Sample records for human evoked potential

  1. Evoked Potentials and Human Intelligence. (United States)

    Ertl, John P.; Schafer, Edward W. P.

    Evidence of a relationship between the electrical responses of the human brain and psychometric measure of intelligence is presented. These involuntary cortical responses, known as average evoked potentials are considered to be the electrical signs of information processing by the brain. The time delays of these responses from presentation of a…

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

    DEFF Research Database (Denmark)

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


    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 s......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...

  3. Adaptive Fourier series modeling of time-varying evoked potentials: study of human somatosensory evoked response to etomidate anesthetic. (United States)

    Thakor, N V; Vaz, C A; McPherson, R W; Hanley, D F


    Evoked potentials (EPs) have traditionally been analyzed in time domain, with amplitude and latency of various signal components used in clinical interpretation. A new approach, called adaptive Fourier series modeling (FSM), is presented here. Dynamic changes in magnitudes of Fourier coefficients are analyzed for diagnostic purposes. In order to estimate the time-varying changes in the Fourier coefficients of noisy signals, a least mean-square filtering algorithm is applied. Results of computer simulations as well as experimental data are presented. Time-varying trends are presented in a new compressed evoked spectrum format. These techniques are applied to the study of alterations in human somatosensory EPs caused by the intravenous administration of etomidate during neurosurgical procedures. Amplitude increases of the order of 200-500% occurring within a time span of about 100 sec were captured. Due to its superior convergence properties, the adaptive FSM technique estimates more rapid changes in amplitude and latency than exponentially weighted averaging or moving window averaging schemes.

  4. Enhancement of the amplitude of somatosensory evoked potentials following magnetic pulse stimulation of the human brain. (United States)

    Seyal, M; Browne, J K; Masuoka, L K; Gabor, A J


    In this study we have demonstrated an enhancement of cortically generated wave forms of the somatosensory evoked potential (SEP) following magnetic pulse stimulation of the human brain. Subcortically generated activity was unaltered. The enhancement of SEP amplitude was greatest when the median nerve was stimulated 30-70 msec following magnetic pulse stimulation over the contralateral parietal scalp. We posit that the enhancement of the SEP is the result of synchronization of pyramidal cells in the sensorimotor cortex resulting from the magnetic pulse.

  5. The N2-P3 complex of the evoked potential and human performance (United States)

    Odonnell, Brian F.; Cohen, Ronald A.


    The N2-P3 complex and other endogenous components of human evoked potential provide a set of tools for the investigation of human perceptual and cognitive processes. These multidimensional measures of central nervous system bioelectrical activity respond to a variety of environmental and internal factors which have been experimentally characterized. Their application to the analysis of human performance in naturalistic task environments is just beginning. Converging evidence suggests that the N2-P3 complex reflects processes of stimulus evaluation, perceptual resource allocation, and decision making that proceed in parallel, rather than in series, with response generation. Utilization of these EP components may provide insights into the central nervous system mechanisms modulating task performance unavailable from behavioral measures alone. The sensitivity of the N2-P3 complex to neuropathology, psychopathology, and pharmacological manipulation suggests that these components might provide sensitive markers for the effects of environmental stressors on the human central nervous system.

  6. International Evoked Potentials Symposium

    CERN Document Server


    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...

  7. Evoked potentials in multiple sclerosis. (United States)

    Kraft, George H


    Before the development of magnetic resonance imaging (MRI), evoked potentials (EPs)-visual evoked potentials, somatosensory evoked potentials, and brain stem auditory evoked responses-were commonly used to determine a second site of disease in patients being evaluated for possible multiple sclerosis (MS). The identification of an area of the central nervous system showing abnormal conduction was used to supplement the abnormal signs identified on the physical examination-thus identifying the "multiple" in MS. This article is a brief overview of additional ways in which central nervous system (CNS) physiology-as measured by EPs-can still contribute value in the management of MS in the era of MRIs.

  8. Anxiety affects the amplitudes of red and green color-elicited flash visual evoked potentials in humans. (United States)

    Hosono, Yuki; Kitaoka, Kazuyoshi; Urushihara, Ryo; Séi, Hiroyoshi; Kinouchi, Yohsuke


    It has been reported that negative emotional changes and conditions affect the visual faculties of humans at the neural level. On the other hand, the effects of emotion on color perception in particular, which are based on evoked potentials, are unknown. In the present study, we investigated whether different anxiety levels affect the color information processing for each of 3 wavelengths by using flash visual evoked potentials (FVEPs) and State-Trait Anxiety Inventory. In results, significant positive correlations were observed between FVEP amplitudes and state or trait anxiety scores in the long (sensed as red) and middle (sensed as green) wavelengths. On the other hand, short-wavelength-evoked FVEPs were not correlated with anxiety level. Our results suggest that negative emotional conditions may affect color sense processing in humans.

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

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    Petit Laurent


    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.

  10. Prandial states modify the reactivity of the gustatory cortex using gustatory evoked potentials in humans

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    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 as NCT

  11. [Evoked potentials and inhalation anesthetics]. (United States)

    Thiel, A; Russ, W; Hempelmann, G


    Intraoperative monitoring of evoked potentials can be affected by various factors including volatile anaesthetics. These effects have to be considered in order to give correct interpretations of the obtained data. Visual evoked potentials (VEP) and auditory evoked potentials (AEP) will show strong alterations under general anaesthesia whereas brainstem auditory evoked potentials (BAEP) are slightly affected. The effects of nitrous oxide, halothane, enflurane, and isoflurane on somatosensory evoked potentials (SEP) after median nerve stimulation were studied in 35 healthy adult patients. pCO2 and tympanic membrane temperature were held constant. Simultaneous cervical and cortical SEP recording was performed using surface electrodes. After induction of anaesthesia SEP were recorded during normoventilation with 100% oxygen and after inhalation of 66.6% nitrous oxide. 10 patients received halothane at inspired concentrations of 0.5, 1.0, 1.5, and 2.0%. After nitrous oxide had been replaced by oxygen, halothane was reduced in steps of 0.5%. SEP were recorded at the end of each period (15 min). Equipotent doses of enflurane or isoflurane were administered to 15 and 10 patients, respectively. Nitrous oxide depressed early cortical SEP amplitude. Halothane, enflurane, and isoflurane caused dose dependent increases of latencies. Reduction of amplitude was most pronounced with isoflurane. Using high doses of enflurane in oxygen cortical SEP showed unusual high amplitudes associated with marked increases of latencies. Even under high concentrations of volatile anaesthetics cervical SEP were minimally affected. The effects of anaesthetic gases have to be considered when SEP are recorded intraoperatively.

  12. Vestibular-evoked myogenic potentials. (United States)

    Colebatch, J G; Rosengren, S M; Welgampola, M S


    The vestibular-evoked myogenic potential (VEMP) is a short-latency potential evoked through activation of vestibular receptors using sound or vibration. It is generated by modulated electromyographic signals either from the sternocleidomastoid muscle for the cervical VEMP (cVEMP) or the inferior oblique muscle for the ocular VEMP (oVEMP). These reflexes appear to originate from the otolith organs and thus complement existing methods of vestibular assessment, which are mainly based upon canal function. This review considers the basis, methodology, and current applications of the cVEMP and oVEMP in the assessment and diagnosis of vestibular disorders, both peripheral and central. © 2016 Elsevier B.V. All rights reserved.

  13. Time Perception and Evoked Potentials (United States)


    ARI Research Note 88-69 0 MitnS.Ktohe U.0 ... Ann-r (. Time Perception and Evoked Potentials Paul FraisseDT ( Lfniversit6 Rene Descartes E LECTE...JOHNSON 00L, [N Technical Dicctojr Cmad Research accomplished under contract for the Department of the Army C. Universite Rene Descartes , Paris )r...ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT. TASK Labrato-ire de Psychologie Experimental AREA• WORK UNIT NUMBERS Universite Rene Descartes

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

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    Sato Daisuke


    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

  15. Modeling auditory evoked potentials to complex stimuli

    DEFF Research Database (Denmark)

    Rønne, Filip Munch

    The auditory evoked potential (AEP) is an electrical signal that can be recorded from electrodes attached to the scalp of a human subject when a sound is presented. The signal is considered to reflect neural activity in response to the acoustic stimulation and is a well established clinical...... clinically and in research towards using realistic and complex stimuli, such as speech, to electrophysiologically assess the human hearing. However, to interpret the AEP generation to complex sounds, the potential patterns in response to simple stimuli needs to be understood. Therefore, the model was used...... to simulate auditory brainstem responses (ABRs) evoked by classic stimuli like clicks, tone bursts and chirps. The ABRs to these simple stimuli were compared to literature data and the model was shown to predict the frequency dependence of tone-burst ABR wave-V latency and the level-dependence of ABR wave...

  16. Steady-state evoked potentials to study the processing of tactile and nociceptive somatosensory input in the human brain. (United States)

    Colon, E; Legrain, V; Mouraux, A


    The periodic presentation of a sensory stimulus induces, at certain frequencies of stimulation, a sustained electroencephalographic response of corresponding frequency, known as steady-state evoked potentials (SS-EP). In visual, auditory and vibrotactile modalities, studies have shown that SS-EP reflect mainly activity originating from early, modality-specific sensory cortices. Furthermore, it has been shown that SS-EP have several advantages over the recording of transient event-related brain potentials (ERP), such as a high signal-to-noise ratio, a shorter time to obtain reliable signals, and the capacity to frequency-tag the cortical activity elicited by concurrently presented sensory stimuli. Recently, we showed that SS-EP can be elicited by the selective activation of skin nociceptors and that nociceptive SS-EP reflect the activity of a population of neurons that is spatially distinct from the somatotopically-organized population of neurons underlying vibrotactile SS-EP. Hence, the recording of SS-EP offers a unique opportunity to study the cortical representation of nociception and touch in humans, and to explore their potential crossmodal interactions. Here, (1) we review available methods to achieve the rapid periodic stimulation of somatosensory afferents required to elicit SS-EP, (2) review previous studies that have characterized vibrotactile and nociceptive SS-EP, (3) discuss the nature of the recorded signals and their relationship with transient event-related potentials and (4) outline future perspectives and potential clinical applications of this technique.

  17. Acute stress alters auditory selective attention in humans independent of HPA: a study of evoked potentials.

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    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

  18. Ocular Vestibular Evoked Myogenic Potentials

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    Felipe, Lilian


    Full Text Available Introduction Diagnostic testing of the vestibular system is an essential component of treating patients with balance dysfunction. Until recently, testing methods primarily evaluated the integrity of the horizontal semicircular canal, which is only a portion of the vestibular system. Recent advances in technology have afforded clinicians the ability to assess otolith function through vestibular evoked myogenic potential (VEMP testing. VEMP testing from the inferior extraocular muscles of the eye has been the subject of interest of recent research. Objective To summarize recent developments in ocular VEMP testing. Results Recent studies suggest that the ocular VEMP is produced by otolith afferents in the superior division of the vestibular nerve. The ocular VEMP is a short latency potential, composed of extraocular myogenic responses activated by sound stimulation and registered by surface electromyography via ipsilateral otolithic and contralateral extraocular muscle activation. The inferior oblique muscle is the most superficial of the six extraocular muscles responsible for eye movement. Therefore, measurement of ocular VEMPs can be performed easily by using surface electrodes on the skin below the eyes contralateral to the stimulated side. Conclusion This new variation of the VEMP procedure may supplement conventional testing in difficult to test populations. It may also be possible to use this technique to evaluate previously inaccessible information on the vestibular system.

  19. An Application of Motor Evoked Potential (MEP) Method to Analyzing Human Motor Learning


    志村, 邦義; 矢作, 晋; 笠井,達哉


    Until recently, drastic approach of motor learning in intact humans was not possible. The introduction of noninvasive techniques to stimulate the motor cortex in the present review permitted the testing and investigation of cortical motor outflow related to mechanisms in human motor learning. Human mapping studies, previously performed only during surgical procedures on patients with neurological disorders, can now be done with minimal discomfort. In the present brief review, therefore, we ha...

  20. [Intraoperative Visual Evoked Potential Monitoring]. (United States)

    Hayashi, Hironobu; Kawaguchi, Masahiko


    Visual evoked potential (VEP) is recorded from the back of the head, which is elicited by retinal stimulation transmitted through optic nerve, optic chiasm, optic tract lateral geniculate body, optic radiation and finally cortical visual area. VEP monitoring did not prevail since 1990s because marked intra-individual difference and instability of VEP recording limited the clinical usefulness under inhalation anesthetic management and techniques of VEP monitoring at the time. However, recent advances in techniques including a new light-stimulating device consisting of high-luminosity LEDs and induction of electroretinography to ascertain the arrival of the stimulus at the retina provided better conditions for stable VEP recording under general anesthesia. In addition, the introduction of total intravenous anesthesia using propofol is important for the successful VEP recordings because inhaled anesthetics have suppressive effect on VEP waveform. Intraoperative VEP has been considered to monitor the functional integrity of visual function during neurosurgical procedures, in which the optic pathway is at a risk of injury. Intraoperative VEP monitoring may allow us to detect reversible damage to the visual pathway intraoperatively and enable us to prevent permanent impairment.

  1. Short-Latency Median-Nerve Somatosensory-Evoked Potentials and Induced Gamma-Oscillations in Humans (United States)

    Fukuda, Miho; Nishida, Masaaki; Juhasz, Csaba; Muzik, Otto; Sood, Sandeep; Chugani, Harry T.; Asano, Eishi


    Recent studies have suggested that cortical gamma-oscillations are tightly linked with various forms of physiological activity. In the present study, the dynamic changes of intracranially recorded median-nerve somatosensory-evoked potentials (SEPs) and somatosensory-induced gamma-oscillations were animated on a three-dimensional MR image, and the…

  2. Assessing the Quality of Steady-state Visual-evoked Potentials for Moving Humans Using a Mobile Electroencephalogram Headset

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    Yuan-Pin eLin


    Full Text Available Recent advances in mobile electroencephalogram (EEG systems, featuring non-prep dry electrodes and wireless telemetry, have urged the needs of mobile brain-computer interfaces (BCIs for applications in our daily life. Since the brain may behave differently while people are actively situated in ecologically-valid environments versus highly-controlled laboratory environments, it remains unclear how well the current laboratory-oriented BCI demonstrations can be translated into operational BCIs for users with naturalistic movements. Understanding inherent links between natural human behaviors and brain activities is the key to ensuring the applicability and stability of mobile BCIs. This study aims to assess the quality of steady-state visual-evoked potentials (SSVEPs, which is one of promising channels for functioning BCI systems, recorded using a mobile EEG system under challenging recording conditions, e.g., walking. To systemati-cally explore the effects of walking locomotion on the SSVEPs, this study instructed subjects to stand or walk on a treadmill running at speeds of 1, 2, and 3 mile (s per hour (MPH while con-currently perceiving visual flickers (11 and 12 Hz. Empirical results of this study showed that the SSVEP amplitude tended to deteriorate when subjects switched from standing to walking. Such SSVEP suppression could be attributed to the walking locomotion, leading to distinctly deteriorated SSVEP detectability from standing (84.87±13.55% to walking (1 MPH: 83.03±13.24%, 2 MPH: 79.47±13.53%, and 3 MPH: 75.26±17.89%. These findings not only demonstrated the applicability and limitations of SSVEPs recorded from freely behaving humans in realistic environments, but also provide useful methods and techniques for boosting the translation of the BCI technology from laboratory demonstrations to practical applications.

  3. Evoked potentials in neuroinfections in children

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    V. N. Komantsev


    Full Text Available We present the results of the neurophysiological study in which 95 children with viral encephalitis and 30 children with meningitis (age from 2 up to 17 years undergo evoked potentials investigation. Some specific features of evoked potentials in neuroinfections have been shown to correlate with the course of disease and the age of the patients. We give a description of a logistic model of predicting outcomes in such patients by complex diagnostic method. We have found that evoked potentials may be successfully implemented in correcting the therapeutic strategies. Study of evoked potentials in neuroinfections in children can define the severity and extent of lesions and help to identify subclinical dysfunction and monitor the recovery processes under the therapy.

  4. Visual Evoked Potentials in Rett Syndrome

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    J. Gordon Millichap


    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.

  5. Dissociation of the pathways mediating ipsilateral and contralateral motor-evoked potentials in human hand and arm muscles (United States)

    Ziemann, Ulf; Ishii, Kenji; Borgheresi, Alessandra; Yaseen, Zaneb; Battaglia, Fortunato; Hallett, Mark; Cincotta, Massimo; Wassermann, Eric M


    Growing evidence points toward involvement of the human motor cortex in the control of the ipsilateral hand. We used focal transcranial magnetic stimulation (TMS) to examine the pathways of these ipsilateral motor effects.Ipsilateral motor-evoked potentials (MEPs) were obtained in hand and arm muscles of all 10 healthy adult subjects tested. They occurred in the finger and wrist extensors and the biceps, but no response or inhibitory responses were observed in the opponens pollicis, finger and wrist flexors and the triceps.The production of ipsilateral MEPs required contraction of the target muscle. The threshold TMS intensity for ipsilateral MEPs was on average 1.8 times higher, and the onset was 5.7 ms later (in the wrist extensor muscles) compared with size-matched contralateral MEPs.The corticofugal pathways of ipsilateral and contralateral MEPs could be dissociated through differences in cortical map location and preferred stimulating current direction.Both ipsi- and contralateral MEPs in the wrist extensors increased with lateral head rotation toward, and decreased with head rotation away from, the side of the TMS, suggesting a privileged input of the asymmetrical tonic neck reflex to the pathway of the ipsilateral MEP.Large ipsilateral MEPs were obtained in a patient with complete agenesis of the corpus callosum.The dissociation of the pathways for ipsilateral and contralateral MEPs indicates that corticofugal motor fibres other than the fast-conducting crossed corticomotoneuronal system can be activated by TMS. Our data suggest an ipsilateral oligosynaptic pathway, such as a corticoreticulospinal or a corticopropriospinal projection as the route for the ipsilateral MEP. Other pathways, such as branching of corticomotoneuronal axons, a transcallosal projection or a slow-conducting monosynaptic ipsilateral pathway are very unlikely or can be excluded. PMID:10420023

  6. Origin of facilitation of motor-evoked potentials after paired magnetic stimulation: direct recording of epidural activity in conscious humans. (United States)

    Di Lazzaro, V; Pilato, F; Oliviero, A; Dileone, M; Saturno, E; Mazzone, P; Insola, A; Profice, P; Ranieri, F; Capone, F; Tonali, P A; Rothwell, J C


    A magnetic transcranial conditioning stimulus given over the motor cortex at intensities below active threshold for obtaining motor-evoked potentials (MEPs) facilitates EMG responses evoked at rest in hand muscles by a suprathreshold magnetic stimulus given 10-25 ms later. This is known as intracortical facilitation (ICF). We recorded descending volleys produced by single and paired magnetic motor cortex stimulation through high cervical epidural electrodes implanted for pain relief in six conscious patients. At interstimulus intervals (ISIs) of 10 and 15 ms, although MEP was facilitated, there was no change in the amplitude or number of descending volleys. An additional I wave sometimes was observed at 25 ms ISI. In one subject, we also evaluated the effects of reversing the direction of the induced current in the brain. At 10 ms ISI, the facilitation of the MEPs disappeared and was replaced by slight suppression; at 2 ms ISI, there was a pronounced facilitation of epidural volleys. Subsequent experiments on healthy subjects showed that a conditioning stimulus capable of producing ICF of MEPs had no effect on the EMG response evoked by transmastoidal electrical stimulation of corticospinal tract. We conclude that ICF occurs because either 1) the conditioning stimulus has a (thus far undetected) effect on spinal cord excitability that increases its response to the same amplitude test volley or 2) that it can alter the composition (but not the amplitude) of the descending volleys set up by the test stimulus such that a larger proportion of the activity is destined for the target muscle.


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    A. A. Sazgar


    Full Text Available It has been shown recently that loud clicks evoke myogenic potentials in the tonically contracting sternocleidomastoid muscles. Studies have suggested that these potentials are of vestibular origin, especially of the saccule and inferior vestibular nerve. A pilot study was undertaken in our hospital to record vestibular evoked myogenic potentials (VEMP for the first time in Iran. Eighteen healthy volunteers (32 ears without history of otologic or vestibular disorders were subjected to the VEMP test. Twenty-one patients (26 ears with unilateral (6 patients and bilateral (5 patients high frequency sensorineural hearing loss with unknown etiology, acoustic neuroma (1 patient, Meniere’s disease (4 patients and unilateral low frequency sensorineural hearing loss without vestibular complaint (5 patients were also enrolled in this study. VEMP response to clicks was obtained from 84.4% of ears of healthy subjects. These subjects demonstrated short latency waves to click stimuli during tonic neck flexor activation. Mean latencies of first positive (p13 and first negative (n23 potentials in healthy subjects were 12.45 ± 1.9 ms and 20.8 ± 3.5 ms, respectively. Median latencies of these two potentials were 12.1 and 19.3 ms, respectively. We could record VEMP in 5 patients with unilateral and all patients with high and low frequency sensorineural hearing loss without vestibular complaint. In the patient with acoustic neuroma VEMP was absent on the affected side. This technique may offer a new method to evaluate otolith and sacculocollic pathways in human.

  8. Color Evoked Potentials in Adults and Infants. (United States)

    White, Carroll T.; And Others

    This paper discusses recent studies of the adult visual evoked potential (VEP) which have indicated that specific components of the complex waveform obtained are related to the three basic color processes, and that these components interact in ways that seem to agree with opponent-colors phenomena. The components identified as being related to the…

  9. Intraoperative monitoring of evoked potentials. (United States)

    Raudzens, P A


    Sensory EPs were recorded intraoperatively in 173 neurosurgical procedures (71 VEPs, 66 BAEPs, and 31 SSEPs) to evaluate the utility of this technique. EPs could be safely recorded in all cases, but the yield of useful results varied with each sensory modality. BAEPs were recorded reliably in 100% of the cases and intraoperative latency changes accurately predicted postoperative hearing deficits in 10%. Potential hearing deficits were detected in another 15%. BAEP changes were associated with brainstem dysfunction in only one case. VEP changes were difficult to interpret intraoperatively because of contamination by a high degree of variability and both false negative and false positive results. Changes in VEP amplitudes related to surgical manipulation of the optic chiasm were only suggested. SSEP changes were recorded reliably in only 75% of the cases and no correlations between SSEP changes and postoperative sensory function were established. Again, intraoperative amplitude attenuation of the SSEP waveform with surgical manipulation only suggested a potential sensory deficit. Intraoperative EP monitoring is a valuable technique that provides a functional analysis of the sensory nervous system during surgical procedures. Specific sensory stimuli and improved data analysis will increase the utility of this CNS monitor.

  10. [Effect of sleep deprivation on visual evoked potentials and brain stem auditory evoked potentials in epileptics]. (United States)

    Urumova, L T; Kovalenko, G A; Tsunikov, A I; Sumskiĭ, L I


    The article reports on the first study of the evoked activity of the brain in epileptic patients (n = 20) following sleep deprivation. An analysis of the data obtained has revealed a tendency to the shortening of the peak latent intervals of visual evoked potentials in the range of 100-200 mu sec and the V component and the interpeak interval III-V of evoked auditory trunk potentials in patients with temporal epilepsy. The phenomenon may indicate the elimination of stabilizing control involving the specific conductive pathways and, possibly, an accelerated conduction of a specific sensor signal.

  11. Early visual evoked potentials in callosal agenesis. (United States)

    Barr, Melodie S; Hamm, Jeff P; Kirk, Ian J; Corballis, Michael C


    Three participants with callosal agenesis and 12 neurologically normal participants were tested on a simple reaction time task, with visual evoked potentials collected using a high-density 128-channel system. Independent-components analyses were performed on the averaged visual evoked potentials to isolate the components of interest. Contrary to previous research with acallosals, evidence of ipsilateral activation was present in all 3 participants. Although ipsilateral visual components were present in all 4 unilateral conditions in the 2 related acallosal participants, in the 3rd, these were present only in the crossed visual field-hand conditions and not in the uncrossed conditions. Suggestions are made as to why these results differ from earlier findings and as to the neural mechanisms facilitating this ipsilateral activation.

  12. Auditory evoked potentials and multiple sclerosis


    Carla Gentile Matas; Sandro Luiz de Andrade Matas; Caroline Rondina Salzano de Oliveira; Isabela Crivellaro Gonçalves


    Multiple sclerosis (MS) is an inflammatory, demyelinating disease that can affect several areas of the central nervous system. Damage along the auditory pathway can alter its integrity significantly. Therefore, it is important to investigate the auditory pathway, from the brainstem to the cortex, in individuals with MS. OBJECTIVE: The aim of this study was to characterize auditory evoked potentials in adults with MS of the remittent-recurrent type. METHOD: The study comprised 25 individuals w...

  13. A joint sparse representation-based method for double-trial evoked potentials estimation. (United States)

    Yu, Nannan; Liu, Haikuan; Wang, Xiaoyan; Lu, Hanbing


    In this paper, we present a novel approach to solving an evoked potentials estimating problem. Generally, the evoked potentials in two consecutive trials obtained by repeated identical stimuli of the nerves are extremely similar. In order to trace evoked potentials, we propose a joint sparse representation-based double-trial evoked potentials estimation method, taking full advantage of this similarity. The estimation process is performed in three stages: first, according to the similarity of evoked potentials and the randomness of a spontaneous electroencephalogram, the two consecutive observations of evoked potentials are considered as superpositions of the common component and the unique components; second, making use of their characteristics, the two sparse dictionaries are constructed; and finally, we apply the joint sparse representation method in order to extract the common component of double-trial observations, instead of the evoked potential in each trial. A series of experiments carried out on simulated and human test responses confirmed the superior performance of our method.

  14. Recording and assessment of evoked potentials with electrode arrays. (United States)

    Miljković, N; Malešević, N; Kojić, V; Bijelić, G; Keller, T; Popović, D B


    In order to optimize procedure for the assessment of evoked potentials and to provide visualization of the flow of action potentials along the motor systems, we introduced array electrodes for stimulation and recording and developed software for the analysis of the recordings. The system uses a stimulator connected to an electrode array for the generation of evoked potentials, an electrode array connected to the amplifier, A/D converter and computer for the recording of evoked potentials, and a dedicated software application. The method has been tested for the assessment of the H-reflex on the triceps surae muscle in six healthy humans. The electrode array with 16 pads was positioned over the posterior aspect of the thigh, while the recording electrode array with 16 pads was positioned over the triceps surae muscle. The stimulator activated all the pads of the stimulation electrode array asynchronously, while the signals were recorded continuously at all the recording sites. The results are topography maps (spatial distribution of evoked potentials) and matrices (spatial visualization of nerve excitability). The software allows the automatic selection of the lowest stimulation intensity to achieve maximal H-reflex amplitude and selection of the recording/stimulation pads according to predefined criteria. The analysis of results shows that the method provides rich information compared with the conventional recording of the H-reflex with regard the spatial distribution.

  15. Evoked potentials in pediatric cerebral malaria

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    Minal Bhanushali


    Full Text Available Cortical evoked potentials (EP provide localized data regarding brain function and may offer prognostic information and insights into the pathologic mechanisms of malariamediated cerebral injury. As part of a prospective cohort study, we obtained somatosensory evoked potentials (SSEPs and brainstem auditory EPs (AEPs within 24 hours of admission on 27 consecutive children admitted with cerebral malaria (CM. Children underwent follow-up for 12 months to determine if they had any long term neurologic sequelae. EPs were obtained in 27 pediatric CM admissions. Two children died. Among survivors followed an average of 514 days, 7/25 (28.0% had at least one adverse neurologic outcome. Only a single subject had absent cortical EPs on admission and this child had a good neurologic outcome. Among pediatric CM survivors, cortical EPs are generally intact and do not predict adverse neurologic outcomes. Further study is needed to determine if alterations in cortical EPs can be used to predict a fatal outcome in CM.

  16. Long Latency Auditory Evoked Potentials during Meditation. (United States)

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


    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.

  17. Auditory evoked potentials in postconcussive syndrome. (United States)

    Drake, M E; Weate, S J; Newell, S A


    The neuropsychiatric sequelae of minor head trauma have been the source of controversy. Most clinical and imaging studies have shown no alteration after concussion, but neuropsychological and neuropathological abnormalities have been reported. Some changes in neurophysiologic diagnostic tests have been described in postconcussive syndrome. We recorded middle latency auditory evoked potentials (MLR) and slow vertex responses (SVR) in 20 individuals with prolonged cognitive difficulties, behavior changes, dizziness, and headache after concussion. MLR is utilized alternating polarity clicks presented monaurally at 70 dB SL at 4 per second, with 40 dB contralateral masking. Five hundred responses were recorded and replicated from Cz-A1 and Cz-A2, with 50 ms. analysis time and 20-1000 Hz filter band pass. SVRs were recorded with the same montage, but used rarefaction clicks, 0.5 Hz stimulus rate, 500 ms. analysis time, and 1-50 Hz filter band pass. Na and Pa MLR components were reduced in amplitude in postconcussion patients. Pa latency was significantly longer in patients than in controls. SVR amplitudes were longer in concussed individuals, but differences in latency and amplitude were not significant. These changes may reflect posttraumatic disturbance in presumed subcortical MLR generators, or in frontal or temporal cortical structures that modulate them. Middle and long-latency auditory evoked potentials may be helpful in the evaluation of postconcussive neuropsychiatric symptoms.

  18. Electrical high-frequency stimulation of the human thoracolumbar fascia evokes long-term potentiation-like pain amplification. (United States)

    Schilder, Andreas; Magerl, Walter; Hoheisel, Ulrich; Klein, Thomas; Treede, Rolf-Detlef


    Nociceptive long-term potentiation, a use dependent increase in synaptic efficacy in the dorsal horn of the spinal cord is thought to contribute to the development of persistent pain states. So far, no study has analyzed the effects of high-frequency stimulation (HFS) of afferents from deep tissues (muscle and fascia) on pain perception in the back in humans. In 16 healthy volunteers, the multifidus muscle and the overlying thoracolumbar fascia were stimulated with electrical high-frequency pulses (5 × 100 pulses at 100 Hz) through bipolar concentric needle electrodes placed at lumbar level (L3/L4). Electrical pain thresholds were lower (P fascia compared with muscle stimulation (P fascia, from 8 to 12 numerical rating scale for muscle; both P Fascia HFS increased fascia pain ratings 2.17 times compared with the unconditioned control site (P fascia by 20% (P 60 minutes post-HFS, potentiation by fascia HFS was similar to that of skin HFS. These findings show that the spinal input from the fascia can induce long-term changes in pain sensitivity for at least 60 minutes making it a candidate potentially contributing to nonspecific low back pain.

  19. New perspectives on vestibular evoked myogenic potentials. (United States)

    Rosengren, Sally M; Kingma, Herman


    Although the vestibular evoked myogenic potential (VEMP) measured from the cervical muscles (cVEMP, cervical VEMP) is well described and has documented clinical utility, its analogue recorded from the extraocular muscles (oVEMP, ocular VEMP) has been described only recently and is currently emerging as an additional test of otolith function. This review will, therefore, summarize recent developments in VEMP research with a focus on the oVEMP. Recent studies suggest that the oVEMP is produced by otolith afferents in the superior vestibular nerve division, whereas the cVEMP evoked by sound is thought to be an inferior vestibular nerve reflex. Correspondingly, the oVEMP correlates better with caloric and subjective visual vertical tests than sound-cVEMPs. cVEMPs are more complicated than often thought, as shown by the presence of crossed responses and conflicting results of recent vibration studies. Altered inner ear mechanics produced by the vestibular diseases superior semicircular canal dehiscence and Ménière's disease lead to changes in the preferred frequency of the oVEMP and cVEMP. The oVEMP provides complementary diagnostic information to the cVEMP and is likely to be a useful addition to the diagnostic test battery in neuro-otology.

  20. Visual evoked potentials in rubber factory workers. (United States)

    Tandon, O P; Kumar, V


    Pattern reversal visual evoked potentials (pVEP) were studied in 39 male rubber factory workers in the age range of 18-55 years and 20 control subjects (aged 18-46 years) not exposed to the rubber factory environment. Results revealed that 20 (51%) rubber factory workers had abnormal latencies of wave P1 (dominant component of pVEP) as per accepted criteria of 99% tolerance limit set for the control group (i.e. any value above mean +3 SD of control was considered abnormal). The section-wise per cent distribution of abnormalities was vulcanization (83%), tubing (75%), calendering (60%), loading (38%) and mixing (14%). This study provides electrophysiological evidence that rubber factory environments affect the conduction processes in optical pathways from their origin in the retina to striate cortex. However, this study has its limitations in not identifying the specific chemical(s) causing these changes in VEP.

  1. Resting Heart Rate and Auditory Evoked Potential

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    Simone Fiuza Regaçone


    Full Text Available The objective of this study was to evaluate the association between rest heart rate (HR and the components of the auditory evoked-related potentials (ERPs at rest in women. We investigated 21 healthy female university students between 18 and 24 years old. We performed complete audiological evaluation and measurement of heart rate for 10 minutes at rest (heart rate monitor Polar RS800CX and performed ERPs analysis (discrepancy in frequency and duration. There was a moderate negative correlation of the N1 and P3a with rest HR and a strong positive correlation of the P2 and N2 components with rest HR. Larger components of the ERP are associated with higher rest HR.

  2. Chirp-modulated visual evoked potential as a generalization of steady state visual evoked potential (United States)

    Tu, Tao; Xin, Yi; Gao, Xiaorong; Gao, Shangkai


    Visual evoked potentials (VEPs) are of great concern in cognitive and clinical neuroscience as well as in the recent research field of brain-computer interfaces (BCIs). In this study, a chirp-modulated stimulation was employed to serve as a novel type of visual stimulus. Based on our empirical study, the chirp stimuli visual evoked potential (Chirp-VEP) preserved frequency features of the chirp stimulus analogous to the steady state evoked potential (SSVEP), and therefore it can be regarded as a generalization of SSVEP. Specifically, we first investigated the characteristics of the Chirp-VEP in the time-frequency domain and the fractional domain via fractional Fourier transform. We also proposed a group delay technique to derive the apparent latency from Chirp-VEP. Results on EEG data showed that our approach outperformed the traditional SSVEP-based method in efficiency and ease of apparent latency estimation. For the recruited six subjects, the average apparent latencies ranged from 100 to 130 ms. Finally, we implemented a BCI system with six targets to validate the feasibility of Chirp-VEP as a potential candidate in the field of BCIs.

  3. [Intraoperative monitoring of visual evoked potentials]. (United States)

    Sasaki, Tatsuya; Ichikawa, Tsuyoshi; Sakuma, Jun; Suzuki, Kyouichi; Matsumoto, Masato; Itakura, Takeshi; Kodama, Namio; Murakawa, Masahiro


    Our success rate of intraoperative monitoring of visual evoked potential (VEP) had been approximately 30% in the past. In order to improve recording rate of intraoperative VEP, we developed a new stimulating device using high power light emitting diodes. Electroretinogram was simultaneously recorded to understand whether flash stimulation reached the retina. In addition, total venous anesthesia with propofol was used to avoid the adverse effect of inhalation anesthesia. We report the results after introduction of these improvements. Intraoperative monitoring of VEP was attempted in 35 cases. We evaluated success rate of VEP recording, correlation between VEP findings and postoperative visual function, and reasons why recording was not successful. Stable and reproducible waveforms were obtained in 59 sides (84%). Two cases, whose VEP deteriorated intraoperatively, developed postoperative visual disturbance: In 11 sides (16%), stable waveforms were not obtained. There were two main causes. In 8 sides out of 11, the cause was attributed to pre-existing severe visual disturbance. In these 8 sides, VEP in the awake state was not recordable or was recordable, but with very low amplitudes under 1 microV. In the other 3 sides, the cause was attributed to movement of a stimulating device by reflecting the fronto-temporal scalp flap. In conclusion, the successful recording rate was increased to 84% from approximately 30%, after introduction of various trials. We need further improvement in recording intraoperative VEP to establish a reliable intraoperative monitoring method for VEP.

  4. Evoked Effective Connectivity of the Human Neocortex


    Entz, László; Tóth, Emília; Keller, Corey J.; Bickel, Stephan; Groppe, David M.; Fabó, Dániel; Kozák, Lajos R.; Eroőss, Loránd; Ulbert, István; Mehta, Ashesh D.


    The role of cortical connectivity in brain function and pathology is increasingly being recognized. While in vivo magnetic resonance imaging studies have provided important insights into anatomical and functional connectivity, these methodologies are limited in their ability to detect electrophysiological activity and the causal relationships that underlie effective connectivity. Here, we describe results of cortico-cortical evoked potential (CCEP) mapping using single pulse electrical stimul...

  5. Multimodal evoked potential abnormalities in patients with Wilson's disease

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    Ilić Tihomir V.


    Full Text Available The aim of this study was to investigate the involvement of the following functional systems: somatosensory evoked potentials (SSEP, visual evoked potentials (VEP, and event related potentials (ERP, in twenty patients with Wilson's disease (WD. VEP and SSEP abnormalities were discovered in S patients respectively (40%, whereas ERP were either absent or, in the case of 10 patients (50%, had significantly prolonged P-300 latencies. Taken together, at least one evoked potential abnormality was discovered in 17 patients (85%]. Only in 3 patients (15%, involving either the isolated hepatic type of disease or short illness duration of the neurological type, were normal evoked potential findings observed. Our findings suggest the usefulness of multimodal evoked potential abnormalities in the evaluation of subclinical manifestations in patients with WD.

  6. Potenciais miogênicos evocados vestibulares: metodologias de registro em homens e cobaias Vestibular evoked myogenic potential: recording methods in humans and guinea pigs

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    Aline Cabral de Oliveira


    Full Text Available O potencial miogênico evocado vestibular (VEMP é um teste clínico que avalia a função vestibular através de um reflexo vestíbulo-cervical inibitório captado nos músculos do corpo em resposta à estimulação acústica de alta intensidade. OBJETIVO: Verificar e analisar os diversos métodos de registro dos potenciais miogênicos evocados vestibulares no homem e em cobaias. MATERIAL E MÉTODO: Realizou-se busca eletrônica nas bases de dados MEDLINE, LILACS, SCIELO e COCHRANE. RESULTADOS: Foram verificadas divergências quanto às formas de registro dos potenciais miogênicos evocados vestibulares, relacionadas com os seguintes fatores: posição do paciente no momento do registro, tipo de estímulo sonoro utilizado (clicks ou tone bursts, parâmetros para a promediação dos estímulos (intensidade, freqüência, tempo de apresentação, filtros, ganho de amplificação das respostas e janelas para captação dos estímulos, tipo de fone utilizado e forma de apresentação dos estímulos (monoaural ou binaural, ipsi ou contralateral. CONCLUSÃO: Não existe consenso na literatura quanto ao melhor método de registro dos potenciais evocados miogênicos vestibulares, havendo necessidade de pesquisas mais específicas para comparação entre estes registros e a definição de um modelo padrão para a utilização na prática clínica.The vestibular evoked myogenic potential (VEMP is a clinical test that assess the vestibular function by means of an inhibitory vestibulo-neck reflex, recorded in body muscles in response to high intensity acoustic stimuli. AIM: To check and analyze the different methods used to record VEMPs in humans and in guinea pigs. MATERIALS AND METHODS: We researched the following databases: MEDLINE, LILACS, SCIELO and COCHRANE. RESULTS: we noticed discrepancies in relation to the ways used to record the vestibular evoked myogenic potentials in relation to the following factors: patient position at the time of recording

  7. Auditory evoked potentials in peripheral vestibular disorder individuals

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    Matas, Carla Gentile


    Full Text Available Introduction: The auditory and vestibular systems are located in the same peripheral receptor, however they enter the CNS and go through different ways, thus creating a number of connections and reaching a wide area of the encephalon. Despite going through different ways, some changes can impair both systems. Such tests as Auditory Evoked Potentials can help find a diagnosis when vestibular alterations are seen. Objective: describe the Auditory Evoked Potential results in individuals complaining about dizziness or vertigo with Peripheral Vestibular Disorders and in normal individuals having the same complaint. Methods: Short, middle and long latency Auditory Evoked Potentials were performed as a transversal prospective study. Conclusion: individuals complaining about dizziness or vertigo can show some changes in BAEP (Brainstem Auditory Evoked Potential, MLAEP (Medium Latency Auditory Evoked Potential and P300.

  8. Cortical evoked potentials recorded from the guinea pig without averaging. (United States)

    Walloch, R A


    Potentials evoked by tonal pulses and recorded with a monopolar electrode on the pial surface over the auditory cortex of the guinea pig are presented. These potentials are compared with average potentials recorded in previous studies with an electrode on the dura. The potentials recorded by these two techniques have similar waveforms, peak latencies and thresholds. They appear to be generated within the same region of the cerebral cortex. As can be expected, the amplitude of the evoked potentials recorded from the pial surface is larger than that recorded from the dura. Consequently, averaging is not needed to extract the evoked potential once the dura is removed. The thresholds for the evoked cortical potential are similar to behavioral thresholds for the guinea pig at high frequencies; however, evoked potential thresholds are eleveate over behavioral thresholds at low frequencies. The removal of the dura and the direct recording of the evoked potential appears most appropriate for acute experiments. The recording of an evoked potential with dura electrodes empploying averaging procedures appears most appropriate for chronic studies.

  9. [Brainstem auditory evoked potentials and somatosensory evoked potentials in Chiari malformation]. (United States)

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


    Introduccion. La malformacion de Chiari (MC) incluye una serie de anomalias congenitas que tienen como comun denominador la ectopia de las amigdalas del cerebelo por debajo del foramen magno, lo que puede condicionar fenomenos compresivos del troncoencefalo, la medula espinal alta y los nervios craneales, alterando las respuestas de los potenciales evocados auditivos del tronco cerebral (PEATC) y de los potenciales evocados somatosensoriales (PESS). Sin embargo, las indicaciones de ambas exploraciones en las MC han sido motivo de estudio en un numero limitado de publicaciones, centradas en series cortas y heterogeneas de pacientes. Objetivo. Revisar los hallazgos de los PEATC y los PESS en los estudios publicados en pacientes con MC tipo 1 (MC-1) o tipo 2 (MC-2), y su indicacion en el diagnostico, tratamiento y seguimiento, especialmente en la MC-1. Desarrollo. Es un estudio de revision realizado mediante analisis de los estudios publicados en Medline desde 1966, localizados mediante PubMed, utilizando combinaciones de las palabras clave 'Chiari malformation', 'Arnold-Chiari malformation', 'Chiari type 1 malformation', 'Arnold-Chiari type 1 malformation', 'evoked potentials', 'brainstem auditory evoked potentials' y 'somatosensory evoked potentials', asi como informacion de pacientes con MC-1 valorados en los servicios de neurocirugia y neurofisiologia clinica del Hospital Universitari Vall d'Hebron. Conclusiones. Los hallazgos mas comunes de los PESS son la reduccion en la amplitud cortical para el nervio tibial posterior, la reduccion o ausencia del potencial cervical del nervio mediano y el aumento del intervalo N13-N20. En el caso de los PEATC, los hallazgos mas frecuentes descritos son el aumento del intervalo I-V y la alteracion periferica o coclear.

  10. Laser evoked potentials in carpal tunnel syndrome. (United States)

    de Tommaso, Marina; Libro, Giuseppe; Difruscolo, Olimpia; Sardaro, Michele; Serpino, Claudia; Calabrese, Rita; Vecchio, Eleonora; Livrea, Paolo


    The aim of this study was to evaluate the function of Adelta fibers at the hand level in patients with clinical symptoms of Carpal Tunnel Syndrome (CTS) using CO(2) laser evoked potentials (LEPs), in light of the intensity and distribution of sensory symptoms and pain. Thirty-four CTS outpatients (62 hands) were compared to 23 sex- and age-matched control subjects (46 hands). The periungueal skin of the first, second, third and fifth fingers, and the dorsum of the hands were stimulated in random order. The latency and amplitude of the N2, P2 and N1 components were evaluated with respect to the Nerve Conduction Study (NCS) data, clinical scales, pain intensity and glove-like symptoms distribution. The amplitude of the N2-P2 complex was significantly reduced in CTS hands compared to normal hands after stimulation of the second and third fingers, even in patients with mild nerve conduction impairment. No significant fifth finger LEP abnormalities were found in patients with glove-like distribution symptoms. The N2-P2 amplitude at the second and third fingers was positively correlated with the severity of sensory symptoms. The involvement of median nerve Adelta fibers in CTS seems to be an early phenomenon, which concurs with the impairment of large motor and sensory afferents and is linked to the severity of the disease. The finding of reduced sensory symptoms in patients with severe thin afferents damage, may suggest a slight expression of central sensitisation phenomena in the advanced stage of CTS syndrome.

  11. Pudendal somatosensory evoked potentials in normal women

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    Geraldo A. Cavalcanti


    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.

  12. Evoked potentials and head injury. 1. Rating of evoked potential abnormality. (United States)

    Rappaport, M; Hall, K; Hopkins, H K; Belleza, T


    This paper describes a method for rating the degree of abnormality of auditory, visual and somatosensory evoked potential patterns in head injury (HI) patients. Criteria for judging degree of EP abnormality are presented that allow assessment of the extent and severity of subcortical and cortical dysfunction associated with traumatic brain damage. Interrater reliability data based upon blind ratings of normal and HI patients are presented and shown to be highly significant. Tables of normative values of peak latencies and amplitudes are given and illustrations of EP patterns of different degrees of abnormality are presented.

  13. Mind games : the effects of diazepam on Evoked Potentials

    NARCIS (Netherlands)

    Jongsma, Marie-Louise Albertien


    The electroencephalogram (EEG) represents the electrical activity of the brain. Evoked Potentials (EPs) are small voltage fluctuations in the EEG resulting from sensory, cognitive or motor evoked neural activity. Variations in the EP waveform may be caused by several factors. 1. By employing differe

  14. Electroretinography and Visual Evoked Potentials in Childhood Brain Tumor Survivors. (United States)

    Pietilä, Sari; Lenko, Hanna L; Oja, Sakari; Koivisto, Anna-Maija; Pietilä, Timo; Mäkipernaa, Anne


    This population-based cross-sectional study evaluates the clinical value of electroretinography and visual evoked potentials in childhood brain tumor survivors. A flash electroretinography and a checkerboard reversal pattern visual evoked potential (or alternatively a flash visual evoked potential) were done for 51 survivors (age 3.8-28.7 years) after a mean follow-up time of 7.6 (1.5-15.1) years. Abnormal electroretinography was obtained in 1 case, bilaterally delayed abnormal visual evoked potentials in 22/51 (43%) cases. Nine of 25 patients with infratentorial tumor location, and altogether 12 out of 31 (39%) patients who did not have tumors involving the visual pathways, had abnormal visual evoked potentials. Abnormal electroretinographies are rarely observed, but abnormal visual evoked potentials are common even without evident anatomic lesions in the visual pathway. Bilateral changes suggest a general and possibly multifactorial toxic/adverse effect on the visual pathway. Electroretinography and visual evoked potential may have clinical and scientific value while evaluating long-term effects of childhood brain tumors and tumor treatment.

  15. Auditory evoked potentials and vestibular evoked myogenic potentials in evaluation of brainstem lesions in multiple sclerosis. (United States)

    Ivanković, Anita; Nesek Mađarić, Vesna; Starčević, Katarina; Krbot Skorić, Magdalena; Gabelić, Tereza; Adamec, Ivan; Habek, Mario


    The aim of this study was to determine the roles of magnetic resonance imaging (MRI), auditory evoked potentials (AEP) and vestibular evoked myogenic potentials (VEMP) in the evaluation of brainstem involvement in multiple sclerosis (MS). Altogether 32 patients with the diagnosis of MS participated in the study. The following data was collected from all patients: age, gender, Expanded Disability Status Scale (EDSS) score, brainstem functional system score (BSFS) (part of the EDSS evaluating brainstem symptomatology), and involvement of the brainstem on the brain MRI. AEP and ocular VEMP (oVEMP) and cervical VEMP (cVEMP) were studied in all patients. BSFS, MRI, AEP, oVEMP and cVEMP involvement of the brainstem was evident in 9 (28.1%), 14 (43.8%), 7 (21.9%), 12 (37.5%) and 10 (31.0%) patients, respectively. None of the tests used showed statistically significant advantage in the detection of brainstem lesions. When combining oVEMP and cVEMP 18 (56.3%) patients showed brainstem involvement. This combination showed brainstem involvement in greater percentage than BSFS or AEP, with statistical significance (p=0.035 and p=0.007, respectively). VEMP is a reliable method in detection of brainstem involvement in MS. It is comparable with MRI, but superior to clinical examination or AEP. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Somatosensory Evoked Potential Findings in Ankylosing Spondylitis (United States)

    Cidem, Muharrem; Sahin, Zerrin; Aydin, Teoman; Aysal, Fikret


    Objective: Somatosensory evoked potential (SSEP) abnormalities were reported in patients with ankylosing spondylitis (AS). This study aimed to investigate SSEP abnormalities and its relation with clinical findings in AS patients. Materials and Methods: The study included 26 patients with AS and 17 age-matched health volunteers (Control for SSEP). Median nerve SSEP findings were normal in all AS cases. Results: However, delayed latency and/or very low amplitude of tibial nerve SSEP was found in 20 (76.9%) AS patients. There were significant correlations between tibial SSEP latency and disease duration (R=0.433 to 0.635). There was also an inverse correlation between tibial SSEP amplitude and disease duration (R=−0.429, p=0.047). Serum estradiol level, hip total bone mineral density, The Bath Ankylosing Spondylitis Functional Index (BASFI) score and Beck depression score were significantly lower in AS patients with SSEP abnormalities (37.3±10.8 pg/mL, 0.916±0.123 g/cm2, 35.0±27.9, 12.8±8.4, respectively) than in AS patients without SSEP abnormalities (53.7±12.3 pg/mL, 1.103±0.197 g/cm2, 64.8±15.5, 24.8±10.1, respectively). Conclusion: Significant inverse correlations between SSEP latencies and dehydroepiandrosterone sulphate (DHEAS) levels were found (R=−0.400 to −0.713). There were also significant inverse correlation between SSEP latencies and DHEAS/oestrogen index (R=−0.596 to −0.868), and between SSEP latencies and DHEAS/Progesterone index (R=−0.467 to −0.685). As a conclusion, this study indicates that tibial nerve SSEP abnormalities are common in patients with AS and there are significant correlations between clinical findings of AS and SSEP abnormalities. PMID:25610293

  17. Multiple Color Stimulus Induced Steady State Visual Evoked Potentials (United States)


    evoked potentials, multiple color, FFT, bispectrum I. INTRODUCTION Visual evoked potential ( VEP ) is the electrical response of...brain under visual stimulation, which can be recorded from the scalp over the visual cortex of the brain. A distinction is made between transient VEP ...and steady-state VEP (SSVEP) based on the stimulation frequencies. The former arises when the stimulation frequencies are less than 2 Hz. However

  18. Vestibular receptors contribute to cortical auditory evoked potentials. (United States)

    Todd, Neil P M; Paillard, Aurore C; Kluk, Karolina; Whittle, Elizabeth; Colebatch, James G


    Acoustic sensitivity of the vestibular apparatus is well-established, but the contribution of vestibular receptors to the late auditory evoked potentials of cortical origin is unknown. Evoked potentials from 500 Hz tone pips were recorded using 70 channel EEG at several intensities below and above the vestibular acoustic threshold, as determined by vestibular evoked myogenic potentials (VEMPs). In healthy subjects both auditory mid- and long-latency auditory evoked potentials (AEPs), consisting of Na, Pa, N1 and P2 waves, were observed in the sub-threshold conditions. However, in passing through the vestibular threshold, systematic changes were observed in the morphology of the potentials and in the intensity dependence of their amplitude and latency. These changes were absent in a patient without functioning vestibular receptors. In particular, for the healthy subjects there was a fronto-central negativity, which appeared at about 42 ms, referred to as an N42, prior to the AEP N1. Source analysis of both the N42 and N1 indicated involvement of cingulate cortex, as well as bilateral superior temporal cortex. Our findings are best explained by vestibular receptors contributing to what were hitherto considered as purely auditory evoked potentials and in addition tentatively identify a new component that appears to be primarily of vestibular origin.

  19. A Comprehensive Review on Methodologies Employed for Visual Evoked Potentials. (United States)

    Kothari, Ruchi; Bokariya, Pradeep; Singh, Smita; Singh, Ramji


    Visual information is fundamental to how we appreciate our environment and interact with others. The visual evoked potential (VEP) is among those evoked potentials that are the bioelectric signals generated in the striate and extrastriate cortex when the retina is stimulated with light which can be recorded from the scalp electrodes. In the current paper, we provide an overview of the various modalities, techniques, and methodologies which have been employed for visual evoked potentials over the years. In the first part of the paper, we cast a cursory glance on the historical aspect of evoked potentials. Then the growing clinical significance and advantages of VEPs in clinical disorders have been briefly described, followed by the discussion on the earlier and currently available methods for VEPs based on the studies in the past and recent times. Next, we mention the standards and protocols laid down by the authorized agencies. We then summarize the recently developed techniques for VEP. In the concluding section, we lay down prospective research directives related to fundamental and applied aspects of VEPs as well as offering perspectives for further research to stimulate inquiry into the role of visual evoked potentials in visual processing impairment related disorders.

  20. Event related potentials to digit learning: Tracking neurophysiologic changes accompanying recall performanceModelling of auditory evoked potentials of human sleep-wake states

    NARCIS (Netherlands)

    Jongsma, M.L.A.; Gerrits, N.J.H.M.; Rijn, C.M. van; Quiroga, R.Q.; Maes, J.H.R.


    The aim of this study was to track recall performance and event-related potentials (ERPs) across multiple trials in a digit-learning task. When a sequence is practiced by repetition, the number of errors typically decreases and a learning curve emerges. Until now, almost all ERP learning and memory

  1. Stimulator with arbitrary waveform for auditory evoked potentials

    Energy Technology Data Exchange (ETDEWEB)

    Martins, H R; Romao, M; Placido, D; Provenzano, F; Tierra-Criollo, C J [Universidade Federal de Minas Gerais (UFMG), Departamento de Engenharia Eletrica (DEE), Nucleo de Estudos e Pesquisa em Engenharia Biomedica NEPEB, Av. Ant. Carlos, 6627, sala 2206, Pampulha, Belo Horizonte, MG, 31.270-901 (Brazil)


    The technological improvement helps many medical areas. The audiometric exams involving the auditory evoked potentials can make better diagnoses of auditory disorders. This paper proposes the development of a stimulator based on Digital Signal Processor. This stimulator is the first step of an auditory evoked potential system based on the ADSP-BF533 EZ KIT LITE (Analog Devices Company - USA). The stimulator can generate arbitrary waveform like Sine Waves, Modulated Amplitude, Pulses, Bursts and Pips. The waveforms are generated through a graphical interface programmed in C++ in which the user can define the parameters of the waveform. Furthermore, the user can set the exam parameters as number of stimuli, time with stimulation (Time ON) and time without stimulus (Time OFF). In future works will be implemented another parts of the system that includes the acquirement of electroencephalogram and signal processing to estimate and analyze the evoked potential.

  2. Value of transcranial motor evoked potentials during spinal operations

    Institute of Scientific and Technical Information of China (English)


    @@ To the Editor: We read the interesting recent article by Ding et al1 concerning the value of somatosensory evoked potentials (SEPs) in the diagnosis and prognosis of cervical spondylotic myelopathy, as well as the usefulness of monitoring intraoperative potentials in terms of safety and predictive factors.


    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...

  4. [Evoked potentials in intracranial operations: current status and our experiences]. (United States)

    Nau, H E; Hess, W; Pohlen, G; Marggraf, G; Rimpel, J


    Intraoperative neuromonitoring, especially evoked potential monitoring, has gained interest in recent years for both the anesthesiologist evaluating cerebral function and the neurosurgeon wishing to avoid neuronal lesions during intracranial operations. Before evoked potential monitoring can be introduced as a routine method of intraoperative management, experience with this method particularly in intensive care units, is imperative. We recorded evoked potentials with the Compact Four (Nicolet) and Basis 8000 (Schwarzer Picker International) computer systems. Preoperative derivations should be done with the same apparatus used intraoperatively and parameters of peri- and intraoperative derivations should not be changed. The patient's head must be fixed in a Mayfield clamp in order to avoid artefacts during trepanation. The possible artefacts due to apparatus, patient, or anesthesia are summarized in the tables. The derivations of evoked potentials should be supervised by a person who is not involved in the anesthesia or the surgical procedure; this condition may change in the future with full automatization of the recording technique and alarms. Good communication between surgeon, anesthesiologist, and neurophysiological assistant is a prerequisite. The modality is chosen in accordance with the affected neuronal system: visual-evoked potential (VEP) monitoring in the management of processes affecting the visual pathway, brain stem auditory-(BAER) and somatosensory-evoked potential (SSEP) monitoring in lesions affecting these pathways, in particular space-occupying lesions of the posterior fossa. VEP monitoring may be useful, but we observed alterations of the responses without changes in the level of anesthesia or manipulation of the visual pathways. In space-occupying processes of the cerebellopontine angle, BAER could not be developed in nearly all cases because the large underlying tumor had caused the disappearance of waves II-V. In these cases SSEP monitoring

  5. Cortical evoked potentials to an auditory illusion: binaural beats. (United States)

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


    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.

  6. Temporal resolution in the hearing system and auditory evoked potentials

    DEFF Research Database (Denmark)

    Miller, Lee; Beedholm, Kristian


    3pAB5. Temporal resolution in the hearing system and auditory evoked potentials. Kristian Beedholm Institute of Biology,University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark,, Lee A. Miller Institute of Biology,University of Southern Denmark, Campusvej 55, 5230...... Odense M, Denmark, lee@biology.sdu.dkA popular type of investigation with auditory evoked potentials AEP consists of mapping the dependency of the envelope followingresponse to the AM frequency. This results in what is called the modulation rate transfer function MRTF. The physiologicalinterpretation...... of the MRTF is not straight forward, but is often used as a measure of the ability of the auditory system to encodetemporal changes. It is, however, shown here that the MRTF must depend on the waveform of the click-evoked AEP ceAEP, whichdoes not relate directly to temporal resolution. The theoretical...

  7. Characterization of Motor and Somatosensory Evoked Potentials in the Yucatan Micropig Using Transcranial and Epidural Stimulation. (United States)

    Benavides, Francisco D; Santamaria, Andrea J; Bodoukhin, Nikita; Guada, Luis G; Solano, Juan P; Guest, James D


    Yucatan micropigs have brain and spinal cord dimensions similar to humans and are useful for certain spinal cord injury (SCI) translational studies. Micropigs are readily trained in behavioral tasks, allowing consistent testing of locomotor loss and recovery. However, there has been little description of their motor and sensory pathway neurophysiology. We established methods to assess motor and sensory cortical evoked potentials in the anesthetized, uninjured state. We also evaluated epidurally evoked motor and sensory stimuli from the T6 and T9 levels, spanning the intended contusion injury epicenter. Response detection frequency, mean latency and amplitude values, and variability of evoked potentials were determined. Somatosensory evoked potentials were reliable and best detected during stimulation of peripheral nerve and epidural stimulation by referencing the lateral cortex to midline Fz. The most reliable hindlimb motor evoked potential (MEP) occurred in tibialis anterior. We found MEPs in forelimb muscles in response to thoracic epidural stimulation likely generated from propriospinal pathways. Cranially stimulated MEPs were easier to evoke in the upper limbs than in the hindlimbs. Autopsy studies revealed substantial variations in cortical morphology between animals. This electrophysiological study establishes that neurophysiological measures can be reliably obtained in micropigs in a time frame compatible with other experimental procedures, such as SCI and transplantation. It underscores the need to better understand the motor control pathways, including the corticospinal tract, to determine which therapeutics are suitable for testing in the pig model.

  8. Evaluation of Evoked Potentials to Dyadic Tones after Cochlear Implantation (United States)

    Sandmann, Pascale; Eichele, Tom; Buechler, Michael; Debener, Stefan; Jancke, Lutz; Dillier, Norbert; Hugdahl, Kenneth; Meyer, Martin


    Auditory evoked potentials are tools widely used to assess auditory cortex functions in clinical context. However, in cochlear implant users, electrophysiological measures are challenging due to implant-created artefacts in the EEG. Here, we used independent component analysis to reduce cochlear implant-related artefacts in event-related EEGs of…

  9. Cortical Auditory Evoked Potentials in Unsuccessful Cochlear Implant Users (United States)

    Munivrana, Boska; Mildner, Vesna


    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…


    NARCIS (Netherlands)



    Monitoring of median nerve somatosensory evoked potentials (SSEP) during surgery for a basilar artery aneurysm under moderate hypothermia revealed an unexpected loss of the first cortical peak. This was due to compression of the middle cerebral artery under the retractor during the surgical approach

  11. Asymmetric vestibular evoked myogenic potentials in unilateral Meniere patients

    NARCIS (Netherlands)

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


    Vestibular evoked myogenic potentials (VEMPs) were measured in 22 unilateral MeniSre patients with monaural and binaural stimulation with 250 and 500 Hz tone bursts. For all measurement situations significantly lower VEMP amplitudes were on average measured at the affected side compared to the unaff

  12. Cortical Auditory Evoked Potentials in Unsuccessful Cochlear Implant Users (United States)

    Munivrana, Boska; Mildner, Vesna


    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…

  13. Thermal grill conditioning: Effect on contact heat evoked potentials (United States)

    Jutzeler, Catherine R.; Warner, Freda M.; Wanek, Johann; Curt, Armin; Kramer, John L. K.


    The ‘thermal grill illusion’ (TGI) is a unique cutaneous sensation of unpleasantness, induced through the application of interlacing warm and cool stimuli. While previous studies have investigated optimal parameters and subject characteristics to evoke the illusion, our aim was to examine the modulating effect as a conditioning stimulus. A total of 28 healthy control individuals underwent three testing sessions on separate days. Briefly, 15 contact heat stimuli were delivered to the right hand dorsum, while the left palmar side of the hand was being conditioned with either neutral (32 °C), cool (20 °C), warm (40 °C), or TGI (20/40 °C). Rating of perception (numeric rating scale: 0–10) and evoked potentials (i.e., N1 and N2P2 potentials) to noxious contact heat stimuli were assessed. While cool and warm conditioning decreased cortical responses to noxious heat, TGI conditioning increased evoked potential amplitude (N1 and N2P2). In line with other modalities of unpleasant conditioning (e.g., sound, visual, and olfactory stimulation), cortical and possibly sub-cortical modulation may underlie the facilitation of contact heat evoked potentials. PMID:28079118

  14. 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.


    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

  15. Visual evoked potentials in patients after methanol poisoning

    Directory of Open Access Journals (Sweden)

    Pavel Urban


    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.

  16. Frequency tuning of the cervical vestibular-evoked myogenic potential (cVEMP) recorded from multiple sites along the sternocleidomastoid muscle in normal human subjects. (United States)

    Wei, Wei; Jeffcoat, Ben; Mustain, William; Zhu, Hong; Eby, Thomas; Zhou, Wu


    Frequency tuning of tone burst-evoked myogenic potentials recorded from the sternocleidomastoid muscle (cervical VEMP or cVEMP) is used clinically to assess vestibular function. Understanding the characteristics of cVEMP is important for improving the specificity of cVEMP testing in diagnosing vestibular deficits. In the present study, we analyzed the frequency tuning properties of the cVEMPs by constructing detailed tuning curves and examining their morphology and dependence on SCM tonic level, sound intensity, and recording site along the SCM. Here we report two main findings. First, by employing nine tone frequencies between 125 and 4,000 Hz, some tuning curves exhibited two distinct peaks, which cannot be modeled by a single mass spring system as previously suggested. Instead, the observed tuning is better modeled as linear summation of two mass spring systems, with resonance frequencies at ~300 and ~1,000 Hz. Peak frequency of cVEMP tuning curves was not affected by SCM tonic level, sound intensity, and location of recording site on the SCM. However, sharpness of cVEMP tuning was increased at lower sound intensities. Second, polarity of cVEMP responses recorded from the lower quarter of the SCM was reversed as compared to that at the two upper sites. While more studies are needed, these results suggest that cVEMP tuning is mediated through multiple generators with different resonance frequencies. Future studies are needed to explore implications of these results on development of selective VEMP tests and determine the nature of polarity inversion at the lower quarter of SCM.

  17. Ocular vestibular evoked myogenic potentials are abnormal in internuclear ophthalmoplegia. (United States)

    Rosengren, S M; Colebatch, J G


    The cervical vestibular evoked myogenic potential (cVEMP) is sensitive to lower brainstem lesions affecting the vestibulo-collic pathway. We wished to determine whether the ocular VEMP (oVEMP), a recently-described otolith-ocular reflex, is also abnormal in patients with brainstem lesions. We tested patients with internuclear ophthalmoplegia (INO), caused by a brainstem lesion in the medial longitudinal fasciculus (MLF), to investigate whether the oVEMP is abnormal in patients with a lesion of the otolith-ocular pathway. We describe a patient who developed a right INO during his first episode of demyelination, and report results from 12 additional patients, most of whom had multiple sclerosis. All subjects were stimulated with air-conducted tone bursts. cVEMPs and oVEMPs were measured using surface electrodes placed over the neck and beneath the eyes. Overall, oVEMPs showed significantly more abnormalities (69%) than cVEMPs (8%). Ocular VEMPs were absent with stimulation of 13/26 ears, significantly delayed in 5/26 cases and normal in only 8/26 cases. Ocular VEMPs are often abnormal in patients with multiple sclerosis who have an INO, while cVEMPs are usually normal. Ocular VEMPs provide a new, non-invasive method for examining central vestibular pathways in humans and are sensitive to lesions of the MLF. Copyright © 2010 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  18. Influence of a preceding auditory stimulus on evoked potential of the succeeding stimulus

    Institute of Scientific and Technical Information of China (English)

    WANG Mingshi; LIU Zhongguo; ZHU Qiang; LIU Jin; WANG Liqun; LIU Haiying


    In the present study, we investigated the influence of the preceding auditory stimulus on the auditory-evoked potential (AEP) of the succeeding stimuli, when the human subjects were presented with a pair of auditory stimuli. We found that the evoked potential of the succeeding stimulus was inhibited completely by the preceding stimulus, as the inter-stimulus interval (ISI) was shorter than 150 ms. This influence was dependent on the ISI of two stimuli, the shorter the ISI the stronger the influence would be. The inhibitory influence of the preceding stimulus might be caused by the neural refractory effect.

  19. Inferring regional brain activity from evoked potential fields on the scalp. (United States)

    Srebro, R; Oguz, R M; Hughlett, K; Sanders, N B; Purdy, P D


    A new method is described to calculate epicortical potential fields from scalp fields based on linear algebra. It requires detailed anatomical information, for each subject, obtained from MR images. The calculation is validated in a physical model of the human head and applied to human subjects. The results suggest that the method yields reliable epicortical fields that help to localize evoked cortical activity in humans.

  20. Vestibular-evoked myogenic potentials in miniature pigs

    Institute of Scientific and Technical Information of China (English)

    Xi Shi; Yan Zhang; Ya Li; Shiwei Qiu; Shili Zhang; Yaohan Li; Na Yuan; Yuehua Qiao; Shiming Yang


    Objective:To report detection of vestibular-evoked myogenic potentials (VEMPs) in the miniature pig. Methods:Potentials evoked by 1000 Hz tone bursts were recorded from neck extensor muscles and the masseter muscles in normal adult Bama miniature pigs anesthetized with 3%pentobarbital sodium and Carbachol II. Results:The latency of the first positive wave P from neck extensor muscles was 7.65 ± 0.64 ms, with an amplitude of 1.66 ± 0.34 uv and a rate of successful induction of 75%at 80 dB SPL. The latency of potentials evoked from the masseter muscles was 7.60 ± 0.78 ms, with an amplitude of 1.31 ± 0.28 uv and a rate successful induction of 66%at 80 dB SPL. 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.

  1. Evoked potentials and head injury. 2. Clinical applications. (United States)

    Rappaport, M; Hopkins, H K; Hall, K; Belleza, T


    The method of rating abnormality of evoked brain potential patterns and assessing the extent and severity of cortical and subcortical brain dysfunction in head injury patients described in Part I is applied in a clinical context. Evoked potential abnormality (EPA) scores are found to be significantly correlated both with admission and outcome disability approximately one year after head injury. Correlations increase with the increase in the number of sensory modalities tested. Correlations between EPA scores and clinical disability (measured by the Disability Rating Scale) decrease with time after injury. Significant correlations, however, persist for about 60 days after onset of injury. It was found that EP pattern abnormalities can reflect specific sensory (and at times motor) deficits in noncommunicative patients and thereby contribute significantly to early treatment and rehabilitation planning.

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

    DEFF Research Database (Denmark)

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


    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...

  3. [Long-latency auditory evoked potentials in cochlear implants]. (United States)

    Mata, J J; Jiménez, J M; Pérez, J; Postigo, A; Roldán, B


    Cortical evoked potentials were evaluated in patients with cochlear implants. In a group of 8 adults of different ages, the lingual state before implantation and during rehabilitation were evaluated. Using cortical evoked potentials, the results of the P300 wave in response to two tones, one frequent (1,000 Hz) and the other infrequent (2,000 Hz), presented at 70 and 80 dB HL were studied. Results were analyzed and compared in relation to locutive state, rehabilitation stage, and intensity of stimulus. Absolute latencies did not differ significantly. However, latency values in relation to reaction time were significantly longer in prelingual than in postlingual patients (p test). The results confirmed the normality of central cognitive processes in patients with cochlear implants in objective assessment of P300 latency. The results suggest differences between prelingual and postlingual patients in relation to central signal processing.

  4. Short latency vestibular evoked potentials in the chicken embryo (United States)

    Jones, S. M.; Jones, T. A.


    Electrophysiological responses to pulsed linear acceleration stimuli were recorded in chicken embryos incubated for 19 or 20 days (E19/E20). Responses occurred within the first 16 ms following the stimulus onset. The evoked potentials disappeared following bilateral labyrinthectomy, but persisted following cochlear destruction alone, thus demonstrating that the responses were vestibular. Approximately 8 to 10 response peaks could be identified. The first 4 positive and corresponding negative components (early peaks with latencies embryos was -15.9dBre 1.0 g/ms, which was significantly higher (P embryos and 2-week-old animals, but amplitude/intensity functions for embryos were significantly shallower than those for 2-week-old birds (P embryo and, as such, the method shows promise as an investigative tool. The results of the present study form the definitive basis for using vestibular evoked potentials in the detailed study of avian vestibular ontogeny and factors that may influence it.

  5. Visual evoked potentials in a patient with prosopagnosia. (United States)

    Small, M


    Visual evoked potentials (VEPs) were recorded from a 53-year-old man with prosopagnosia during presentation of slides of known and unknown faces and under two control conditions. ANOVA comparisons with a normal male group showed no differences in P100 amplitude, P300 amplitude or P300 latency. There were no significant evoked potential differences between the patient and controls specifically related to the face conditions. There was, however, a significant delay in the latency of P100 from both hemispheres during all types of stimuli. This prolonged latency was asymmetrical, showing a right sided emphasis with the control conditions: pattern reversal and slides of geometric designs. This finding, of a dissociation in the interhemispheric delay, provides physiological evidence of stimulus-specific organisation at an early, sensory level. The fact that the P100 component showed a marked delay, yet P300 fell within normal limits for amplitude and latency, suggests that this patient's problem lies at a perceptual level.

  6. [Visual evoked potentials (VEP) in anesthesia and intensive care]. (United States)

    Russ, W; Krumholz, W; Hempelmann, G


    Methodological considerations and different stimulation techniques of visual evoked potentials (VEP) are described. VEP can provide information about neurological function during anaesthesia, surgery and in the unconscious patient after head injury. The feasibility of the method for intraoperative monitoring in neuro- and cardiac surgery and the influence of general anaesthetics and other contributing factors such as temperature, paCO2, pO2, part are discussed.

  7. The Cervical Vestibular-Evoked Myogenic Potentials (cVEMPs) Recorded Along the Sternocleidomastoid Muscles During Head Rotation and Flexion in Normal Human Subjects. (United States)

    Ashford, Alexander; Huang, Jun; Zhang, Chunming; Wei, Wei; Mustain, William; Eby, Thomas; Zhu, Hong; Zhou, Wu


    Tone burst-evoked myogenic potentials recorded from tonically contracted sternocleidomastoid muscles (SCM) (cervical VEMP or cVEMP) are widely used to assess the vestibular function. Since the cVEMP response is mediated by the vestibulo-collic reflex (VCR) pathways, it is important to understand how the cVEMPs are determined by factors related to either the sensory components (vestibular end organs) or the motor components (SCM) of the VCR pathways. Compared to the numerous studies that have investigated effects of sound parameters on the cVEMPs, there are few studies that have examined effects of SCM-related factors on the cVEMPs. The goal of the present study is to fill this knowledge gap by testing three SCM-related hypotheses. The first hypothesis is that contrary to the current view, the cVEMP response is only present in the SCM ipsilateral to the stimulated ear. The second hypothesis is that the cVEMP response is not only dependent on tonic level of the SCM, but also on how the tonic level is achieved, i.e., by head rotation or head flexion. The third hypothesis is that the SCM is compartmented and the polarity of the cVEMP response is dependent on the recording site. Seven surface electrodes were positioned along the left SCMs in 12 healthy adult subjects, and tone bursts were delivered to the ipsilateral or contralateral ear (8 ms plateau, 1 ms rise/fall, 130 dB SPL, 50-4000 Hz) while subjects activated their SCMs by head rotation (HR condition) or chin downward head flexion (CD condition). The first hypothesis was confirmed by the finding that the contralateral cVEMPs were minimal at all recording sites for all the tested tones during both HR and CD conditions. The second hypothesis was confirmed by the finding that the ipsilateral cVEMPs were larger in HR condition than in CD condition at recording sites above and below the SCM midpoint. Finally, the third hypothesis was confirmed by the finding that the cVEMPs exhibit reversed polarities at the sites

  8. Perceptual learning of acoustic noise generates memory-evoked potentials. (United States)

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


    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.

  9. Cervical and ocular vestibular evoked myogenic potentials in Behcet's disease. (United States)

    Bayram, Ali; Doğan, Murat; Koç, Ali; Kalkan, Mehmet; Akçadağ, Alper; Özcan, İbrahim


    To investigate vestibular evoked myogenic potentials combined with audiologic status in Behcet's disease (BD) and to compare the results with normal healthy subjects. Cervical vestibular evoked myogenic potential (cVEMP) test, ocular vestibular evoked myogenic potential (oVEMP) test, Dix-Hallpike test, conventional pure tone audiometry (cPTA) and high frequency audiometry (HFA), and 226 and 1000Hz tympanometry were performed to each subject of the study. Cranial magnetic resonance imaging (MRI) with contrast enhancement was also performed to evaluate the central nervous system (CNS) in patients with BD. VEMP parameters including the mean peak latencies of p13-n23 and n10-p15, AR values and thresholds were not statistically different both in cVEMP and oVEMP between the BD and control groups. Except for 250Hz, mean audiological thresholds were significantly higher in the BD group. Five of the 20 patients had pathological cranial MRI findings that may be compatible with central nervous system involvement. To our knowledge, the present study is the first report investigating oVEMP and cVEMP responses combined with MRI findings in patients with BD. The presence of high frequency hearing loss is a common finding in BD and HFA may help early detection of hearing loss in patients with BD when combined with cPTA. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Brainstem auditory evoked potential abnormalities in type 2 diabetes mellitus

    Directory of Open Access Journals (Sweden)

    Sharat Gupta


    Full Text Available Background: Diabetes mellitus represents a syndrome complex in which multiple organ systems, including the central nervous system, are affected. Aim: The study was conducted to determine the changes in the brainstem auditory evoked potentials in type 2 diabetes mellitus. Materials and Methods: A cross sectional study was conducted on 126 diabetic males, aged 35-50 years, and 106 age-matched, healthy male volunteers. Brainstem auditory evoked potentials were recorded and the results were analyzed statistically using student′s unpaired t-test. The data consisted of wave latencies I, II, III, IV, V and interpeak latencies I-III, III-V and I-V, separately for both ears. Results: The latency of wave IV was significantly delayed only in the right ear, while the latency of waves III, V and interpeak latencies III-V, I-V showed a significant delay bilaterally in diabetic males. However, no significant difference was found between diabetic and control subjects as regards to the latency of wave IV unilaterally in the left ear and the latencies of waves I, II and interpeak latency I-III bilaterally. Conclusion: Diabetes patients have an early involvement of central auditory pathway, which can be detected with fair accuracy with auditory evoked potential studies.


    Institute of Scientific and Technical Information of China (English)

    陈薇; 陈慎仁; 陈璇; 吴静珊; 刘兴材


    The aim of this study is to explore the changes of visual evoked potentiaK VEP), brainstem auditory evoked potential (BAEP), Somatosensory e-voked potential (SEP), event-related potential(ERP) of patients with type 2 diabetes mellitus(DM).Methods VEP, BAEP, SEP, ERP were measured in 30 cases with type 2 DM (DM group) and in 30 age- and sex-matched healthy volunteers (Control group) by using Nicolet Viking Ⅳ EMG/EP instrument. The numerical values of VEP, BAEP, SEP and ERP were recorded and analyzed by SPSS.Results Abnormalities were found as follows: VEP in 20(66.7%), BAEP in 18(60%), MNSEP in 20(66.7%),PTNSEP in 22(73.3%), and ERP in 11 (36.67%) diabetic patients, including the disappearance of wave, prolonged wave latency and decreased wave amplitude. Compared with control group, the P100 latency of VEP, the latencies of wave Ⅰ and Ⅴ, amplitude of wave Ⅴ, the interpeak latencies (IPL) of each wave in BAEP, the latencies and wave amplitudes in N9 to P20 of MNSEP and in N9 to P38 of PTNSEP, as well a

  12. Effect of mechanical tactile noise on amplitude of visual evoked potentials: multisensory stochastic resonance. (United States)

    Méndez-Balbuena, Ignacio; Huidobro, Nayeli; Silva, Mayte; Flores, Amira; Trenado, Carlos; Quintanar, Luis; Arias-Carrión, Oscar; Kristeva, Rumyana; Manjarrez, Elias


    The present investigation documents the electrophysiological occurrence of multisensory stochastic resonance in the human visual pathway elicited by tactile noise. We define multisensory stochastic resonance of brain evoked potentials as the phenomenon in which an intermediate level of input noise of one sensory modality enhances the brain evoked response of another sensory modality. Here we examined this phenomenon in visual evoked potentials (VEPs) modulated by the addition of tactile noise. Specifically, we examined whether a particular level of mechanical Gaussian noise applied to the index finger can improve the amplitude of the VEP. We compared the amplitude of the positive P100 VEP component between zero noise (ZN), optimal noise (ON), and high mechanical noise (HN). The data disclosed an inverted U-like graph for all the subjects, thus demonstrating the occurrence of a multisensory stochastic resonance in the P100 VEP. Copyright © 2015 the American Physiological Society.

  13. Temporal resolution in the hearing system and auditory evoked potentials

    DEFF Research Database (Denmark)

    Miller, Lee; Beedholm, Kristian


    3pAB5. Temporal resolution in the hearing system and auditory evoked potentials. Kristian Beedholm Institute of Biology,University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark,, Lee A. Miller Institute of Biology,University of Southern Denmark, Campusvej 55, 5230...... of the MRTF is not straight forward, but is often used as a measure of the ability of the auditory system to encodetemporal changes. It is, however, shown here that the MRTF must depend on the waveform of the click-evoked AEP ceAEP, whichdoes not relate directly to temporal resolution. The theoretical...... of 0.5 ms Hann weighted130 kHz tone pips presented at an increasing rate chirped over a time span of 32 ms. The results reveal that the system's responsivenessdeclines roughly exponentially as a function of click rate with a rate constant of about -0.7 kHz and appears more rate limited thanimplied...

  14. Visual evoked potentials in children prenatally exposed to methylmercury

    DEFF Research Database (Denmark)

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


    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...... subjects after exclusion of subjects with abnormal vision conditions. We used multiple regression analysis to evaluate the association of mercury concentrations in cord blood and maternal hair at parturition with VEP latencies after adjustment for potential confounders that included the cord...

  15. Motor evoked potentials of the respiratory muscles in tetraplegic patients. (United States)

    Lissens, M A; Vanderstraeten, G G


    We studied the respiratory muscles with magnetic transcranial stimulation (TCS) in four spinal cord injured (SCI) patients as compared to age-matched controls from a database of 40 healthy subjects. These SCI patients all had spinal cord lesions above C6 level with a clinically incomplete tetraplegia. One patient was artificially ventilated. Motor evoked potentials (MEPs) were recorded from the diaphragm, the scalenes, the parasternal intercostals and the expiratory rectus abdominis during inspiration and expiration. In patients with incomplete tetraplegia MEP latency times were significantly prolonged in the scalenes and the parasternal intercostals, both during inspiration and expiration, and were nearly normal for the diaphragm, which was found to be more or less preserved. The mean MEP amplitudes in these patients for all inspiratory muscles studied were significantly decreased in tetraplegic patients, in part due to a decreased number of innervating axons and muscle hypotrophy. No MEPs could be obtained from the abdominal muscles, except in one C3 tetraplegic patient, in whom only a very small response was seen during expiration, with a very delayed latency time. The much lower location of their innervating nerve roots (T10) and the much longer distance of their spinal exit zone from the level of injury at the cervical spinal cord might at least partially explain this phenomenon. In the ventilator-dependent tetraplegic patient no MEPs could be obtained from any of the muscles studied. Thus, magnetic TCS is a painless and easily applicable technique to investigate the central motor conduction properties of the respiratory muscles, both in healthy humans and in tetraplegic patients.

  16. Brainstem auditory evoked potentials in children with lead exposure

    Directory of Open Access Journals (Sweden)

    Katia de Freitas Alvarenga


    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.

  17. Baroreceptor activation attenuates attentional effects on pain-evoked potentials. (United States)

    Gray, Marcus A; Minati, Ludovico; Paoletti, Giulia; Critchley, Hugo D


    Focused attention typically enhances neural nociceptive responses, reflected electroencephalographically as increased amplitude of pain-evoked event-related potentials (ERPs). Additionally, pain-evoked ERPs are attenuated by hypertension and baroreceptor activity, through as yet unclear mechanisms. There is indirect evidence that these two effects may interact, suggesting that baroreceptor-related modulation of nociception is more than a low-level gating phenomenon. To address this hypothesis, we explored in a group of healthy participants the combined effects of cue-induced expectancy and baroreceptor activity on the amplitude of pain-evoked ERPs. Brief nociceptive skin stimuli were delivered during a simple visual task; half were preceded by a visual forewarning cue, and half were unpredictable. Nociceptive stimuli were timed to coincide either with systole (maximum activation of cardiac baroreceptors) or with diastole (minimum baroreceptor activation). We observed a strong interaction between expectancy and cardiac timing for the amplitude of the P2 ERP component; no effects were observed for the N2 component. Cued stimuli were associated with larger P2 amplitude, but this effect was abolished for stimuli presented during baroreceptor activation. No cardiac timing effect was observed for un-cued stimuli. Taken together, these findings suggest a close integration of cognitive-affective aspects of expectancy and baroreceptor influences on pain, and as such may cast further light on mechanisms underlying mental and physiological contributions to clinical pain.

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

    Directory of Open Access Journals (Sweden)

    Domenica eVeniero


    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.

  19. Intraoperative Monitoring: Recent Advances in Motor Evoked Potentials. (United States)

    Koht, Antoun; Sloan, Tod B


    Advances in electrophysiological monitoring have improved the ability of surgeons to make decisions and minimize the risks of complications during surgery and interventional procedures when the central nervous system (CNS) is at risk. Individual techniques have become important for identifying or mapping the location and pathway of critical neural structures. These techniques are also used to monitor the progress of procedures to augment surgical and physiologic management so as to reduce the risk of CNS injury. Advances in motor evoked potentials have facilitated mapping and monitoring of the motor tracts in newer, more complex procedures.

  20. Ocular vestibular evoked myogenic potentials in normal-hearing adults


    Mohammad Kamali; Homa Zarinkoub; Akram Pourbakht; Abdoreza Sheibanizade; Maryam Ramezani; Seyede Nazanin Hajari


    Background and Aim: Ocular vestibular-evoked myogenic potential (oVEMP) is a novel vestibular function test. This short-latency response can be recorded through contracting extraocular muscles by high-intensity acoustic stimulation and can be used to evaluate contralateral ocular-vestibular reflex. The aim of this study was to record and compare the amplitude, latency, asymmetry ratio and occurrence percentage of oVEMP (n10) and cervical VEMP (p13) responses in a group of normal adult subject...

  1. Clinical application of vestibular evoked myogenic potential (VEMP). (United States)

    Murofushi, Toshihisa


    The author reviewed clinical aspects of vestibular evoked myogenic potentials (VEMPs). Now two types of VEMPs are available. The first one is cervical VEMP, which is recorded in the sternocleidomastoid muscle and predominantly reflects sacculo-collic reflex. The other is ocular VEMP, which is usually recorded below the lower eye lid and predominantly reflects utriculo-ocular reflex. VEMPs play important roles not only for assessment of common vestibular diseases but also for establishment of new clinical entities. Clinical application in Meniere's disease, vestibular neuritis, benign paroxysmal positional vertigo, vestibular migraine, idiopathic otolithic vertigo, and central vertigo/dizziness was reviewed. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  2. Conditioning effect of transcranial magnetic stimulation evoking motor-evoked potential on V-wave response. (United States)

    Grosprêtre, Sidney; Martin, Alain


    The aim of this study was to examine the collision responsible for the volitional V-wave evoked by supramaximal electrical stimulation of the motor nerve during voluntary contraction. V-wave was conditioned by transcranial magnetic stimulation (TMS) over the motor cortex at several inter-stimuli intervals (ISI) during weak voluntary plantar flexions (n = 10) and at rest for flexor carpi radialis muscle (FCR; n = 6). Conditioning stimulations were induced by TMS with intensity eliciting maximal motor-evoked potential (MEPmax). ISIs used were ranging from -20 to +20 msec depending on muscles tested. The results showed that, for triceps surae muscles, conditioning TMS increased the V-wave amplitude (~ +250%) and the associated mechanical response (~ +30%) during weak voluntary plantar flexion (10% of the maximal voluntary contraction -MVC) for ISIs ranging from +6 to +18 msec. Similar effect was observed at rest for the FCR with ISI ranging from +6 to +12 msec. When the level of force was increased from 10 to 50% MVC or the conditioning TMS intensity was reduced to elicit responses of 50% of MEPmax, a significant decrease in the conditioned V-wave amplitude was observed for the triceps surae muscles, linearly correlated to the changes in MEP amplitude. The slope of this correlation, as well as the electro-mechanical efficiency, was closed to the identity line, indicating that V-wave impact at muscle level seems to be similar to the impact of cortical stimulation. All these results suggest that change in V-wave amplitude is a great index to reflect changes in cortical neural drive addressed to spinal motoneurons.

  3. Prognosis in prolonged coma patients with diffuse axonal injury assessed by somatosensory evoked potential

    Institute of Scientific and Technical Information of China (English)

    Xiujue Zheng; Mantao Chen; Jingqi Li; Fei Cao


    A total of 43 prolonged coma patients with diffuse axonal injury received the somatosensory evoked potential examination one month after injury in the First Affiliated Hospital, School of Medicine, Zhejiang University in China. Somatosensory evoked potentials were graded as normal, abnormal or absent (grades I–III) according to N20 amplitude and central conduction time. The outcome in patients with grade III somatosensory evoked potential was in each case unfavorable. The prognostic accuracy of grade III somatosensory evoked potential for unfavorable and non-awakening outcome was 100% and 80%, respectively. The prognostic accuracy of grade I somatosensory evoked potential for favorable and wakening outcome was 86% and 100%, respectively. These results suggest that somatosensory evoked potential grade is closely correlated with coma severity and degree of recovery. Somatosensory evoked potential is a valuable diagnostic tool to assess prognosis in prolonged coma patients with diffuse axonal injury.

  4. Evoked brain potentials and disability in brain-damaged patients. (United States)

    Rappaport, M; Hall, K; Hopkins, K; Belleza, T; Berrol, S; Reynolds, G


    Various measures of evoked brain potential abnormality (EPA) were correlated with disability ratings (DR) for 35 brain-damaged patients. EPA data consisted of judgements of abnormality of ipsilateral, contralateral and bilateral responses to auditory and visual stimuli reflecting activity in the brain stem, subcortex and cortex. DR data were obtained from a scale developed for this study to quantize and categorize patients with a wide range of disabilities from coma to normal functioning. EPA scores based on visual and auditory cortical responses showed significantly positive correlations with degree of disability. Visual response correlation was .49, auditory .38 and combined visual and auditory .51. It was concluded that EPA measures can reflect disability independently of clinical information. They are useful in assessing brain function in general and, specifically, in assessing impairment of sensory function. The evoked potential technique was particularly useful in patients who were not able to participate fully in their own examination. There were indications that the technique may also be valuable in monitoring progress and in predicting clinical outcome in brain-damaged patients.

  5. Visual evoked potentials, reaction times and eye dominance in cricketers. (United States)

    Thomas, N G; Harden, L M; Rogers, G G


    Few studies have examined the physiology of cricket, including the difference in ability between batsmen to make controlled contact with a ball bowled at high speed. We therefore measured visual evoked potentials and choice reaction times with dominant eyes, non-dominant eyes, and both eyes together, in 15 elite batsmen and 10 elite bowlers (aged 20.9 SD 1.9 years) and 9 control subjects (aged 20.2 SD 1.5 years). The latency and amplitude of waves N70, P100 and N145 were determined for each visual evoked potential (VEP). In addition interpeak latencies and peak to peak amplitudes were measured. The subjects also completed a choice reaction test to a visual stimulus. We found that cricketers were not more likely to have crossed dominance (dominant eye contralateral to dominant hand) than controls. Cricketers had a faster latency for VEP wave N70 than controls (p=0.03). However reaction time was not different between cricketers and the control group. Across all subjects, in comparison to monocular testing, binocular testing led to a faster choice reaction time (p=0.02) and larger amplitudes of VEP wave N70 (p=0.01). Visual processing during the first 100(-1)50 ms of the balls flight together with binocular vision facilitates retinal activation in talented cricketers.

  6. Cognitive evoked potentials P300 after radiation exposure. (United States)

    Loganovsky, K M; Kuts, K V


    The study was aimed at evaluating features of brain information processes and cognitive functioning in the remote period after irradiation due to the Chornobyl accident by using cognitive evoked potentials P300. The study included 128 people, 112 male Chornobyl clean up workers in 1986-1987 with the records of radiation doses available in Clinical and Epidemiological Registry (CER) of State Institution «National Research Center for Radiation Medicine of the National Academy of Medical Sciences of Ukraine» (NRCRM) (study group) and 16 unexposed persons due to the Chornobyl disaster (control group). At the time of the survey the average age of clean up workers (M ± SD) was (57.3 ± 5.9) years, range 44-65 years, and of unex posed persons was (57.3 ± 6.5) years, range 44-65 years. Radiation doses were within the range 0.0002-1.23 Gy, with the arithmetic mean dose (M ± SD) of (0.2 ± 0.2) Gy and the geometric mean dose of 0.1 Gy. The radiocerebral effect in the projection of the left posterior superior temporal gyrus (Wernicke's area) proportionally to the radiation dose with the possible threshold of 0.05 Gy of total irradiation was revealed, with increasing radiation dose cognitive component P300 amplitude reduces and its latency period (LP) increases, espe cially at doses > 0.3-0.5 Gy. At doses > 0.5 Gy the functional relationship with the radiation dose for LP P300 increase in the projection of Wernicke's area (r = 0.9; p = 0.027) has been found. The neurophysiological features detected are fully consistent with hypotheses both on radiosensitiv ity of human central nervous system and accelerated aging of the brain under the influence of small doses of ioniz ing radiation, and have questioned the feasibility of long term manned space flights (including Mars) until the development of adequate radiation hygiene standardization for space crews and invention of means for radiation protection of space flights. Further dynamic clinical and neurophysiological

  7. Band limited chirp stimulation in vestibular evoked myogenic potentials. (United States)

    Walther, Leif Erik; Cebulla, Mario


    Air conducted vestibular evoked myogenic potentials (VEMP) can be elicited by various low frequency and intense sound stimuli, mainly clicks or short tone bursts (STB). Chirp stimuli are increasingly used in diagnostic audiological evaluations as an effective means to obtain acoustically evoked responses in narrowed or extended frequency ranges. We hypothesized in this study that band limited chirp stimulation, which covers the main sensitivity range of sound sensitive otolithic afferents (around 500 Hz), might be useful for application in cervical and ocular VEMP to air conduction. For this purpose we designed a chirp stimulus ranging 250-1000 Hz (up chirp). The chirp stimulus was delivered with a stimulus intensity of 100 dB nHL in normal subjects (n = 10) and patients with otolith involvement (vestibular neuritis) (n = 6). Amplitudes of the designed chirp ("CW-VEMP-chirp, 250-1000 Hz") were compared with amplitudes of VEMPs evoked by click stimuli (0.1 ms) and a short tone burst (STB, 1-2-1, 8 ms, 500 Hz). CVEMPs and oVEMPs were detectable in 9 of 10 normal individuals. Statistical evaluation in healthy patients revealed significantly larger cVEMP and oVEMP amplitudes for CW-VEMP-chirp (250-1000 Hz) stimuli. CVEMP amplitudes evoked by CW-VEMP-chirp (250-1000 Hz) showed a high stability in comparison with click and STB stimulation. CW-VEMP-chirp (250-1000 Hz) showed abnormal cVEMP and oVEMP amplitudes in patients with vestibular neuritis, with the same properties as click and STB stimulated VEMPs. We conclude that the designed CW-VEMP-chirp (250-1000 Hz) is an effective stimulus which can be further used in VEMP diagnostic. Since a chirp stimulus can be easily varied in its properties, in particular with regard to frequency, this might be a promising tool for further investigations.

  8. Automatic denoising of single-trial evoked potentials. (United States)

    Ahmadi, Maryam; Quian Quiroga, Rodrigo


    We present an automatic denoising method based on the wavelet transform to obtain single trial evoked potentials. The method is based on the inter- and intra-scale variability of the wavelet coefficients and their deviations from baseline values. The performance of the method is tested with simulated event related potentials (ERPs) and with real visual and auditory ERPs. For the simulated data the presented method gives a significant improvement in the observation of single trial ERPs as well as in the estimation of their amplitudes and latencies, in comparison with a standard denoising technique (Donoho's thresholding) and in comparison with the noisy single trials. For the real data, the proposed method largely filters the spontaneous EEG activity, thus helping the identification of single trial visual and auditory ERPs. The proposed method provides a simple, automatic and fast tool that allows the study of single trial responses and their correlations with behavior.


    Directory of Open Access Journals (Sweden)



    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

  10. Assessment of visual disability using visual evoked potentials

    Directory of Open Access Journals (Sweden)

    Jeon Jihoon


    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

  11. Laser-evoked potentials in primary headaches and cranial neuralgias. (United States)

    de Tommaso, Marina


    Using neurophysiological methods to explore nociceptive pathways may improve knowledge of the functional changes subtending pain processing in the different forms of headache and facial pain. Laser-evoked potentials (LEPs) are a reliable neurophysiological assay for the clinical assessment of pain syndromes. Reduced amplitude of LEPs seems to characterize trigeminal neuralgia and painful temporomandibular disorders, suggesting the neuropathic origin of pain. In tension-type headache, as well as in fibromyalgia, enhanced pericranial LEP amplitude suggests the psychogenic origin of pain. In migraine, a normal amplitude of basal LEPs with reduced habituation and altered attentive modulation seems to express a general dysfunction of cortical pain processing, which may also contribute, other than to predispose, to the persistence of migraine. LEPs may be employed in the clinical evaluation of the neurophysiological and psychophysiological aspects of pain in the different forms of headaches and facial pain to improve the therapeutic approach and provide an objective measure of treatment efficacy.

  12. Visual evoked potentials and selective attention to points in space (United States)

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


    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.

  13. Evoked potentials in Guillain-Barré syndrome. (United States)

    Ropper, A H; Chiappa, K H


    We studied evoked potentials (EPs) in 27 patients with typical acute Guillain-Barré syndrome and 3 with Fisher's syndrome. Three of 21 had BAEP abnormalities: 1 with bilateral I-III, 1 with unilateral I-III, and another with unilateral III-V interwave latency prolongations. Three with Fisher's syndrome had normal BAEPs (one had a poorly formed wave V unilaterally with one click polarity only). Ten of 21 median nerve EPs and 9 of 12 peroneal or tibial nerve somatosensory EPs were abnormal. Seven patients with normal somatosensory EPs had abnormal F waves from the same nerve; none had normal late responses and abnormal somatosensory EPs. These observations differ from previous reports on the frequency and interpretation of EP abnormalities in Guillain-Barré syndrome.

  14. Multi-Channel Noise Reduced Visual Evoked Potential Analysis (United States)

    Palaniappan, Ramaswamy; Raveendran, Paramesran; Nishida, Shogo

    In this paper, Principal Component Analysis (PCA) is used to reduce noise from multi-channel Visual Evoked Potential (VEP) signals. PCA is applied to reduce noise from multi-channel VEP signals because VEP signals are more correlated from one channel to another as compared to noise during visual perception. Emulated VEP signals contaminated with noise are used to show the noise reduction ability of PCA. These noise reduced VEP signals are analysed in the gamma spectral band to classify alcoholics and non-alcoholics with a Fuzzy ARTMAP (FA) neural network. A zero phase Butterworth digital filter is used to extract gamma band power in spectral range of 30 to 50 Hz from these noise reduced VEP signals. The results using 800 VEP signals give an average FA classification of 92.50 % with the application of PCA and 83.33 % without the application of PCA.

  15. Spatial coincidence modulates interaction between visual and somatosensory evoked potentials. (United States)

    Schürmann, Martin; Kolev, Vasil; Menzel, Kristina; Yordanova, Juliana


    The time course of interaction between concurrently applied visual and somatosensory stimulation with respect to evoked potentials (EPs) was studied. Visual stimuli, either in the left or right hemifield, and electric stimuli to the left wrist were delivered either alone or simultaneously. Visual and somatosensory EPs were summed and compared to bimodal EPs (BiEP, response to actual combination of both modalities). Temporal coincidence of stimuli lead to sub-additive or over-additive amplitudes in BiEPs in several time windows between 75 and 275 ms. Additional effects of spatial coincidence (left wrist with left hemifield) were found between 75 and 300 ms and beyond 450 ms. These interaction effects hint at a temporo-spatial pattern of multiple brain areas participating in the process of multimodal integration.

  16. Visual evoked potentials in neuromyelitis optica and its spectrum disorders. (United States)

    Ringelstein, Marius; Kleiter, Ingo; Ayzenberg, Ilya; Borisow, Nadja; Paul, Friedemann; Ruprecht, Klemens; Kraemer, Markus; Cohn, Eva; Wildemann, Brigitte; Jarius, Sven; Hartung, Hans-Peter; Aktas, Orhan; Albrecht, Philipp


    Optic neuritis (ON) is a key feature of neuromyelitis optica (NMO). Recently, NMO patients of predominantly Afro-Brazilian origin were evaluated by visual evoked potentials (VEPs) and showed marked amplitude reductions. Here, we analyzed VEPs in a predominantly Caucasian cohort, consisting of 43 patients with definite NMO, 18 with anti-aquaporin (AQP) 4 antibody-seropositive NMO spectrum disorders and 61 matched healthy controls. We found reduced amplitudes in only 12.3%, prolonged latencies in 41.9% and a lack of response in 14.0% of NMO eyes. Delayed P100 latencies in eyes without prior ON suggested this was a subclinical affection. The data indicate heterogenous patterns in NMO, warranting further investigation.

  17. Somatosensory evoked potentials predict neurolysis outcome in meralgia paraesthetica. (United States)

    Siu, Timothy L T; Chandran, K Nadana


    The role of somatosensory evoked potentials (SEP) in predicting the outcome of nerve entrapment syndrome following surgical release has not been fully verified. All patients included in our study had preoperative SEP recordings and had undergone neurolysis for treatment of meralgia paraesthetica by our senior author (KNC) between 1996 and 2000. The outcome of surgery was assessed 6 weeks after the procedure; follow up was continued at 3 month intervals if symptoms persisted. Telephone interviews were conducted to assess long-term results. Univariate and multivariate logistic regression analyses were used to establish the predictive value of side-to-side N1 and P1 latency differences in obtaining complete relief of symptoms following surgery. Twenty-four patients who had preoperative SEP recordings and had undergone neurolysis for meralgia paraesthetica were followed for 4.0 +/- 1.5 (SD) years. A prolonged side-to-side N1 latency difference (DeltaN1) was found to be significantly associated with complete relief of symptoms at about 6 weeks postoperatively, after adjustment for age, sex and duration of symptoms (OR, 1.75; CI, 1.03-2.96). Logistic regression identified a critical cut-off value of 8 ms (OR, 27.2; CI, 1.4-547.0). This association disappeared with longer follow up. Somatosensory evoked potentials provide significant data for prediction of good surgical outcome for meralgia paraesthetica. Re-evaluation of the diagnosis, adequate trial of conservative treatments and special attention to anomalous branches are recommended for patients with low preoperative DeltaN1 values.

  18. Brainstem auditory-evoked potentials in two meditative mental states

    Directory of Open Access Journals (Sweden)

    Kumar Sanjay


    Full Text Available Context: Practicing mental repetition of "OM" has been shown to cause significant changes in the middle latency auditory-evoked potentials, which suggests that it facilitates the neural activity at the mesencephalic or diencephalic levels. Aims: The aim of the study was to study the brainstem auditory-evoked potentials (BAEP in two meditation states based on consciousness, viz. dharana, and dhyana. Materials and Methods: Thirty subjects were selected, with ages ranging from 20 to 55 years (M=29.1; ±SD=6.5 years who had a minimum of 6 months experience in meditating "OM". Each subject was assessed in four sessions, i.e. two meditation and two control sessions. The two control sessions were: (i ekagrata, i.e. single-topic lecture on meditation and (ii cancalata, i.e. non-targeted thinking. The two meditation sessions were: (i dharana, i.e. focusing on the symbol "OM" and (ii dhyana, i.e. effortless single-thought state "OM". All four sessions were recorded on four different days and consisted of three states, i.e. pre, during and post. Results: The present results showed that the wave V peak latency significantly increased in cancalata, ekagrata and dharana, but no change occurred during the dhyana session. Conclusions: These results suggested that information transmission along the auditory pathway is delayed during cancalata, ekagrata and dharana, but there is no change during dhyana. It may be said that auditory information transmission was delayed at the inferior collicular level as the wave V corresponds to the tectum.

  19. The diagnostic significance of the multifocal pattern visual evoked potential in glaucoma. (United States)

    Graham, S L; Klistorner, A


    The concept of objective perimetry is an exciting one because it strives to assess glaucoma damage without relying on psychophysical testing. The recent introduction of multifocal stimulus recording has enhanced our ability to examine the human visual field using electrophysiology. A multifocal pattern visual evoked potential can now be recorded, testing up to 60 sites within the central 25 degrees. The test requires only that the subject fixate on a target, while a cortically scaled dartboard pattern stimulus undergoes pseudorandom alternation within each of the test segments. In its present configuration the test requires at least 8 minutes recording time per eye. Modified bipolar electrode positions are required to ensure that adequate signals are detected from all parts of the visual field. In glaucoma patients, pattern visual evoked potential amplitudes have been shown to reflect visual field loss with reduction of signal amplitude in the affected areas. This technique represents the first major step toward objective detection of visual field defects in glaucoma.


    Institute of Scientific and Technical Information of China (English)

    LU Yingzhi; ZONG Wenbin; CHEN Xingshi


    Objective: In order to investigate the brain function of patients with Qigong induced mental disorder (QIMD), this study was carried out. Methods: Four kinds of evoked potentials, including contingent negative variation (CNV), auditory evoked potentials (AEP), visual evoked potentials (VEP), and somatosensory evoked potentials (SEP), were recorded from 12 patients with Qigong induced mental disorder.Comparison of their evoked potentials with the data from some normal controls was made. Results: The results revealed that there were 3 kinds of abnormal changes in evoked potentials of patients with QIMD that is latency prolongation, amplitude increase and amplitude decrease, as compared with normal controls. Conclusion: Brain dysfunction of patients with QIMD was confirmed. Its biological mechanism needs further studying.

  1. A simple model for the generation of the vestibular evoked myogenic potential (VEMP)

    NARCIS (Netherlands)

    Wit, HP; Kingma, CM


    Objective: To describe the mechanism by which the vestibular evoked myogenic potential is generated. Methods: Vestibular evoked myogenic potential generation is modeled by adding a large number of muscle motor unit action potentials. These action potentials occur randomly in time along a 100 ms long

  2. Visual Evoked Potentials in Patients with Classic Migraine

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    Akbar Hamzei-Moghaddam


    Full Text Available Background: Migraine is considered as a chronic disease. Ocular symptoms and sensitivity to light stimuli are common in the patients with such disease. There are some evident that visual system function in the patients with migraine is impaired even between the attacks as compared with health people. In this study, we examine Visual Evoked Potential in 30 patients suffered from migraine before, during and after aura. Materials and Methods: 30 patients suffered from classic migraine and with visual aura were evaluated in terms of visual stimulatory potentials before, during and after aura. P-100 latency and amplitude were evaluation criteria in our study. The results of this investigation were evaluated by χ2 test.Results: Abnormal amplitude frequency was occurred in 17 cases before aura, in 27 cases during aura and in 20 cases, it occurred after aura. Reduction of the amplitude wave p-100 during and after aura was significantly more in both eyes (p<0.05. Ten cases had abnormal P-100 latency during aura and the other two cases had it after aura. There is a significant difference in the P-100 latency during aura (p<0.05. There is no difference between the changes in visual stimulatory potentials with gender.Conclusion: Some changes were found in the parameters in the visual stimulatory potentials in the patients with classic migraine before, during and after aura.

  3. Recording visual evoked potentials and auditory evoked P300 at 9.4T static magnetic field. (United States)

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


    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.

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

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    Jorge Arrubla

    Full Text Available 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.

  5. Cervical and ocular vestibular evoked myogenic potentials in multiple sclerosis participants


    Parsa, Maryam Sadat; Mohammadkhani, Ghassem; Hajabolhassani, Fahimeh; Jalaee, Shohreh; Zakeri, Hassanali


    Background: Multiple sclerosis (MS) is a chronic neurological disease that affects brain and spinal cord. The infratentorial region contains the cerebellum and brainstem. Vestibular evoked myogenic potentials (VEMPs) are short-latency myogenic responses. Cervical vestibular evoked myogenic potential (cVEMP) is a manifestation of vestibulocolic reflex and ocular vestibular evoked myogenic potential (oVEMP) contributes to the linear vestibular?ocular reflex. The aim of this study was to evaluat...

  6. Promontory electrical stimulation to elicit vestibular evoked myogenic potentials (VEMPs). (United States)

    Park, Jonas J-H; Shen, Anmin; Westhofen, Martin


    Vestibular evoked myogenic potentials (VEMPs) provoked electrically at the promontory provide a feasible method to record vestibular responses in awake patients. Electrically evoked VEMP testing has been performed by galvanic stimulation at the mastoid so far. The present study examined an electrical stimulation mode close to the otolith organs at the promontory. Fourteen cochlear implant candidates who were planned for clinical routine promontory stimulation testing (PST) to assess auditory nerve function underwent promontory VEMP testing. After testing the cochlear nerve function during PST promontory cervical VEMPs (p-c-VEMPs) and promontory ocular VEMPs (p-o-VEMPs) were recorded during subsequent transtympanic electrical stimulation at the promontory. Promontory VEMP testing was well tolerated by the patients. Mean latencies for p-c-VEMPs were 10.30 ± 2.23 ms (p1) and 17.86 ± 3.83 ms (n1). Mean latencies for p-o-VEMPs were 7.64 ± 1.24 ms (n1) and 11.2 ± 1.81 ms (p1). The stimulation threshold level was measured at 0.15 ± 0.07 mA for p-c-VEMPs and at 0.19 ± 0.11 mA for p-o-VEMPs. The discomfort level was found to be at 0.78 ± 0.29 mA for p-c-VEMPs and at 0.69 ± 0.25 mA for p-oVEMPs. Mean p1-n1 amplitude in p-c-VEMPs was 124.78 ± 56.55 µV and p-o-VEMPs showed a mean n1-p1 amplitude of 30.94 ± 18.98 µV.

  7. Exploring the Mechanisms of Exercise-Induced Hypoalgesia Using Somatosensory and Laser Evoked Potentials. (United States)

    Jones, Matthew D; Taylor, Janet L; Booth, John; Barry, Benjamin K


    Exercise-induced hypoalgesia is well described, but the underlying mechanisms are unclear. The aim of this study was to examine the effect of exercise on somatosensory evoked potentials, laser evoked potentials, pressure pain thresholds and heat pain thresholds. These were recorded before and after 3-min of isometric elbow flexion exercise at 40% of the participant's maximal voluntary force, or an equivalent period of rest. Exercise-induced hypoalgesia was confirmed in two experiments (Experiment 1-SEPs; Experiment 2-LEPs) by increased pressure pain thresholds at biceps brachii (24.3 and 20.6% increase in Experiment 1 and 2, respectively; both d > 0.84 and p 0.57 and p evoked potentials (14.6% decrease, d = -0.42, p = 0.004) and somatosensory evoked potentials (10.9% increase, d = -0.02, p = 1) were also observed, while an equivalent period of rest showed similar habituation (laser evoked potential: 7.3% decrease, d = -0.25, p = 0.14; somatosensory evoked potential: 20.7% decrease, d = -0.32, p = 0.006). The differential response of pressure pain thresholds and heat pain thresholds to exercise is consistent with relative insensitivity of thermal nociception to the acute hypoalgesic effects of exercise. Conflicting effects of exercise on somatosensory evoked potentials and laser evoked potentials were observed. This may reflect non-nociceptive contributions to the somatosensory evoked potential, but could also indicate that peripheral nociceptors contribute to exercise-induced hypoalgesia.

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

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    Bahar Özbek


    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.

  9. Long Latency Auditory Evoked Potential in Term and Premature Infants

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    Didoné, Dayane Domeneghini


    Full Text Available Introduction The research in long latency auditory evokes potentials (LLAEP in newborns is recent because of the cortical structure maturation, but studies note that these potentials may be evidenced at this age and could be considered as indicators of cognitive development. Purpose To research the exogenous potentials in term and premature infants during their first month of life. Materials and Methods The sample consisted of 25 newborns, 15 term and 10 premature infants. The infants with gestational age under 37 weeks were considered premature. To evaluate the cortical potentials, the infants remained in natural sleep. The LLAEPs were researched binaurally, through insertion earphones, with frequent /ba/ and rare /ga/ speech stimuli in the intensity of 80 dB HL (decibel hearing level. The frequent stimuli presented a total of 80% of the presentations, and the rare, 20%. The data were statistically analyzed. Results The average gestational age of the term infants was 38.9 weeks (± 1.3 and for the premature group, 33.9 weeks (± 1.6. It was possible to observe only the potentials P1 and N1 in both groups, but there was no statistically significant difference for the latencies of the components P1 and N1 (p > 0.05 between the groups. Conclusion It was possible to observe the exogenous components P1 and N1 of the cortical potentials in both term and preterm newborns of no more than 1 month of age. However, there was no difference between the groups.

  10. Vestibular evoked myogenic potentials in patients with ankylosing spondylitis. (United States)

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


    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.

  11. Vestibular evoked myogenic potentials (VEMPs) in central neurological disorders. (United States)

    Venhovens, J; Meulstee, J; Verhagen, W I M


    Several types of acoustic stimulation (i.e. tone bursts or clicks), bone-conducted vibration, forehead taps, and galvanic stimulation elicit myogenic potentials. These can be recorded in cervical and ocular muscles, the so called vestibular evoked myogenic potentials (VEMPs). The cervical VEMP (cVEMP) resembles the vestibulo-collic reflex and the responses can be recorded from the ipsilateral sternocleidomastoid muscle. The ocular VEMP resembles the vestibulo-ocular reflex and can be recorded from extra-ocular muscles by a surface electrode beneath the contralateral infraorbital margin. Initially, the literature concerning VEMPs was limited to peripheral vestibular disorders, however, the field of VEMP testing is rapidly expanding, with an increasing focus on central neurological disorders. The current literature concerning VEMP abnormalities in central neurological disorders is critically reviewed, especially regarding the methodological aspects in relation to quality as well as the clinical interpretation of the VEMP results. Suggestions for further research are proposed as well as some clinically useful indications. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  12. Vestibular evoked myogenic potential findings in multiple sclerosis. (United States)

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


    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.

  13. [Exploration of the optic and somatosensory pathways with cerebral evoked potentials]. (United States)

    Ghezzi, A; Zibetti, A


    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.

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

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    Ruchi Kothari


    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

  15. Analysis of brain-stem auditory evoked potential and visual evoked potential in patients with Parkinson disease

    Institute of Scientific and Technical Information of China (English)

    Qiaorong Deng; Jianzhong Deng; Yanmin Zhao; Xiaohai Yan; Pin Chen


    BACKGROUND: With the development of neuroelectrophysiology, it had been identified that all kinds of evoked potentials might reflect the functional status of corresponding pathway. Evoked potentials recruited in the re search of PD, it can be known whether other functional pathway of nervous system is impaired. OBJECTIVE: To observe whether brainstem auditory and visual passageway are impaired in patients with Parkinson disease (PD), and compare with non-PD patients concurrently. DESIGN: A non-randomized concurrent controlled observation. SETTINGS: Henan Provincial Tumor Hospital; Anyang District Hospital. PARTICIPANTS: Thirty-two cases of PD outpatients and inpatients, who registered in the Department of Neurology, Anyang District Hospital from October 1997 to February 2006, were enrolled as the PD group, including 20 males and 12 females, aged 50-72 years old. Inclusive criteria: In accordance with the diagnostic criteria of PD recommended by the dyskinesia and PD group of neurology branch of Chinese Medical Association. Patients with diseases that could cause Parkinson syndrome were excluded by CT scanning or MRI examination. Meanwhile, 30 cases with non-neurological disease were selected from the Department of Internal Medicine of our hospital as the control group, including 19 males and 11 females, aged 45-70 years old. Including criteria: Without history of neurological disease or psychiatric disease; showing normal image on CT. And PD, Parkinson syndrome and Parkinsonism-plus were excluded by professional neurologist. All the patients were informed and agreed with the examination and clinical observation. METHODS: The electrophysiological examination and clinical observation of the PD patients and controls were conducted. The Reporter type 4-channel evoked potential machine (Italy) was used to check brain-stem auditory evoked potential (BAEP) and visual evoked potential (VEP). Why to be examined was explained to test taker. BAEP recording electrode was plac

  16. A Subspace Method for Dynamical Estimation of Evoked Potentials

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    Stefanos D. Georgiadis


    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. Vestibular evoked myogenic potential in sudden sensorineural hearing loss

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    Feroze Kancharu Khan


    Full Text Available Aim and Objective: To investigate saccular damage in patients with sudden sensorineural hearing loss (SSNHL with or without vertigo and to evaluate the saccular damage according to the hearing loss and presence or absence of vertigo. Materials and Methods: All tests done in this study were performed in the audio vestibular unit of ENT department from September 2009 to November 2010. Statistical Analysis Used: The association between the severity of hearing loss and changes in the vestibular evoked myogenic potential (VEMP recordings were assessed using descriptive statistics. The pattern of VEMP in different diseases and also the behavior of VEMP in presence or absence of vertigo were evaluated using SPSS 15. Results: Among 27 patients there were 11 cases of idiopathic SSNHL. Out of nine unaffected ears, 88% had normal and 12% had absent VEMP. Whereas out of 13 affected ears, only 53.9% had normal VEMP. Among all the 54 ears, 17 ears had normal hearing. In this group 76.47% had normal VEMP. The group with hearing loss > 90 dB had 61.53% absent VEMP. Conclusions: In patients with unilateral SSNHL, there was a tendency for the affected ear to have absent VEMP indicating the saccular involvement. The extent of saccular damage did not correspond to the amount of hearing loss or presence or absence of vertigo.

  18. Pattern reversal visual evoked potentials in migraine subjects without aura

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    Pedro F. Moreira Filho


    Full Text Available Twenty seven patients with migraine without aura were investigated. The age was between 12 and 54 years; 5 were men and 22 women. The diagnosis of migraine was made according to the classification proposed by the International Headache Society. The method of visual evoked potential was performed with pattern reversal (VEP-PR, with monocular stimulation. The stimulation was performed with pattern reversal with 4x4 cm black and white and red and green squared screen placed 1 meter from the nasion at stimulus frequency 1/s; 128 individual trials were analysed. The VEP-PR with black/white and red/green study showed a significant increase of value of the P-100 latency in 10 migraine patients. In 8 cases the LP100 in VEP-PR black/white was normal but in VEP-PR red/green the LP100 showed increase. Specifically in 1 of our cases, LP100 were normal in VEP-PR black/white but in the red/green there were no reproductice waves. On basis of these observations we consider that the method of VEP-PR is an useful instrument for investigation of migraine patients without aura.

  19. Effect of pupil size on multifocal pattern visual evoked potentials. (United States)

    Martins, Alessandra; Balachandran, Chandra; Klistorner, Alexander I; Graham, Stuart L; Billson, Francis A


    The purpose of this study was to investigate the influence of pupil diameter on the amplitude and latency of multifocal visual evoked potentials (mfVEP). The multifocal objective perimeter (Accumap; Objectivision) was used to stimulate the visual field at 56 sites extending to 32 degrees using a pseudo-random pattern stimulus. The mfVEP were recorded using bipolar occipital electrodes, 7 min/eye. Ten normal subjects were recruited from the community and one eye was randomly selected for testing. The mfVEP were recorded at four different pupil diameters (2 mm, 4 mm, 6 mm, 8 mm), obtained by applying tropicamide (0.5%) or pilocarpine (2%) in different dilutions. Appropriate refractive correction was provided to overcome cycloplegia and achieve a visual acuity of 6/7.5 or better. Analysis revealed that at most pupil diameters the normalized full field amplitude did not show significant variation, except at the most miotic pupil diameter (2 mm), where the amplitude became reduced, based on 2-way anova and Tukey's T method. There was, however, significant correlation between latency and pupil area (correlation coefficient: upper field -0.63, lower field -0.76). The results suggest that even in the presence of mydriatics or miotics, the mfVEP test can be used to assess diseases that affect amplitude, provided near correction is used. The interpretation of latency, however, must be made with caution, as a borderline conduction defect with a dilated pupil may appear normal.

  20. Software for analysing multifocal visual evoked potential signal latency progression. (United States)

    de Santiago, L; Klistorner, A; Ortiz, M; Fernández-Rodríguez, A J; Rodríguez Ascariz, J M; Barea, R; Miguel-Jiménez, J M; Boquete, L


    This paper describes a new non-commercial software application (mfVEP(2)) developed to process multifocal visual-evoked-potential (mfVEP) signals in latency (monocular and interocular) progression studies. The software performs analysis by cross-correlating signals from the same patients. The criteria applied by the software include best channels, signal window, cross-correlation limits and signal-to-noise ratio (SNR). Software features include signal display comparing different tests and groups of sectors (quadrants, rings and hemispheres). The software's performance and capabilities are demonstrated on the results obtained from a patient with acute optic neuritis who underwent 9 follow-up mfVEP tests. Numerical values and graphics are presented and discussed for this case. The authors present a software application used to study progression in mfVEP signals. It is also useful in research projects designed to improve mfVEP techniques. This software makes it easier for users to manage the signals and allows them to choose various ways of selecting signals and representing results. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Effect of stimulus check size on multifocal visual evoked potentials. (United States)

    Balachandran, Chandra; Klistorner, Alexander I; Graham, Stuart L


    In this study we examined the effects of varying stimulus check size on multifocal visual evoked potential (VEP). We also evaluated the currently used cortical scaling of stimulus segments. The ObjectiVision multifocal objective perimeter stimulates the eye with random check patterns at 56 cortically scaled segments within the visual field extending to a radius of 26 degrees. All cortically scaled segments have equal number of checks, which gradually increase in size from the center to the periphery, proportional to the size of the segment. Stimuli with 9, 16, 25, 36 and 49 checks/segment were tested on 10 eyes belonging to 10 normal subjects. The check size varied inversely with number of checks per segment. VEP was recorded using bipolar occipital cross electrodes (7 min/eye), the amplitude and latency of responses obtained were compared with the check size at different eccentricities. Our findings suggest that the existing setting with 16 checks/segment subtending 26' to 140' from center to periphery, is the most effective amongst all the check sizes. Decreasing the check size prolongs the latency in the central field only. Cortical scaling of segments generates responses of the same order of magnitude throughout the field, but could be improved slightly to enhance the signal from the outer two rings.

  2. Pattern Visual Evoked Potentials Elicited by Organic Electroluminescence Screen

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    Celso Soiti Matsumoto


    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.

  3. Contrast Sensitivity versus Visual Evoked Potentials in Multiple Sclerosis

    Directory of Open Access Journals (Sweden)

    Javad Heravian Shandiz


    Full Text Available Purpose: To compare the Cambridge contrast sensitivity (CS test and visual evoked potentials (VEP in detecting visual impairment in a population of visually symptomatic and asymptomatic patients affected by clinically definite multiple sclerosis (MS. Methods: Fifty patients (100 eyes presenting with MS and 25 healthy subjects (50 eyes with normal corrected visual acuity were included in this study. CS was determined using the Cambridge Low Contrast Grating test and VEP was obtained in all eyes. Findings were evaluated in two age strata of 10-29 and 30-49 years. Results: Of the 42 eyes in the 10-29 year age group, CS was abnormal in 22 (52%, VEP was also abnormal in 22 (52%, but only 12 eyes (28% had visual symptoms. Of the 58 eyes in the 30-49 year group, CS was abnormal in 7 (12%, VEP was abnormal in 34 (58%, while only 11 eyes were symptomatic. No single test could detect all of the abnormal eyes. Conclusion: The Cambridge Low Contrast Grating test is useful for detection of clinical and subclinical visual dysfunction especially in young patients with multiple sclerosis. Nevertheless, only a combination of CS and VEP tests can detect most cases of visual dysfunction associated with MS.

  4. Grating-evoked cortical potentials and perceived contrast (A) (United States)

    Strasburger, Hans; Scheidler, Wolfgang; Rentschler, Ingo

    Unlike subjective perception of contrast, steady-state evoked cortical potentials (VEP's) elicited with counterphased gratings may vary abruptly with changes in spatial frequency.(1) To avoid possible artifacts we developed a digital fast-sweep technique for investigating this discrepancy. In most of our 13 subjects, at high stimulus contrasts the dependency of VEP amplitude on spatial frequency had two pronounced peaks separated by a sharp notch at around 3 cycles per degree. With decreasing contrast these variations leveled out, and a unimodal response function was obtained at low contrast. A linear relationship between log contrast and VEP amplitude(2) was found for any given spatial frequency only in the low-contrast range. With increasing contrast the VEP amplitude saturated at a rate that depended clearly on spatial frequency, with a nonmonotonous dependency occurring at intermediate spatial frequencies. The latter phenomenon of oversaturation apparently gave rise to the above-mentioned bimodal response characteristic. Results of a careful analysis of VEP phase lags are added. (1) C. W. Tyler et al., Brain Res. 33, 535 (1978). (2) F. W. Campbell and L. Maffei, J. Physiol. 207, 635 (1970).

  5. Changes of Transient Visual Evoked Potentials in Dyslexic Children

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    Ka Yan Leung


    Full Text Available Objectives: To investigate the characteristics of Visual Evoked Potentials (VEP in dyslexics. Methods: Fourteen children, 7 dyslexics and 7 control, aged 7 to 8 years were recruited. All dyslexic subjects were diagnosed by clinical psychologist. All subjects are from mainstream primary schools in Hong Kong, using Chinese and Cantonese as their primary written and spoken language, having normal visual acuity and IQ. Children with reported emotional or behavioral problems or binocular vision problem were excluded. All the subjects participated in pattern-reversal VEP measurements binocularly with 1000msec recording time. Four conditions of stimulations (checkersize: 180 min of arc were applied. (15-Hz at 15% contrast (25-Hz at 1% contrast (315-Hz at 15% contrast (415-Hz at 1% contrast Results: At 15% contrast stimulus, dyslexic subjects showed smaller amplitudes in both frequencies compared with the control group, especially in higher frequency. At 1% contrast stimulus, dyslexic subjects also showed smaller amplitudes in both frequencies and obvious reduction was observed at the later part of the recording period. No observable difference was showed in the latency of both contrast conditions. Conclusion: The attenuated VEP responses in higher frequency at low contrast condition in dyslexic group showed the changes of the transient visual response and this implies an abnormality in magnocellular pathway in dyslexia.

  6. Flash visual evoked potentials in diurnal birds of prey

    Directory of Open Access Journals (Sweden)

    Maurizio Dondi


    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.

  7. Event-related evoked potentials in chronic respiratory encephalopathy

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    A R Al Tahan


    Full Text Available A R Al Tahan1, R Zaidan1, S Jones2, A Husain3, A Mobeireek1, A Bahammam11Department of Medicine, 3Department of Physiology, College of Medicine, King Saud University, Riyadh, Saudi Arabia; 2Department of Neurophysiology, Institute of Neurology, London, UKBackground: Cognitive event-related potential (P300 is an index of cognitive processing time. It was found to be prolonged in dementia, renal, and hepatic encephalopathies, but was not extensively assessed in respiratory failure.Objective: To evaluate P300 changes in patients with respiratory failure, and especially those with mild or subclinical hypoxic–hypercapnic encephalopathy.Methods: Auditory event-related evoked potential P300 latency was measured using an oddball paradigm in patients with respiratory failure due to any cause (partial pressure of oxygen in arterial blood (PO2 should be 75 mm/Hg or less. Apart from blood gases measurement, patients underwent the Mini-Mental State Examination (MMSE. Patient performances were compared with that of matched normal control. Patients were admitted into the study from outpatient clinics and wards at King Khalid University Hospital and Sahara Hospital.Results: Thirty-four patients (12 women, 22 men were admitted to the study. Ages ranged from 19–67 years with a mean of 46.1 years. Respiratory failure was severe or very severe in 11 patients (33%, and mild or moderate in the rest (66%. Mean value for PO2 and partial pressure of carbon dioxide in arterial blood (PCO2 were 63.7 and 45.2 mm/Hg, respectively. pH mean was 7.4 and O2 saturation was 90.7%. P300 latency ranged from 218 to 393 milliseconds, with a mean of 338.4 milliseconds. In comparison with control (309.9 milliseconds, there was a significant difference (P = 0.007. P300 amplitude differences were not significant. No significant difference in MMSE was noted between mild and severe respiratory failure. Results of detailed neuropsychological assessment were clearly abnormal but were

  8. 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.


    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...

  9. Paying attention to orthography: A visual evoked potential study

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    Anthony Thomas Herdman


    Full Text Available In adult readers, letters and words are rapidly identified within visual networks to allow for efficient reading abilities. Neuroimaging studies of orthography have mostly used words and letter strings that recruit many hierarchical levels in reading. Understanding how single letters are processed could provide further insight into orthographic processing. The present study investigated orthographic processing using single letters and pseudoletters when adults were encouraged to pay attention to or away from orthographic features. We measured evoked potentials (EPs to single letters and pseudoletters from adults while they performed an orthographic-discrimination task (letters vs. pseudoletters, a colour-discrimination task (red vs. blue, and a target-detection task (respond to #1 and #2. Larger and later peaking N1 responses (~170ms and larger P2 responses (~250 ms occurred to pseudoletters as compared to letters. This reflected greater visual processing for pseudoletters. Dipole analyses localized this effect to bilateral fusiform and inferior temporal cortices. Moreover, this letter-pseudoletter difference was not modulated by task and thus indicates that directing attention to or away from orthographic features didn’t affect early visual processing of single letters or pseudoletters within extrastriate regions. Paying attention to orthography or colour as compared to disregarding the stimuli (target-detection task elicited selection negativities at about 175 ms, which were followed by a classical N2-P3 complexes. This indicated that the tasks sufficiently drew participant’s attention to and away from the stimuli. Together these findings revealed that visual processing of single letters and pseudoletters, in adults, appeared to be sensory-contingent and independent of paying attention to stimulus features (e.g., orthography or colour.

  10. Age and gender effects on submental motor-evoked potentials. (United States)

    Sella, Oshrat; Jones, Richard D; Huckabee, Maggie-Lee


    It is not known whether there are age- and/or gender-related differences in magnitude of motor-evoked potentials (MEPs) of the submental muscles. Knowledge of this is important in investigations of neurophysiological aspects of swallowing. Forty healthy participants (20 males, 20 females; 20 young [21-35 years], 20 old [53-88 years]) were recruited. Surface electromyography (EMG) electrodes were placed at midline underlying the submental muscle group. Age- and gender-related differences were evaluated in two neurophysiologic measures of swallowing: MEPs stimulated by single-pulse transcranial magnetic stimulation (TMS) over the motor cortex and surface electromyography (sEMG) recorded from the same submental muscle group during non-stimulated swallows. The older participants had larger MEPs during saliva swallowing than the young participants (p = 0.04, d = 0.86). Conversely, the older participants had lower amplitude submental EMG activity during non-stimulated swallows (p = 0.045, d = 0.67). Gender had no significant effect on MEP magnitude and on submental activity during saliva swallowing. There were no effects of age or gender on MEP latencies. These findings suggest deterioration in muscle function with age in a sample of healthy adults presenting with functional swallowing. We speculate that muscular decline is partially ameliorated by increased cortical activity-i.e., increased submental MEPs-so as to preserve swallowing function in healthy older subjects. These findings emphasize the need for different reference points for evaluation of submental MEPs of different age groups.

  11. Brainstem auditory-evoked potential in Boxer dogs

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    Mariana Isa Poci Palumbo


    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.

  12. Vestibular-evoked myogenic potentials in central vestibular disorders. (United States)

    Oh, Sun-Young; Kim, Hyo-Jeong; Kim, Ji-Soo


    Vestibular-evoked myogenic potentials (VEMPs) are short latency manifestations of vestibulo-ocular and vestibulocollic reflexes that originate from the utricle and saccule. Although cervical and ocular VEMPs have mostly been applied to peripheral vestibular disorders, the characteristics and the diagnostic values of VEMPs have been expanded to assess the function of the central otolithic pathways. In the central nervous system, the cervical VEMPs (cVEMPs) are mediated by the vestibular nuclei and uncrossed medial vestibulospinal tract descending in the lower brainstem and spinal cord. In contrast, the ocular VEMPs (oVEMPs) reflect the function of the vestibular nuclei and the crossed vestibulo-ocular reflex (VOR) pathways, mostly contained in the medial longitudinal fasciculus (MLF). Therefore, lesions involving the vestibular nuclei can present abnormalities of both cVEMPs and oVEMPs. The medullary lesions involving the descending MLF or the spinal accessory nucleus impair cVEMPs. In contrast, the lesions involving the MLF, the crossed ventral tegmental tract, oculomotor nuclei and the interstitial nucleus of Cajal can impair oVEMPs. Patients with unilateral cerebellar infarctions may show abnormal VEMPs especially when they have the ocular tilt reaction. Delayed responses of VEMPs are characteristic of multiple sclerosis (MS). Reduced VEMP responses can be observed in patients with vestibular migraine. VEMPs are useful in evaluating central as well as peripheral otolithic function that are not readily defined by conventional vestibular function tests, and can aid in detecting and localizing central lesions, especially silent brainstem lesions such as tiny infarctions or MS plaques.

  13. Ocular vestibular evoked myogenic potentials in normal-hearing adults

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    Mohammad Kamali


    Full Text Available Background and Aim: Ocular vestibular-evoked myogenic potential (oVEMP is a novel vestibular function test. This short-latency response can be recorded through contracting extraocular muscles by high-intensity acoustic stimulation and can be used to evaluate contralateral ocular-vestibular reflex. The aim of this study was to record and compare the amplitude, latency, asymmetry ratio and occurrence percentage of oVEMP (n10 and cervical VEMP (p13 responses in a group of normal adult subjects.Methods: We carried out a cross-sectional study on 20 adult subjects' mean age 22.18 years, SD=2.19 with normal hearing sensitivity and no history of vestibular diseases. oVEMP and cVEMP responses in both ears were recorded using air conducted stimuli 500 Hz short tone burst, 95 dB nHL via insert earphone and compared.Results: cVEMP was recorded in all subjects but oVEMP was absent in two subjects. Mean amplitude and latency were 140.77 μv and 15.56 ms in p13; and 3.18 μv and 9.32 ms in n10. There were statistically significant differences between p13 and n10 amplitudes (p<0.001.Conclusion: This study showed that occurrence percentage and amplitude of oVEMP were less than those of cVEMP. Since these two tests originate from different sections of vestibular nerve, we can consider them as parallel vestibular function tests and utilize them for evaluation of vestibular disorders.

  14. Effect of fixation tasks on multifocal visual evoked potentials. (United States)

    Martins, Alessandra; Klistorner, Alexander; Graham, Stuart; Billson, Frank


    This study investigated the effects of cognitive influence on the multifocal visual evoked potential (mVEP) at different levels of eccentricity. Three different foveal fixation conditions were utilized involving varying levels of task complexity. A more complex visual fixation task has been known to suppress peripheral signals in subjective testing. Twenty normal subjects had monocular mVEPs recorded using the AccuMap objective perimeter. This allowed simultaneous stimulation of 58 segments of the visual field to an eccentricity of 24 degrees. The mVEP was recorded using three different fixation conditions in random order. During task 1 the subject passively viewed the central fixation area. For task 2 alternating numbers were displayed within the fixation area; the subject on viewing the number '3' in the central fixation area indicated recognition by pressing a button. Throughout task 3, numbers were displayed as in task 2. The subject had the cognitive task of summating all the numbers. Analysis revealed that the increased attention and concentration demanded by tasks 2 and 3 in comparison with task 1 resulted in significantly enhanced central amplitudes of 9.41% (Mann-Whitney P = 0.0002) and 13.45% (P = 0.0002), respectively. These amplitudes became reduced in the periphery and approached those of task 1, resulting in no significant difference between the three tasks. Latencies demonstrated no significant difference between each task nor at any eccentricity (P > 0.05). As the complexity of each task increased the amount of alpha rhythm was significantly reduced. Our findings indicate that task 1 required a minimal demand of cognition and was associated with the greatest amount of alpha rhythm. It was also the most difficult to perform because of loss of interest. The other two tasks required a greater demand of higher order cognitive skills resulting in significantly enhanced amplitudes centrally and the attenuation of alpha rhythm. Therefore, amplitudes are

  15. Visual evoked potentials in subgroups of migraine with aura patients. (United States)

    Coppola, Gianluca; Bracaglia, Martina; Di Lenola, Davide; Di Lorenzo, Cherubino; Serrao, Mariano; Parisi, Vincenzo; Di Renzo, Antonio; Martelli, Francesco; Fadda, Antonello; Schoenen, Jean; Pierelli, Francesco


    Patients suffering from migraine with aura can have either pure visual auras or complex auras with sensory disturbances and dysphasia, or both. Few studies have searched for possible pathophysiological differences between these two subgroups of patients. Methods - Forty-seven migraine with aura patients were subdivided in a subgroup with exclusively visual auras (MA, N = 27) and another with complex neurological auras (MA+, N = 20). We recorded pattern-reversal visual evoked potentials (VEP: 15 min of arc cheques, 3.1 reversal per second, 600 sweeps) and measured amplitude and habituation (slope of the linear regression line of amplitude changes from the 1st to 6th block of 100 sweeps) for the N1-P1 and P1-N2 components in patients and, for comparison, in 30 healthy volunteers (HV) of similar age and gender distribution. VEP N1-P1 habituation, i.e. amplitude decrement between 1st and 6th block, which was obvious in most HV (mean slope -0.50), was deficient in both MA (slope +0.01, p = 0.0001) and MA+ (-0.0049, p = 0.001) patients. However, VEP N1-P1 amplitudes across blocks were normal in MA patients, while they were significantly greater in MA+ patients than in HVs. Our findings suggest that in migraine with aura patients different aura phenotypes may be underpinned by different pathophysiological mechanisms. Pre-activation cortical excitability could be higher in patients with complex neurological auras than in those having pure visual auras or in healthy volunteers.

  16. Diagnostic accuracy of laser evoked potentials in diabetic neuropathy. (United States)

    Di Stefano, G; La Cesa, S; Leone, C; Pepe, A; Galosi, E; Fiorelli, M; Valeriani, M; Lacerenza, M; Pergolini, M; Biasiotta, A; Cruccu, G; Truini, A


    Although the most widely agreed neurophysiological tool for investigating small fibre damage is laser evoked potential (LEP) recording, no study has documented its diagnostic accuracy. In this clinical, neurophysiological and skin biopsy study we collected age-corrected LEP normative ranges, verified the association of LEPs with pinprick sensory disturbances in the typical diabetic mixed-fibre polyneuropathy and assessed the sensitivity and specificity of LEPs in diabetic small-fibre neuropathy.From 288 LEP recordings from the face, hand and foot in 73 healthy subjects we collected age-corrected normative ranges for LEPs. We then selected 100 patients with mixed-fibre diabetic neuropathy and 25 patients with possible small-fibre diabetic neuropathy. In the 100 patients with mixed-fibre neuropathy we verified how LEP abnormalities were associated with clinically evident pinprick sensory disturbances. In the 25 patients with possible pure small-fibre neuropathy, using the skin biopsy for assessing the intraepidermal nerve fibre density, as a reference standard, we calculated LEP sensitivity and specificity.In healthy participants, age strongly influenced normative ranges for all LEP variables. By applying age-corrected normative ranges for LEPs, we found that LEPs were strongly associated with pinprick sensory disturbances. In relation to the skin biopsy findings, LEPs yielded 78% sensitivity and 81% specificity in the diagnosis of diabetic small-fibre neuropathy.Our study, providing age-corrected normative ranges for the main LEP data and their diagnostic accuracy, helps to make LEPs more reliable as a clinical diagnostic tool, and proposes this technique as a less invasive alternative to skin biopsy for diagnosing diabetic small-fibre neuropathy.

  17. Visual function with acupuncture tested by visual evoked potential. (United States)

    Sagara, Yoshiko; Fuse, Nobuo; Seimiya, Motohiko; Yokokura, Syunji; Watanabe, Kei; Nakazawa, Toru; Kurusu, Masayuki; Seki, Takashi; Tamai, Makoto


    Visual evoked potential (VEP) testing is used frequently and is an important ophthalmologic physiological test to examine visual functions objectively. The VEP is a complicated waveform consisting of negative waveform named N75 and N135, and positive waveform named P100. Delayed P100 latency and greatly attenuated amplitude on VEP are known characteristics for diagnosing optic nerve disease. Acupuncture has been used to treat wide clinical symptoms with minimal side effects. The confirmation of the efficacy of acupuncture generally relies on subjective symptoms. There is not much scientific evidence supporting the acupuncture treatments for eye diseases up to today. However, the VEP test can evaluate objectively and numerically the efficacy of the treatment by the acupuncture. We analyzed 19 healthy subjects (38 eyes). The P100 latencies in the group of less than 101.7 msec (total average) before acupuncture stimulations were not different than those after treatment (98.2 +/- 3.0 msec, 98.2 +/- 4.0 msec, respectively, p = 0.88, n = 17), but the latencies in those subjects with longer or equal to 101.7 msec were statistically different after acupuncture (104.6 +/- 2.8 msec, 101.9 +/- 3.7 msec, respectively, p = 0.006, n = 21). These results show that the acupuncture stimulation contributes to the P100 latencies of pattern reversal (PR)-VEP to some subjects who have delayed latencies, and this electrophysiological method is a valuable technique in monitoring the effectiveness of acupuncture therapy in the improvements of visual functions. The purpose of this study is to evaluate the physiological effects by acupuncture stimulations using PR-VEP in normal subjects.

  18. Brain stem auditory evoked responses in human infants and adults (United States)

    Hecox, K.; Galambos, R.


    Brain stem evoked potentials were recorded by conventional scalp electrodes in infants (3 weeks to 3 years of age) and adults. The latency of one of the major response components (wave V) is shown to be a function both of click intensity and the age of the subject; this latency at a given signal strength shortens postnatally to reach the adult value (about 6 msec) by 12 to 18 months of age. The demonstrated reliability and limited variability of these brain stem electrophysiological responses provide the basis for an optimistic estimate of their usefulness as an objective method for assessing hearing in infants and adults.

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

    NARCIS (Netherlands)

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


    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

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

    NARCIS (Netherlands)

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


    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

  1. Normalization of visual evoked potentials using underlying electroencephalogram levels improves amplitude reproducibility in rats. (United States)

    You, Yuyi; Thie, Johnson; Klistorner, Alexander; Gupta, Vivek K; Graham, Stuart L


    The visual evoked potential (VEP) is a frequently used noninvasive measurement of visual function. However, high-amplitude variability has limited its potential for evaluating axonal damage in both laboratory and clinical research. This study was conducted to improve the reliability of VEP amplitude measurement in rats by using electroencephalogram (EEG)-based signal correction. VEPs of Sprague-Dawley rats were recorded on three separate days within 2 weeks. The original VEP traces were normalized by EEG power spectrum, which was evaluated by Fourier transform. A comparison of intersession reproducibility and intersubject variability was made between the original and corrected signals. Corrected VEPs showed lower amplitude intersession within-subject SD (Sw), coefficient of variation (CoV), and repeatability (R(95)) than the original signals (P < 0.001). The intraclass correlation coefficient (ICC) of the corrected traces (0.90) was also better than the original potentials (0.82). For intersubject variability, the EEG-based normalization improved the CoV from 44.64% to 30.26%. A linear correlation was observed between the EEG level and the VEP amplitude (r = 0.71, P < 0.0001). Underlying EEG signals should be considered in measuring the VEP amplitude. In this study, a useful technique was developed for VEP data processing that could also be used for other cortical evoked potential recordings and for clinical VEP interpretation in humans.

  2. Exploring the Mechanisms of Exercise-Induced Hypoalgesia Using Laser Evoked Potentials

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    Matthew David Jones


    Full Text Available Exercise-induced hypoalgesia is well described, but the underlying mechanisms are unclear. The aim of this study was to examine the effect of exercise on somatosensory evoked potentials, laser evoked potentials, pressure pain thresholds and heat pain thresholds. These were recorded before and after 3-min of isometric elbow flexion exercise at 40% of the participant’s maximal voluntary force, or an equivalent period of rest. Exercise-induced hypoalgesia was confirmed in two experiments (Experiment 1 – SEPs; Experiment 2 – LEPs by increased pressure pain thresholds at biceps brachii (24.3% and 20.6% increase in Experiment 1 and 2, respectively; both d > 0.84 and p 0.57 and p < 0.001. In contrast, heat pain thresholds were not significantly different after exercise (forearm: 10.8% increase, d = 0.35, p = 0.10; hand: 3.6% increase, d = 0.06, p = 0.74. Contrasting effects of exercise on the amplitude of laser evoked potentials (14.6% decrease, d = -0.42, p = 0.004 and somatosensory evoked potentials (10.9% increase, d = -0.02, p = 1.72 were also observed, while an equivalent period of rest showed similar habituation (laser evoked potential: 7.3% decrease, d = -0.25, p = 0.14; somatosensory evoked potential: 20.7% decrease, d = -0.32, p = 0.006. The differential response of pressure pain thresholds and heat pain thresholds to exercise is consistent with relative insensitivity of thermal nociception to the acute hypoalgesic effects of exercise. Conflicting effects of exercise on somatosensory evoked potentials and laser evoked potentials were observed. This may reflect non-nociceptive contributions to the somatosensory evoked potential, but could also indicate that peripheral nociceptors contribute to exercise-induced hypoalgesia.

  3. [Auditory evoked potential and personality traits in chronic primary insomniacs]. (United States)

    Shen, Jian; Shui, Ren-de; Feng, Lei; Liu, Yu-Hong; He, Wei; Huang, Jing-Yi; Wang, Wei


    To investigate the personality traits and intensity dependence of auditory evoked potentials (AEPs) in chronic primary insomnia. Thirty-seven patients with chronic primary insomnia (insomnia group) and 44 healthy subjects (control group) were enrolled in the study. The AEPs were examined in insomnia and control groups; the personality traits were studied by Zuckerman's Sensation Seeking Scales (SSS) and Zuckerman-Kuhlman's Personality Questionnaire (ZKPQ); and the mood states by Plutchik-van Praag's Depression Inventory (PVP). The scores of neuroticism-anxiety and depression in insomnia group were significantly higher than those in control group (P<0.01); and the scores of impulsivity and aggression-hostility were also higher than those in control group (P<0.05); N1-P2 amplitude of AEP increased with stimulus intensity, which were significantly different in 70, 80, 90,100 dB (P<0.01). There were significant correlations between activity and N1 latency at 80 dB, activity and P2 latency at 100 dB (r=0.270, r=0.276, P<0.05); and between total scores of sensation seeking scale and N1-P2 amplitude (r=0.3746, r=0.35329, P<0.01) at 70 and 90 dB stimulus intensity in insomnia group. There were significant correlations among experience seeking and N1-P2 amplitude, experience seeking and slope rate (P<0.01) at 70, 80, 90, 100 dB stimulus intensity in insomnia group (r=0.539, r=0.3439, r=0.439, r=0.3278). There were significant correlations between sensation seeking of boredom susceptibility and slope rate (r=-0.282998, P<0.05) in insomnia group. There were significant correlations between thrill and adventure seeking and N1-P2 amplitude(r=0.2789, P<0.05) at 90 dB stimulus intensity in insomnia group; there were significant correlations between PVP and N1-P2 amplitude (r=-0.3434, r=-0.3158, P<0.05) at 70 dB and N1 latency at 80 dB in insomnia group. Chronic primary insomnia sufferers have higher levels of neuroticism-anxiety, depression, aggression-hostility and impulsivity

  4. The utility of multimodal evoked potentials in multiple sclerosis prognostication. (United States)

    Ramanathan, Sudarshini; Lenton, Kerry; Burke, Therese; Gomes, Lavier; Storchenegger, Karen; Yiannikas, Con; Vucic, Steve


    The ability to predict disability development in multiple sclerosis (MS) is limited. While abnormalities of evoked potentials (EP) have been associated with disability, the prognosticating utility of EP in MS remains to be fully elucidated. The present study assessed the utility of multimodal EP as a prognostic biomarker of disability in a cohort of clinically heterogeneous MS patients. Median and tibial nerve somatosensory, visual, and brainstem auditory EP were performed at initial assessment on 63 MS patients (53 relapsing-remitting and 10 secondary progressive) who were followed for an average of 2 years. A combined EP score (CEPS) was calculated consisting of the total number of abnormal EP tests, and was correlated with the Expanded Disability Status Scale (EDSS) at baseline and follow-up. There was a significant correlation between multimodal EP and baseline and follow-up EDSS. Specifically, tibial nerve P37 latencies correlated with EDSS (R(BASELINE)=0.49, p<0.01; R(FOLLOW-UP)=0.47, p<0.01), as did the median nerve N13 (R(BASELINE)=0.40, p<0.01; R(FOLLOW-UP)=0.35, p<0.05) and N20 latencies (R(BASELINE)=0.43, p<0.01; R(FOLLOW-UP)=0.47, p<0.01), and P100 full-field (R(BASELINE)=0.50, p<0.001; R(FOLLOW-UP)=0.45, p<0.001) and central field latencies (R(BASELINE)=0.60, p<0.001; R(FOLLOW-UP)=0.50, p<0.001). In addition, there was a significant correlation between the CEPS with baseline (R=0.65, p<0.001) and follow-up (R=0.57, p<0.01) EDSS. In contrast, white matter disease burden, as measured by T2 lesion load, exhibited a weaker correlation with EDSS (R(BASELINE)=0.28, p<0.05). In conclusion, these findings suggest that abnormalities of EP, as quantified by the novel CEPS, may be a useful biomarker for prognosticating clinical disability in MS, and may aid in the quantification of MS disease severity and in guiding therapeutic decisions.

  5. Evoked potentials in immobilized cats to a combination of clicks with painful electrocutaneous stimuli (United States)

    Gilinskiy, M. A.; Korsakov, I. A.


    Averaged evoked potentials in the auditory, somatosensory, and motor cortical zones, as well as in the mesencephalic reticular formation were recorded in acute experiments on nonanesthetized, immobilized cats. Omission of the painful stimulus after a number of pairings resulted in the appearance of a delayed evoked potential, often resembling the late phases of the response to the painful stimulus. The characteristics of this response are discussed in comparison with conditioned changes of the sensory potential amplitudes.

  6. The cortical spatiotemporal correlate of otolith stimulation: vestibular evoked potentials by body translations. (United States)

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


    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.

  7. The temporal relationship between the brainstem and primary cortical auditory evoked potentials. (United States)

    Shaw, N A


    Many methods are employed in order to define more precisely the generators of an evoked potential (EP) waveform. One technique is to compare the timing of an EP whose origin is well established with that of one whose origin is less certain. In the present article, the latency of the primary cortical auditory evoked potential (PCAEP) was compared to each of the seven subcomponents which compose the brainstem auditory evoked potential (BAEP). The data for this comparison was derived from a retrospective analysis of previous recordings of the PCAEP and BAEP. Central auditory conduction time (CACT) was calculated by subtracting the latency of the cochlear nucleus BAEP component (wave III) from that of the PCAEP. It was found that CACT in humans is 12 msec which is more than double that of central somatosensory conduction time. The interpeak latencies between BAEP waves V, VI, and VII and the PCAEP were also calculated. It was deduced that all three waves must have an origin rather more caudally within the central auditory system than is commonly supposed. In addition, it is demonstrated that the early components of the middle latency AEP (No and Na) largely reside within the time domain between the termination of the BAEP components and the PCAEP which would be consistent with their being far field reflections of midbrain and subcortical auditory activity. It is concluded that as the afferent volley ascends the central auditory pathways, it generates not a sequence of high frequency BAEP responses but rather a succession of slower post-synaptic waves. The only means of reconciling the timing of the BAEP waves with that of the PCAEP is to assume that the generation of all the BAEP components must be largely restricted to a quite confined region within the auditory nerve and the lower half of the pons.

  8. Computer Processing of Visual Evoked Potentials Utilizing Digital Filtering Techniques


    Vigorito, A.; Stephens, G.; Louis, H; Cinotti, A.; Michelson, L.; E. Stephens


    Recording of the VER (Visual Evoked Response) and the ERG (ElectroRetinoGram) in our laboratory is done with stimulation, using a fixed checkerboard pattern or a reversible checkerboard pattern. Questionable data frames are eliminated from the signal averaging process by means of a semiautomatic electronic analyzer or by means of a computer program. This special computer software, with flexible format constraints, is utilized on an off-line basis to remove residual artifacts and noise from av...

  9. Comparison Acoustically Evoked Short Latency Negative Response with Vestibular Evoked Myogenic Potential in Adults with Profound Hearing Loss

    Directory of Open Access Journals (Sweden)

    Maryam Ramezani


    Full Text Available Background and Aim: A negative deflection with a 3-4 ms latency period has been reported to exist within the auditory brainstem response of some patients with profound hearing loss following a strong acoustic stimulus. This deflection, namingly the n3 or the acoustically evoked short latency negative response is assumed to be a vestibular-evoked potential, especially of saccular origin. Since the myogenic potential is also saccular in origin, the purpose of the present study was to investigate the relationship between these two tests in adults with profound hearing loss.Methods: The present cross sectional study was performed on 20 profoundly deaf volunteers(39 ears who aged between 18-40 years old, randomly selected from available deaf adults in Tehran. The auditory brainstem response of all subjects was recorded following a 1000 Hz tone burst in 70-100dB nHL. Subjects were also tested for vestibular evoked myogenic potential.Results: Only 34 of 39 ears recorded myogenic potential that negative response was recorded in 27 of 34 ears with normal p13 and n23. In seven ears with normal p13 and n23, the negative response was absent. In 3 ears with no p13 and n23, the negative response was observed, and two none.Conclusion: In view of the high prevalance of the negative response in profoundly deaf ears with normal p13 and n23, it could be concluded that the negative response can be used when for any reason, it is not possible to record myogenic potential and be considered as a new test in vestibular test battery.

  10. Short latency vestibular potentials evoked by electrical round window stimulation in the guinea pig. (United States)

    Bordure, P; Desmadryl, G; Uziel, A; Sans, A


    Short-latency potentials evoked by round window electrical stimulation were recorded in guinea pig by means of vertex-pinna skin electrodes using averaging techniques. Constant current shocks of 20 microseconds or 50 microseconds (25-300 microA) were used to evoke both auditory and vestibular brain-stem potentials. Pure auditory potentials, comparable to those evoked by acoustic clicks, were obtained by 20 microseconds electrical stimuli and disappeared during an auditory masking procedure made with a continuous white noise (110 dB SPL). Short latency potentials labeled V1, V2 and V3 were obtained by 50 microseconds electrical stimuli during an auditory masking procedure. This response disappeared after specific vestibular neurectomy, whereas the auditory response evoked by acoustic clicks or by electrical stimulation remained unchanged, suggesting that these latter potentials had a vestibular origin.

  11. 低频电刺激对健康成年人体感和运动诱发电位的影响%Effects of Low-frequency Electrical Stimulation on Sense and Motor Evoked Potentials of Healthy Adult Human

    Institute of Scientific and Technical Information of China (English)

    向云; 尉洋


    Objective: to observe the effects of low-frequency electrical stimulation (LES) on healthy adult with somatosensory evoked potential (SEP) and motor evoked potential (MEP). Method: 25 healthy adults (thirteen males and twelve females, with a mean age of 42.9 and a standard deviation of 5.7) participated in the study. SEP and MEP were measured before and after the LES stimulation. Results: After LES, the latency of SEP and MEP for the stimulated side became shorter and the amplitude became greater. These changes in latency and amplitude were statistically significant (P<0.05). For the unstimulated side, the changes of SEP and MEP did not show statistically significant difference. Conclusion: The SEP and MEP parameters, especially the amplitude, can be used to evaluate the effect of LES on central nervous system (CNS).%  目的:观察低频电刺激(Low-frequency Electrical Stimulation,LES)对健康成年人体感诱发电位(Somatosensory Evoked Potential,SEP)及运动诱发电位(Motor Evoked Potential,MEP)的影响。方法:入选25例健康成年人(男13例,女12例,平均年龄42.9±5.7岁),采用经颅磁刺激仪(TMS)及肌电图仪,分别测量 LES 刺激前后 SEP 值及 MEP 值。结果:健康成年人 LES 刺激后 SEP 及 MEP 值的潜伏期缩短、波幅增高,与刺激前比较,差异有统计学意义(P<0.05);非刺激侧无明显变化。结论:健康成年人 LES 刺激前后 SEP 及 MEP 参数值均有显著性变化,尤以波幅明显,提示电刺激对中枢神经系统存在作用。

  12. Occipital cortex activation studied with simultaneous recordings of functional transcranial Doppler ultrasound (fTCD) and visual evoked potential (VEP) in cognitively normal human subjects: effect of healthy aging. (United States)

    Topcuoglu, M Akif; Aydin, Hulya; Saka, Esen


    We evaluated effect of aging, gender and eye (sighting) dominance on relationship between visual evoked flow response (VEFR) and visual evoked potential (VEP), which refers to neurovascular coupling. The VEFR was defined as a percentage increase of the ratio of mean blood flow velocity in the contralateral (according to the side of dominant eye processing) posterior cerebral artery P2 segment to those in ipsilateral middle cerebral artery from the baseline during half-field stimulation. Vasoneural coupling index (CI) was defined as "100 x VEFR/VEP P100 amplitude". Compared to the healthy elderly subjects (n: 19; female/male: 6/13, mean age: 69.7 +/- 7), younger participants (n: 28; female/male: 16/12; mean age: 31.1 +/- 4.7) had significantly higher VEFR for both sides: 18.9 +/- 6.7% versus 11.2 +/- 6.7%, p VEP and VEFR amplitudes were well correlated. However, this was significant only for younger subjects and more evident in D side. The CI was higher in young subjects compared to those in old ones (6.49 +/- 2.79 versus 4.75 +/- 2.35, respectively, p = 0.007). But, this age-related trend remained as borderline when sides were analyzed individually: In the young subjects CI was 5.99 +/- 2.21 and 6.96 +/- 3.22 for D and ND sides, while those were 4.27 +/- 2.60 and 5.19 +/- 2.07 in old ones. This study confirmed diminished visual evoked flow in relation with advancing age, and suggested that "weakened" neurovascular coupling (as evidenced by a decreased VEP and VEFR correlation along with decreased CI) as one of the underlying mechanisms.

  13. NLP-12 engages different UNC-13 proteins to potentiate tonic and evoked release. (United States)

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


    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.

  14. Multimodality evoked potentials in patients with delayed encephalopathy after acute carbon monoxide poisoning

    Institute of Scientific and Technical Information of China (English)

    Xiahong Wang; Bo Xiao; Renjun Gu; Lan Xiao; Yi Yang; Yinhui Hao; Nini Wang; Junlin Mu; Jinggang Yin


    Objective: To evaluate the diagnostic and prognostic values in patients with delayed encephalopathy after acute carbon monoxide poisoning. Methods: The tibial nerve somatosensory evoked potentials (SEPs), vision evoked potentials (VEPs), and brain stem audition evoked potentials(BAEPs) were performed in 32 healthy adults and 43 patients with delayed encephalopathy after acute carbon monoxide poisoning. Results: This paper indicated abnormalities of tibial nerve SEPs in 31 patients (31/43, 72.1%), VEPs in 17 patients (17/28, 60.7%), and BAEPs in 14 patients (14/43, 32.6%). These results showed that the greatest diagnostic value was SEPs, followed by VEPs and, BAEPs with the lowest sensitivity. Conclusion: Multimodality evoked potentials (EPs) can be used for evaluating the diagnostic and prognostic values in cases of delayed encephalopathy after acute carbon monoxide poisoning.

  15. Magnetic stimulation of muscle evokes cerebral potentials in assessment of paraspinal muscle spasm.

    Institute of Scientific and Technical Information of China (English)


    Objectlve: To assess the muscle spasm by magnetic stimulation of muscle evokes cerebral potentials (MMSEP). Methods: Paraspinal MMSEP and function assessment was recorded in detail before and after treat-

  16. Quantifying interhemispheric symmetry of somatosensory evoked potentials with the intraclass correlation coefficient

    NARCIS (Netherlands)

    van de Wassenberg, Wilma J. G.; van der Hoeven, Johannes H.; Leenders, Klaus L.; Maurits, Natasha M.

    Although large intersubject variability is reported for cortical somatosensory evoked potentials (SEPs), variability between hemispheres within one subject is thought to be small. Therefore, interhemispheric comparison of SEP waveforms might be clinically useful to detect unilateral abnormalities in

  17. Quantifying interhemispheric symmetry of somatosensory evoked potentials with the intraclass correlation coefficient

    NARCIS (Netherlands)

    van de Wassenberg, Wilma J. G.; van der Hoeven, Johannes H.; Leenders, Klaus L.; Maurits, Natasha M.


    Although large intersubject variability is reported for cortical somatosensory evoked potentials (SEPs), variability between hemispheres within one subject is thought to be small. Therefore, interhemispheric comparison of SEP waveforms might be clinically useful to detect unilateral abnormalities in

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

    Institute of Scientific and Technical Information of China (English)


    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.

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

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


    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

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

    Directory of Open Access Journals (Sweden)

    Pritish J Korula


    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

  1. [Effects of nicotine on visually evoked EEG potentials]. (United States)

    Woodson, P P; Bättig, K; Rosecrans, J A


    The effects of nicotine were measured on the averaged visual evoked response (AVER) through the use of two types of experimental cigarettes which differed only in nicotine content (i.e., 0.14 vs. 1.34 mg/cig.). The results indicate that the restorative and/or enhancing effects of cigarette smoking on peak amplitudes are due predominantly to nicotine's psychopharmacologic effects, and support past research indicating that nicotine may enhance visual attentional processes in the quiescent smoker. This contrasts with other reports indicating nicotine to have a depressant effect on auditory processes.

  2. Determination of evoked potentials in occupational and environmental medicine: a review. (United States)

    Araki, S; Murata, K


    The measurement of cerebral evoked and event-related potentials is a promising technique for assessment of subclinical neurotoxicity and has recently been introduced into occupational and environmental medicine. Evoked potentials consist of somatosensory, visual, and auditory evoked potentials, and event-related potentials include the P300 potential. Measurement of these potentials can localize central nervous system impairments caused by exposure to a wide variety of hazardous factors in the workplace and the general environment. This paper is intended to provide an overview of research utilizing these potentials to evaluate the effects of work-related factors. The available data indicate that these potentials are sensitive and reliable methods that are easily standardized and practical to apply in the field setting. Researchers should note, however, that several covariates such as age, skin or body temperature, height, alcohol ingestion, and intelligence can influence assessment of these cerebral potentials in clinical and epidemiologic studies.

  3. Diminished N1 auditory evoked potentials to oddball stimuli in misophonia patients

    Directory of Open Access Journals (Sweden)

    Arjan eSchröder


    Full Text Available Misophonia (hatred of sound is a newly defined psychiatric condition in which ordinary human sounds, such as breathing and eating, trigger impulsive aggression. In the current study we investigated if a dysfunction in the brain’s early auditory processing system could be present in misophonia. We screened 20 patients with misophonia with the diagnostic criteria for misophonia, and 14 matched healthy controls without misophonia, and investigated any potential deficits in auditory processing of misophonia patients using auditory event-related potentials (ERPs during an oddball task.Subjects watched a neutral silent movie while being presented a regular frequency of beep sounds in which oddball tones of 250 Hz and 4000 Hz were randomly embedded in a stream of repeated 1000 Hz standard tones. We examined the P1, N1 and P2 components locked to the onset of the tones.For misophonia patients, the N1 peak evoked by the oddball tones had a smaller mean peak amplitude than the control group. However, no significant differences were found in P1 and P2 components evoked by the oddball tones. There were no significant differences between the misophonia patients and their controls in any of the ERP components to the standard tones.The diminished N1 component to oddball tones in misophonia patients suggests an underlying neurobiological deficit in misophonia patients. This reduction might reflect a basic impairment in auditory processing in misophonia patients.

  4. Neuromodulation of evoked muscle potentials induced by epidural spinal-cord stimulation in paralyzed individuals. (United States)

    Sayenko, Dimitry G; Angeli, Claudia; Harkema, Susan J; Edgerton, V Reggie; Gerasimenko, Yury P


    Epidural stimulation (ES) of the lumbosacral spinal cord has been used to facilitate standing and voluntary movement after clinically motor-complete spinal-cord injury. It seems of importance to examine how the epidurally evoked potentials are modulated in the spinal circuitry and projected to various motor pools. We hypothesized that chronically implanted electrode arrays over the lumbosacral spinal cord can be used to assess functionally spinal circuitry linked to specific motor pools. The purpose of this study was to investigate the functional and topographic organization of compound evoked potentials induced by the stimulation. Three individuals with complete motor paralysis of the lower limbs participated in the study. The evoked potentials to epidural spinal stimulation were investigated after surgery in a supine position and in one participant, during both supine and standing, with body weight load of 60%. The stimulation was delivered with intensity from 0.5 to 10 V at a frequency of 2 Hz. Recruitment curves of evoked potentials in knee and ankle muscles were collected at three localized and two wide-field stimulation configurations. Epidural electrical stimulation of rostral and caudal areas of lumbar spinal cord resulted in a selective topographical recruitment of proximal and distal leg muscles, as revealed by both magnitude and thresholds of the evoked potentials. ES activated both afferent and efferent pathways. The components of neural pathways that can mediate motor-evoked potentials were highly dependent on the stimulation parameters and sensory conditions, suggesting a weight-bearing-induced reorganization of the spinal circuitries.

  5. Cortico-cortical evoked potentials for sites of early versus late seizure spread in stereoelectroencephalography. (United States)

    Lega, Bradley; Dionisio, Sasha; Flanigan, Patrick; Bingaman, William; Najm, Imad; Nair, Dileep; Gonzalez-Martinez, Jorge


    Cortico-cortical evoked potentials offer the possibility of understanding connectivity within seizure networks to improve diagnosis and more accurately identify candidates for seizure surgery. We sought to determine if cortico-cortical evoked potentials and post-stimulation oscillatory changes differ for sites of EARLY versus LATE ictal spread. 37 patients undergoing stereoelectroencephalography were tested using a cortico-cortical evoked potential paradigm. All electrodes were classified according to the speed of ictal spread. EARLY spread sites were matched to a LATE spread site equidistant from the onset zone. Root-mean-square was used to quantify evoked responses and post-stimulation gamma band power and coherence were extracted and compared. Sites of EARLY spread exhibited significantly greater evoked responses after stimulation across all patients (t(36)=2.973, p=0.004). Stimulation elicited enhanced gamma band activity at EARLY spread sites (t(36)=2.61, p=0.03, FDR corrected); this gamma band oscillation was highly coherent with the onset zone. Cortico-cortical evoked potentials and post-stimulation changes in gamma band activity differ between sites of EARLY versus LATE ictal spread. The oscillatory changes can help visualize connectivity within the seizure network.

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

    Directory of Open Access Journals (Sweden)

    Robert eKromer


    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.

  7. Monitoring somatosensory evoked potentials in spinal cord ischemia-reperfusion injury

    Institute of Scientific and Technical Information of China (English)

    Yiming Ji; Bin Meng; Chenxi Yuan; Huilin Yang; Jun Zou


    It remains unclear whether spinal cord ischemia-reperfusion injury caused by ischemia and other non-mechanical factors can be monitored by somatosensory evoked potentials. Therefore, we monitored spinal cord ischemia-reperfusion injury in rabbits using somatosensory evoked potential detection technology. The results showed that the somatosensory evoked potential latency was significantly prolonged and the amplitude significantly reduced until it disappeared during the period of spinal cord ischemia. After reperfusion for 30-180 minutes, the amplitude and latency began to gradual y recover; at 360 minutes of reperfusion, the latency showed no significant difference compared with the pre-ischemic value, while the somatosensory evoked potential amplitude in-creased, and severe hindlimb motor dysfunctions were detected. Experimental findings suggest that changes in somatosensory evoked potential latency can reflect the degree of spinal cord ischemic injury, while the amplitude variations are indicators of the late spinal cord reperfusion injury, which provide evidence for the assessment of limb motor function and avoid iatrogenic spinal cord injury.


    Institute of Scientific and Technical Information of China (English)


    Objective To study direct cortical electrical stimulation technique for the recording of motor evoked potentials under general anesthesia in central sulcus lesions. Methods The largest N20-P25 response was recorded from postcentral gyrus by intraoperative monitoring of cortical motor evoked potentials in 10 patients with intracranial lesions near or in the central area. The muscles of upper extremity in all patients were activated by delivering stimulus to cortical areas continuously. Moving the cortical electrodes forward, the largest P20-N25 response, SEP phase reversal,was obtained as a motor center stimulus. In this site of cortex, a short train stimulation elicited reproducible muscle action potentials that could be observed from the oscilloscope without averaging.Results MEPs can be recorded, pre- and post-operatively, without motor deficits of upper limbs in all patients.Conclusion This technique seems to be preferable for intraoperative localization of motor evoked potentials in central sulcus lesions under total intravenous anesthesia.

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

    DEFF Research Database (Denmark)

    Iodice, R; Carotenuto, A; Dubbioso, R


    BACKGROUND: Clinical trials have shown the therapeutic effect of fingolimod in reducing disease activity in relapsing-remitting multiple sclerosis (RR-MS), but its influence on nervous conduction assessed by evoked potentials (EPs) has not been previously investigated. METHODS: EP data of 20...... 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...... 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...

  10. Multifocal visual evoked potential latency analysis: predicting progression to multiple sclerosis. (United States)

    Fraser, Clare; Klistorner, Alexander; Graham, Stuart; Garrick, Raymond; Billson, Francis; Grigg, John


    To monitor the difference in conversion rates to multiple sclerosis (MS) in 46 patients with optic neuritis between patients with multifocal visual evoked potential latency delay and those with normal latency. Prospective case series. Metropolitan neuro-ophthalmology clinic. Forty-six patients with optic neuritis who did not have a diagnosis of MS on enrollment in the study. Conversion to MS according to the McDonald criteria. Analysis revealed that only 22 subjects had multifocal visual evoked potential latency delay. Over 1 year, 36.4% of patients with optic neuritis with latency delays progressed clinically to MS compared with 0% of those with normal latencies (P = .03, chi2). This may indicate that multifocal visual evoked potential latency delay can assist in predicting progression to future MS.

  11. Quantifying the effect of isoflurane and nitrous oxide on somatosensory-evoked potentials

    Directory of Open Access Journals (Sweden)

    Usha Devadoss


    Full Text Available Anaesthetic techniques may have a significant effect on intraoperative-evoked potentials (EP. The present study is designed to compare Propofol anaesthesia with Isoflurane (with or without nitrous oxide during intraoperative somatosensory-evoked potential (SSEP monitoring in 15 ASA Grade I and II patients undergoing surgery for intracranial tumours. SSEPs in response to median and posterior tibial nerve stimulation were recorded under four different anaesthetic conditions: 1 Propofol infusion and ventilation with air-oxygen, 2 Isoflurane, 1.0 MAC and ventilation with air-oxygen, 3 Isoflurane 1.0 MAC and ventilation with nitrous oxide-oxygen, and 4 Return to Isoflurane, 1.0 MAC and ventilation with air-oxygen. Intraoperative monitoring of somatosensory evoked potentials is best recordable using Propofol. The morphology of the EP is reproducible with Isoflurane. This effect is exaggerated when it is advisable to avoid nitrous oxide.

  12. Dynamic extraction of visual evoked potentials through spatial analysis and dipole localization. (United States)

    Wang, Y; Yang, F


    The dynamic extraction of evoked potential is a problem of great interest in EEG signal processing. In this paper, a comprehensive method is presented which integrates spatial analysis and dipole localization to make full use of the spatial-temporal information contained in the multichannel stimulation records. A realistic double boundary head model is constructed through CT scans and a two-step method devised to overcome the ill-posed nature of the forward problem of EEG caused by the low conductivity of the skull. As a result, visual evoked potentials can be effectively extracted from only two consecutive records and the dynamic information of visual evoked potential thus procured. The efficiency of the presented method has been verified by means of computer simulation and a clinical experiment.

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

    DEFF Research Database (Denmark)

    Malmqvist, Lasse; De Santiago, L; Fraser, C


    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 purpose...

  14. Visual evoked potentials monitoring in a case of transient post-operative visual loss

    Directory of Open Access Journals (Sweden)

    Marie Capon


    Full Text Available Post-operative visual loss (POVL is a rare, albeit potentially serious complication of general anaesthesia. This report describes the case of a 54-year-old woman who developed transient POVL after general anaesthesia following a left posterior parietal meningioma surgery in the prone position and discusses the usefulness of visual evoked potentials monitoring in such situations.

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

    Directory of Open Access Journals (Sweden)

    Senthil Kumar Subramanian


    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.

  16. Brownian Optogenetic-Noise-Photostimulation on the Brain Amplifies Somatosensory-Evoked Field Potentials. (United States)

    Huidobro, Nayeli; Mendez-Fernandez, Abraham; Mendez-Balbuena, Ignacio; Gutierrez, Ranier; Kristeva, Rumyana; Manjarrez, Elias


    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.

  17. Refractory episodic vertigo: role of intratympanic gentamicin and vestibular evoked myogenic potentials. (United States)

    Celis-Aguilar, Erika; Hinojosa-González, Ramon; Vales-Hidalgo, Olivia; Coutinho-Toledo, Heloisa

    Even today, the treatment of intractable vertigo remains a challenge. Vestibular ablation with intratympanic gentamicin stands as a good alternative in the management of refractory vertigo patients. To control intractable vertigo through complete saccular and horizontal canal vestibular ablation with intratympanic gentamicin treatment. Patients with refractory episodic vertigo were included. The inclusion criteria were: unilateral ear disease, moderate to profound sensorineural hearing loss, and failure to other treatments. Included patients underwent 0.5-0.8mL of gentamicin intratympanic application at a 30mg/mL concentration. Vestibular ablation was confirmed by the absence of response on cervical vestibular evoked myogenic potentials and no response on caloric tests. Audiometry, electronystagmography with iced water, and vestibular evoked myogenic potentials were performed in all patients. Ten patients were included; nine patients with Meniere's disease and one patient with (late onset) delayed hydrops. Nine patients showed an absent response on vestibular evoked myogenic potentials and no response on caloric tests. The only patient with low amplitude on cervical vestibular evoked myogenic potentials had vertigo recurrence. Vertigo control was achieved in 90% of the patients. One patient developed hearing loss >30dB. Cervical vestibular evoked myogenic potentials confirmed vestibular ablation in patients treated with intratympanic gentamicin. High-grade vertigo control was due to complete saccular and horizontal canal ablation (no response to iced water in electronystagmography and no response on cervical vestibular evoked myogenic potentials). Copyright © 2016 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

  18. Effects of single cycle binaural beat duration on auditory evoked potentials. (United States)

    Mihajloski, Todor; Bohorquez, Jorge; Özdamar, Özcan


    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.

  19. Properties of rectified averaging of an evoked-type signal: theory and application to the vestibular-evoked myogenic potential. (United States)

    Colebatch, J G


    The properties of rectified averages were investigated using the VEMP (vestibular-evoked myogenic potential) as an example of an evoked-type response. Recordings were made of surface EMG from the sternocleidomastoid (SCM) muscles of six volunteers, unstimulated, at different levels of tonic activation and then in response to clicks of different intensities. The stochastic properties of the surface EMG recorded were shown to be well modelled using a zero mean normal distribution with a standard deviation equivalent to the mean RMS (root mean squared) value (mean residual error variance 0.87%). Assuming a normal distribution, equations were derived for the expected value of both the rectified and RMS average with the addition of constant waveforms of different sizes. A simulation using recorded EMG and added sine waves of different amplitudes demonstrated that the equations predicted the rectified averages accurately. It also confirmed the importance of the relative amplitude of the added signal in determining whether it was detected using rectified averages. The same equations were then applied to actual data consisting of VEMPs of different relative amplitudes recorded from the volunteers. Whilst the signal-to-noise ratio (measured by corrected amplitude) was a major determinant of the nature of the rectified average, consistent deviations were detected between the predicted and actual rectified averages. Deviations from predicted values indicated that the VEMP did not behave simply like a constant signal added to tonic background EMG. A more complicated model, which included temporal jitter as well as inhibition of background EMG during the VEMP, was required to fit the physiological recordings. Rectified averages are sensitive to physiological properties, which are not apparent when using unrectified averages alone. Awareness of the properties of rectified averages should improve their interpretation.

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

    DEFF Research Database (Denmark)

    Arnfred, S; He, Chen; Eder, D


    We studied cerebral evoked potentials on the scalp to the stimulation of the right hand from a change in weight of 400-480 g in ten subjects. Rise-time was 20g/10 ms, Inter Stimulus Interval 2s and stimulus duration was 100 ms. The cerebral activations were a double positive contralateral C3'/P70......, 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...

  1. 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

    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...... showed reproducibility with ICCs for all bands >0.8 and corresponding CVs potentials evoked from the anal canal are challenged by latency jitter likely related to variability in muscle tone due to the distensions. Using single-sweep analysis, anal CEPs proved...


    Institute of Scientific and Technical Information of China (English)

    管宇宙; 崔丽英; 汤晓芙; 李本红; 杜华


    Objective. To study the features and mechanism of the cerebral evoked potentials by repetitive stimulation of calf muscle in Duchenne muscular dystrophy (DMD) patients with obvious muscular dystrophy and psuedohypertrophy. Methods. Cerebral evoked potentials by stimulation of calf muscles and somatusensory evoked potentials(SEPs) by the stimulation of posterior tibial nerves at ankle were measured in 10 patients with DMD and 10 norreal controls matched with gender and age. The intensity of the magnetic stimulation was at 30% of maximal output (2. 1 Tesla, MagPro magnetic stimulator, Dantec) and the frequency was 1 Hz. The low intensity of magnet-ic stimulation was just sufficient to produce a contraction of the muscle belly underneath the coil. Recording electrode was placed at 2 cm posterior to the Cz, reference to Fpz. The latencies of N33, P38, N48 and P55 and ampli-tude (P38 - N48) were recorded. SEPs were recorded by routine methods. Results. In normal subjects, the amphtudes of cerebral evoked potentials by magnetic stimulation of calf mus-cle was 40% lower than that by electrical stimulation of the posterior tibial nerves at ankle. The latency of P38 was 2. 9 ± 2. 1 ms longer compared with electrical stimulation of the posterior tibial nerves at ankle. In 6 patients, P38 latency from magnetic stimulation was remarkably prolonged ( P < 0. 01), and in 4 patients, there was no remarkable response. SEPs evoked by electrical stimulation were normal in all of the patients. Conclusion. DMD is an available model for the study of mechanism of cerebral evoked potentials by magnetic stimulating muscle. We can conclude that the responses from magnetic stimulation were produced by muscle input. The abnormal responses in patients may relate to decreased input of muscle by stimulating dystrophic and psedohypertrophic muscle.

  3. [Mechanism of the generation of evoked potentials in the rabbit neocortex]. (United States)

    Pockberger, H; Rappelsberger, P


    This paper describes the analyses of evoked potentials recorded in different neocortical areas (Area precentralis 1 and 2, occipitalis 1 and 2) and elicited by different stimulation techniques (antidromic stimulation of the pyramidal tract, electrical stimulation of thalamic nuclei, the optic nerve and finally random dot stimulation of the retina). Field potentials were recorded intracortically with a 16-fold electrode. The analyses of field potentials with the current-source-density method yielded an estimation of the current source and sink density distributions within the six neocortical layers. Hence spatio-temporal patterns of layer specific activation processes (sinks and sources) can be described for the various evoked potentials. The results can be summarized as follows: every evoked potential shows a spatio-temporal pattern of sources and sinks which is independent of the neocortical area and the mode of stimulation. However, the late components of the evoked potentials show great variations in their generation mechanisms, thus indicating regional differences in neocortical architectonics. These observations are discussed with regard to morphology, electrical activity and functional properties of the studied neocortical areas.

  4. Potential application of ocular and cervical vestibular-evoked myogenic potentials in Meniere's disease: a review. (United States)

    Young, Yi-Ho


    By stimulating the ear with air-conducted sound or bone-conducted vibration stimuli, vestibular-evoked myogenic potential (VEMP) can be recorded on the contracted neck muscles, termed cervical VEMP (cVEMP), and on the extraocular muscles, termed ocular VEMP (oVEMP). These two electrophysiological tests expand the test battery for clinicians to explore the dynamic otolithic function, adding a potential usefulness to the sacculocollic reflex and vestibulo-ocular reflex, respectively. The inner ear test battery, including audiometry, and cVEMP, oVEMP and caloric tests, is designed for complete evaluation of the inner ear function, namely, the cochlea, saccule, utricle, and semicircular canals, respectively. Using this test battery to study the localization and prevalence of hydrops formation reveals that the declining function in the cochlea, saccule, utricle, and semicircular canals mimics the declining sequence of hydrops formation in temporal bone studies. This study reviewed the physiological results in Meniere's patients via the inner ear test battery, especially the potential application of the oVEMP and cVEMP tests, to correlate with the histopathological findings of Meniere's disease. Copyright © 2012 The American Laryngological, Rhinological, and Otological Society, Inc.

  5. Diagnostic accuracy of evoked potentials for functional impairment after contusive spinal cord injury in adult rats. (United States)

    Thirumala, Parthasarathy; Zhou, James; Krishnan, Rohan; Manem, Nihita; Umredkar, Shreya; Hamilton, D K; Balzer, Jeffrey R; Oudega, Martin


    Iatrogenic spinal cord injury (SCI) is a cause of potentially debilitating post-operative neurologic complications. Currently, intra-operative neurophysiological monitoring (IONM) via somatosensory evoked potentials and motor-evoked potentials is used to detect and prevent impending SCI. However, no empirically validated interventions exist to halt the progression of iatrogenic SCI once it is detected. This is in part due to the lack of a suitable translational model that mimics the circumstances surrounding iatrogenic SCI detected via IONM. Here, we evaluate a model of simulated contusive iatrogenic SCI detected via IONM in adult female Sprague-Dawley rats. We show that transient losses of somatosensory evoked potentials responses are 88.24% sensitive (95% confidence interval [CI] 63.53-98.20) and 80% specific (95% CI 51.91-95.43) for significant functional impairment following simulated iatrogenic SCI. Similarly, we show that transient losses in motor-evoked potentials responses are 70.83% sensitive (95% CI 48.91-87.33) and 100% specific (95% CI 62.91-100.00) for significant functional impairment following simulated iatrogenic SCI. These results indicate that our model is a suitable replica of the circumstances surrounding clinical iatrogenic SCI.

  6. Absence of both auditory evoked potentials and auditory percepts dependent on timing cues. (United States)

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


    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.

  7. The mechanisms underlying long-term potentiation of C-fiber evoked field potentials in spinal dorsal horn

    Institute of Scientific and Technical Information of China (English)

    LIU Xian-Guo


    Long-term potentiation (LTP) of C-fiber evoked feld potentials in spinal dorsal horn is first reported in 1995. Since then, the mechanisms underlying the long-lasting enhancement in synaptic transmission between primary afferent C-fibers and neurons in spinal dorsal horn have been investigated by different laboratories. In this article, the related data were summarized and discussed.

  8. Vestibular-evoked myogenic potentials in miniature pigs

    Directory of Open Access Journals (Sweden)

    Xi Shi


    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.

  9. The effect of alcohol on cervical and ocular vestibular evoked myogenic potentials in healthy volunteers


    Rosengren, S M; Weber, K P; Hegemann, S C A; Roth, T N


    OBJECTIVE: We investigated the effect of alcohol on the cervical and ocular vestibular evoked myogenic potentials (cVEMPs and oVEMPs). As alcohol produces gaze-evoked nystagmus (GEN), we also tested the effect of nystagmus independent of alcohol by recording oVEMPs during optokinetic stimulation (OKS). METHODS: The effect of alcohol was tested in 14 subjects over multiple rounds of alcohol consumption up to a maximum breath alcohol concentration (BrAC) of 1.5‰ (mean 0.97‰). The effect of O...

  10. Attentional Modulation of Visual-Evoked Potentials by Threat: Investigating the Effect of Evolutionary Relevance (United States)

    Brown, Christopher; El-Deredy, Wael; Blanchette, Isabelle


    In dot-probe tasks, threatening cues facilitate attention to targets and enhance the amplitude of the target P1 peak of the visual-evoked potential. While theories have suggested that evolutionarily relevant threats should obtain preferential neural processing, this has not been examined empirically. In this study we examined the effects of…

  11. 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...

  12. A Steady State Visually Evoked Potential Investigation of Memory and Ageing (United States)

    Macpherson, Helen; Pipingas, Andrew; Silberstein, Richard


    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…

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

    DEFF Research Database (Denmark)

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


    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...

  14. Cervical vestibular evoked myogenic potentials and caloric test results in individuals with auditory neuropathy spectrum disorders. (United States)

    Sujeet, Kumar Sinha; Niraj, Kumar Singh; Animesh, Barman; Rajeshwari, G; Sharanya, R


    Auditory neuropathy spectrum disorder is a type of hearing loss where outer hair cell function are normal (as evidenced by the preservation of OAEs and cochlear microphonics), whereas auditory nerve functions are abnormal (as evidenced by abnormal auditory brainstem evoked potentials beginning with wave I of the ABR) and acoustic reflexes to ipsilateral and contralateral tones are absent. It is likely that in cases with auditory neuropathy spectrum disorder not only the cochlear nerve, but also the vestibular nerves might get involved. The present study was conducted with an aim of finding out the inferior and superior vestibular nerve involvement through cervical vestibular evoked myogenic potentials and Caloric test results respectively in individuals with Auditory Neuropathy Spectrum Disorders. Total 26 participants who fulfilled the criteria of auditory neuropathy spectrum disorder participated for the study. Vestibular evoked myogenic potentials results showed absence of responses from most of the subjects also caloric responses showed bilateral hypofunctional responses in most of the participants, which is suggestive of involvement of both the inferior as well as superior vestibular nerve in individuals with auditory neuropathy spectrum disorders. Additionally there was no association between the pattern and degree of hearing loss to caloric test results and vestibular evoked myogenic potentials results findings.

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

    DEFF Research Database (Denmark)

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


    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...

  16. Visual, auditory, and somatosensorial evoked potentials in early and late treated adolescents with phenylketonuria. (United States)

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


    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.

  17. 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


    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...

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

    DEFF Research Database (Denmark)

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


    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...

  19. Electrically Elicited Visual Evoked Potentials in Argus II Retinal Implant Wearers



    We characterized electrically elicited visual evoked potentials (eVEPs) in Argus II retinal implant wearers. eVEPs were correlated significantly with stimulus level and subjective percept. We conclude that eVEPs may become an important tool for intraoperative monitoring and rehabilitation purposes.


    Institute of Scientific and Technical Information of China (English)

    肖泽萍; 陈兴时; 张明岛; 楼翡璎; 陈珏


    Objective To investigate the status of evoked potentials in obsessive-compulsive disorder (OCD). Methods Evoked potentials P300 , auditory brainstem response ( ABR ) and visual evoked potential (VEP) were recorded from 35 OCD patients and 28 normal controls (NC) with a Nicolet Spirit Instrument. 23 of the OCD patients were followed up after 5 months with the same markers. Results Compared with NC, OCD patients showed decreased P3 of P300 amplitude ( OCD group 3.5 + 1.6μv vs. NC group 5.9 +2.1 μv, P <0.01 ),delayed V latency (6.4 +0. 4ms vs. 5.5 +0.3ms, P <0.01 ) and increased V amplitude( 0.35 ±0.1μv vs. 0.16 ±0.09μv, P <0.05)of ABR and delayed P2 of VEP latency (199 ±39ms vs. 183 +28ms, P <0. 05). The followup measures of evoked potentials suggested that decreased P3 of P300 amplitude and delayed P2 of VEP latency might be state markers of OCD , while decreased V amplitude and delayed V of ABR latency might be trait markers of OCD. Conclusion The changes of P300 and VEP are related to clinical status of OCD patients, while the association between ABR and OCD symptoms need to be further investigated.

  1. 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 an

  2. 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 c

  3. Effects of Form Perception and Meaning on the Visual Evoked Potential with Author’s Update (United States)


    interpretations of reversible figures, simple geometrical forms, and consonant- vowel -consonant (cvc) trigrams with differently ordered consonants were...employed. Why, then, look at visual evoked potentials resulting from ambiguous figures and consonant- vowel -consonant (cvc) trigrams? When I was...ability to investigate the brain mechanisms for processing information, attention, perception, emotion , and consciousness, the hardware did not tell what



    Swathi; Sathish Kumar


    ABSTRACT : Auditory system is shaped by experience and training. Training (s ensory experience) induces neurophysiologic changes & plasticity in normal hearing individuals, hearing loss patients, hearing aid users and cochlear implanted subjects. Not only speech stimulus, but music also brings about functional and structural organi zation of the brain in musician compared to non - musicians. The Vestibular evoked myogenic potentials (VEMP) are a biphasic in...

  5. 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


    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...

  6. Nociception-related somatosensory evoked potentials in awake dogs recorded after intra epidermal electrical stimulation

    NARCIS (Netherlands)

    van Oostrom, H.; Stienen, P.J.; Doornenbal, A.; Hellebrekers, L.J.


    Eur J Pain. 2009 Feb;13(2):154-60. Epub 2008 May 16. Nociception-related somatosensory evoked potentials in awake dogs recorded after intra epidermal electrical stimulation. van Oostrom H, Stienen PJ, Doornenbal A, Hellebrekers LJ. Department of Clinical Sciences of Companion Animals, Division Anest

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

    Directory of Open Access Journals (Sweden)

    Lu Li


    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.

  8. [Intraoperative monitoring: visual evoked potentials in surgery of the sellar region]. (United States)

    Lorenz, M; Renella, R R


    During 18 sellar and perisellar operations the optic tract was monitored by visual evoked potentials (VEP). Deteriorations of the cortical responses were recorded in 73%. In this patients there was no close correlation between the intraoperative findings and the postoperative visual function. Only in those patients who showed no remarkable intraoperative changes VEP seemed to be of reliable prognostic value.

  9. Negative Component of Visual Evoked Potential in Children with Cognitive Processing. (United States)

    Yanagihara, Masafumi; Sako, Akihito

    This study investigates a negative component (N220) of visual evoked potential (VEP) which increases as certain cognitive processes are activated. Nine experimental conditions were designed by combining three stimulus and three task conditions. Letters were used as verbal stimuli, matrix patterns were used as nonverbal stimuli, and white light was…

  10. The analysis of multiple habituation profiles of single trial evoked potentials

    NARCIS (Netherlands)

    Molenaar, P.C.M.; Roelofs, J.W.


    Presents a new statistical technique for analyzing multiple habituation profiles of single-trial evoked potentials (EPs). The method is based on a model of the essential characteristics of the habituation process--trial-dependent modulation of amplitude and phase of the underlying brain responses to

  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.


    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...

  12. Feasibility and performance evaluation of generating and recording visual evoked potentials using ambulatory Bluetooth based system. (United States)

    Ellingson, Roger M; Oken, Barry


    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.

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

    Directory of Open Access Journals (Sweden)

    Lee Tien-Wen


    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.

  14. Auditory evoked potential P300 in adults: reference values. (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


    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.

  15. Multifocal Visual Evoked Potential (mfVEP) and Pattern-Reversal Visual Evoked Potential Changes in Patients with Visual Pathway Disorders: A Case Series. (United States)

    Alshowaeir, Daniah; Yiannikas, Con; Klistorner, Alexander


    The purpose of this study was to evaluate multifocal visual evoked potential (mfVEP) and pattern-reversal visual evoked potential (PVEP) changes in patients with pathology at various levels of the visual pathway determined by other methods. Six patients with different visual pathway disorders, including vascular ischaemic events and compressive optic neuropathy, were reviewed. All patients were tested with both mfVEP and full-field and half-field PVEPs. Results were assessed in relation to other diagnostic tests such as magnetic resonance imaging, Humphrey visual field test, and optical coherence topography. The cases in this study demonstrate a potential higher sensitivity of mfVEP compared with conventional PVEPs in detecting lesions affecting the peripheral field, horizontal hemifields, and lesions of the post-chiasmal pathway. The limitation of the PVEP in this setting is probably due to phase cancellation and overrepresentation of the macular region. mfVEP provides a more accurate assessment of visual defects when compared with conventional PVEP. The independent assessment of different areas of the visual field improves the detection and localization of lesions and provides an objective topographical map that can be used in clinical practice as an adjunct to other diagnostic tests and to assess disease progression.

  16. Noninvasive scalp recording of cortical auditory evoked potentials in the alert macaque monkey. (United States)

    Itoh, Kosuke; Nejime, Masafumi; Konoike, Naho; Nakada, Tsutomu; Nakamura, Katsuki


    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.

  17. Disturbances of stem circumnutations evoked by wound-induced variation potentials in Helianthus annuus L. (United States)

    Stolarz, Maria; Dziubińska, Halina; Krupa, Maciej; Buda, Agnieszka; Trebacz, Kazimierz; Zawadzki, Tadeusz


    The relationship between evoked electrical activity and stem movements in three-week old sunflowers was demonstrated. Electrical potential changes (recorded by Ag/AgCl extracellular electrodes) and time-lapse images (from a top view camera) were recorded and analyzed. A heat stimulus applied to the tip of one of the second pair of leaves evoked a variation potential, transmitted basipetally along one side of the stem. After stimulation, disturbances of circumnutations occurred. They included: changes in the period, disorders in the elliptical shape, and, in some cases, reversion of direction (of movement). We suggest that asymmetrically propagated variation potential induces asymmetric stem shrinking and bending, which strongly disturbs circumnutations. Our results confirm the involvement of electrical potential changes in the mechanism of stem nutations.

  18. Role of motor evoked potentials in diagnosis of cauda equina and lumbosacral cord lesions. (United States)

    Di Lazzaro, V; Pilato, F; Oliviero, A; Saturno, E; Dileone, M; Tonali, P A


    To determine the diagnostic value of motor evoked potentials (MEPs) in the diagnosis of lumbosacral cord disorders. MEPs in 37 patients with sensory and motor deficits in the lower limbs were studied. MRI demonstrated spinal cord involvement in 10 patients and cauda equina lesions in 27 patients. A double determination of central motor conduction time (CMCT), calculated as the difference between the latencies of responses evoked by cortical and paravertebral magnetic stimulation and as the difference between the latency of cortical MEP and the total peripheral conduction time calculated from the F-wave latency, enabled discrimination between a delay along the proximal root and a delay along the corticospinal tract. An abnormality of the CMCT calculated with both techniques is indicative of central motor pathway damage, whereas an abnormality of the CMCT calculated from the latency of responses evoked by paravertebral magnetic stimulation associated with a normal CMCT calculated from the F-wave latency suggests a cauda equina lesion. Neurophysiologic findings strongly correlated with the lesion site documented by MRI (cauda equina or lumbosacral cord). All patients with MR evidence of cord involvement had an abnormality of CMCT calculated with both methods, suggesting a lesion of central motor pathways. Clinical examination often failed to document a spinal cord lesion, suggesting pure peripheral involvement in 5 of the 10 patients with MR evidence of cord lesion. Motor evoked potential recording is an accurate and easily applicable test for the diagnosis of lumbosacral spinal cord lesions.

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

    Directory of Open Access Journals (Sweden)

    Masoud Motasaddi Zarandy


    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.

  20. The Single Training Sample Extraction of Visual Evoked Potentials Based on Wavelet Transform

    Institute of Scientific and Technical Information of China (English)

    LIU Fang; ZHANG Zhen; CHEN Wen-chao; QIN Bing


    Abstract.Based on the good localization characteristic of the wavelet transform both in time and frequency domain, a de-noising method based on wavelet transform is presented, which can make the extraction of visual evoked potentials in single training sample from the EEG background noise in favor of studying the changes between the single sample response happen. The information is probably related with the different function, appearance and pathologies of the brain. At the same time this method can also be used to remove those signal' s artifacts that do not appear with EP within the same scope of time or frequency. The traditional Fourier filter can hardly attain the similar result. This method is different from other wavelet de-noising methods in which different criteria are employed in choosing wavelet coefficient. It has a biggest virtue of noting the differences among the single training sample and making use of the characteristics of high time frequency resolution to reduce the effect of interference factors to a maximum extent within the time scope that EP appear. The experiment result proves that this method is not restricted by the signal-tonoise ratio of evoked potential and electroencephalograph (EEG) and even can recognize instantaneous event under the condition of lower signal-to-noise ratio, as well as recognize the samples which evoked evident response more easily. Therefore, more evident average evoked response could be achieved by de-nosing the signals obtained through averaging out the samples that can evoke evident responses than de-nosing the average of original signals. In addition, averaging methodology can dramatically reduce the number of record samples needed, thus avoiding the effect of behavior change during the recording process.This methodology pays attention to the differences among single training sample and also accomplishes the extraction of visual evoked potentials from single trainings sample. As a result, system speed and


    Institute of Scientific and Technical Information of China (English)

    贲晓明; 秦玉明; 吴圣楣; 张惠民; 陈舜年; 夏振炜


    Objective Evaluate the sensitivity and reliability of visual evoked potential to flash ( FVEP ) in detecting bilirubin neurotoxicity and approach the risk parameters of bilirubin neurotoxicity in hyperbilirubinernia newborns. Methods Based on the successful establishment of animal models for acute bilirubin encephalopathy by intraperitoneal infusion of bilirubin with a dosage of 100~200μg /g body weight to 1-weekold guinea pigs, the F-VEP was recorded in animal models and human neonates with hyperbilirubinemia, and the sensitivity and reliability of F-VEP in detecting bilirubin neurotoxicity were evaluated. Results F-VEP features and its P1 latency significantly correlated to brain adenosine triphosphate (ATP) level, neurobehavioral and neuropathological changes in experimental bilirubin encephalopathy ; neonates with hyperbilirubinemia showed significant F-VEP changes characterized by absence of P1 or P1 latency prolonged in 1~7-dayold newborns, especially when the jaundice was caused by immunoincompatibility and infectious diseases. Conclusion F-VEP would be a good discriminator for bilirubin neurotoxicity, and can become a promising technique in monitoring bilirubin encephalopathy.

  2. Why do stroke patients with negative motor evoked potential show poor limb motor function recovery?*

    Institute of Scientific and Technical Information of China (English)

    Zhibin Song; Lijuan Dang; Yanling Zhou; Yanjiang Dong; Haimao Liang; Zhengfeng Zhu; Suyue Pan


    Negative motor evoked potentials after cerebral infarction, indicative of poor recovery of limb motor function, tend to be accompanied by changes in fractional anisotropy values and the cerebral pe-duncle area on the affected side, but the characteristics of these changes have not been reported. This study included 57 cases of cerebral infarction whose motor evoked potentials were tested in the 24 hours after the first inspection for diffusion tensor imaging, in which 29 cases were in the negative group and 28 cases in the positive group. Twenty-nine patients with negative motor evoked potentials were divided into two groups according to fractional anisotropy on the affected side of the cerebral peduncle: a fractional anisotropy < 0.36 group and a fractional anisotropy ≥ 0.36 group. Al patients underwent a regular magnetic resonance imaging and a diffusion tensor imaging examina-tion at 1 week, 1, 3, 6 and 12 months after cerebral infarction. The Fugl-Meyer scores of their he-miplegic limbs were tested before the magnetic resonance and diffusion tensor imaging tions. In the negative motor evoked potential group, fractional anisotropy in the affected cerebral peduncle declined progressively, which was most obvious in the first 1-3 months after the onset of cerebral infarction. The areas and area asymmetries of the cerebral peduncle on the affected side were significantly decreased at 6 and 12 months after onset. At 12 months after onset, the area asymmetries of the cerebral peduncle on the affected side were lower than the normal lower limit value of 0.83. Fugl-Meyer scores in the fractional anisotropy ≥ 0.36 group were significantly higher than in the fractional anisotropy < 0.36 group at 3-12 months after onset. The fractional anisotropy of the cerebral peduncle in the positive motor evoked potential group decreased in the first 1 month after onset, and stayed unchanged from 3-12 months; there was no change in the area of the ce-rebral peduncle in the first 1

  3. On-line analysis of middle latency auditory evoked potentials (MLAEP) for monitoring depth of anaesthesia in laboratory rats

    DEFF Research Database (Denmark)

    Jensen, E W; Nygaard, M; Henneberg, S W


    using neuromuscular blocking agents (NMBA). A number of studies suggest that the Middle Latency Auditory Evoked Potentials (MLAEP) contain information about the state of consciousness in humans. The purpose of this study was to examine whether the AEP could serve as an indicator of depth of anaesthesia...... in rats. The AEP was elicited with a click stimulus and monitored in an 80 ms window synchronised to the stimulus. The AEP was extracted applying an Auto Regressive Model with Exogenous Input (ARX-model) from which a Depth of Anaesthesia Index (DAI) was calculated. DAI was normalised to 100 while awake...

  4. Electrode position and the multi-focal visual-evoked potential: role in objective visual field assessment. (United States)

    Klistorner, A I; Graham, S L; Grigg, J R; Billson, F A


    To improve the performance of visual-evoked potentials (VEP) in the assessment of the human visual field, the multi-focal cortically scaled pattern VEP was recorded up to 250 of eccentricity in normal subjects. Monopolar and varying bipolar electrode positions were used. The monopolar response was strongly biased towards the lower hemifield. Bipolar leads straddling the inion (2 cm above and below) achieved approximately equal signals from the upper and lower visual field. Division into sectors of similar wave-form augments the analysis compared with summed full-field responses. With this technique, the multi-focal VEP can be used to objectively assess the visual field.

  5. Normal and dichromatic color discrimination measured with transient visual evoked potential. (United States)

    Gomes, Bruno D; Souza, Givago S; Rodrigues, Anderson R; Saito, Cézar A; Silveira, Luiz Carlos L; da Silva Filho, Manoel


    It would be informative to have an electrophysiological method to study, in an objective way, the effects of mercury exposure and other neurotoxics on human color vision performance. The purpose of the present work was to study human color discrimination by measuring chromatic difference thresholds with visual evoked potential (VEP). Six young normal trichromats (24 +/- 1 years old) and one deutan (26 years old) were tested. The stimuli consisted of sinusoidal isoluminant chromatic gratings made from chromaticity pairs located along four different color directions centered on two reference points. Heterochromatic flicker photometry (HFP) protocol was used to obtain the isoluminance condition for every subject and for all chromaticity pairs. Spatial frequency was 2 cycles/deg. Presentation mode comprised onset (300 ms)/offset (700 ms) periods. As previously described, we found a negative deflection in the VEP which was related to the chromatic difference: as chromatic difference increased, amplitude increased and latency decreased. VEP response amplitude was plotted against distance in the CIE 1976 color space between the grating chromaticities and fitted with a regression line. We found color thresholds by extrapolating the fitting to null amplitude values. The thresholds were plotted in the CIE 1976 color space as MacAdam ellipses. In normal trichromats the ellipses had small size, low ellipticity, and were vertically oriented. In the deutan subject, the ellipses had large size, high ellipticity, and were oriented towards the deutan copunctal locus. The VEP thresholds were similar to those obtained using grating stimuli and psychophysical procedures, however smaller than those obtained using pseudoisochromatic stimuli (Mollon-Reffin method). We concluded that transient VEP amplitude as a function of contrast can be reliably used in objective studies of chromatic discrimination performance in normal and altered human subjects.

  6. Value of somatosensory evoked potentials in diagnosis, surgical monitoring and prognosis of cervical spondylotic myelopathy

    Institute of Scientific and Technical Information of China (English)

    DING Yu; HU Yong; RUAN Di-ke; CHEN Bo


    Background The value of somatosensory evoked potentials (SEPs) in the diagnosis and prognosis of cervical spondylotic myelopathy, as well as the usefulness of monitoring intraoperative potentials in terms of safety and predictive factors were investigated.Methods Each of the 76 myelopathic patients underwent surgical intervention. According to the wave configurations of the SEPs, the cases were categorised into four groups: Type Ⅰ, Ⅱ, Ⅲ and Ⅳ. The clinical myelopathy disability was classified and the severity of neurological deficits was scored. Clinical function after surgery was evaluated. Preoperative potentials and intraoperative monitoring were categorized. The correlations between evoked potentials detection, monitoring, myelopathy disability and surgical outcome in the different groups were discussed. Results According to the configurations of the SEPs, there were 27 patients (36%) of Type Ⅰ, 30 patients (39%) of Type Ⅱ, 8 patients (11%) of Type Ⅲ, and 11 patients (14%) of Type Ⅳ. The categorised evoked potentials were shown to be significantly associated with the clinical representation of myelopathy (P 〈0.01) and the recovery rate from identifiable SEPs waves (groups A, B and C) was significantly higher than unidentifiable waves (group D, P〈0.01). A deterioration of SEPs was detected in 23 cases (30%), whereas there was no change in 40 cases (53%) and improvements in 13 cases (17%). A significant difference in recovery rates could be observed in various monitoring groups within the short-term follow-up period, while there were no obvious differences in the long-term follow-up groups. Conclusions SEP technique is a valuable and practical tool for the diagnosis, monitoring and prognosis of myelopathy. Classified evoked potentials are well correlated with cervical spondyiotic myelopathy disability, and unidentifiable SEPs waves in patients are indicative of a relatively poor outcome. In addition, intraoperative monitoring of SEPs plays an

  7. NGF-evoked sensitization of muscle fascia nociceptors in humans. (United States)

    Deising, Saskia; Weinkauf, Benjamin; Blunk, James; Obreja, Otilia; Schmelz, Martin; Rukwied, Roman


    Nerve growth factor (NGF) induces local hyperalgesia for a few days after intramuscular injection, but longer-lasting muscle pain upon systemic administration. As the muscle fascia is densely innervated by free nerve endings, we hypothesized a lasting sensitization of fascia nociceptors by NGF. We administered 1 μg NGF (dissolved in 100 μL saline) ultrasound-guided to the fascia of the Musculus erector spinae muscle at the lumbar level of 14 male volunteers and assessed hypersensitivity after 6 hours, and 1, 3, 7, 14, and 21 days. Pain upon mechanical stimuli (constant pressure and dynamic impact), upon exercise and electrically induced M. erector spinae contraction, and upon injection of 100 μL phosphate buffer pH4 (at day 7 and 14 only) to the fascia of both NGF- and saline-treated muscles, was investigated. Injections into the muscle fascia did not cause acute pain. Local heat pain thresholds were unchanged following NGF and saline (control) administration. NGF evoked a lasting (days 1-7) and significant reduction of pressure pain, pressure thresholds, exercise-evoked muscle pain, and hyperalgesia to impact stimuli (12 m/s). Pain upon injected protons was significantly elevated (Pfascia to mechanical and chemical stimuli lasting for up to 2 weeks. As nociceptors in the fascia appear to be particularly prone to sensitization, they may contribute to acute or chronic muscle pain. Copyright © 2012 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

  8. Combined monitoring of evoked potentials during microsurgery for lesions adjacent to the brainstem and intracranial aneurysms

    Institute of Scientific and Technical Information of China (English)

    KANG De-zhi; WU Zan-yi; LAN Qing; YU Liang-hong; LIN Zhang-ya; WANG Chen-yang; LIN Yuan-xiang


    Background Neurophysiologic monitoring during surgery is to prevent permanent neurological injury resulting from surgical manipulation. To improve the accuracy and sensitivity of intraoperative neuromonitoring, combined monitoring of transcranial electrical stimulation motor evoked potentials (TES-MEPs), somatosensory evoked potentials (SSEPs) and brainstem auditory evoked potentials (BAEPs) was attempted in microsurgery for lesions adjacent to the brainstem and intracranial aneurysms.Methods Monitoring of combined TES-MEPs with SSEPs was attempted in 68 consecutive patients with lesions adjacent to the brainstem as well as intracranial aneurysms. Among them, 31 patients (31 operations, 28 of posterior cranial fossa tumors, 3 of posterior circulation aneurysms) were also subjected to monitoring of BAEPs. The correlation of monitoring results and clinical outcome was studied prospectively.Results Combined monitoring of evoked potentials (EPs) was done in 64 (94.1%) of the 68 patients. MEPs monitoring was impossible for 4 patients (5.9%). No complication was observed during the combined monitoring in all the patients. In 45 (66.2%) of the 68 patients, EPs were stable, and they were neurologically intact. Motor dysfunction was detected by MEPs in 8 patients, SSEPs in 5, and BAEPs in 4, respectively.Conclusions A close relationship exists between postoperative motor function and the results of TES-MEPs monitoring.TES-MEPs are superior to SSEPs and BAEPs in detecting motor dysfunction, but combined EPs serve as a safe,effective and invasive method for intraoperative monitoring of the function of the motor nervous system. Monitoring of combined EPs during microsurgery for lesions adjacent to the brainstem and intracranial aneurysms may detect potentially hazardous maneuvers and improve the safety of subsequent procedures.

  9. Evoked potentials are useful for diagnosis of neuromyelitis optica spectrum disorder. (United States)

    Ohnari, Keiko; Okada, Kazumasa; Takahashi, Toshiyuki; Mafune, Kosuke; Adachi, Hiroaki


    Neuromyelitis optica spectrum disorder (NMOSD) has been differentiated from relapsing-remitting multiple sclerosis (RRMS) by clinical, laboratory, and pathological findings, including the presence of the anti-aquaporin 4 antibody. Measurement of evoked potentials (EPs) is often used for the diagnosis of RRMS, although the possibility of applying EPs to the diagnosis of NMOSD has not been investigated in detail. Eighteen patients with NMOSD and 28 patients with RRMS were included in this study. The patients' neurological symptoms and signs were examined and their EPs were recorded. Characteristic findings were absence of visual evoked potentials and absence of motor evoked potentials in the lower extremities in patients with NMOSD, and a delay in these potentials in patients with RRMS. Most patients with NMOSD did not present abnormal subclinical EPs, whereas many patients with RRMS did. None of the patients with NMOSD showed abnormalities in auditory brainstem responses. NMOSD can be differentiated from RRMS by EP data obtained in the early stages of these diseases.

  10. Effect of cerebral lymphatic block on cerebral morphology and cortical evoked potential in rats

    Institute of Scientific and Technical Information of China (English)

    Zuoli Xia; Baoling Sun; Mingfeng Yang; Dongmei Hu; Tong Zhao; Jingzhong Niu


    BACKGROUND: It has been shown that although brain does not contain lining endothelial lymphatic vessel,it has lymphatic drain.Anterior lymphatic vessel in brain tissue plays a key role in introducing brain interstitial fluid to lymphatic system;however,the significance of lymphatic drain and the affect on cerebral edema remains unclear.OBJECTIVE: To investigate the effect of cerebral lymphatic block on cerebral morphology and cortical evoked potential in rats.DESIGN: Randomized controlled animal study.SETTING: Institute of Cerebral Microcirulation of Taishan Medical College and Department of Neurology of Affiliated Hospital.MATERIALS:A total of 63 healthy adult male Wistar rats weighing 300-350 g were selected in this study.Forty-seven rats were used for the morphological observation induced by lymphatic drain and randomly divided into three groups:general observation group(n=12),light microscopic observation group(n=21)and electronic microscopic observation group(n=14).The rats in each group were divided into cerebral lymphatic block subgroup and sham-operation control subgroup.Sixteen rats were divided into cerebral the effect of cerebral lymphatic block on cortical evoked potential,in which the animals were randomly divided into sham-operation group(n=6)and cerebral lymphatic block group(n=10).METHODS:The experiment was carried out in the Institute of Cerebral Microcirculation of Taishan Medical College from January to August 2003.Rats in cerebral lymphatic block group were anesthetized and separated bilateral superficial and deep cervical lymph nodes under sterile condition. Superior and inferior boarders of lymph nodes were ligated the inputting and outputting channels, respectively, and then lymph node was removed so as to establish cerebral lymphatic drain disorder models. Rats in sham-operation control group were not ligated the lymphatic vessel and removed lymph nodes.and other operations were as the same as those in cerebral lymphatic block group

  11. Light scattering changes follow evoked potentials from hippocampal Schaeffer collateral stimulation

    DEFF Research Database (Denmark)

    Rector, D M; Poe, G R; Kristensen, Morten Pilgaard


    -coupled device camera to detect scattered light changes, was lowered to the contralateral dorsal hippocampal surface. Light at 660 +/- 10 (SE) nm illuminated the tissue through optic fibers surrounding the optic probe. An attached bipolar electrode recorded evoked right hippocampal commissural potentials......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...... a complex population synaptic potential that lasted 100-200 ms depending on stimulus intensity and electrode position. Light scattering changes peaked 20 ms after stimuli and occurred simultaneously with population spikes. A long-lasting light scattering component peaked 100-500 ms after the stimulus...

  12. The Analysis of Disparity Evoked Potentials by a New Form of Static Random—Dot Stereograms

    Institute of Scientific and Technical Information of China (English)

    ChuanHou; XuexinZhang


    Purpose:A new form of static random-dot stereograms free of monoular clues was designed as stimulus to elicit disparity evoked potentials.Methods:Disparity evoked potentials were recorded in 40stereo-normal subjects.The stimulator was a white-black static random-dot stereograms generated by a computer and had no monocular clues.Every subject was tested in disparity stim-ulus,zero disparity stimulus,monocuular stimulus and wearing prism condition.Results:A characteristic wide positive wave at about 250ms was consistantly recorded in disparity stimulus,which amy be regarded as evidence of the the pres-ence of stereopsis .In contrast,recordings for zero disparity stimulus,monocular vision,stimulus and wearing prism condition all demonstrated a markedly differ-ence from recording for disparity stimulus.

  13. Visual evoked potentials in dementia: a meta-analysis and empirical study of Alzheimer's disease patients. (United States)

    Pollock, V E; Schneider, L S; Chui, H C; Henderson, V; Zemansky, M; Sloane, R B


    A meta-analytic review of flash and pattern reversal visual evoked potential research indicates that elderly demented patients have longer P100 latencies than age-matched control subjects. In the present empirical research, patients with research diagnoses of probable Alzheimer's disease were compared with sex- and age-matched control subjects using P100 latencies of visual evoked potentials (VEP) elicited by flash and pattern reversal. As compared to control subjects, Alzheimer's disease patients showed significantly longer P100 latencies of the VEP elicited by pattern reversal; the flash P100 only marginally distinguished them. These findings are discussed within the context of VEP recording practices, patient selection, sex and age matching of control subjects, and the visual system.

  14. Characteristics of brain stem auditory evoked potentials in children with hearing impairment due to infectious diseases. (United States)

    Ječmenica, Jovana Radovan; Opančina, Aleksandra Aleksandar Bajec


    Among objective audiologic tests, the most important were tests of brain stem auditory evoked potentials. The objective of the study was to test the configuration, degree of hearing loss, and response characteristics of auditory brain stem evoked potentials in children with hearing loss occurred due to infectious disease. A case control study design was used. The study group consisted of 54 patients referred for a hearing test because of infectious diseases caused by other agents or that occurred as congenital infection. Infectious agents have led to the emergence of various forms of sensorineural hearing loss. We have found deviations from the normal values of absolute and interwave latencies in some children in our group. We found that in the group of children who had the diseases such as purulent meningitis, or were born with rubella virus and cytomegalovirus infection, a retrocochlear damage was present in children with and without cochlear damage.

  15. The effects of halothane on somatosensory and flash visual evoked potentials during operations. (United States)

    Wang, A D; Costa e Silva, I; Symon, L; Jewkes, D


    Intraoperative use of somatosensory evoked potentials (SEP's) to monitor intracranial aneurysm surgery and flash visual evoked potentials (F-VEP's) for parasellar surgery have been routinely employed in our clinic. We found that both EP modalities are sensitive to the changing concentration of our standard hypotensive agent, halothane. The prolongation of the N14-N20 interpeak latency to median nerve stimulation at the wrist, and prolongation of P100 latency with altered configuration of early VEP components to flash light stimulation, appear to be the results of direct pharmacological effects of the agent and not an effect of secondary hypotension. VEP is found easily abolished by halothane at a concentration of 2.0%, while the SEP is more resistant. Halothane is not ideal however when monitoring intraoperative VEP.

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

    DEFF Research Database (Denmark)

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


    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....

  17. Evoked potential correlates of selective attention with multi-channel auditory inputs (United States)

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


    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.

  18. Biomedical signal acquisition with streaming wireless communication for recording evoked potentials. (United States)

    Thie, Johnson; Klistorner, Alexander; Graham, Stuart L


    Commercial electrophysiology systems for recording evoked potentials always connect patients to the acquisition unit via long wires. Wires guarantee timely transfer of signals for synchronization with the stimuli, but they are susceptible to electromagnetic and electrostatic interferences. Though wireless solutions are readily available (e.g. Bluetooth), they introduce high delay variability that will distort the evoked potential traces. We developed a complete wireless acquisition system with a fixed delay. The system supports up to 4 bipolar channels; each is amplified by 20,000× and digitized to 24 bits. The system incorporates the "driven-right-leg" circuit to lower the common noise. Data are continuously streamed using radio-frequency transmission operating at 915 MHz and then tagged with the stimulus SYNC signal at the receiver. The delay, noise level and transmission error rate were measured. Flash visual evoked potentials were recorded monocularly from both eyes of six adults with normal vision. The signals were acquired via wireless and wired transmissions simultaneously. The recording was repeated on some participants within 2 weeks. The delay was constant at 20 ms. The system noise was white and Gaussian (2 microvolts RMS). The transmission error rate was about one per million packets. The VEPs recorded with wireless transmission were consistent with those with wired transmission. The VEP amplitudes and shapes showed good intra-session and inter-session reproducibility and were consistent across eyes. The wireless acquisition system can reliably record visual evoked potentials. It has a constant delay of 20 ms and very low error rate.

  19. 0 to 5 year-old children hearing appraisal by encephalic trunk audition evoked potentials


    Bustamante Mejía, César; Unidad de Otoneurología, Sección Otorrinolaringología, Hospital Central de la Fuerza Aérea del Perú, Lima, Perú


    OBJECTIVE: To analyze hearing development and maturation from 0 to 5 years of age by evaluating latency times with encephalic trunk audition evoked potentials (AEP). MATERIAL AND METHODS: Forty-four 0 to 5 year-old patients were grouped by age and AEP performed with identical parameters; all patients were sedated to avoid interference. RESULTS: Latency times decreased as age increased, denoting age/latency time (V wave) relation as indicator of hearing development and maturation. CONclusiOn: ...

  20. Visual fatigue and visual evoked potentials in multiple sclerosis, glaucoma, ocular hypertension and Parkinson's disease.



    Visual evoked potential (VEP) abnormality is widely used as an objective indication of visual pathophysiology in the diagnosis of multiple sclerosis. One major limitation of this test is that VEP abnormality is not specific to multiple sclerosis. In an attempt to explore ways of making the VEP test more specific, changes were measured in VEPs caused by superimposing upon the VEP stimulus either a flicker or a moving pattern. The rationale was to test for visual fatigueability, since it is kno...

  1. Standard and limitation of intraoperative monitoring of the visual evoked potential



    Visual evoked potential (VEP) has been installed as one of the intraoperative visual function monitoring. It remains unclear, however, whether intraoperative VEP monitoring facilitates as a real time visual function monitoring with satisfactory effectiveness and sensitivity. To evaluate this, relationships between VEP waveform changes and postoperative visual function were analysed retrospectively. Intraoperative VEP monitoring was carried out for 106 sides (eyes) in 53 surgeries, including t...

  2. Latency of auditory evoked potential monitoring the effects of general anesthetics on nerve fibers and synapses


    Bowan Huang; Feixue Liang; Lei Zhong; Minlin Lin; Juan Yang; Linqing Yan; Jinfan Xiao; Zhongju Xiao


    Auditory evoked potential (AEP) is an effective index for the effects of general anesthetics. However, it’s unknown if AEP can differentiate the effects of general anesthetics on nerve fibers and synapses. Presently, we investigated AEP latency and amplitude changes to different acoustic intensities during pentobarbital anesthesia. Latency more regularly changed than amplitude during anesthesia. AEP Latency monotonically decreased with acoustic intensity increase (i.e., latency-intensity curv...

  3. Air pollution is associated with brainstem auditory nuclei pathology and delayed brainstem auditory evoked potentials


    Calderón-Garcidueñas, Lilian; D’Angiulli, Amedeo; Kulesza, Randy J.; Torres-Jardón, Ricardo; Osnaya, Norma; Romero, Lina; Keefe, Sheyla; Herritt, Lou; Brooks, Diane M.; Avila-Ramirez, Jose; Delgado-Chávez, Ricardo; Medina-Cortina, Humberto; González-González, Luis Oscar


    We assessed brainstem inflammation in children exposed to air pollutants by comparing brainstem auditory evoked potentials (BAEPs) and blood inflammatory markers in children age 96.3± 8.5 months from highly polluted (n=34) versus a low polluted city (n=17). The brainstems of nine children with accidental deaths were also examined. Children from the highly polluted environment had significant delays in wave III (t(50)=17.038; p

  4. Vestibular evoked myogenic potential testing as an objective measure of vestibular stimulation with cochlear implants. (United States)

    Parkes, William J; Gnanasegaram, Joshua J; Cushing, Sharon L; McKnight, Carmen L; Papsin, Blake C; Gordon, Karen A


    To determine if vestibular potentials could be elicited with electrical stimulation from cochlear implants. Prospective cohort study. Vestibular responsiveness to electrical stimulation from cochlear implants was assessed via vestibular evoked myogenic potential (VEMP) testing in 53 pediatric and young adult patients. Thirty-one participants (58%) showed at least one vestibular potential in response to acoustic stimulation; 33 (62%) had an electrically evoked vestibular response. A cervical VEMP (cVEMP) was present in 45 of the 96 tested ears (47%) in response to acoustic stimulation, and in 34 ears (35%) with electrical stimulation. An ocular VEMP (oVEMP) was elicited acoustically in 25 ears (26%) and electrically in 34 (35%) ears. In the ears with absent responses to acoustic stimuli, electrically evoked cVEMPs and oVEMPs were present in 14 (27%) and 18 (25%) ears, respectively. Electric VEMPs demonstrated shorter latencies than acoustic VEMPs (P VEMPs was seen at high stimulation levels (P .05). VEMPs can be elicited with electrical stimulation in a proportion of children with cochlear implants, demonstrating current spread from the cochlea to the vestibular system. The presence of electric VEMPs in acoustically nonresponsive ears, along with the shorter latencies of electrically driven VEMPs, suggests that electrical current can bypass the otoliths and directly stimulate vestibular neural elements. 4. Laryngoscope, 2016 127:E75-E81, 2017. © 2016 The American Laryngological, Rhinological and Otological Society, Inc.

  5. Lack of habituation of evoked visual potentials in analytic information processing style: evidence in healthy subjects. (United States)

    Buonfiglio, Marzia; Toscano, M; Puledda, F; Avanzini, G; Di Clemente, L; Di Sabato, F; Di Piero, V


    Habituation is considered one of the most basic mechanisms of learning. Habituation deficit to several sensory stimulations has been defined as a trait of migraine brain and also observed in other disorders. On the other hand, analytic information processing style is characterized by the habit of continually evaluating stimuli and it has been associated with migraine. We investigated a possible correlation between lack of habituation of evoked visual potentials and analytic cognitive style in healthy subjects. According to Sternberg-Wagner self-assessment inventory, 15 healthy volunteers (HV) with high analytic score and 15 HV with high global score were recruited. Both groups underwent visual evoked potentials recordings after psychological evaluation. We observed significant lack of habituation in analytical individuals compared to global group. In conclusion, a reduced habituation of visual evoked potentials has been observed in analytic subjects. Our results suggest that further research should be undertaken regarding the relationship between analytic cognitive style and lack of habituation in both physiological and pathophysiological conditions.

  6. Multimodal evoked potentials follow up in multiple sclerosis patients under fingolimod therapy. (United States)

    Iodice, R; Carotenuto, A; Dubbioso, R; Cerillo, I; Santoro, L; Manganelli, F


    Clinical trials have shown the therapeutic effect of fingolimod in reducing disease activity in relapsing-remitting multiple sclerosis (RR-MS), but its influence on nervous conduction assessed by evoked potentials (EPs) has not been previously investigated. EP data of 20 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 Status Scale (EDSS). During pre-treatment period (1year) EDSS worsened while one year after fingolimod treatment EDSS remained stable. From t-1 to t0 VEP, SEP, MEP and EP sum score worsened while from t0 to t+1 VEP, SEP and EP sum score improved, and MEP score remain stable. VEP and SEP were related to EDSS at baseline (t=-1), while MEP and total EP sum score were related to EDSS at all time points. 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 on pathway underweighted in EDSS. EPs are useful to evaluate fingolimod effects in clinical practice. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. [Early prognosis in severe cranio-cerebral trauma using the Glasgow Coma Score and evoked potentials]. (United States)

    Riffel, B; Stöhr, M; Graser, W; Trost, E; Baumgärtner, H


    During 72 h following severe head injury, 103 patients in acute posttraumatic coma were assessed by clinical examinations (documented by Glasgow Coma Score) and brain stem auditory evoked potentials (BAEP) as well as short-latency somatosensory evoked potentials (SEP) following median-nerve stimulation. Patient outcomes were classified at 6 months or more according to the following categories: good recovery, severely disabled or vegetative, and brain dead. Patients who had died of systemic complications (pneumonia, septicemia, renal failure, etc.) were excluded from the study. The Glasgow Coma Score was reliable in forecasting a favorable outcome; all patients with a Score over 9 points had a good recovery. The Glasgow Coma Score was not reliable in predicting an unfavorable outcome, however; some patients with the lowest possible Glasgow Coma Score (3 points) at the early clinical examination survived with good recovery. The BAEPs were reliable predictors of an unfavorable outcome; the outcome was unfavorable when a missing wave V or more missing waves pointed toward a secondary brainstem lesion. Normal BAEPs were not reliable, however, in predicting a favorable outcome. SEP data served as a prognostic indicator of unfavorable as well as favorable outcomes. In summary, evoked potentials add valuable information to the clinical examination in assessing a patient's outcome after severe head injury.

  8. Temporal processing and long-latency auditory evoked potential in stutterers. (United States)

    Prestes, Raquel; de Andrade, Adriana Neves; Santos, Renata Beatriz Fernandes; Marangoni, Andrea Tortosa; Schiefer, Ana Maria; Gil, Daniela

    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. To characterize the temporal processing and long-latency auditory evoked potential in stutterers and to compare them with non-stutterers. 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. 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. Stutterers have poor performance in temporal processing and higher latency values for N2 and P3 components. Copyright © 2017 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

  9. Direct cortical stimulation but not transcranial electrical stimulation motor evoked potentials detect brain ischemia during brain tumor resection. (United States)

    Li, Fenghua; Deshaies, Eric M; Allott, Geoffrey; Canute, Gregory; Gorji, Reza


    Motor evoked potentials (MEPs) elicited by both direct cortical stimulation (DCS) and transcranial electrical stimulation are used during brain tumor resection. Parallel use of direct cortical stimulation motor evoked potentials (DCS-MEPs) and transcranial electrical stimulation motor evoked potentials (TCeMEPs) has been practiced during brain tumor resection. We report that DCS-MEPs elicited by direct subdural grid stimulation, but not TCeMEPs, detected brain ischemia during brain tumor resection. Following resection of a brainstem high-grade glioma in a 21-year-old, the threshold of cortical motor-evoked-potentials (cMEPs) increased from 13 mA to 20 mA while amplitudes decreased. No changes were noted in transcranial motor evoked potentials (TCMEPs), somatosensory evoked potentials (SSEPs), auditory evoked potentials (AEPs), anesthetics, or hemodynamic parameters. Our case showed the loss of cMEPs and SSEPs, but not TCeMEPs. Permanent loss of DCS-MEPs and SSEPs was correlated with permanent left hemiplegia in our patient even when appropriate action was taken. Parallel use of DCS- and TCeMEPs with SSEPs improves sensitivity of intraoperative detection of motor impairment. DCS may be superior to TCeMEPs during brain tumor resection.

  10. Vestibular evoked potentials (VsEPs) of cortical origin produced by impulsive acceleration applied at the nasion. (United States)

    Todd, Neil P M; McLean, Aisha; Paillard, Aurore; Kluk, Karolina; Colebatch, James G


    We report the results of a study to record vestibular evoked potentials (VsEPs) of cortical origin produced by impulsive acceleration (IA). In a sample of 12 healthy participants, evoked potentials recorded by 70 channel electroencephalography were obtained by IA stimulation at the nasion and compared with evoked potentials from the same stimulus applied to the forefingers. The nasion stimulation gave rise to a series of positive and negative deflections in the latency range of 26-72 ms, which were dependent on the polarity of the applied IA. In contrast, evoked potentials from the fingers were characterised by a single N50/P50 deflection at about 50 ms and were polarity invariant. Source analysis confirmed that the finger evoked potentials were somatosensory in origin, i.e. were somatosensory evoked potentials, and suggested that the nasion evoked potentials plausibly included vestibular midline and frontal sources, as well as contributions from the eyes, and thus were likely VsEPs. These results show considerable promise as a new method for assessment of the central vestibular system by means of VsEPs produced by IA applied to the head.

  11. Sugammadex to reverse neuromuscular blockade and provide optimal conditions for motor-evoked potential monitoring

    Directory of Open Access Journals (Sweden)

    Mehdi Trifa


    Full Text Available Sugammadex is a novel pharmacologic agent, which reverses neuromuscular blockade (NMB via a mechanism that differs completely from acetylcholinesterase inhibitors. By encapsulating rocuronium, sugammadex can provide recovery of neuromuscular function even when there is a profound degree of NMB. We report anecdotal experience with the use of sugammadex to reverse NMB to facilitate intraoperative neurophysiological monitoring (motor evoked potentials in an adolescent with scoliosis during posterior spinal fusion. Its potential application in this unique clinical scenario is discussed, and potential dosing schemes are reviewed.

  12. Changes of evoked potentials and evaluation of mild hypothermia for treatment of severe brain injury

    Institute of Scientific and Technical Information of China (English)


    Objective: To observe the changes of evoked pote ntials after severe brain injury and the effect of mild hypothermia on acute sev ere brain injury.   Methods: A total of 44 patients with severe closed head injury (GCS 3-8, admitted within 10 hours from injury) admitted from May 1998 to March 1999 were selected for this study. All patients were admitted into the intensiv e care unit and divided into 2 groups, Group A (GCS 3-5) and Group B (GCS 6 -8). Patients were also randomly assigned to either normothermia or hypothermia subgroups. Patients in the hypothermia group were cooled to 32-34℃. Median nerve short-latency somatosensory evoked potentials (SLSEP) and brain stem aud itory evoked potentials (BAEP) were recorded before cooling and 4, 24, 48, 72, 9 6 and 120 hours, respectively after cooling and temperature resuming. SLSEP and BAEP were measured at the same time in the normothermia group (control group). T he changes of evoked potentials (EP) were analyzed by statistical methods.   Results: In the Group B, N20 amplitudes in SLSEP and I/V amplitudes in BAEP after mild hypothermia treatment in the hypothermia group dif fered significantly from those in the control group (P<0.05). However, in the Group A, no significant difference in all paramet ers was found.   Conclusions: These results demonstrate that mild hypothermia tr eatment (32-34℃) in the Group B has a significant neuroelectrophysiological effect on severe brain injury. Nevertheless, the effect of mild hypothermia in t he Group A is not apparent and needs further studying.

  13. The effect of changes in perilymphatic K+ on the vestibular evoked potential in the guinea pig. (United States)

    Kingma, C M; Wit, H P


    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 a sufficient volume to cause rupture, all ears showed a complete disappearance of VsEP, followed by partial recovery. To investigate the effect of perilymphatic potassium concentration on the vestibular sensory and neural structures, different concentrations of KCl were injected directly into the vestibule. The KCl injections resulted in a dose-dependent decrease of VsEP, followed by a dose-dependent slow recovery. This animal model clearly shows a disturbing effect of a higher than normal K(+) concentration in perilymph on the vestibular and neural structures in the inner ear. Potassium intoxication is the most probable explanation for the observed effects. It is one of the explanations for Menière attacks.


    Directory of Open Access Journals (Sweden)

    Sanjeev Kumar


    Full Text Available 20 diabetic (Type 1 patients have been studied in order to investigate the possible effects of the type 1 diabetes mellitus on the central nervous system by means of pattern shift visual evoked potentials. Patients with diabetic retinopathy , glaucoma and cataract were excluded from the study. To evaluate central optic pathways involvement in diabetics , visual evoked po tentials (VEP , in particular the latency of positive peak (P100 , were studied in 20 patients and 20 normal controls using reversal pattern VEP. P100 latency was significantly increased in diabetics. A positive co - relation was also found between latencies of VEP and duration of disease. Relationship between blood sugar level and P 100 wave latencies and amplitudes in diabetic patients was not significant . VEP measurement seems a simple and sensitive method for detecting early involvement and changes in opti c pathways in diabetics

  15. Spatial filtering based on canonical correlation analysis for classification of evoked or event-related potentials in EEG data. (United States)

    Spüler, Martin; Walter, Armin; Rosenstiel, Wolfgang; Bogdan, Martin


    Classification of evoked or event-related potentials is an important prerequisite for many types of brain-computer interfaces (BCIs). To increase classification accuracy, spatial filters are used to improve the signal-to-noise ratio of the brain signals and thereby facilitate the detection and classification of evoked or event-related potentials. While canonical correlation analysis (CCA) has previously been used to construct spatial filters that increase classification accuracy for BCIs based on visual evoked potentials, we show in this paper, how CCA can also be used for spatial filtering of event-related potentials like P300. We also evaluate the use of CCA for spatial filtering on other data with evoked and event-related potentials and show that CCA performs consistently better than other standard spatial filtering methods.

  16. Comparison of cervical and ocular vestibular evoked myogenic potentials in dancers and non-dancers


    Sujeet Kumar Sinha; Vaishnavi Bohra; Himanshu Kumar Sanju


    The objective of the study was to assess the sacculocollic and otolith ocular pathway function using cervical vestibular evoked myogenic potentials (cVEMP) and ocular vestibular myogenic potentials (oVEMP) in dancers and non dancers. Total 16 subjects participated in the study. Out of 16 participants, 8 were trained in Indian classical form of dance (dancers) and other 8 participants who were not trained in any dance form (non dancers). cVEMP and oVEMP responses were recorded for all the subj...

  17. Multifocal topographic visual evoked potential: improving objective detection of local visual field defects. (United States)

    Klistorner, A I; Graham, S L; Grigg, J R; Billson, F A


    To investigate the relationships between the pattern stimulation of different parts of the visual field (up to 25 degrees of eccentricity), the electrode position, and the cortical response to improve objective detection of local visual field defects. The human visual evoked potential (VEP) was assessed using multifocal pseudorandomly alternated pattern stimuli that were cortically scaled in size. Monopolar and bipolar electrode positions were used. The visual field was investigated up to 26 degrees of eccentricity. Twelve normal subjects and seven subjects with visual field defects of different nature were studied. Although the monopolar response is heavily biased toward the lower hemifield, bipolar leads overlying the active occipital cortex (straddling the inion) demonstrate good signals from all areas of the visual field tested. The amplitude is almost equal for the averaged upper and lower hemifields, but the polarity is opposite, causing partial cancellation of the full-field VEP. The degree of cancellation depends mainly on latency differences between the vertical hemifields. The bipolar VEP corresponded well with Humphrey visual field defects, and it showed a loss of signal in the scotoma area. The multifocal VEP demonstrates good correspondence with the topography of the visual field. Recording with occipital bipolar electrode placement is superior to standard monopolar recording. To avoid a full-field cancellation effect, a separate evaluation of upper and lower hemifields should be used for the best assessment of retinocortical pathways. This technique represents a significant step toward the possible application of the multifocal VEP to objective detection of local defects in the visual field.

  18. Steady-state sweep visual evoked potential processing denoised by wavelet transform (United States)

    Weiderpass, Heinar A.; Yamamoto, Jorge F.; Salomão, Solange R.; Berezovsky, Adriana; Pereira, Josenilson M.; Sacai, Paula Y.; de Oliveira, José P.; Costa, Marcio A.; Burattini, Marcelo N.


    Visually evoked potential (VEP) is a very small electrical signal originated in the visual cortex in response to periodic visual stimulation. Sweep-VEP is a modified VEP procedure used to measure grating visual acuity in non-verbal and preverbal patients. This biopotential is buried in a large amount of electroencephalographic (EEG) noise and movement related artifact. The signal-to-noise ratio (SNR) plays a dominant role in determining both systematic and statistic errors. The purpose of this study is to present a method based on wavelet transform technique for filtering and extracting steady-state sweep-VEP. Counter-phase sine-wave luminance gratings modulated at 6 Hz were used as stimuli to determine sweep-VEP grating acuity thresholds. The amplitude and phase of the second-harmonic (12 Hz) pattern reversal response were analyzed using the fast Fourier transform after the wavelet filtering. The wavelet transform method was used to decompose the VEP signal into wavelet coefficients by a discrete wavelet analysis to determine which coefficients yield significant activity at the corresponding frequency. In a subsequent step only significant coefficients were considered and the remaining was set to zero allowing a reconstruction of the VEP signal. This procedure resulted in filtering out other frequencies that were considered noise. Numerical simulations and analyses of human VEP data showed that this method has provided higher SNR when compared with the classical recursive least squares (RLS) method. An additional advantage was a more appropriate phase analysis showing more realistic second-harmonic amplitude value during phase brake.

  19. Combined application of three evoked potentials to improve the diagnosis of multiple sclerosis

    Institute of Scientific and Technical Information of China (English)

    Xiaoyi Li


    BACKGROUND:It is very important to find out the focal sites for the ealy diagnosis of multiple sclerosis,especially the discovery of tiny or potential focal site,so that multiple sclerosis can be diagnosed at the early poriod (the first attack)or when the focus has not displayed completely.and the evoked potential can discover the abnormality of the pathway between spinal cord to cerebral cortex.OBJECTIVE:To observe the values of motor evoked potential(MEP),somatosensory evoked potential(SEP) and evoked-related potential(P300)in the diagnosis of multiple sclerosis.DESIGN:A case-controlled study.SETFING:Neuroelectrophysiological Center of Guizhou Provincial People's Hospital. PARTICIPANTS:Twenty-five outpatients or inpatients with multiple sclerosis were selected from the Department of Neurology,Guizhou Provincial People's Hospital from October 2001 to March 2005.The patients were diagnosed according to the diagnostic standards of multiple sclerosis suggested by Poser et al. In 1983 and MRI examination.There were 17 males and 8 females,aged 18-65 years old With an average of 39 years.and their disease courses ranged from 6 months to 5 years.Meanwhile.30 healthy physical examinees were selected in our hospital as the control group,and they all had no abnormality by detailed inquisition.physical examination and examination of nervous system,including 15 males and 5 females,aged 20-66 years old.All the enrolled subjects were informed and agreed with the detections.METHODS:①The MEP,SEP and P300 were detected with synergy evoked potential equipment(Oxford Instruments,UK)in all the 25 patients with multiple sclerosis and 20 healthy subjects.②Standards for judging the abnormalities of evoked potentials:The abnormalities referred to deletion of wave form or the latency was prolonged by more than the reference value of normal subject±3SD.③The differences of measurement data were compared with the t test.MAIN OUTCOME MEASURES:The results of MEP,SEP and P300 in the 25

  20. Reduced evoked motor and sensory potential amplitudes in obstructive sleep apnea patients. (United States)

    Mihalj, Mario; Lušić, Linda; Đogaš, Zoran


    It is unknown to what extent chronic intermittent hypoxaemia in obstructive sleep apnea causes damage to the motor and sensory peripheral nerves. It was hypothesized that patients with obstructive sleep apnea would have bilaterally significantly impaired amplitudes of both motor and sensory peripheral nerve-evoked potentials of both lower and upper limbs. An observational study was conducted on 43 patients with obstructive sleep apnea confirmed by the whole-night polysomnography, and 40 controls to assess the relationship between obstructive sleep apnea and peripheral neuropathy. All obstructive sleep apnea subjects underwent standardized electroneurographic testing, with full assessment of amplitudes of evoked compound muscle action potentials, sensory neural action potentials, motor and sensory nerve conduction velocities, and distal motor and sensory latencies of the median, ulnar, peroneal and sural nerves, bilaterally. All nerve measurements were compared with reference values, as well as between the untreated patients with obstructive sleep apnea and control subjects. Averaged compound muscle action potential and sensory nerve action potential amplitudes were significantly reduced in the nerves of both upper and lower limbs in patients with obstructive sleep apnea compared with controls (P motor and sensory peripheral nerves. Clinical/subclinical axonal damage exists in patients with obstructive sleep apnea to a greater extent than previously thought.

  1. Visual Evoked Potentials to Light Flashes in Captive Rhesus Monkeys: A Study Reflecting Cerebral Cortical Activity and Brain Maturation

    Directory of Open Access Journals (Sweden)

    S.A. Solís-Chávez


    Full Text Available Visual evoked potentials (VEPs are useful electrophysiological diagnostic tools for evaluating retinal response of the visual cortex and detecting its functional integrity in humans and animals. To analyze the VEPs and physiologic response of the visual pathway of a random population of captive-bred monkeys of the Macaca mulatta species throughout different physiologic stages after stimulation with stroboscopic light flashes. In this study we used 20 non-human primates (M. mulatta, 10 males and 10 females, divided into five age-dependant cohorts of 2 males and 2 females. Two replicable negative waveforms and one positive were recorded, as reliable indicators of electrical conductivity at specific anatomical nuclei of the visual pathways. Statistically significant differences were primarily observed in group 1 when compared against the remaining groups for the three evaluated waveforms. Waveform morphology characteristically presented steady deviations related to ontogenetic development of the studied population.

  2. Characteristics of brainstem auditory evoked potentials of students studying folk dance

    Institute of Scientific and Technical Information of China (English)

    Yunxiang Li; Yuzhen Zhu


    BACKGROUND:Previous experiments have demonstrated that brainstem auditory evoked potential is affected by exercise,exercise duration,and frequency. OBJECTIVE:Comparing the brainstem auditory evoked potential of students studying folk dance to students studying other subjects.DESIGN:Observational contrast study. SETTING:Physical Education College,Shandong Normal University PARTICIPANTS:Fifty-five female students were enrolled at Shandong Normal University between September and December in 2005,including 21 students that studied folk dance and 34 students that studied other subjects.The age of the folk dance students averaged(19±1)years and dance training length was(6.0 ±1.5)years.The students that studied other subjects had never taken part in dance training or other physical training,and their age averaged(22±1)years,body height averaged(162±5)cm,body mass averaged(51 ±6)kg.All subjects had no prior ear disease or history of other neurological disorders.All students provided informed consent for the experimental project. METHODS:The neural electricity tester,NDI-200(Shanghai Poseidon Medical Electronic Instrument Factory)was used to examine and record Brainstem Auditory Evoked Potential values of the subjects during silence,as well as to transversally analyze the Brainstem Auditory Evoked Potential values.The electrode positions were cleaned and degreased with soapy water,followed by ethanol.The selected bipolar electrodes were situated on the head:recording electrodes were placed at the Baihui acupoint,and the reference electrode was placed at the mastoid of the measured ear,with grounding electrodes in the center of the forehead.Brainstem Auditory Evoked Potential values were elicited by monaural stimulation of a "click" though an earphone; the other ear was sheltered by the white noise.The click intensity was 102 db,the stimulation frequency was 30 Hz,the bandpass filters were 1 000-3 000 Hz,the sensitivity was 5 μV,and a total of 2 000 sweeps were

  3. Appropriate stimulation in visual evoked potential to evaluate visual perception state of athletes

    Institute of Scientific and Technical Information of China (English)

    Yunxiang Li; Yuzhen Zhu


    BACKGROUND: Several studies have demonstrated that visual evoked potentials can be influenced by sport events. To the best of our knowledge, there are no specific parameters for the most appropriate stimulation for evaluating the functional state of athletes. OBJECTIVE: To investigate the best stimulation in visual evoked potential to apply to functional evaluation of athletes. DESIGN, TIME AND SETTING: Ninety-five, healthy students from the Shandong Normal University took part in an observational, contrast study. PARTICIPANTS: All active participants were male. Sixty-five students majored in physical education, and had participated in exercise for the duration of (4.26±3.08) years. An additional 30 students majored in other subjects. METHODS: The neural electricity tester, NDI-200, was adapted to examine and record visual evoked potential with varying probes using bipolar electrodes attached to the head of all the participants in a dark room. The visual evoked potential values were analyzed transversally. A chessboard pattern reversal method was applied with the following parameters: 2 Hz stimulation frequency, brightness of 90 cdp, 80% contrast, 1-100 Hz bandpass filters, and 10 μ V sensitivity; 100 responses were averaged. MAIN OUTCOME MEASURES: latency, peak latencies, and inter-peak latencies were measured in N75, P100, N145 with varying probe stimulations. RESULTS: (1) Comparisons between the little check, middle check, and big check stimulation, demonstrated that the common tendencies in visual evoked potential indexes of the two groups of N75 latency were successively shorter and N145 were longer. P100-N145 peak latency was decreased and each inter-peak latency was longer. (2) Changes of N75, P10o, and NI45 with different check stimulations in the physical education student group: after compared with the middle check stimulation, N75 latency was significantly longer (P<0.01), and N75-P100 inter-peak latency (P<0.05) and N75-N145 inter-peak latency were

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

    Directory of Open Access Journals (Sweden)

    Mozhgan Masoom


    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.

  5. The investigation of cortical auditory evoked potentials responses in young adults having musical education. (United States)

    Polat, Zahra; Ataş, Ahmet


    In the literature, music education has been shown to enhance auditory perception for children and young adults. When compared to young adult non-musicians, young adult musicians demonstrate increased auditory processing, and enhanced sensitivity to acoustic changes. The evoked response potentials associated with the interpretation of sound are enhanced in musicians. Studies show that training also changes sound perception and cortical responses. The earlier training appears to lead to larger changes in the auditory cortex. Most cortical studies in the literature have used pure tones or musical instrument sounds as stimuli signals. The aim of those studies was to investigate whether musical education would enhance auditory cortical responses when speech signals were used. In this study, the speech sounds extracted from running speech were used as sound stimuli. Non-randomized controlled study. The experimental group consists of young adults up to 21 years-old, all with a minimum of 4 years of musical education. The control group was selected from young adults of the same age without any musical education. The experiments were conducted by using a cortical evoked potential analyser and /m/, /t/ /g/ sound stimulation at the level of 65 dB SPL. In this study, P1 / N1 / P2 amplitude and latency values were measured. Significant differences were found in the amplitude values of P1 and P2 (p0.05). The results obtained in our study indicate that musical experience has an effect on the nervous system and this can be seen in cortical auditory evoked potentials recorded when the subjects hear speech.

  6. Flash visual evoked potential monitoring of optic tract function during macroelectrode-based pallidotomy. (United States)

    Bonaroti, E A; Rose, R D; Kondziolka, D; Baser, S; Lunsford, L D


    Posteroventral pallidotomy (PVP) has received renewed interest as an ablative procedure for the symptomatic treatment of Parkinson's disease. In previous reports, the proximity of the optic tract to the lesion target in the globus pallidus internus has resulted in the occurrence of visual field deficits in as much as 14% of patients. The authors have used intraoperative visual evoked potentials (VEPs) during PVP to reduce this risk. All procedures were performed in awake patients. Flash stimuli were delivered to each eye via fiberoptic sources. Baseline flash VEPs were recorded at O1/Cz (left visual cortex to vertex), Oz/Cz (midline visual cortex to vertex), and O2/Cz (right visual cortex to vertex) for OS, OU, and OD stimulation. Epochs were acquired before and after localization, after macroelectrode stimulation, after temporary thermal lesioning, and after permanent thermal lesioning. Forty-seven patients underwent a total of 59 procedures. Visual evoked potentials were recorded reproducibly in all patients. In 11 procedures, VEP changes were reported, including six amplitude changes (10-80%), six latency shifts (3-10 msec), and one report of "variability." In four procedures, VEP changes prompted a change in target coordinates. One false-positive and one false-negative VEP change were encountered. The only confirmed visual deficit was a superior quadrantanopsia, present on formal fields, but clinically asymptomatic. The authors conclude that VEPs may be useful for procedures performed in the awake patient because of the lack of anesthetic-induced variability. The 1.7% visual morbidity reported here (one in 59 patients) compares favorably with other series using microelectrodes. Visual evoked potentials may be a useful monitoring technique to reduce the incidence of clinically significant visual morbidity during pallidotomy, especially during formal lesioning of the ventral pallidum adjacent to the optic tract.

  7. Brain evoked potential use in a physical medicine and rehabilitation setting. (United States)

    Rappaport, M; Hopkins, K; Hall, K; Belleza, T; Berrol, S


    The objective of this effort was to explore the use of evoked potential (EP) procedure on a head injury unit in a Department of Physical Medicine and Rehabilitation. The method employed both auditory and visual stimulation presented bilaterally to various patients. Recordings of the brain's responses to such stimulation were obtained. Results permitted evaluation of brain stem, subcortical and cortical functioning, ipsilaterally, contralaterally, and bilaterally. EP data provided useful information for patient assessment and rehabilitation planning for head injured patients--particularly for those who were unable to cooperate in their own examination.

  8. Effect of Acupuncture on the Auditory Evoked Brain Stem Potential in Parkinson's Disease

    Institute of Scientific and Technical Information of China (English)

    王玲玲; 何崇; 刘跃光; 朱莉莉


    @@ Under the auditory evoked brain stem potential (ABP) examination, the latent period of V wave and the intermittent periods of III-V peak and I-V peak were significantly shortened in Parkinson's disease patients of the treatment group (N=29) after acupuncture treatment. The difference of cumulative scores in Webster's scale was also decreased in correlation analysis. The increase of dopamine in the brain and the excitability of the dopamine neurons may contribute to the therapeutic effects, in TCM terms, of subduing the pathogenic wind and tranquilizing the mind.

  9. Assessment of an ICA-based noise reduction method for multi-channel auditory evoked potentials (United States)

    Mirahmadizoghi, Siavash; Bell, Steven; Simpson, David


    In this work a new independent component analysis (ICA) based method for noise reduction in evoked potentials is evaluated on for auditory late responses (ALR) captured with a 63-channel electroencephalogram (EEG) from 10 normal-hearing subjects. The performance of the new method is compared with a single channel alternative in terms of signal to noise ratio (SNR), the number of channels with an SNR above an empirically derived statistical critical value and an estimate of hearing threshold. The results show that the multichannel signal processing method can significantly enhance the quality of the signal and also detected hearing thresholds significantly lower than with the single channel alternative.

  10. Evaluation of New Methods for Artifacts Rejection in Evoked Auditory Steady-State Potentials

    Directory of Open Access Journals (Sweden)

    Cyndi González Alfonso


    Full Text Available This paper presents two alternative methods to the traditional method of artifact rejectionequipment currently used in evoked potential recording steady state (ASSR in order to improveefficiency based on the use of a larger number of individual records. The first method proposedis to replace the traditional use of rejection threshold amplitude, while the second version is afaster implementation of the weighted averaging used today, which is applicable also in thetransient Auditory Brainstem Response (ABR. These changes have been made in order toimplement these methods in a real time microprocessor.

  11. A programmable acoustic stimuli and auditory evoked potential measurement system for objective tinnitus diagnosis research. (United States)

    Ku, Yunseo; Ahn, Joong Woo; Kwon, Chiheon; Suh, Myung-Whan; Lee, Jun Ho; Oh, Seung Ha; Kim, Hee Chan


    This paper presents the development of a single platform that records auditory evoked potential synchronized to specific acoustic stimuli of the gap prepulse inhibition method for objective tinnitus diagnosis research. The developed system enables to program various parameters of the generated acoustic stimuli. Moreover, only by simple filter modification, the developed system provides high flexibility to record not only short latency auditory brainstem response but also late latency auditory cortical response. The adaptive weighted averaging algorithm to minimize the time required for the experiment is also introduced. The results show that the proposed algorithm can reduce the number of the averaging repetitions to 70% compared with conventional ensemble averaging method.

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

    DEFF Research Database (Denmark)

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


    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...

  13. Effect of acupuncture on the auditory evoked brain stem potential in Parkinson's disease. (United States)

    Wang, Lingling; He, Chong; Liu, Yueguang; Zhu, Lili


    Under the auditory evoked brain stem potential (ABP) examination, the latent period of V wave and the intermittent periods of III-V peak and I-V peak were significantly shortened in Parkinson's disease patients of the treatment group (N = 29) after acupuncture treatment. The difference of cumulative scores in Webster's scale was also decreased in correlation analysis. The increase of dopamine in the brain and the excitability of the dopamine neurons may contribute to the therapeutic effects, in TCM terms, of subduing the pathogenic wind and tranquilizing the mind.

  14. A Case Report of Intraoperative Monitoring During the Spinal Surgery by Means of Somatosensory Evoked Potentials

    Directory of Open Access Journals (Sweden)

    S.K. Shakoori


    Full Text Available Introduction : To prevent spinal lesions during surgery we can use somatosensory evoked potentials (SSEP to monitor the patients who are under surgery particularly the ones under the spinal cord surgery. Case Report: The following case refers to the monitoring of a 23 year – old youth with the use of Intraoperative SSEP who has been under the operation of tumor removal with the diagnosis of space occupying mass in the conous region of spine in Tabriz Shohada Hospital. Conclusion: SSEP study for left tibial nerve after surgery was the same as before surgery. Pathology diagnosis was epandymom. Patient gave recovery process in few days.

  15. Trigeminal somatosensory evoked potentials. A review of the literature as applicable to oral dysaesthesias. (United States)

    Bennett, A J; Wastell, D G; Barker, G R; Blackburn, C W; Rood, J P


    Oro-facial sensory impairment is a common event following third molar extractions, osteotomies and maxillo-facial trauma. Trigeminal somatosensory-evoked potentials (TSEPs) may offer an objective means of assessing neuronal function in such cases. TSEPs may be recorded non-invasively in man following peripheral stimulation of the trigeminal nerve, the principal nerve of oro-facial sensation. TSEP recording has gained popularity over the last decade and it is thus timely to review experimental methods and proven clinical applications in the light of recent interest in this technique within oral and maxillo-facial surgery.

  16. Visual evoked potentials in optic nerve injury--does it merit to be mentioned?

    Directory of Open Access Journals (Sweden)

    Mahapatra A


    Full Text Available The value of Visual Evoked Potentials (VEP in the management of indirect optic nerve injury was prospectively studied in 78 patients. The initial VEPs were normal in 10, abnormal in 29 and absent in 39 patients. All 10 patients with normal VEP showed visual recovery. Amongst 29 patients with abnormal VEP, 26 (86.6% showed improvement. In 39 patients initial VEPs showed no wave, however, subsequent VEP recordings demonstrated wave formation. Thus in 31 patients repeated VEP recordings failed to demonstrate wave formation, and none of them improved. This study, thus brings out the high predictive value of both positive and negative VEPs.

  17. 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.


    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...

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

    DEFF Research Database (Denmark)

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


    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...... dorsum, and the subjects were asked to identify the stimulated area. The mean error rate in point localization was 4.5%. (2) Non-task condition: laser pulses were delivered on the first intermetacarpal space, and the subject was asked to count the number of stimuli. The mean error rate in counting was 5...

  19. Auditory evoked potential: a proposal for further evaluation in children with learning disabilities. (United States)

    Frizzo, Ana C F


    The information presented in this paper demonstrates the author's experience in previews cross-sectional studies conducted in Brazil, in comparison with the current literature. Over the last 10 years, auditory evoked potential (AEP) has been used in children with learning disabilities. This method is critical to analyze the quality of the processing in time and indicates the specific neural demands and circuits of the sensorial and cognitive process in this clinical population. Some studies with children with dyslexia and learning disabilities were shown here to illustrate the use of AEP in this population.

  20. Effects of carnosine on the evoked potentials in hippocampal CA1 region

    Institute of Scientific and Technical Information of China (English)

    Zhou-yan FENG; Xiao-jing ZHENG; Jing WANG


    Objective: To directly examine the effects of carnosine on neuronal excitation and inhibition in rat hippocampus in vivo. Methods: Artificial cerebrospinal fluid with carnosine was directly administrated over the exposed rat hippocampus. The changes of neuron activity in the CA1 region of hippocampus were evaluated by orthodromically- and antidromically-evoked potentials, as well as paired-pulse stimulation paradigm. Results: In both orthodromic and antidromic response potentials, carnosine transformed population spikes (PSs) with single spike into epileptiform multiple spikes. In addition, similar to the effect of γ-aminobutyric acidA (GABAA) antagonist picrotoxin, carnosine decreased paired-pulse stimulating depression significantly.However, no significant change was observed in the spontaneous field potentials during the application of carnosine. Conclusion:The results indicate a disinhibition-induced excitation effect of carnosine on the CA1 pyramidal neurons. It provides important information against the application of carnosine as a potential anticonvulsant in clinical treatment.

  1. Control of humanoid robot via motion-onset visual evoked potentials. (United States)

    Li, Wei; Li, Mengfan; Zhao, Jing


    This paper investigates controlling humanoid robot behavior via motion-onset specific N200 potentials. In this study, N200 potentials are induced by moving a blue bar through robot images intuitively representing robot behaviors to be controlled with mind. We present the individual impact of each subject on N200 potentials and discuss how to deal with individuality to obtain a high accuracy. The study results document the off-line average accuracy of 93% for hitting targets across over five subjects, so we use this major component of the motion-onset visual evoked potential (mVEP) to code people's mental activities and to perform two types of on-line operation tasks: navigating a humanoid robot in an office environment with an obstacle and picking-up an object. We discuss the factors that affect the on-line control success rate and the total time for completing an on-line operation task.

  2. Motor evoked potentials enable differentiation between motor and sensory branches of peripheral nerves in animal experiments. (United States)

    Turkof, Edvin; Jurasch, Nikita; Knolle, Erik; Schwendenwein, Ilse; Habib, Danja; Unger, Ewald; Reichel, Martin; Losert, Udo


    Differentiation between motor and sensory fascicles is frequently necessary in reconstructive peripheral nerve surgery. The goal of this experimental study was to verify if centrally motor evoked potentials (MEP) could be implemented to differentiate sensory from motor fascicles, despite the well-known intermingling between nerve fascicles along their course to their distant periphery. This new procedure would enable surgeons to use MEP for placing nerve grafts at corresponding fascicles in the proximal and distal stumps without the need to use time-consuming staining. In ten sheep, both ulnar nerves were exposed at the terminal bifurcation between the last sensory and motor branch. Animals were then relaxed to avoid volume conduction. On central stimulation, the evoked nerve compound action potentials were simultaneously recorded from both terminal branches. In all cases, neurogenic motor nerve action potentials were recorded only from the terminal motor branch. The conclusion was that MEPs can be used for intraoperative differentiation between sensory and motor nerves. Further studies are necessary to develop this method for in situ measurements on intact nerve trunks.

  3. Fourier transformed steady-state flash evoked potentials for continuous monitoring of visual pathway function. (United States)

    Bergholz, R; Lehmann, T N; Fritz, G; Rüther, K


    Monitoring of somatosensory, motor and auditory pathway function by evoked potentials is routine in surgery placing these pathways at risk. However, visual pathway function remains yet inaccessible to a reliable monitoring. For this study, a method of continuous recordings was developed and tested. Steady-state visual evoked potentials were elicited by flash stimulation at 16 Hz and analysed using discrete Fourier transform. Amplitude and phase of the fundamental response were dynamically averaged and continuously plotted in a trend graph. The method was applied on awake individuals with normal vision and on patients undergoing neurosurgery. In most individuals it was possible to continuously record significant responses. Surprisingly, characteristic time-courses of amplitude and phase were observed in several subjects. These findings were attributed mainly to flicker-adaptation. During anesthesia, amplitude and signal-to-noise ratio were markedly smaller. Signal recognition was facilitated when potentials were recorded with a subdural electrode placed directly at the occipital pole. The anesthetic agent propofol had a major impact on the recordings.


    Institute of Scientific and Technical Information of China (English)

    YUAN Qing; MA Ruiling; JIN Rui


    Objective: To investigate the effect of acupuncture ("JIN's San Zhen") on infantile mental retardation (MR) .Methods: 44 cases of MR children were attributed to treatment group and 39 normal children to control group.P3(event-related potential) and brainstem evoked potentials were used as the indexes. Acupoints "Si-shen Zhen","Head Zhi San Zhen", "Hand Zhi San Zhen", "Foot Zhi San Zhen" were punctured with filiform needles, and stimulated by manipulating the needle once every 5 minutes with uniform reinforcing-reducing method. The treatment was conducted once daily, 6 times every week, with 4 months being a therapeutic course. Results: In comparison with normal children, the latency of P3 was longer and its amplitude lower in MR children. After 4 months' acupuncture treatment,the latency was shortened and the amplitude increased significantly in comparison with pre-treatment ( P<0.01,0.05). Results of the total inteiiigence quotient (TIQ) evaluation showed a 70.3% coincidence rate compared with improvement of P3. Conclusion: Changes of P3 and BAEP(brain auditory evoked potential) after acupuncture treatment may be related to the effect of "JIN's San Zhen" in bettering clinical symptoms and signs of MR infantile patients.

  5. Topographical Feature of Somatosensory Cortical Evoked Potential with Augmented Blocking of the Sensation Transmission along Meridians

    Institute of Scientific and Technical Information of China (English)

    许金森; 吴宝华; 胡翔龙; 杨广印; 韩丑萍


    Objective: To investigate the distribution features of somatosensory cortical evoked potential map with augmented blocking of the sensation transmission along meridians.Method: The EEG-4400 electro-encephalogram (EEG) and ND-1 brain electrical activity mapping were adopted on 11 volunteers with remarkable sensation transmission along meridians, showing that the sensation can transmit to head and face after stimulating the points below the knee joints. Also, special observation was made on accurate location of somatosensory cortical evoked potential map in 10 people without sensation transmission.Result: Observation on 11 volunteers with remarkable transmission along the Three Foot-yang Meridians showed that they presented with concurrent high potential reactions in somatosensory cortical lower limbs and face without blocking the augmented sensation transmission along the meridians; however, when mechanical pressure was exerted to block the sensation transmission,only one reaction in the lower limbs occurred in the somatosensory cortical evoked map and the other one in the face disappeared. Conclusion: Peripheral tissue evoking is the decisive factor for transmission along the meridians.%目的:探讨加压阻滞循经感传时皮层体觉诱发电位地形图的分布特点.方法:应用EEG 4400型脑电图仪和ND-1型脑地形图仪对11名循经感传显著的志愿者,刺激足三阳经膝关节以下穴位所引起的感传均可上行到头面部.另外,还对10名无感传者的皮层体觉诱发电位地形图的定位精确性进行了专门的观察.结果:对11名足三阳经循经感传显著的志愿者观察的结果表明,未加压阻滞循经感传时,在皮层体觉区的下肢和面部代表区同时出现了高电位反应.当以机械压迫阻滞感传,皮层体觉诱发电位地形图上只在下肢代表区出现一个反应,面部代表区的反应消失.结论:外周动因激发是产生循经感传现象的决定性因素.

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

    Directory of Open Access Journals (Sweden)

    Marino DiFranco

    Full Text Available BACKGROUND: 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. METHODS AND FINDINGS: 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. CONCLUSIONS: 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.

  7. Abnormality of cervical vestibular-evoked myogenic potentials and ocular vestibular-evoked myogenic potentials in patients with recurrent benign paroxysmal postitional vertigo. (United States)

    Lee, Jong Dae; Park, Moo Kyun; Lee, Byung Don; Lee, Tae Kyeong; Sung, Ki-Bum; Park, Ji Yun


    Our results show that cervical vestibular-evoked myogenic potential (cVEMP) or ocular VEMP (oVEMP) abnormalities in the recurrent benign paroxysmal positional vertigo (BPPV) group were significantly higher than those in the non-recurrent BPPV group. Therefore, we can infer that VEMP abnormality is one of risk factors for BPPV recurrence. This prospective study aimed to test the hypothesis that otolith dysfunction using the VEMP test is a cause of recurrence of BPPV. cVEMP and oVEMP tests using 500 Hz tone-burst stimuli were performed on 16 patients with recurrent BPPV between March 2010 and December 2011. Both VEMP tests were performed in 20 patients with non-recurrent BPPV. The differences in age, sex, and involved canal between the recurrent and non-recurrent BPPV groups were not significant. Abnormal cVEMP responses were detected in 5 of 16 (31.3%) subjects in the recurrent BPPV group and abnormal oVMEP responses were detected in 4 of 16 (25%) subjects in the recurrent BPPV group. When we defined VEMP abnormality as an abnormal cVEMP or abnormal oVEMP, VEMP abnormalities were detected in eight (50%) subjects in the recurrent BPPV group and in three (15%) subjects in the non-recurrent BPPV group; the difference between groups was significant.

  8. [Recording cervical and ocular vestibular evoked myogenic potentials: part 1: anatomy, physiology, methods and normal findings]. (United States)

    Walther, L E; Hörmann, K; Pfaar, O


    Vestibular evoked myogenic potentials (VEMP) have gained in clinical significance in recent years, now forming an integral part of neurootological examinations to establish the functional status of the otolith organs. They are sensitive to low-frequency acoustic stimuli. When stimulated, receptors in the sacculus and utriculous are activated. By means of reflexive connections, myogenic potentials can be recorded when the relevant muscles are tonically activated. The vestibulocolic (sacculocollic) reflex travels from the otolith organs over the central circuitry to the ipsilateral sternocleidomastoid muscle. Myogenic potentials can be recorded by means of cervical VEMP (cVEMP). The vestibuloocular reflex crosses contralaterally to the extraocular eye muscle. Ocular VEMP (oVEMP) are recorded periocularly, preferably from the inferior oblique muscle. Various stimulation methods are used including air conduction and bone conduction.

  9. Auditory evoked fields elicited by spectral, temporal, and spectral-temporal changes in human cerebral cortex

    Directory of Open Access Journals (Sweden)

    Hidehiko eOkamoto


    Full Text Available Natural sounds contain complex spectral components, which are temporally modulated as time-varying signals. Recent studies have suggested that the auditory system encodes spectral and temporal sound information differently. However, it remains unresolved how the human brain processes sounds containing both spectral and temporal changes. In the present study, we investigated human auditory evoked responses elicited by spectral, temporal, and spectral-temporal sound changes by means of magnetoencephalography (MEG. The auditory evoked responses elicited by the spectral-temporal change were very similar to those elicited by the spectral change, but those elicited by the temporal change were delayed by 30 – 50 ms and differed from the others in morphology. The results suggest that human brain responses corresponding to spectral sound changes precede those corresponding to temporal sound changes, even when the spectral and temporal changes occur simultaneously.

  10. Visual Evoked Potentials as a Readout of Cortical Function in Infants With Tuberous Sclerosis Complex. (United States)

    Varcin, Kandice J; Nelson, Charles A; Ko, Jordan; Sahin, Mustafa; Wu, Joyce Y; Jeste, Shafali Spurling


    Tuberous sclerosis complex is an autosomal dominant genetic disorder that confers a high risk for neurodevelopmental disorders, such as autism spectrum disorder and intellectual disability. Studies have demonstrated specific delays in visual reception skills that may predict the development of autism spectrum disorder and intellectual disability. Based on evidence for alterations in the retinogeniculate pathway in animal models of tuberous sclerosis complex, we asked whether children with tuberous sclerosis complex demonstrate alterations in early visual processing that may undermine the development of higher-level visual behaviors. Pattern-reversal visual evoked potentials were recorded in infants with tuberous sclerosis complex (n = 16) and typically developing infants (n = 18) at 12 months of age. Infants with tuberous sclerosis complex demonstrated remarkably intact visual evoked potentials even within the context of intellectual disability and epilepsy. Infants with tuberous sclerosis complex show intact visual cortical processing, suggesting that delays in visually mediated behaviors in tuberous sclerosis complex may not be rooted in early visual processing deficits.


    Institute of Scientific and Technical Information of China (English)

    白斌; 王坤正; 同志勤; 刘文科; 宋金辉; 袁国莲


    Objective To study the application value of cortical somatosensory evoked potential (CSEP) monitoring in child scoliosis surgery. Methods In surgeries of fifty-one children with scoliosis, the CSEP changes were continuously recorded by evoked potential instrument. The operations were performed under the guidance of CSEP monitoring. Results Before propping and reshaping, the latencies and amplitudes in all cases had no change. During propping and reshaping, the latencies of all cases were slowly elongated, but all less than 10 percent. The amplitudes in 15 cases dropped to 55 percent, but returned to 80 percent 3-8 minutes after stopping the operations or partially loosening the propped rods at once. The amplitude in one case suddenly dropped to 37 percent and returned to 54 percent half an hour after loosening the propped rods at once and recovered to the normal range one day after operation. All cases got ideal orthopedic results and no one had neurological complications post operation. Conclusion CSEP can accurately monitor the spinal injury and has a great value in preventing the spinal injury in child scoliosis surgery.

  12. Axono-cortical evoked potentials: A proof-of-concept study. (United States)

    Mandonnet, E; Dadoun, Y; Poisson, I; Madadaki, C; Froelich, S; Lozeron, P


    Awake surgery is currently considered the best method to tailor intraparenchymatous resections according to functional boundaries. However, the exact mechanisms by which electrical stimulation disturbs behavior remain largely unknown. In this case report, we describe a new method to explore the propagation toward cortical sites of a brief pulse applied to an eloquent white matter pathway. We present a patient, operated on in awake condition for removal of a cavernoma of the left ventral premotor cortex. At the end of the resection, the application of 60Hz stimulation in the white matter of the operculum induced anomia. Stimulating the same site at a frequency of 1Hz during 70seconds allowed to record responses on electrodes put over Broca's area and around the inferior part of central sulcus. Axono-cortical evoked potentials were then obtained by averaging unitary responses, time-locked to the stimulus. We then discuss the origin of these evoked axono-cortical potentials and the likely pathway connecting the stimulation site to the recorded cortical sites.

  13. [Evoked potentials and regional cerebral blood flow changes in conversion disorder: a case report and review]. (United States)

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


    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.

  14. Membrane Potential Dynamics of Spontaneous and Visually Evoked Gamma Activity in V1 of Awake Mice.

    Directory of Open Access Journals (Sweden)

    Quentin Perrenoud


    Full Text Available Cortical gamma activity (30-80 Hz is believed to play important functions in neural computation and arises from the interplay of parvalbumin-expressing interneurons (PV and pyramidal cells (PYRs. However, the subthreshold dynamics underlying its emergence in the cortex of awake animals remain unclear. Here, we characterized the intracellular dynamics of PVs and PYRs during spontaneous and visually evoked gamma activity in layers 2/3 of V1 of awake mice using targeted patch-clamp recordings and synchronous local field potentials (LFPs. Strong gamma activity patterned in short bouts (one to three cycles, occurred when PVs and PYRs were depolarizing and entrained their membrane potential dynamics regardless of the presence of visual stimulation. PV firing phase locked unconditionally to gamma activity. However, PYRs only phase locked to visually evoked gamma bouts. Taken together, our results indicate that gamma activity corresponds to short pulses of correlated background synaptic activity synchronizing the output of cortical neurons depending on external sensory drive.

  15. Measurement of motor evoked potentials following repetitive magnetic motor cortex stimulation during isoflurane or propofol anaesthesia. (United States)

    Rohde, V; Krombach, G A; Baumert, J H; Kreitschmann-Andermahr, I; Weinzierl, M; Gilsbach, J M


    Isoflurane and propofol reduce the recordability of compound muscle action potentials (CMAP) following single transcranial magnetic stimulation of the motor cortex (sTCMS). Repetition of the magnetic stimulus (repetitive transcranial magnetic stimulation, rTCMS) might allow the inhibition caused by anaesthesia with isoflurane or propofol to be overcome. We applied rTCMS (four stimuli; inter-stimulus intervals of 3, 4, 5 ms (333, 250, 200 Hz), output 2.5 Tesla) in 27 patients and recorded CMAP from the hypothenar and anterior tibial muscle. Anaesthesia was maintained with fentanyl 0.5-1 microg kg(-1) x h(-1) and either isoflurane 1.2% (10 patients) or propofol 5 mg kg(-1) x h(-1) with nitrous oxide 60% in oxygen (17 patients). No CMAP were detected during isoflurane anaesthesia. During propofol anaesthesia 333 Hz, four-pulse magnetic stimulation evoked CMAP in the hypothenar muscle in 75%, and in the anterior tibial muscle in 65% of the patients. Less response was obtained with 250 and 200 Hz stimulation. In most patients, rTCMS can overcome suppression of CMAP during propofol/nitrous oxide anaesthesia, but not during isoflurane anaesthesia. A train of four magnetic stimuli at a frequency of 333 Hz is most effective in evoking potentials from the upper and lower limb muscles. The authors conclude that rTCMS can be used for evaluation of the descending motor pathways during anaesthesia.

  16. TMS-induced motor evoked potentials in Wilson's disease: a systematic literature review. (United States)

    Bembenek, Jan P; Kurczych, Katarzyna; Członkowska, Anna


    Wilson's disease (WD) is a metabolic brain disease resulting from improper copper metabolism. Although pyramidal symptoms are rarely observed, subclinical injury is highly possible as copper accumulates in all brain structures. The usefulness of motor evoked potentials (MEPs) in pyramidal tracts damage evaluation still appears to be somehow equivocal. We searched for original papers assessing the value of transcranial magnetic stimulation elicited MEPs with respect to motor function of upper and lower extremity in WD. We searched PubMed for original papers evaluating use of MEPs in WD using key words: "motor evoked potentials Wilson's disease" and "transcranial magnetic stimulation Wilson's disease." We found six articles using the above key words. One additional article and one case report were found while viewing the references lists. Therefore, we included eight studies. Number of patients in studies was low and their clinical characteristic was variable. There were also differences in methodology. Abnormal MEPs were confirmed in 20-70% of study participants. MEPs were not recorded in 7.6-66.7% of patients. Four studies reported significantly increased cortical excitability (up to 70% of patients). Prolonged central motor conduction time was observed in four studies (30-100% of patients). One study reported absent or prolonged central motor latency in 66.7% of patients. Although MEPs may be abnormal in WD, this has not been thoroughly assessed. Hence, further studies are indispensable to evaluate MEPs' usefulness in assessing pyramidal tract damage in WD.

  17. Effects of remote cutaneous pain on trigeminal laser-evoked potentials in migraine patients. (United States)

    de Tommaso, Marina; Difruscolo, Olimpia; Sardaro, Michele; Libro, Giuseppe; Pecoraro, Carla; Serpino, Claudia; Lamberti, Paolo; Livrea, Paolo


    The present study aimed to evaluate heat pain thresholds and evoked potentials following CO(2) laser thermal stimulation (laser-evoked potentials, LEPs), during remote application of capsaicin, in migraine patients vs. non-migraine healthy controls. Twelve outpatients suffering from migraine without aura were compared with 10 healthy controls. The LEPs were recorded by 6 scalp electrodes, stimulating the dorsum of the right hand and the right supraorbital zone in basal condition, during the application of 3% capsaicin on the dorsum of the left hand and after capsaicin removal. In normal subjects, the laser pain and the N2-P2 vertex complex obtained by the hand and face stimulation were significantly reduced during remote capsaicin application, with respect to pre-and post-capsaicin conditions, while in migraine LEPs and laser pain were not significantly modified during remote painful stimulation. In migraine a defective brainstem inhibiting control may coexist with cognitive factors of focalised attention to facial pain, less sensitive to distraction by a second pain.

  18. Hearing outcomes after loss of brainstem auditory evoked potentials during microvascular decompression. (United States)

    Thirumala, Parthasarathy D; Krishnaiah, Balaji; Habeych, Miguel E; Balzer, Jeffrey R; Crammond, Donald J


    The primary aim of this paper is to study the pre-operative characteristics, intra-operative changes and post-operative hearing outcomes in patients after complete loss of wave V of the brainstem auditory evoked potential. We retrospectively analyzed the brainstem auditory evoked potential data of 94 patients who underwent microvascular decompression for hemifacial spasm at our institute. Patients were divided into two groups - those with and those without loss of wave V. The differences between the two groups and outcomes were assessed using t-test and chi-squared tests. In our study 23 (24%) patients out of 94 had a complete loss of wave V, with 11 (48%) patients experiencing transient loss and 12 (52%) patients experiencing permanent loss. The incidence of hearing loss in patients with no loss of wave V was 5.7% and 26% in patients who did experience wave V loss. The incidence of hearing change in patients with no loss of wave V was 12.6% and 30.43% in patients who did experience wave V loss. Loss of wave V during the procedure or at the end of procedure significantly increases the odds of hearing loss. Hearing change is a significant under-reported clinical condition after microvascular decompression in patients who have loss of wave V.

  19. Cervical and ocular vestibular evoked potentials in Machado-Joseph disease: Functional involvement of otolith pathways. (United States)

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


    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.

  20. Color vision in attention-deficit/hyperactivity disorder: a pilot visual evoked potential study. (United States)

    Kim, Soyeon; Banaschewski, Tobias; Tannock, Rosemary


    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.

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

    Directory of Open Access Journals (Sweden)

    Susana Camposano


    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.

  2. The role of Magnetic Resonance Imaging and Visual Evoked Potential in management of optic neuritis (United States)

    Al-Eajailat, Suha Mikail; Al-Madani Senior, Mousa Victor


    Introduction To report our experience in management of patients with optic neuritis. The effects of brain magnetic resonance imaging and visual evoked potential on management were investigated Methods This is a four years clinical trial that included patients presenting with first attack of optic neuritis older than 16 years with visual acuity of less than 6/60 and presentation within first week of illness. Brain magnetic resonance imaging and visual evoked potentials were done for all patients. Patients were classified into three groups. First group received placebo, second received oral steroids and third received intravenous and oral steroids. Primary outcome measure was improvement in visual acuity. Results A total number of 150 patients were enrolled in the study. Ocular pain was seen 127 patients Relative afferent pupillary defect in 142 patients and color vision impairment in 131 patients. Abnormal MRI findings were seen in 84 patients. Pattern reversal VEP was abnormal in all patients. Using oral or intravenous steroid resulted in faster recovery but did not affect the final visual outcome. Recurrence rate was higher in patients with multiple MRI lesions and diminished VEP amplitude. Using intravenous steroids decreased recurrence rate in patients with three and more MRI lesions and non recordable VEP response. Conclusion MRI and pattern reversal VEP are recommended to be done in all patients presenting with optic neuritis. We advise to give intravenous methyl prednisolone in patients with multiple MRI white matter lesions and non recordable VEP at presentation. PMID:25018804

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


    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.

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

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    Tihana Vešligaj


    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.

  5. Evoked potentials elicited by natural stimuli in the brain of unanesthetized crayfish. (United States)

    Hernández-Falcón, J; Serrato, J; Ramón, F


    Experiments were conducted to test some characteristics of vision by crayfish underwater and in air, and determine possible motion reactions elicited in response to naturalistic or quasi-ethological visual stimuli. Chronically implanted electrodes on the brain were used to record visually evoked potentials in response to moving bars at different speeds or to fish of different sizes. Electroretinograms were also recorded to detect when an object or a shadow appeared in the crayfish visual field. Ongoing brain activity is mild under basal conditions, but increases in RMS by approximately 6% in response to bar passage and 12 to 53% in response to fish motionless or swimming in front of the crayfish. When crayfish are free to move, fish swimming in front of them elicit intense brain activity, together with displacement toward them and an attempt to grab them. Visual evoked potentials are elicited by moving objects as small as 1 degree at a distance of 30 cm in air as well as underwater. None of the stimuli used induced evident behavioral responses under our conditions. We conclude that vision-action activities can be divided into (a) vision of irrelevant objects with short lasting electrical activity and no motion in response to it; (b) vision of mildly interesting objects with long-lasting electrical effects, but no motion in response to it; and (c) vision of relevant objects with appropriate motion reaction.


    Directory of Open Access Journals (Sweden)

    Parneet Kaur Bedi


    Full Text Available Background: Walking recovery is one of the main goals of patients after SCI. Walking is rated as primary goal and desire (together with bladder and bowel function irrespective of the level of lesion. Past literature terms walking as long-term outcome or as a primary means of mobility after SCI.In patients with SCI clinical and electrophysiological examinations are directed towards predicting functional recovery. Methods: A systematic research of all papers was made by the authors using the PRISMA 2009 guidelines. Using the various search engines 56 articles was found and 22 were selected for the present study. Out of these 17 were included for the final stage Result: Electrophysiological measures can provide information that complements clinical assessments such as the American Spinal Injury Association sensory and motor scores in the evaluation of outcomes after spinal cord injury (SCI. Conclusion: The authors review and summarize the literature regarding tests that are most relevant to the study of SCI recovery—in particular, motor evoked potentials and somatosensory evoked potentials (SSEPs. Both SSEP and MEP provide data clinically significant as a prognostic indicator.

  7. Single-trial evoked potentials study by combining wavelet denoising and principal component analysis methods. (United States)

    Zou, Ling; Zhang, Yingchun; Yang, Laurence T; Zhou, Renlai


    The authors have developed a new approach by combining the wavelet denoising and principal component analysis methods to reduce the number of required trials for efficient extraction of brain evoked-related potentials (ERPs). Evoked-related potentials were initially extracted using wavelet denoising to enhance the signal-to-noise ratio of raw EEG measurements. Principal components of ERPs accounting for 80% of the total variance were extracted as part of the subspace of the ERPs. Finally, the ERPs were reconstructed from the selected principal components. Computer simulation results showed that the combined approach provided estimations with higher signal-to-noise ratio and lower root mean squared error than each of them alone. The authors further tested this proposed approach in single-trial ERPs extraction during an emotional process and brain responses analysis to emotional stimuli. The experimental results also demonstrated the effectiveness of this combined approach in ERPs extraction and further supported the view that emotional stimuli are processed more intensely.

  8. Disappearance of click-evoked potentials on the neck of the guinea pig by pharmacological and surgical destruction of the peripheral vestibular afferent system. (United States)

    Matsuzaki, Masaki; Murofushi, Toshihisa


    In order to establish an animal model of acoustically evoked vestibulo-collic reflex, the so-called vestibular evoked myogenic potential in humans, potentials evoked by loud clicks on the neck of the guinea pig were recorded using subjects whose peripheral vestibular endorgans or vestibular afferents had been damaged. Four normal control guinea pigs, four guinea pigs that received an intramuscular injection of gentamicin for 20 days (90 mg/kg/day) and five guinea pigs whose vestibular nerves were surgically sectioned were used in this study. Under general anesthesia with an intraperitoneal injection of pentobarbital sodium (40 mg/kg), auditory brainstem responses (ABRs) were recorded. Then, potentials evoked by loud clicks on the pre-vertebral muscle at the level of the third cervical vertebral bone were recorded using silver ball electrodes. As a result, a distinctive negative peak (NP) with a latency of 6-8 ms was recorded in all animals in the control group. NP was not observed in the gentamicin-administered group while ABR was preserved. After sectioning the vestibular nerve, NP was abolished while ABR was preserved. From these results, NP could be of vestibular origin. These results are in agreement with a previous report of NP using subjects whose cochlea had been damaged pharmacologically.

  9. Are flash-evoked visual potentials useful for intraoperative monitoring of visual pathway function? (United States)

    Cedzich, C; Schramm, J; Fahlbusch, R


    Flash-evoked visual potentials (VEPs) recorded from the scalp were used in a series of 35 patients with tumors along the visual pathway: 3 orbital tumors, 25 perisellar tumors, 4 intraventricular tumors, and 3 occipital lesions. Preoperatively, various combinations of impaired visual fields and visual acuity were observed in over 90% of the patients. A postoperative decrease in visual function was observed in 3 cases. Of the 25 perisellar lesions, 13 were operated through a standard frontotemporal craniotomy and 12 were operated through a transnasal-transsphenoidal approach. VEPs were highly susceptible to volatile anesthetics, and there was a significant incidence of spontaneous latency increases and amplitude decreases in a large number of patients. There was an unacceptably high number of cases with significant VEP alteration occurring without concomitant visual function change. During trepanation or the transnasal approach, a reversible potential loss was observed in 11 patients, a profoundly altered wave form was seen in 8 cases, and a loss of single peaks was observed in 15 patients. During dissection of the tumor, a reversible potential loss or a potential with unidentifiable peaks was found in 25 cases; however, the VEPs recovered during closure or in the recovery room. There was no correlation between intraoperative VEP changes and the postoperative changes in visual function. In only 1 patient with an insignificant postoperative decrease in visual acuity from 0.4 to 0.3 was there a concomitant intraoperative potential loss. The major conclusion of our findings is that light-emitting diode flash-evoked VEPs demonstrate intraoperative changes that appear too early and too prominently to be caused solely by manipulation of the optic pathways.(ABSTRACT TRUNCATED AT 250 WORDS)

  10. On-line analysis of middle latency auditory evoked potentials (MLAEP) for monitoring depth of anaesthesia in laboratory rats

    DEFF Research Database (Denmark)

    Jensen, E W; Nygaard, M; Henneberg, S W


    using neuromuscular blocking agents (NMBA). A number of studies suggest that the Middle Latency Auditory Evoked Potentials (MLAEP) contain information about the state of consciousness in humans. The purpose of this study was to examine whether the AEP could serve as an indicator of depth of anaesthesia...... and decreasing gradually to a level between 50 and 20 as the rat was anaesthetised. Nine rats were anaesthetised and included in the study. Four doses of Hypnorm vet. and Dormicum were given as a total, each with 5 minutes interval. Clinical signs of the level of anaesthesia were observed simultaneously...... with the AEP. The results showed that in four rats DAI decreased to a level below 30 while anaesthetised. In the remaining five rats the AEP was only decreased to a level below 45. The results indicated that a simple dosing regimen based on weight was unable to give the same depth of anaesthesia in individual...

  11. Visual Evoked Potential Recording in a Rat Model of Experimental Optic Nerve Demyelination. (United States)

    You, Yuyi; Gupta, Vivek K; Chitranshi, Nitin; Reedman, Brittany; Klistorner, Alexander; Graham, Stuart L


    The visual evoked potential (VEP) recording is widely used in clinical practice to assess the severity of optic neuritis in its acute phase, and to monitor the disease course in the follow-up period. Changes in the VEP parameters closely correlate with pathological damage in the optic nerve. This protocol provides a detailed description about the rodent model of optic nerve microinjection, in which a partial demyelination lesion is produced in the optic nerve. VEP recording techniques are also discussed. Using skull implanted electrodes, we are able to acquire reproducible intra-session and between-session VEP traces. VEPs can be recorded on individual animals over a period of time to assess the functional changes in the optic nerve longitudinally. The optic nerve demyelination model, in conjunction with the VEP recording protocol, provides a tool to investigate the disease processes associated with demyelination and remyelination, and can potentially be employed to evaluate the effects of new remyelinating drugs or neuroprotective therapies.

  12. Sensitivity of the late positive potentials evoked by emotional pictures to neuroticism during the menstrual cycle. (United States)

    Zhang, Wenjuan; Zhou, Renlai; Wang, Qingguo; Zhao, Yan; Liu, Yanfeng


    The present event-related potentials (ERPs) study set out to investigate the effect of neuroticism on emotion evaluation during the menstrual cycle, with high and low neuroticism females viewing and evaluating valence and arousal of emotional pictures in the menstruation, late follicular and luteal phases. Behavioral results revealed no group or phase effect. ERPs data showed modulations of the menstrual cycle and neuroticism on the late positive potential (LPP), with the larger LPP (300-1000 ms post-stimulus) during the late follicular phase than that during the luteal phase and larger LPP (1000-3000 ms post-stimulus) in the high neuroticism group than that in the low neuroticism group. Furthermore, significant positive correlations between the LPP amplitudes and valence and arousal evaluations were observed mainly in the high neuroticism group. The present study provides electrophysiological evidences that the LPP evoked by emotional pictures are modulated both by the menstrual cycle and neuroticism.

  13. Effect of click-polarity on abnormality of intraoperatively monitored brainstem acoustic evoked potentials. (United States)

    Mokrusch, T; Schramm, J; Hochstetter, A


    The configuration of brainstem acoustic evoked potentials (BAEP) is influenced by the type of click stimuli used and may thus affect detectability of abnormalities. In a group of 19 patients with lesions in the posterior fossa BAEP were recorded pre- and intraoperatively. Repeat recordings were performed in each patient in two alternating series with rarefaction and condensation click stimuli. The findings demonstrated that intraoperative potential changes in latency and amplitude were different between the two stimulation modes, but did not vary significantly in their incidence. It was also not possible to predict from the preoperative BAEP which click polarity would demonstrate intraoperative changes more markedly, taking latency and amplitude as parameters. Two conclusions are drawn from this study: None of the two stimulation modes is superior in detecting intraoperative changes and therefore no recommendation can be made which click polarity to use. When working with only one click polarity it is recommended to use occasional control recordings with the other click polarity.

  14. A study on early detection of changes in visual pathway due to Diabetes mellitus by visual evoked potential

    Directory of Open Access Journals (Sweden)

    Rajesh Kumar, Sundararajan D, Rajvin Samuel Ponraj, M Srinivasan


    Full Text Available Electrical potentials have been recorded by surface Evoked Potentials namely the Somatosensory Evoked Potential, Auditory Brainstem Response and Visual Evoked Potential [VEP]. Visual conduction disturbance can be evaluated by these instruments. A mass response of cortical and possibly subcortical may be represented, visual areas to visual stimuli. Diabetic patients without a past history of cerebrovascular accidents diagnosed with Non- Proliferative Diabetic retinopathy[DR] with a best corrected visual acuity at least 6/9.This study was done to assess whether a delay in VEP latency observed in diagnosed type II DM patients could be ascribed to dysfunction of the retinal or post retinal structures or by both. It is to find out whether the VEP latencies are altered in diabetes or not, if altered and to correlate duration of the diabetes mellitus with visual evoked potential changes. Visual evoked potentials are useful as a non invasive investigatory method in establishing central nervous system neuropathy developing in diabetes. This study clearly shows that changes in VEP may be detected in diabetics before the onset of retinopathy. Future studies should be focused on evaluation of the time that elapses between the appearance of the first detectable pathologic electrophysiologic changes and the first ophthalmoscopically detectable retinal changes in patients with Diabetes Mellitus [DM].

  15. Vestibular-dependent inter-stimulus interval effects on sound evoked potentials of central origin. (United States)

    Todd, N P M; Govender, S; Colebatch, J G


    Todd et al. (2014ab) have recently demonstrated the presence of vestibular-dependent contributions to auditory evoked potentials (AEPs) when passing through the vestibular threshold as determined by vestibular evoked myogenic potentials (VEMPs), including a particular deflection labeled as an N42/P52 prior to the long-latency AEPs N1 and P2. In this paper we report the results of an experiment to determine the effect of inter-stimulus interval (ISI) and regularity on potentials recorded above and below VEMP threshold. Five healthy, right-handed subjects were recruited and evoked potentials were recorded to binaurally presented sound stimulation, above and below vestibular threshold, at seven stimulus rates with ISIs of 212, 300, 424, 600, 848, 1200 and 1696 ms. The inner five intervals, i.e. 300, 424, 600, 848, 1200 ms, were presented twice in both regular and irregular conditions. ANOVA on the global field power (GFP) were conducted for each of four waves, N42, P52, N1 and P2 with factors of intensity, ISI and regularity. Both N42 and P52 waves showed significant ANOVA effects of intensity but no other main effects or interactions. In contrast both N1 and P2 showed additional effects of ISI, as well as intensity, and evidence of non-linear interactions between ISI and intensity. A source analysis was carried out consistent with prior work suggesting that when above vestibular threshold, in addition to bilateral superior temporal cortex, ocular, cerebellar and cingulate sources are recruited. Further statistical analysis of the source currents indicated that the origin of the interactions with intensity may be the ISI sensitivity of the vestibular-dependent sources. This in turn may reflect a specific vestibular preference for stimulus rates associated with locomotion, i.e. rates close to 2 Hz, or ISIs close to 500 ms, where saccular afferents show increased gain and the corresponding reflexes are most sensitive.

  16. Electroencephalogram and evoked potential parameters examined in Chinese mild head injury patients for forensic medicine

    Institute of Scientific and Technical Information of China (English)

    Xi-Ping CHEN; Lu-Yang TAO; Andrew CN CHEN


    Objective To evaluate the usefulness of quantitative electroencephalogram (QEEG), flash visual evoked potential (F-VEP) and auditory brainstem responses (ABR) as indicators of general neurological status. Methods Comparison was conducted on healthy controls (N=30) and patients with brain concussion (N=60) within 24 h after traumatic brain injury. Follow-up study of patient group was completed with the same standard paradigm 3 months later. All participants were recorded in multi-modality related potential testing in both early and late concussion at the same clinical setting. Glasgow coma scale, CT scanning, and physical examinations of neuro-psychological function, optic and auditory nervous system were performed before electroencephalogram (EEG) and evoked potential (EEG-EP) testing. Any participants showed abnormal changes of clinical examinations were excluded from the study. Average power of frequency spectrum and power ratios were selected for QEEG testing, and latency and amplitude of F-VEP and ABR were recorded.Results Between patients and normal controls, the results indicated: (1) Highly significance (P < 0.01) in average power of α1 and power ratios of θ/α1, θ/α2, α1/α2 of EEG recording; (2) N70-P100 amplitude of F-VEP in significant difference at early brain concussion; and (3) apparent prolongation of Ⅰ~Ⅲ inter-peak latency of ABR appeared in some individuals at early stage after concussion. The follow-up study showed that some patients with concussion were also afflicted with characteristic changes of EEG components for both increments of α1 average power and θ/α2 power ratio after 3 months recording. Conclusion EEG testing has been shown to be more effective and sensitive than evoked potential tests alone on detecting functional state of patients with mild traumatic brain injury (MTBI). Increments of α1 average power and θ/α2 power ratio are the sensitive EEG parameters to determining early concussion and evaluating outcome of

  17. Exploring brainstem function in multiple sclerosis by combining brainstem reflexes, evoked potentials, clinical and MRI investigations. (United States)

    Magnano, Immacolata; Pes, Giovanni Mario; Pilurzi, Giovanna; Cabboi, Maria Paola; Ginatempo, Francesca; Giaconi, Elena; Tolu, Eusebio; Achene, Antonio; Salis, Antonio; Rothwell, John C; Conti, Maurizio; Deriu, Franca


    To investigate vestibulo-masseteric (VMR), acoustic-masseteric (AMR), vestibulo-collic (VCR) and trigemino-collic (TCR) reflexes in patients with multiple sclerosis (MS); to relate abnormalities of brainstem reflexes (BSRs) to multimodal evoked potentials (EPs), clinical and Magnetic Resonance Imaging (MRI) findings. Click-evoked VMR, AMR and VCR were recorded from active masseter and sternocleidomastoid muscles, respectively; TCR was recorded from active sternocleidomastoid muscles, following electrical stimulation of the infraorbital nerve. EPs and MRI were performed with standard techniques. Frequencies of abnormal BSRs were: VMR 62.1%, AMR 55.1%, VCR 25.9%, TCR 58.6%. Brainstem dysfunction was identified by these tests, combined into a four-reflex battery, in 86.9% of cases, by EPs in 82.7%, MRI in 71.7% and clinical examination in 37.7% of cases. The sensitivity of paired BSRs/EPs (93.3%) was significantly higher than combined MRI/clinical testing (70%) in patients with disease duration ⩽6.4years. BSR alterations significantly correlated with clinical, EP and MRI findings. The four-BSR battery effectively increases the performance of standard EPs in early detection of brainstem impairment, otherwise undetected by clinical examination and neuroimaging. Multiple BSR assessment usefully supplements conventional testing and monitoring of brainstem function in MS, especially in newly diagnosed patients. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  18. The effect of Jujuboside A on the evoked field potentials of granule cells in dentate gyrus

    Institute of Scientific and Technical Information of China (English)

    封洲燕; 郑筱祥


    Jujuboside A (JuA) is a main component of Jujubogenin extracted from the seeds of Ziziphus. The authors have not seen any report on JuA's direct effect on the neurons of the central nervous system. This study aimed to assess the effect of JuA on paired-pulse responses of dentate gyrus granule cells in urethane-anaesthetized rats, used intracerebroventricular (i.c.v.) JuA to mimic in vitro bath conditions in vivo. Paired-pulse stimuli with 80ms interpulse interval were used to stimulate the perforant pathway. Evoked responses were recorded in the dentate gyrus cell layer after i.c.v. administration of 0.9% normal saline or JuA. In the first responses, the slopes of excitatory postsynaptic potential (EPSP1) and the amplitudes of population spike (PS1) decreased significantly after administration of JuA while the PS1 latencies increased significantly. In the second responses, the EPSP2 slopes and PS2 latencies were changed similarly to those of the first ones, but PS2 amplitudes increased. The results showed that JuA may have some inhibitory effect on the granule cell excitability mediated by presynaptic mechanism but may have little effect on the excitability mediated by postsynaptic mechanism since the second evoked N-methyl-D-aspartic mediating paired-pulse facilitation is a postsynaptic mechanism.

  19. Nervus medianus evoked potentials and bispectral index during repeated transitions from consciousness to unconsciousness. (United States)

    Rundshagen, I; Mast, J; Mueller, N; Pragst, F; Spies, C; Cortina, K


    We investigated the relationship between median nerve somatosensory evoked potentials (SSEPs) and the bispectral index (BIS) during alternating periods of consciousness and propofol-induced unconsciousness. Loss of consciousness (LOC) was repetitively induced by bolus injections of propofol in 24 patients undergoing elective surgery in spinal anaesthesia. SSEP and the BIS were recorded during LOC and recovery of consciousness (ROC). The level of consciousness was clinically assessed by the observer's assessment of alertness/sedation scale. Propofol venous plasma concentrations were measured simultaneously. At LOC, all SSEPs latency components were prolonged (P or = 45 ms were smaller (P=0.008) and the BIS values were lower (Plevels during ROC. Regression analyses revealed that the SSEP components (five latencies and five amplitudes) explained 33% of the variance when predicting ROC; the BIS explained 12%. The combination of SSEP and BIS explained 37% of variance in this patient sample. Propofol venous plasma concentration was 1.2 (0.8) microg ml(-1) during LOC and 0.4 (0.5) microg ml(-1) during ROC. The present results indicate the usefulness of combining variables of the evoked and spontaneous EEG to measure different levels of consciousness, because the SSEP provide additional information beyond the BIS. Inter-individual variability of all the EEG variables limits their predictive potency of ROC after propofol infusion.

  20. 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)


    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.)

  1. On the independent component analysis of evoked potentials through single or few recording channels. (United States)

    Wang, Suogang; James, Christopher J


    In this work we propose a technique based on Independent Component Analysis (ICA), applied to single or two channel(s) recordings of electroencephalogram (EEG) brain signals. Standard (ensemble) ICA requires multiple channel recordings to work, however when single of few channels are required ensemble ICA cannot be readily applied. Single channel ICA (temporal ICA) can be performed by preprocessed the data using the method of delays. Few channels (space-time ICA) can be analysed in an extension to this method. These techniques are demonstrated on the P300 evoked potentials (EPs) of a brain-computer interfacing (BCI) word speller dataset. We furthermore show how it is possible to extract single trial evoked EPs (i.e. non-stimulus locked) within a little as 3 epochs and even on channels not over the event focus. Due to the poor SNR, as well as the presence of other artifacts, it is difficult to detect the P300 pattern on raw signal data. The results show that proposed algorithms are able to accurately and repeatedly extract the relevant information buried within noisy signals and to do so without the requirement of stimulus locked averages. These advantages are paramount for building a more reliable and robust system for use in real-world BCI--i.e. for use outside of the clinical laboratory.

  2. Electromotive Triggering and Single Sweep Analysis of Vestibular Evoked Myogenic Potentials (VEMPs). (United States)

    Hecker, Dietmar J; Lohscheller, Joerg; Schorn, Bianca; Koch, Klaus Peter; Schick, Bernhard; Dlugaiczyk, Julia


    Cervical (c) and ocular (o) vestibular evoked myogenic potentials (VEMPs) provide important tools for measuring otolith function. However, two major drawbacks of this method are encountered in clinical practice. First, recording of oVEMPs is compromised by small n10 amplitudes. Second, VEMP analysis is currently based on the averaging technique, resulting in a loss of information compared to single sweep analysis. Here, we: 1) developed a novel electromotive trigger mechanism for evoking VEMPs by bone-conducted vibration to the forehead and 2) established maximum entropy extraction of complex wavelet transforms for calculation of phase synchronization between VEMP single sweeps. Both c- and oVEMPs were recorded for n=10 healthy individuals. The oVEMP n10 amplitude was consistently higher (right: 24.84±9.71 μV; left: 27.40±14.55 μV) than previously described. Stable VEMP signals were reached after a smaller number of head taps (oVEMPs 6; cVEMPs 11) compared to current recommendations. Phase synchronization vectors and phase shift values were successfully determined for simulated and clinically recorded VEMPs, providing information about the impact of noise and phase jitter on the VEMP signal. Thus, the proposed method constitutes an easy-to-use approach for the fast detection and analysis of VEMPs in clinical practice.

  3. The effect of Jujuboside A on the evoked field potentials of Granule cells in dentate gyrus

    Institute of Scientific and Technical Information of China (English)

    封洲燕; 郑筱祥


    Jujuboside A( JuA) is a main component of Jujubogenin extracted from the seeds of Ziziphus.The authors have not seen report on JuA's direct effect on the neruons of the central nervous system.This study aimed to assess the effect of JuA on paried-pulse responses of dentate gyrus granule cells in urethaneanasesthetized rats,used intracerebroventricular(i.c.v.) JuA to mimic in vitro tath conditions in vivo.Pariedpulse stimuli with 80ms interpulse interval were used to stimulate the perforant pathway.Evoked responses first responses,the slopoes of excitatory postsynaptic potential(EPSP1) and the amplitudes of population spike (PS1) decreased significantly after administration of JuA while the PS1 latencies increased significantly.In the second responses.the EPSP2 slops and PS2 latencies were changed similarly to those of the first ones.but PS2 amplitudes increased.The results showed that JuA may have some inhibitory effect on the granule cell excitability mediated by presynaptic mechanism but may have little effect on the excitability mediated by postsynaptic mechanism since the second evoked N-methyl-D-aspartic mediating paired-pulse facilitation is a postsynaptic mechanism.

  4. The investigation of intercostal Somatosensory Evoked Potentials in senile patients with diabetes

    Institute of Scientific and Technical Information of China (English)

    Xu lanping; pan yonghua; lu weihong; wu yue; zhou lichun


    Objective: To explove intercostal Somatosensory evoked potcntials(ISEP)and MEP,SEP,BAEP,ECoG,VEP in the evaluation on senile patients with DM Methods:fffth-tvo neurologialy normal subjects and 35 senile patients with clinic ally definited Dm were used in this inrestigation to general intercostal SEPs were studied.It is that the stimulation site for the fifth,seventh and nineth intercostal nervcs is at the anterior axillary line, whereas the third intercostal nerve is excited just lateral to the stemum. Result:.ISEP latency date(X+2.5SD),ISEP side to side analysis, T test of ISEP in normal compared with diabetes, β cell function in 35 senile patients with DM were compared with plasma glucose,Ralation between ISEP and other multimodal evoked potential,the abnormal rate of ISEP26 case .Respectively comparison of ISEP between DM patients with healths controlsexcept LN3 RN3 LN9 t=0.147-1.57,,the others were t=2.3-7.3,p=0. 000-0.02.The ISEPresult were comparedwith FPG, PPG、 HbAlc,disease duration,insulin. C peptid r=0.243-0.905,p=0.0l-0.05.Conclusion:ISEP could evaluate sternum lesions affecting the thoracic nerve roots disease,but also might be help in judging peripheral nerve disease with DM early diagnosis and predict the course of the disease.

  5. A Preclinical Study of Laryngeal Motor-Evoked Potentials as a Marker Vagus Nerve Activation. (United States)

    Grimonprez, Annelies; Raedt, Robrecht; De Taeye, Leen; Larsen, Lars Emil; Delbeke, Jean; Boon, Paul; Vonck, Kristl


    Vagus nerve stimulation (VNS) is a treatment for refractory epilepsy and depression. Previous studies using invasive recording electrodes showed that VNS induces laryngeal motor-evoked potentials (LMEPs) through the co-activation of the recurrent laryngeal nerve and subsequent contractions of the laryngeal muscles. The present study investigates the feasibility of recording LMEPs in chronically VNS-implanted rats, using a minimally-invasive technique, to assess effective current delivery to the nerve and to determine optimal VNS output currents for vagal fiber activation. Three weeks after VNS electrode implantation, signals were recorded using an electromyography (EMG) electrode in the proximity of the laryngeal muscles and a reference electrode on the skull. The VNS output current was gradually ramped up from 0.1 to 1.0 mA in 0.1 mA steps. In 13/27 rats, typical LMEPs were recorded at low VNS output currents (median 0.3 mA, IQR 0.2-0.3 mA). In 11/27 rats, significantly higher output currents were required to evoke electrophysiological responses (median 0.7 mA, IQR 0.5-0.7 mA, p vagus nerve. Furthermore, our results suggest that low output currents are sufficient to activate vagal fibers.

  6. On shifting the blame to humanity: Historicist narratives regarding transgressors evoke compassion for the transgressor but disdain for humanity. (United States)

    Gill, Michael J; Getty, Phillip D


    People respond compassionately to transgressors whose immorality is rooted in an unfortunate life history. But, are reactions to such historicist narratives uniformly compassionate? We suggest not. We propose that historicist narratives also have a dark side. Specifically, they encourage blame shifting, in which negative evaluations of humanity arise hand in hand with compassion for the focal transgressor of the narrative. Indeed, historicist narratives portray the focal transgressor as victimized by multiple others, who destroy her goodness and remove her chance to flourish in life. This destruction of another's potential is itself a profound moral violation and thus activates far-reaching blame responses that feed a disdainful view of humanity. In three studies, we provide evidence that historicist narratives evoke compassion for one but disdain for the multitude. We show that the resulting disdain can diminish prosocial behaviour in unrelated contexts, that it is elicited by both experimenter-provided and participant-generated historicist narratives, and that it is created via blame shifting. Our findings question the assumption that proliferation of historicist thinking would necessarily contribute to creating a more compassionate, humane society.

  7. Is the movement-evoked potential mandatory for movement execution? A high-resolution EEG study in a deafferented patient. (United States)

    Kristeva, Rumyana; Chakarov, Vihren; Wagner, Michael; Schulte-Mönting, Jürgen; Hepp-Reymond, M-C


    During simple self-paced index finger flexion with and without visual feedback of the finger, we compared the movement-evoked potentials of the completely deafferented patient GL with those of 7 age-matched healthy subjects. EEG was recorded from 58 scalp positions, together with the electromyogram (EMG) from the first dorsal interosseous muscle and the movement trace. We analyzed the movement parameters and the contralateral movement-evoked potential and its source. The patient performed the voluntary movements almost as well as the controls in spite of her lack of sensory information from the periphery. In contrast, the movement-evoked potential was observed only in the controls and not in the patient. These findings clearly demonstrate that the movement-evoked potential reflects cutaneous and proprioceptive feedback from the moving part of the body. They also indicate that in absence of sensory peripheral input the motor control switches from an internal "sensory feedback-driven" to a "feedforward" mode. The role of the sensory feedback in updating the internal models and of the movement-evoked potential as a possible cortical correlate of motor awareness is discussed.

  8. Multichannel somato sensory evoked potential study demonstrated abnormalities in cervical cord function in brachial monomelic amyotrophy

    Directory of Open Access Journals (Sweden)

    Nalini A


    Full Text Available Background: Brachial monomelic amyotrophy (BMMA is known to affect the central cervical cord gray matter resulting in single upper limb atrophy and weakness. Settings and Design: Case series of BMMA patients who underwent somatosensory evoked potentials (SEP studies at a tertiary referral center. Aims: We proposed to record Multichannel Somatosensory Evoked Potentials (MCSSEP from median and ulnar nerves with neck in neutral and neck fully flexed position in 17 patients with classical BMMA seen over three years. Materials and Methods: Recordings were done from both median (MN and ulnar nerves (UN. N9, P9, N13, N20 potentials were recorded and amplitudes measured. SSEPs were performed in 22 age-matched healthy men. Amplitudes of cervical response were calculated by N13/P9 ratio and compared in both positions. Results: Among the controls N13 amplitude was always normal {MN: mean N13/P9 - 0.96 in neutral; 0.95 in flexed}{UN: mean N13/P9 - 0.82 in neutral; 0.83 in flexed}, and mean amplitudes did not reveal any difference in both conditions ( P >0.05. Among 17 patients N9, P9 and N20 responses were normal in neutral position. Flexion showed no change in latency or amplitude of N9 and N20 responses ( P -0.63 whereas the N13 response was abnormal in at least one tested nerve in the affected limb (MN: P < 0.01; UN: P < 0.01. During flexion, N13 response was abnormal in 14 (82% patients after MN stimulation and in all 17(100% after UN stimulation {MN: mean N13/P9 - 0.62 in neutral; 0.38 in flexed}{UN: mean N13/P9 - 0.55 in neutral; 0.31 in flexed}. Conclusion: MCSSEP in BMMA with neck flexion caused a significant reduction of the cervical N13 response indicating segmental cervical cord dysfunction.

  9. Neuromodulation of motor-evoked potentials during stepping in spinal rats. (United States)

    Gad, Parag; Lavrov, Igor; Shah, Prithvi; Zhong, Hui; Roy, Roland R; Edgerton, V Reggie; Gerasimenko, Yury


    The rat spinal cord isolated from supraspinal control via a complete low- to midthoracic spinal cord transection produces locomotor-like patterns in the hindlimbs when facilitated pharmacologically and/or by epidural electrical stimulation. To evaluate the role of epidural electrical stimulation in enabling motor control (eEmc) for locomotion and posture, we recorded potentials evoked by epidural spinal cord stimulation in selected hindlimb muscles during stepping and standing in adult spinal rats. We hypothesized that the temporal details of the phase-dependent modulation of these evoked potentials in selected hindlimb muscles while performing a motor task in the unanesthetized state would be predictive of the potential of the spinal circuitries to generate stepping. To test this hypothesis, we characterized soleus and tibialis anterior (TA) muscle responses as middle response (MR; 4-6 ms) or late responses (LRs; >7 ms) during stepping with eEmc. We then compared these responses to the stepping parameters with and without a serotoninergic agonist (quipazine) or a glycinergic blocker (strychnine). Quipazine inhibited the MRs induced by eEmc during nonweight-bearing standing but facilitated locomotion and increased the amplitude and number of LRs induced by eEmc during stepping. Strychnine facilitated stepping and reorganized the LRs pattern in the soleus. The LRs in the TA remained relatively stable at varying loads and speeds during locomotion, whereas the LRs in the soleus were strongly modulated by both of these variables. These data suggest that LRs facilitated electrically and/or pharmacologically are not time-locked to the stimulation pulse but are highly correlated to the stepping patterns of spinal rats.

  10. [Determination of irreversibility of clinical brain death. Electroencephalography and evoked potentials]. (United States)

    Buchner, H; Ferbert, A


    Principally, in the fourth update of the rules for the procedure to finally determine the irreversible cessation of function of the cerebrum, the cerebellum and the brainstem, the importance of an electroencephalogram (EEG), somatosensory evoked potentials (SEP) and brainstem auditory evoked potentials (BAEP) are confirmed. This paper presents the reliability and validity of the electrophysiological diagnosis, discusses the amendments in the fourth version of the guidelines and introduces the practical application, problems and sources of error.An EEG is the best established supplementary diagnostic method for determining the irreversibility of clinical brain death syndrome. It should be noted that residual brain activity can often persist for many hours after the onset of brain death syndrome, particularly in patients with primary brainstem lesions. The derivation and analysis of an EEG requires a high level of expertise to be able to safely distinguish artefacts from primary brain activity. The registration of EEGs to demonstrate the irreversibility of clinical brain death syndrome is extremely time consuming.The BAEPs can only be used to confirm the irreversibility of brain death syndrome in serial examinations or in the rare cases of a sustained wave I or sustained waves I and II. Very often, an investigation cannot be reliably performed because of existing sound conduction disturbances or failure of all potentials even before the onset of clinical brain death syndrome. This explains why BAEPs are only used in exceptional cases.The SEPs of the median nerve can be very reliably derived, are technically simple and with few sources of error. A serial investigation is not required and the time needed for examination is short. For these reasons SEPs are given preference over EEGs and BAEPs for establishing the irreversibility of clinical brain death syndrome.

  11. The effectiveness of FES-evoked EMG potentials to assess muscle force and fatigue in individuals with spinal cord injury. (United States)

    Ibitoye, Morufu Olusola; Estigoni, Eduardo H; Hamzaid, Nur Azah; Wahab, Ahmad Khairi Abdul; Davis, Glen M


    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 SCI) population.

  12. Modulation of trigeminal laser evoked potentials and laser silent periods by homotopical experimental pain. (United States)

    Romaniello, Antonietta; Arendt-Nielsen, Lars; Cruccu, Giorgio; Svensson, Peter


    Cutaneous laser stimulation activates predominantly the A-delta and C mechano-heat nociceptors. Applied to the perioral region, low intensity CO(2)-laser pulses evoke reproducible trigeminal cortical evoked potentials (LEPs). High intensity CO(2)-laser stimuli induce a reflex response in the contracted jaw-closing muscle, the so-called laser silent period (LSP). Both LEPs and LSP provide a useful tool to study the physiology of the trigeminal nociceptive system. In ten healthy subjects we recorded the subjective ratings of the perioral laser stimulation and the trigeminal LEPs and LSP before, during and after homotopic experimental tonic muscle (infusion of hypertonic saline into the masseter muscle) and tonic skin pain (topical application of capsaicin to the cheek). LEPs were recorded from the vertex at two stimulus intensities: low (1.1 x pain threshold, PTh) and high (1.5 x PTh). LSP from masseter and temporalis muscles were recorded bilaterally through surface electromyographic (EMG) electrodes. CO(2)-laser pulses were applied to the perioral region (V2/V3) on the painful and non-painful side. The amplitude of LEPs increased with higher stimulus intensities (P 0.20). The LSP in the masseter and temporalis muscles had similar onset-latency (80+/-5 ms), offset-latency (111+/-5 ms) and duration (31+/-4 ms). Experimental pain had no effect on the onset- and offset-latency (P>0.05). Experimental pain, whether from muscle or from skin, reduced the degree of suppression (PEMG curve (P< 0.005) of the LSP. The LSP was still suppressed during the post-pain recordings when the skin pain had disappeared (P<0.05). In all experiments experimental tonic pain decreased the subjective ratings of the perioral laser stimulation (P< 0.001). Experimental tonic pain, either from muscle or from skin, induced bilateral inhibitory effects on the trigeminal laser evoked potentials and brainstem reflex responses and on the subjective ratings of the laser pulses. These effects could be

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

    LENUS (Irish Health Repository)

    Iohom, G


    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.

  14. Phenothiazine effects on cerebral-evoked potentials and eye movements in acute schizophrenics. (United States)

    Rappaport, M; Hopkins, H K; Hall, K; Belleza, T


    An investigation was made of the effects of phenothiazine medication on the averaged visual-evoked potentials (AVEP) and on eye movements in hospitalized, young, acute schizophrenic patients. These results were compared with those of normal subjects who were not given medication. AVEP measures included maximum amplitude (Am), frequency of peaks (FOP'S), variability (V) and peak latencies for an early negative peak (N1) and a later positive peak (P6). Eye movement measures included percent of time looking at a stimulus slide, percent of time looking at a figure on the slide, the number of fixations and the percent of cells entered in which fixations occurred. For schizophrenics off and on phenothiazine medication, there were no consistently significant drug effects on any measure except frequency of peaks. Schizophrenics compared to normals had lower amplitudes, greater frequency of peaks, greater variability and lower eye movement scores.

  15. Reduced Quadriceps Motor-Evoked Potentials in an Individual with Unilateral Knee Osteoarthritis: A Case Report

    Directory of Open Access Journals (Sweden)

    Michael A. Hunt


    Full Text Available One male with unilateral osteoarthritis (OA of the knee underwent testing of corticospinal (CS excitability (as quantified from motor-evoked potentials (MEPs in the rectus femoris (RF using transcranial magnetic stimulation and quadriceps muscle strength. Baseline data indicated reduced MEP amplitudes in the RF of the affected limb compared to the unaffected limb. Increases in RF MEP amplitudes from both limbs were observed immediately following a 30-minute exercise session focusing on muscle strengthening. Following an 8-week muscle strengthening intervention, the participant exhibited increased MEP amplitudes and muscle strength in the affected limb. These findings suggest that alterations in peripheral muscle function found in patients with knee OA may have an origin centrally within the motor cortex and that interlimb differences may be evident in those with unilateral disease. These findings also suggest that CS excitability may be improved following a muscle strengthening intervention.

  16. Possible Long Term Effects of Chemical Warfare Using Visual Evoked Potentials

    Directory of Open Access Journals (Sweden)

    Abbas Riazi


    Full Text Available Some studies have already addressed the effects of occupational organic solvent exposure on the visually evoked potentials (VEPs. Visual system is an important target for Sulphur Mustard (SM toxicity. A number of Iranian victims of Sulphur Mustard (SM agent were apprehensive about the delay effect of SM on their vision and a possible delay effect of SM on their visual cortex. This investigation was performed on 34 individuals with a history of chemical exposure and a control group of 15 normal people. The Toennies electro-diagnosis device was used and its signals were saved as the latencies. The mean of N75, N140 and P100 of victims of chemical warfare (VCWs and control group indicated no significant results (P>0.05. The VCWs did not show any visual symptoms and there was no clear deficit in their VEPs.

  17. Neurotoxic effects of rubber factory environment. An auditory evoked potential study. (United States)

    Kumar, V; Tandon, O P


    The effects of rubber factory environment on functional integrity of auditory pathway have been studied in forty rubber factory workers using Brainstem Auditory Evoked Potentials (BAEPs) technique to detect early subclinical impairments. Results indicate that 47 percent of the workers showed abnormalities in prolongations of either peak latencies or interpeak latencies when compared with age and sex matched control subjects not exposed to rubber factory environment. The percent distribution of abnormalities (ears affected) were in the order of extrusion and calendering (75%) > vulcanising (41.66%) > mixing (28.57%) > loading and dispatch (23.07%) > tubing (18.75%) sections of the factory. This incidence of abnormalities may be attributed to solvents being used in these units of rubber factory. These findings suggest that rubber factory environment does affect auditory pathway in the brainstem.

  18. [Correlation of evoked potentials in the frontal cortex and hippocampus of cats in emotional stress]. (United States)

    Vanetsian, G L; Pavlova, I V


    Averaged auditory evoked potentials (AEPs) were recorded in symmetric points of the frontal cortex and dorsal hippocampus of cats performing acquired conditioned food-procuring reaction reinforced in 100% cases, urgent transition to 30%-reinforcement, and return to 100%-reinforcement. Emotional stress estimated by a heart rate rise developed during increased food motivation of a cat as well as during change in ordinary food-procuring stereotype. The emotional stress was accompanied by a high positive correlation of cortical and hippocampal AEPs. Decrease in the stress level led to a drop between AEP correlations and appearance of their negative values. In emotional stress, the interactions between the frontal cortex and dorsal hippocampus were asymmetric: right-side correlations were higher.

  19. Visually Evoked Potentials in a Patient with a Fyodorov-Zuev Keratoprosthesis

    Directory of Open Access Journals (Sweden)

    Roy Schwartz


    Full Text Available Purpose: To describe a visually evoked potential (VEP examination performed on a patient with a keratoprosthesis. Methods: We report the case of a 60-year-old patient with a Fyodorov-Zuev keratoprosthesis in the right eye complained of gradual visual deterioration in that eye. His past medical history consisted of failed corneal graft procedures due to corneal dystrophy and an Ahmed valve implantation due to secondary glaucoma. A clinical examination and an ultrasound demonstrated vitreal opacities. In order to assess the visual status, a flash VEP test was conducted. Results: VEP recorded from the right eye consisted of a broadened and poorly formed positive P1 wave, with a subnormal amplitude, but a normal latency. Consequently, the patient underwent a pars plana vitrectomy. Conclusion: This case demonstrates the viability of VEP exams in patients with keratoprostheses.


    Institute of Scientific and Technical Information of China (English)


    Objective To investigate the variation of auditory evoked potential P50 in first-episode schizo-phrenia. Methods P50 was recorded from 66 schizophrenics and 92 normal controls with American Brova instrument, and assessing their psychotic symptoms with PANSS. Results Compared with NC, schizophrenics showed sensory gating deficit, reflecting by increased S2/S1 ratio ( NC: 42 ± 21%, Sch :81 ± 40%, P < 0. 01 ). No significant correlation was found between PANSS score and the three markers for assessing the sensory gating, such as the S2/S1 ratio, S2-S1, and 100 (1-S2/S1) ( P >0. 05). Schizophrenics showed no differences with P50 markers between the 5 weeks and 12 weeks of treatment. Conclusion P50 might be biological trait marker of schizophrenia.

  1. 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;


    BACKGROUND: Neurophysiological evaluation of anorectal sensory function is hampered by a paucity of methods. Rapid balloon distension (RBD) has been introduced to describe the cerebral response to rectal distension, but it has not successfully been applied to the anal canal. METHODS: Nineteen...... 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...

  2. Evoked potentials elicited by stimulation of the lateral and anterior femoral cutaneous nerves in meralgia paresthetica. (United States)

    Cordato, Dennis J; Yiannikas, Con; Stroud, Jill; Halpern, Jean-Pierre; Schwartz, Raymond S; Akbunar, Mehmet; Cook, Melissa


    Seventy-five consecutive patients with clinical symptoms and signs of meralgia paresthetica underwent bilateral somatosensory evoked potential (SEP) studies involving stimulation of skin areas innervated by the lateral and anterior femoral cutaneous nerves of the thighs. The most common abnormality was an absolute lateral femoral cutaneous SEP latency > 40 ms in 35 patients (47%), followed by an absent response in 14 patients (19%), an absolute latency 50% compared with the contralateral response in 8 patients (11%), and an absolute latency 5 ms interside latency difference in 5 patients (7%). Anterior femoral cutaneous SEPs were of value in distinguishing meralgia paresthetica from a proximal lumbar radiculopathy in an additional 4 patients and confirming bilateral meralgia paresthetica in 10 patients.

  3. Augmented ocular vestibular evoked myogenic potentials to air-conducted sound in large vestibular aqueduct syndrome. (United States)

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


    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.

  4. Does athletic training in volleyball modulate the components of visual evoked potentials? A preliminary investigation. (United States)

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


    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.

  5. Cortical stimulation and tooth pulp evoked potentials in rats: a model of direct anti-nociception. (United States)

    Rusina, Robert; Barek, Stephane; Vaculin, Simon; Azérad, Jean; Rokyta, Richard


    While the effect of cortex stimulation on pain control is widely accepted, its physiological basis remains poorly understood. We chose an animal model of pain to study the influence of sensorimotor cortex stimulation on tooth pulp stimulation evoked potentials (TPEPs). Fifteen awake rats implanted with tooth pulp, cerebral cortex, and digastric muscle electrodes were divided into three groups, receiving 60 Hz, 40 Hz and no cortical stimulation, respectively. TPEPs were recorded before, one, three and five hours after continuous stimulation. We observed an inverse relationship between TPEP amplitude and latency with increasing tooth pulp stimulation. The amplitudes of the early components of TPEPs increased and their latency decreased with increasing tooth pulp stimulation intensity. Cortical stimulation decreased the amplitude of TPEPs; however, neither the latencies of TPEPs nor the jaw-opening reflex were changed after cortical stimulation. The decrease in amplitude of TPEPs after cortical stimulation may reflect its anti-nociceptive effect.

  6. Somatosensory evoked potentials assess the efficacy of circumcision for premature ejaculation. (United States)

    Xia, J-D; Jiang, H-S; Zhu, L-L; Zhang, Z; Chen, H; Dai, Y-T


    To assess the efficacy and mechanism of circumcision in the treatment of premature ejaculation (PE) with redundant prepuce, we enrolled a total of 81 PE patients who received circumcision. The patients' ejaculatory ability and sexual performances were evaluated before and after circumcision by using questionnaires (Intravaginal ejaculation latency time (IELT), Chinese Index of PE with 5 questions (CIPE-5) and International Index of Erectile function- 5 (IIEF-5)). Furthermore, somatosensory evoked potentials (SEPs) including dorsal nerve (DNSEP) and glans penis (GPSEP) of the patients were also measured. The mean IELTs of preoperation and post operation were 1.10±0.55 and 2.48±2.03 min, respectively (Pejaculation time improvement after circumcision is so small, and equal to placebo response, therefore it could not be interpreted as a therapeutic method in men with PE.

  7. 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


    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.

  8. Vestibular evoked myogenic potential: its use in Sudden Sensorineural Hearing Loss. (United States)

    Ledesma, Alleluia Lima Losno; Barreto, Monique Antunes de Souza Chelminski; Bahmad, Fayez


    Sudden sensorineural hearing loss (SHL) has uncertain origin and evolution. Vestibular evoked myogenic potential (VEMP) estimates of the vestibular pathway that can not be analyzed by the other entrance examinations, which can be helpful in diagnosing the extent of hearing damage in these patients. To investigate the clinical applicability of VEMP in patients with SHL. This is a systematic review. Searches were conducted in the databases PubMed/Medline, SciELO and LILACS. Data were tabulated. We found 45 articles, 15 of these made up the study by fitting either the inclusion factors. The objective of 60% of the studies was to determine whether the VEMP can be used as predictive hearing recovery Conclusion: VEMP may be useful as hearing recovery predictor in patients with sudden sensorineural hearing loss, justifying the implementation of such examination in this population.

  9. Value of visual evoked potential monitoring during trans-sphenoidal pituitary surgery. (United States)

    Chacko, A G; Babu, K S; Chandy, M J


    The visual outcome of 22 patients undergoing trans-sphenoidal excision of pituitary macroadenomas with intraoperative flash visual evoked potential (VEP) monitoring (Group A), was compared with a non-randomized group of 14 patients who had undergone similar operations without VEP monitoring (Group B). Tumour size, preoperative visual acuity, peripheral fields, and latencies and amplitudes of P1 and P2 were analysed to ascertain the best predictor of postoperative visual function. It was found that patients in Group A had a significantly greater improvement in field defects than those in Group B. There was no difference in postoperative improvement in visual acuity between the two groups. None of the variables analysed were good predictors of visual outcome.

  10. Evaluation of Visual Evoked Potential (VEP) in Patients With Chronic Obstructive Pulmonary Disease (COPD). (United States)

    Karthikkeyan, Kanmani; Padma, K; Rao, B Vishwanatha


    Chronic Obstructive Pulmonary Disease (COPD), a progressive and partially reversible disease, has drawn world-wide attention for its moderate prevalence rate and causing central and peripheral neuropathy. Considering its severity in causing visual pathway impairment, the present investigation was carried out to find out the functional integrity of the visual pathway through visual evoked potentials (VEP) and to determine the factors influencing the condition in COPD patients. A total of 30 COPD patients of both sexes, classified according to the severity of the disease based on spirometric indices, were subjected to VEP testing and series of wave forms were measured and compared with equal number of control subjects. The latency of N75 and P100 were prolonged (P VEP changes. Non-invasive procedure can possibly be utilized as a routine screening test for COPD patients for better medical care.

  11. Ageing effect on air-conducted ocular vestibular evoked myogenic potential

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    Kaushlendra Kumar


    Full Text Available One of the recent diagnostic tests to assess the function of otolithic organs is through vestibular evoked myogenic potential (VEMP testing. There are equivocal findings on effect of aging on ocular VEMP (oVEMP parameters with reference to latencies. Hence this study was taken up to investigate the age related changes in oVEMP parameters. This present study considered 30 participants in each age group i.e., young adults, middle-aged adults and older adults. oVEMP were recorded using insert earphone at 100dBnHL at 500hZ short duration tone burst. The results showed in older adult significant difference in response rate, latencies and amplitude as compared to young and middle adult. Hence age should be taken into consideration when interpreting oVEMP results.

  12. Human handling and presentation of a novel object evoke independent dimensions of fear in Japanese quail. (United States)

    Richard, S; Land, N; Saint-Dizier, H; Leterrier, C; Faure, J M


    Fear is a concept comprising several dimensions, but the nature of these dimensions and the relationships between them remain elusive. To investigate these dimensions in birds, we have used two genetic lines of quail divergently selected on tonic immobility duration, a behavioural index of fear. These two lines differ in their behavioural response to some, but not all, fear-inducing situations. In the present study, we investigated the contribution of human intervention in the differentiation between the two lines. To do this, fear responses towards a novel object were compared between lines in three conditions: (1) in the home cage without any human intervention, (2) in the home cage after human handling and (3) after placement in a novel environment by human handling. Fear behaviour differed between lines after human handling, with or without placement in a novel environment, but presentation of a novel object in the home cage without any human intervention induced similar fear responses in the two lines of quail. These results lead us to suggest that in quail, human intervention evokes a dimension of fear that differs from that evoked by sudden presentation of a novel object, in that these two dimensions may be selected independently. Copyright 2010 Elsevier B.V. All rights reserved.

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

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    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.

  14. Evoked potential abnormalities in multiple sclerosis: a cross sectional study on 25 patients

    Directory of Open Access Journals (Sweden)

    Harirchian MH


    Full Text Available "nBackground: Visual, brain stem auditory and somatosensory evoked potentials (EPs have been traditional paraclinical tests to evaluate the competency of sensory tracts in multiple sclerosis (MS patients. It seems that only one of these EPs could be sufficient, at least as a screening test. The objective of this paper is to evaluate the frequency of these three evoked potentials in definite MS patients. "nMethods: This descriptive cross-sectional study involved was 25 definite relapsing remitting MS patients who referred to our university hospital. Twenty five individuals from normal population without any neurologic, visual, auditory or sensory disorders have been evaluated as well to determine the standard values in our electrophysiology lab. Values more than mean+2.5SD for latencies and less than mean-2.5SD for amplitudes were considered as abnormal. "nResults: Fifteen (60%, 13 (52%, and 13 (52% had abnormal visual, auditory and somatosensory EPs respectively. The latency of P100 in visual EP (VEP had the most sensitivity among all of the parameters. It was determined that the possibility of abnormality in each of auditory and somatosensory EPs in the presence of normal VEP could be 30.8%. In other words 30.8% of patients with negative VEP could have a positive auditory brain stem or somatosensory EPs. "nConclusion: In our study, a VEP abnormality was more frequent than auditory brain stem and somatosensory EPs. Thus it is not logical to perform triple EP tests in all suspected MS patients, but auditory and somatosensory EPs could be considered in patients with normal VEP.

  15. Cerebral information processing in personality disorders: I. Intensity dependence of auditory evoked potentials. (United States)

    Wang, Wei; Wang, Yehan; Fu, Xianming; Liu, Jianhui; He, Chengsen; Dong, Yi; Livesley, W John; Jang, Kerry L


    Patients with personality disorders such as the histrionic type exaggerate their responses when receiving external social or environmental stimuli. We speculated that they might also show an augmenting pattern of the auditory evoked potential N1-P2 component in response to stimuli with increasing levels of intensity, a response pattern that is thought to be inversely correlated with cerebral serotonin (5-HT) activity. To test this hypothesis, we collected auditory evoked potentials in 191 patients with personality disorders (19 patients with the paranoid type, 12 schizoid, 14 schizotypal, 18 antisocial, 15 borderline, 13 histrionic, 17 narcissistic, 25 avoidant, 30 dependent and 28 obsessive-compulsive) and 26 healthy volunteers. Their personality traits were measured using the Dimensional Assessment of Personality Pathology-Basic Questionnaire (DAPP-BQ). Compared with healthy subjects and other patient groups, the histrionic group scored higher on the basic traits Affective Instability, Stimulus Seeking, Rejection and Narcissism, and on the higher traits Emotional Dysregulation and Dissocial, than the other groups, and the schizoid group scored lower on most of the DAPP-BQ basic and higher traits. In addition, the histrionic group showed steeper amplitude/stimulus intensity function (ASF) slopes at three midline scalp electrodes than the healthy controls or the other patient groups. The ASF slopes were not correlated with any DAPP-BQ traits in the total sample of 217 subjects. However, the DAPP-BQ basic trait Rejection was positively correlated with the ASF slopes at all three electrode sites in the histrionic group. The increased intensity dependence of the auditory N1-P2 component might indicate that cerebral 5-HT neuronal activity is, on average, weak in the histrionic patients.

  16. Rcpititative magnetic stimulation of gastrocnemius muscle evokes cerebral potentials in Duchcnnc muscular dystrophy

    Institute of Scientific and Technical Information of China (English)

    Cui Liying; Guan Yuzhou; Tang Xiaofu; Li Benhong


    OBJECTIVE: To study the function and mechanism of the ccrebral evoked potentials by repititative stimulation of calf muscle in Duchcnne mucular dystrophy (DMD) patients with obvious muscular dystrophy and pseudohyocrtrophy. METHODS: Wc measured cerebral cvoked potcntials by stimulation of calf muscles and SEP by stimulation of posterior tibial nerves at ankle in ten patients with DMD and ten normal controls matched with sex and age. The intensity of the magnetic stimulation was at 30% of maximal output (2.1 Tcsla) and the trcquency was I Hz. The low intensity of magnetic stimulation was just sufficient to produce a contraction of the muscle belly underncath the coil. Recording electrode was placed at 2 cm posterior to the Cz. referencc to Fpz. Thc latencics of N33. P38, N48 and P55 and amplitude (P38-N48) were recorded. SEP was recorded by routine methods. RESULTS: in normal subjects. thc amplitude of magnetic stimulation of calf muscle was 40% lower. and the latency of P38 was 2.9±2.1 ms longer compared with electrical stimulation of the posterior tibial nerves at ankle. In 6 patients. P38 latency from magnetic stimulation was remarkable prolonged (P<0.01). and in 4 patients. there no any response was found. SElP from electrical stimulation was normal in all patients. CONCLUSTION: DMD is an available model for the study of meclhanism of cerebral evoked potentials by magnetic stimulating muscles. Wc can coneludc that thc responses were produced by muscle input. The abnormal responses in patients may relate to decreased input of muscle by muscular dystrophy and pscudohypcrtrophy.

  17. Timing of evoked potentials forecasting the prognosis of severe stroke patients

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    Shu-ying XIAO


    Full Text Available Objective To investigate the best assessment time of short-latency somatosensory-evoked potential (SLSEP and brain stem auditory-evoked potential (BAEP in predicting the prognosis of patients with acute severe stroke. Methods Fifty-two patients who were diagnosed as supratentorial massive cerebral infarction or large-volume cerebral hemorrhage by brain CT and/or MRI examination with Glasgow Coma Scale (GCS ≤ 12 were selected as observation subjects. GCS, SLSEP and BAEP were recorded at 1-3 and 4-7 d after onset. Outcomes were examined 6 months later using the modified Rankin Scale (mRS. A mRS score of 0-4 was considered as favorable outcome while a score of 5-6 was considered as unfavorable. The correlation between different predictive indexes (GCS, SLSEP and BAEP and outcome (mRS was analyzed. The predictive accuracy was also analyzed. Results At 1-3 d after onset, there was no correlation between all the predictors and outcome (P > 0.05, for all. At 4-7 d after onset, SLSEP and BAEP were significantly correlated with mRS (P < 0.01, for all; C > 0.400. At 4-7 d after onset, the prognostic sensitivity of SLSEP and BAEP Ⅴ wave was 85.71%-97.62% ; prognostic specificity of BAEP was 80.00%-90.00%; positive predictive value of all predictors was 89.13%-96.88%; negative predictive value of SLSEP was 83.33%-85.71% ; total predictive accuracy of SLSEP was 88.46%-90.38%. The predictive accuracy of both SLSEP and BAEP achieved the clinical expectation, and the former is better than the latter. Conclusions SLSEP and BAEP have a high accuracy rate in predicting the unfavorable prognosis of patients with acute severe stroke 4-7 d after onset. DOI: 10.3969/j.issn.1672-6731.2015.12.004

  18. The Relationship between Parameters of Long-Latency Evoked Potentials in a Multisensory Design. (United States)

    Hernández, Oscar H; García-Martínez, Rolando; Monteón, Victor


    In previous papers, we have shown that parameters of the omitted stimulus potential (OSP), which occurs at the end of a train of sensory stimuli, strongly depend on the modality. A train of stimuli also produces long-latency evoked potentials (LLEP) at the beginning of the train. This study is an extension of the OSP research, and it tested the relationship between parameters (ie, rate of rise, amplitude, and peak latency) of the P2 waves when trains of auditory, visual, or somatosensory stimuli were applied. The dynamics of the first 3 potentials in the train, related to habituation, were also studied. Twenty healthy young college volunteers participated in the study. As in the OSP, the P2 was faster and higher for auditory than for visual or somatosensory stimuli. The first P2 was swifter and higher than the second and the third potentials. The strength of habituation depends on the sensory modality and the parameter used. All these findings support the view that many long-latency brain potentials could share neural mechanisms related to wave generation.

  19. Low-frequency rTMS inhibitory effects in the primary motor cortex: Insights from TMS-evoked potentials. (United States)

    Casula, Elias P; Tarantino, Vincenza; Basso, Demis; Arcara, Giorgio; Marino, Giuliana; Toffolo, Gianna Maria; Rothwell, John C; Bisiacchi, Patrizia S


    The neuromodulatory effects of repetitive transcranial magnetic stimulation (rTMS) have been mostly investigated by peripheral motor-evoked potentials (MEPs). New TMS-compatible EEG systems allow a direct investigation of the stimulation effects through the analysis of TMS-evoked potentials (TEPs). We investigated the effects of 1-Hz rTMS over the primary motor cortex (M1) of 15 healthy volunteers on TEP evoked by single pulse TMS over the same area. A second experiment in which rTMS was delivered over the primary visual cortex (V1) of 15 healthy volunteers was conducted to examine the spatial specificity of the effects. Single-pulse TMS evoked four main components: P30, N45, P60 and N100. M1-rTMS resulted in a significant decrease of MEP amplitude and in a significant increase of P60 and N100 amplitude. There was no effect after V1-rTMS. 1-Hz rTMS appears to increase the amount of inhibition following a TMS pulse, as demonstrated by the higher N100 and P60, which are thought to originate from GABAb-mediated inhibitory post-synaptic potentials. Our results confirm the reliability of the TMS-evoked N100 as a marker of cortical inhibition and provide insight into the neuromodulatory effects of 1-Hz rTMS. The present finding could be of relevance for therapeutic and diagnostic purposes.

  20. Endogenous attention signals evoked by threshold contrast detection in human superior colliculus. (United States)

    Katyal, Sucharit; Ress, David


    Human superior colliculus (SC) responds in a retinotopically selective manner when attention is deployed on a high-contrast visual stimulus using a discrimination task. To further elucidate the role of SC in endogenous visual attention, high-resolution fMRI was used to demonstrate that SC also exhibits a retinotopically selective response for covert attention in the absence of significant visual stimulation using a threshold-contrast detection task. SC neurons have a laminar organization according to their function, with visually responsive neurons present in the superficial layers and visuomotor neurons in the intermediate layers. The results show that the response evoked by the threshold-contrast detection task is significantly deeper than the response evoked by the high-contrast speed discrimination task, reflecting a functional dissociation of the attentional enhancement of visuomotor and visual neurons, respectively. Such a functional dissociation of attention within SC laminae provides a subcortical basis for the oculomotor theory of attention.

  1. Comparison of the effects of bicuculline and strychnine on brain stem auditory evoked potentials in the cat. (United States)

    Martin, M. R.; Penix, L. P.


    1 Experiments were performed to determine the effects of intravenously applied bicuculline and strychnine on the click-evoked brain stem auditory evoked potentials (BAEP) of cats. 2 The BAEP was not affected by bicuculline (0.5 mg/kg, i.v.) administration. Strychnine (0.2 mg/kg, i.v.) administration caused a significant increase in the amplitude of peak 4, which is thought to be produced by potentials in the superior olive, lateral lemniscus and inferior colliculus. 3 These results suggest that strychnine blocks glycinergic inhibitory inputs to these auditory structures. PMID:6824818

  2. Contact Heat Evoked Potentials (CHEPs) in Patients with Mild-Moderate Alzheimer's Disease and Matched Control-A Pilot Study

    DEFF Research Database (Denmark)

    Jensen-Dahm, Christina; Madsen, Caspar Skau; Waldemar, Gunhild


    OBJECTIVE: Clinical studies have found that patients with Alzheimer's disease report pain of less intensity and with a lower affective response, which has been thought to be due to altered pain processing. The authors wished to examine the cerebral processing of non-painful and painful stimuli...... using somatosensory evoked potentials and contact heat evoked potentials in patients with Alzheimer's disease and in healthy elderly controls. DESIGN: Case-control study SETTING AND SUBJECTS: Twenty outpatients with mild-moderate Alzheimer's disease and in 17 age- and gender-matched healthy controls...


    Institute of Scientific and Technical Information of China (English)


    Objective. To study the features and mechanism of the cerebral evoked potentials by repetitive stimulation of calf muscle in Duchenne muscular dystrophy (DMD) patients with obvious muscular dystrophy and psuedohypertrophy. Methods. Cerebral evoked potentials by stimulation of calf muscles and somatosensory evoked potentials (SEPs) by the stimulation of posterior tibial nerves at ankle were measured in 10 patients with DMD and 10 normal controls matched with gender and age. The intensity of the magnetic stimulation was at 30% of maximal output (2.1 Tesla, MagPro magnetic stimulator, Dantec) and the frequency was 1 Hz. The low intensity of magnetic stimulation was just sufficient to produce a contraction of the muscle belly underneath the coil. Recording electrode was placed at 2 cm posterior to the Cz, reference to Fpz. The latencies of N33, P38, N48 and P55 and amplitude (P38- N48) were recorded. SEPs were recorded by routine methods. Results. In normal subjects, the amplitudes of cerebral evoked potentials by magnetic stimulation of calf muscle was 40% lower than that by electrical stimulation of the posterior tibial nerves at ankle. The latency of P38 was 2.9± 2.1 ms longer compared with electrical stimulation of the posterior tibial nerves at ankle. In 6 patients, P38 latency from magnetic stimulation was remarkably prolonged (P<0.01), and in 4 patients, there was no remarkable response. SEPs evoked by electrical stimulation were normal in all of the patients.? Conclusion. DMD is an available model for the study of mechanism of cerebral evoked potentials by magnetic stimulating muscle. We can conclude that the responses from magnetic stimulation were produced by muscle input. The abnormal responses in patients may relate to decreased input of muscle by stimulating dystrophic and psedohypertrophic muscle.

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

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    Vijay Chandran


    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.

  5. Effect of higher frequency on the classification of steady-state visual evoked potentials (United States)

    Won, Dong-Ok; Hwang, Han-Jeong; Dähne, Sven; Müller, Klaus-Robert; Lee, Seong-Whan


    Objective. Most existing brain-computer interface (BCI) designs based on steady-state visual evoked potentials (SSVEPs) primarily use low frequency visual stimuli (e.g., evoke photosensitivity-based epileptic seizures, high frequency stimuli generally show less visual fatigue and no stimulus-related seizures. The fundamental objective of this study was to investigate the effect of stimulation frequency and duty-cycle on the usability of an SSVEP-based BCI system. Approach. We developed an SSVEP-based BCI speller using multiple LEDs flickering with low frequencies (6-14.9 Hz) with a duty-cycle of 50%, or higher frequencies (26-34.7 Hz) with duty-cycles of 50%, 60%, and 70%. The four different experimental conditions were tested with 26 subjects in order to investigate the impact of stimulation frequency and duty-cycle on performance and visual fatigue, and evaluated with a questionnaire survey. Resting state alpha powers were utilized to interpret our results from the neurophysiological point of view. Main results. The stimulation method employing higher frequencies not only showed less visual fatigue, but it also showed higher and more stable classification performance compared to that employing relatively lower frequencies. Different duty-cycles in the higher frequency stimulation conditions did not significantly affect visual fatigue, but a duty-cycle of 50% was a better choice with respect to performance. The performance of the higher frequency stimulation method was also less susceptible to resting state alpha powers, while that of the lower frequency stimulation method was negatively correlated with alpha powers. Significance. These results suggest that the use of higher frequency visual stimuli is more beneficial for performance improvement and stability as time passes when developing practical SSVEP-based BCI applications.

  6. Giant early components of somatosensory evoked potentials to tibial nerve stimulation in cortical myoclonus. (United States)

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


    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.

  7. Effects of overt and covert attention on the steady-state visual evoked potential. (United States)

    Walter, Sabrina; Quigley, Cliodhna; Andersen, Søren K; Mueller, Matthias M


    Flickering stimuli evoke an oscillatory brain response with the same frequency as the driving stimulus, the so-called steady-state visual evoked potential (SSVEP). SSVEPs are robust brain signals whose amplitudes are enhanced with attention and thus play a major role in the development and use of non-invasive Brain-Computer Interfaces (BCIs). We compared the modulation of SSVEP amplitudes when subjects directly gazed at a flickering array of static dots (overt attention) to when they covertly shifted attention to the dots keeping their eyes at central fixation. A discrimination task was performed at the attended location to ensure that subjects shifted attention as instructed. Horizontal eye movements (allowed in overt attention but to be avoided in covert attention) were monitored by the horizontal electrooculogram. Subjects' behavioural performance was significantly reduced in covert attention compared to overt attention. Correspondingly, attentional modulation of SSVEP amplitudes by overt attention was larger in magnitude than for covert attention. Overt attention also changed the topographical distribution of SSVEP amplitudes on the scalp. Stimuli elicited the largest amplitudes at central occipital electrodes when they were overtly attended and at contralateral parieto-occipital sites when they were covertly attended. Accordingly, source analysis revealed clear centrally located sources in early visual areas in overt attention, regardless of the attended visual hemifield. Taken together these results affirm that overt and covert attention have qualitatively and quantitatively different effects on SSVEP responses as well as on task performance. Moreover, our results suggest that navigating SSVEP-BCIs with overt attention is more reliable and highlight some of the challenges in developing BCIs for patients who have lost the ability to move their eyes.

  8. Differences in evoked potentials during the active processing of sound location and motion. (United States)

    Richter, Nicole; Schröger, Erich; Rübsamen, Rudolf


    Difference in the processing of motion and static sounds in the human cortex was studied by electroencephalography with subjects performing an active discrimination task. Sound bursts were presented in the acoustic free-field between 47° to the left and 47° to the right under three different stimulus conditions: (i) static, (ii) leftward motion, and (iii) rightward motion. In an active oddball design, subject was asked to detect target stimuli which were randomly embedded within a stream of frequently occurring non-target events (i.e. 'standards') and rare non-target stimuli (i.e. 'deviants'). The respective acoustic stimuli were presented in blocks with each stimulus type presented in either of three stimulus conditions: as target, as non-target, or as standard. The analysis focussed on the event related potentials evoked by the different stimulus types under the respective standard condition. Same as in previous studies, all three different acoustic stimuli elicited the obligatory P1/N1/P2 complex in the range of 50-200 ms. However, comparisons of ERPs elicited by static stimuli and both kinds of motion stimuli yielded differences as early as ~100 ms after stimulus-onset, i.e. at the level of the exogenous N1 and P2 components. Differences in signal amplitudes were also found in a time window 300-400 ms ('d300-400 ms' component in 'motion-minus-static' difference wave). For motion stimuli, the N1 amplitudes were larger over the hemisphere contralateral to the origin of motion, while for static stimuli N1 amplitudes over both hemispheres were in the same range. Contrary to the N1 component, the ERP in the 'd300-400 ms' time period showed stronger responses over the hemisphere contralateral to motion termination, with the static stimuli again yielding equal bilateral amplitudes. For the P2 component a motion-specific effect with larger signal amplitudes over the left hemisphere was found compared to static stimuli. The presently documented N1 components comply

  9. [Endogenous potentials evoked by acoustic stimulus in children with idiopathic headache--preliminary report]. (United States)

    Steczkowska-Klucznik, Małgorzata; Kroczka, Sławomir; Domaradzka, Ewa; Kaciński, Marek


    Endogenous evoked potentials (P300) are elicited by several stimuli, and are electrophysiological consequence of cognitive processing. Abnormalities have often been reported in dementive syndromes, demyelinating diseases, metabolic disorders, CNS tumors, phacomatoses, neuroinfections, attention deficit hyperactivity disorder and epilepsy. The role of this element of neurophysiological characteristics is debated in migraine, pato-genetically undefined, and other primary headaches. The aim of this research was to determine whether the parameters of endogenous responses to the transient auditory stimulation in children with migraine differ from parameters obtained from children with tension-type headache, and whether the results are different in children with primary headaches compared with headache-free controls. 56 patients, 27 girls and 29 boys aged from 10 to 18 years, recruited from the Department of Pediatric Neurology and Headache Outpatient Clinic of University Children's Hospital of Cracow were studied between 1.04.2004 and 31.08.2004. 21 children affected with migraine, 17 with aura, 4 without aura, and 15 children with frequent episodic tension-type headache (ETTH) were diagnosed according to IHS criteria, and compared with 20 sex- and age-matched headache-free controls. Endogenous evoked potentials P300 were performed in all children using auditory oddball paradigm, averaging 60 responses to stimuli different from the background activity. Responses were recorded using superficial electrodes placed on the frontal (Fz), middle (Cz) and parietal (Pz) region, while reference electrodes on the ear lobes. The procedure of average out of target and non target stimuli was repeated three times in each patient. The parameters of latency and amplitude of P300 were not significantly different between children with migraine, without aura and ETTH, and healthy controls. On the contrary, the amplitude of responses was lower in children with ETTH than in controls. However

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

    Directory of Open Access Journals (Sweden)

    Sheila Jacques Oppitz


    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.

  11. Effects of glutamate receptor agonists on the P13 auditory evoked potential and startle response in the rat

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    Christen eSimon


    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.

  12. High frequency bone conduction auditory evoked potentials in the guinea pig: Assessing cochlear injury after ossicular chain manipulation. (United States)

    Bergin, M J; Bird, P A; Vlajkovic, S M; Thorne, P R


    Permanent high frequency (>4 kHz) sensorineural hearing loss following middle ear surgery occurs in up to 25% of patients. The aetiology of this loss is poorly understood and may involve transmission of supra-physiological forces down the ossicular chain to the cochlea. Investigating the mechanisms of this injury using animal models is challenging, as evaluating cochlear function with evoked potentials is confounded when ossicular manipulation disrupts the normal air conduction (AC) pathway. Bone conduction (BC) using clinical bone vibrators in small animals is limited by poor transducer output at high frequencies sensitive to trauma. The objectives of the present study were firstly to evaluate a novel high frequency bone conduction transducer with evoked auditory potentials in a guinea pig model, and secondly to use this model to investigate the impact of middle ear surgical manipulation on cochlear function. We modified a magnetostrictive device as a high frequency BC transducer and evaluated its performance by comparison with a calibrated AC transducer at frequencies up to 32 kHz using the auditory brainstem response (ABR), compound action potential (CAP) and summating potential (SP). To mimic a middle ear traumatising stimulus, a rotating bur was brought in to contact with the incudomalleal complex and the effect on evoked cochlear potentials was observed. BC-evoked potentials followed the same input-output function pattern as AC potentials for all ABR frequencies. Deterioration in CAP and SP thresholds was observed after ossicular manipulation. It is possible to use high frequency BC to evoke responses from the injury sensitive basal region of the cochlea and so not rely on AC with the potential confounder of conductive hearing loss. Ongoing research explores how these findings evolve over time, and ways in which injury may be reduced and the cochlea protected during middle ear surgery.

  13. Are evoked potentials clinically useful in the study of patients with Chiari malformation Type 1? (United States)

    Moncho, Dulce; Poca, Maria A; Minoves, Teresa; Ferré, Alejandro; Cañas, Victoria; Sahuquillo, Juan


    OBJECTIVE In this study, the authors describe the brainstem auditory evoked potential (BAEP) and somatosensory evoked potential (SSEP) alterations found in a large cohort of patients with Chiari malformation Type 1 (CM-1), the relationship between the BAEPs/SSEPs and the clinical findings, the abnormalities in patients with associated syringomyelia, and the clinical and neuroradiological risk factors that are associated with abnormal evoked potentials (EPs). METHODS A prospectively collected database containing 545 patients with CM-1 was queried to search for patients satisfying the following criteria: 1) an age of at least 14 years, 2) neuroradiological criteria of CM-1, 3) no prior Chiari-related surgeries, and 4) preoperative EP studies conducted at the authors' institution. The 200 patients included in this cohort were classified into CM-0, CM-1, and CM-1.5 subtypes. Linear, planimetric, and angular measurements of the posterior fossa were conducted, as well as syringomyelia measurements. Two separate multiple logistic regression models were used, one to predict the covariates associated with abnormal BAEPs, and a second model to explore the variables associated with an abnormal SSEP. In these models, the BAEPs and SSEPs were dichotomized as being normal or abnormal. RESULTS Headaches were the main symptom in 70.5% of the patients, and Valsalva-induced headaches were most frequent in patients with CM-1 and CM-1.5 compared with patients with CM-0 (p = 0.031). BAEPs were abnormal in 38.5% of patients, and abnormal SSEPs were found in 43.5% of the entire cohort. Syringomyelia was most frequent in patients with CM-0 (64.3%) and CM-1 (51.1%) compared with those with CM-1.5 (34.7%; p = 0.03). Age (OR 1.03, 95% CI 1.00-1.06), the degree of tonsillar herniation (OR 1.08, 95% CI 1.01-1.16), and lower cranial nerve dysfunction (OR 3.99, 95% CI 1.29-14.01) had a statistically significant correlation with abnormal BAEPs. Only age (OR 1.07, 95% CI 1.04-1.10) and the degree

  14. Neurophysiological assessment of perceived image quality using steady-state visual evoked potentials (United States)

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


    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.

  15. Differential effects of endogenous lithium on neurobehavioural functioning: a study on auditory evoked potentials. (United States)

    Norra, Christine; Feilhauer, Johanna; Wiesmüller, Gerhard Andreas; Kunert, Hanns Jürgen


    Lithium occurs naturally in food and water. Low environmental concentrations in drinking water are associated with mental illnesses and behavioural offences, and at therapeutic dosages it is used to treat psychiatric (especially affective) disorders, partly by facilitating serotonergic (5-HT) neurotransmission. As little is known about the psychophysiological role of nutritional lithium in the general population, endogenous lithium concentrations were hypothesised to be associated with measurable effects on emotional liability and the loudness dependence (LD) that is proposed as one of the most valid indicators of 5-HT neurotransmission. Auditory evoked potentials of healthy volunteers [N=36] with high (>2.5 microg/l) or low (<1.5 microg/l) lithium serum concentrations were recorded. Emotional liability was assessed using the Brief Symptom Inventory (BSI). Low-lithium levels correlated with Somatisation while correlations between lithium and LD were not significant. Still, LD correlated positively with Paranoid Ideation, negatively with Anxiety and, in the high-lithium group, inversely with further aspects of emotional liability (Depression, Psychological Distress). In conclusion, the effects of low levels of endogenous lithium are associated with emotional liability, and high levels with some protective effects, although findings remain inconclusive regarding LD. Potential benefits of endogenous lithium on neurobehavioural functioning, especially in high-risk individuals, would have public health implications.

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

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    Natalia Gutiérrez Giraldo


    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.

  17. Alcohol Effects on the P2 component of Auditory Evoked Potentials

    Directory of Open Access Journals (Sweden)



    Full Text Available This is a second part of a research aimed to study the effects of alcohol on the electrophysiological processes in student volunteers. The first part showed that alcohol slowed the Omitted Stimulus Potential (OSP. This work studied the ethanol effects on the parameters (i.e. rate of rise, amplitude and peak latency of the P2 component of the evoked potentials (EPs yielded by trains of auditory stimuli. It is hypothesized here that if P2 and OSP waves share some common neural processes then alcohol should also affect these specific parameters. A dose of 0.8 g/kg of alcohol or a placebo (0 g/kg was administered to two groups of 15 young men who were tested before and again after treatment. The pre-post treatment change in each of the measurements was used to assess the treatment effects. The results showed that compared to placebo, alcohol slowed the P2 rise rate and reduced its amplitude, with no effects on peak latency. The rise rate is more sensitive to alcohol but more resistant to the adaptation process. Alcohol resembles the response inhibition model acting against the adaptation. The rise rate of the P2 and the OSP waves are affected by alcohol in a similar fashion, suggesting similar neural generative mechanisms.

  18. 3D graphics, virtual reality, and motion-onset visual evoked potentials in neurogaming. (United States)

    Beveridge, R; Wilson, S; Coyle, D


    A brain-computer interface (BCI) offers movement-free control of a computer application and is achieved by reading and translating the cortical activity of the brain into semantic control signals. Motion-onset visual evoked potentials (mVEP) are neural potentials employed in BCIs and occur when motion-related stimuli are attended visually. mVEP dynamics are correlated with the position and timing of the moving stimuli. To investigate the feasibility of utilizing the mVEP paradigm with video games of various graphical complexities including those of commercial quality, we conducted three studies over four separate sessions comparing the performance of classifying five mVEP responses with variations in graphical complexity and style, in-game distractions, and display parameters surrounding mVEP stimuli. To investigate the feasibility of utilizing contemporary presentation modalities in neurogaming, one of the studies compared mVEP classification performance when stimuli were presented using the oculus rift virtual reality headset. Results from 31 independent subjects were analyzed offline. The results show classification performances ranging up to 90% with variations in conditions in graphical complexity having limited effect on mVEP performance; thus, demonstrating the feasibility of using the mVEP paradigm within BCI-based neurogaming.

  19. Reliability of sensory nerve-conduction and somatosensory evoked potentials for diagnosis of meralgia paraesthetica. (United States)

    el-Tantawi, Gihan A Younis


    This work aims to determine reliability and diagnostic sensitivity of sensory nerve-conduction study and somatosensory evoked potentials (SEPs) for the assessment of meralgia paraesthetica (MP). Thirty-two patients with unilateral MP have been evaluated and compared to 30 control subjects. Sensory nerve-conduction study and SEPs (segmental and dermatomal) of the lateral femoral cutaneous nerve were used. Sensory nerve action potential (SNAP) was unobtainable in nine patients (28.1%) on either side, whereas SEPs were bilaterally recorded in all patients with significant difference between both methods as regards the ability to record a response (P<0.001). SNAP abnormalities were found in 15 out of 23 patients with recordable responses (65.2% sensitivity). Dermatomal SEP was abnormal in 26 of the 32 patients (81.3% sensitivity) and segmental SEP in 17 of the 32 patients (53.1% sensitivity). When the results of different techniques were considered together, sensitivity was found to have improved over that of either technique. Dermatomal SEP is considered superior to sensory nerve-conduction study for evaluation of MP. It is to be included in the routine evaluation of patients with MP. Segmental SEP is the least sensitive of these methods. Combining techniques would help better identification of patients with MP. Dermatomal SEP is to be included in routine evaluation of patients with MP. Combining techniques would help better identification of patients with MP.

  20. Proposal of a new criterion for electrodiagnosis of meralgia paresthetica by evoked potentials. (United States)

    Caramelli, Riccardo; Del Corso, Francesca; Schiavone, Vincenza; Fossi, Selvaggia; Cassardo, Annalisa; Pinto, Francesco; de Scisciolo, Giuseppe


    We examined 19 subjects with meralgia paresthetica (bilateral in three cases), recording bilateral somatosensory-evoked potentials (SSEPs) after stimulation of the tibial posterior nerve (TPN) and cutaneous stimulation in the region of the lateral femoral cutaneous nerve (LFCN). We calculated the difference between TPN SSEPs and LFCN SSEPs cortical potentials, identifying a temporal parameter that we termed D(SEP). We defined D(SEP) normal values in a control group. D(SEP) evaluation showed good sensitivity and specificity (85.7% and 82.4%, respectively; accuracy, 83.3%) in discriminating affected limbs from unaffected. The main advantage of this method is to disengage from the necessity of contralateral comparison of LFCN recordings, joined with a reduction of interindividual variability of LFCN SSEPs amplitude and latency that often causes a lower sensitivity of other methods. As an interesting consideration, D(SEP) evaluation appears to mark out a possible subclinical involvement of LFCN in the asymptomatic side of patients with meralgia paresthetica.

  1. The locus of color sensation: Cortical color loss and the chromatic visual evoked potential (United States)

    Crognale, Michael A.; Duncan, Chad S.; Shoenhard, Hannah; Peterson, Dwight J.; Berryhill, Marian E.


    Color losses of central origin (cerebral achromatopsia and dyschromatopsia) can result from cortical damage and are most commonly associated with stroke. Such cases have the potential to provide useful information regarding the loci of the generation of the percept of color. One available tool to examine this issue is the chromatic visual evoked potential (cVEP). The cVEP has been used successfully to objectively quantify losses in color vision capacity in both congenital and acquired deficiencies of retinal origin but has not yet been applied to cases of color losses of cortical origin. In addition, it is not known with certainty which cortical sites are responsible for the generation of the cVEP waveform components. Here we report psychophysical and electrophysiological examination of a patient with color deficits resulting from a bilateral cerebral infarct in the ventral occipitotemporal region. Although this patient demonstrated pronounced color losses of a general nature, the waveform of the cVEP remains unaffected. Contrast response functions of the cVEP are also normal for this patient. The results suggest that the percept of color arises after the origin of the cVEP and that normal activity in those areas that give rise to the characteristic negative wave of the cVEP are not sufficient to provide for the normal sensation of color. PMID:23986535

  2. Neurophysiological Effects of Meditation Based on Evoked and Event Related Potential Recordings (United States)

    Singh, Nilkamal; Telles, Shirley


    Evoked potentials (EPs) are a relatively noninvasive method to assess the integrity of sensory pathways. As the neural generators for most of the components are relatively well worked out, EPs have been used to understand the changes occurring during meditation. Event-related potentials (ERPs) yield useful information about the response to tasks, usually assessing attention. A brief review of the literature yielded eleven studies on EPs and seventeen on ERPs from 1978 to 2014. The EP studies covered short, mid, and long latency EPs, using both auditory and visual modalities. ERP studies reported the effects of meditation on tasks such as the auditory oddball paradigm, the attentional blink task, mismatched negativity, and affective picture viewing among others. Both EP and ERPs were recorded in several meditations detailed in the review. Maximum changes occurred in mid latency (auditory) EPs suggesting that maximum changes occur in the corresponding neural generators in the thalamus, thalamic radiations, and primary auditory cortical areas. ERP studies showed meditation can increase attention and enhance efficiency of brain resource allocation with greater emotional control. PMID:26137479

  3. Effects of acoustic noise on the auditory nerve compound action potentials evoked by electric pulse trains. (United States)

    Nourski, Kirill V; Abbas, Paul J; Miller, Charles A; Robinson, Barbara K; Jeng, Fuh-Cherng


    This study investigated the effects of acoustic noise on the auditory nerve compound action potentials in response to electric pulse trains. Subjects were adult guinea pigs, implanted with a minimally invasive electrode to preserve acoustic sensitivity. Electrically evoked compound action potentials (ECAP) were recorded from the auditory nerve trunk in response to electric pulse trains both during and after the presentation of acoustic white noise. Simultaneously presented acoustic noise produced a decrease in ECAP amplitude. The effect of the acoustic masker on the electric probe was greatest at the onset of the acoustic stimulus and it was followed by a partial recovery of the ECAP amplitude. Following cessation of the acoustic noise, ECAP amplitude recovered over a period of approximately 100-200 ms. The effects of the acoustic noise were more prominent at lower electric pulse rates (interpulse intervals of 3 ms and higher). At higher pulse rates, the ECAP adaptation to the electric pulse train alone was larger and the acoustic noise, when presented, produced little additional effect. The observed effects of noise on ECAP were the greatest at high electric stimulus levels and, for a particular electric stimulus level, at high acoustic noise levels.

  4. Hemisection spinal cord injury in rat: The value of intraoperative somatosensory evoked potential monitoring (United States)

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


    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 <0.001) and treadmill test (linear regression, R2 = 0.369, p = 0.016). Therefore, we propose intraoperative SSEP monitoring as a valuable tool to assess extent of lesion and reduce variability between animals in experimental studies of SCI. PMID:22960163

  5. Sensitivity of offset and onset cortical auditory evoked potentials to signals in noise. (United States)

    Baltzell, Lucas S; Billings, Curtis J


    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.


    Carbaryl is a widely used N-methyl carbamate pesticide that acts by inhibiting cholinesterases (ChE), which may lead to cholinergic toxicity. Flash evoked potentials (FEPs) are a neurophysiological response often used to detect central nervous system (CNS) changes following expos...

  7. Altered Automatic Face Processing in Individuals with High-Functioning Autism Spectrum Disorders: Evidence from Visual Evoked Potentials (United States)

    Fujita, Takako; Kamio, Yoko; Yamasaki, Takao; Yasumoto, Sawa; Hirose, Shinichi; Tobimatsu, Shozo


    Individuals with autism spectrum disorders (ASDs) have different automatic responses to faces than typically developing (TD) individuals. We recorded visual evoked potentials (VEPs) in 10 individuals with high-functioning ASD (HFASD) and 10 TD individuals. Visual stimuli consisted of upright and inverted faces (fearful and neutral) and objects…

  8. 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


    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...

  9. Stimulus-response characteristics of motor evoked potentials and silent periods in proximal and distal upper-extremity muscles.

    NARCIS (Netherlands)

    Kuijk, A.A. van; Anker, L.C.; Pasman, J.W.; Hendriks, J.C.M.; Elswijk, G.A.F. van; Geurts, A.C.H.


    OBJECTIVE: To compare stimulus-response characteristics of both motor evoked potentials (MEP) and silent periods (SP) induced by transcranial magnetic stimulation (TMS) in proximal and distal upper-extremity muscles. METHODS: Stimulus-response curves of MEPs and SPs were obtained from the biceps bra

  10. Stimulus-response characteristics of motor evoked potentials and silent periods in proximal and distal upper-extremity muscles.

    NARCIS (Netherlands)

    Kuijk, A.A. van; Anker, L.C.; Pasman, J.W.; Hendriks, J.C.M.; Elswijk, G.A.F. van; Geurts, A.C.H.


    OBJECTIVE: To compare stimulus-response characteristics of both motor evoked potentials (MEP) and silent periods (SP) induced by transcranial magnetic stimulation (TMS) in proximal and distal upper-extremity muscles. METHODS: Stimulus-response curves of MEPs and SPs were obtained from the biceps bra

  11. Auditory Evoked Potentials and Hand Preference in 6-Month-Old Infants: Possible Gender-Related Differences in Cerebral Organization. (United States)

    Shucard, Janet L.; Shucard, David W.


    Verbal and musical stimuli were presented to infants in a study of the relations of evoked potential left-right amplitude asymmetries to gender and hand preference. There was a relation between asymmetry and hand preference, and for girls, between asymmetry and stimulus condition. Results suggest a gender difference in cerebral hemisphere…

  12. Slow late component in conditioned stimulus-evoked potentials from the amygdala after fear conditioning in the rat

    NARCIS (Netherlands)

    Knippenberg, J.M.J.; Luijtelaar, E.L.J.M. van; Maes, J.H.R.


    Male Wistar rats were subjected to a differential Pavlovian fear conditioning procedure in which one of two tones (6 or 10 kHz) was followed by an electric shock (CS+) and the other was not (CS-). Before and after fear cnditioning, we recorded the evoked potentials elicited by CS+ and CS- from elect

  13. Comparison of bispectral index and composite auditory evoked potential index for monitoring depth of hypnosis in children

    NARCIS (Netherlands)

    H.J.B. van Oud-Alblas; J.W.B. Peters (Jeroen); T.G. de Leeuw (Tom); D. Tibboel (Dick); J. Klein (Jan); F. Weber (Frank)


    textabstractBACKGROUND: In pediatric patients, the Bispectral Index (BIS), derived from the electroencephalogram, and the composite A-Line autoregressive index (cAAI), derived from auditory evoked potentials and the electroencephalogram, have been used as measurements of depth of hypnosis during

  14. Comparison of bispectral index and composite auditory evoked potential index for monitoring depth of hypnosis in children

    NARCIS (Netherlands)

    H.J.B. van Oud-Alblas; J.W.B. Peters (Jeroen); T.G. de Leeuw (Tom); D. Tibboel (Dick); J. Klein (Jan); F. Weber (Frank)


    textabstractBACKGROUND: In pediatric patients, the Bispectral Index (BIS), derived from the electroencephalogram, and the composite A-Line autoregressive index (cAAI), derived from auditory evoked potentials and the electroencephalogram, have been used as measurements of depth of hypnosis during ane

  15. Influence of the power-spectrum of the pre-stimulus EEG on the consecutive Auditory Evoked Potential in rats.

    NARCIS (Netherlands)

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


    Evoked Potentials (EPs) are responses that appear in the EEG due to external stimulation. Findings indicate that changes in EPs can be related to changes in frequencies of the pre-stimulus EEG. Auditory EPs of rats (n=8) were measured in reaction to tone-pip stimuli (90 dB, 10.2 kHz, ISI 2s, n=1500)

  16. Multifocal visual evoked potential analysis of inflammatory or demyelinating optic neuritis. (United States)

    Fraser, Clare L; Klistorner, Alexander; Graham, Stuart L; Garrick, Raymond; Billson, Francis A; Grigg, John R


    To determine the sensitivity of multifocal visual evoked potentials (mVEP) in optic neuritis of an inflammatory or demyelinating nature. Cross-sectional study. Sixty-four patients participated who had a confirmed diagnosis of optic neuritis (ON) (past and acute). Based on the McDonald multiple sclerosis (MS) criteria, 25 patients (27 eyes with ON) were deemed to have isolated optic neuritis and thus not have MS (i.e., the not-MS group), and 19 patients (24 eyes with ON) had a diagnosis of MS (i.e., the MS group). The remaining 20 patients (25 eyes with ON) were at a high risk of MS, but diagnostic evaluation was equivocal, and thus were classified as the possible MS group. A control group of 20 normal patients was enrolled. The mVEP test was performed using the Accumap. All ON patients had recent magnetic resonance imaging scans of the brain and spinal cord. Multifocal visual evoked potentials amplitude and latency values were analyzed within each group and were compared with the normal controls. No abnormality was recorded on mVEP in the control group. Of all the ON eyes, 74 (97.3%) were abnormal on mVEP testing. Amplitude values were abnormal in 92.6% of not-MS eyes, 92.0% of possible MS eyes, and 100% of those with MS, and latency was abnormal in 33.3%, 76.0%, and 100%, respectively. There was a significant difference in the mVEP latency z-scores among all ON groups (P<0.01; Kruskal-Wallis test). Although distribution graphs of latency z-scores in the not-MS and MS groups had single peaks and were clearly separate from each other, the latency z-score distribution within the possible MS group in postacute patients was bimodal, with each peak corresponding to the distribution of the not-MS and MS group, respectively. The mVEP latency z-scores had a sensitivity and specificity of 100% in detecting patients with ON due to MS when compared with normal patients. The mVEP test is a sensitive and specific tool for detecting optic neuritis. There was a significant

  17. Reduced habituation to experimental pain in migraine patients: a CO(2) laser evoked potential study. (United States)

    Valeriani, M; de Tommaso, M; Restuccia, D; Le Pera, D; Guido, M; Iannetti, G D; Libro, G; Truini, A; Di Trapani, G; Puca, F; Tonali, P; Cruccu, G


    The habituation to sensory stimuli of different modalities is reduced in migraine patients. However, the habituation to pain has never been evaluated. Our aim was to assess the nociceptive pathway function and the habituation to experimental pain in patients with migraine. Scalp potentials were evoked by CO(2) laser stimulation (laser evoked potentials, LEPs) of the hand and facial skin in 24 patients with migraine without aura (MO), 19 patients with chronic tension-type headache (CTTH), and 28 control subjects (CS). The habituation was studied by measuring the changes of LEP amplitudes across three consecutive repetitions of 30 trials each (the repetitions lasted 5 min and were separated by 5-min intervals). The slope of the regression line between LEP amplitude and number of repetitions was taken as an index of habituation. The LEPs consisted of middle-latency, low-amplitude responses (N1, contralateral temporal region, and P1, frontal region) followed by a late, high-amplitude, negative-positive complex (N2/P2, vertex). The latency and amplitude of these responses were similar in both patients and controls. While CS and CTTH patients showed a significant habituation of the N2/P2 response, in MO patients this LEP component did not develop any habituation at all after face stimulation and showed a significantly lower habituation than in CS after hand stimulation. The habituation index of the vertex N2/P2 complex exceeded the normal limits in 13 out of the 24 MO patients and in none of the 19 CTTH patients (P<0.0001; Fisher's exact test). Moreover, while the N1-P1 amplitude showed a significant habituation in CS after hand stimulation, it did not change across repetitions in MO patients. In conclusion, no functional impairment of the nociceptive pathways, including the trigeminal pathways, was found in either MO or CTTH patients. But patients with migraine had a reduced habituation, which probably reflects an abnormal excitability of the cortical areas involved in

  18. Topography of synchronization of somatosensory evoked potentials elicited by stimulation of the sciatic nerve in rat

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    Xuefeng eQu


    Full Text Available Purpose: Traditionally, the topography of somatosensory evoked potentials (SEPs is generated based on amplitude and latency. However, this operation focuses on the physical morphology and field potential-power, so it suffers from difficulties in performing identification in an objective manner. In this study, measurement of the synchronization of SEPs is proposed as a method to explore brain functional networks as well as the plasticity after peripheral nerve injury. Method: SEPs elicited by unilateral sciatic nerve stimulation in twelve adult male Sprague-Dawley (SD rats in the normal group were compared with SEPs evoked after unilateral sciatic nerve hemisection in four peripheral nerve injured SD rats. The characterization of synchronized networks from SEPs was conducted using equal-time correlation, correlation matrix analysis, and comparison to randomized surrogate data. Eigenvalues of the correlation matrix were used to identify the clusters of functionally synchronized neuronal activity, and the participation index (PI was calculated to indicate the involvement of each channel in the cluster. The PI value at the knee point of the PI histogram was used as a threshold to demarcate the cortical boundary. Results: Ten out of the twelve normal rats showed only one synchronized brain network. The remaining two normal rats showed one strong and one weak network. In the peripheral nerve injured group, only one synchronized brain network was found in each rat. In the normal group, all network shapes appear regular and the network is largely contained in the posterior cortex. In the injured group, the network shapes appear irregular, the network extends anteriorly and posteriorly, and the network area is significantly larger. There are considerable individual variations in the shape and location of the network after peripheral nerve injury. Conclusion: The proposed method can detect functional brain networks. Compared to the results of the

  19. [A wireless smart home system based on brain-computer interface of steady state visual evoked potential]. (United States)

    Zhao, Li; Xing, Xiao; Guo, Xuhong; Liu, Zehua; He, Yang


    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.

  20. Changes of evoked potential in different hippocampal regions induced by electrostimulation at medial mamillary nucleus of rats

    Institute of Scientific and Technical Information of China (English)

    Xinxin Li; Lihong Shang; Liang Zhang; Fengzhi Cui


    BACKGROUND: Morphological data have shown that the most important afferent fibers of papillary body come from hippocampal structure.OBJECTIVE: To observe the changes of evoked potential in hippocampus and the significance after electrostimulation at medial mamillary nucleus.DESIGN: An observational control experiment.SETTING: Department of Physiology, Shenyang Medical College.MATERIALS: Twenty-three male or female Wistar rats, 3-4 months old, weighing 270-350 g, were provided by bhe animal room of Shenyang Medical College [the license number was scxk(Liao)2003-0016].METHODS: The Wistar rats were anaesthetized by intraperintoneal injection of 20% urethane (1 g/kg), tracheal intubation was also given. The self-made double-pole metal stimulating electrode with the point diameter of 1 mm was inserted into medial mamillary nucleus, the wanted hippocampal guidance spot was found within the rang of the hippocampal region at the same side of tee mamillary body range (CA1-CA4),inserted with same-core guidance electrode, a sole square-wave stimulation of wave wide 0.2 ms stimulated with electrodes at the applied intensity of 7-9 V, the evoked potential was induced through guidance electrodes, and then input to the ATAC-350 data-processing machine for memory showing wave processing, the memory recorded wave recording graph was separately drawn up by the X-Y recording instrument to observe the latency, time procedure and amplitude of the evoked potential in each hippocampal region of the rats and calculate the percentage of the evoked potential in each hippocampal region, Totally 78 guidance spots in hippocampus were recorded, including 30 positive reaction spots and 48 negative ones.MAIN OUTCOME MEASURES:① Latency,time procedure and amplitude of the evoked potentials in each hippocampal region of rats;② percentage of the evoked potentials in each hippocampal region;③ the wave shapes of the evoked potentials in each hippocampal region from different arrangement in the

  1. Auditory Evoked Potentials with Different Speech Stimuli: a Comparison and Standardization of Values

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    Didoné, Dayane Domeneghini


    Full Text Available Introduction Long Latency Auditory Evoked Potentials (LLAEP with speech sounds has been the subject of research, as these stimuli would be ideal to check individualś detection and discrimination. Objective The objective of this study is to compare and describe the values of latency and amplitude of cortical potentials for speech stimuli in adults with normal hearing. Methods The sample population included 30 normal hearing individuals aged between 18 and 32 years old with ontological disease and auditory processing. All participants underwent LLAEP search using pairs of speech stimuli (/ba/ x /ga/, /ba/ x /da/, and /ba/ x /di/. The authors studied the LLAEP using binaural stimuli at an intensity of 75dBNPS. In total, they used 300 stimuli were used (∼60 rare and 240 frequent to obtain the LLAEP. Individuals received guidance to count the rare stimuli. The authors analyzed latencies of potential P1, N1, P2, N2, and P300, as well as the ampleness of P300. Results The mean age of the group was approximately 23 years. The averages of cortical potentials vary according to different speech stimuli. The N2 latency was greater for /ba/ x /di/ and P300 latency was greater for /ba/ x /ga/. Considering the overall average amplitude, it ranged from 5.35 and 7.35uV for different speech stimuli. Conclusion It was possible to obtain the values of latency and amplitude for different speech stimuli. Furthermore, the N2 component showed higher latency with the / ba / x / di / stimulus and P300 for /ba/ x / ga /.

  2. Use of auditory evoked potentials for intra-operative awareness in anesthesia: a consciousness-based conceptual model. (United States)

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


    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

  3. Motor evoked potentials in standing and recumbent calves induced by magnetic stimulation at the foramen magnum. (United States)

    Rijckaert, J; Pardon, B; Verryken, K; Van Ham, L; van Loon, G; Deprez, P


    The aims of this study were to determine reference values for magnetic motor evoked potentials (mMEPs) in calves and the influence of position during examination (standing or lateral recumbency). Reference values were determined using 41 healthy Holstein Friesian bull calves aged 1-10 months; standing and lateral recumbency were examined in 11 calves. Maximal magnetic stimulation was performed at the level of the foramen magnum with a magnetic field of 4 T at the coil surface. In standing position, distinct, reproducible mMEPs were obtained in all calves. Onset latency (LAT) (mean ± standard deviation) was significantly shorter in the thoracic limbs (34.4 ± 3.1 ms) than in the pelvic limbs (44.6 ± 3.0 ms). Amplitude (AMPL) was significantly higher in the thoracic limbs (3.7 ± 1.7 mV) than in the pelvic limbs (3.3 ± 1.7 mV) and significantly increased with body length. Age, body weight, height at the withers and rectal temperature had no significant association with LAT or AMPL, and no differences between left and right were noted. In the lateral position, only 64% of the calves showed responses in the four limbs; in these calves, LAT (29.7 ± 4.7 ms) and AMPL (3.0 ± 1.8 mV) in the thoracic limbs were significantly different from AMPL (47.0 ± 7.4 ms) and LAT (2.1 ± 2.1 mV) in the pelvic limbs. In conclusion, mMEPs in limb muscles can be evoked in calves by stimulation at the level of the foramen magnum. mMEPs are more difficult to obtain in lateral recumbency than in standing calves. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Potentiation of K+-evoked catecholamine release in the cat adrenal gland treated with ouabain. (United States)

    Garcia, A. G.; Garcia-Lopez, E.; Horga, J. F.; Kirpekar, S. M.; Montiel, C.; Sanchez-Garcia, P.


    1 A vigorous catecholamine secretory response was evoked by small increments (2-10 mM) of the extracellular concentration of K+ ([K+])o) in cat adrenal glands treated with ouabain (10(-4) M), and perfused with Krebs-bicarbonate solution at room temperature. 2 The secretory response depends on [K+]o; increments of [K+]o as small as 2 mM for 2 min evoked a clear secretory response; at 10-17.7 mM K+, the maximal secretory response was observed. In normal glands, not treated with ouabain, no increase of the rate of catecholamine output was observed by raising [K+]o up to 17.7 mM for 2 min. 3 The K+ secretory response was time-dependent, requiring at least 1 min to be initiated; on continued exposure to 10 mM [K+]o, the enhanced response remained for at least 1 h. 4 In low [Na+]o, the K+-secretory response was unchanged. However, in 0-Ca2+, high-Mg2+ solutions, or in the presence of D600, an organic Ca2+ antagonist, it was abolished. 5 The K+-induced secretory response was not altered in the presence of tetrodoxin or tetraethylammonium. 6 It is concluded that ouabain potentiated the catecholamine secretory response to raised [K+]o by increasing the amount of Ca2+ available to the secretory machinery through (a) mobilization of an enhanced pool of membrane-bound Ca2+, (b) activation of membrane Ca2+ inward current; or (c) decrease of intracellular Ca2+ buffering systems. The activation by ouabain of a membrane Na+-Ca2+ exchange system is not involved in this K+-secretory response. It is suggested that the plasma membrane ATPase enzyme system, by changing the affinity of its Ca2+ binding sites, might control the availability of this cation to the secretory machinery and, therefore, modulate catecholamine secretion in the adrenal gland. PMID:7296168

  5. Evoked and event-related potentials in disorders of consciousness: A quantitative review. (United States)

    Kotchoubey, Boris


    Sixty-one publications about evoked and event-related potentials (EP and ERP, respectively) in patients with severe Disorders of Consciousness (DoC) were found and analyzed from a quantitative point of view. Most studies are strongly underpowered, resulting in very broad confidence intervals (CI). Results of such studies cannot be correctly interpreted, because, for example, CI>1 (in terms of Cohen's d) indicate that the real effect may be very strong, very weak, or even opposite to the reported effect. Furthermore, strong negative correlations were obtained between sample size and effect size, indicating a possible publication bias. These correlations characterized not only the total data set, but also each thematically selected subset. The minimal criteria of a strong study to EP/ERP in DoC are proposed: at least 25 patients in each patient group; as reliable diagnosis as possible; the complete report of all methodological details and all details of results (including negative results); and the use of appropriate methods of data analysis. Only three of the detected 60 studies (5%) satisfy these criteria. The limitations of the current approach are also discussed. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Effect of caffeine on cervical vestibular-evoked myogenic potential in healthy individuals

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    Ana Maria Almeida de Sousa


    Full Text Available INTRODUCTION: Caffeine is the most common psychoactive drug in use around the world and is found at different concentrations in a variety of common food items. Clinically, a strong association between caffeine consumption and diseases of the vestibular system has been established. Cervical vestibular-evoked myogenic potential (cVEMP is an electrophysiological test that is used to assess the sacculocollic pathway by measuring changes in the vestialibulocollic reflex. AIM: The present study aimed to evaluate the effect of an acute dose of caffeine on the vestibulocollic reflex by using cVEMP. METHOD: A prospective experimental study was performed in which healthy volunteers were submitted to the test before and after the intake of 420 mg of caffeine. The following parameters were compared: p13 and n23 latencies and p13-n23 amplitude. RESULT: No statistically significant difference was found in the test results before and after caffeine use. CONCLUSION: The vestibulocollic reflex is not altered by caffeine intake.

  7. Ketamine-Based Anesthetic Protocols and Evoked Potential Monitoring: A Risk/Benefit Overview (United States)

    Stoicea, Nicoleta; Versteeg, Gregory; Florescu, Diana; Joseph, Nicholas; Fiorda-Diaz, Juan; Navarrete, Víctor; Bergese, Sergio D.


    Since its discovery, ketamine, a non-competitive N-methyl D-aspartate (NMDA) receptor antagonist related to phencyclidine, has been linked to multiple adverse reactions sometimes described as “out of body” and “near death experiences,” including emergence phenomena, delusions, hallucinations, delirium, and confusion. Due to these effects, ketamine has been withdrawn from mainstream anesthetic use in adult patients. Evoked potentials (EPs) are utilized to monitor neural pathways during surgery, detect intraoperative stress or damage, detect and define the level of neural lesions, and define abnormalities. Unfortunately, many of the volatile anesthetics commonly used during spinal and neurologic procedures suppress EP amplitude and monitoring. Ketamine has been found in several preclinical and clinical studies to actually increase EP amplitude and thus has been used as an analgesic adjunct in procedures where EP monitoring is critical. Once the gap in our knowledge of ketamine's risks has been sufficiently addressed in animal models, informed clinical trials should be conducted in order to properly incorporate ketamine-based anesthetic regimens during EP-monitored neurosurgeries. PMID:26909017

  8. Development and evaluation of the piecewise Prony method for evoked potential analysis. (United States)

    Garoosi, V; Jansen, B H


    A new method is presented to decompose nonstationary signals into a summation of oscillatory components with time varying frequency, amplitude, and phase characteristics. This method, referred to as piecewise Prony method (PPM), is an improvement over the classical Prony method, which can only deal with signals containing components with fixed frequency, amplitude and phase, and monotonically increasing or decreasing rate of change. PPM allows the study of the temporal profile of post-stimulus signal changes in single-trial evoked potentials (EPs), which can lead to new insights in EP generation. We have evaluated this method on simulated data to test its limitations and capabilities, and also on single-trial EPs. The simulation experiments showed that the PPM can detect amplitude changes as small as 10%, rate changes as small as 10%, and 0.15 Hz of frequency changes. The capabilities of the PPM were demonstrated using single electroencephalogram/EP trials of flash visual EPs recorded from one normal subject. The trial-by-trial results confirmed that the stimulation drastically attenuates the alpha activity shortly after stimulus presentation, with the alpha activity returning about 0.5 s later. The PPM results also provided evidence that delta activity undergoes phase alignment following stimulus presentation.

  9. 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)


    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.)

  10. 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.

  11. A lower limb exoskeleton control system based on steady state visual evoked potentials (United States)

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


    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.

  12. Correlation of middle latency auditory evoked potentials and cerebral blood flow changes

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    Sugimoto, Seiichiro; Sugimoto, Akiko; Ohi, Takekazu; Matsukura, Shigeru; Watanabe, Katushi [Miyazaki Medical Coll., Kiyotake (Japan); Hoshi, Hiroaki


    The purpose of this study is to find the correlation between middle latency auditory evoked potentials (MLAEP) and sound activated single photon emission computed tomography (SPECT) studies. This study was performed on six normal right-handed volunteers with a mean age of 35.2{+-}7.6 years, using the split-dose technique. First, a SPECT study was performed on subjects in blinded, awake and silent states. After bilateral ears were stimulated with a click sound, MLAEP and a second SPECT study were performed. Subtraction of the first SPECT from the second SPECT revealed a statistically significant increase of cerebral blood flow (CBF) in the bilateral superior temporal region. Bilateral Na amplitudes of MLAEP had a statistically significant and good correlation with the percentages of CBF changes in the bilateral superior temporal region. The superior temporal cerebral blood flow activation can be expressed by electrophysiological activation. Moreover, correlation during the left Na components and left frontal and occipital lobe are discussed. (author)

  13. Cognitive processing effects on auditory event-related potentials and the evoked cardiac response. (United States)

    Lawrence, Carlie A; Barry, Robert J


    The phasic evoked cardiac response (ECR) produced by innocuous stimuli requiring cognitive processing may be described as the sum of two independent response components. An initial heart rate (HR) deceleration (ECR1), and a slightly later HR acceleration (ECR2), have been hypothesised to reflect stimulus registration and cognitive processing load, respectively. This study investigated the effects of processing load in the ECR and the event-related potential, in an attempt to find similarities between measures found important in the autonomic orienting reflex context and ERP literature. We examined the effects of cognitive load within-subjects, using a long inter-stimulus interval (ISI) ANS-style paradigm. Subjects (N=40) were presented with 30-35 80dB, 1000Hz tones with a variable long ISI (7-9s), and required to silently count, or allowed to ignore, the tone in two counterbalanced stimulus blocks. The ECR showed a significant effect of counting, allowing separation of the two ECR components by subtracting the NoCount from the Count condition. The auditory ERP showed the expected obligatory processing effects in the N1, and substantial effects of cognitive load in the late positive complex (LPC). These data offer support for ANS-CNS connections worth pursuing further in future work.

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

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


    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.

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

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


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

    DEFF Research Database (Denmark)

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


    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...

  17. Effect of visual stimulus locations on pattern-reversal visual evoked potential An epidural electrocorticogram study

    Institute of Scientific and Technical Information of China (English)

    Wensheng Hou; Weiwei Shi; Xiaolin Zheng; Na Liu; Zongxia Mou; Yingtao Jiang; Zhengqin Yin


    To explore the effect of the location of a visual stimulus on neural responses in the primary visual cortex (V1), a micro-electromechanical system-based microelectrode array with nine channels was implanted on the cerebral dura mater of V1 in adult cats. 2 Hz pattern reversal checkerboard stimuli were used to stimulate the four visual quadrants (i.e., upper left, upper right, lower left, and lower right fields). The results showed that there was a N75 component of the visual evoked potential around 50-80 ms after the onset of a checkerboard stimulus, and the onset of these N75 peaks varied with different stimulus locations. The checkerboard stimuli induced shorter latencies in the contralateral V1 than in the ipsilateral V1, while the checkerboard stimulus in the upper half visual field induced shorter latencies for N75. These results suggested that the pattern-reversal stimuli induced neural activities in V1 that can be recorded with multichannel microelectrodes, and more detailed temporal and spatial properties can be measured.

  18. Dose-dependent effect of nutritional sulfite intake on visual evoked potentials and lipid peroxidation. (United States)

    Ozturk, Nihal; Yargicoglu, Piraye; Derin, Narin; Akpinar, Deniz; Agar, Aysel; Aslan, Mutay


    The aim of this study was to clarify the dose-dependent effect of sulfite (SO₃²⁻) ingestion on brain and retina by means of electrophysiological and biochemical parameters. Fifty two male Wistar rats, aged 3 months, were randomized into four experimental groups of 13 rats as follows; control (C), sulfite treated groups (S(1); 10 mg/kg/day, S₂; 100mg/kg/day, S₃; 260 mg/kg/day). Control rats were administered distilled water, while the other three groups were given sodium metabisulfite (Na₂S₂O₅) of amounts mentioned above, via gavage for a period of 35 days. All components of visual evoked potential (VEP) were prolonged in S₂ and S₃ groups compared with S₁ and C groups. Plasma-S-sulfonate levels, which are an indicator of sulfur dioxide (SO₂) exposure, were increased in Na₂S₂O₅ treated groups in a dose-dependent manner. Furthermore, the significant increments in thiobarbituric acid reactive substances (TBARS) and 4-hydroxy-2-nonenal (4-HNE) levels occurred with increasing intake of Na₂S₂O₅. Though not significant, glutathione (GSH) and oxidized glutathione (GSSG) levels were observed to decrease with increasing doses of Na₂S₂O₅. In conclusion, Na₂S₂O₅ treatment in rats caused a dose-dependent increase in lipid peroxidation and all VEP latencies. The data indicate that lipid peroxidation could play an important role in sulfite toxicity.

  19. Quantifying interhemispheric symmetry of somatosensory evoked potentials with the intraclass correlation coefficient. (United States)

    van de Wassenberg, Wilma J G; van der Hoeven, Johannes H; Leenders, Klaus L; Maurits, Natasha M


    Although large intersubject variability is reported for cortical somatosensory evoked potentials (SEPs), variability between hemispheres within one subject is thought to be small. Therefore, interhemispheric comparison of SEP waveforms might be clinically useful to detect unilateral abnormalities in cortical sensory processing. We developed and evaluated a new technique to quantify interhemispheric SEP symmetry that uses a time interval including multiple SEP components, measures similarity of SEP waveforms between both hemispheres and results in high symmetry values even in the presence of small interhemispheric anatomic differences. Median nerve SEPs were recorded in 50 healthy subjects (20-70 years) using 128-channel EEG. Symmetry was quantified by the intraclass correlation coefficient and correlation coefficient between global field power of left and right median nerve SEPs. In 74% of subjects left-right intraclass correlation coefficient was higher than 0.60, implying high SEP hemispheric symmetry in terms of shape and amplitude. Left-right intraclass correlation coefficients lower than 0.60 were due to differences in amplitude, unilateral absence of peaks, or shape differences. We quantified SEP waveform interhemispheric symmetry and found it to be high in most healthy subjects. This technique may therefore be useful for detection of unilateral abnormalities in cortical sensory processing.

  20. Comparing the efficacy of excitatory transcranial stimulation methods measuring motor evoked potentials. (United States)

    Moliadze, Vera; Fritzsche, Georg; Antal, Andrea


    The common aim of transcranial stimulation methods is the induction or alterations of cortical excitability in a controlled way. Significant effects of each individual stimulation method have been published; however, conclusive direct comparisons of many of these methods are rare. The aim of the present study was to compare the efficacy of three widely applied stimulation methods inducing excitability enhancement in the motor cortex: 1 mA anodal transcranial direct current stimulation (atDCS), intermittent theta burst stimulation (iTBS), and 1 mA transcranial random noise stimulation (tRNS) within one subject group. The effect of each stimulation condition was quantified by evaluating motor-evoked-potential amplitudes (MEPs) in a fixed time sequence after stimulation. The analyses confirmed a significant enhancement of the M1 excitability caused by all three types of active stimulations compared to sham stimulation. There was no significant difference between the types of active stimulations, although the time course of the excitatory effects slightly differed. Among the stimulation methods, tRNS resulted in the strongest and atDCS significantly longest MEP increase compared to sham. Different time courses of the applied stimulation methods suggest different underlying mechanisms of action. Better understanding may be useful for better targeting of different transcranial stimulation techniques.

  1. Evaluation of neurodegeneration through visual evoked potentials in restless legs syndrome. (United States)

    Kısabay, Ayşın; Sarı, Ummu Serpil; Korkmaz, Tuğba; Dinçhorasan, Gönül; Yılmaz, Hikmet; Selçuki, Deniz


    Restless legs syndrome (RLS) is a disease characterized by some type of dysesthesia, an indescribable abnormal sensation in the extremities. Our objective was to determine whether the visual evoked potentials (VEP) can be used as a quantitative monitoring method to evaluate demyelination-remyelination and neurodegeneration in the patients with RLS. The present study was carried out prospectively. It was planned to determine normal or pathological conditions in the form of increased latency or decreased amplitude of VEP and to evaluate possible pathologies in the visual and retinal pathways at early stages and at months 3 and 6 of follow-up in the patients with RLS (with or without iron deficiency anemia), in those without RLS (at the time of diagnosis prior to any medical therapy) without any visual symptoms. It was observed that latency of VEP improved but didn't return to normal limits following treatment with dopamin agonists, iron, or combination of both and that there was no significant difference between the post-treatment data and those of the control group. These results in combination with the fact that the latencies and amplitudes didn't return to normal levels despite the 6-month-treatment but showed a progressive course with partial regeneration suggests that there was incomplete remyelination. It should be kept in mind that this syndrome is likely to be a part of neurodegenerative process.

  2. Stimulus Specificity of Brain-Computer Interfaces Based on Code Modulation Visual Evoked Potentials.

    Directory of Open Access Journals (Sweden)

    Qingguo Wei

    Full Text Available A brain-computer interface (BCI based on code modulated visual evoked potentials (c-VEP is among the fastest BCIs that have ever been reported, but it has not yet been given a thorough study. In this study, a pseudorandom binary M sequence and its time lag sequences are utilized for modulation of different stimuli and template matching is adopted as the method for target recognition. Five experiments were devised to investigate the effect of stimulus specificity on target recognition and we made an effort to find the optimal stimulus parameters for size, color and proximity of the stimuli, length of modulation sequence and its lag between two adjacent stimuli. By changing the values of these parameters and measuring classification accuracy of the c-VEP BCI, an optimal value of each parameter can be attained. Experimental results of ten subjects showed that stimulus size of visual angle 3.8°, white, spatial proximity of visual angle 4.8° center to center apart, modulation sequence of length 63 bits and the lag of 4 bits between adjacent stimuli yield individually superior performance. These findings provide a basis for determining stimulus presentation of a high-performance c-VEP based BCI system.

  3. Chromatic spatial contrast sensitivity estimated by visual evoked cortical potential and psychophysics. (United States)

    Barboni, M T S; Gomes, B D; Souza, G S; Rodrigues, A R; Ventura, D F; Silveira, L C L


    The purpose of the present study was to measure contrast sensitivity to equiluminant gratings using steady-state visual evoked cortical potential (ssVECP) and psychophysics. Six healthy volunteers were evaluated with ssVECPs and psychophysics. The visual stimuli were red-green or blue-yellow horizontal sinusoidal gratings, 5° × 5°, 34.3 cd/m2 mean luminance, presented at 6 Hz. Eight spatial frequencies from 0.2 to 8 cpd were used, each presented at 8 contrast levels. Contrast threshold was obtained by extrapolating second harmonic amplitude values to zero. Psychophysical contrast thresholds were measured using stimuli at 6 Hz and static presentation. Contrast sensitivity was calculated as the inverse function of the pooled cone contrast threshold. ssVECP and both psychophysical contrast sensitivity functions (CSFs) were low-pass functions for red-green gratings. For electrophysiology, the highest contrast sensitivity values were found at 0.4 cpd (1.95 ± 0.15). ssVECP CSF was similar to dynamic psychophysical CSF, while static CSF had higher values ranging from 0.4 to 6 cpd (P psychophysical methods (P psychophysical thresholds, mainly if the same temporal properties are applied to the stimulus. For blue-yellow CSF, correlation between electrophysiology and psychophysics was poor at high spatial frequency, possibly due to a greater effect of chromatic aberration on this kind of stimulus.

  4. Vestibular evoked myogenic potential eliciting in normal subjects: comparison of four different methods. (United States)

    Eleftheriadou, Anna; Deftereos, Spyros N; Zarikas, Vasilios; Panagopoulos, Grigoris; Korres, Stavros; Sfetsos, Sotirios; Karageorgiou, Klimentini L; Ferekidou, Elisa; Kandiloros, Dimitrios


    Vestibular evoked myogenic potential (VEMP) recording is a new method for testing the otolith receptors and vestibulospinal pathways. The aim of this study was to evaluate the characteristics of VEMP using four different techniques to find reasons to prefer one type of recording over the others. Twenty healthy persons, 10 males and 10 females with ages ranging from 20 to 57 years (mean age 41 years), were enrolled in this study. Eliciting of VEMPs by using monaural or binaural acoustic stimulation and unilateral or bilateral SCM contraction was evaluated; 105 dB NHL acoustic stimulation consisting of 145 dB rarefaction clicks was applied. Latencies of p13, n23, n34, p44 peaks; amplitudes p13-n23 and n34-p44; and interaural amplitude differences (IADs) were assessed. All four methods elicited constant and evident waveforms. The reliability coefficients of amplitudes were high for all four methods and for both waves. However, the higher scores of reliability appeared for the monaural-ipsilateral recording. The results indicated no statistically significant difference between the right and left sides for all four types of VEMP eliciting. No correlation was found between IAD13-23 and IAD34-44 for all four methods. Statistically significant differences were found only for n23 latency among the four methods. Although no evidence to reject or strongly favour a specific method was found, the monaural-ipsilateral recording was associated with some advantages.

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

    Directory of Open Access Journals (Sweden)

    Tsuyoshi Yoneda


    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.

  6. Correlation between caloric and ocular vestibular evoked myogenic potential test results. (United States)

    Huang, Chi-Hsuan; Wang, Shou-Jen; Young, Yi-Ho


    The ocular vestibular evoked myogenic potential (o-VEMP) test results correlate significantly with caloric test results for patients with acoustic neuroma (AN), but not for patients with Meniere's disease (MD), indicating that the o-VEMP test may replace the caloric test for evaluating the vestibular nerve from which the AN arises. Conversely, the caloric, o-VEMP, and cervical VEMP (c-VEMP) tests should be performed to map lesion sites in the vestibular labyrinth. This study performed caloric, o-VEMP, and c-VEMP tests on patients with central and peripheral vestibular disorders to investigate their relationships. In all, 66 patients comprising 16 with unilateral AN and 50 with unilateral definite MD were enrolled. All patients underwent caloric, o-VEMP, and c-VEMP tests. In the AN group, the caloric test identified canal paresis and caloric areflexia in 10 ears, while the o-VEMP and c-VEMP tests identified abnormal (absent or delayed) responses in 12 and 11 ears, respectively. A significant correlation existed between caloric and o-VEMP test results, but not between caloric and c-VEMP test results, or between o-VEMP and c-VEMP test results. For the MD group, abnormal caloric, o-VEMP, and c-VEMP test results were obtained for 24%, 44%, and 38% of hydropic ears, respectively. No correlation existed between any two test results.

  7. Ocular vestibular evoked myogenic potentials to air conduction (AC oVEMP): useful in clinical practice? (United States)

    Walther, L E; Rogowski, M; Hörmann, K; Schaaf, H; Löhler, J


    Cervical vestibular-evoked myogenic potential (cVEMP) and ocular VEMP (oVEMP) stimuli can be used to measure otolith function using air (AC) and bone conducted (BC) stimuli. Cervical VEMPs reflect saccular function and can be recorded using air conduction (AC), whereas oVEMPs reflect probably predominantly utricular function. Air- and bone-conducted vibration can be used, because AC oVEMP methodology seems to be fast and simple in clinical practice to measure otolith function. In this study we discuss the advantages and problems of AC oVEMP stimulation. AC oVEMP can be easily and quickly obtained within a few seconds. N10 (first negative peak) and p15 (first positive peak) latencies may be used as parameters for clinical interpretation but amplitude fluctuations are relatively large. For daily clinical use of VEMP visualization in a normogram seems feasible. Especially the AC oVEMP methodology (100 dB nHL, tone burst 500 Hz) is fast and efficient in clinical practice to measure otolith function, predominantly utricular function. Copyright © 2011 Polish Otolaryngology Society. Published by Elsevier Urban & Partner (Poland). All rights reserved.

  8. Development of ocular vestibular-evoked myogenic potentials in small children. (United States)

    Wang, Shou-Jen; Hsieh, Wu-Shiun; Young, Yi-Ho


    This study investigated the development of otolithic-ocular reflex in small children (ocular vestibular-evoked myogenic potential (oVEMP) test. Prospective study. Twenty full-term newborns (group A), 15 children aged 1 to 3 years (group B), and 15 children aged 4 to 13 years (group C) were enrolled in this study. All children underwent auditory brainstem response testing or audiometry, and the oVEMP test. All subjects had normal hearing. Typical biphasic oVEMP waveforms were not observed in the 20 newborns, but were present in six (40%) of 15 children aged 1 to 3 years and all (100%) children aged 4 to 13 years, exhibiting a significant difference. In group B, except for the nine children aged 12 to 24 months, the remaining six children, aged 25 to 47 months, had clear oVEMPs, with the mean nI latency and nI-pI amplitude resembling those in children aged 4 to 13 years, indicating that the otolithic-ocular reflex is mature in children aged >2 years. Despite the well-developed caloric and cervical VEMP responses in early life, oVEMPs are not present in newborns, but are present in children aged >2 years who can walk with a gait resembling an adult. Maturation of the otolithic-ocular reflex is important to balance control, which is necessary in small children for independent gait. Copyright © 2012 The American Laryngological, Rhinological, and Otological Society, Inc.

  9. An indicator of probable semicircular canal dehiscence: ocular vestibular evoked myogenic potentials to high frequencies. (United States)

    Manzari, Leonardo; Burgess, Ann M; McGarvie, Leigh A; Curthoys, Ian S


    The n10 component of the ocular vestibular evoked myogenic potential (oVEMP) to sound and vibration stimuli is a crossed response that has enhanced amplitude and decreased threshold in patients with CT-verified superior semicircular canal dehiscence (SSCD). However, demonstrating enhanced VEMP amplitude and reduced VEMP thresholds requires multiple trials and can be very time consuming and tiring for patients, so a specific indicator of probable SCD that is fast and not tiring would be preferred. Here we report a 1-trial indicator: that the oVEMP n10 in response to a very high frequency stimulus (4000 Hz), either air-conducted sound (ACS) or bone conducted vibration (BCV), is such a fast indicator of probable SCD. In 22 healthy subjects, oVEMP n10 at 4000 Hz was not detectable; however, in all 22 CT-verified SSCD patients tested, oVEMP n10 responses were clearly present to 4000 Hz to either ACS or BCV stimuli.

  10. Downbeat nystagmus: evidence for enhancement of utriculo-ocular pathways by ocular vestibular evoked myogenic potentials? (United States)

    Bremova, Tatiana; Glasauer, Stefan; Strupp, Michael


    Downbeat nystagmus (DBN) is caused by an impairment of Purkinje cells in the flocculus. The decreased cerebellar inhibitory input affects otolith pathways. Since ocular and cervical vestibular evoked myogenic potentials (o-/cVEMP) test the otoliths, the VEMP were measured in DBN patients and in controls. Sixteen patients with DBN, 14 cerebellar oculomotor disorder patients without DBN (COMD), and 16 healthy controls were examined with o-/cVEMP. Computational modeling was used to predict VEMP differences between groups. DBN patients had significantly higher oVEMP peak-to-peak (PP) amplitudes than COMD patients without DBN and controls. Cervical VEMP did not differ. The computational model of DBN predicted a twofold oVEMP increase for DBN patients. These findings suggest an enhancement of the utriculo-ocular response. The unchanged cVEMP indicate no effect on the otolith-cervical reflex in DBN. Computational modeling suggests that the utriculo-ocular enhancement is caused by an impaired vertical neural integrator resulting in the increased influence of utricular signals. This also explains the gravitational dependence of DBN.

  11. Pathological eye movements influence on the recordings of ocular vestibular-evoked myogenic potential. (United States)

    Yang, Ting-Hua; Chen, Hsin-Lin; Young, Yi-Ho


    This study investigated the influence of pathological eye movements on the recordings of ocular vestibulo-evoked myogenic potential (oVEMP). Ten patients with pathological eye movements of non-vestibular origin (nine congenital nystagmus and one opsoclonus) who had negative MRI result were assigned to Group A. Another 20 vestibular neuritis (VN) patients with spontaneous nystagmus were assigned to Group B. Both groups underwent audiometry, and caloric, oVEMP and cervical VEMP (cVEMP) tests. In Group A, the caloric, oVEMP and cVEMP tests showed 40%, 55% and 50% abnormalities, respectively. In Group B (VN), caloric, oVEMP and cVEMP tests revealed 100%, 80% and 45% abnormalities on the lesion ears, and 0%, 40% and 0% abnormalities on the healthy (opposite) ears, respectively. The 40% oVEMP abnormality on the healthy ears may be due to recording failure from the presence of spontaneous nystagmus, since five of five VN patients showed normal oVEMPs on the healthy ears, one year after presentation. Presence of pathological eye movements may affect the recordings of oVEMP. Thus, the oVEMP test is recommended to perform after acute vertiginous episode to exclude the influence of pathological eye movements on the oVEMP recordings.

  12. Correlation between subjective visual horizontal test and ocular vestibular-evoked myogenic potential test. (United States)

    Lin, Kuei-You; Young, Yi-Ho


    The static subjective visual horizontal (SVH) test correlates with the dynamic ocular vestibular-evoked myogenic potential (oVEMP) test in healthy and pathological ears, and further confirms that both tests may, at least in part, share the same utricular reflex pathway. This study correlated the SVH test results with those of the oVEMP and cervical VEMP (cVEMP) tests to investigate their relationships. Twenty healthy subjects underwent the SVH test at a view pattern angle of 30° or 70° horizontal tilt under various background distractions to establish the optimal stimulation mode for SVH test. Thereafter, 20 patients with unilateral Meniere's disease underwent the SVH test using the optimal mode. In addition, oVEMP and cVEMP tests were performed in all subjects. The preliminary study in 20 healthy subjects at a view pattern angle of 70° under counterclockwise square background distraction revealed that the mean deviation degree of the SVH test was -0.61 ± 1.17°. Based on the criteria, abnormal percentages of SVH in 20 Meniere's patients were 40%. All healthy subjects had normal oVEMPs and cVEMPs. In contrast, eight patients (40%) showed abnormal oVEMPs and nine (45%) revealed abnormal cVEMPs. The SVH test results correlated significantly with oVEMP results, but not with cVEMP results.

  13. Sudden Bilateral Hearing Loss After Cervical and Ocular Vestibular Evoked Myogenic Potentials. (United States)

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


    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.

  14. Ocular and cervical vestibular evoked myogenic potentials in multiple sclerosis patients. (United States)

    Gazioglu, Sibel; Boz, Cavit


    Vestibular evoked myogenic potentials (VEMPs) are thought to provide useful information about brainstem functions, as the neural pathways of both ocular and cervical VEMPs pass through the brainstem. The aim of this study was to investigate the clinical value of ocular and cervical VEMP tests in the evaluation of brainstem involvement in multiple sclerosis (MS) patients and to assess their relation with clinical and cranial MRI findings. Ocular and cervical VEMPs were recorded in 62 MS patients and 35 age and sex matched healthy volunteers. The latencies, amplitude asymmetry ratios of both VEMP responses and abnormality ratios (prolonged latencies and absent responses) were compared between the MS patients and the control group and among the groups of MS patients. oVEMP mean n1 and p1 latencies and cVEMP mean p13 latency were significantly prolonged in MS patients. Although the abnormality ratios of both VEMPs were higher in patients with brainstem clinical or MRI lesions, the correlation was not statistically significant. Both ocular and cervical VEMP latencies were significantly correlated with expanded disability status scale. Although there is no significant correlation with clinical or MRI findings, MS patients show high frequency of abnormality in VEMP tests, especially in oVEMP tests. VEMP tests may be useful as an adjunct test in the evaluation of brainstem dysfunction in MS patients. Copyright © 2012 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  15. Differentiating cerebellar and brainstem lesions with ocular vestibular-evoked myogenic potential test. (United States)

    Su, Chia-Hung; Young, Yi-Ho


    This study applied both ocular vestibular-evoked myogenic potential (oVEMP) and cervical VEMP (cVEMP) tests in patients with cerebellar disorders to determine whether VEMP test can differentiate between cerebellar and brainstem lesions. A total of 12 patients with cerebellar disorder, including extended cerebellar lesion (involving the brainstem) in 8 and localized cerebellar lesion (excluding the brainstem) in 4, were enrolled in this study. All patients underwent caloric, visual suppression, and oVEMP and cVEMP tests via bone-conducted vibration stimuli. The abnormal rates for the caloric, visual suppression, and oVEMP and cVEMP tests were 62, 83, 88 and 75% in patients with extended cerebellar lesion and 0, 25, 0 and 0% in those with localized cerebellar lesion, respectively. The rate of abnormal oVEMP results significantly differed between the two groups, but caloric, visual suppression and cVEMP test results did not differ. In another ten healthy subjects, characteristic parameters of oVEMPs obtained under light and dark conditions did not significantly differ. In conclusion, ocular VEMP test can differentiate between cerebellar and brainstem lesions. Abnormal oVEMPs in patients with cerebellar disorder may indicate adjacent brainstem involvement.

  16. The effect of increased intracranial pressure on vestibular evoked myogenic potentials in superior canal dehiscence syndrome. (United States)

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


    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.

  17. Spatiotemporal analysis of the cortical sources of the steady-state visual evoked potential. (United States)

    Di Russo, Francesco; Pitzalis, Sabrina; Aprile, Teresa; Spitoni, Grazia; Patria, Fabiana; Stella, Alessandra; Spinelli, Donatella; Hillyard, Steven A


    This study aimed to characterize the neural generators of the steady-state visual evoked potential (SSVEP) to repetitive, 6 Hz pattern-reversal stimulation. Multichannel scalp recordings of SSVEPs and dipole modeling techniques were combined with functional magnetic resonance imaging (fMRI) and retinotopic mapping in order to estimate the locations of the cortical sources giving rise to the SSVEP elicited by pattern reversal. The time-varying SSVEP scalp topography indicated contributions from two major cortical sources, which were localized in the medial occipital and mid-temporal regions of the contralateral hemisphere. Colocalization of dipole locations with fMRI activation sites indicated that these two major sources of the SSVEP were located in primary visual cortex (V1) and in the motion sensitive (MT/V5) areas, respectively. Minor contributions from mid-occipital (V3A) and ventral occipital (V4/V8) areas were also considered. Comparison of SSVEP phase information with timing information collected in a previous transient VEP study (Di Russo et al. [2005] Neuroimage 24:874-886) suggested that the sequence of cortical activation is similar for steady-state and transient stimulation. These results provide a detailed spatiotemporal profile of the cortical origins of the SSVEP, which should enhance its use as an efficient clinical tool for evaluating visual-cortical dysfunction as well as an investigative probe of the cortical mechanisms of visual-perceptual processing.

  18. Learned control over spinal nociception reduces supraspinal nociception as quantified by late somatosensory evoked potentials. (United States)

    Ruscheweyh, Ruth; Bäumler, Maximilian; Feller, Moritz; Krafft, Stefanie; Sommer, Jens; Straube, Andreas


    We have recently shown that subjects can learn to use cognitive-emotional strategies to suppress their spinal nociceptive flexor reflex (RIII reflex) under visual RIII feedback and proposed that this reflects learned activation of descending pain inhibition. Here, we investigated whether learned RIII suppression also affects supraspinal nociception and whether previous relaxation training increases success. Subjects were trained over 3 sessions to reduce their RIII size by self-selected cognitive-emotional strategies. Two groups received true RIII feedback (with or without previous relaxation training) and a sham group received false feedback (15 subjects per group). RIII reflexes, late somatosensory evoked potentials (SEPs), and F-waves were recorded and pain intensity ratings collected. Both true feedback groups achieved significant (P Pain intensity was significantly reduced in all 3 groups and also correlated with RIII reduction (r = 0.44, P nociception as quantified by SEPs, although effects on pain ratings were less clear. Lower motor neuron excitability as quantified by F-waves was not affected. Previous relaxation training did not significantly improve RIII feedback training success.

  19. Early magnocellular loss in glaucoma demonstrated using the pseudorandomly stimulated flash visual evoked potential. (United States)

    Klistorner, A I; Graham, S L


    Components of the pseudorandomly stimulated flash visual evoked potential (VEP) have now been identified that appear to arise predominantly from each of the magnocellular (M-cell) and parvocellular (P-cell) systems. In this study, the relative damage to magnocellular and parvocellular systems at different stages of glaucoma using pseudorandomly stimulated flash VEP was investigated. Pseudorandomly stimulated flash VEP was recorded in 15 normal eyes and 28 eyes with different stages of glaucoma using the VERIS-3 recording system (Electro-Diagnostic Imaging, San Francisco, CA). Two levels of luminance contrast of the stimulus (32% and 99%) were tested. The first slice of the second-order kernel from only the central (8 degrees) stimulated area was extracted for analysis. Data recorded from normal eyes demonstrated early saturation of the response/contrast function of the first slice of the second-order kernel. The ratio of the VEP amplitude recorded at 32% and 99% of the luminance contrast was close to unity. In eyes with early glaucoma, although the amplitude of the responses to both low- and high-contrast stimulation decreased, the relative reduction of the low-contrast VEP (M-cell) was more prominent. However, the amplitude of the high-contrast response (P-cell) declined more rapidly later in the disease. These results are consistent with relatively earlier damage of the magnocellular pathway in glaucoma.

  20. Language plasticity in aphasics after recovery: evidence from slow evoked potentials. (United States)

    Spironelli, Chiara; Angrilli, Alessandro; Pertile, Marco


    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.

  1. A Comparative Evaluation of Humphrey Perimetry and the Multi-channel Pattern Visual Evoked Potentials

    Institute of Scientific and Technical Information of China (English)

    Caiping Hu; Lezheng Wu; De-Zheng Wu; Shixian Long


    Purposes: To compare the multi-channel pattern visual evoked potentials to Humphrey perimetry in the assessment of central visual function in primary open angle glaucoma.Methods: The multi-channel checkerboard reversal PVEPs waves to full-field and half-field stimulus of 25 normal persons and 74 patients with primary open angle glaucoma were recorded and analyzed, All patients were examined using Humphrey Field Analyzer. The area of visual field corresponding to the area of retina stimulated during multi-channel PVEPs testing were analysed, straight-line correlation and regression analyses of the various multi-channel PVEPs parameters and the total dB losses were performed.Results: The multi-channel PVEPs demonstrated a low detection rate compared with Humprey perimetry in the early glaucoma, absolute latency and field loss were correlated in the late stage of glaucoma, and absolute amplitude and field loss were not correlated.Conclusions: In relation to signalling “early” loss the multi-channel PVEPs was inferior to Humphrey perimetry, in late loss of primary open angle glaucoma, multi-channel PVEPs can provide a valuable, objective complement to Humphrey perimetry.

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

    DEFF Research Database (Denmark)

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


    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...

  3. Analysis of Saccular Function With Vestibular Evoked Myogenic Potential Test in Meniere's Disease. (United States)

    Dabiri, Sasan; Yazdani, Nasrin; Esfahani, Mahdis; Tari, Niloufar; Adil, Susan; Mahvi, Zahra; Rezazadeh, Nima


    Meniere's disease is the disorder of inner ear characterized by vertigo, tinnitus and sensorineural hearing loss. The vestibular evoked myogenic potential (VEMP) test could be useful in the analysis of saccular function, and diagnosis of Meniere's disease. In this study, we've analyzed the saccular function, using VEMP test in different groups of Meniere's disease. Patients were categorized as possible, probable or definite Meniere's disease groups according to the guideline of American Academy of Otolaryngology-Head and Neck Surgery. The exclusion criteria were neuromuscular system diseases, diseases of central nervous system, inner ear disorders, conductive hearing loss, a history of ototoxic drug consumption, being a drug abuser and a positive history of inner ear surgery or manipulations. The VEMP test is the recording of positive and negative waves from sternocleidomastoid muscle that is made by an auditory click to the ear. From the total of 100 patients, the waves of VEMP test was seen in 59 patients which 19 patients had abnormal amplitude, and latency and 40 patients were with normally recorded waves. There was a significant relationship between the severity of hearing loss and a VEMP test without any recorded waves. Most of the cases with 'no wave recorded' VEMP test, were patients with severe hearing loss. However, there wasn't any relation between the pattern of hearing loss and 'no wave recorded' VEMP test. VEMP test could be a valuable diagnostic clue especially in patients with definite Meniere's disease.

  4. Repetitive magnetic stimulation affects the microenvironment of nerve regeneration and evoked potentials after spinal cord injury. (United States)

    Jiang, Jin-Lan; Guo, Xu-Dong; Zhang, Shu-Quan; Wang, Xin-Gang; Wu, Shi-Feng


    Repetitive magnetic stimulation has been shown to alter local blood flow of the brain, excite the corticospinal tract and muscle, and induce motor function recovery. We established a rat model of acute spinal cord injury using the modified Allen's method. After 4 hours of injury, rat models received repetitive magnetic stimulation, with a stimulus intensity of 35% maximum output intensity, 5-Hz frequency, 5 seconds for each sequence, and an interval of 2 minutes. This was repeated for a total of 10 sequences, once a day, 5 days in a week, for 2 consecutive weeks. After repetitive magnetic stimulation, the number of apoptotic cells decreased, matrix metalloproteinase 9/2 gene and protein expression decreased, nestin expression increased, somatosensory and motor-evoked potentials recovered, and motor function recovered in the injured spinal cord. These findings confirm that repetitive magnetic stimulation of the spinal cord improved the microenvironment of neural regeneration, reduced neuronal apoptosis, and induced neuroprotective and repair effects on the injured spinal cord.

  5. Repetitive magnetic stimulation affects the microenvironment of nerve regeneration and evoked potentials after spinal cord injury

    Directory of Open Access Journals (Sweden)

    Jin-lan Jiang


    Full Text Available Repetitive magnetic stimulation has been shown to alter local blood flow of the brain, excite the corticospinal tract and muscle, and induce motor function recovery. We established a rat model of acute spinal cord injury using the modified Allen′s method. After 4 hours of injury, rat models received repetitive magnetic stimulation, with a stimulus intensity of 35% maximum output intensity, 5-Hz frequency, 5 seconds for each sequence, and an interval of 2 minutes. This was repeated for a total of 10 sequences, once a day, 5 days in a week, for 2 consecutive weeks. After repetitive magnetic stimulation, the number of apoptotic cells decreased, matrix metalloproteinase 9/2 gene and protein expression decreased, nestin expression increased, somatosensory and motor-evoked potentials recovered, and motor function recovered in the injured spinal cord. These findings confirm that repetitive magnetic stimulation of the spinal cord improved the microenvironment of neural regeneration, reduced neuronal apoptosis, and induced neuroprotective and repair effects on the injured spinal cord.

  6. Early impairment of somatosensory evoked potentials in very young children with achondroplasia with foramen magnum stenosis. (United States)

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


    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: magnum or lumbar spinal stenosis were analysed in each age category. The ROC curve analysis showed that the most sensitive parameter in detecting the presence of foramen magnum stenosis was P37 latency in the first two age categories (magnum stenosis was IPLs N13-N20 (sensitivity 0.73, specificity 0.87), whereas in the last age category (≥8y), the most important parameter was N20 latency (sensitivity 0.75, specificity 0.77). In children with 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.

  7. Tibial somatosensory evoked potential can prognosticate for ambulatory function in subacute hemiplegic stroke. (United States)

    Hwang, Pyoungsik; Sohn, Min Kyun; Kim, Cuk-Seong; Jee, Sungju


    Early prediction of expected recovery in stroke can help in planning appropriate medical and rehabilitation interventions. Recovery of ambulation is one of the essential endpoints in stroke rehabilitation. However, the correlation of somatosensory evoked potentials (SSEP) with clinical parameters and their predictive significance are not clearly defined. We aimed to examine the association between tibial nerve SSEP and ambulatory outcomes in subacute hemiplegic stroke patients. We reviewed medical records for hemiplegic patients with first-ever stroke who received inpatient rehabilitation from January 2009 to May 2013. We excluded patients with diabetes mellitus, quadriplegia, bilateral lesions, brainstem lesions, those aged over 80 years, and those with severe musculoskeletal problems. Tibial nerve SSEP were performed when they were transferred to the rehabilitation department. SSEP findings were divided into three groups; normal, abnormal and absent response. Berg balance scale and functional ambulation category (FAC) at discharge were compared with initial tibial SSEP findings using one-way analysis of variance. Thirty-one hemiplegic patients were included. Berg balance scale and FAC were significantly different according to the SSEP (Phemiplegic patients.

  8. Laser-evoked brain potentials in patients with dissociated loss of pain and temperature sensibility. (United States)

    Bromm, B; Frieling, A; Lankers, J


    Brief heat stimuli, elicited by a CO2 laser (10.6 microns wave length), activate the most superficial cutaneous nerve terminals of the thin myelinated A delta and unmyelinated C fibres which mediate heat and pain sensations. This paper investigates late cerebral potentials (SEPs) in response to laser pulses in comparison with those to conventional electrical stimulation in 18 patients with a dissociated sensory deficit (intact mechano-sensibility and disturbed temperature and pain sensation). Patients were stimulated in the most disturbed limb (affected area) and in a corresponding control area. In all 18 patients the SEPs elicited by laser stimuli were able to identify the body site with heaviest disturbances in pain and thermo-sensibility: the SEPs from the affected area were reduced or delayed, compared to the control area. In contrast, no alterations in SEPs could be observed after conventional electrical nerve stimulation, in agreement with the normal mechano-sensibility. However, the degree of SEP modulation in response to cutaneous heat stimuli did not correspond to the severity of the subjectively reported sensory deficit. Highest correlations between sensory deficits and abnormal SEPs were found in all those patients in whom computer tomography or MR imaging documented a localized destructive process in the CNS. All patients with the smallest SEP modulations despite a considerable sensory deficit had an inflammatory aetiology. Preliminary criteria to define a laser-evoked SEP as pathological are discussed.

  9. Visual Evoked Potential Response Among Drug Abusers- A Cross Sectional Study (United States)

    Sharma, Rajeev; Thapar, Satish; Mittal, Shilekh


    Introduction There is important preclinical evidence that substance abuse may produce neurophysiological disturbances particularly in relation to altered neural synchronization in Visual Evoked Potentials (VEP). Aim The purpose of current study was to compare the latencies and amplitudes of different waveforms of VEP among different drug abusers and controls and also to identify early neurological damage so that proper counseling and timely intervention can be undertaken. Materials and Methods VEP was assessed by Data Acquisition and Analysis system in a sample of 58 drug abusers, all males, within age group of 15-45 years as well as in age matched 30 healthy controls. The peak latencies and peak to peak amplitudes of different waveforms were measured by applying one-way Anova test and unpaired t-test using SPSS version 16. Results In between drug abusers and controls, the difference in the duration of N75 and P100 waveform of VEP was found to be statistically highly significant (pdrug abusers in both eyes. Conclusion Chronic intoxication by different drugs has been extensively associated with amplitude reduction of P100 and prolonged latency of N75 and P100 reflecting an adverse effects of drug dependence on neural transmission within primary visual areas of brain. PMID:27042456

  10. Short-term food deprivation increases amplitudes of heartbeat-evoked potentials. (United States)

    Schulz, André; Ferreira de Sá, Diana S; Dierolf, Angelika M; Lutz, Annika; van Dyck, Zoé; Vögele, Claus; Schächinger, Hartmut


    Nutritional state (i.e., fasting or nonfasting) may affect the processing of interoceptive signals, but mechanisms underlying this effect remain unclear. We investigated 16 healthy women on two separate days: when satiated (standardized food intake) and after an 18-h food deprivation period. On both days, heartbeat-evoked potentials (HEPs) and cardiac and autonomic nervous system activation indices (heart rate, normalized low frequency heart rate variability [nLF HRV]) were assessed. The HEP is an EEG pattern that is considered an index of cortical representation of afferent cardiovascular signals. Average HEP activity (R wave +455-595 ms) was enhanced during food deprivation compared to normal food intake. Cardiac activation did not differ between nutritional conditions. Our results indicate that short-term food deprivation amplifies an electrophysiological correlate of the cortical representation of visceral-afferent signals originating from the cardiovascular system. This effect could not be attributed to increased cardiac activation, as estimated by heart rate and nLF HRV, after food deprivation. © 2014 Society for Psychophysiological Research.

  11. Visual evoked potentials for intraoperative neurophysiologic monitoring using total intravenous anesthesia. (United States)

    Wiedemayer, Helmut; Fauser, Barbara; Armbruster, W; Gasser, Thomas; Stolke, Dietmar


    Conflicting reports on the usefulness of intraoperative monitoring of visual function by means of visual evoked potentials (VEPs) initiated this study. In 32 patients without visual problems, VEPs were recorded to evaluate the reliability for intraoperative monitoring with total intravenous anesthesia. All patients underwent noncranial surgery. Using a standard technique, VEPs were recorded preoperatively in the awake patients and after induction of anesthesia during surgery. A total of 1436 intraoperative traces were recorded and analyzed. A minor prolongation of the P100 latency of 8% and a more pronounced attenuation of the P100-N145 amplitude of 60% were observed in the anesthetized patients. In most of the anesthetized patients, a stable recording of VEPs was not obtainable. In 4 patients (12.5%), clearly identifiable VEP peaks were detected in more than 90% of the traces recorded intraoperatively. In 88% of the patients, reproducible VEPs were obtained in less than 75% of the intraoperative traces only. We concluded that with standard recording techniques and total intravenous anesthesia, intraoperative VEP monitoring in surgically anesthetized patients is not reliable.

  12. [A significant increase in intraoperative flash visual evoked potential amplitude during craniopharyngioma surgery-case report]. (United States)

    Kawaguchi, Tomohiro; Ogawa, Yoshikazu; Fujiwara, Satoru; Tominaga, Teiji


    The flash visual evoked potential (VEP) is a useful diagnostic modality for visual preservation during surgery. Decreased VEP amplitude is recognized to indicate visual deterioration;however, whether intraoperative VEP can detect visual improvement remains unclear. We describe a craniopharyngioma case with a significant increase in VEP amplitude during surgery. A 67-year-old woman presented with progressive gait disturbance and impaired consciousness. Head magnetic resonance imaging demonstrated a sellar-suprasellar tumor compressing the optic chiasm upward with significant ventricular dilation. Her Glasgow Coma Scale was E3V3M5. Visual fields and acuity could not be examined because of impaired consciousness, and she could not see/recognize objects on a table. Preoperative VEP showed reproducible waveforms. Tumor removal by the extended transsphenoidal approach was performed with VEP monitoring. Increased VEP amplitude was observed after dural incision and persisted until the surgery ended. Postoperative VEP waveforms were also reproducible, but visual fields/acuity could not be examined because of cognitive dysfunction. Useful visual function was restored, and she became independent in daily life. The histological diagnosis was craniopharyngioma. The patient underwent ventriculo-peritoneal shunting for hydrocephalus 16 days after tumor removal. The postoperative course was uneventful and she was transferred to another hospital for rehabilitation. Intraoperative VEP may indicate visual improvement during surgery, which is a useful objective assessment for visual function in patients with impaired consciousness and cognitive dysfunction.

  13. Effect of different stimulus configurations on the visual evoked potential (VEP). (United States)

    Yadav, Naveen K; Ludlam, Diana P; Ciuffreda, Kenneth J


    The purpose of this study was to assess changes in the response profile of the pattern visual evoked potential (VEP) using three stimulus configurations simulating visual-field scotomas: central circular and central blank fields increasing incrementally in diameter from 1° to 15°, hemi-field, and quadrant patterns. Five visually normal adult subjects (ages 22-68 years) were tested binocularly at 1 m for each stimulus configuration on 5 separate days. A checkerboard test pattern (64 × 64 black-and-white checks, 85% contrast, 64 cd/m(2) luminance, 20 s of stimulus duration, 2-Hz temporal frequency) was used. The group mean VEP amplitude increased in a linear manner with increase in the central circular diameter (y = 0.805x + 2.00; r = 0.986) and decrease in central blank field diameter (y = -0.769x + 16.22; r = 0.987). There was no significant change in latency in nearly all cases. The group mean coefficient of variability results indicated that the VEP amplitude was repeatable for the different stimulus configurations. The finding of VEP response linearity for the circular stimulus fields, and repeatability for all stimulus configurations, suggests that the clinician may be able to use the VEP technique with the suggested test patterns as a rapid and simple tool for objective assessment for several types of visual-field defects for a range of abnormal visual conditions and special populations.

  14. [Adaptive estimation of contrast thresholds using the visual evoked potential (VEP)]. (United States)

    Meigen, Thomas; Kley, Franziska


    The visual evoked potential (VEP) can be used to objectively estimate sensory thresholds. Recently, we developed an adaptive procedure for this threshold estimation based on a Fourier analysis of steady-state responses during the recording. In this study we quantified the reduction in recording time of this adaptive procedure. Steady-state VEPs to pattern reversal (f = 8.3 Hz) of checkerboards with 8 contrast values between 0.64% and 82% were recorded monocularly. Adaptive and non-adaptive recordings were performed for full correction (fc) and for blurred stimulus patterns (+1.5 D and +3.0D). VEP contrast thresholds were defined by the lowest contrast condition that showed a significant response. An ANOVA of the VEP thresholds showed significant effects (p VEP, non-adaptive VEP) and "correction" (fc, fc + 1.5D, fc + 3.0D). Compared to non-adaptive recordings, adaptive recordings showed thresholds that were significantly reduced and closer to psychophysical contrast thresholds. By applying the adaptive procedure the recording time can be reduced by a factor of about 2 when compared to the non-adaptive procedure. The new adaptive VEP procedure may help to improve the correlation of electrophysiological and psychophysical estimates of sensory thresholds and may accelerate functional testing in the clinical routine.

  15. Early detection of hepatic encephalopathy by recording visual evoked potential (VEP). (United States)

    Zamir, Doron; Storch, Shimon; Kovach, Ivan; Storch, Rita; Zamir, Chen


    The visual evoked potential (VEP) record in response to a pattern stimulus is a non invasive and reliable method of detecting central and peripheral nerve system abnormalities. VEP recording have been used in animals with fulminant hepatic failure, and also in-patients with hepatic encephalopathy and acute severe hepatitis. Our aims were: a. to evaluate the potency of PVEP in assessing hepatic encephalopathy. b. to find the rate of pathologic PVEP in patients with advanced liver cirrhosis. VEP was recorded in 14 chronic liver cirrhotic patients (6 alcoholic, 6 HCV-related, 2 cryptogenic) and 14 controls. Patients with any neurologic abnormalities were excluded from the study. All patients were subjected to the Mental State Score (MSS) test, and venous blood ammonia was measured on the same day of VEP recording. In 10/14 (71%) patients some VEP recording abnormality was detected. In the cirrhotic patients, P100 latency was significantly longer (P VEP developed hepatic encephalpathy during a follow-up of one year, compared to one out of 4 patients with no pathology on VEP recording. VEP recording may be a valuable tool in assessing patients with early hepatic encephalopathy and in predicting encephalopathy.

  16. Visual evoked potential (VEP) and multifocal electroretinogram (mfERG) in ocular syphilitic posterior segment inflammation. (United States)

    Alexander, Philip; Wen, Yaqin; Baxter, Julia M; Tint, Naing L; Browning, Andrew C; Amoaku, Winfried M


    The aim of this study is to correlate multifocal electroretinogram (mfERG) and visual evoked potential (VEP) changes with visual acuity and clinical features in patients with posterior segment inflammation secondary to syphilis. A retrospective interventional case series of 4 patients with visual loss secondary to syphilitic uveitis is reported. The mfERG (P1) showed diminished amplitudes and prolonged latency in 7 affected eyes. Visual acuity rapidly improved 2 weeks after initiation of therapy. OCT demonstrated anatomical recovery at 1 month. In three patients, visual acuity was restored to 6/6 at 6-9 months but mfERG responses remained significantly reduced and delayed for 12-15 months before recovery to normal levels. One patient developed a retinal detachment, but achieved 6/9 vision at 30 months. VEP changes, interpreted in combination with mfERG responses, showed evidence of optic nerve involvement in 6 eyes. Ocular findings, including posterior placoid chorioretinitis, are important diagnostic features of secondary and tertiary syphilis. Visual acuity and clinical recovery occur early with appropriate diagnosis and treatment, and precede full electrophysiological recovery of the outer retina-RPE complex. Ophthalmologists have the opportunity to play a key role in undetected or missed diagnoses of syphilis, and with appropriate treatment the visual prognosis is excellent.

  17. Dominant Eye and Visual Evoked Potential of Patients with Myopic Anisometropia

    Directory of Open Access Journals (Sweden)

    Qing Wang


    Full Text Available A prospective nonrandomized controlled study was conducted to explore the association between ocular dominance and degree of myopia in patients with anisometropia and to investigate the character of visual evoked potential (VEP in high anisometropias. 1771 young myopia cases including 790 anisometropias were recruited. We found no significant relation between ocular dominance and spherical equivalent (SE refraction in all subjects. On average for subjects with anisometropia 1.0–1.75 D, there was no significant difference in SE power between dominant and nondominant eyes, while, in SE anisometropia ≥1.75 D group, the degree of myopia was significantly higher in nondominant eyes than in dominant eyes. The trend was more significant in SE anisometropia ≥2.5 D group. There was no significant difference in higher-order aberrations between dominant eye and nondominant eye either in the whole study candidates or in any anisometropia groups. In anisometropias >2.0 D, the N75 latency of nondominant eye was longer than that of dominant eye. Our results suggested that, with the increase of anisometropia, nondominant eye had a tendency of higher refraction and N75 wave latency of nondominant eye was longer than that of dominant eye in high anisometropias.

  18. A comparison of commercial auditory evoked potential units: the midpriced and luxury units. (United States)

    Ferraro, J A; Ruth, R R


    This report represents the second of two providing a consumer-oriented comparison of commercially available auditory evoked potential units. The units compared here were those whose basic price was between $10,000-$30,000 ("midpriced"), and greater than $30,000 ("luxury"). The midpriced group included the Amplaid MK15, Bio-Logic Navigator and Traveler LT, Cadwell 5200A and Quantum 84, GSI-50, Nicolet CA-2000 and Compact Auditory, Nihon-Kohden Neuropak IV Mini, Madsen ERA2250, Siegen (Dantec) Neuroscope, and Tracor Nomad. The luxury units comprised the Bio-Logic Brain Atlas, Cadwell Spectrum 32 and Nicolet Pathfinder. Descriptive information and the names and addresses of users were solicited from the manufacturers for each of the above units. Questionnaires were sent to the users asking them for information on how their unit was used and to rate some of its features. The midpriced and luxury units offer more flexibility and options than less expensive (i.e., "economy") units. However, the basis for a given unit's price versus another's was not always apparent by a comparison of features or options. In general, users of the midpriced and luxury units rated the majority of their instruments' features highly. The lowest ratings were received for some aspect of the printer or print-out, and portability.

  19. Effects of light deprivation on visual evoked potentials in migraine without aura

    Directory of Open Access Journals (Sweden)

    Pierelli Francesco


    Full Text Available Abstract Background The mechanisms underlying the interictal habituation deficit of cortical visual evoked potentials (VEP in migraine are not well understood. Abnormal long-term functional plasticity of the visual cortex may play a role and it can be assessed experimentally by light deprivation (LD. Methods We have compared the effects of LD on VEP in migraine patients without aura between attacks (MO, n = 17 and in healthy volunteers (HV, n = 17. Six sequential blocks of 100 averaged VEP at 3.1 Hz were recorded before and after 1 hour of LD. We measured VEP P100 amplitude of the 1st block of 100 sweeps and its change over 5 sequential blocks of 100 responses. Results In HV, the consequence of LD was a reduction of 1st block VEP amplitude and of the normal habituation pattern. By contrast, in MO patients, the interictal habituation deficit was not significantly modified, although 1st block VEP amplitude, already lower than in HV before LD, further decreased after LD. Conclusions Light deprivation is thought to decrease both excitatory and subsequent inhibitory processes in visual cortex, which is in line with our findings in healthy volunteers. The VEP results in migraine patients suggest that early excitation was adequately suppressed, but not the inhibitory mechanisms occurring during long term stimulation and habituation. Accordingly, deficient intracortical inhibition is unlikely to be a primary factor in migraine pathophysiology and the habituation deficit.

  20. Attachment style moderates partner presence effects on pain: a laser-evoked potentials study. (United States)

    Krahé, Charlotte; Paloyelis, Yannis; Condon, Heather; Jenkinson, Paul M; Williams, Steven C R; Fotopoulou, Aikaterini


    Social support is crucial for psychological and physical well-being. Yet, in experimental and clinical pain research, the presence of others has been found to both attenuate and intensify pain. To investigate the factors underlying these mixed effects, we administered noxious laser stimuli to 39 healthy women while their romantic partner was present or absent, and measured pain ratings and laser-evoked potentials (LEPs) to assess the effects of partner presence on subjective pain experience and underlying neural processes. Further, we examined whether individual differences in adult attachment style (AAS), alone or in interaction with the partner's level of attentional focus (manipulated to be either on or away from the participant) might modulate these effects. We found that the effects of partner presence vs absence on pain-related measures depended on AAS but not partner attentional focus. The higher participants' attachment avoidance, the higher pain ratings and N2 and P2 local peak amplitudes were in the presence compared with the absence of the romantic partner. As LEPs are thought to reflect activity relating to the salience of events, our data suggest that partner presence may influence the perceived salience of events threatening the body, particularly in individuals who tend to mistrust others.

  1. The reproducibility of binocular pattern reversal visual evoked potentials: a single subject design. (United States)

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


    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.

  2. Toward brain-computer interface based wheelchair control utilizing tactually-evoked event-related potentials (United States)


    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

  3. Relationship between vitamin D deficiency and visually evoked potentials in multiple sclerosis. (United States)

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


    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.

  4. Cortical inhibition of laser pain and laser-evoked potentials by non-nociceptive somatosensory input. (United States)

    Testani, Elisa; Le Pera, Domenica; Del Percio, Claudio; Miliucci, Roberto; Brancucci, Alfredo; Pazzaglia, Costanza; De Armas, Liala; Babiloni, Claudio; Rossini, Paolo Maria; Valeriani, Massimiliano


    Although the inhibitory action that tactile stimuli can have on pain is well documented, the precise timing of the interaction between the painful and non-painful stimuli in the central nervous system is unclear. The aim of this study was to investigate this issue by measuring the timing of the amplitude modulation of laser evoked potentials (LEPs) due to conditioning non-painful stimuli. LEPs were recorded from 31 scalp electrodes in 10 healthy subjects after painful stimulation of the right arm (C6-C7 dermatomes). Non-painful electrical stimuli were applied by ring electrodes on the second and third finger of the right hand. Electrical stimuli were delivered at +50, +150, +200 and +250 ms interstimulus intervals (ISIs) after the laser pulses. LEPs obtained without any conditioning stimulation were used as a baseline. As compared to the baseline, non-painful electrical stimulation reduced the amplitude of the vertex N2/P2 LEP component and the laser pain rating when electrical stimuli followed the laser pulses only at +150 and +200 ms ISIs. As at these ISIs the collision between the non-painful and painful input is likely to take place at the cortical level, we can conclude that the late processing of painful (thermal) stimuli is partially inhibited by the processing of non-painful (cutaneous) stimuli within the cerebral cortex. Moreover, our results do not provide evidence that non-painful inputs can inhibit pain at a lower level, including the spinal cord.

  5. Affective touch and attachment style modulate pain: a laser-evoked potentials study (United States)

    Drabek, Marianne M.; Paloyelis, Yannis; Fotopoulou, Aikaterini


    Affective touch and cutaneous pain are two sub-modalities of interoception with contrasting affective qualities (pleasantness/unpleasantness) and social meanings (care/harm), yet their direct relationship has not been investigated. In 50 women, taking into account individual attachment styles, we assessed the role of affective touch and particularly the contribution of the C tactile (CT) system in subjective and electrophysiological responses to noxious skin stimulation, namely N1 and N2-P2 laser-evoked potentials. When pleasant, slow (versus fast) velocity touch was administered to the (non-CT-containing) palm of the hand, higher attachment anxiety predicted increased subjective pain ratings, in the same direction as changes in N2 amplitude. By contrast, when pleasant touch was administered to CT-containing skin of the arm, higher attachment anxiety predicted attenuated N1 and N2 amplitudes. Higher attachment avoidance predicted opposite results. Thus, CT-based affective touch can modulate pain in early and late processing stages (N1 and N2 components), with the direction of effects depending on attachment style. Affective touch not involving the CT system seems to affect predominately the conscious perception of pain, possibly reflecting socio-cognitive factors further up the neurocognitive hierarchy. Affective touch may thus convey information about available social resources and gate pain responses depending on individual expectations of social support. This article is part of the themed issue ‘Interoception beyond homeostasis: affect, cognition and mental health’. PMID:28080967

  6. EEG-based classification of video quality perception using steady state visual evoked potentials (SSVEPs) (United States)

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


    Objective. Recent studies exploit the neural signal recorded via electroencephalography (EEG) to get a more objective measurement of perceived video quality. Most of these studies capitalize on the event-related potential component P3. We follow an alternative approach to the measurement problem investigating steady state visual evoked potentials (SSVEPs) as EEG correlates of quality changes. Unlike the P3, SSVEPs are directly linked to the sensory processing of the stimuli and do not require long experimental sessions to get a sufficient signal-to-noise ratio. Furthermore, we investigate the correlation of the EEG-based measures with the outcome of the standard behavioral assessment. Approach. As stimulus material, we used six gray-level natural images in six levels of degradation that were created by coding the images with the HM10.0 test model of the high efficiency video coding (H.265/MPEG-HEVC) using six different compression rates. The degraded images were presented in rapid alternation with the original images. In this setting, the presence of SSVEPs is a neural marker that objectively indicates the neural processing of the quality changes that are induced by the video coding. We tested two different machine learning methods to classify such potentials based on the modulation of the brain rhythm and on time-locked components, respectively. Main results. Results show high accuracies in classification of the neural signal over the threshold of the perception of the quality changes. Accuracies significantly correlate with the mean opinion scores given by the participants in the standardized degradation category rating quality assessment of the same group of images. Significance. The results show that neural assessment of video quality based on SSVEPs is a viable complement of the behavioral one and a significantly fast alternative to methods based on the P3 component.

  7. Long-latency auditory evoked potentials with verbal and nonverbal stimuli. (United States)

    Oppitz, Sheila Jacques; Didoné, Dayane Domeneghini; Silva, Débora Durigon da; Gois, Marjana; Folgearini, Jordana; Ferreira, Geise Corrêa; Garcia, Michele Vargas


    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. 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. A total of 30 subjects with normal hearing were assessed, aged 18-32 years old, matched by gender. Nonverbal stimuli were used (tone burst; 1000Hz - frequent and 4000Hz - rare); and verbal (/ba/ - frequent; /ga/, /da/, and /di/ - rare). Considering the component N2 for tone burst, the lowest latency found was 217.45ms for the BA/DI stimulus; the highest latency found was 256.5ms. For the P3 component, the shortest latency with tone burst stimuli was 298.7 with BA/GA stimuli, the highest, was 340ms. 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. 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. Copyright © 2015 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.

  8. 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


    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.

  9. Auditory evoked potentials in young patients with Down syndrome. Event-related potentials (P3) and histaminergic system. (United States)

    Seidl, R; Hauser, E; Bernert, G; Marx, M; Freilinger, M; Lubec, G


    Subjects with Down syndrome exhibit various types of cognitive impairment. Besides abnormalities in a number of neurotransmitter systems (e.g. cholinergic), histaminergic deficits have recently been identified. Brainstem auditory evoked potentials (BAEPs) and auditory event-related potentials (ERPs), were recorded from 10 children (aged 11-20 years) with Down syndrome and from 10 age- and sex-matched healthy control subjects. In Down subjects, BAEPs revealed shortened latencies for peaks III and V with shortened interpeak latencies I-III and I-V. ERPs showed a delay of components N1, P2, N2 and P3. In addition, subjects with Down syndrome failed to show P3 amplitude reduction during repeated stimulation. To evaluate the cognitive effects of histaminergic dysfunction, ERPs were recorded from 12 healthy adults (aged 20-28 years) before and after antihistaminergic intervention (pheniramine) compared to placebo. Whereas components N1, P2, N2 remained unchanged after H1-receptor antagonism, P3 latency increased and P3 amplitude showed no habituation in response to repeated stimulation. The results suggest that the characteristic neurofunctional abnormalities present in children with Down syndrome must be the consequence of a combination of structural and neurochemical aberrations. The second finding was that antihistaminergic treatment affects information processing tested by ERPs similar to that seen with anticholinergic treatment.

  10. Research on steady-state visual evoked potentials in 3D displays (United States)

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


    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-value<0.05) between large and small disparity angle, and the signal-to-noise ratios (SNRs) of small disparity angles is higher than those of large disparity angles. The 3D stimuli with smaller disparity and lower crosstalk are more suitable for applications based on the results of 3D perception and SSVEP responses (SNR). Furthermore, we can infer the 3D perception of users by SSVEP responses, and modify the proper disparity of 3D images automatically in the future.

  11. [Contribution of cognitive evoked potentials for detecting early cognitive disorders in multiple sclerosis]. (United States)

    Magnié, M N; Bensa, C; Laloux, L; Bertogliati, C; Faure, S; Lebrun, C


    In Multiple Sclerosis (MS), one of the most frequent neurological diseases in young adults, cognitive dysfunctions have been under considered whereas their evolution may produce a fronto-sous-cortical deterioration and more than half of the MS patients present such dysfunctions. Nevertheless sensory evoked-potentials are classically used in this disease, event-related potentials (ERP) are not included in the clinical exploration of MS. Two studies are presented aimed at further tracking the usefulness of ERP for detecting early cognitive dysfunctions in MS. All of the patients presented a relapsing remitting MS for less than 5 years with a moderate physical handicap and complained from their memory. They performed a neuropsychological set and ERP were elicited using the oddball paradigm in both modalities, visual and auditory. In the first study, 10 patients without cognitive dysfunction at the neuropsychological evaluation and 10 patients with an attention deficit participated with 10 age-matched controls. In the second study, 10 patients with memory impairment at the neuropsychological evaluation and 10 age-matched controls were included. Our data argue for an earlier modification of ERP parameters in the visual modality than in the auditory one, even before the modification of cognitive scores. In both studies, P300 parameters were correlated to neuropsychological performances (and especially to the attention examination in the first study and to memory tests in the second study) in both modalities. Taking into account the clinical usefulness of ERPs, it is nowadays important to include this electrophysiological method in evaluation and follow-up of MS, and not only using the auditory modality but also the visual presentation in order to detect earlier cognitive dysfunctions even before modification of neuropsychological performances.

  12. Measurement of Electroretinograms and Visually Evoked Potentials in Awake Moving Mice.

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    Yusuke Tomiyama

    Full Text Available The development of new treatments for intractable retinal diseases requires reliable functional assessment tools for animal models. In vivo measurements of neural activity within visual pathways, including electroretinogram (ERG and visually evoked potential (VEP recordings, are commonly used for such purposes. In mice, the ERG and VEPs are usually recorded under general anesthesia, a state that may alter sensory transduction and neurotransmission, but seldom in awake freely moving mice. Therefore, it remains unknown whether the electrophysiological assessment of anesthetized mice accurately reflects the physiological function of the visual pathway. Herein, we describe a novel method to record the ERG and VEPs simultaneously in freely moving mice by immobilizing the head using a custom-built restraining device and placing a rotatable cylinder underneath to allow free running or walking during recording. Injection of the commonly used anesthetic mixture xylazine plus ketamine increased and delayed ERG oscillatory potentials by an average of 67.5% and 36.3%, respectively, compared to unanesthetized mice, while having minimal effects on the a-wave and b-wave. Similarly, components of the VEP were enhanced and delayed by up to 300.2% and 39.3%, respectively, in anesthetized mice. Our method for electrophysiological recording in conscious mice is a sensitive and robust means to assess visual function. It uses a conventional electrophysiological recording system and a simple platform that can be built in any laboratory at low cost. Measurements using this method provide objective indices of mouse visual function with high precision and stability, unaffected by anesthetics.

  13. Effect of renewed SS-cream on spinal somatosensory evoked potential in rabbits

    Institute of Scientific and Technical Information of China (English)

    LongTian; Zhong-ChengXin; HuaXin; JieFu; Yi-MingYuan; Wu-JiangLiu; ChunYang


    Aim:The effect of a renewed SS-cream (RSSC) on the treatment of premature ejaculation (PE) was evaluated and compared with the original SS-cream (OSSC).Methods: Sixty male white New Zealand rabbits,weighing 2.5kg-3.0kg,were divided at random into 3 groups:the RSSC,OSSC and placebo groups.The spinal somatosensory evoked potential (SSEP) elicited by electric stimulation of the glans penis with disk electrode was investigated with an electrophysiograph (Poseidomn,Shanghai,China) before and 10,30 and 60 min after drug or placebo application on the glans.The Onset and the N1 latencies and the amplitude of SSEP were recorded and analyzed. Results:There was no significant difference (P>0.05) in the mean Onset and N1 latency of SSEP among the 3 groups before drug application.Compared with the pre-application value,the mean Onset and N 1 latencies in the RSSC and OSSC groups were significantly prolonged at 10,30 and 60 min after treatment (P0.05) in the placebo group.The mean Onset latency of RSSC at 10 and 30 min and that of OSSC at 30 min were significantly delayed (P<0.05) compared with the placebo group.The mean N1 latency of RSSC at 30 and 60 min and that of OSSC group at 30 min were also significantly delayed (P<0.05).Conclusion:RSSC delays the latencies of SSEP,suggesting a local desensitizing effect on the sensory receptor of the glans penis dorsal nerve,which provides the potential for PE treatment.The desensitizing effect of RSSC is higher than that of OSSC.( Asian J Androl 2004 Mar;6:15-18)

  14. Dichoptic stimulation improves detection of glaucoma with multifocal visual evoked potentials. (United States)

    Arvind, Hemamalini; Klistorner, Alexander; Graham, Stuart; Grigg, John; Goldberg, Ivan; Klistorner, Asya; Billson, Frank A


    To determine whether simultaneous binocular (dichoptic) stimulation for multifocal visual evoked potentials (mfVEP) detects glaucomatous defects and decreases intereye variability. Twenty-eight patients with glaucoma and 30 healthy subjects underwent mfVEP on monocular and dichoptic stimulation. Dichoptic stimulation was presented with the use of virtual reality goggles (recording time, 7 minutes). Monocular mfVEPs were recorded sequentially for each eye (recording time, 10 minutes). Comparison of mean relative asymmetry coefficient (RAC; calculated as difference in amplitudes between eyes/sum of amplitudes of both eyes at each segment) on monocular and dichoptic mfVEP revealed significantly lower RAC on dichoptic (0.003 +/- 0.03) compared with monocular testing (-0.02 +/- 0.04; P = 0.002). In all 28 patients, dichoptic mfVEP identified defects with excellent topographic correspondence. Of 56 hemifields (28 eyes), 33 had Humphrey visual field (HFA) scotomas, all of which were detected by dichoptic mfVEP. Among 23 hemifields with normal HFA, two were abnormal on monocular and dichoptic mfVEP. Five hemifields (five patients) normal on HFA and monocular mfVEP were abnormal on dichoptic mfVEP. In all five patients, corresponding rim changes were observed on disc photographs. Mean RAC of glaucomatous eyes was significantly higher on dichoptic (0.283 +/- 0.18) compared with monocular (0.199 +/- 0.12) tests (P = 0.0006). Dichoptic mfVEP not only detects HFA losses, it may identify early defects in areas unaffected on HFA and monocular mfVEP while reducing testing time by 30%. Asymmetry was tighter among healthy subjects but wider in patients with glaucoma on simultaneous binocular stimulation, which is potentially a new tool in the early detection of glaucoma.

  15. Rapid and Objective Assessment of Neural Function in Autism Spectrum Disorder Using Transient Visual Evoked Potentials (United States)

    Siper, Paige M.; Zemon, Vance; Gordon, James; George-Jones, Julia; Lurie, Stacey; Zweifach, Jessica; Tavassoli, Teresa; Wang, A. Ting; Jamison, Jesslyn; Buxbaum, Joseph D.; Kolevzon, Alexander


    Objective There is a critical need to identify biomarkers and objective outcome measures that can be used to understand underlying neural mechanisms in autism spectrum disorder (ASD). Visual evoked potentials (VEPs) offer a noninvasive technique to evaluate the functional integrity of neural mechanisms, specifically visual pathways, while probing for disease pathophysiology. Methods Transient VEPs (tVEPs) were obtained from 96 unmedicated children, including 37 children with ASD, 36 typically developing (TD) children, and 23 unaffected siblings (SIBS). A conventional contrast-reversing checkerboard condition was compared to a novel short-duration condition, which was developed to enable objective data collection from severely affected populations who are often excluded from electroencephalographic (EEG) studies. Results Children with ASD showed significantly smaller amplitudes compared to TD children at two of the earliest critical VEP components, P60-N75 and N75-P100. SIBS showed intermediate responses relative to ASD and TD groups. There were no group differences in response latency. Frequency band analyses indicated significantly weaker responses for the ASD group in bands encompassing gamma-wave activity. Ninety-two percent of children with ASD were able to complete the short-duration condition compared to 68% for the standard condition. Conclusions The current study establishes the utility of a short-duration tVEP test for use in children at varying levels of functioning and describes neural abnormalities in children with idiopathic ASD. Implications for excitatory/inhibitory balance as well as the potential application of VEP for use in clinical trials are discussed. PMID:27716799

  16. Direct motor evoked potentials and cortical mapping using the NIM® nerve monitoring system: A technical note. (United States)

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


    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.

  17. Changes in somatosensory evoked potentials elicited by stimulation of upper-limb and lower-limb nerves in amyotrophic lateral sclerosis patients

    Institute of Scientific and Technical Information of China (English)

    Ying Zheng; Zhaohuan Zhang; Weihua Wu; Zhongxin Zhao


    This study observed the changes in somatosensory evoked potentials between patients with amyotrophic lateral sclerosis (ALS) and healthy controls to evaluate the function of the central deep somatosensory pathway. In patients with ALS, 28 patients (54%) showed an abnormality in somatosensory evoked potentials. All had abnormal lower limb somatosensory evoked potentials. Compared with healthy controls, the abnormality in somatosensory evoked potential was characterized by prolonged N20, P2, N2 latency and central conduction time, with or without a decrease in wave amplitude or disappearance of waveform. Results showed marked alterations in the somatosensory evoked potential in cortical components of the upper and lower limb in 54% of patients with ALS, and confirmed that patients with ALS may also have a defective deep somatosensory pathway, particularly an abnormal central deep somatosensory pathway.

  18. The effect of transcranial direct current stimulation on contrast sensitivity and visual evoked potential amplitude in adults with amblyopia (United States)

    Ding, Zhaofeng; Li, Jinrong; Spiegel, Daniel P.; Chen, Zidong; Chan, Lily; Luo, Guangwei; Yuan, Junpeng; Deng, Daming; Yu, Minbin; Thompson, Benjamin


    Amblyopia is a neurodevelopmental disorder of vision that occurs when the visual cortex receives decorrelated inputs from the two eyes during an early critical period of development. Amblyopic eyes are subject to suppression from the fellow eye, generate weaker visual evoked potentials (VEPs) than fellow eyes and have multiple visual deficits including impairments in visual acuity and contrast sensitivity. Primate models and human psychophysics indicate that stronger suppression is associated with greater deficits in amblyopic eye contrast sensitivity and visual acuity. We tested whether transcranial direct current stimulation (tDCS) of the visual cortex would modulate VEP amplitude and contrast sensitivity in adults with amblyopia. tDCS can transiently alter cortical excitability and may influence suppressive neural interactions. Twenty-one patients with amblyopia and twenty-seven controls completed separate sessions of anodal (a-), cathodal (c-) and sham (s-) visual cortex tDCS. A-tDCS transiently and significantly increased VEP amplitudes for amblyopic, fellow and control eyes and contrast sensitivity for amblyopic and control eyes. C-tDCS decreased VEP amplitude and contrast sensitivity and s-tDCS had no effect. These results suggest that tDCS can modulate visual cortex responses to information from adult amblyopic eyes and provide a foundation for future clinical studies of tDCS in adults with amblyopia. PMID:26763954

  19. Steady-state motion visual evoked potentials produced by oscillating Newton's rings: implications for brain-computer interfaces.

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    Jun Xie

    Full Text Available In this study, we utilize a special visual stimulation protocol, called motion reversal, to present a novel steady-state motion visual evoked potential (SSMVEP-based BCI paradigm that relied on human perception of motions oscillated in two opposite directions. Four Newton's rings with the oscillating expansion and contraction motions served as visual stimulators to elicit subjects' SSMVEPs. And four motion reversal frequencies of 8.1, 9.8, 12.25 and 14 Hz were tested. According to Canonical Correlation Analysis (CCA, the offline accuracy and ITR (mean ± standard deviation over six healthy subjects were 86.56 ± 9.63% and 15.93 ± 3.83 bits/min, respectively. All subjects except one exceeded the level of 80% mean accuracy. Circular Hotelling's T-Squared test (T2 circ also demonstrated that most subjects exhibited significantly strong stimulus-locked SSMVEP responses. The results of declining exponential fittings exhibited low-adaptation characteristics over the 100-s