N1-latency and N1P1-amplitude without systematic error and there was no side-to-side effect on PREP. N1-latency (r=0.35, ptest-retest-reliability and negligible side-to-side differences concerning the commonly used parameters N1-latency and N1P1-amplitude. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Cortical evoked potential and extracellular K+ and H+ at critical levels of brain ischemia

    DEFF Research Database (Denmark)

    Astrup, J; Symon, L; Branston, N M

    1977-01-01

    As shown previously, the electrical function of the brain is critically dependent on cerebral blood flow in the sense that reduction beyond an ischemic threshold of approximately 15 ml/100 gm per minute (approximately 35% of control) in the baboon leads to complete failure of the somatosensory...... evoked response. This study tests the hypothesis that electrical failure in ischemia may be directly associated with a massive release of intracellular K+ or with a critical degree of extracellular acidosis. By microelectrode techniques, measurements of blood flow, extracellular activity of K+ and H...... local cerebral blood flow proportionally. Abolition of evoked response could not be explained by depolarization by release of intracellular K+, nor was it critically dependent on cortical pH. However, the massive release of intracellular K+ was by itself critically dependent on cortical blood flow...

  19. Ocular vestibular-evoked myogenic potentials (oVEMPs) require extraocular muscles but not facial or cochlear nerve activity.

    Science.gov (United States)

    Chihara, Yasuhiro; Iwasaki, Shinichi; Ushio, Munetaka; Fujimoto, Chisato; Kashio, Akinori; Kondo, Kenji; Ito, Ken; Asakage, Takahiro; Yamasoba, Tatsuya; Kaga, Kimitaka; Murofushi, Toshihisa

    2009-03-01

    Cervical vestibular evoked myogenic potentials (cVEMPs) have been found to be useful for clinical testing of vestibular function. Recently, investigators showed that short-latency, initially negative surface EMG potentials can be recorded around the extraocular muscles (oVEMPs) in response to air-conducted sound (ACS), bone-conducted vibration (BCV), and head taps. Although these evoked potentials, which are located around the eyes, most likely originate primarily from the otolith-ocular pathway, the possibility of contamination by other nerve activities cannot be completely eliminated. The purpose of the present study was to clarify the origin of oVEMPs by examining these possibilities using clinical findings. Twelve healthy subjects and 15 patients were enrolled. Of the 15 patients, 3 patients had undergone exenteration of the unilateral intraorbital contents, one had undergone exenteration of the right eyeball with preservation of extraocular muscles, 5 had facial palsy, and 6 had profound hearing loss. ACS and/or BCV were used in these subjects. Exenteration of the unilateral intraorbital contents resulted in absence of myogenic potentials on the affected side. On the other hand, exenteration of the eyeball with preservation of extraocular muscles did not have a major impact on the responses. There were no significant differences in the waveforms between healthy subjects and patients with facial palsy or profound hearing loss. The results suggested that short-latency, initially negative evoked potentials recorded below the eyes are not affected by cochlear or facial nerve activities and are dependent on the presence of extraocular muscles. This study provides the evidence that oVEMPs originate from exraocular muscles activated through the vestibulo-ocular pathway.

  20. Short latency compound action potentials from mammalian gravity receptor organs

    Science.gov (United States)

    Jones, T. A.; Jones, S. M.

    1999-01-01

    Gravity receptor function was characterized in four mammalian species using far-field vestibular evoked potentials (VsEPs). VsEPs are compound action potentials of the vestibular nerve and central relays that are elicited by linear acceleration ramps applied to the cranium. Rats, mice, guinea pigs, and gerbils were studied. In all species, response onset occurred within 1.5 ms of the stimulus onset. Responses persisted during intense (116 dBSPL) wide-band (50 to 50 inverted question mark omitted inverted question mark000 Hz) forward masking, whereas auditory responses to intense clicks (112 dBpeSPL) were eliminated under the same conditions. VsEPs remained after cochlear extirpation but were eliminated following bilateral labyrinthectomy. Responses included a series of positive and negative peaks that occurred within 8 ms of stimulus onset (range of means at +6 dBre: 1.0 g/ms: P1=908 to 1062 micros, N1=1342 to 1475 micros, P2=1632 to 1952 micros, N2=2038 to 2387 micros). Mean response amplitudes at +6 dBre: 1.0 g/ms ranged from 0.14 to 0.99 microV. VsEP input/output functions revealed latency slopes that varied across peaks and species ranging from -19 to -51 micros/dB. Amplitude-intensity slopes also varied ranging from 0.04 to 0.08 microV/dB for rats and mice. Latency values were comparable to those of birds although amplitudes were substantially smaller in mammals. VsEP threshold values were considerably higher in mammals compared to birds and ranged from -8.1 to -10.5 dBre 1.0 g/ms across species. These results support the hypothesis that mammalian gravity receptors are less sensitive to dynamic stimuli than are those of birds.

  1. Auditory Evoked Potentials for the Evaluation of Hearing Sensitivity in Navy Dolphins. Modification P00002: Assessment of Hearing Sensitivity in Adult Male Elephant Seals

    National Research Council Canada - National Science Library

    Houser, Dorian S

    2006-01-01

    A custom auditory evoked potential (AEP) system was used to assess the feasibility of rapidly testing the hearing of bottlenose dolphins by tracking the magnitude of the envelope following response (EFR...

  2. Auditory Evoked Potentials for the Evaluation of Hearing Sensitivity in Navy Dolphins. Assessment of Hearing Sensitivity in Adult Male Elephant Seals

    National Research Council Canada - National Science Library

    Houser, Dorian S

    2006-01-01

    A custom auditory evoked potential (AEP) system was used to assess the feasibility of rapidly testing the hearing of bottlenose dolphins by tracking the magnitude of the envelope following response (EFR...

  3. Monophasic action potentials and activation recovery intervals as measures of ventricular action potential duration: experimental evidence to resolve some controversies

    NARCIS (Netherlands)

    Coronel, Ruben; de Bakker, Jacques M. T.; Wilms-Schopman, Francien J. G.; Opthof, Tobias; Linnenbank, André C.; Belterman, Charly N.; Janse, Michiel J.

    2006-01-01

    BACKGROUND: Activation recovery intervals (ARIs) and monophasic action potential (MAP) duration are used as measures of action potential duration in beating hearts. However, controversies exist concerning the correct way to record MAPs or calculate ARIs. We have addressed these issues

  4. Dynamic causal modeling of touch-evoked potentials in the rubber hand illusion.

    Science.gov (United States)

    Zeller, Daniel; Friston, Karl J; Classen, Joseph

    2016-09-01

    The neural substrate of bodily ownership can be disclosed by the rubber hand illusion (RHI); namely, the illusory self-attribution of an artificial hand that is induced by synchronous tactile stimulation of the subject's hand that is hidden from view. Previous studies have pointed to the premotor cortex (PMC) as a pivotal area in such illusions. To investigate the effective connectivity between - and within - sensory and premotor areas involved in bodily perceptions, we used dynamic causal modeling of touch-evoked responses in 13 healthy subjects. Each subject's right hand was stroked while viewing their own hand ("REAL"), or an artificial hand presented in an anatomically plausible ("CONGRUENT") or implausible ("INCONGRUENT") position. Bayesian model comparison revealed strong evidence for a differential involvement of the PMC in the generation of touch-evoked responses under the three conditions, confirming a crucial role of PMC in bodily self-attribution. In brief, the extrinsic (forward) connection from left occipital cortex to left PMC was stronger for CONGRUENT and INCONGRUENT as compared to REAL, reflecting the augmentation of bottom-up visual input when multisensory integration is challenged. Crucially, intrinsic connectivity in the primary somatosensory cortex (S1) was attenuated in the CONGRUENT condition, during the illusory percept. These findings support predictive coding models of the functional architecture of multisensory integration (and attenuation) in bodily perceptual experience. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Objective measures of binaural masking level differences and comodulation masking release based on late auditory evoked potentials.

    Science.gov (United States)

    Epp, Bastian; Yasin, Ifat; Verhey, Jesko L

    2013-12-01

    The audibility of important sounds is often hampered due to the presence of other masking sounds. The present study investigates if a correlate of the audibility of a tone masked by noise is found in late auditory evoked potentials measured from human listeners. The audibility of the target sound at a fixed physical intensity is varied by introducing auditory cues of (i) interaural target signal phase disparity and (ii) coherent masker level fluctuations in different frequency regions. In agreement with previous studies, psychoacoustical experiments showed that both stimulus manipulations result in a masking release (i: binaural masking level difference; ii: comodulation masking release) compared to a condition where those cues are not present. Late auditory evoked potentials (N1, P2) were recorded for the stimuli at a constant masker level, but different signal levels within the same set of listeners who participated in the psychoacoustical experiment. The data indicate differences in N1 and P2 between stimuli with and without interaural phase disparities. However, differences for stimuli with and without coherent masker modulation were only found for P2, i.e., only P2 is sensitive to the increase in audibility, irrespective of the cue that caused the masking release. The amplitude of P2 is consistent with the psychoacoustical finding of an addition of the masking releases when both cues are present. Even though it cannot be concluded where along the auditory pathway the audibility is represented, the P2 component of auditory evoked potentials is a candidate for an objective measure of audibility in the human auditory system. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Monitoring auditory cortical plasticity in hearing aid users with long latency auditory evoked potentials: a longitudinal study.

    Science.gov (United States)

    Leite, Renata Aparecida; Magliaro, Fernanda Cristina Leite; Raimundo, Jeziela Cristina; Bento, Ricardo Ferreira; Matas, Carla Gentile

    2018-02-19

    The objective of this study was to compare long-latency auditory evoked potentials before and after hearing aid fittings in children with sensorineural hearing loss compared with age-matched children with normal hearing. Thirty-two subjects of both genders aged 7 to 12 years participated in this study and were divided into two groups as follows: 14 children with normal hearing were assigned to the control group (mean age 9 years and 8 months), and 18 children with mild to moderate symmetrical bilateral sensorineural hearing loss were assigned to the study group (mean age 9 years and 2 months). The children underwent tympanometry, pure tone and speech audiometry and long-latency auditory evoked potential testing with speech and tone burst stimuli. The groups were assessed at three time points. The study group had a lower percentage of positive responses, lower P1-N1 and P2-N2 amplitudes (speech and tone burst), and increased latencies for the P1 and P300 components following the tone burst stimuli. They also showed improvements in long-latency auditory evoked potentials (with regard to both the amplitude and presence of responses) after hearing aid use. Alterations in the central auditory pathways can be identified using P1-N1 and P2-N2 amplitude components, and the presence of these components increases after a short period of auditory stimulation (hearing aid use). These findings emphasize the importance of using these amplitude components to monitor the neuroplasticity of the central auditory nervous system in hearing aid users.

  7. Action potential broadening in a presynaptic channelopathy

    Science.gov (United States)

    Begum, Rahima; Bakiri, Yamina; Volynski, Kirill E.; Kullmann, Dimitri M.

    2016-07-01

    Brain development and interictal function are unaffected in many paroxysmal neurological channelopathies, possibly explained by homoeostatic plasticity of synaptic transmission. Episodic ataxia type 1 is caused by missense mutations of the potassium channel Kv1.1, which is abundantly expressed in the terminals of cerebellar basket cells. Presynaptic action potentials of small inhibitory terminals have not been characterized, and it is not known whether developmental plasticity compensates for the effects of Kv1.1 dysfunction. Here we use visually targeted patch-clamp recordings from basket cell terminals of mice harbouring an ataxia-associated mutation and their wild-type littermates. Presynaptic spikes are followed by a pronounced afterdepolarization, and are broadened by pharmacological blockade of Kv1.1 or by a dominant ataxia-associated mutation. Somatic recordings fail to detect such changes. Spike broadening leads to increased Ca2+ influx and GABA release, and decreased spontaneous Purkinje cell firing. We find no evidence for developmental compensation for inherited Kv1.1 dysfunction.

  8. MRI of optic nerve and postchiasmal visual pathways and visual evoked potentials in secondary progressive multiple sclerosis

    International Nuclear Information System (INIS)

    Davies, M.B.; Hawkins, C.P.; Williams, R.; Haq, N.; Pelosi, L.

    1998-01-01

    We studied the relationship between abnormalities shown by MRI and functional disturbances in the visual pathway as assessed by the visual evoked potential (VEP) in 25 patients with established multiple sclerosis (MS); only 4 of whom had a history of acute optic neuritis. Optic nerve MRI was abnormal in 19 (76 %) and is thus useful in detecting subclinical disease. Optic nerve total lesion length and area on the STIR sequence was found to correlate significantly with prolongation of the VEP latency. This may reflect a predominantly demyelinating rather than inflammatory origin for the signal change in the optic nerve. (orig.)

  9. Use of the 400 Hz period evoked potential in the prediction of loudness discomfort levels in normal hearing adults.

    Science.gov (United States)

    Nolan, K J; Parker, D J

    2000-01-01

    This study investigated normally-hearing adult subjects to establish whether the 400 Hz Period Evoked Potential (PEP) can be used to predict Loudness Discomfort Level (LDL). Parameter-intensity functions were obtained using the response measures (400 Hz components) of amplitude, phase, magnitude squared coherence (MSC) and phase coherence (PC). The best predictor of the subjective LDL was found to be the gradient of the individual's amplitude-intensity function for significant (MSC > 0.264 and/or PC > 0.525) responses only. In this case 82% are predicted within 10 dB and there is a maximum error of 15 dB.

  10. [Visual evoked potentials produced by monocular flash stimuli in the cerebral cortex of the rabbit. I. Typography].

    Science.gov (United States)

    Pérez-Cobo, J C; Ruiz-Beramendi, M; Pérez-Arroyo, M

    1990-12-01

    The visually evoked potentials in the hemisphere contralateral to the stimulated eye in rabbit, can be described topographically as follows. While a positive wave (P1) begins forming in the anterior zones and in the V I binocular zone, the N0 wave, at times very large, is produced in a more occipital zone, which corresponds to the visual streak. Immediately afterwards, the positivity, P1, practically invades the whole of the hemisphere. After this, the N1 wave which is produced in the most posterior parts of the V I, begins forming. The whole phenomenon comes to an end when the P2 wave is generated in the most occipital zones.

  11. Assessment of otolith function using cervical and ocular vestibular evoked myogenic potentials in individuals with motion sickness.

    Science.gov (United States)

    Singh, Niraj Kumar; Pandey, Preeti; Mahesh, Soumya

    2014-01-01

    The involvement of otolith organs in motion sickness has long been debated; however, equivocal findings exist in literature. The present study thus aimed at evaluating the otolith functioning in individuals with motion sickness. Cervical and ocular vestibular evoked myogenic potentials were recorded from 30 individuals with motion sickness, 30 professional drivers and 30 healthy individuals. The results revealed no significant difference in latencies and amplitudes between the groups (p>0.05). Nonetheless, thresholds were significantly elevated and inter-aural asymmetry ratio significantly higher in motion sickness susceptible group (p otolithic function seem the likely reasons behind motion sickness susceptibility.

  12. A Brain Computer Interface for Robust Wheelchair Control Application Based on Pseudorandom Code Modulated Visual Evoked Potential

    DEFF Research Database (Denmark)

    Mohebbi, Ali; Engelsholm, Signe K.D.; Puthusserypady, Sadasivan

    2015-01-01

    In this pilot study, a novel and minimalistic Brain Computer Interface (BCI) based wheelchair control application was developed. The system was based on pseudorandom code modulated Visual Evoked Potentials (c-VEPs). The visual stimuli in the scheme were generated based on the Gold code......, and the VEPs were recognized and classified using subject-specific algorithms. The system provided the ability of controlling a wheelchair model (LEGO R MINDSTORM R EV3 robot) in 4 different directions based on the elicited c-VEPs. Ten healthy subjects were evaluated in testing the system where an average...

  13. Identification of causal relations between haemodynamic variables, auditory evoked potentials and isoflurane by means of fuzzy logic

    DEFF Research Database (Denmark)

    Jensen, E W; Nebot, A; Caminal, P

    1999-01-01

    The aim of this study was to identify a possible relationship between haemodynamic variables, auditory evoked potentials (AEP) and inspired fraction of isoflurane (ISOFl). Two different models (isoflurane and mean arterial pressure) were identified using the fuzzy inductive reasoning (FIR......) methodology. A fuzzy model is able to identify non-linear and linear components of a causal relationship by means of optimization of information content of available data. Nine young female patients undergoing hysterectomy under general anaesthesia were included. Mean arterial pressure (MAP), heart rate (HR...

  14. Automated single-trial assessment of laser-evoked potentials as an objective functional diagnostic tool for the nociceptive system.

    Science.gov (United States)

    Hatem, S M; Hu, L; Ragé, M; Gierasimowicz, A; Plaghki, L; Bouhassira, D; Attal, N; Iannetti, G D; Mouraux, A

    2012-12-01

    To assess the clinical usefulness of an automated analysis of event-related potentials (ERPs). Nociceptive laser-evoked potentials (LEPs) and non-nociceptive somatosensory electrically-evoked potentials (SEPs) were recorded in 37 patients with syringomyelia and 21 controls. LEP and SEP peak amplitudes and latencies were estimated using a single-trial automated approach based on time-frequency wavelet filtering and multiple linear regression, as well as a conventional approach based on visual inspection. The amplitudes and latencies of normal and abnormal LEP and SEP peaks were identified reliably using both approaches, with similar sensitivity and specificity. Because the automated approach provided an unbiased solution to account for average waveforms where no ERP could be identified visually, it revealed significant differences between patients and controls that were not revealed using the visual approach. The automated analysis of ERPs characterized reliably and objectively LEP and SEP waveforms in patients. The automated single-trial analysis can be used to characterize normal and abnormal ERPs with a similar sensitivity and specificity as visual inspection. While this does not justify its use in a routine clinical setting, the technique could be useful to avoid observer-dependent biases in clinical research. Copyright © 2012 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  15. Motor-Evoked Potentials in the Lower Back Are Modulated by Visual Perception of Lifted Weight.

    Directory of Open Access Journals (Sweden)

    Frank Behrendt

    Full Text Available Facilitation of the primary motor cortex (M1 during the mere observation of an action is highly congruent with the observed action itself. This congruency comprises several features of the executed action such as somatotopy and temporal coding. Studies using reach-grasp-lift paradigms showed that the muscle-specific facilitation of the observer's motor system reflects the degree of grip force exerted in an observed hand action. The weight judgment of a lifted object during action observation is an easy task which is the case for hand actions as well as for lifting boxes from the ground. Here we investigated whether the cortical representation in M1 for lumbar back muscles is modulated due to the observation of a whole-body lifting movement as it was shown for hand action. We used transcranial magnetic stimulation (TMS to measure the corticospinal excitability of the m. erector spinae (ES while subjects visually observed the recorded sequences of a person lifting boxes of different weights from the floor. Consistent with the results regarding hand action the present study reveals a differential modulation of corticospinal excitability despite the relatively small M1 representation of the back also for lifting actions that mainly involve the lower back musculature.

  16. Motor-Evoked Potentials in the Lower Back Are Modulated by Visual Perception of Lifted Weight.

    Science.gov (United States)

    Behrendt, Frank; de Lussanet, Marc H E; Zentgraf, Karen; Zschorlich, Volker R

    2016-01-01

    Facilitation of the primary motor cortex (M1) during the mere observation of an action is highly congruent with the observed action itself. This congruency comprises several features of the executed action such as somatotopy and temporal coding. Studies using reach-grasp-lift paradigms showed that the muscle-specific facilitation of the observer's motor system reflects the degree of grip force exerted in an observed hand action. The weight judgment of a lifted object during action observation is an easy task which is the case for hand actions as well as for lifting boxes from the ground. Here we investigated whether the cortical representation in M1 for lumbar back muscles is modulated due to the observation of a whole-body lifting movement as it was shown for hand action. We used transcranial magnetic stimulation (TMS) to measure the corticospinal excitability of the m. erector spinae (ES) while subjects visually observed the recorded sequences of a person lifting boxes of different weights from the floor. Consistent with the results regarding hand action the present study reveals a differential modulation of corticospinal excitability despite the relatively small M1 representation of the back also for lifting actions that mainly involve the lower back musculature.

  17. Teachers in Action Research: Assumptions and Potentials

    Science.gov (United States)

    Li, Yuen-Ling

    2008-01-01

    Research literature has long indicated that action research may stimulate practitioners themselves to actively evaluate the quality of their practice. This study is designed to report the use of action research for the development of early years professional practice by analyzing the pre-project and the post-project video-filmed teaching events.…

  18. High-frequency combination coding-based steady-state visual evoked potential for brain computer interface

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Feng; Zhang, Xin; Xie, Jun; Li, Yeping; Han, Chengcheng; Lili, Li; Wang, Jing [School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Xu, Guang-Hua [School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); State Key Laboratory for Manufacturing Systems Engineering, Xi’an Jiaotong University, Xi’an 710054 (China)

    2015-03-10

    This study presents a new steady-state visual evoked potential (SSVEP) paradigm for brain computer interface (BCI) systems. The goal of this study is to increase the number of targets using fewer stimulation high frequencies, with diminishing subject’s fatigue and reducing the risk of photosensitive epileptic seizures. The new paradigm is High-Frequency Combination Coding-Based High-Frequency Steady-State Visual Evoked Potential (HFCC-SSVEP).Firstly, we studied SSVEP high frequency(beyond 25 Hz)response of SSVEP, whose paradigm is presented on the LED. The SNR (Signal to Noise Ratio) of high frequency(beyond 40 Hz) response is very low, which is been unable to be distinguished through the traditional analysis method; Secondly we investigated the HFCC-SSVEP response (beyond 25 Hz) for 3 frequencies (25Hz, 33.33Hz, and 40Hz), HFCC-SSVEP produces n{sup n} with n high stimulation frequencies through Frequence Combination Code. Further, Animproved Hilbert-huang transform (IHHT)-based variable frequency EEG feature extraction method and a local spectrum extreme target identification algorithmare adopted to extract time-frequency feature of the proposed HFCC-SSVEP response.Linear predictions and fixed sifting (iterating) 10 time is used to overcome the shortage of end effect and stopping criterion,generalized zero-crossing (GZC) is used to compute the instantaneous frequency of the proposed SSVEP respondent signals, the improved HHT-based feature extraction method for the proposed SSVEP paradigm in this study increases recognition efficiency, so as to improve ITR and to increase the stability of the BCI system. what is more, SSVEPs evoked by high-frequency stimuli (beyond 25Hz) minimally diminish subject’s fatigue and prevent safety hazards linked to photo-induced epileptic seizures, So as to ensure the system efficiency and undamaging.This study tests three subjects in order to verify the feasibility of the proposed method.

  19. Test-Retest Reliability of Dual-Recorded Brainstem versus Cortical Auditory-Evoked Potentials to Speech.

    Science.gov (United States)

    Bidelman, Gavin M; Pousson, Monique; Dugas, Calli; Fehrenbach, Amy

    2018-02-01

    Auditory-evoked potentials have proven useful in the objective evaluation of sound encoding at different stages of the auditory pathway (brainstem and cortex). Yet, their utility for use in clinical assessment and empirical research relies critically on the precision and test-retest repeatability of the measure. To determine how subcortical/cortical classes of auditory neural responses directly compare in terms of their internal consistency and test-retest reliability within and between listeners. A descriptive cohort study describing the dispersion of electrophysiological measures. Eight young, normal-hearing female listeners. We recorded auditory brainstem responses (ABRs), brainstem frequency-following responses (FFRs), and cortical (P1-N1-P2) auditory-evoked potentials elicited by speech sounds in the same set of listeners. We reassessed responses within each of four different test sessions over a period of 1 mo, allowing us to detect possible changes in latency/amplitude characteristics with finer detail than in previous studies. Our findings show that brainstem and cortical amplitude/latency measures are remarkably stable; with the exception of slight prolongation of the P1 wave, we found no significant variation in any response measure. Intraclass correlation analysis revealed that the speech-evoked FFR amplitude and latency measures achieved superior repeatability (intraclass correlation coefficient >0.85) among the more widely used obligatory brainstem (ABR) and cortical (P1-N1-P2) auditory-evoked potentials. Contrasting these intersubject effects, intrasubject variability (i.e., within-subject coefficient of variation) revealed that while latencies were more stable than amplitudes, brainstem and cortical responses did not differ in their variability at the single subject level. We conclude that (1) the variability of auditory neural responses increases with ascending level along the auditory neuroaxis (cortex > brainstem) between subjects but remains

  20. Proprioceptive evoked gamma oscillations

    DEFF Research Database (Denmark)

    Arnfred, Sidse M; Hansen, Lars Kai; Parnas, Josef

    2007-01-01

    A proprioceptive stimulus consisting of a weight change of a handheld load has recently been shown to elicit an evoked potential. Previously, somatosensory gamma oscillations have only been evoked by electrical stimuli. We conjectured that a natural proprioceptive stimulus also would be able...

  1. A pilot study to record visual evoked potentials during prone spine surgery using the SightSaver™ photic visual stimulator.

    Science.gov (United States)

    Soffin, E M; Emerson, R G; Cheng, J; Mercado, K; Smith, K; Beckman, J D

    2017-12-20

    This is a pilot study to assess the clinical safety and efficacy of recording real-time flash visual evoked potentials (VEPs) using the SightSaver TM Visual Stimulator mask during prone spine surgery. A prospective, observational pilot study. Twenty patients presenting for spine surgery (microdiscectomy, 1-2 level lumbar fusion, or > 2 levels thoraco-lumbar fusion) were enrolled. The SightSaver™ Visual Stimulator™ was used to elicit VEPs throughout surgery. Somatosensory evoked potentials (SSEPs) were simultaneously recorded. All patients underwent general anesthesia with a combination of intravenous and inhaled agents. The presence, absence, and changes in VEP were qualitatively analyzed. Reproducible VEPs were elicited in 18/20 patients (36/40 eyes). VEPs were exquisitely sensitive to changes in anesthesia and decayed with rising MAC of isoflurane and/or N 2 O. Decrements in VEPs were observed without concomitant changes in SSEPs. The mask was simple to apply and use and was not associated with adverse effects. The SightSaver™ mask represents an emerging technology for monitoring developing visual insults during surgery. The definitive applications remain to be determined, but likely include use in select patients and/or surgeries. Here, we have validated the device as safe and effective, and show that VEPs can be recorded in real time under general anesthesia in the prone position. Future studies should be directed towards understanding the ideal anesthetic regimen to facilitate stable VEP recording during prone spine surgery.

  2. Passive language mapping combining real-time oscillation analysis with cortico-cortical evoked potentials for awake craniotomy.

    Science.gov (United States)

    Tamura, Yukie; Ogawa, Hiroshi; Kapeller, Christoph; Prueckl, Robert; Takeuchi, Fumiya; Anei, Ryogo; Ritaccio, Anthony; Guger, Christoph; Kamada, Kyousuke

    2016-12-01

    OBJECTIVE Electrocortical stimulation (ECS) is the gold standard for functional brain mapping; however, precise functional mapping is still difficult in patients with language deficits. High gamma activity (HGA) between 80 and 140 Hz on electrocorticography is assumed to reflect localized cortical processing, whereas the cortico-cortical evoked potential (CCEP) can reflect bidirectional responses evoked by monophasic pulse stimuli to the language cortices when there is no patient cooperation. The authors propose the use of "passive" mapping by combining HGA mapping and CCEP recording without active tasks during conscious resections of brain tumors. METHODS Five patients, each with an intraaxial tumor in their dominant hemisphere, underwent conscious resection of their lesion with passive mapping. The authors performed functional localization for the receptive language area, using real-time HGA mapping, by listening passively to linguistic sounds. Furthermore, single electrical pulses were delivered to the identified receptive temporal language area to detect CCEPs in the frontal lobe. All mapping results were validated by ECS, and the sensitivity and specificity were evaluated. RESULTS Linguistic HGA mapping quickly identified the language area in the temporal lobe. Electrical stimulation by linguistic HGA mapping to the identified temporal receptive language area evoked CCEPs on the frontal lobe. The combination of linguistic HGA and frontal CCEPs needed no patient cooperation or effort. In this small case series, the sensitivity and specificity were 93.8% and 89%, respectively. CONCLUSIONS The described technique allows for simple and quick functional brain mapping with higher sensitivity and specificity than ECS mapping. The authors believe that this could improve the reliability of functional brain mapping and facilitate rational and objective operations. Passive mapping also sheds light on the underlying physiological mechanisms of language in the human brain.

  3. Active action potential propagation but not initiation in thalamic interneuron dendrites

    Science.gov (United States)

    Casale, Amanda E.; McCormick, David A.

    2012-01-01

    Inhibitory interneurons of the dorsal lateral geniculate nucleus of the thalamus modulate the activity of thalamocortical cells in response to excitatory input through the release of inhibitory neurotransmitter from both axons and dendrites. The exact mechanisms by which release can occur from dendrites are, however, not well understood. Recent experiments using calcium imaging have suggested that Na/K based action potentials can evoke calcium transients in dendrites via local active conductances, making the back-propagating action potential a candidate for dendritic neurotransmitter release. In this study, we employed high temporal and spatial resolution voltage-sensitive dye imaging to assess the characteristics of dendritic voltage deflections in response to Na/K action potentials in interneurons of the mouse dorsal lateral geniculate nucleus. We found that trains or single action potentials elicited by somatic current injection or local synaptic stimulation led to action potentials that rapidly and actively back-propagated throughout the entire dendritic arbor and into the fine filiform dendritic appendages known to release GABAergic vesicles. Action potentials always appeared first in the soma or proximal dendrite in response to somatic current injection or local synaptic stimulation, and the rapid back-propagation into the dendritic arbor depended upon voltage-gated sodium and TEA-sensitive potassium channels. Our results indicate that thalamic interneuron dendrites integrate synaptic inputs that initiate action potentials, most likely in the axon initial segment, that then back-propagate with high-fidelity into the dendrites, resulting in a nearly synchronous release of GABA from both axonal and dendritic compartments. PMID:22171033

  4. Single-trial detection of visual evoked potentials by common spatial patterns and wavelet filtering for brain-computer interface.

    Science.gov (United States)

    Tu, Yiheng; Huang, Gan; Hung, Yeung Sam; Hu, Li; Hu, Yong; Zhang, Zhiguo

    2013-01-01

    Event-related potentials (ERPs) are widely used in brain-computer interface (BCI) systems as input signals conveying a subject's intention. A fast and reliable single-trial ERP detection method can be used to develop a BCI system with both high speed and high accuracy. However, most of single-trial ERP detection methods are developed for offline EEG analysis and thus have a high computational complexity and need manual operations. Therefore, they are not applicable to practical BCI systems, which require a low-complexity and automatic ERP detection method. This work presents a joint spatial-time-frequency filter that combines common spatial patterns (CSP) and wavelet filtering (WF) for improving the signal-to-noise (SNR) of visual evoked potentials (VEP), which can lead to a single-trial ERP-based BCI.

  5. Tradeoff between User Experience and BCI Classification Accuracy with Frequency Modulated Steady-State Visual Evoked Potentials.

    Science.gov (United States)

    Dreyer, Alexander M; Herrmann, Christoph S; Rieger, Jochem W

    2017-01-01

    Steady-state visual evoked potentials (SSVEPs) have been widely employed for the control of brain-computer interfaces (BCIs) because they are very robust, lead to high performance, and allow for a high number of commands. However, such flickering stimuli often also cause user discomfort and fatigue, especially when several light sources are used simultaneously. Different variations of SSVEP driving signals have been proposed to increase user comfort. Here, we investigate the suitability of frequency modulation of a high frequency carrier for SSVEP-BCIs. We compared BCI performance and user experience between frequency modulated (FM) and traditional sinusoidal (SIN) SSVEPs in an offline classification paradigm with four independently flickering light-emitting diodes which were overtly attended (fixated). While classification performance was slightly reduced with the FM stimuli, the user comfort was significantly increased. Comparing the SSVEPs for covert attention to the stimuli (without fixation) was not possible, as no reliable SSVEPs were evoked. Our results reveal that several, simultaneously flickering, light emitting diodes can be used to generate FM-SSVEPs with different frequencies and the resulting occipital electroencephalography (EEG) signals can be classified with high accuracy. While the performance we report could be further improved with adjusted stimuli and algorithms, we argue that the increased comfort is an important result and suggest the use of FM stimuli for future SSVEP-BCI applications.

  6. Noise Enhances Action Potential Generation in Mouse Sensory Neurons via Stochastic Resonance.

    Science.gov (United States)

    Onorato, Irene; D'Alessandro, Giuseppina; Di Castro, Maria Amalia; Renzi, Massimiliano; Dobrowolny, Gabriella; Musarò, Antonio; Salvetti, Marco; Limatola, Cristina; Crisanti, Andrea; Grassi, Francesca

    2016-01-01

    Noise can enhance perception of tactile and proprioceptive stimuli by stochastic resonance processes. However, the mechanisms underlying this general phenomenon remain to be characterized. Here we studied how externally applied noise influences action potential firing in mouse primary sensory neurons of dorsal root ganglia, modelling a basic process in sensory perception. Since noisy mechanical stimuli may cause stochastic fluctuations in receptor potential, we examined the effects of sub-threshold depolarizing current steps with superimposed random fluctuations. We performed whole cell patch clamp recordings in cultured neurons of mouse dorsal root ganglia. Noise was added either before and during the step, or during the depolarizing step only, to focus onto the specific effects of external noise on action potential generation. In both cases, step + noise stimuli triggered significantly more action potentials than steps alone. The normalized power norm had a clear peak at intermediate noise levels, demonstrating that the phenomenon is driven by stochastic resonance. Spikes evoked in step + noise trials occur earlier and show faster rise time as compared to the occasional ones elicited by steps alone. These data suggest that external noise enhances, via stochastic resonance, the recruitment of transient voltage-gated Na channels, responsible for action potential firing in response to rapid step-wise depolarizing currents.

  7. Dose and timing effect of etomidate on motor evoked potentials elicited by transcranial electric or magnetic stimulation in the monkey and baboon.

    Science.gov (United States)

    Sloan, Tod; Rogers, J

    2009-08-01

    Etomidate has been shown to both enhance and depress the cortical amplitude of somatosensory evoked potentials (SSEP) depending on the dose used. Similar amplitude increases with etomidate and motor evoked potentials resulting from cortical magnetic (tcMMEP) and electric (tcEMEP) stimulation have not been consistent. We used a primate model to elucidate the time and dose characteristics of the effect. tcMMEP and tcEMEP were characterized during bolus injections of 0.1-1.8 mg/kg etomidate in 10 adult cynomologous monkeys during a baseline anesthesia with a continuous ketamine infusion. Responses were assessed by measuring the amplitude and onset latency of the hypothenar compound action potential response. In a second experiment the epidural and hypothenar response to tcEMEP was recorded under 0.3% isoflurane anesthesia and following intravenous injection of 0.05-0.35 mg/kg etomidate. Cortical stimulation was accomplished using a Cadwell MES-10 (tcMMEP) and Digitimer D180 (tcEMEP). The amplitude of the hypothenar muscle response was increased for tcEMEP and tcMMEP at 20 min following 0.1 mg/kg etomidate in the monkey. The amplification of the tcMMEP response was significantly greater than the tcEMEP response (1.95 + 0.62 SD vs. 1.43 + 0.68 SD, P = 0.023). Responses at higher doses were all below baseline. The tcMMEP response was significantly smaller than the tcEMEP at doses above 0.9 mg/kg (all P<0.001). The onset latency values were not significantly increased at any dose or time. The epidural recording demonstrated a large increase in the number of I waves compared to the isoflurane baseline. This study demonstrates that a low dose (0.1 mg/kg) of etomidate increases the com- pound muscle action potential (CMAP) amplitude for tcEMEP and tcMMEP in the monkey whereas higher doses decrease the amplitude. Epidural recordings demonstrate a marked increase in the number of I waves consistent with a cortical effect similar to the postulated effect that results in

  8. The effect of a concurrent cognitive task on cortical potentials evoked by unpredictable balance perturbations

    Directory of Open Access Journals (Sweden)

    Staines W Richard

    2004-05-01

    Full Text Available Abstract Background Although previous studies suggest that postural control requires attention and other cognitive resources, the central mechanisms responsible for this relationship remain unclear. To address this issue, we examined the effects of altered attention on cortical activity and postural responses following mechanical perturbations to upright stance. We hypothesized that cortical activity would be attenuated but not delayed when mechanical perturbations were applied during a concurrent performance of a cognitive task (i.e. when attention was directed away from the perturbation. We also hypothesized that these cortical changes would be accompanied by alterations in the postural response, as evidenced by increases in the magnitude of anteroposterior (AP centre of pressure (COP peak displacements and tibialis anterior (TA muscle activity. Healthy young adults (n = 7 were instructed to continuously track (cognitive task or not track (control task a randomly moving visual target using a hand-held joystick. During each of these conditions, unpredictable translations of a moving floor evoked cortical and postural responses. Scalp-recorded cortical activity, COP, and TA electromyographic (EMG measures were collected. Results Results revealed a significant decrease in the magnitude of early cortical activity (the N1 response, the first negative peak after perturbation onset during the tracking task compared to the control condition. More pronounced AP COP peak displacements and EMG magnitudes were also observed for the tracking task and were possibly related to changes in the N1 response. Conclusion Based on previous notions that the N1 response represents sensory processing of the balance disturbance, we suggest that the attenuation of the N1 response is an important central mechanism that may provide insight into the relationship between attention and postural control.

  9. Clinical and instrumental (magnetic resonance imaging [MRI] and multimodal evoked potentials) follow-up of brain lesions in three young patients with neurofibromatosis 1.

    Science.gov (United States)

    Margari, Lucia; Presicci, Anna; Ventura, Patrizia; Maria Bacca, Simona; Iliceto, Gianni; Medicamento, Nicola; Buttiglione, Maura; Perniola, Tommaso

    2006-12-01

    Diagnosis of neurofibromatosis 1 is based on clinical criteria. In a large number of children with neurofibromatosis 1, magnetic resonance imaging (MRI) reveals high-signal T(2)-weighted intensities in different brain regions, defined as unidentified bright objects. These lesions are asymptomatic; most of them regress spontaneously with age, but the presence of contrast enhancement or mass effect in them usually strongly suggests an increased risk of proliferative changes. To date, few studies have focused on evoked potentials in patients with neurofibromatosis 1, and the reported abnormalities did not have significant clinical correlations. We describe the clinical and instrumental (MRI and evoked potentials) follow-up of three patients with neurofibromatosis 1. MRI and evoked potentials showed subclinical involvement of the central nervous system. Some MRI T(2)-weighted hyperintensities showed enhancement and mass effect of uncertain significance. During follow-up, the MRI lesions spontaneously decreased in size or enhancement, allowing us to exclude the hypothesis of proliferative lesions; in the same way, some asymptomatic evoked potential abnormalities disappeared. These findings suggest that both MRI and evoked potentials could be useful in the detection and monitoring of cerebral complications of neurofibromatosis 1.

  10. Early and late activity in somatosensory cortex reflects changes in bodily self-consciousness: an evoked potential study.

    Science.gov (United States)

    Aspell, J E; Palluel, E; Blanke, O

    2012-08-02

    How can we investigate the brain mechanisms underlying self-consciousness? Recent behavioural studies on multisensory bodily perception have shown that multisensory conflicts can alter bodily self-consciousness such as in the "full body illusion" (FBI) in which changes in self-identification with a virtual body and tactile perception are induced. Here we investigated whether experimental changes in self-identification during the FBI are accompanied by activity changes in somatosensory cortex by recording somatosensory-evoked potentials (SEPs). To modulate self-identification, participants were filmed by a video camera from behind while their backs were stroked, either synchronously (illusion condition) or asynchronously (control condition) with respect to the stroking seen on their virtual body. Tibial nerve SEPs were recorded during the FBI and analysed using evoked potential (EP) mapping. Tactile mislocalisation was measured using the crossmodal congruency task. SEP mapping revealed five sequential periods of brain activation during the FBI, of which two differed between the illusion condition and the control condition. Activation at 30-50 ms (corresponding to the P40 component) in primary somatosensory cortex was stronger in the illusion condition. A later activation at ∼110-200 ms, likely originating in higher-tier somatosensory regions in parietal cortex, was stronger and lasted longer in the control condition. These data show that changes in bodily self-consciousness modulate activity in primary and higher-tier somatosensory cortex at two distinct processing steps. We argue that early modulations of primary somatosensory cortex may be a consequence of (1) multisensory integration of synchronous vs. asynchronous visuo-tactile stimuli and/or (2) differences in spatial attention (to near or far space) between the conditions. The later activation in higher-tier parietal cortex (and potentially other regions in temporo-parietal and frontal cortex) likely

  11. Auditory- and Vestibular-Evoked Potentials Correlate with Motor and Non-Motor Features of Parkinson’s Disease

    Science.gov (United States)

    Shalash, Ali Soliman; Hassan, Dalia Mohamed; Elrassas, Hanan Hani; Salama, Mohamed Mosaad; Méndez-Hernández, Edna; Salas-Pacheco, José M.; Arias-Carrión, Oscar

    2017-01-01

    Degeneration of several brainstem nuclei has been long related to motor and non-motor symptoms (NMSs) of Parkinson’s disease (PD). Nevertheless, due to technical issues, there are only a few studies that correlate that association. Brainstem auditory-evoked potential (BAEP) and vestibular-evoked myogenic potential (VEMP) responses represent a valuable tool for brainstem assessment. Here, we investigated the abnormalities of BAEPs, ocular VEMPs (oVEMPs), and cervical VEMPs (cVEMPs) in patients with PD and its correlation to the motor and NMSs. Fifteen patients diagnosed as idiopathic PD were evaluated by Unified Parkinson’s Disease Rating Scale and its subscores, Hoehn and Yahr scale, Schwab and England scale, and Non-Motor Symptoms Scale. PD patients underwent pure-tone, speech audiometry, tympanometry, BAEP, oVEMPs, and cVEMPs, and compared to 15 age-matched control subjects. PD subjects showed abnormal BAEP wave morphology, prolonged absolute latencies of wave V and I–V interpeak latencies. Absent responses were the marked abnormality seen in oVEMP. Prolonged latencies with reduced amplitudes were seen in cVEMP responses. Rigidity and bradykinesia were correlated to the BAEP and cVEMP responses contralateral to the clinically more affected side. Contralateral and ipsilateral cVEMPs were significantly correlated to sleep (p = 0.03 and 0.001), perception (p = 0.03), memory/cognition (p = 0.025), and urinary scores (p = 0.03). The oVEMP responses showed significant correlations to cardiovascular (p = 0.01) and sexual dysfunctions (p = 0.013). PD is associated with BAEP and VEMP abnormalities that are correlated to the motor and some non-motor clinical characteristics. These abnormalities could be considered as potential electrophysiological biomarkers for brainstem dysfunction and its associated motor and non-motor features. PMID:28289399

  12. Effects of external trigeminal nerve stimulation (eTNS) on laser evoked cortical potentials (LEP): A pilot study in migraine patients and controls.

    Science.gov (United States)

    Vecchio, Eleonora; Gentile, Eleonora; Franco, Giovanni; Ricci, Katia; de Tommaso, Marina

    2017-01-01

    Background Transcutaneous external supraorbital nerve stimulation has emerged as a treatment option for primary headache disorders, though its action mechanism is still unclear. Study aim In this randomized, sham-controlled pilot study we aimed to test the effects of a single external transcutaneous nerve stimulation session on pain perception and cortical responses induced by painful laser stimuli delivered to the right forehead and the right hand in a cohort of migraine without aura patients and healthy controls. Methods Seventeen migraine without aura patients and 21 age- and sex-matched controls were selected and randomly assigned to a real or sham external transcutaneous nerve stimulation single stimulation session. The external transcutaneous nerve stimulation was delivered with a self-adhesive electrode placed on the forehead and generating a 60 Hz pulse at 16 mA intensity for 20 minutes. For sham stimulation, we used 2 mA intensity. Laser evoked responses were recorded from 21 scalp electrodes in basal condition (T0), during external transcutaneous nerve stimulation and sham stimulation (T1), and immediately after these (T2). The laser evoked responses were analyzed by LORETA software. Results The real external transcutaneous nerve stimulation reduced the trigeminal N2P2 amplitude in migraine and control groups significantly in respect to placebo. The real stimulation was associated with lower activity in the anterior cingulate cortex under trigeminal laser stimuli. The pattern of LEP-reduced habituation was reverted by real and sham transcutaneous stimulation in migraine patients. Conclusions The present results could suggest that the external transcutaneous nerve stimulation may interfere with the threshold and the extent of trigeminal system activation, with a mechanism of potential utility in the resolution and prevention of migraine attacks.

  13. Pain Processing and Vegetative Dysfunction in Fibromyalgia: A Study by Sympathetic Skin Response and Laser Evoked Potentials

    Directory of Open Access Journals (Sweden)

    Marina de Tommaso

    2017-01-01

    Full Text Available Background. A dysfunction of pain processing at central and peripheral levels was reported in fibromyalgia (FM. We aimed to correlate laser evoked potentials (LEPs, Sympathetic Skin Response (SSR, and clinical features in FM patients. Methods. Fifty FM patients and 30 age-matched controls underwent LEPs and SSR by the right hand and foot. The clinical evaluation included FM disability (FIQ and severity scores (WPI, anxiety (SAS and depression (SDS scales, and questionnaires for neuropathic pain (DN4. Results. The LEP P2 latency and amplitude and the SSR latency were increased in FM group. This latter feature was more evident in anxious patients. The LEPs habituation was reduced in FM patients and correlated to pain severity scores. In a significant number of patients (32% with higher DN4 and FIQ scores, SSR or LEP responses were absent. Conclusions. LEPs and SSR might contribute to clarifying the peripheral and central nervous system involvement in FM patients.

  14. The correlation between evoked spinal cord potentials and magnetic resonance imaging before Surgery in cervical spondylotic myelopathy

    International Nuclear Information System (INIS)

    Akashi, Kosuke; Kanchiku, Tsukasa; Taguchi, Toshihiko; Kato, Yoshihiko; Imajo, Yasuaki; Suzuki, Hidenori

    2010-01-01

    The purpose of this study is to clarify the correlation between electrophysiological examination and MRI diagnosis. Twenty-four patients with cervical spondylotic myelopathy were examined with magnetic resonance imaging and evoked spinal cord potentials (ESCPs) before surgery. In all the patients, only the intervertebral level was symptomatic, as shown by ESCPs. ESCPs following median nerve stimulation (MN-ESCPs), transcranial electric stimulation (TCE-ESCPs), and spinal cord stimulation (Spinal-ECSPs) were recorded. The patients were grouped into two groups as follows: group A, all ESCPs were abnormal; group B, normal spinal cord stimulation. Spinal cord transverse area and compression ratio (central and 1/4-lateral anteroposterior diameter divided by transverse diameter) were measured on T1-weighted axial imaging, with abnormal ESCPs as indicators of spinal cord morphology. Central and 1/4-lateral compression ratio was significantly lower in group A. Spinal cord morphology of magnetic resonance imaging is useful for functional diagnosis. (author)

  15. Significance of Visual Evoked Potentials in the Assessment of Visual Field Defects in Primary Open-Angle Glaucoma: A Review

    Directory of Open Access Journals (Sweden)

    Ruchi Kothari

    2013-01-01

    Full Text Available Visual evoked potentials is an important visual electrophysiological tool which has been used for the evaluation of visual field defects in primary open-angle glaucoma and is an appropriate objective measure of optic nerve function. Significant correlations between the magnitude of the VEP parameters and MD of Humphrey static perimetry suggest that the impaired visual cortical responses observed in glaucoma patients can be revealed by both electrophysiological and psychophysical methods. In addition, the severity of global glaucomatous damage evidenced by reduction in MD could depend on the delay in neural conduction from retina to the visual cortex as revealed by the significant correlation between VEP latencies and MD which also supports the validity of the VEP testing in progression of glaucoma.

  16. Comparison of clinical, magnetic resonance and evoked potentials data in a case of valproic-acid-related hyperammonemic coma

    Energy Technology Data Exchange (ETDEWEB)

    Hantson, Philippe [Universite Catholique de Louvain, Department of Intensive Care, Cliniques Saint-Luc, Brussels (Belgium); Grandin, Cecile; Duprez, Thierry [Universite Catholique de Louvain, Department of Neuroradiology, Cliniques Saint-Luc, Brussels (Belgium); Nassogne, Marie-Cecile [Universite Catholique de Louvain, Department of Pediatric Neurology, Cliniques Saint-Luc, Brussels (Belgium); Guerit, Jean-Michel [Universite Catholique de Louvain, Laboratory of Neurophysiology, Cliniques Saint-Luc, Brussels (Belgium)

    2005-01-01

    Magnetic resonance (MR) multimodality evoked potentials (MEPs) and clinical findings were correlated in a 47-year-old epileptic man in whom parenteral valproic acid (VPA) therapy induced severe comatose hyperammonemic encephalopathy without biological signs of hepatotoxicity (or hepatocytic dysfunction). Although the plasma VPA level remained within a normal therapeutic range, the ammoniemia increased to a toxic peak level at 411 {mu}mol/l 24 h after symptom onset, requiring VPA therapy discontinuation. Brain MR monitoring demonstrated early cytotoxic edema evolving into delayed vasogenic edema and final brain atrophy. Concomitantly to abnormalities within the brainstem on MR images, an increase in brainstem conduction at MEPs and clinical disturbance of brainstem reflexes were observed at the initial phase of the disease course. Later, the resolution of the MR and MEPs abnormalities paralleled the clinical recovery of the reflexes. (orig.)

  17. Motor-Evoked Potential Confirmation of Functional Improvement by Transplanted Bone Marrow Mesenchymal Stem Cell in the Ischemic Rat Brain

    Science.gov (United States)

    Jang, Dong-Kyu; Park, Sang-In; Han, Young-Min; Jang, Kyung-Sool; Park, Moon-Seo; Chung, Young-An; Kim, Min-Wook; Maeng, Lee-So; Huh, Pil-Woo; Yoo, Do-Sung; Jung, Seong-Whan

    2011-01-01

    This study investigated the effect of bone marrow mesenchymal stem cells (BMSCs) on the motor pathway in the transient ischemic rat brain that were transplanted through the carotid artery, measuring motor-evoked potential (MEP) in the four limbs muscle and the atlantooccipital membrane, which was elicited after monopolar and bipolar transcortical stimulation. After monopolar stimulation, the latency of MEP was significantly prolonged, and the amplitude was less reduced in the BMSC group in comparison with the control group (P < .05). MEPs induced by bipolar stimulation in the left forelimb could be measured in 40% of the BMSC group and the I wave that was not detected in the control group was also detected in 40% of the BMSC group. Our preliminary results imply that BMSCs transplanted to the ischemic rat brain mediate effects on the functional recovery of the cerebral motor cortex and the motor pathway. PMID:21772790

  18. Motor-Evoked Potential Confirmation of Functional Improvement by Transplanted Bone Marrow Mesenchymal Stem Cell in the Ischemic Rat Brain

    Directory of Open Access Journals (Sweden)

    Dong-Kyu Jang

    2011-01-01

    Full Text Available This study investigated the effect of bone marrow mesenchymal stem cells (BMSCs on the motor pathway in the transient ischemic rat brain that were transplanted through the carotid artery, measuring motor-evoked potential (MEP in the four limbs muscle and the atlantooccipital membrane, which was elicited after monopolar and bipolar transcortical stimulation. After monopolar stimulation, the latency of MEP was significantly prolonged, and the amplitude was less reduced in the BMSC group in comparison with the control group (<.05. MEPs induced by bipolar stimulation in the left forelimb could be measured in 40% of the BMSC group and the I wave that was not detected in the control group was also detected in 40% of the BMSC group. Our preliminary results imply that BMSCs transplanted to the ischemic rat brain mediate effects on the functional recovery of the cerebral motor cortex and the motor pathway.

  19. Steady-state visual evoked potentials as a research tool in social affective neuroscience

    OpenAIRE

    Wieser, Matthias J.; Miskovic, Vladimir; Keil, Andreas

    2016-01-01

    Like many other primates, humans place a high premium on social information transmission and processing. One important aspect of this information concerns the emotional state of other individuals, conveyed by distinct visual cues such as facial expressions, overt actions, or by cues extracted from the situational context. A rich body of theoretical and empirical work has demonstrated that these socio-emotional cues are processed by the human visual system in a prioritized fashion, in the serv...

  20. Bypass or not? Adjustment of surgical strategies according to motor evoked potential changes in large middle cerebral artery aneurysm surgery.

    Science.gov (United States)

    Chen, Liang; Lang, Liqin; Zhou, Liangfu; Song, Donglei; Mao, Ying

    2012-02-01

    To report the use of neuroelectrophysiologic monitoring to alter the course in aneurysm surgery to minimize postoperative infarction and bypass-related adverse events. Two patients with large middle cerebral artery (MCA) aneurysms were admitted to the authors' hospital. Direct clipping seemed to be difficult, and postoperative paralysis was not rare in the authors' experience owing to prolonged temporal occlusion of the parent artery. Balloon test occlusion (BTO) was positive in one patient, who developed paralysis and aphasia 3 minutes after balloon occlusion of the feeding M1 artery. A bypass procedure seemed to be inevitable in both patients. Motor evoked potentials (MEPs) and sensory evoked potentials (SEPs) were used for monitoring during the operation. For the patient with a positive BTO result, MEP waves did not change until 17 minutes after temporary clip placement. The aneurysm was clipped, and the occlusion time was 24 minutes. MEP waves recovered quickly after reperfusion. In the other patient, there were early changes in MEP waves after temporary clipping. After bypass construction from the temporal artery to the inferior M2 trunk, the time window of safe occlusion was prolonged to 7-8 minutes. Both the aneurysm and the bypassed branch were obliterated, and the clip reconstruction was done to preserve the flow from M1 to the superior M2 trunk. Permanent postoperative disability did not occur in either patient. Intraoperative physiologic monitoring is a complementary method to preoperative BTO to evaluate the window of safe occlusion with high reliability. Copyright © 2012 Elsevier Inc. All rights reserved.

  1. Flash visual evoked potentials in patients with periventricular leucomalacia in children less than 1 year of age.

    Science.gov (United States)

    Jethani, Jitendra; Jethani, Monika

    2013-11-01

    Children with periventricular leucomalacia (PVL) are known to have visual impairment of various forms starting from reduced vision, field defects, congnitive problems, and problems with hand eye coordination. There is very scant data/literature on the visual evoked potentials (VEPs) at an early age in children with PVL. We did a study to evaluate the flash visual evoked potentials (fVEPs) in children with PVL less than 1 year of age. A total of nine children diagnosed as having PVL on magnetic resonance imaging were included in the study. The mean age was 9.7μ 3.5 months. All children underwent handheld fVEPs under sedation at two different flash frequencies 1.4 and 8 Hz. The mean latency of N1 and P1 on stimulation with 1.4 Hz was 47.9μ 15.2 and 77.7μ 26.0 ms, respectively. However, on stimulation with 8 Hz the mean latency of N1 and P1 was 189.8μ 25.6 and 238.4μ 33.6 ms, respectively. The mean amplitude with 1.4 Hz and 8 stimulation frequency was 5.6μ 4.5 and 5.59μ 3 mV, respectively. We have found for the first time that there is a change in the latency and the delay occurs at 8 Hz frequency but not at 1.4 Hz. We also conclude that amplitudes by fVEPs may be normal even in presence of periventricular changes. The amplitudes of fVEPs are not reliable in children with PVL.

  2. Flash visual evoked potentials in patients with periventricular leucomalacia in children less than 1 year of age

    Directory of Open Access Journals (Sweden)

    Jitendra Jethani

    2013-01-01

    Full Text Available Background and Aim: Children with periventricular leucomalacia (PVL are known to have visual impairment of various forms starting from reduced vision, field defects, congnitive problems, and problems with hand eye coordination. There is very scant data/literature on the visual evoked potentials (VEPs at an early age in children with PVL. We did a study to evaluate the flash visual evoked potentials (fVEPs in children with PVL less than 1 year of age. Materials and Methods: A total of nine children diagnosed as having PVL on magnetic resonance imaging were included in the study. The mean age was 9.7μ 3.5 months. All children underwent handheld fVEPs under sedation at two different flash frequencies 1.4 and 8 Hz. Results: The mean latency of N1 and P1 on stimulation with 1.4 Hz was 47.9μ 15.2 and 77.7μ 26.0 ms, respectively. However, on stimulation with 8 Hz the mean latency of N1 and P1 was 189.8μ 25.6 and 238.4μ 33.6 ms, respectively. The mean amplitude with 1.4 Hz and 8 stimulation frequency was 5.6μ 4.5 and 5.59μ 3 mV, respectively. Conclusion: We have found for the first time that there is a change in the latency and the delay occurs at 8 Hz frequency but not at 1.4 Hz. We also conclude that amplitudes by fVEPs may be normal even in presence of periventricular changes. The amplitudes of fVEPs are not reliable in children with PVL.

  3. Resting state in Alzheimer's disease: a concurrent analysis of Flash-Visual Evoked Potentials and quantitative EEG

    Directory of Open Access Journals (Sweden)

    Tartaglione Antonio

    2012-11-01

    Full Text Available Abstract Background To investigate to what extent Alzheimer's Disease (AD affects Resting State activity, the possible impairment of independent electrophysiological parameters was determined in Eye-open and Eye-closed Conditions. Specifically, Flash-Visual Evoked Potential (F-VEP and quantitative EEG (q-EEG were examined to establish whether abnormalities of the former were systematically associated with changes of the latter. Methods Concurrently recorded F-VEP and q-EEG were comparatively analysed under Eye-open and Eye-closed Conditions in 11 Controls and 19 AD patients presenting a normal Pattern-Visual Evoked Potential (P-VEP. Between Condition differences in latencies of P2 component were matched to variations in spectral components of q-EEG. Results P2 latency increased in 10 AD patients with Abnormal Latency (AD-AL under Eye-closed Condition. In these patients reduction of alpha activity joined an increased delta power so that their spectral profile equated that recorded under Eye-open Condition. On the opposite, in Controls as well as in AD patients with Normal P2 Latency (AD-NL spectral profiles recorded under Eye-open and Eye-closed Conditions significantly differed from each other. At the baseline, under Eye-open Condition, the spectra overlapped each other in the three Groups. Conclusion Under Eye-closed Condition AD patients may present a significant change in both F-VEP latency and EEG rhythm modulation. The presence of concurrent changes of independent parameters suggests that the neurodegenerative process can impair a control system active in Eye-closed Condition which the electrophysiological parameters depend upon. F-VEP can be viewed as a reliable marker of such impairment.

  4. A new method for registration of kinesthetic evoked potentials for studies of proprioceptive sensitivity in normal subjects and patients with organic lesions in the brain.

    Science.gov (United States)

    Gordeev, S A; Voronin, S G

    2015-01-01

    The proprioceptive sensitivity of healthy volunteers and convalescents after acute cerebrovascular episodes was studied by a new neurophysiological method for registration of kinesthetic evoked potentials emerging in response to passive 50(o) bending of the hand in the wrist joint with the angular acceleration of 350 rad/sec(2). Kinesthetic evoked potentials were recorded above the somatosensory cortex projection areas in the hemispheres contra- and ipsilateral to the stimulated limb. The patients exhibited significantly longer latencies and lesser amplitudes of the early components of response in the involved hemisphere in comparison with normal subjects. The method for registration of the kinesthetic evoked potentials allows a more detailed study of the mechanisms of kinesthetic sensitivity in health and in organic involvement of the brain.

  5. Is action potential threshold lowest in the axon?

    NARCIS (Netherlands)

    Kole, Maarten H. P.; Stuart, Greg J.

    2008-01-01

    Action potential threshold is thought to be lowest in the axon, but when measured using conventional techniques, we found that action potential voltage threshold of rat cortical pyramidal neurons was higher in the axon than at other neuronal locations. In contrast, both current threshold and voltage

  6. Re-modeling Chara action potential: II. The action potential form under salinity stress

    Directory of Open Access Journals (Sweden)

    Mary Jane Beilby

    2017-04-01

    Full Text Available In part I we established Thiel-Beilby model of the Chara action potential (AP. In part II the AP is investigated in detail at the time of saline stress. Even very short exposure of salt-sensitive Chara cells to artificial pond water with 50 mM NaCl (Saline APW modified the AP threshold and drastically altered the AP form. Detailed modeling of 14 saline APs from 3 cells established that both the Ca2+ pump and the Ca2+ channels on internal stores seem to be affected, with the changes sometimes cancelling and sometimes re-enforcing each other, leading to APs with long durations and very complex forms. The exposure to salinity offers further insights into AP mechanism and suggests future experiments. The prolonged APs lead to greater loss of chloride and potassium ions, compounding the effects of saline stress.

  7. Dynamic Action Potential Restitution Contributes to Mechanical Restitution in Right Ventricular Myocytes From Pulmonary Hypertensive Rats.

    Science.gov (United States)

    Hardy, Matthew E L; Pervolaraki, Eleftheria; Bernus, Olivier; White, Ed

    2018-01-01

    We investigated the steepened dynamic action potential duration (APD) restitution of rats with pulmonary artery hypertension (PAH) and right ventricular (RV) failure and tested whether the observed APD restitution properties were responsible for negative mechanical restitution in these myocytes. PAH and RV failure were provoked in male Wistar rats by a single injection of monocrotaline (MCT) and compared with saline-injected animals (CON). Action potentials were recorded from isolated RV myocytes at stimulation frequencies between 1 and 9 Hz. Action potential waveforms recorded at 1 Hz were used as voltage clamp profiles (action potential clamp) at stimulation frequencies between 1 and 7 Hz to evoke rate-dependent currents. Voltage clamp profiles mimicking typical CON and MCT APD restitution were applied and cell shortening simultaneously monitored. Compared with CON myocytes, MCT myocytes were hypertrophied; had less polarized diastolic membrane potentials; had action potentials that were triggered by decreased positive current density and shortened by decreased negative current density; APD was longer and APD restitution steeper. APD90 restitution was unchanged by exposure to the late Na + -channel blocker (5 μM) ranolazine or the intracellular Ca 2+ buffer BAPTA. Under AP clamp, stimulation frequency-dependent inward currents were smaller in MCT myocytes and were abolished by BAPTA. In MCT myocytes, increasing stimulation frequency decreased contraction amplitude when depolarization duration was shortened, to mimic APD restitution, but not when depolarization duration was maintained. We present new evidence that the membrane potential of PAH myocytes is less stable than normal myocytes, being more easily perturbed by external currents. These observations can explain increased susceptibility to arrhythmias. We also present novel evidence that negative APD restitution is at least in part responsible for the negative mechanical restitution in PAH myocytes. Thus

  8. Comparison of auditory evoked potentials and the A-line ARX Index for monitoring the hypnotic level during sevoflurane and propofol induction

    DEFF Research Database (Denmark)

    Litvan, H; Jensen, E W; Revuelta, M

    2002-01-01

    Extraction of the middle latency auditory evoked potentials (AEP) by an auto regressive model with exogenous input (ARX) enables extraction of the AEP within 1.7 s. In this way, the depth of hypnosis can be monitored at almost real-time. However, the identification and the interpretation of the a......Extraction of the middle latency auditory evoked potentials (AEP) by an auto regressive model with exogenous input (ARX) enables extraction of the AEP within 1.7 s. In this way, the depth of hypnosis can be monitored at almost real-time. However, the identification and the interpretation...

  9. A new vision on the averaging technique for the estimation of non-stationary Brainstem Auditory-Evoked Potentials: application of a metaheuristic method.

    Science.gov (United States)

    Naït-Ali, Amine; Siarry, Patrick

    2006-06-01

    The aim of this paper consists in highlighting the use of the averaging technique in some biomedical applications, such as evoked potentials (EP) extraction. We show that this technique, which is generally considered as classical, can be very efficient if the dynamic model of the signal to be estimated is a priori known. Therefore, using an appropriate model and under some specific conditions, one can show that the estimation can be performed efficiently even in case of a very low signal to noise ratio (SNR), which occurs when handling Brainstem Auditory-Evoked Potentials.

  10. Repetition suppression in transcranial magnetic stimulation-induced motor-evoked potentials is modulated by cortical inhibition.

    Science.gov (United States)

    Kallioniemi, E; Pääkkönen, A; Julkunen, P

    2015-12-03

    Transcranial magnetic stimulation (TMS) can be applied to modulate cortical phenomena. The modulation effect is dependent on the applied stimulation frequency. Repetition suppression (RS) has been demonstrated in the motor system using TMS with short suprathreshold 1-Hz stimulation trains repeated at long inter-train intervals. RS has been reported to occur in the resting motor-evoked potentials (MEPs) with respect to the first pulse in a train of stimuli. Although this RS in the motor system has been described in previous studies, the neuronal origin of the phenomenon is still poorly understood. The present study evaluated RS in three TMS-induced motor responses; resting and active MEPs as well as corticospinal silent periods (SPs) in order to clarify the mechanism behind TMS-induced RS. We studied 10 healthy right-handed subjects using trains of four stimuli with stimulation intensities of 120% of the resting motor threshold (rMT) and 120% of the silent period threshold for an SP duration of 30 ms (SPT30). Inter-trial interval was 20s, with a 1-s inter-stimulus interval within the trains. We confirmed that RS appears in resting MEPs (p 0.792). SPs, on the contrary, lengthened (p < 0.001) indicating modulation of cortical inhibition. The effects of the two stimulation intensities exhibited a similar trend; however, the SPT30 evoked a more profound inhibitory effect compared to that achieved by rMT. Moreover, the resting MEP amplitudes and SP durations correlated (rho ⩽ -0.674, p < 0.001) and the pre-TMS EMG level did not differ between stimuli in resting MEPs (F = 0.0, p ⩾ 0.999). These results imply that the attenuation of response size seen in resting MEPs might originate from increasing activity of inhibitory GABAergic interneurons which relay the characteristics of SPs. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

  11. Chiasmal coefficient of flash and pattern visual evoked potentials for detection of chiasmal misrouting in albinism

    NARCIS (Netherlands)

    Pott, JWR; Jansonius, NM; Kooijman, AC

    The diagnosis of albinism can be confirmed by electrophysiological examination, when chiasmal misrouting can be demonstrated. The present study describes a quantitative analysis method for this purpose. A chiasmal coefficient (CC) was calculated by correlating the differential potential over left

  12. Effects of glutamate receptor agonists on the P13 auditory evoked potential and startle response in the rat

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    Christen eSimon

    2011-01-01

    Full Text Available The P13 potential is the rodent equivalent of the P50 potential, which is an evoked response recorded at the vertex (Vx 50 msec following an auditory stimulus in humans. Both the P13 and P50 potentials are only present during waking and rapid eye movement (REM sleep, and are considered to be measures of level of arousal. The source of the P13 and P50 potentials appears to be the pedunculopontine nucleus (PPN, a brainstem nucleus with indirect ascending projections to the cortex through the intralaminar thalamus (ILT, mediating arousal, and descending inhibitory projections to the caudal pontine reticular formation (CPRF, which mediates the auditory startle response (SR. We tested the hypothesis that intracranial microinjection (ICM of glutamate (GLU or GLU receptor agonists will increase the activity of PPN neurons, resulting in an increased P13 potential response, and decreased SR due to inhibitory projections from the PPN to the CPRF, in freely moving animals. Cannulae were inserted into the PPN to inject neuroactive agents, screws were inserted into the Vx in order to record the P13 potential, and electrodes inserted into the dorsal nuchal muscle to record electromyograms (EMGs and SR amplitude. Our results showed that ICM of GLU into the PPN dose-dependently increased the amplitude of the P13 potential and decreased the amplitude of the SR. Similarly, ICM of NMDA or KA into the PPN increased the amplitude of the P13 potential. These findings indicate that glutamatergic input to the PPN plays a role in arousal control in vivo, and changes in glutamatergic input, or excitability of PPN neurons, could be implicated in a number of neuropsychiatric disorders with the common symptoms of hyperarousal and REM sleep dysregulation.

  13. Action potential propagation: ion current or intramembrane electric field?

    Science.gov (United States)

    Martí, Albert; Pérez, Juan J; Madrenas, Jordi

    2018-01-01

    The established action potential propagation mechanisms do not satisfactorily explain propagation on myelinated axons given the current knowledge of biological channels and membranes. The flow across ion channels presents two possible effects: the electric potential variations across the lipid bilayers (action potential) and the propagation of an electric field through the membrane inner part. The proposed mechanism is based on intra-membrane electric field propagation, this propagation can explain the action potential saltatory propagation and its constant delay independent of distance between Ranvier nodes in myelinated axons.

  14. TACTILE STIMULATION EVOKES LONG-LASTING POTENTIATION OF PURKINJE CELL DISCHARGE IN VIVO

    Directory of Open Access Journals (Sweden)

    Ramakrishnan eKanchipuram

    2016-02-01

    Full Text Available In the cerebellar network, a precise relationship between plasticity and neuronal discharge has been predicted. However, the potential generation of persistent changes in PC spike discharge as a consequence of plasticity following natural stimulation patterns has not been clearly determined. Here we show that facial tactile stimuli organized in theta-patterns can induce stereotyped NMDA and GABA-A receptor-dependent changes in Purkinje cell (PCs and molecular layer interneuron (MLIs firing: invariably, all PCs showed a long-lasting increase (spike-related potentiation or SR-P and MLIs a long-lasting decrease (spike-related suppression or SR-S in baseline activity and spike response probability. These observations suggests that natural sensory stimulation engages multiple long-term plastic changes that are distributed along the mossy fiber – parallel fiber pathway and operate synergistically to potentiate spike generation in PCs. In contrast, theta-pattern electrical stimulation of PFs indistinctly induced SR-P and SR-S both in PCs and MLIs, suggesting that natural sensory stimulation preordinates plasticity upstream of the PF-PC synapse. All these effects occurred in the absence of complex spike changes, supporting the theoretical prediction that Purkinje cell activity is potentiated when the mossy fiber - parallel fiber system is activated in the absence of conjunctive climbing fiber activity.

  15. Cortical Reorganization in Dyslexic Children after Phonological Training: Evidence from Early Evoked Potentials

    Science.gov (United States)

    Spironelli, Chiara; Penolazzi, Barbara; Vio, Claudio; Angrilli, Alessandro

    2010-01-01

    Brain plasticity was investigated in 14 Italian children affected by developmental dyslexia after 6 months of phonological training. The means used to measure language reorganization was the recognition potential, an early wave, also called N150, elicited by automatic word recognition. This component peaks over the left temporo-occipital cortex…

  16. Assessment of Human Visual Performance with a Swept Evoked Potential Technique

    Science.gov (United States)

    1984-07-01

    ment are common (leg weakness, urinary incontinence ). More recently, psychophysical studies (Regan, Silver & Murray, 1977; Regan, Whitlock, Murray...effect diminution 13. Discrete potential generations (?) 14. Strobe stimulation responses 15. Random phase EEG 16. Phase sensitive detection...latency provide an objective assessment of neural pathway conduction in the visual system. However, aspects of the electrical waveform data which can

  17. Visual Perception and Frontal Lobe in Intellectual Disabilities: A Study with Evoked Potentials and Neuropsychology

    Science.gov (United States)

    Munoz-Ruata, J.; Caro-Martinez, E.; Perez, L. Martinez; Borja, M.

    2010-01-01

    Background: Perception disorders are frequently observed in persons with intellectual disability (ID) and their influence on cognition has been discussed. The objective of this study is to clarify the mechanisms behind these alterations by analysing the visual event related potentials early component, the N1 wave, which is related to perception…

  18. Propagation of action potentials in inhomogeneous axon regions.

    Science.gov (United States)

    Ramón, F; Joyner, R W; Moore, J W

    1975-04-01

    Described are studies of propagation of action potentials through inhomogenous axon regions through experiments performed on squid giant axons and by computer simulations. The initial speed of propagation of the action potential is dependent upon the stimulus waveform. For a rectangular pulse of current, the action potential travel initally at a high speed that declines over the distance, reaching a constant speed of propagation at about 1-5 resting length constants; this distance depends on the stimulus strength. additional experiments studied the effects of changing the axon diameter and of introducing a temperature step. It was found that the propagated action potential suffers profound modification in shape and velocity as it reaches the region of transition. In both cases, it was possible to obtain reflected action potentials. A region of increased effective diameter was produced experimentally in the squid giant axon by insertion of an axial wire as usually employed in voltage clamps. It was found that the action potential, at the axial wire tip region, undergoes shape changes similar to those obtained tn simulations of a region of increased diameter as in a junction with the axon and soma in motor neurons. It is conducluded that the gaint axon can be used to reproduce simple electrical behaviors in other structures.-Ramón, F., R. W. Joyner and J.W. Moore. Propagation of action potentials in inhomogeneous axon regions.

  19. Sound-Making Actions Lead to Immediate Plastic Changes of Neuromagnetic Evoked Responses and Induced β-Band Oscillations during Perception.

    Science.gov (United States)

    Ross, Bernhard; Barat, Masihullah; Fujioka, Takako

    2017-06-14

    Auditory and sensorimotor brain areas interact during the action-perception cycle of sound making. Neurophysiological evidence of a feedforward model of the action and its outcome has been associated with attenuation of the N1 wave of auditory evoked responses elicited by self-generated sounds, such as talking and singing or playing a musical instrument. Moreover, neural oscillations at β-band frequencies have been related to predicting the sound outcome after action initiation. We hypothesized that a newly learned action-perception association would immediately modify interpretation of the sound during subsequent listening. Nineteen healthy young adults (7 female, 12 male) participated in three magnetoencephalographic recordings while first passively listening to recorded sounds of a bell ringing, then actively striking the bell with a mallet, and then again listening to recorded sounds. Auditory cortex activity showed characteristic P1-N1-P2 waves. The N1 was attenuated during sound making, while P2 responses were unchanged. In contrast, P2 became larger when listening after sound making compared with the initial naive listening. The P2 increase occurred immediately, while in previous learning-by-listening studies P2 increases occurred on a later day. Also, reactivity of β-band oscillations, as well as θ coherence between auditory and sensorimotor cortices, was stronger in the second listening block. These changes were significantly larger than those observed in control participants (eight female, five male), who triggered recorded sounds by a key press. We propose that P2 characterizes familiarity with sound objects, whereas β-band oscillation signifies involvement of the action-perception cycle, and both measures objectively indicate functional neuroplasticity in auditory perceptual learning. SIGNIFICANCE STATEMENT While suppression of auditory responses to self-generated sounds is well known, it is not clear whether the learned action-sound association

  20. Precise temporal association between cortical potentials evoked by motor imagination and afference induces cortical plasticity.

    Science.gov (United States)

    Mrachacz-Kersting, Natalie; Kristensen, Signe Rom; Niazi, Imran Khan; Farina, Dario

    2012-04-01

    In monkeys, the repeated activation of somatosensory afferents projecting onto the motor cortex (M1) has a pivotal role in motor skill learning. Here we investigate if sensory feedback that is artificially generated at specific times during imagination of a dorsiflexion task leads to reorganization of the human M1. The common peroneal nerve was stimulated to generate an afferent volley timed to arrive during specific phases of the cortical potential generated when a movement was imagined (50 repetitions). The change in the output of M1 was quantified by applying single transcranial magnetic stimuli to the area of M1 controlling the tibialis anterior muscle. The results demonstrated that the concomitance between the cognitive process of movement (motor imagination) and the ascending volley due to the peripheral nerve stimulation can lead to significant increases in cortical excitability. These increases were critically dependent on the timing between the peripherally generated afferent volley and the cortical potential generated during the imagined movement. Only if the afferent volley arrived during the peak negative deflection of the potential, were significant alterations in motor cortical output attained. These results demonstrate that an artificially generated signal (the peripheral afferent volley) can interact with a physiologically generated signal in humans leading to plastic changes within the M1, the final output stage for movement generation within the human brain. The results presented may have implications in systems for artificially inducing cortical plasticity in patients with motor impairments (neuromodulation).

  1. Voltage-gated sodium channel expression and action potential generation in differentiated NG108-15 cells.

    Science.gov (United States)

    Liu, Jinxu; Tu, Huiyin; Zhang, Dongze; Zheng, Hong; Li, Yu-Long

    2012-10-25

    The generation of action potential is required for stimulus-evoked neurotransmitter release in most neurons. Although various voltage-gated ion channels are involved in action potential production, the initiation of the action potential is mainly mediated by voltage-gated Na+ channels. In the present study, differentiation-induced changes of mRNA and protein expression of Na+ channels, Na+ currents, and cell membrane excitability were investigated in NG108-15 cells. Whole-cell patch-clamp results showed that differentiation (9 days) didn't change cell membrane excitability, compared to undifferentiated state. But differentiation (21 days) induced the action potential generation in 45.5% of NG108-15 cells (25/55 cells). In 9-day-differentiated cells, Na+ currents were mildly increased, which was also found in 21-day differentiated cells without action potential. In 21-day differentiated cells with action potential, Na+ currents were significantly enhanced. Western blot data showed that the expression of Na+ channels was increased with differentiated-time dependent manner. Single-cell real-time PCR data demonstrated that the expression of Na+ channel mRNA was increased by 21 days of differentiation in NG108-15 cells. More importantly, the mRNA level of Na+ channels in cells with action potential was higher than that in cells without action potential. Differentiation induces expression of voltage-gated Na+ channels and action potential generation in NG108-15 cells. A high level of the Na+ channel density is required for differentiation-triggered action potential generation.

  2. F-wave and motor-evoked potentials during motor imagery and observation in apraxia of Parkinson disease.

    Science.gov (United States)

    Gündüz, Ayşegül; Kiziltan, Meral E

    2015-12-01

    The amplitudes of F-waves and motor-evoked potentials (MEPs) increase during imagination or active motor performance. The aim of this study was to investigate F-wave and MEP facilitation during assessment of apraxia. Eight Parkinson disease (PD) patients with apraxia, 11 patients without apraxia, and 8 healthy volunteers were enrolled. F-waves and MEPs were recorded during 4 states (resting, imagination, observation, and active movement). The mean amplitude of the F-waves increased significantly during imagination and active movement as compared with at rest in healthy individuals (P = 0.028) and in the nonapraxia group (P = 0.005). PD patients with apraxia did not have similar facilitation. The mean amplitude of the MEPs also showed a similar loss of facilitation in PD with apraxia. Loss of facilitation during the preparation for movement is closely related to the "gold standard" clinical praxis battery. This study provides additional support and a potential electrophysiological assessment method for apraxia in PD. © 2015 Wiley Periodicals, Inc.

  3. The variability of motor evoked potential latencies in neurosurgical motor mapping by preoperative navigated transcranial magnetic stimulation.

    Science.gov (United States)

    Sollmann, Nico; Bulubas, Lucia; Tanigawa, Noriko; Zimmer, Claus; Meyer, Bernhard; Krieg, Sandro M

    2017-01-03

    Recording of motor evoked potentials (MEPs) is used during navigated transcranial magnetic stimulation (nTMS) motor mapping to locate motor function in the human brain. However, factors potentially underlying MEP latency variability in neurosurgical motor mapping are vastly unknown. In the context of this study, one hundred brain tumor patients underwent preoperative nTMS-based motor mapping of the tumor hemisphere between 2010 and 2013. Fourteen predefined predictor variables were recorded, and MEP latencies of abductor pollicis brevis muscle (APB), abductor digiti minimi muscle (ADM), and flexor carpi radialis muscle (FCR) were analyzed using linear mixed-effect multiple regression analysis with the forward step-wise model comparison approach. Common factors (relevant to APB, ADM, and FCR) for MEP latency variability were gender, most likely due to body height, and antiepileptic drug (AED) intake. Muscle-specific factors (relevant to APB, ADM, or FCR) for MEP latency variability were resting motor threshold (rMT), tumor side, and tumor location. Based on a large cohort of neurosurgical patients, this study provides data on a wide range of clinical factors that may underlie MEP latency variability. The factors that significantly contributed to MEP latency variability should be standardly recorded and taken into consideration during neurosurgical motor mapping.

  4. Increased gain of vestibulospinal potentials evoked in neck and leg muscles when standing under height-induced postural threat.

    Science.gov (United States)

    Naranjo, E N; Allum, J H J; Inglis, J T; Carpenter, M G

    2015-05-07

    To measure changes in amplitudes of vestibular evoked myogenic potentials (VEMPs) elicited from neck, upper and lower limb muscles during a quiet standing task with increased postural threat achieved by manipulating surface height. Twenty eight subjects were tested while standing on a platform raised to 0.8 m and 3.2 m from the ground. Surface electromyography was recorded from the ipsilateral sternocleidomastoid (SCM), biceps brachii (BB), flexor carpi radialis (FCR), soleus (SOL) and medial gastrocnemius (MG) muscles. Stimulation was with air-conducted short tone bursts (4 ms). After controlling for background muscle activity, VEMP amplitudes were compared between heights and correlated with changes in state anxiety, fear and arousal. VEMP amplitude significantly increased in SCM (9%) and SOL (12.7%) with increased surface height (pgains. Results demonstrate that VEMPs can be used to test different VSR pathways simultaneously during stance. Since fear and anxiety are prevalent with vestibular disorders, they should be considered as potential contributing factors for clinical vestibular outcome measures. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

  5. Central Sensitization of Mechanical Nociceptive Pathways Is Associated with a Long-Lasting Increase of Pinprick-Evoked Brain Potentials.

    Science.gov (United States)

    van den Broeke, Emanuel N; Lambert, Julien; Huang, Gan; Mouraux, André

    2016-01-01

    Intense or sustained nociceptor activation, occurring, for example, after skin injury, can induce "central sensitization," i.e., an increased responsiveness of nociceptive neurons in the central nervous system. A hallmark of central sensitization is increased mechanical pinprick sensitivity in the area surrounding the injured skin. The aim of the present study was to identify changes in brain activity related to this increased pinprick sensitivity. In 20 healthy volunteers, increased pinprick sensitivity was induced using high frequency electrical stimulation of the forearm skin (HFS). Mechanical pinprick stimulation (64 and 90 mN) was used to elicit event-related brain potentials (ERPs). The recordings were performed before, 20 min after and 45 min after applying HFS. The contralateral non-sensitized arm served as control. Pinprick stimulation of 64 mN, but not 90 mN, applied in the area of increased pinprick sensitivity elicited a significant increase of a late-latency positive wave, between 300 and 1100 ms after stimulus onset and was maximal at midline posterior electrodes. Most importantly, this increase in EEG activity followed the time course of the increase in pinprick perception, both being present 20 and 45 min after applying HFS. Our results show that the central sensitization of mechanical nociceptive pathways, manifested behaviorally as increased pinprick sensitivity, is associated with a long-lasting increase in pinprick-evoked brain potentials provided that a 64 mN stimulation intensity is used.

  6. Study of the correlation of brainstem auditory evoked potentials and magnetic resonance imaging in children with spastic cerebral palsy

    Energy Technology Data Exchange (ETDEWEB)

    Fobe, Lisete Pessoa de Oliveira [Sao Paulo Univ., SP (Brazil). Faculdade de Medicina]. E-mail: lispessoa@yahoo.com

    1999-12-01

    Central auditory evaluation in 21 children with cerebral palsy was done with brainstem auditory evoked potentials (BAEP) and correlated with brain magnetic resonance imaging findings (MRI); 12 boys and 9 girls between 5 and 12 years old were studied. All children had follow-up at the Institute of Orthopedics and Traumatology of Hospital das Clinicas da Faculdade de Medicina da Universidade de Sao Paulo. The control group was done with 17 children, 10 boys and 7 girls (mean age 8.06 years, SD 2.27 years). The BAEP abnormalities were: decrease of latency of wave V; decrease of latency III-V and I-IV intervals at the right side. All patients has MRI supratentorial abnormalities and 11 had brainstem atrophy. The MRI pathologic findings were: ventricular enlargement (n=17 or 80.95%), cortical/subcortical atrophy (n=15 or 71.42%), left brainstem atrophy (n=11 or 52.38%), periventricular leukomalacia (n=10 or 47.61%), infarction in the left middle cerebral artery territory (n=6 or 28.57%), and malformations such as schizencephaly and colpocephaly (n=5 or 23.80%). The findings of the decrease latencies in children with cerebral palsy suggest the contribution of decussating auditory fibers at the lower and upper pons and midbrain, the lack of homogeneity of the surrounding volume of the conductor fibres and the presence of several concurrently active potential generators sources, should be facilitating mechanisms for the nervous input to brainstem. (author)

  7. Study of the correlation of brainstem auditory evoked potentials and magnetic resonance imaging in children with spastic cerebral palsy

    International Nuclear Information System (INIS)

    Fobe, Lisete Pessoa de Oliveira

    1999-01-01

    Central auditory evaluation in 21 children with cerebral palsy was done with brainstem auditory evoked potentials (BAEP) and correlated with brain magnetic resonance imaging findings (MRI); 12 boys and 9 girls between 5 and 12 years old were studied. All children had follow-up at the Institute of Orthopedics and Traumatology of Hospital das Clinicas da Faculdade de Medicina da Universidade de Sao Paulo. The control group was done with 17 children, 10 boys and 7 girls (mean age 8.06 years, SD 2.27 years). The BAEP abnormalities were: decrease of latency of wave V; decrease of latency III-V and I-IV intervals at the right side. All patients has MRI supratentorial abnormalities and 11 had brainstem atrophy. The MRI pathologic findings were: ventricular enlargement (n=17 or 80.95%), cortical/subcortical atrophy (n=15 or 71.42%), left brainstem atrophy (n=11 or 52.38%), periventricular leukomalacia (n=10 or 47.61%), infarction in the left middle cerebral artery territory (n=6 or 28.57%), and malformations such as schizencephaly and colpocephaly (n=5 or 23.80%). The findings of the decrease latencies in children with cerebral palsy suggest the contribution of decussating auditory fibers at the lower and upper pons and midbrain, the lack of homogeneity of the surrounding volume of the conductor fibres and the presence of several concurrently active potential generators sources, should be facilitating mechanisms for the nervous input to brainstem. (author)

  8. Connectopathy in Autism Spectrum Disorders: A Review of Evidence from Visual Evoked Potentials and Diffusion Magnetic Resonance Imaging

    Directory of Open Access Journals (Sweden)

    Takao Yamasaki

    2017-11-01

    Full Text Available Individuals with autism spectrum disorder (ASD show superior performance in processing fine details; however, they often exhibit impairments of gestalt face, global motion perception, and visual attention as well as core social deficits. Increasing evidence has suggested that social deficits in ASD arise from abnormal functional and structural connectivities between and within distributed cortical networks that are recruited during social information processing. Because the human visual system is characterized by a set of parallel, hierarchical, multistage network systems, we hypothesized that the altered connectivity of visual networks contributes to social cognition impairment in ASD. In the present review, we focused on studies of altered connectivity of visual and attention networks in ASD using visual evoked potentials (VEPs, event-related potentials (ERPs, and diffusion tensor imaging (DTI. A series of VEP, ERP, and DTI studies conducted in our laboratory have demonstrated complex alterations (impairment and enhancement of visual and attention networks in ASD. Recent data have suggested that the atypical visual perception observed in ASD is caused by altered connectivity within parallel visual pathways and attention networks, thereby contributing to the impaired social communication observed in ASD. Therefore, we conclude that the underlying pathophysiological mechanism of ASD constitutes a “connectopathy.”

  9. Connectopathy in Autism Spectrum Disorders: A Review of Evidence from Visual Evoked Potentials and Diffusion Magnetic Resonance Imaging.

    Science.gov (United States)

    Yamasaki, Takao; Maekawa, Toshihiko; Fujita, Takako; Tobimatsu, Shozo

    2017-01-01

    Individuals with autism spectrum disorder (ASD) show superior performance in processing fine details; however, they often exhibit impairments of gestalt face, global motion perception, and visual attention as well as core social deficits. Increasing evidence has suggested that social deficits in ASD arise from abnormal functional and structural connectivities between and within distributed cortical networks that are recruited during social information processing. Because the human visual system is characterized by a set of parallel, hierarchical, multistage network systems, we hypothesized that the altered connectivity of visual networks contributes to social cognition impairment in ASD. In the present review, we focused on studies of altered connectivity of visual and attention networks in ASD using visual evoked potentials (VEPs), event-related potentials (ERPs), and diffusion tensor imaging (DTI). A series of VEP, ERP, and DTI studies conducted in our laboratory have demonstrated complex alterations (impairment and enhancement) of visual and attention networks in ASD. Recent data have suggested that the atypical visual perception observed in ASD is caused by altered connectivity within parallel visual pathways and attention networks, thereby contributing to the impaired social communication observed in ASD. Therefore, we conclude that the underlying pathophysiological mechanism of ASD constitutes a "connectopathy."

  10. [Monitoring of somatosensory evoked potentials during surgery for aneurysms of the sylvian artery].

    Science.gov (United States)

    Lazorthes, Y; Sonilhac, F; Lagarrigue, J; Scavazza, R

    1992-01-01

    Per-operative use of S.E.P.s for vascular disease is based on: 1. The relationship between electrical cortical responses and cerebral blood flow. 2. The existence of a reversible threshold of cerebral ischemia. Intra-operative monitoring S.E.P.s were used during 30 procedures for aneurysms of the middle cerebral artery (M.C.A.). In 18 cases, a temporary occlusion of M.C.A. was necessary. Occlusion times ranged from 1 to 30 minutes. The central conduction time delay (C.C.T.), i.e. the delay N14-N20 and the cortical peak (N20) amplitude, elicited by median nerve stimulation was bilaterally monitored. A prolongation of the C.C.T. by 1 millisecond (compared with the baseline induction value) and a progressive decrease or a disappearance of the N20 peak were considered as "significant" changes. In response to these changes, immediate corrective actions (interruption of temporary M.C.A. occlusion (T.O.), repositioning of brain retractors, reapplication of aneurysm clips ...) were implemented. The reversibility of the S.E.P.s alterations during surgery was correlated with the post-operative outcome. Significant changes were found in 20 cases (including 13 T.O.). They were totally reversible in 11 cases: 5 of them developed a new but transient immediate post-operative deficit, none had a definitive deficit, and 6 patients had no new deficit. In 9 cases, the per-operative S.E.P.s alterations were not reversible: 3 cases (including 1 T.O.) had a transient deficit, 4 a permanent deficit, and 1 died (aneurysm rupture during craniotomy). An irreversible N20 peak disappearance predicted a permanent post-operative deficit in 4 of 4 patients (100%), whereas an isolated irreversible C.C.T. increase was only followed by a transitory deficit. Only 1 of 9 patients with no change in S.E.P.s (during a 15 min. T.O.), had a transient hemiparesis: this "false-negative" case will be discussed. This study confirms that S.E.P.s monitoring provides useful warning during aneurysm surgery

  11. Towards an optimal paradigm for simultaneously recording cortical and brainstem auditory evoked potentials.

    Science.gov (United States)

    Bidelman, Gavin M

    2015-02-15

    Simultaneous recording of brainstem and cortical event-related brain potentials (ERPs) may offer a valuable tool for understanding the early neural transcription of behaviorally relevant sounds and the hierarchy of signal processing operating at multiple levels of the auditory system. To date, dual recordings have been challenged by technological and physiological limitations including different optimal parameters necessary to elicit each class of ERP (e.g., differential adaptation/habitation effects and number of trials to obtain adequate response signal-to-noise ratio). We investigated a new stimulus paradigm for concurrent recording of the auditory brainstem frequency-following response (FFR) and cortical ERPs. The paradigm is "optimal" in that it uses a clustered stimulus presentation and variable interstimulus interval (ISI) to (i) achieve the most ideal acquisition parameters for eliciting subcortical and cortical responses, (ii) obtain an adequate number of trials to detect each class of response, and (iii) minimize neural adaptation/habituation effects. Comparison between clustered and traditional (fixed, slow ISI) stimulus paradigms revealed minimal change in amplitude or latencies of either the brainstem FFR or cortical ERP. The clustered paradigm offered over a 3× increase in recording efficiency compared to conventional (fixed ISI presentation) and thus, a more rapid protocol for obtaining dual brainstem-cortical recordings in individual listeners. We infer that faster recording of subcortical and cortical potentials might allow more complete and sensitive testing of neurophysiological function and aid in the differential assessment of auditory function. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Roles of N-methyl-d-aspartate receptors during the sensory stimulation-evoked field potential responses in mouse cerebellar cortical molecular layer.

    Science.gov (United States)

    Xu, Yin-Hua; Zhang, Guang-Jian; Zhao, Jing-Tong; Chu, Chun-Ping; Li, Yu-Zi; Qiu, De-Lai

    2017-11-01

    The functions of N-methyl-d-aspartate receptors (NMDARs) in cerebellar cortex have been widely studied under in vitro condition, but their roles during the sensory stimulation-evoked responses in the cerebellar cortical molecular layer in living animals are currently unclear. We here investigated the roles of NMDARs during the air-puff stimulation on ipsilateral whisker pad-evoked field potential responses in cerebellar cortical molecular layer in urethane-anesthetized mice by electrophysiological recording and pharmacological methods. Our results showed that cerebellar surface administration of NMDA induced a dose-dependent decrease in amplitude of the facial stimulation-evoked inhibitory responses (P1) in the molecular layer, accompanied with decreases in decay time, half-width and area under curve (AUC) of P1. The IC 50 of NMDA induced inhibition in amplitude of P1 was 46.5μM. In addition, application of NMDA induced significant increases in the decay time, half-width and AUC values of the facial stimulation-evoked excitatory responses (N1) in the molecular layer. Application of an NMDAR blocker, D-APV (250μM) abolished the facial stimulation-evoked P1 in the molecular layer. These results suggested that NMDARs play a critical role during the sensory information processing in cerebellar cortical molecular layer in vivo in mice. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. [The modified method registration of kinesthetic evoked potentials and its application for research of proprioceptive sensitivity disorders at spondylogenic cervical myelopathy].

    Science.gov (United States)

    Gordeev, S A; Voronin, S G

    2016-01-01

    To analyze the efficacy of modified (passive radiocarpal articulation flexion/extension) and «standard» (passive radiocarpal articulation flexion) methods of kinesthetic evoked potentials for proprioceptive sensitivity assessment in healthy subjects and patients with spondylotic cervical myelopathy. The study included 14 healthy subjects (4 women and 10 men, mean age 54.1±10.5 years) and 8 patients (2 women and 6 men, mean age 55.8±10.9 years) with spondylotic cervical myelopathy. Muscle-joint sensation was examined during the clinical study. A modified method of kinesthetic evoked potentials was developed. This method differed from the "standard" one by the organization of a cycle including several passive movements,where each new movement differed from the preceding one by the direction. The modified method of kinesthetic evoked potentials ensures more reliable kinesthetic sensitivity assessment due to movement variability. Asignificant increaseof the latent periods of the early components of the response was found in patients compared to healthy subjects. The modified method of kinesthetic evoked potentials can be used for objective diagnosis of proprioceptive sensitivity disorders in patients with spondylotic cervical myelopathy.

  14. Optimum interpulse interval for transcranial electrical train stimulation to elicit motor evoked potentials of maximal amplitude in both upper and lower extremity target muscles.

    NARCIS (Netherlands)

    van Hal, C.; Hoebink, E.; Polak, H.E.; Racz, I.; de Kleuver, M.; Journee, H.L.

    2013-01-01

    Objective: The aim of this study was to determine the optimum interpulse interval (OIPI) for transcranial electrical train stimulation to elicit muscle motor evoked potentials (TES-MEP) with maximal amplitude in upper and lower extremities during intra-operative spinal cord monitoring. Methods:

  15. Pressure-induced basilar membrane position shifts and the stimulus-evoked potentials in the low-frequency region of the guinea pig cochlea

    NARCIS (Netherlands)

    Fridberger, A; vanMaarseveen, JTPW; Scarfone, E; Ulfendahl, M; Flock, B; Flock, A

    1997-01-01

    We have used the guinea pig isolated temporal bone preparation to investigate changes in the nonlinear properties of the tone-evoked cochlear potentials during reversible step displacements of the basilar membrane towards either the scala tympani or the scala vestibuli. The position shifts were

  16. Non-decussating retinal-fugal fibre syndrome. An inborn achiasmatic malformation associated with visuotopic misrouting, visual evoked potential ipsilateral asymmetry and nystagmus

    NARCIS (Netherlands)

    Apkarian, P.; Bour, L. J.; Barth, P. G.; Wenniger-Prick, L.; Verbeeten, B.

    1995-01-01

    We report a newly identified syndrome in which nasal retinal fibres fail to decussate due to the inborn absence of an optic chiasm. Visual evoked potential (VEP) assessment and neuro-opththalmic evaluation in two unrelated, non-albino children revealed the unusual visual pathway anomaly in the form

  17. DEPRESSION OF THE PHOTIC AFTER DISCHARGE OF FLASH EVOKED POTENTIALS BY PHYSOSTIGMINE, CARBARYL AND PROPOXUR AND THE RELATIONSHIP TO INHIBITION OF BRAIN CHOLINESTERASE

    Science.gov (United States)

    The effects of N-methyl carbamate pesticides on the photic after discharge (PhAD) of flash evoked potentials (FEPs) and the relationship between inhibition of brain cholinesterase (ChE) activity and the PhAD were evaluated. FEPs were recorded in Long Evans rats treated with physo...

  18. Acute stress alters auditory selective attention in humans independent of HPA: a study of evoked potentials.

    Directory of Open Access Journals (Sweden)

    Ludger Elling

    Full Text Available BACKGROUND: Acute stress is a stereotypical, but multimodal response to a present or imminent challenge overcharging an organism. Among the different branches of this multimodal response, the consequences of glucocorticoid secretion have been extensively investigated, mostly in connection with long-term memory (LTM. However, stress responses comprise other endocrine signaling and altered neuronal activity wholly independent of pituitary regulation. To date, knowledge of the impact of such "paracorticoidal" stress responses on higher cognitive functions is scarce. We investigated the impact of an ecological stressor on the ability to direct selective attention using event-related potentials in humans. Based on research in rodents, we assumed that a stress-induced imbalance of catecholaminergic transmission would impair this ability. METHODOLOGY/PRINCIPAL FINDINGS: The stressor consisted of a single cold pressor test. Auditory negative difference (Nd and mismatch negativity (MMN were recorded in a tonal dichotic listening task. A time series of such tasks confirmed an increased distractibility occurring 4-7 minutes after onset of the stressor as reflected by an attenuated Nd. Salivary cortisol began to rise 8-11 minutes after onset when no further modulations in the event-related potentials (ERP occurred, thus precluding a causal relationship. This effect may be attributed to a stress-induced activation of mesofrontal dopaminergic projections. It may also be attributed to an activation of noradrenergic projections. Known characteristics of the modulation of ERP by different stress-related ligands were used for further disambiguation of causality. The conjuncture of an attenuated Nd and an increased MMN might be interpreted as indicating a dopaminergic influence. The selective effect on the late portion of the Nd provides another tentative clue for this. CONCLUSIONS/SIGNIFICANCE: Prior studies have deliberately tracked the adrenocortical influence

  19. Quadratic adaptive algorithm for solving cardiac action potential models.

    Science.gov (United States)

    Chen, Min-Hung; Chen, Po-Yuan; Luo, Ching-Hsing

    2016-10-01

    An adaptive integration method is proposed for computing cardiac action potential models accurately and efficiently. Time steps are adaptively chosen by solving a quadratic formula involving the first and second derivatives of the membrane action potential. To improve the numerical accuracy, we devise an extremum-locator (el) function to predict the local extremum when approaching the peak amplitude of the action potential. In addition, the time step restriction (tsr) technique is designed to limit the increase in time steps, and thus prevent the membrane potential from changing abruptly. The performance of the proposed method is tested using the Luo-Rudy phase 1 (LR1), dynamic (LR2), and human O'Hara-Rudy dynamic (ORd) ventricular action potential models, and the Courtemanche atrial model incorporating a Markov sodium channel model. Numerical experiments demonstrate that the action potential generated using the proposed method is more accurate than that using the traditional Hybrid method, especially near the peak region. The traditional Hybrid method may choose large time steps near to the peak region, and sometimes causes the action potential to become distorted. In contrast, the proposed new method chooses very fine time steps in the peak region, but large time steps in the smooth region, and the profiles are smoother and closer to the reference solution. In the test on the stiff Markov ionic channel model, the Hybrid blows up if the allowable time step is set to be greater than 0.1ms. In contrast, our method can adjust the time step size automatically, and is stable. Overall, the proposed method is more accurate than and as efficient as the traditional Hybrid method, especially for the human ORd model. The proposed method shows improvement for action potentials with a non-smooth morphology, and it needs further investigation to determine whether the method is helpful during propagation of the action potential. Copyright © 2016 Elsevier Ltd. All rights

  20. Investigation of potential artefactual changes in measurements of impedance changes during evoked activity: implications to electrical impedance tomography of brain function.

    Science.gov (United States)

    Aristovich, Kirill Y; Dos Santos, Gustavo S; Holder, David S

    2015-06-01

    Electrical impedance tomography (EIT) could provide images of fast neural activity in the adult human brain with a resolution of 1 ms and 1 mm by imaging impedance changes which occur as ion channels open during neuronal depolarization. The largest changes occur at dc and decrease rapidly over 100 Hz. Evoked potentials occur in this bandwidth and may cause artefactual apparent impedance changes if altered by the impedance measuring current. These were characterized during the compound action potential in the walking leg nerves of Cancer pagurus, placed on Ag/AgCl hook electrodes, to identify how to avoid artefactual changes during brain EIT. Artefact-free impedance changes (δZ) decreased with frequency from -0.045 ± 0.01% at 225 Hz to -0.02 ± 0.01% at 1025 Hz (mean ± 1 SD, n = 24 in 12 nerves) which matched changes predicted by a finite element model. Artefactual δZ reached c.300% and 50% of the genuine membrane impedance change at 225 Hz and 600 Hz respectively but decreased with frequency of the applied current and was negligible above 1 kHz. The proportional amplitude (δZ (%)) of the artefact did not vary significantly with the amplitude of injected current of 5-20 µA pp. but decreased significantly from -0.09 ± 0.024 to -0.03 ± 0.023% with phase of 0 to 45°. For fast neural EIT of evoked activity in the brain, artefacts may arise with applied current of >10 µA. Independence of δZ with respect to phase but not the amplitude of applied current controls for them; they can be minimized by randomizing the phase of the applied measuring current and excluded by recording at >1 kHz.

  1. Fiber Optic Detection of Action Potentials in Axons

    National Research Council Canada - National Science Library

    Smela, Elisabeth

    2006-01-01

    In prior exploratory research, we had designed a fiber optic sensor utilizing a long period Bragg grating for the purpose of detecting action potentials in axons optically, through a change in index...

  2. Auditory evoked potentials to speech and nonspeech stimuli are associated with verbal skills in preschoolers.

    Science.gov (United States)

    Kuuluvainen, Soila; Leminen, Alina; Kujala, Teija

    2016-06-01

    Children's obligatory auditory event-related potentials (ERPs) to speech and nonspeech sounds have been shown to associate with reading performance in children at risk or with dyslexia and their controls. However, very little is known of the cognitive processes these responses reflect. To investigate this question, we recorded ERPs to semisynthetic syllables and their acoustically matched nonspeech counterparts in 63 typically developed preschoolers, and assessed their verbal skills with an extensive set of neurocognitive tests. P1 and N2 amplitudes were larger for nonspeech than speech stimuli, whereas the opposite was true for N4. Furthermore, left-lateralized P1s were associated with better phonological and prereading skills, and larger P1s to nonspeech than speech stimuli with poorer verbal reasoning performance. Moreover, left-lateralized N2s, and equal-sized N4s to both speech and nonspeech stimuli were associated with slower naming. In contrast, children with equal-sized N2 amplitudes at left and right scalp locations, and larger N4s for speech than nonspeech stimuli, performed fastest. We discuss the possibility that children’s ERPs reflect not only neural encoding of sounds, but also sound quality processing, memory-trace construction, and lexical access. The results also corroborate previous findings that speech and nonspeech sounds are processed by at least partially distinct neural substrates. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  3. Auditory evoked potentials in patients with major depressive disorder measured by Emotiv system.

    Science.gov (United States)

    Wang, Dongcui; Mo, Fongming; Zhang, Yangde; Yang, Chao; Liu, Jun; Chen, Zhencheng; Zhao, Jinfeng

    2015-01-01

    In a previous study (unpublished), Emotiv headset was validated for capturing event-related potentials (ERPs) from normal subjects. In the present follow-up study, the signal quality of Emotiv headset was tested by the accuracy rate of discriminating Major Depressive Disorder (MDD) patients from the normal subjects. ERPs of 22 MDD patients and 15 normal subjects were induced by an auditory oddball task and the amplitude of N1, N2 and P3 of ERP components were specifically analyzed. The features of ERPs were statistically investigated. It is found that Emotiv headset is capable of discriminating the abnormal N1, N2 and P3 components in MDD patients. Relief-F algorithm was applied to all features for feature selection. The selected features were then input to a linear discriminant analysis (LDA) classifier with leave-one-out cross-validation to characterize the ERP features of MDD. 127 possible combinations out of the selected 7 ERP features were classified using LDA. The best classification accuracy was achieved to be 89.66%. These results suggest that MDD patients are identifiable from normal subjects by ERPs measured by Emotiv headset.

  4. Characterization of the cerebral activity by time–frequency representation of evoked EEG potentials

    International Nuclear Information System (INIS)

    Clariá, Francesc; Vallverdú, Montserrat; Romero, Sergio; Caminal, Pere; Riba, Jordi; Barbanoj, Manuel J

    2011-01-01

    Event-related brain potentials (ERPs) are the electrical response of the brain while performing a particular task. Methods traditionally used to study ERPs measure the amplitude and duration of the waveform in order to quantify the changes, being signal morphology dependent. However, the frequency characteristics of those events remain uncovered. The aim of this work was the study of new measures to characterize, by means of time–frequency representation (TFR) techniques, the ERPs recorded while subjects conducted a choice reaction time task (Ericksen flanker task) following the administration of different alprazolam doses. Several measures defined from energy, instantaneous frequency and group delay functions were obtained by means of TFR techniques applied to the Choi–Williams distribution (CWD) of EEG signals. These measures, which are signal morphology independent, were studied in four frequency bands, δ (0–4 Hz), θ (4–8 Hz), α (8–15 Hz), β (15–30 Hz), and for certain time periods. Based on these measures, differences between ERPs were analyzed by comparing the different response types (successes or successfully corrected failures) of the subject performing the task, and comparing the applied drug doses. For each subject, the CWD of EEG signals was applied in two different ways: (a) all ERPs were averaged per channel, and then the CWD was applied; (b) the CWD was applied to each one of the ERPs. When the CWD was applied to each ERP, the energy measures in the δ, θ and β bands, the instantaneous frequency measures in the α and β bands, and the group delay measures in the δ, θ and α bands showed a statistically significant level p < 0.0005 in the analysis of the response type. Also, the energy measures in the θ and β bands and the instantaneous frequency measures in the α band showed statistically significant differences (p < 0.0005) between placebo and low and high drug doses. In contrast, poor results were obtained when all epochs of

  5. Correlation of Superior Canal Dehiscence Surface Area With Vestibular Evoked Myogenic Potentials, Audiometric Thresholds, and Dizziness Handicap.

    Science.gov (United States)

    Hunter, Jacob B; O'Connell, Brendan P; Wang, Jianing; Chakravorti, Srijata; Makowiec, Katie; Carlson, Matthew L; Dawant, Benoit; McCaslin, Devin L; Noble, Jack H; Wanna, George B

    2016-09-01

    To correlate objective measures of vestibular and audiometric function as well as subjective measures of dizziness handicap with the surface area of the superior canal dehiscence (SCD). Retrospective chart review and radiological analysis. Single tertiary academic referral center. Preoperative computed tomography imaging, patient survey, audiometric thresholds, and vestibular evoked myogenic potential (VEMP) testing in patients with confirmed SCD. Image analysis techniques were developed to measure the surface area of each SCD in computed tomography imaging. Preoperative ocular and cervical VEMPs, air and bone conduction thresholds, air-bone gap, dizziness handicap inventory scores, and surface area of the SCD. Fifty-three patients (mean age 52.7 yr) with 84 SCD were analyzed. The median surface area of dehiscence was 1.44 mm (0.068-8.23 mm). Ocular VEMP amplitudes (r = 0.61, p handicap and surface area was identified. Among patients with confirmed SCD, ocular and cervical VEMP amplitudes, cervical VEMP thresholds, and air conduction thresholds at 250 Hz are significantly correlated with the surface area of the dehiscence.

  6. [A wireless smart home system based on brain-computer interface of steady state visual evoked potential].

    Science.gov (United States)

    Zhao, Li; Xing, Xiao; Guo, Xuhong; Liu, Zehua; He, Yang

    2014-10-01

    Brain-computer interface (BCI) system is a system that achieves communication and control among humans and computers and other electronic equipment with the electroencephalogram (EEG) signals. This paper describes the working theory of the wireless smart home system based on the BCI technology. We started to get the steady-state visual evoked potential (SSVEP) using the single chip microcomputer and the visual stimulation which composed by LED lamp to stimulate human eyes. Then, through building the power spectral transformation on the LabVIEW platform, we processed timely those EEG signals under different frequency stimulation so as to transfer them to different instructions. Those instructions could be received by the wireless transceiver equipment to control the household appliances and to achieve the intelligent control towards the specified devices. The experimental results showed that the correct rate for the 10 subjects reached 100%, and the control time of average single device was 4 seconds, thus this design could totally achieve the original purpose of smart home system.

  7. Cervical and ocular vestibular-evoked myogenic potentials in vestibular neuritis: comparison between air- and bone-conducted stimulation.

    Science.gov (United States)

    Oh, Sun-Young; Kim, Ji-Soo; Yang, Tae-Ho; Shin, Byoung-Soo; Jeong, Seul-Ki

    2013-08-01

    To clarify the changes of cervical (cVEMP) and ocular (oVEMP) vestibular evoked myogenic potentials induced by air-conducted sound (ACS) and bone-conducted vibration (BCV) in patients with vestibular neuritis (VN), patients with VN (n = 30) and normal controls (n = 45) underwent recording of cVEMP and oVEMP in response to ACS (1,000 Hz, 5 ms, tone bursts) and BCV (500 Hz, short tone burst). Patients with VN showed a high proportion of oVEMP abnormalities in response to both ACS (80.0 %) and BCV at the forehead (Fz, 73.3 %) or the mastoid (76.7 %). In contrast, cVEMPs were mostly normal with both ACS and BCV in the patients. The dissociations in the abnormalities of cVEMP and oVEMP induced by ACS and BCV at the mastoids and at the forehead in patients with VN suggest that oVEMP reflects functions of the superior vestibular nerve and most likely the utricular function. The results of our study suggest that oVEMP induced by either ACS or BCV appears to depend on integrity of the superior vestibular nerve, possibly due to the utricular afferents travelling in it. In contrast, cVEMP elicited by either ACS or BCV may reflect function of the saccular afferents running in the inferior vestibular nerve.

  8. Are There Abnormalities in Peripheral and Central Components of Somatosensory Evoked Potentials in Non-Specific Chronic Low Back Pain?

    Science.gov (United States)

    Puta, Christian; Franz, Marcel; Blume, Kathrin R; Gabriel, Holger H W; Miltner, Wolfgang H R; Weiss, Thomas

    2016-01-01

    Chronic low back pain (CLBP) was shown to be associated with longer reflex response latencies of trunk muscles during external upper limb perturbations. One theoretical, but rarely investigated possibility for longer reflex latencies might be related to modulated somatosensory information processing. Therefore, the present study investigated somatosensory evoked potentials (SEPs) to median nerve stimulation in CLBP patients and healthy controls (HC). Latencies of the peripheral N9 SEP component were used as the primary outcome. In addition, latencies and amplitudes of the central N20 SEP component, sensory thresholds, motor thresholds and nerve conduction velocity were also analyzed in CLBP patients and HC. There is a trend for the CLBP patients to exhibit longer N9 latencies at the ipsilateral Erb's point compared to HC. This trend is substantiated by significantly longer N9 latencies in CLBP patients compared to normative data. None of the other parameters showed any significant difference between CLBP patients and HC. Overall, our data indicate small differences of the peripheral N9 SEP component; however, these differences cannot explain the reflex delay observed in CLBP patients. While it was important to rule out the contribution of early somatosensory processing and to elucidate its contribution to the delayed reflex responses in CLBP patients, further research is needed to find the primary source(s) of time-delayed reflexes in CLBP.

  9. Are there abnormalities in peripheral and central components of somatosensory evoked potentials in non - specific chronic low back pain ?

    Directory of Open Access Journals (Sweden)

    Christian Puta

    2016-10-01

    Full Text Available Chronic low back pain (CLBP was shown to be associated with longer reflex response latencies of trunk muscles during external upper limb perturbations. One theoretical, but rarely investigated possibility for longer reflex latencies might be related to modulated somatosensory information processing. Therefore, the present study investigated somatosensory evoked potentials (SEPs to median nerve stimulation in CLBP patients and healthy controls (HC. Latencies of the peripheral N9 SEP component were used as primary outcome. In addition, latencies and amplitudes of the central N20 SEP component, sensory thresholds, motor thresholds, and nerve conduction velocity were also analyzed in CLBP patients and HC. There is a trend for the CLBP patients to exhibited longer N9 latencies at the ipsilateral Erb’s point compared to HC. This trend is substantiated by significantly longer N9 latencies in CLBP patients compared to normative data. None of the other parameters showed any significant difference between CLBP patients and HC. Overall, our data indicate small differences of the peripheral N9 SEP component; however, these differences cannot explain the reflex delay observed in CLBP patients. While it was important to rule out the contribution of early somatosensory processing and to elucidate its contribution to the delayed reflex responses in CLBP patients, further research is needed to find the primary source(s of time-delayed reflexes in CLBP.

  10. Sex-specific automatic responses to infant cries: TMS reveals greater excitability in females than males in motor evoked potentials

    Directory of Open Access Journals (Sweden)

    Irene eMessina

    2016-01-01

    Full Text Available Neuroimaging reveals that infant cries activate parts of the premotor cortical system. To validate this effect in a more direct way, we used event-related transcranial magnetic stimulation (TMS. Here, we investigated the presence and the time course of modulation of motor cortex excitability in young adults who listened to infant cries. Specifically, we recorded motor evoked potentials (MEPs from the biceps brachii (BB and interosseus dorsalis primus (ID1 muscles as produced by TMS delivered from 0 to 250 ms from sound onset in six steps of 50 ms in 10 females and 10 males. We observed an excitatory modulation of MEPs at 100 ms from the onset of the infant cry specific to females and to the ID1 muscle. We regard this modulation as a response to natural cry sounds because it was delayed, attenuated to stimuli increasingly different from natural cry, and was absent in a separate group of females who listened to non-cry stimuli physically matched to natural infant cries. Furthermore, the 100-ms latency of this modulation is not compatible with a voluntary reaction to the stimulus but suggests an automatic, bottom-up audiomotor association. The brains of adult females appear to be tuned to respond to infant cries with automatic motor excitation. This effect may reflect the greater and longstanding burden on females in caregiving infants.

  11. Trigeminal somatosensorial evoked potentials suggest increased excitability during interictal period in patients with long disease duration in migraine.

    Science.gov (United States)

    Abanoz, Yesim; Abanoz, Yasin; Gündüz, Aysegül; Savrun, Feray Karaali

    2016-01-26

    Migraine pathogenesis is suggested to involve many structures in cerebral cortex, brainstem and trigeminovascular system. Electrophysiological studies revealed loss of habituation, decreased cortical preactivation, segmental hypersensitivity and reduction in control of inhibitory descending pathways. Given these information, we aimed to evaluate the excitability changes of the trigeminal pathway in the cortex and brainstem in migraine using trigeminal nerve somatosensory evoked potentials (TSEP). Fifty-one women with migraine without aura and 32 age-matched healthy women were included. TSEPs were recorded in migraine patients during interictal period and in healthy subjects. Sensory thresholds, stimulation intensities, latencies of N1, P1, N2 and P2 waves as well as N1/P1 and N2/P1 amplitudes were measured. Comparisons of ipsilateral latencies with N1-P1 and N2-P1 amplitudes between migraine and control groups showed no difference. Sensory thresholds were also similar. Stimulation thresholds decreased as the attack frequency increased and ipsilateral N1/P1 amplitude increased with prolonged disease duration (p=0.043). Our study did not show significant difference between migraine patients and healthy subjects during interictal period. However, migraine with long duration affects the excitability of the cortical and brainstem trigeminal pathways even during interictal periods. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  12. Age-related decrease in sensitivity to electrical stimulation is unrelated to skin conductance: an evoked potentials study.

    Science.gov (United States)

    Kemp, J; Després, O; Pebayle, T; Dufour, A

    2014-03-01

    With aging, skin is likely to become less hydrated, thereby increasing its resistance to electrical current. This, rather than sensorial/perceptual differences per se, may be the primary cause of differences between younger and older adults in somatosensorial perception in response to electrical stimuli. To assess whether aging alters the perception of electrical stimulation, we compared the perceived intensity of electrical stimuli in younger and older subjects, considering both setpoint intensities and the actual intensities of the current passing through subjects' skin. This resulted in reliable information about electrical somatosensory perception in both groups at equivalent received amounts of current. Somatosensory evoked potentials (SEPs) enabled the objective evaluation of somatosensitivity in both groups. At equivalent received intensities, the mean ratings were significantly lower in older than in younger subjects. SEPs confirmed these results, with older adults having longer latencies and reduced amplitudes. Our results suggest that age-related decreases in somatosensitivity to electrical stimuli are not due to cutaneous physiological changes. Age-related increases in electrical somatosensorial and pain thresholds seem to be more attributable to dysfunctions of the peripheral and/or central nervous system, than to non-optimal activation of somatosensorial receptors/nerve fibers due to cutaneous physiological changes. Copyright © 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  13. Comparison of the effects of aminoguanidine and L-carnitine treatments on somatosensorial evoked potentials in alloxan-diabetic rats.

    Science.gov (United States)

    Yildiz, O; Ozata, M; Ozkardeş, A; Deniz, G; Yildirimkaya, M; Corakçi, A; Yardim, M; Gündoğan, M A

    1996-10-01

    The effects of aminoguanidine (AG) and L-carnitine (LC) on somatosensorial evoked potential (SEP) latency and neural levels of thiobarbituric acid reactive substances (TBARS), products of lipid peroxidation, were compared in alloxan-diabetic rats. AG and LC were given to diabetic rats starting from the 3rd week after the induction of diabetes and lasting for 4 weeks. SEP latency was measured by stimulating via caudal nerve and recording via cortex, once weekly during the treatments. Diabetes caused deficits in SEP (P < 0.05 vs non-diabetic control rats, respectively). AG and LC restored SEP latencies slightly but not significantly, with the exception of the prominent effect of AG at the first week and both treatments at the 4th week of the treatments (P < 0.05 vs untreated diabetic rats, respectively). Diabetes caused elevation in neural TBARS levels (P < 0.05 vs non-diabetic group), which was prevented by both AG and LC (P < 0.05 vs untreated diabetic rats, respectively). Weight and the glucose levels were not influenced by the treatments. Our results suggest that AG improves SEP latencies better than LC. Our results also suggest that the beneficial effects of both AG and LC on diabetic neuropathy are not associated with the regulation of glycemia, but these effects may be related in part with prevention of lipid peroxidation.

  14. Short somatosensory evoked potentials in patients with Fukuyama type congenital muscular dystrophy. A comparison with CT and MRI findings

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    Namba, Yukiko; Maegaki, Yoshihiro; Maeoka, Yukinori; Yoshimura, Masaki; Takeshita, Kenzo [Tottori Univ., Yonago (Japan). School of Medicine; Houdou, Sadataka; Ishii, Shougo; Ohtani, Kyoichi

    1995-09-01

    Seven patients with Fukuyama type congenital muscular dystrophy were studied. Low density areas (LDs) in the cerebral white matter on cranial CT were present in all 4 patients younger than 13 years of age and in 1 of 3 adult patients. LDs corresponded to low signals on T{sub 1} weighted MRI image and high signals on T{sub 2} weighted MRI image. The follow-up MRI showed a decreased tendency of the abnormal signals in 2 patients. Short somatosensory evoked potentials (SSEPs) in two infants, aged 4 months and 8 months, showed absent or depressed N1 amplitudes and delayed interpeak latencies from P3 to N1. N1 amplitudes increased on follow-up studies. SSEPs of five patients, who were older than 2 years of age, showed normal N1-P3 latencies. Amplitude of N1 was low in 2 patients with LD. Since the absent or depressed amplitude and delayed latency of N1 improved with the decrease of abnormal signals on MRI, we considered that N1 abnormalities show delayed myelination. (author).

  15. Non-invasive single-trial detection of variable population spike responses in human somatosensory evoked potentials.

    Science.gov (United States)

    Waterstraat, Gunnar; Scheuermann, Manuel; Curio, Gabriel

    2016-03-01

    Somatosensory evoked potentials (SEPs) around 600 Hz ('σ-bursts') are correlates of cortical population spikes. Recently, single-trial σ-bursts were detected in human scalp EEG using 29-channel low-noise recordings in an electromagnetically shielded room. To achieve clinical applicability, this study aimed to establish a protocol using only 8 EEG channels in an unshielded environment and to quantify the variability of σ-bursts. Median nerve SEPs were recorded in 10 healthy subjects using a custom-built low-noise EEG amplifier. A detection algorithm for single-trial σ-bursts was trained as combination of spatio-temporal filters and a non-linear classifier. The single-trial responses were probed for the presence of significant increases of amplitude and variability. Single-trial σ-burst detection succeeded with Detection Rates and Positive Predictive Values above 80% in subjects with high SNR. A significant inter-trial variability in the amplitudes of early low-frequency SEPs and σ-bursts could be demonstrated. Single-trial σ-bursts can be detected on scalp-EEG using only 8 EEG channels in an electromagnetically disturbed environment. The combination of dedicated hardware and detection algorithms allows quantifying and describing their variability. The variability of population spikes in the human somatosensory cortex can be traced non-invasively in a clinical setting. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  16. Long latency auditory evoked potentials and central auditory processing in children with reading and writing alterations: Preliminary data

    Directory of Open Access Journals (Sweden)

    Soares, Aparecido José Couto

    2011-10-01

    Full Text Available Introduction: Presently, it is admitted that individuals with reading and writing alterations may present delay in the development of listening skills, which may interfere in the learning process. The assessment of the listening skills can occur in a behavioral way, through central auditory processing (CAP tests, or by electrophysiological assessment highlighting the long latency auditory evoked potentials (LLAEP. The use of the LLAEP as a means of complementary assessment of individuals with reading and writing alterations can become an important data both for further characterization of the alterations, as for the therapeutic guidance of this population. Objective: Characterize the CAP and the LLAEP in children with reading and writing alterations. Method: Research approved by the Institution's Ethic Commission under nº 305/10. The assessment of CAP and LLAEP was performed in 12 children aged between 8 and 12 years old (average of 10,6 years, with reading and writing alterations confirmed in specific evaluation. Results: The most altered CAP skills were temporal ordination and figure-ground for linguistic sounds. There were found altered results in P300 and in MMN. Conclusion: The individuals with reading and writing alterations performed below the expected on CAP tests. The MMN allowed a better characterization of the auditory function of this population. There was evidence of association between the CAP results and the alteration of the LLAEP.

  17. Effect of respiration on heartbeat-evoked potentials during sleep in children with sleep-disordered breathing.

    Science.gov (United States)

    Baumert, Mathias; Pamula, Yvonne; Kohler, Mark; Martin, James; Kennedy, Declan; Nalivaiko, Eugene; Immanuel, Sarah A

    2015-05-01

    Heartbeat-evoked potentials (HEPs) in electroencephalogram (EEG) provide a quantitative measure of cardiac interoception during sleep. We previously reported reduced HEPs in children with sleep-disordered breathing (SDB), indicative of attenuated cardiac information processing. The objective of this study was to investigate the link between HEP and respiration. From the overnight polysomnograms of 40 healthy children and 40 children with SDB, we measured HEPs during epochs of stage 2, slow-wave and rapid eye movement (REM) sleep free of abnormal respiratory events. HEPs were analysed with respect to respiratory phase. We observed a marked association between respiratory phase and HEP in children with SDB during REM sleep, but not in normal children. In children with SDB, HEP waveforms were attenuated during expiration compared to inspiration. Following adenotonsillectomy, expiratory HEP peak amplitude increased in the SDB children and was no longer different from those of normal children. The expiratory phase of respiration is primarily associated with attenuated cardiac information processing in children with SDB, establishing a pathophysiological link between breathing and HEP attenuation. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Laser-Evoked Potentials in Fibromyalgia: The Influence of Greater Occipital Nerve Stimulation on Cerebral Pain Processing.

    Science.gov (United States)

    Plazier, Mark; Ost, Jan; Snijders, Erwin; Gilbers, Martijn; Vancamp, Tim; De Ridder, Dirk; Vanneste, Sven

    2015-07-01

    Fibromyalgia causes widespread musculo-skeletal pain in the four quadrants of the body. Greater occipital nerve stimulation has recently shown beneficial effects in fibromyalgia patients on pain, fatigue, and mood disorders. Laser-evoked potentials (LEPs) are used for research to understand the pathophysiological mechanisms of pain and to evaluate the effects of pain treatment. In fibromyalgia patients, LEPs tend to have a higher N2 amplitude, a tendency to shorter latencies, and patients have a lower pain threshold. Greater occipital nerve stimulation might exert a modulation of the medial pain pathways processing the affective motivational components of pain (unpleasantness) as well as the descending pain inhibitory pathways (reducing pain), both of which are contributing to the N2P2 peak. To test this hypothesis, the authors performed LEPs in a group of fibromyalgia patients with and without greater occipital nerve stimulation. Occipital nerve stimulation does not alter the amplitudes of the LEP recordings, although a significant difference in latencies can be seen. More specifically, latencies of the N2P2 increased in the condition after stimulation, and especially at the Pz electrode. Our results suggest Occipital Nerve Stimulation (ONS) induces a modification of the balance between antinociceptive pain inhibitory pathways and pain-provoking pathways. © 2015 International Neuromodulation Society.

  19. Effect of personal music system use on sacculocollic reflex assessed by cervical vestibular-evoked myogenic potential: A preliminary investigation

    Directory of Open Access Journals (Sweden)

    Niraj Kumar Singh

    2016-01-01

    Full Text Available Listening to music through a portable personal music system (PMS is a growing trend, especially among the youth. The preferred listening level in such kinds of PMS has been reported to cross the safe levels and its impact on the auditory system was demonstrated in several previous investigations. Owing to the commonality in several aspects between the auditory and the vestibular systems, it appears likely that the deleterious effects of PMS use could also be impinging on the vestibular system, which has never been investigated. The present study therefore, aimed at evaluating the effects of PMS use on the sacculocollic reflex assessed by the cervical vestibular-evoked myogenic potential (cVEMP technique. Thirty-two regular PMS users and 32 nonregular PMS users underwent cVEMP testing using alternating polarity 500 Hz tone bursts. The results revealed no significant group difference in latencies and interaural asymmetry ratio. However, the cVEMP was significantly reduced in the group of individuals in whom the diffused field equivalent sound pressure levels (SPLs were above the damage risk criteria (DRC compared to those with diffused field equivalent SPLs below it (P< 0.01. Therefore, the use of PMS at high levels of volume controls could be deleterious to the vestibular well-being of an individual.

  20. Effect of treatment with sitagliptin on somatosensory-evoked potentials and metabolic control in patients with type 2 diabetes mellitus.

    Science.gov (United States)

    Barros, Joelma Ines Tagliapietra; Fechine, Francisco Vagnaldo; Montenegro Júnior, Renan Magalhães; Vale, Otoni Cardoso do; Fernandes, Virgínia Oliveira; Souza, Marcellus Henrique Loiola Ponte de; Cunha, Gilmara Holanda da; Moraes, Manoel Odorico de; d'Alva, Catarina Brasil; Moraes, Maria Elisabete Amaral de

    2014-06-01

    To evaluate the effect of sitagliptin on somatosensory-evoked potentials (SEPs) and metabolic control in patients with type 2 diabetes mellitus without clinical diabetic neuropathy. Interventional, prospective, and open study. Patients with less than six months from the diagnosis were included. Examinations of SEPs and laboratory tests at fasting and after food stimulation were performed before and after three months of treatment with sitagliptin (100 mg/day). There was a reduction in the mean levels of HbA1c (P fasting glucose (P = 0.001), total cholesterol (P = 0.019), and ALT (P = 0.022). An increase in active GLP-1 was found at the end of the study (P = 0.0025). Several SEPs showed statistically significant differences when analyzed before and after treatment with sitagliptin. The results give a glimpse of the possible use of sitagliptin in the treatment of some neurodegenerative conditions of the peripheral nervous system, in addition to its already established role in glycemic control.

  1. The steady-state visual evoked potential reveals neural correlates of the items encoded into visual working memory.

    Science.gov (United States)

    Peterson, Dwight J; Gurariy, Gennadiy; Dimotsantos, Gabriella G; Arciniega, Hector; Berryhill, Marian E; Caplovitz, Gideon P

    2014-10-01

    Visual working memory (VWM) capacity limitations are estimated to be ~4 items. Yet, it remains unclear why certain items from a given memory array may be successfully retrieved from VWM and others are lost. Existing measures of the neural correlates of VWM cannot address this question because they measure the aggregate processing of the entire stimulus array rather than neural signatures of individual items. Moreover, this cumulative processing is usually measured during the delay period, thereby reflecting the allocation of neural resources during VWM maintenance. Here, we use the steady-state visual evoked potential (SSVEP) to identify the neural correlates of individual stimuli at VWM encoding and test two distinct hypotheses: the focused-resource hypothesis and the diffuse-resource hypothesis, for how the allocation of neural resources during VWM encoding may contribute to VWM capacity limitations. First, we found that SSVEP amplitudes were larger for stimuli that were later remembered than for items that were subsequently forgotten. Second, this pattern generalized so that the SSVEP amplitudes were also larger for the unprobed stimuli in correct compared to incorrect trials. These data are consistent with the diffuse-resource view in which attentional resources are broadly allocated across the whole stimulus array. These results illustrate the important role encoding mechanisms play in limiting the capacity of VWM. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Sequence detection analysis based on canonical correlation for steady-state visual evoked potential brain computer interfaces.

    Science.gov (United States)

    Cao, Lei; Ju, Zhengyu; Li, Jie; Jian, Rongjun; Jiang, Changjun

    2015-09-30

    Steady-state visual evoked potential (SSVEP) has been widely applied to develop brain computer interface (BCI) systems. The essence of SSVEP recognition is to recognize the frequency component of target stimulus focused by a subject significantly present in EEG spectrum. In this paper, a novel statistical approach based on sequence detection (SD) is proposed for improving the performance of SSVEP recognition. This method uses canonical correlation analysis (CCA) coefficients to observe SSVEP signal sequence. And then, a threshold strategy is utilized for SSVEP recognition. The result showed the classification performance with the longer duration of time window achieved the higher accuracy for most subjects. And the average time costing per trial was lower than the predefined recognition time. It was implicated that our approach could improve the speed of BCI system in c