Thomas C Bulea
Full Text Available Accumulating evidence suggests cortical circuits may contribute to control of human locomotion. Here, noninvasive electroencephalography (EEG recorded from able-bodied volunteers during a novel treadmill walking paradigm was used to assess neural correlates of walking. A systematic processing method, including a recently developed subspace reconstruction algorithm, reduced movement-related EEG artifact prior to independent component analysis and dipole source localization. We quantified cortical activity while participants tracked slow and fast target speeds across two treadmill conditions: an active mode that adjusted belt speed based on user movements and a passive mode reflecting a typical treadmill. Our results reveal frequency specific, multi-focal task related changes in cortical oscillations elicited by active walking. Low γ band power, localized to the prefrontal and posterior parietal cortices, was significantly increased during double support and early swing phases, critical points in the gait cycle since the active controller adjusted speed based on pelvis position and swing foot velocity. These phasic γ band synchronizations provide evidence that prefrontal and posterior parietal networks, previously implicated in visuo-spatial and somotosensory integration, are engaged to enhance lower limb control during gait. Sustained μ and β band desynchronization within sensorimotor cortex, a neural correlate for movement, was observed during walking thereby validating our methods for isolating cortical activity. Our results also demonstrate the utility of EEG recorded during locomotion for probing the multi-regional cortical networks which underpin its execution. For example, the cortical network engagement elicited by the active treadmill suggests that it may enhance neuroplasticity for more effective motor training.
SA Journal of Radiology ... Magnetic resonance imaging (MRI) has been associated with either diffuse polymicrogyria around the entire extent of the sylvian fissure or in the posterior aspects of the parietal regions, in which case it is called posterior parietal ... This article discusses the possible embryological origin of these
Visual perception involves complex and active processes. We will start by explaining why visual perception is dependent on visuospatial working memory, especially the spatiotemporal integration of the perceived elements through the ocular exploration of visual scenes. Then we will present neuropsychology, transcranial magnetic stimulation and neuroimaging data yielding information on the specific role of the posterior parietal cortex of the right hemisphere in visuospatial working memory. Within the posterior parietal cortex, neuropsychology data also suggest that there might be dissociated neural substrates for deployment of attention (superior parietal lobules) and spatiotemporal integration (right inferior parietal lobule). Copyright © 2016 Elsevier Masson SAS. All rights reserved.
Graf, Arnulf B A; Andersen, Richard A
Oculomotor function critically depends on how signals representing saccade direction and eye position are combined across neurons in the lateral intraparietal (LIP) area of the posterior parietal cortex. Here we show that populations of parietal neurons exhibit correlated variability, and that using these interneuronal correlations yields oculomotor predictions that are more accurate and also less uncertain. The structure of LIP population responses is therefore essential for reliable read-out of oculomotor behaviour.
Sutoh, Chihiro; Matsuzawa, Daisuke; Hirano, Yoshiyuki; Yamada, Makiko; Nagaoka, Sawako; Chakraborty, Sudesna; Ishii, Daisuke; Matsuda, Shingo; Tomizawa, Haruna; Ito, Hiroshi; Tsuji, Hiroshi; Obata, Takayuki; Shimizu, Eiji
Cognitive restructuring is a fundamental method within cognitive behavioural therapy of changing dysfunctional beliefs into flexible beliefs and learning to react appropriately to the reality of an anxiety-causing situation. To clarify the neural mechanisms of cognitive restructuring, we designed a unique task that replicated psychotherapy during a brain scan. The brain activities of healthy male participants were analysed using functional magnetic resonance imaging. During the brain scan, participants underwent Socratic questioning aimed at cognitive restructuring regarding the necessity of handwashing after using the restroom. The behavioural result indicated that the Socratic questioning effectively decreased the participants' degree of belief (DOB) that they must wash their hands. Alterations in the DOB showed a positive correlation with activity in the left posterior parietal cortex (PPC) while the subject thought about and rated own belief. The involvement of the left PPC not only in planning and decision-making but also in conceptualization may play a pivotal role in cognitive restructuring.
Magen, Hagit; Emmanouil, Tatiana-Aloi; McMains, Stephanie A.; Kastner, Sabine; Treisman, Anne
Limits to the capacity of visual short-term memory (VSTM) indicate a maximum storage of only 3 or 4 items. Recently, it has been suggested that activity in a specific part of the brain, the posterior parietal cortex (PPC), is correlated with behavioral estimates of VSTM capacity and might reflect a capacity-limited store. In three experiments that…
Full Text Available The dorsolateral prefrontal and posterior parietal cortex are two parts of a broader brain network involved in the control of cognitive functions such as working memory, spatial attention, and decision making. The two areas share many functional properties and exhibit similar patterns of activation during the execution of mental operations. However, neurophysiological experiments in non-human primates have also documented subtle differences, revealing functional specialization within the fronto-parietal network. These differences include the ability of the dorsolateral prefrontal cortex to influence memory performance, attention allocation and motor responses to a greater extent, and to resist interference by distracting stimuli. In recent years, distinct cellular and anatomical differences have been identified, offering insights into how functional specialization is achieved. This article reviews the common functions and functional differences between the dorsolateral prefrontal and posterior parietal cortex, and their underlying mechanisms.
Kaas, Jon H; Stepniewska, Iwona
Posterior parietal cortex (PPC) is an extensive region of the human brain that develops relatively late and is proportionally large compared with that of monkeys and prosimian primates. Our ongoing comparative studies have led to several conclusions about the evolution of this posterior parietal region. In early placental mammals, PPC likely was a small multisensory region much like PPC of extant rodents and tree shrews. In early primates, PPC likely resembled that of prosimian galagos, in which caudal PPC (PPCc) is visual and rostral PPC (PPCr) has eight or more multisensory domains where electrical stimulation evokes different complex motor behaviors, including reaching, hand-to-mouth, looking, protecting the face or body, and grasping. These evoked behaviors depend on connections with functionally matched domains in premotor cortex (PMC) and motor cortex (M1). Domains in each region compete with each other, and a serial arrangement of domains allows different factors to influence motor outcomes successively. Similar arrangements of domains have been retained in New and Old World monkeys, and humans appear to have at least some of these domains. The great expansion and prolonged development of PPC in humans suggest the addition of functionally distinct territories. We propose that, across primates, PMC and M1 domains are second and third levels in a number of parallel, interacting networks for mediating and selecting one type of action over others. © 2015 Wiley Periodicals, Inc.
Chan, Annie W-Y; Baker, Chris I
Observing touch has been reported to elicit activation in human primary and secondary somatosensory cortices and is suggested to underlie our ability to interpret other's behavior and potentially empathy. However, despite these reports, there are a large number of inconsistencies in terms of the precise topography of activation, the extent of hemispheric lateralization, and what aspects of the stimulus are necessary to drive responses. To address these issues, we investigated the localization and functional properties of regions responsive to observed touch in a large group of participants (n = 40). Surprisingly, even with a lenient contrast of hand brushing versus brushing alone, we did not find any selective activation for observed touch in the hand regions of somatosensory cortex but rather in superior and inferior portions of neighboring posterior parietal cortex, predominantly in the left hemisphere. These regions in the posterior parietal cortex required the presence of both brush and hand to elicit strong responses and showed some selectivity for the form of the object or agent of touch. Furthermore, the inferior parietal region showed nonspecific tactile and motor responses, suggesting some similarity to area PFG in the monkey. Collectively, our findings challenge the automatic engagement of somatosensory cortex when observing touch, suggest mislocalization in previous studies, and instead highlight the role of posterior parietal cortex. Copyright © 2015 the authors 0270-6474/15/351468-13$15.00/0.
Full Text Available Background: The pathophysiology of psychogenic movement disorders, including psychogenic tremor (PT, is only emerging. Case Report: This is a single case report of a patient who met diagnostic criteria for PT. He underwent positron emission tomography (PET of brain with 18F-deoxyglucose at resting state. His PET study showed symmetrically increased 18F-deoxyglucose uptake in both posterior medial parietal lobes. There was no corresponding abnormality on structural imaging. Discussion: Hypermetabolism of the medial aspects of posterior parietal lobes bilaterally may reflect abnormal activity of sensory integration that is important in the pathogenesis of PT. This further supports the idea that non-organic movement disorders may be associated with detectable functional brain abnormalities.
von Allmen, David Yoh; Wurmitzer, Karoline; Klaver, Peter
Developmental increases in visual short-term memory (VSTM) capacity have been associated with changes in attention processing limitations and changes in neural activity within neural networks including the posterior parietal cortex (PPC). A growing body of evidence suggests that the hippocampus plays a role in VSTM, but it is unknown whether the hippocampus contributes to the capacity increase across development. We investigated the functional development of the hippocampus and PPC in 57 children, adolescents and adults (age 8-27 years) who performed a visuo-spatial change detection task. A negative relationship between age and VSTM related activity was found in the right posterior hippocampus that was paralleled by a positive age-activity relationship in the right PPC. In the posterior hippocampus, VSTM related activity predicted individual capacity in children, whereas neural activity in the right anterior hippocampus predicted individual capacity in adults. The findings provide first evidence that VSTM development is supported by an integrated neural network that involves hippocampal and posterior parietal regions.
Peter J Fried
Full Text Available Phosphenes are commonly evoked by transcranial magnetic stimulation (TMS to study the functional organization, connectivity, and excitability of the human visual brain. For years, phosphenes have been documented only from stimulating early visual areas (V1-V3 and a handful of specialized visual regions (V4, V5/MT+ in occipital cortex. Recently, phosphenes were reported after applying TMS to a region of posterior parietal cortex involved in the top-down modulation of visuo-spatial processing. In the present study, we systematically characterized parietal phosphenes to determine if they are generated directly by local mechanisms or emerge through indirect activation of other visual areas. Using technology developed in-house to record the subjective features of phosphenes, we found no systematic differences in the size, shape, location, or frame-of-reference of parietal phosphenes when compared to their occipital counterparts. In a second experiment, discrete deactivation by 1 Hz repetitive TMS yielded a double dissociation: phosphene thresholds increased at the deactivated site without producing a corresponding change at the non-deactivated location. Overall, the commonalities of parietal and occipital phosphenes, and our ability to independently modulate their excitability thresholds, lead us to conclude that they share a common neural basis that is separate from either of the stimulated regions.
Limanowski, Jakub; Blankenburg, Felix
The brain constructs a flexible representation of the body from multisensory information. Previous work on monkeys suggests that the posterior parietal cortex (PPC) and ventral premotor cortex (PMv) represent the position of the upper limbs based on visual and proprioceptive information. Human experiments on the rubber hand illusion implicate similar regions, but since such experiments rely on additional visuo-tactile interactions, they cannot isolate visuo-proprioceptive integration. Here, we independently manipulated the position (palm or back facing) of passive human participants' unseen arm and of a photorealistic virtual 3D arm. Functional magnetic resonance imaging (fMRI) revealed that matching visual and proprioceptive information about arm position engaged the PPC, PMv, and the body-selective extrastriate body area (EBA); activity in the PMv moreover reflected interindividual differences in congruent arm ownership. Further, the PPC, PMv, and EBA increased their coupling with the primary visual cortex during congruent visuo-proprioceptive position information. These results suggest that human PPC, PMv, and EBA evaluate visual and proprioceptive position information and, under sufficient cross-modal congruence, integrate it into a multisensory representation of the upper limb in space. The position of our limbs in space constantly changes, yet the brain manages to represent limb position accurately by combining information from vision and proprioception. Electrophysiological recordings in monkeys have revealed neurons in the posterior parietal and premotor cortices that seem to implement and update such a multisensory limb representation, but this has been difficult to demonstrate in humans. Our fMRI experiment shows that human posterior parietal, premotor, and body-selective visual brain areas respond preferentially to a virtual arm seen in a position corresponding to one's unseen hidden arm, while increasing their communication with regions conveying visual
Tseng, Philip; Hsu, Tzu-Yu; Muggleton, Neil G; Tzeng, Ovid J L; Hung, Daisy L; Juan, Chi-Hung
It is commonly accepted that right posterior parietal cortex (PPC) plays an important role in updating spatial representations, directing visuospatial attention, and planning actions. However, recent studies suggest that right PPC may also be involved in processes that are more closely associated with our visual awareness as its activation level positively correlates with successful conscious change detection (Beck, D.M., Rees, G., Frith, C.D., & Lavie, N. (2001). Neural correlates of change detection and change blindness. Nature Neuroscience, 4, 645-650.). Furthermore, disruption of its activity increases the occurrences of change blindness, thus suggesting a causal role for right PPC in change detection (Beck, D.M., Muggleton, N., Walsh, V., & Lavie, N. (2006). Right parietal cortex plays a critical role in change blindness. Cerebral Cortex, 16, 712-717.). In the context of a 1-shot change detection paradigm, we applied transcranial magnetic stimulation (TMS) during different time intervals to elucidate the temporally precise involvement of PPC in change detection. While subjects attempted to detect changes between two image sets separated by a brief time interval, TMS was applied either during the presentation of picture 1 when subjects were encoding and maintaining information into visual short-term memory, or picture 2 when subjects were retrieving information relating to picture 1 and comparing it to picture 2. Our results show that change blindness occurred more often when TMS was applied during the viewing of picture 1, which implies that right PPC plays a crucial role in the processes of encoding and maintaining information in visual short-term memory. In addition, since our stimuli did not involve changes in spatial locations, our findings also support previous studies suggesting that PPC may be involved in the processes of encoding non-spatial visual information (Todd, J.J. & Marois, R. (2004). Capacity limit of visual short-term memory in human
Sestieri, Carlo; Shulman, Gordon L.; Corbetta, Maurizio
The posterior parietal cortex (PPC) is traditionally associated with attention, perceptual decision making and sensorimotor transformations, but more recent human neuroimaging studies support an additional role in episodic memory retrieval. In this Opinion article, we present a functional–anatomical model of the involvement of the PPC in memory retrieval. Parietal regions involved in perceptual attention and episodic memory are largely segregated and often show a push–pull relationship, poten...
Hutchinson, J. Benjamin; Uncapher, Melina R.; Weiner, Kevin S.; Bressler, David W.; Silver, Michael A.; Preston, Alison R.; Wagner, Anthony D.
While attention is critical for event memory, debate has arisen regarding the extent to which posterior parietal cortex (PPC) activation during episodic retrieval reflects engagement of PPC-mediated mechanisms of attention. Here, we directly examined the relationship between attention and memory, within and across subjects, using functional magnetic resonance imaging attention-mapping and episodic retrieval paradigms. During retrieval, 4 functionally dissociable PPC regions were identified. Specifically, 2 PPC regions positively tracked retrieval outcomes: lateral intraparietal sulcus (latIPS) indexed graded item memory strength, whereas angular gyrus (AnG) tracked recollection. By contrast, 2 other PPC regions demonstrated nonmonotonic relationships with retrieval: superior parietal lobule (SPL) tracked retrieval reaction time, consistent with a graded engagement of top-down attention, whereas temporoparietal junction displayed a complex pattern of below-baseline retrieval activity, perhaps reflecting disengagement of bottom-up attention. Analyses of retrieval effects in PPC topographic spatial attention maps (IPS0-IPS5; SPL1) revealed that IPS5 and SPL1 exhibited a nonmonotonic relationship with retrieval outcomes resembling that in the SPL region, further suggesting that SPL activation during retrieval reflects top-down attention. While demands on PPC attention mechanisms vary during retrieval attempts, the present functional parcellation of PPC indicates that 2 additional mechanisms (mediated by latIPS and AnG) positively track retrieval outcomes. PMID:23019246
Full Text Available The right hemispheric dominance in visuospatial attention in human brain has been well established. Converging evidence has documented that ventral posterior parietal cortex (PPC plays an important role in visuospatial attention. The role of dorsal PPC subregions, especially the superior parietal lobule (SPL in visuospatial attention is still controversial. In the current study, we used repetitive transcranial magnetic stimulation (rTMS and diffusion magnetic resonance imaging (MRI techniques to test the role of posterior SPL in visuospatial attention and to investigate the potential neuroanatomical basis for right hemisphere dominance in visuospatial function. TMS results unraveled that the right SPL predominantly mediated visuospatial attention compared to left SPL. Anatomical connections analyses between the posterior SPL and the intrahemispheric frontal subregions and the contralateral PPC revealed that right posterior SPL has stronger anatomical connections with the ipsilateral middle frontal gyrus, with the ipsilateral inferior frontal gyrus, and with contralateral PPC than that of the left posterior SPL. Furthermore, these asymmetric anatomical connections were closely related to behavioral performances. Our findings indicate that SPL plays a crucial role in regulating visuospatial attention, and dominance of visuospatial attention results from unbalanced interactions between the bilateral fronto-parietal networks and the interhemispheric parietal network.
Full Text Available The suggestion has recently been made that certain higher-order cortical areas involved in supporting multisensory representations of the body, and of the space around it, might also play a role in controlling thermoregulatory functions. Here we demonstrate that temporary interference with the function of one of these areas, the posterior parietal cortex, by repetitive transcranial magnetic stimulation, results in a decrease in limb temperature. By contrast, interference with the activity of a sensory-specific area (the primary somatosensory cortex had no effect on temperature. The results of this experiment suggest that associative multisensory brain areas might exert a top-down modulation over basic physiological control. Such a function might be part of a larger neural circuit responsible for maintaining the integrity of the body at both a homeostatic and a psychological level.
Pandya, D.N.; Seltzer, B.
By means of autoradiographic and ablation-degeneration techniques, the intrinsic cortical connections of the posterior parietal cortex in the rhesus monkey were traced and correlated with a reappraisal of cerebral architectonics. Two major rostral-to-caudal connectional sequences exist. One begins in the dorsal postcentral gyrus (area 2) and proceeds, through architectonic divisions of the superior parietal lobule (areas PE and PEc), to a cortical region on the medial surface of the parietal lobe (area PGm). This area has architectonic features similar to those of the caudal inferior parietal lobule (area PG). The second sequence begins in the ventral post/central gyrus (area 2) and passes through the rostral inferior parietal lobule (areas PG and PFG) to reach the caudal inferior parietal lobule (area PG). Both the superior parietal lobule and the rostral inferior parietal lobule also send projections to various other zones located in the parietal opercular region, the intraparietal sulcus, and the caudalmost portion of the cingulate sulcus. Areas PGm and PG, on the other hand, project to each other, to the cingulate region, to the caudalmost portion of the superior temporal gyrus, and to the upper bank of the superior temporal sulcus. Finally, a reciprocal sequence of connections, directed from caudal to rostral, links together many of the above-mentioned parietal zones. With regard to the laminar pattern of termination, the rostral-to-caudal connections are primarily distributed in the form of cortical ''columns'' while the caudal-to-rostral connections are found mainly over the first cortical cell layer
Reasoning depends on the contribution of posterior parietal cortex (PPC). But PPC is involved in many basic operations—including spatial attention, mathematical cognition, working memory, long-term memory, and language—and the nature of its contribution to reasoning is unclear. Psychological theories of the processes underlying reasoning make divergent claims about the neural systems that are likely to be involved, and better understanding the specific contribution of PPC can help to inform these theories. We set out to address several competing hypotheses, concerning the role of PPC in reasoning: (1) reasoning involves application of formal logic and is dependent on language, with PPC activation for reasoning mainly reflective of linguistic processing; (2) reasoning involves probabilistic computation and is thus dependent on numerical processing mechanisms in PPC; and (3) reasoning is built upon the representation and processing of spatial relations, and PPC activation associated with reasoning reflects spatial processing. We conducted two separate meta-analyses. First, we pooled data from our own studies of reasoning in adults, and examined activation in PPC regions of interest (ROI). Second, we conducted an automated meta-analysis using Neurosynth, in which we examined overlap between activation maps associated with reasoning and maps associated with other key functions of PPC. In both analyses, we observed reasoning-related activation concentrated in the left Inferior Parietal Lobe (IPL). Reasoning maps demonstrated the greatest overlap with mathematical cognition. Maintenance, visuospatial, and phonological processing also demonstrated some overlap with reasoning, but a large portion of the reasoning map did not overlap with the map for any other function. This evidence suggests that the PPC’s contribution to reasoning may be most closely related to its role in mathematical cognition, but that a core component of this contribution may be specific to
Full Text Available Reasoning depends on the contribution of posterior parietal cortex (PPC. But PPC is involved in many basic operations -- including spatial attention, mathematical cognition, working memory, long-term memory, and language -- and the nature of its contribution to reasoning is unclear. Psychological theories of the processes underlying reasoning make divergent claims about the neural systems that are likely to be involved, and better understanding the specific contribution of PPC can help to inform these theories. We set out to address several competing hypotheses, concerning the role of PPC in reasoning: 1 reasoning involves application of formal logic and is dependent on language, with PPC activation for reasoning mainly reflective of linguistic processing, 2 reasoning involves probabilistic computation and is thus dependent on numerical processing mechanisms in PPC, and 3 reasoning is built upon the representation and processing of spatial relations, and PPC activation associated with reasoning reflects spatial processing. We conducted two separate meta-analyses. First, we pooled data from our own studies of reasoning in adults, and examined activation in PPC regions of interest. Second, we conducted an automated meta-analysis using Neurosynth, in which we examined overlap between activation maps associated with reasoning and maps associated with other key functions of PPC. In both analyses, we observed reasoning-related activation concentrated in the left Inferior Parietal Lobe (IPL. Reasoning maps demonstrated the greatest overlap with mathematical cognition. Maintenance, visuospatial, and phonological processing also demonstrated some overlap with reasoning, but a large portion of the reasoning map did not overlap with the map for any other function. This evidence suggests that the PPC’s contribution to reasoning may be most closely related to its role in mathematical cognition, but that a core component of this contribution may be specific
Sestieri, Carlo; Shulman, Gordon L; Corbetta, Maurizio
The posterior parietal cortex (PPC) is traditionally associated with attention, perceptual decision making and sensorimotor transformations, but more recent human neuroimaging studies support an additional role in episodic memory retrieval. In this Opinion article, we present a functional-anatomical model of the involvement of the PPC in memory retrieval. Parietal regions involved in perceptual attention and episodic memory are largely segregated and often show a push-pull relationship, potentially mediated by prefrontal regions. Moreover, different PPC regions carry out specific functions during retrieval - for example, representing retrieved information, recoding this information based on task demands, or accumulating evidence for memory decisions.
Uncapher, Melina; Wagner, Anthony D.
The formation of episodic memories –– memories for life events –– is affected by attention during event processing. A leading neurobiological model of attention posits two separate yet interacting systems that depend on distinct regions in lateral posterior parietal cortex (PPC). From this dual-attention perspective, dorsal PPC is thought to support the goal-directed allocation of attention, whereas ventral PPC is thought to support reflexive orienting to information that automatically captures attention. To advance understanding of how parietal mechanisms may impact event encoding, we review functional MRI studies that document the relationship between lateral PPC activation during encoding and subsequent memory performance (e.g., later remembering or forgetting). This review reveals that (a) encoding-related activity is frequently observed in human lateral PPC, (b) increased activation in dorsal PPC is associated with later memory success, and (c) increased activation in ventral PPC predominantly correlates with later memory failure. From a dual-attention perspective, these findings suggest that allocating goal-directed attention during event processing increases the probability that the event will be remembered later, whereas the capture of reflexive attention during event processing may have negative consequences for event encoding. The prevalence of encoding-related activation in parietal cortex suggests that neurobiological models of episodic memory should consider how parietal-mediated attentional mechanisms regulate encoding. PMID:19028591
Uncapher, Melina R; Wagner, Anthony D
The formation of episodic memories--memories for life events--is affected by attention during event processing. A leading neurobiological model of attention posits two separate yet interacting systems that depend on distinct regions in lateral posterior parietal cortex (PPC). From this dual-attention perspective, dorsal PPC is thought to support the goal-directed allocation of attention, whereas ventral PPC is thought to support reflexive orienting to information that automatically captures attention. To advance understanding of how parietal mechanisms may impact event encoding, we review functional MRI studies that document the relationship between lateral PPC activation during encoding and subsequent memory performance (e.g., later remembering or forgetting). This review reveals that (a) encoding-related activity is frequently observed in human lateral PPC, (b) increased activation in dorsal PPC is associated with later memory success, and (c) increased activation in ventral PPC predominantly correlates with later memory failure. From a dual-attention perspective, these findings suggest that allocating goal-directed attention during event processing increases the probability that the event will be remembered later, whereas the capture of reflexive attention during event processing may have negative consequences for event encoding. The prevalence of encoding-related activation in parietal cortex suggests that neurobiological models of episodic memory should consider how parietal-mediated attentional mechanisms regulate encoding.
Chao, Chi-Chao; Karabanov, Anke Ninija; Paine, Rainer
There is anatomical and functional connectivity between the primary motor cortex (M1) and posterior parietal cortex (PPC) that plays a role in sensorimotor integration. In this study, we applied corticocortical paired-associative stimuli to ipsilateral PPC and M1 (parietal ccPAS) in healthy right......-handed subjects to test if this procedure could modulate M1 excitability and PPC–M1 connectivity. One hundred and eighty paired transcranial magnetic stimuli to the PPC and M1 at an interstimulus interval (ISI) of 8 ms were delivered at 0.2 Hz. We found that parietal ccPAS in the left hemisphere increased...... the excitability of conditioned left M1 assessed by motor evoked potentials (MEPs) and the input–output curve. Motor behavior assessed by the Purdue pegboard task was unchanged compared with controls. At baseline, conditioning stimuli over the left PPC potentiated MEPs from left M1 when ISI was 8 ms...
Ogawa, Kenji; Inui, Toshio
Internal monitoring or state estimation of movements is essential for human motor control to compensate for inherent delays and noise in sensorimotor loops. Two types of internal estimation of movements exist: self-generated movements, and externally generated movements. We used functional magnetic resonance imaging to investigate differences in brain activity for internal monitoring of self- versus externally generated movements during visual occlusion. Participants tracked a sinusoidally moving target with a mouse cursor. On some trials, vision of either target (externally generated) or cursor (self-generated) movement was transiently occluded, during which subjects continued tracking by estimating current position of either the invisible target or cursor on screen. Analysis revealed that both occlusion conditions were associated with increased activity in the presupplementary motor area and decreased activity in the right lateral occipital cortex compared to a control condition with no occlusion. Moreover, the right and left posterior parietal cortex (PPC) showed greater activation during occlusion of target and cursor movements, respectively. This study suggests lateralization of the PPC for internal monitoring of internally versus externally generated movements, fully consistent with previously reported clinical findings.
Myskiw, Jociane C.; Izquierdo, Iván
The posterior parietal cortex (PPC) was long viewed as just involved in the perception of spatial relationships between the body and its surroundings and of movements related to them. In recent years the PPC has been shown to participate in many other cognitive processes, among which working memory and the consolidation and retrieval of episodic memory. The neurotransmitter and other molecular processes involved have been determined to a degree in rodents. More research will no doubt determin...
Ferri, Stefania; Rizzolatti, Giacomo
Abstract The present fMRI study examined whether upper‐limb action classes differing in their motor goal are encoded by different PPC sectors. Action observation was used as a proxy for action execution. Subjects viewed actors performing object‐related (e.g., grasping), skin‐displacing (e.g., rubbing the skin), and interpersonal upper limb actions (e.g., pushing someone). Observation of the three action classes activated a three‐level network including occipito‐temporal, parietal, and premotor cortex. The parietal region common to observing all three action classes was located dorsally to the left intraparietal sulcus (DIPSM/DIPSA border). Regions specific for observing an action class were obtained by combining the interaction between observing action classes and stimulus types with exclusive masking for observing the other classes, while for regions considered preferentially active for a class the interaction was exclusively masked with the regions common to all observed actions. Left putative human anterior intraparietal was specific for observing manipulative actions, and left parietal operculum including putative human SII region, specific for observing skin‐displacing actions. Control experiments demonstrated that this latter activation depended on seeing the skin being moved and not simply on seeing touch. Psychophysiological interactions showed that the two specific parietal regions had similar connectivities. Finally, observing interpersonal actions preferentially activated a dorsal sector of left DIPSA, possibly the homologue of ventral intraparietal coding the impingement of the target person's body into the peripersonal space of the actor. These results support the importance of segregation according to the action class as principle of posterior parietal cortex organization for action observation and by implication for action execution. Hum Brain Mapp 36:3845–3866, 2015. © 2015 The Authors Human Brain Mapping Published by Wiley
Andreas A Ioannides
Full Text Available Cross-modal activity in visual cortex of blind subjects has been reported during performance of variety of non-visual tasks. A key unanswered question is through which pathways non-visual inputs are funneled to the visual cortex. Here we used tomographic analysis of single trial magnetoencephalography (MEG data recorded from one congenitally blind and two sighted subjects after stimulation of the left and right median nerves at three intensities: below sensory threshold, above sensory threshold and above motor threshold; the last sufficient to produce thumb twitching. We identified reproducible brain responses in the primary somatosensory (S1 and motor (M1 cortices at around 20 ms post-stimulus, which were very similar in sighted and blind subjects. Time-frequency analysis revealed strong 45 to 70 Hz activity at latencies of 20 to 50 ms in S1 and M1, and posterior parietal cortex Brodmann areas (BA 7 and 40, which compared to lower frequencies, were substantially more pronounced in the blind than the sighted subjects. Critically, at frequencies from α-band up to 100 Hz we found clear, strong and widespread responses in the visual cortex of the blind subject, which increased with the intensity of the somatosensory stimuli. Time-delayed mutual information (MI revealed that in blind subject the stimulus information is funneled from the early somatosensory to visual cortex through posterior parietal BA 7 and 40, projecting first to visual areas V5 and V3, and eventually V1. The flow of information through this pathway occured in stages characterized by convergence of activations into specific cortical regions. In sighted subjects, no linked activity was found that led from the somatosensory to the visual cortex through any of the studied brain regions. These results provide the first evidence from MEG that in blind subjects, tactile information is routed from primary somatosensory to occipital cortex via the posterior parietal cortex.
Ioannides, Andreas A; Liu, Lichan; Poghosyan, Vahe; Saridis, George A; Gjedde, Albert; Ptito, Maurice; Kupers, Ron
Cross-modal activity in visual cortex of blind subjects has been reported during performance of variety of non-visual tasks. A key unanswered question is through which pathways non-visual inputs are funneled to the visual cortex. Here we used tomographic analysis of single trial magnetoencephalography (MEG) data recorded from one congenitally blind and two sighted subjects after stimulation of the left and right median nerves at three intensities: below sensory threshold, above sensory threshold and above motor threshold; the last sufficient to produce thumb twitching. We identified reproducible brain responses in the primary somatosensory (S1) and motor (M1) cortices at around 20 ms post-stimulus, which were very similar in sighted and blind subjects. Time-frequency analysis revealed strong 45-70 Hz activity at latencies of 20-50 ms in S1 and M1, and posterior parietal cortex Brodmann areas (BA) 7 and 40, which compared to lower frequencies, were substantially more pronounced in the blind than the sighted subjects. Critically, at frequencies from α-band up to 100 Hz we found clear, strong, and widespread responses in the visual cortex of the blind subject, which increased with the intensity of the somatosensory stimuli. Time-delayed mutual information (MI) revealed that in blind subject the stimulus information is funneled from the early somatosensory to visual cortex through posterior parietal BA 7 and 40, projecting first to visual areas V5 and V3, and eventually V1. The flow of information through this pathway occurred in stages characterized by convergence of activations into specific cortical regions. In sighted subjects, no linked activity was found that led from the somatosensory to the visual cortex through any of the studied brain regions. These results provide the first evidence from MEG that in blind subjects, tactile information is routed from primary somatosensory to occipital cortex via the posterior parietal cortex.
Karabanov, Anke Ninija; Jin, Seung-Hyun; Joutsen, Atte
at baseline and at four time points (0, 30, 60, and 180 min) after training. For EEG, task-related power and coherence were calculated for early and late training phases. The conditioned MEP was facilitated at a 2-ms conditioning-test interval before training. However, facilitation was abolished immediately...... following training, but returned to baseline at subsequent time points. Regional EEG activity and interregional connectivity between PPC and M1 showed an initial increase during early training followed by a significant decrease in the late phases. The findings indicate that parietal-motor interactions......Interplay between posterior parietal cortex (PPC) and ipsilateral primary motor cortex (M1) is crucial during execution of movements. The purpose of the study was to determine whether functional PPC-M1 connectivity in humans can be modulated by sensorimotor training. Seventeen participants...
Leichnetz, G R
The afferent and efferent cortical and subcortical connections of the medial posterior parietal cortex (area 7m) were studied in cebus (Cebus apella) and macaque (Macaca fascicularis) monkeys using the retrograde and anterograde capabilities of the horseradish peroxidase (HRP) technique. The principal intraparietal corticocortical connections of area 7m in both cebus and macaque cases were with the ipsilateral medial bank of the intraparietal sulcus (MIP) and adjacent superior parietal lobule (area 5), inferior parietal lobule (area 7a), lateral bank of the IPS (area 7ip), caudal parietal operculum (PGop), dorsal bank of the caudal superior temporal sulcus (visual area MST), and medial prestriate cortex (including visual area PO and caudal medial lobule). Its principal frontal corticocortical connections were with the prefrontal cortex in the shoulder above the principal sulcus and the cortex in the shoulder above the superior ramus of the arcuate sulcus (SAS), the area purported to contain the smooth eye movement-related frontal eye field (FEFsem) in the cebus monkey by other investigators. There were moderate connections with the cortex in the rostral bank of the arcuate sulcus (purported to contain the saccade-related frontal eye field; FEFsac), supplementary eye field (SEF), and rostral dorsal premotor area (PMDr). Area 7m also had major connections with the cingulate cortex (area 23), particularly the ventral bank of the cingulate sulcus. The principal subcortical connections of area 7m were with the dorsal portion of the ventrolateral thalamic (VLc) nucleus, lateral posterior thalamic nucleus, lateral pulvinar, caudal mediodorsal thalamic nucleus and medial pulvinar, central lateral, central superior lateral, and central inferior intralaminar thalamic nuclei, dorsolateral caudate nucleus and putamen, middle region of the claustrum, nucleus of the diagonal band, zona incerta, pregeniculate nucleus, anterior and posterior pretectal nuclei, intermediate layer of
Grabner, Roland H; Rütsche, Bruno; Ruff, Christian C; Hauser, Tobias U
The successful acquisition of arithmetic skills is an essential step in the development of mathematical competencies and has been associated with neural activity in the left posterior parietal cortex (PPC). It is unclear, however, whether this brain region plays a causal role in arithmetic skill acquisition and whether arithmetic learning can be modulated by means of non-invasive brain stimulation of this key region. In the present study we addressed these questions by applying transcranial direct current stimulation (tDCS) over the left PPC during a short-term training that simulates the typical path of arithmetic skill acquisition (specifically the transition from effortful procedural to memory-based problem-solving strategies). Sixty participants received either anodal, cathodal or sham tDCS while practising complex multiplication and subtraction problems. The stability of the stimulation-induced learning effects was assessed in a follow-up test 24 h after the training. Learning progress was modulated by tDCS. Cathodal tDCS (compared with sham) decreased learning rates during training and resulted in poorer performance which lasted over 24 h after stimulation. Anodal tDCS showed an operation-specific improvement for subtraction learning. Our findings extend previous studies by demonstrating that the left PPC is causally involved in arithmetic learning (and not only in arithmetic performance) and that even a short-term tDCS application can modulate the success of arithmetic knowledge acquisition. Moreover, our finding of operation-specific anodal stimulation effects suggests that the enhancing effects of tDCS on learning can selectively affect just one of several cognitive processes mediated by the stimulated area. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.
Chen, Jessie; Reitzen, Shari D; Kohlenstein, Jane B; Gardner, Esther P
Studies of hand manipulation neurons in posterior parietal cortex of monkeys suggest that their spike trains represent objects by the hand postures needed for grasping or by the underlying patterns of muscle activation. To analyze the role of hand kinematics and object properties in a trained prehension task, we correlated the firing rates of neurons in anterior area 5 with hand behaviors as monkeys grasped and lifted knobs of different shapes and locations in the workspace. Trials were divided into four classes depending on the approach trajectory: forward, lateral, and local approaches, and regrasps. The task factors controlled by the animal-how and when he used the hand-appeared to play the principal roles in modulating firing rates of area 5 neurons. In all, 77% of neurons studied (58/75) showed significant effects of approach style on firing rates; 80% of the population responded at higher rates and for longer durations on forward or lateral approaches that included reaching, wrist rotation, and hand preshaping prior to contact, but only 13% distinguished the direction of reach. The higher firing rates in reach trials reflected not only the arm movements needed to direct the hand to the target before contact, but persisted through the contact, grasp, and lift stages. Moreover, the approach style exerted a stronger effect on firing rates than object features, such as shape and location, which were distinguished by half of the population. Forty-three percent of the neurons signaled both the object properties and the hand actions used to acquire them. However, the spread in firing rates evoked by each knob on reach and no-reach trials was greater than distinctions between different objects grasped with the same approach style. Our data provide clear evidence for synergies between reaching and grasping that may facilitate smooth, coordinated actions of the arm and hand.
de Vries, Paulien M.; de Jong, Bauke M.; Bohning, Daryl E.; Hinson, Vanessa K.; George, Mark S.; Leenders, Klaus L.
Objective: Clinically normal hand movement with altered cerebral activation patterns in cervical dystonia (CD) may imply cerebral adaptation. Since impaired sensorimotor integration appears to play a role in dystonia, left superior parietal cortex modulation with repetitive transcranial magnetic
Ioannides, Andreas A; Liu, Lichan; Poghosyan, Vahe
magnetoencephalography (MEG) data recorded from one congenitally blind and two sighted subjects after stimulation of the left and right median nerves at three intensities: below sensory threshold, above sensory threshold and above motor threshold; the last sufficient to produce thumb twitching. We identified...... reproducible brain responses in the primary somatosensory (S1) and motor (M1) cortices at around 20 ms post-stimulus, which were very similar in sighted and blind subjects. Time-frequency analysis revealed strong 45-70 Hz activity at latencies of 20-50 ms in S1 and M1, and posterior parietal cortex Brodmann...... of information through this pathway occurred in stages characterized by convergence of activations into specific cortical regions. In sighted subjects, no linked activity was found that led from the somatosensory to the visual cortex through any of the studied brain regions. These results provide the first...
Bolognini, Nadia; Convento, Silvia; Banco, Elisabetta; Mattioli, Flavia; Tesio, Luigi; Vallar, Giuseppe
Limb apraxia, a deficit of planning voluntary gestures, is most frequently caused by damage to the left hemisphere, where, according to an influential neurofunctional model, gestures are planned, before being executed through the motor cortex of the hemisphere contralateral to the acting hand. We used anodal transcranial direct current stimulation delivered to the left posterior parietal cortex (PPC), the right motor cortex (M1), and a sham stimulation condition, to modulate the ability of six left-brain-damaged patients with ideomotor apraxia, and six healthy control subjects, to imitate hand gestures, and to perform skilled hand movements using the left hand. Transcranial direct current stimulation delivered to the left PPC reduced the time required to perform skilled movements, and planning, but not execution, times in imitating gestures, in both patients and controls. In patients, the amount of decrease of planning times brought about by left PPC transcranial direct current stimulation was influenced by the size of the parietal lobe damage, with a larger parietal damage being associated with a smaller improvement. Of interest from a clinical perspective, left PPC stimulation also ameliorated accuracy in imitating hand gestures in patients. Instead, transcranial direct current stimulation to the right M1 diminished execution, but not planning, times in both patients and healthy controls. In conclusion, by using a transcranial stimulation approach, we temporarily improved ideomotor apraxia in the left hand of left-brain-damaged patients, showing a role of the left PPC in planning gestures. This evidence opens up novel perspectives for the use of transcranial direct current stimulation in the rehabilitation of limb apraxia. © The Author (2014). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: firstname.lastname@example.org.
Full Text Available This study aimed to elucidate electrophysiological and cortical mechanisms involved in anticipatory actions when individuals had to catch balls in free drop; specifically through quantitative electroencephalography (qEEG alpha absolute power changes. The sample was composed for 23 health subjects, both sexes, with ages varying between 25 and 40 years, absence of mental and physical illness, right handed and don't make use of any psychoactive or psychotropic substance at the time of the study. The experiment consisted of a task of catching balls in free drop. The three-way ANOVA analysis demonstrated an interaction between moment and position factors in left parietal posterior cortex (PPC (p=0.001. Through the experimental task employed, this area demonstrated a differentiated activity involving expectation, planning and preparedness in the ball's drop task.O estudo tentou elucidar mecanismos eletrofisiológicos e corticais envolvidos em ações antecipatórias quando os sujeitos testados tiveram que apreender bolas em queda livre; especificamente através de mudanças na potência absoluta na banda alfa da eletrencefalografia quantitativa (EEGq. A amostra foi composta por 23 sujeitos sadios, ambos os sexos, idade entre variando entre 25 e 40 anos, sem comprometimento físico e mental, destros, e não fazer uso de nenhuma substância psicoativa ou psicotrópicos até o momento do estudo. O experimento consistiu de uma tarefa de apreensão de bolas em queda livre. A análise three-way ANOVA demonstrou uma interação entre os fatores momento e posição no córtex parietal posterior (CPP esquerdo (p=0,001. Através da tarefa experimental empregada, esta área demonstrou uma atividade diferenciada envolvendo expectativa, planejamento e prontidão na tarefa de queda de bolas.
Megumi, Fukuda; Bahrami, Bahador; Kanai, Ryota; Rees, Geraint
The neural mechanisms underlying conscious visual perception have been extensively investigated using bistable perception paradigms. Previous functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) studies suggest that the right anterior superior parietal (r-aSPL) and the right posterior superior parietal lobule (r-pSPL) have opposite roles in triggering perceptual reversals. It has been proposed that these two areas are part of a hierarchical network whose dynamics determine perceptual switches. However, how these two parietal regions interact with each other and with the rest of the brain during bistable perception is not known. Here, we investigated such a model by recording brain activity using fMRI while participants viewed a bistable structure-from-motion stimulus. Using dynamic causal modeling (DCM), we found that resolving such perceptual ambiguity was specifically associated with reciprocal interactions between these parietal regions and V5/MT. Strikingly, the strength of bottom-up coupling between V5/MT to r-pSPL and from r-pSPL to r-aSPL predicted individual mean dominance duration. Our findings are consistent with a hierarchical predictive coding model of parietal involvement in bistable perception and suggest that visual information processing underlying spontaneous perceptual switches can be described as changes in connectivity strength between parietal and visual cortical regions. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.
Sheremata, Summer L; Somers, David C; Shomstein, Sarah
Visual short-term memory (VSTM) and attention are distinct yet interrelated processes. While both require selection of information across the visual field, memory additionally requires the maintenance of information across time and distraction. VSTM recruits areas within human (male and female) dorsal and ventral parietal cortex that are also implicated in spatial selection; therefore, it is important to determine whether overlapping activation might reflect shared attentional demands. Here, identical stimuli and controlled sustained attention across both tasks were used to ask whether fMRI signal amplitude, functional connectivity, and contralateral visual field bias reflect memory-specific task demands. While attention and VSTM activated similar cortical areas, BOLD amplitude and functional connectivity in parietal cortex differentiated the two tasks. Relative to attention, VSTM increased BOLD amplitude in dorsal parietal cortex and decreased BOLD amplitude in the angular gyrus. Additionally, the tasks differentially modulated parietal functional connectivity. Contrasting VSTM and attention, intraparietal sulcus (IPS) 1-2 were more strongly connected with anterior frontoparietal areas and more weakly connected with posterior regions. This divergence between tasks demonstrates that parietal activation reflects memory-specific functions and consequently modulates functional connectivity across the cortex. In contrast, both tasks demonstrated hemispheric asymmetries for spatial processing, exhibiting a stronger contralateral visual field bias in the left versus the right hemisphere across tasks, suggesting that asymmetries are characteristic of a shared selection process in IPS. These results demonstrate that parietal activity and patterns of functional connectivity distinguish VSTM from more general attention processes, establishing a central role of the parietal cortex in maintaining visual information. SIGNIFICANCE STATEMENT Visual short-term memory (VSTM) and
Full Text Available Recent studies suggest that action video game players exhibit superior performance in visuospatial cognitive tasks compared with non-game players. However, the neural basis underlying this visuospatial cognitive performance advantage remains largely unknown. The present human behavioral and imaging study compared gray matter volume in action video game experts and non-experts using structural magnetic resonance imaging and voxel-based morphometry analysis. The results revealed significantly larger gray matter volume in the right posterior parietal cortex in experts compared with non-experts. Furthermore, the larger gray matter volume in the right posterior parietal cortex significantly correlated with individual performance in a visual working memory task in experts. These results suggest that differences in brain structure may be linked to extensive video game play, leading to superior visuospatial cognitive performance in action video game experts.
Liang, Wei-Kuang; Juan, Chi-Hung
The right posterior parietal cortex (rPPC) has been found to be critical in shaping visual selection and distractor-induced saccade curvature in the context of predictive as well as nonpredictive visual cues by means of transcranial magnetic stimulation (TMS) interference. However, the dynamic details of how distractor-induced saccade curvatures are affected by rPPC TMS have not yet been investigated. This study aimed to elucidate the key dynamic properties that cause saccades to curve away from distractors with different degrees of curvature in various TMS and target predictability conditions. Stochastic optimal feedback control theory was used to model the dynamics of the TMS saccade data. This allowed estimation of torques, which was used to identify the critical dynamic mechanisms producing saccade curvature. The critical mechanisms of distractor-induced saccade curvatures were found to be the motor commands and torques in the transverse direction. When an unpredictable saccade target occurred with rPPC TMS, there was an initial period of greater distractor-induced torque toward the side opposite the distractor in the transverse direction, immediately followed by a relatively long period of recovery torque that brought the deviated trace back toward the target. The results imply that the mechanisms of distractor-induced saccade curvature may be comprised of two mechanisms: the first causing the initial deviation and the second bringing the deviated trace back toward the target. The pattern of the initial torque in the transverse direction revealed the former mechanism. Conversely, the later mechanism could be well explained as a consequence of the control policy in this model. To summarize, rPPC TMS increased the initial torque away from the distractor as well as the recovery torque toward the target.
Zatorre, Robert J; Halpern, Andrea R; Bouffard, Marc
Two fMRI experiments explored the neural substrates of a musical imagery task that required manipulation of the imagined sounds: temporal reversal of a melody. Musicians were presented with the first few notes of a familiar tune (Experiment 1) or its title (Experiment 2), followed by a string of notes that was either an exact or an inexact reversal. The task was to judge whether the second string was correct or not by mentally reversing all its notes, thus requiring both maintenance and manipulation of the represented string. Both experiments showed considerable activation of the superior parietal lobe (intraparietal sulcus) during the reversal process. Ventrolateral and dorsolateral frontal cortices were also activated, consistent with the memory load required during the task. We also found weaker evidence for some activation of right auditory cortex in both studies, congruent with results from previous simpler music imagery tasks. We interpret these results in the context of other mental transformation tasks, such as mental rotation in the visual domain, which are known to recruit the intraparietal sulcus region, and we propose that this region subserves general computations that require transformations of a sensory input. Mental imagery tasks may thus have both task or modality-specific components as well as components that supersede any specific codes and instead represent amodal mental manipulation.
Full Text Available Both neuropsychological and functional neuroimaging studies have identified that the posterior parietal lobe (PPL is critical for the attention function. However, the unique role of distinct parietal cortical subregions and their underlying white matter (WM remains in question. In this study, we collected both magnetic resonance imaging and diffusion tensor imaging (DTI data in normal participants, and evaluated their attention performance using attention network test (ANT, which could isolate three different attention components: alerting, orienting and executive control. Cortical thickness, surface area and DTI parameters were extracted from predefined PPL subregions and correlated with behavioural performance. Tract-based spatial statistics (TBSS was used for the voxel-wise statistical analysis. Results indicated structure-behaviour relationships on multiple levels. First, a link between the cortical thickness and WM integrity of the right inferior parietal regions and orienting performance was observed. Specifically, probabilistic tractography demonstrated that the integrity of WM connectivity between the bilateral inferior parietal lobules mediated the orienting performance. Second, the scores of executive control were significantly associated with the WM diffusion metrics of the right supramarginal gyrus. Finally, TBSS analysis revealed that alerting performance was significant correlated with the fractional anisotropy of local WM connecting the right thalamus and supplementary motor area. We conclude that distinct areas and features within PPL are associated with different components of attention. These findings could yield a more complete understanding of the nature of the PPL contribution to visuospatial attention.
Schiffino, Felipe L; Zhou, Vivian; Holland, Peter C
Within most contemporary learning theories, reinforcement prediction error, the difference between the obtained and expected reinforcer value, critically influences associative learning. In some theories, this prediction error determines the momentary effectiveness of the reinforcer itself, such that the same physical event produces more learning when its presentation is surprising than when it is expected. In other theories, prediction error enhances attention to potential cues for that reinforcer by adjusting cue-specific associability parameters, biasing the processing of those stimuli so that they more readily enter into new associations in the future. A unique feature of these latter theories is that such alterations in stimulus associability must be represented in memory in an enduring fashion. Indeed, considerable data indicate that altered associability may be expressed days after its induction. Previous research from our laboratory identified brain circuit elements critical to the enhancement of stimulus associability by the omission of an expected event, and to the subsequent expression of that altered associability in more rapid learning. Here, for the first time, we identified a brain region, the posterior parietal cortex, as a potential site for a memorial representation of altered stimulus associability. In three experiments using rats and a serial prediction task, we found that intact posterior parietal cortex function was essential during the encoding, consolidation, and retrieval of an associability memory enhanced by surprising omissions. We discuss these new results in the context of our previous findings and additional plausible frontoparietal and subcortical networks. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.
Full Text Available A cross-modal association between somatosensory tactile sensation and parietal and occipital activities during Braille reading was initially discovered in tests with blind subjects, with sighted and blindfolded healthy subjects used as controls. However, the neural background of oral stereognosis remains unclear. In the present study, we investigated whether the parietal and occipital cortices are activated during shape discrimination by the mouth using functional near-infrared spectroscopy (fNIRS. Following presentation of the test piece shape, a sham discrimination trial without the test pieces induced posterior parietal lobe (BA7, extrastriate cortex (BA18, BA19, and striate cortex (BA17 activation as compared with the rest session, while shape discrimination of the test pieces markedly activated those areas as compared with the rest session. Furthermore, shape discrimination of the test pieces specifically activated the posterior parietal cortex (precuneus/BA7, extrastriate cortex (BA18, 19, and striate cortex (BA17, as compared with sham sessions without a test piece. We concluded that oral tactile sensation is recognized through tactile/visual cross-modal substrates in the parietal and occipital cortices during shape discrimination by the mouth.
Robison, Matthew K; McGuirk, William P; Unsworth, Nash
The present study examined the relative contributions of the prefrontal cortex (PFC) and posterior parietal cortex (PPC) to visual working memory. Evidence from a number of different techniques has led to the theory that the PFC controls access to working memory (i.e., filtering), determining which information is encoded and maintained for later use whereas the parietal cortex determines how much information is held at 1 given time, regardless of relevance (i.e., capacity; McNab & Klingberg, 2008; Vogel, McCollough, & Machizawa, 2005). To test this theory, we delivered transcranial DC stimulation (tDCS) to the right PFC and right PPC and measured visual working memory capacity and filtering abilities both during and immediately following stimulation. We observed no evidence that tDCS to either the PFC or PPC significantly improved visual working memory. Although the present results did not allow us to make firm theoretical conclusions about the roles of the PFC and PPC in working memory, the results add to the growing body of literature surrounding tDCS and its associated behavioral and neurophysiological effects. (PsycINFO Database Record (c) 2017 APA, all rights reserved).
Full Text Available Past attempts to characterize the neural mechanisms of affective priming have conceptualized it in terms of classic cognitive conflict, but have not examined the neural oscillatory mechanisms of subliminal affective priming. Using behavioral and electroencephalogram (EEG time frequency (TF analysis, the current study examines the oscillatory dynamics of unconsciously triggered conflict in an emotional facial expressions version of the masked affective priming task. The results demonstrate that the power dynamics of conflict are characterized by increased midfrontal theta activity and suppressed parieto-occipital alpha activity. Across-subject and within-trial correlation analyses further confirmed this pattern. Phase synchrony and Granger causality analyses (GCAs revealed that the fronto-parietal network was involved in unconscious conflict detection and resolution. Our findings support a response conflict account of affective priming, and reveal the role of the fronto-parietal network in unconscious conflict control.
Jiang, Jun; Bailey, Kira; Xiao, Xiao
Past attempts to characterize the neural mechanisms of affective priming have conceptualized it in terms of classic cognitive conflict, but have not examined the neural oscillatory mechanisms of subliminal affective priming. Using behavioral and electroencephalogram (EEG) time frequency (TF) analysis, the current study examines the oscillatory dynamics of unconsciously triggered conflict in an emotional facial expressions version of the masked affective priming task. The results demonstrate that the power dynamics of conflict are characterized by increased midfrontal theta activity and suppressed parieto-occipital alpha activity. Across-subject and within-trial correlation analyses further confirmed this pattern. Phase synchrony and Granger causality analyses (GCAs) revealed that the fronto-parietal network was involved in unconscious conflict detection and resolution. Our findings support a response conflict account of affective priming, and reveal the role of the fronto-parietal network in unconscious conflict control.
Zhao Kunyuan; Wang Bin; Long Jinfeng; Li Lixin; Shen Xiaojun
Objective: To investigate the difference in front-parietal activation between the trained and untrained children engaged in addition and multiplication with functional magnetic resonance imaging (fMRI), and to explore the role of abacus mental calculation in brain development. Methods: Twenty-four children trained with abacus mental calculation and twelve untrained children performed mental calculation tasks including addition, multiplication and number-object control judging tasks. Blood oxygenation level dependence (BOLD) fMRI was performed when they were calculating. All data were analyzed by SPM2 (statistical parametric mapping 2) to generate the brain activation map. Results: The performance of the trained group had better correctness and shorter reaction time than that of the untrained group. The front-parietal activation between two groups had obvious difference. The activation involved less prefrontal cortex in the trained group than in the untrained group (P<0.05). The parietal activation in the trained group was mainly in the posterior superior parietal lobe/ precuneus, whereas the activation areas focused on the inferior parietal lobule in the untrained group. Conclusion: Abacus mental calculation involves multiple functional areas. and these areas may work together as a whole in processing arithmetic problems. Abacus mental calculation not only enhances the information processing in some brain areas and improves the utilization efficiency of neural resources, but also plays an important role in developing brain. (authors)
The flexible use of multiple cue relationships in spatial navigation : A comparison of water maze performance following hippocampal, medial septal, prefrontal cortex, or posterior parietal cortex lesions
Compton, DM; Griffith, HR; McDaniel, WF; Foster, RA; Davis, BK
Rats prepared with lesions of the prefrontal cortex, posterior parietal cortex, hippocampus, or medial septal area were tested for acquisition of a number of variations of the open-field water maze using a version of place learning assessment described by Eichenbaum, Stewart, and Morris (1991).
Grot, Stéphanie; Légaré, Virginie Petel; Lipp, Olivier; Soulières, Isabelle; Dolcos, Florin; Luck, David
Working memory deficits have been widely reported in schizophrenia, and may result from inefficient binding processes. These processes, and their neural correlates, remain understudied in schizophrenia. Thus, we designed an FMRI study aimed at investigating the neural correlates of both passive and active binding in working memory in schizophrenia. Nineteen patients with schizophrenia and 23 matched controls were recruited to perform a working memory binding task, in which they were instructed to memorize three letters and three spatial locations. In the passive binding condition, letters and spatial locations were directly presented as bound. Conversely, in the active binding condition, words and spatial locations were presented as separated, and participants were instructed to intentionally create associations between them. Patients exhibited a similar performance to the controls for the passive binding condition, but a significantly lower performance for the active binding. FMRI analyses revealed that this active binding deficit was related to aberrant activity in the posterior parietal cortex and the ventrolateral prefrontal cortex. This study provides initial evidence of a specific deficit for actively binding information in schizophrenia, which is linked to dysfunctions in the neural networks underlying attention, manipulation of information, and encoding strategies. Together, our results suggest that all these dysfunctions may be targets for neuromodulation interventions known to improve cognitive deficits in schizophrenia. Copyright © 2017 Elsevier B.V. All rights reserved.
Klostermann, Ellen C; Loui, Psyche; Shimamura, Arthur P
In neuroimaging studies, the left ventral posterior parietal cortex (PPC) is particularly active during memory retrieval. However, most studies have used verbal or verbalizable stimuli. We investigated neural activations associated with the retrieval of short, agrammatical music stimuli (Blackwood, 2004), which have been largely associated with right hemisphere processing. At study, participants listened to music stimuli and rated them on pleasantness. At test, participants made old/new recognition judgments with high/low confidence ratings. Right, but not left, ventral PPC activity was observed during the retrieval of these music stimuli. Thus, rather than indicating a special status of left PPC in retrieval, both right and left ventral PPC participate in memory retrieval, depending on the type of information that is to be remembered.
Phillips, Jeffrey S.; Velanova, Katerina; Wolk, David A.; Wheeler, Mark E.
Optimal memory retrieval depends not only on the fidelity of stored information, but also on the attentional state of the subject. Factors such as mental preparedness to engage in stimulus processing can facilitate or hinder memory retrieval. The current study used functional magnetic resonance imaging (fMRI) to distinguish preparatory brain activity before episodic and semantic retrieval tasks from activity associated with retrieval itself. A catch-trial imaging paradigm permitted separation...
Berryhill, Marian E.; Chein, Jason; Olson, Ingrid R.
Portions of the posterior parietal cortex (PPC) play a role in working memory (WM) yet the precise mechanistic function of this region remains poorly understood. The pure storage hypothesis proposes that this region functions as a short-lived modality-specific memory store. Alternatively, the internal attention hypothesis proposes that the PPC functions as an attention-based storage and refreshing mechanism deployable as an alternative to material-specific rehearsal. These models were tested in patients with bilateral PPC lesions. Our findings discount the pure storage hypothesis because variables indexing storage capacity and longevity were not disproportionately affected by PPC damage. Instead, our data support the internal attention account by showing that (a) normal participants tend to use a rehearsal-based WM maintenance strategy for recall tasks but not for recognition tasks; (b) patients with PPC lesions performed normally on WM tasks that relied on material-specific rehearsal strategies but poorly on WM tasks that relied on attention-based maintenance strategies and patient strategy usage could be shifted by task or instructions; (c) patients’ memory deficits extended into the long-term domain. These findings suggest that the PPC maintains or shifts internal attention among the representations of items in WM. PMID:21345344
Berryhill, Marian E; Chein, Jason; Olson, Ingrid R
Portions of the posterior parietal cortex (PPC) play a role in working memory (WM) yet the precise mechanistic function of this region remains poorly understood. The pure storage hypothesis proposes that this region functions as a short-lived modality-specific memory store. Alternatively, the internal attention hypothesis proposes that the PPC functions as an attention-based storage and refreshing mechanism deployable as an alternative to material-specific rehearsal. These models were tested in patients with bilateral PPC lesions. Our findings discount the pure storage hypothesis because variables indexing storage capacity and longevity were not disproportionately affected by PPC damage. Instead, our data support the internal attention account by showing that (a) normal participants tend to use a rehearsal-based WM maintenance strategy for recall tasks but not for recognition tasks; (b) patients with PPC lesions performed normally on WM tasks that relied on material-specific rehearsal strategies but poorly on WM tasks that relied on attention-based maintenance strategies and patient strategy usage could be shifted by task or instructions; (c) patients' memory deficits extended into the long-term domain. These findings suggest that the PPC maintains or shifts internal attention among the representations of items in WM. Copyright © 2011 Elsevier Ltd. All rights reserved.
Iramina, Keiji; Ge, Sheng; Hyodo, Akira; Hayami, Takehito; Ueno, Shoogo
In this study, we applied a transcranial magnetic stimulation (TMS) to investigate the temporal aspect for the functional processing of visual attention. Although it has been known that right posterior parietal cortex (PPC) in the brain has a role in certain visual search tasks, there is little knowledge about the temporal aspect of this area. Three visual search tasks that have different difficulties of task execution individually were carried out. These three visual search tasks are the "easy feature task," the "hard feature task," and the "conjunction task." To investigate the temporal aspect of the PPC involved in the visual search, we applied various stimulus onset asynchronies (SOAs) and measured the reaction time of the visual search. The magnetic stimulation was applied on the right PPC or the left PPC by the figure-eight coil. The results show that the reaction times of the hard feature task are longer than those of the easy feature task. When SOA=150 ms, compared with no-TMS condition, there was a significant increase in target-present reaction time when TMS pulses were applied. We considered that the right PPC was involved in the visual search at about SOA=150 ms after visual stimulus presentation. The magnetic stimulation to the right PPC disturbed the processing of the visual search. However, the magnetic stimulation to the left PPC gives no effect on the processing of the visual search.
Mohan, Hemanth; de Haan, Roel; Mansvelder, Huibert D; de Kock, Christiaan P J
Our daily life consists of a continuous interplay between incoming sensory information and outgoing motor plans. Particularly during goal-directed behavior and active exploration of the sensory environment, brain circuits are merging sensory and motor signals. This is referred to as sensorimotor
Full Text Available A recent line of work has found remarkable success in relating perceptual decision-making and the spiking activity in the macaque lateral intraparietal area (LIP. In this review, we focus on questions about the neural computations in LIP that are not answered by demonstrations of neural correlates of psychological processes. We highlight three areas of limitations in our current understanding of the precise neural computations that might underlie neural correlates of decisions: (1 empirical questions not yet answered by existing data; (2 implementation issues related to how neural circuits could actually implement the mechanisms suggested by both physiology and psychology; and (3 ecological constraints related to the use of well-controlled laboratory tasks and whether they provide an accurate window on sensorimotor computation. These issues motivate the adoption of a more general encoding-decoding framework that will be fruitful for more detailed contemplation of how neural computations in LIP relate to the formation of perceptual decisions.
Keri J. Woods
Full Text Available Number processing is a cognitive domain particularly sensitive to prenatal alcohol exposure, which relies on intact parietal functioning. Alcohol-related alterations in brain activation have been found in the parietal lobe during symbolic number processing. However, the effects of prenatal alcohol exposure on the neural correlates of non-symbolic number comparison and the numerical distance effect have not been investigated. Using functional magnetic resonance imaging (fMRI, we examined differences in brain activation associated with prenatal alcohol exposure in five parietal regions involved in number processing during a non-symbolic number comparison task with varying degrees of difficulty. fMRI results are presented for 27 Cape Colored children (6 fetal alcohol syndome (FAS/partial FAS, 5 heavily exposed (HE non-sydromal, 16 controls; mean age ± SD = 11.7 ± 1.1 years. Fetal alcohol exposure was assessed by interviewing mothers using a timeline follow-back approach. Separate subject analyses were performed in each of five regions of interest, bilateral horizontal intraparietal sulci (IPS, bilateral posterior superior parietal lobules (PSPL, and left angular gyrus (left AG, using the general linear model with predictors for number comparison and difficulty level. Mean percent signal change for each predictor was extracted for each subject for each region to examine group differences and associations with continuous measures of alcohol exposure. Although groups did not differ in performance, controls activated the right PSPL more during non-symbolic number comparison than exposed children, but this was not significant after controlling for maternal smoking, and the right IPS more than children with fetal alcohol syndrome (FAS or partial FAS. More heavily exposed children recruited the left AG to a greater extent as task difficulty increased, possibly to compensate, in part, for impairments in function in the PSPL and IPS. Notably, in non
Lee, Hongmi; Chun, Marvin M; Kuhl, Brice A
Mean fMRI activation in ventral posterior parietal cortex (vPPC) during memory encoding often negatively predicts successful remembering. A popular interpretation of this phenomenon is that vPPC reflects "off-task" processing. However, recent fMRI studies considering distributed patterns of activity suggest that vPPC actively represents encoded material. Here, we assessed the relationships between pattern-based content representations in vPPC, mean activation in vPPC, and subsequent remembering. We analyzed data from two fMRI experiments where subjects studied then recalled word-face or word-scene associations. For each encoding trial, we measured 1) mean univariate activation within vPPC and 2) the strength of face/scene information as indexed by pattern analysis. Mean activation in vPPC negatively predicted subsequent remembering, but the strength of pattern-based information in the same vPPC voxels positively predicted later memory. Indeed, univariate amplitude averaged across vPPC voxels negatively correlated with pattern-based information strength. This dissociation reflected a tendency for univariate reductions to maximally occur in voxels that were not strongly tuned for the category of encoded stimuli. These results indicate that vPPC activity patterns reflect the content and quality of memory encoding and constitute a striking example of lower univariate activity corresponding to stronger pattern-based information. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: email@example.com.
Christakou, Anastasia; Halari, Rozmin; Smith, Anna B; Ifkovits, Eve; Brammer, Mick; Rubia, Katya
Developmental functional imaging studies of cognitive control show progressive age-related increase in task-relevant fronto-striatal activation in male development from childhood to adulthood. Little is known, however, about how gender affects this functional development. In this study, we used event related functional magnetic resonance imaging to examine effects of sex, age, and their interaction on brain activation during attentional switching and interference inhibition, in 63 male and female adolescents and adults, aged 13 to 38. Linear age correlations were observed across all subjects in task-specific frontal, striatal and temporo-parietal activation. Gender analysis revealed increased activation in females relative to males in fronto-striatal areas during the Switch task, and laterality effects in the Simon task, with females showing increased left inferior prefrontal and temporal activation, and males showing increased right inferior prefrontal and parietal activation. Increased prefrontal activation clusters in females and increased parietal activation clusters in males furthermore overlapped with clusters that were age-correlated across the whole group, potentially reflecting more mature prefrontal brain activation patterns for females, and more mature parietal activation patterns for males. Gender by age interactions further supported this dissociation, revealing exclusive female-specific age correlations in inferior and medial prefrontal brain regions during both tasks, and exclusive male-specific age correlations in superior parietal (Switch task) and temporal regions (Simon task). These findings show increased recruitment of age-correlated prefrontal activation in females, and of age-correlated parietal activation in males, during tasks of cognitive control. Gender differences in frontal and parietal recruitment may thus be related to gender differences in the neurofunctional maturation of these brain regions.
Jia, Xiuqin; Liang, Peipeng; Shi, Lin; Wang, Defeng; Li, Kuncheng
In neuroimaging studies, increased task complexity can lead to increased activation in task-specific regions or to activation of additional regions. How the brain adapts to increased rule complexity during inductive reasoning remains unclear. In the current study, three types of problems were created: simple rule induction (i.e., SI, with rule complexity of 1), complex rule induction (i.e., CI, with rule complexity of 2), and perceptual control. Our findings revealed that increased activations accompany increased rule complexity in the right dorsal lateral prefrontal cortex (DLPFC) and medial posterior parietal cortex (precuneus). A cognitive model predicted both the behavioral and brain imaging results. The current findings suggest that neural activity in frontal and parietal regions is modulated by rule complexity, which may shed light on the neural mechanisms of inductive reasoning. Copyright © 2014. Published by Elsevier Ltd.
Krüger, Britta; Bischoff, Matthias; Blecker, Carlo; Langhanns, Christine; Kindermann, Stefan; Sauerbier, Isabell; Reiser, Mathias; Stark, Rudolf; Munzert, Jörn; Pilgramm, Sebastian
This study investigated whether activation within areas belonging to the action observation and imitation network reveals a linear relation to the subsequent accuracy of imitating a bimanual rhythmic movement measured via a motion capturing system. 20 participants were scanned with functional magnetic resonance imaging (fMRI) when asked to imitate observed bimanual movements either concurrently versus with a delay (2s) or simply to observe the movements without imitation. Results showed that action observation relates to activation within classic mirror-related areas. Activation patterns were more widespread when participants were asked to imitate the movement. During observation with concurrent imitation, activation in the left inferior parietal lobe (IPL) was associated negatively with imitation accuracy. During observation in the delayed imitation condition, higher subsequent imitation accuracy was coupled with higher activation in the right superior parietal lobe (SPL) and the left parietal operculum (POp). During the delayed imitation itself, a negative association between imitation accuracy and brain activation was revealed in the right ventral premotor cortex (vPMC). We conclude that the IPL is involved in online comparison and visuospatial attention processes during imitation, the SPL provides a kinesthetic blueprint during movement observation, the POp preserves body identity, and the vPMC recruits motor representations--especially when no concurrent visual guidance is possible. Copyright © 2014 Elsevier Inc. All rights reserved.
Meyer, Kristin N; Du, Feng; Parks, Emily; Hopfinger, Joseph B
Despite behavioral and electrophysiological evidence for dissociations between endogenous (voluntary) and exogenous (reflexive) attention, fMRI results have yet to consistently and clearly differentiate neural activation patterns between these two types of attention. This study specifically aimed to determine whether activity in the dorsal fronto-parietal network differed between endogenous and exogenous conditions. Participants performed a visual discrimination task in endogenous and exogenous attention conditions while undergoing fMRI scanning. Analyses revealed robust and bilateral activation throughout the dorsal fronto-parietal network for each condition, in line with many previous results. In order to investigate possible differences in the balance of neural activity within this network with greater sensitivity, a priori regions of interest (ROIs) were selected for analysis, centered on the frontal eye fields (FEF) and intraparietal sulcus (IPS) regions identified in previous studies. The results revealed a significant interaction between region, condition, and hemisphere. Specifically, in the left hemisphere, frontal areas were more active than parietal areas, but only during endogenous attention. Activity in the right hemisphere, in contrast, remained relatively consistent for these regions across conditions. Analysis of this activity over time indicates that this left-hemispheric regional imbalance is present within the FEF early, at 3-6.5 s post-stimulus presentation, whereas a regional imbalance in the exogenous condition is not evident until 6.5-8 s post-stimulus presentation. Overall, our results provide new evidence that although the dorsal fronto-parietal network is indeed associated with both types of attentional orienting, regions of the network are differentially engaged over time and across hemispheres depending on the type of attention. Copyright © 2018 Elsevier Ltd. All rights reserved.
Burra, Nicolas; Kerzel, Dirk; George, Nathalie
Gaze is one of the most important cues for human communication and social interaction. In particular, gaze contact is the most primary form of social contact and it is thought to capture attention. A very early-differentiated brain response to direct versus averted gaze has been hypothesized. Here, we used high-density electroencephalography to test this hypothesis. Topographical analysis allowed us to uncover a very early topographic modulation (40–80 ms) of event-related responses to faces with direct as compared to averted gaze. This modulation was obtained only in the condition where intact broadband faces–as opposed to high-pass or low-pas filtered faces–were presented. Source estimation indicated that this early modulation involved the posterior parietal region, encompassing the left precuneus and inferior parietal lobule. This supports the idea that it reflected an early orienting response to direct versus averted gaze. Accordingly, in a follow-up behavioural experiment, we found faster response times to the direct gaze than to the averted gaze broadband faces. In addition, classical evoked potential analysis showed that the N170 peak amplitude was larger for averted gaze than for direct gaze. Taken together, these results suggest that direct gaze may be detected at a very early processing stage, involving a parallel route to the ventral occipito-temporal route of face perceptual analysis. PMID:27880776
Full Text Available The glomerular parietal epithelial cells (PECs have aroused an increasing attention recently. The proliferation of PECs is the main feature of crescentic glomerulonephritis; besides that, in the past decade, PEC activation has been identified in several types of noninflammatory glomerulonephropathies, such as focal segmental glomerulosclerosis, diabetic glomerulopathy, and membranous nephropathy. The pathogenesis of PEC activation is poorly understood; however, a few studies delicately elucidate the potential mechanisms and signaling pathways implicated in these processes. In this review we will focus on the latest observations and concepts about PEC activation in glomerular diseases and the newest identified signaling pathways in PEC activation.
Gimbel, Sarah I; Brewer, James B
Functional imaging studies of episodic memory retrieval consistently report task-evoked and memory-related activity in the medial temporal lobe, default network and parietal lobe subregions. Associated components of memory retrieval, such as attention-shifts, search, retrieval success, and post-retrieval processing also influence regional activity, but these influences remain ill-defined. To better understand how top-down control affects the neural bases of memory retrieval, we examined how regional activity responses were modulated by task goals during recall success or failure. Specifically, activity was examined during memory suppression, recall, and elaborative recall of paired-associates. Parietal lobe was subdivided into dorsal (BA 7), posterior ventral (BA 39), and anterior ventral (BA 40) regions, which were investigated separately to examine hypothesized distinctions in sub-regional functional responses related to differential attention-to-memory and memory strength. Top-down suppression of recall abolished memory strength effects in BA 39, which showed a task-negative response, and BA 40, which showed a task-positive response. The task-negative response in default network showed greater negatively-deflected signal for forgotten pairs when task goals required recall. Hippocampal activity was task-positive and was influenced by memory strength only when task goals required recall. As in previous studies, we show a memory strength effect in parietal lobe and hippocampus, but we show that this effect is top-down controlled and sensitive to whether the subject is trying to suppress or retrieve a memory. These regions are all implicated in memory recall, but their individual activity patterns show distinct memory-strength-related responses when task goals are varied. In parietal lobe, default network, and hippocampus, top-down control can override the commonly identified effects of memory strength.
Sarah I Gimbel
Full Text Available Functional imaging studies of episodic memory retrieval consistently report task-evoked and memory-related activity in the medial temporal lobe, default network and parietal lobe subregions. Associated components of memory retrieval, such as attention-shifts, search, retrieval success, and post-retrieval processing also influence regional activity, but these influences remain ill-defined. To better understand how top-down control affects the neural bases of memory retrieval, we examined how regional activity responses were modulated by task goals during recall success or failure. Specifically, activity was examined during memory suppression, recall, and elaborative recall of paired-associates. Parietal lobe was subdivided into dorsal (BA 7, posterior ventral (BA 39, and anterior ventral (BA 40 regions, which were investigated separately to examine hypothesized distinctions in sub-regional functional responses related to differential attention-to-memory and memory strength. Top-down suppression of recall abolished memory strength effects in BA 39, which showed a task-negative response, and BA 40, which showed a task-positive response. The task-negative response in default network showed greater negatively-deflected signal for forgotten pairs when task goals required recall. Hippocampal activity was task-positive and was influenced by memory strength only when task goals required recall. As in previous studies, we show a memory strength effect in parietal lobe and hippocampus, but we show that this effect is top-down controlled and sensitive to whether the subject is trying to suppress or retrieve a memory. These regions are all implicated in memory recall, but their individual activity patterns show distinct memory-strength-related responses when task goals are varied. In parietal lobe, default network, and hippocampus, top-down control can override the commonly identified effects of memory strength.
Veronika I. Müller
Full Text Available The inferior parietal cortex (IPC is a heterogeneous region that is known to be involved in a multitude of diverse different tasks and processes, though its contribution to these often-complex functions is yet poorly understood. In a previous study we demonstrated that patients with depression failed to deactivate the left IPC during processing of congruent audiovisual information. We now found the same dysregulation (same region and condition in schizophrenia. By using task-independent (resting state and task-dependent (MACM analyses we aimed at characterizing this particular region with regard to its connectivity and function. Across both approaches, results revealed functional connectivity of the left inferior parietal seed region with bilateral IPC, precuneus and posterior cingulate cortex (PrC/PCC, medial orbitofrontal cortex (mOFC, left middle frontal (MFG as well as inferior frontal (IFG gyrus. Network-level functional characterization further revealed that on the one hand, all interconnected regions are part of a network involved in memory processes. On the other hand, sub-networks are formed when emotion, language, social cognition and reasoning processes are required. Thus, the IPC-region that is dysregulated in both depression and schizophrenia is functionally connected to a network of regions which, depending on task demands may form sub-networks. These results therefore indicate that dysregulation of left IPC in depression and schizophrenia might not only be connected to deficits in audiovisual integration, but is possibly also associated to impaired memory and deficits in emotion processing in these patient groups.
Todd, J Jay; Fougnie, Daryl; Marois, René
The right temporo-parietal junction (TPJ) is critical for stimulus-driven attention and visual awareness. Here we show that as the visual short-term memory (VSTM) load of a task increases, activity in this region is increasingly suppressed. Correspondingly, increasing VSTM load impairs the ability of subjects to consciously detect the presence of a novel, unexpected object in the visual field. These results not only demonstrate that VSTM load suppresses TPJ activity and induces inattentional blindness, but also offer a plausible neural mechanism for this perceptual deficit: suppression of the stimulus-driven attentional network.
Full Text Available Voluntary drive is crucial for motor learning, therefore we are interested in the role that motor planning plays in gait movements. In this study we examined the impact of an interactive Virtual Environment (VE feedback task on the EEG patterns during robot assisted walking. We compared walking in the VE modality to two control conditions: walking with a visual attention paradigm, in which visual stimuli were unrelated to the motor task; and walking with mirror feedback, in which participants observed their own movements. Eleven healthy participants were considered. Application of independent component analysis to the EEG revealed three independent component clusters in premotor and parietal areas showing increased activity during walking with the adaptive VE training paradigm compared to the control conditions. During the interactive VE walking task spectral power in frequency ranges 8-12Hz, 15-20Hz and 23-40Hz was significantly (p ≤ 0.05 decreased. This power decrease is interpreted as a correlate of an active cortical area. Furthermore activity in the premotor cortex revealed gait cycle related modulations significantly different (p ≤ 0.05 from baseline in the frequency range 23-40Hz during walking. These modulations were significantly (p ≤ 0.05 reduced depending on gait cycle phases in the interactive VE walking task compared to the control conditions.We demonstrate that premotor and parietal areas show increased activity during walking with the adaptive VE training paradigm, when compared to walking with mirror- and movement unrelated feedback. Previous research has related a premotor-parietal network to motor planning and motor intention. We argue that movement related interactive feedback enhances motor planning and motor intention. We hypothesize that this might improve gait recovery during rehabilitation.
Leitao, Joana; Thielscher, Axel; Lee, Hweeling
-parietal areas integrating the evidence into a decision variable that is compared to a decisional threshold. This concurrent transcranial magnetic stimulation (TMS)-fMRI study applied 10 Hz bursts of four TMS (or Sham) pulses to the intraparietal sulcus (IPS) to investigate the causal influence of IPS...... affect participants' performance accuracy, it affected how observers adjusted their response times after making an error. We therefore suggest that activation increases in superior frontal gyri for misses relative to correct responses may not be critical for signal detection performance, but rather...
Cabeza, Roberto; Mazuz, Yonatan S.; Stokes, Jared; Kragel, James E.; Woldorff, Marty G.; Ciaramelli, Elisa; Olson, Ingrid R.; Moscovitch, Morris
The specific role of different parietal regions to episodic retrieval is a topic of intense debate. According to the Attention to Memory (AtoM) model, dorsal parietal cortex (DPC) mediates top-down attention processes guided by retrieval goals, whereas ventral parietal cortex (VPC) mediates bottom-up attention processes captured by the retrieval…
Kuo, Trudy Y; Van Petten, Cyma
It is well established that source memory retrieval--remembering relationships between a core item and some additional attribute of an event--engages prefrontal cortex (PFC) more than simple item memory. In event-related potentials (ERPs), this is manifest in a late-onset difference over PFC between studied items which mandate retrieval of a second attribute, and unstudied items which can be immediately rejected. Although some sorts of attribute conjunctions are easier to remember than others, the role of source retrieval difficulty on prefrontal activity has received little attention. We examined memory for conjunctions of object shape and color when color was an integral part of the depicted object, and when monochrome objects were surrounded by colored frames. Source accuracy was reliably worse when shape and color were spatially separated, but prefrontal activity did not vary across the object-color and frame-color conditions. The insensitivity of prefrontal ERPs to this perceptual manipulation of difficulty stands in contrast to their sensitivity to encoding task: deliberate voluntary effort to integrate objects and colors during encoding reduced prefrontal activity during retrieval, but perceptual organization of stimuli did not. The amplitudes of ERPs over parietal cortex were larger for frame-color than object-color stimuli during both study and test phases of the memory task. Individual variability in parietal ERPs was strongly correlated with memory accuracy, which we suggest reflects a contribution of visual working memory to long-term memory. We discuss multiple bottlenecks for source memory performance.
Full Text Available Background: Cognitive functions progressively deteriorate during aging and neurodegenerative diseases. The present study aims at investigating differences in working memory performance as well as functional brain changes during the earliest stages of cognitive decline in health elderly individuals. Methods: 62 elderly individuals (41 females, including 41 controls (35 females and 21 middle cognitive impairment subjects (6 females, underwent neuropsychological assessment at baseline and an fMRI examination in a N-back paradigm contrasting 2-back vs. 0-back condition. Upon a 18 months follow-up, we identified stable controls (sCON with preserved cognition and deteriorating controls (dCON with -1SD decrease of performances in at least two neuropsychological tests. Data analyses included accuracy and reaction time (RT for the 2-back condition and general linear model (GLM for the fMRI sequence. Results: At the behavioral level, sCON and dCON performed better than MCI in terms of accuracy and reaction time. At the brain level, functional differences in regions of the fronto-parietal network (FPN and of the Default Mode Network (DFM were observed. Significantly lower neural activations in the bilateral inferior and middle frontal gyri were found in MCI versus both dCON / sCON and for dCON versus sCON. Significantly increased activations in the anterior cingulate cortex and posterior cingulate cortex and bilateral insula were found in MCI versus both dCON / sCON and in dCON versus sCON. Conclusion: The present study suggests that brain functional changes in FPN and DMN anticipate differences in cognitive performance in healthy elderly individuals with subsequent subtle cognitive decline.
Pesaran, B; Sahami, M; Mitra, P; Andersen, R A
A number of cortical structures are reported to have elevated single unit firing rates sustained throughout the memory period of a working memory task. How the nervous system forms and maintains these memories is unknown but reverberating neuronal network activity is thought to be important. We studied the temporal structure of single unit (SU) activity and simultaneously recorded local field potential (LFP) activity from area LIP in the inferior parietal lobe of two awake macaques during a memory-saccade task. Using multitaper techniques for spectral analysis, which play an important role in obtaining the present results, we find elevations in spectral power in a 50--90 Hz (gamma) frequency band during the memory period in both SU and LFP activity. The activity is tuned to the direction of the saccade providing evidence for temporal structure that codes for movement plans during working memory. We also find SU and LFP activity are coherent during the memory period in the 50--90 Hz gamma band and no consisten...
Holderied, Alexander; Romoli, Simone; Eberhard, Jonathan; Konrad, Lukas A; Devarapu, Satish K; Marschner, Julian A; Müller, Susanna; Anders, Hans-Joachim
The metabolic and hemodynamic alterations in diabetes activate podocytes to increase extracellular matrix (ECM) production, leading to thickening of the glomerular basement membrane (GBM). We hypothesized that diabetes would activate parietal epithelial cells (PECs) in a similar manner and cause thickening of Bowman's capsules. Periodic acid Schiff staining of human kidney biopsies of 30 patients with diabetic nephropathy (DN) revealed a significantly thicker Bowman's capsule as compared with 20 non-diabetic controls. The average thickness was 4.55±0.21 μm in the group of patients with DN compared with 2.92±0.21 μm in the group of non-diabetic controls (PBowman's capsule showed strong association with CD44-positive PECs. In summary, metabolic alterations in diabetes activate PECs to increase the expression and secretion of Bowman's capsule proteins. This process may contribute to the thickening of the Bowman's capsule, similar to the thickening of the GBM that is driven by activated podocytes. These data may also imply that activated PECs contribute to ECM production once they migrate to the glomerular tuft, a process resulting in glomerular scaring, for example, in diabetic glomerulosclerosis.
Zhang, Ying; Whitfield-Gabrieli, Susan; Christodoulou, Joanna A.; Gabrieli, John D. E.
Reading requires the extraction of letter shapes from a complex background of text, and an impairment in visual shape extraction would cause difficulty in reading. To investigate the neural mechanisms of visual shape extraction in dyslexia, we used functional magnetic resonance imaging (fMRI) to examine brain activation while adults with or without dyslexia responded to the change of an arrow’s direction in a complex, relative to a simple, visual background. In comparison to adults with typical reading ability, adults with dyslexia exhibited opposite patterns of atypical activation: decreased activation in occipital visual areas associated with visual perception, and increased activation in frontal and parietal regions associated with visual attention. These findings indicate that dyslexia involves atypical brain organization for fundamental processes of visual shape extraction even when reading is not involved. Overengagement in higher-order association cortices, required to compensate for underengagment in lower-order visual cortices, may result in competition for top-down attentional resources helpful for fluent reading. PMID:23825653
Peters, Benjamin; Kaiser, Jochen; Rahm, Benjamin; Bledowski, Christoph
Visual attention enables observers to select behaviorally relevant information based on spatial locations, features, or objects. Attentional selection is not limited to physically present visual information, but can also operate on internal representations maintained in working memory (WM) in service of higher-order cognition. However, only little is known about whether attention to WM contents follows the same principles as attention to sensory stimuli. To address this question, we investigated in humans whether the typically observed effects of object-based attention in perception are also evident for object-based attentional selection of internal object representations in WM. In full accordance with effects in visual perception, the key behavioral and neuronal characteristics of object-based attention were observed in WM. Specifically, we found that reaction times were shorter when shifting attention to memory positions located on the currently attended object compared with equidistant positions on a different object. Furthermore, functional magnetic resonance imaging and multivariate pattern analysis of visuotopic activity in visual (areas V1-V4) and parietal cortex revealed that directing attention to one position of an object held in WM also enhanced brain activation for other positions on the same object, suggesting that attentional selection in WM activates the entire object. This study demonstrated that all characteristic features of object-based attention are present in WM and thus follows the same principles as in perception. Copyright © 2015 the authors 0270-6474/15/353360-10$15.00/0.
Ferrarelli, Fabio; Smith, Richard; Dentico, Daniela; Riedner, Brady A.; Zennig, Corinna; Benca, Ruth M.; Lutz, Antoine; Davidson, Richard J.; Tononi, Giulio
Over the past several years meditation practice has gained increasing attention as a non-pharmacological intervention to provide health related benefits, from promoting general wellness to alleviating the symptoms of a variety of medical conditions. However, the effects of meditation training on brain activity still need to be fully characterized. Sleep provides a unique approach to explore the meditation-related plastic changes in brain function. In this study we performed sleep high-density electroencephalographic (hdEEG) recordings in long-term meditators (LTM) of Buddhist meditation practices (approximately 8700 mean hours of life practice) and meditation naive individuals. We found that LTM had increased parietal-occipital EEG gamma power during NREM sleep. This increase was specific for the gamma range (25–40 Hz), was not related to the level of spontaneous arousal during NREM and was positively correlated with the length of lifetime daily meditation practice. Altogether, these findings indicate that meditation practice produces measurable changes in spontaneous brain activity, and suggest that EEG gamma activity during sleep represents a sensitive measure of the long-lasting, plastic effects of meditative training on brain function. PMID:24015304
Tachibana, Atsumichi; Noah, J Adam; Bronner, Shaw; Ono, Yumie; Onozuka, Minoru
Using functional near infrared spectroscopy (fNIRS) we studied how playing a dance video game employs coordinated activation of sensory-motor integration centers of the superior parietal lobe (SPL) and superior temporal gyrus (STG). Subjects played a dance video game, in a block design with 30s of activity alternating with 30s of rest, while changes in oxy-hemoglobin (oxy-Hb) levels were continuously measured. The game was modified to compare difficult (4-arrow), simple (2-arrow), and stepping conditions. Oxy-Hb levels were greatest with increased task difficulty. The quick-onset, trapezoidal time-course increase in SPL oxy-Hb levels reflected the on-off neuronal response of spatial orienting and rhythmic motor timing that were required during the activity. Slow-onset, bell-shaped increases in oxy-Hb levels observed in STG suggested the gradually increasing load of directing multisensory information to downstream processing centers associated with motor behavior and control. Differences in temporal relationships of SPL and STG oxy-Hb concentration levels may reflect the functional roles of these brain structures during the task period. NIRS permits insights into temporal relationships of cortical hemodynamics during real motor tasks. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.
Daitch, Amy L.; Foster, Brett L.; Schrouff, Jessica; Rangarajan, Vinitha; Kaşikçi, Itır; Gattas, Sandra; Parvizi, Josef
Brain areas within the lateral parietal cortex (LPC) and ventral temporal cortex (VTC) have been shown to code for abstract quantity representations and for symbolic numerical representations, respectively. To explore the fast dynamics of activity within each region and the interaction between them, we used electrocorticography recordings from 16 neurosurgical subjects implanted with grids of electrodes over these two regions and tracked the activity within and between the regions as subjects performed three different numerical tasks. Although our results reconfirm the presence of math-selective hubs within the VTC and LPC, we report here a remarkable heterogeneity of neural responses within each region at both millimeter and millisecond scales. Moreover, we show that the heterogeneity of response profiles within each hub mirrors the distinct patterns of functional coupling between them. Our results support the existence of multiple bidirectional functional loops operating between discrete populations of neurons within the VTC and LPC during the visual processing of numerals and the performance of arithmetic functions. These findings reveal information about the dynamics of numerical processing in the brain and also provide insight into the fine-grained functional architecture and connectivity within the human brain. PMID:27821758
Lebon, Florent; Horn, Ulrike; Domin, Martin; Lotze, Martin
Motor imagery (MI) is the mental simulation of action frequently used by professionals in different fields. However, with respect to performance, well-controlled functional imaging studies on MI training are sparse. We investigated changes in fMRI representation going along with performance changes of a finger sequence (error and velocity) after MI training in 48 healthy young volunteers. Before training, we tested the vividness of kinesthetic and visual imagery. During tests, participants were instructed to move or to imagine moving the fingers of the right hand in a specific order. During MI training, participants repeatedly imagined the sequence for 15 min. Imaging analysis was performed using a full-factorial design to assess brain changes due to imagery training. We also used regression analyses to identify those who profited from training (performance outcome and gain) with initial imagery scores (vividness) and fMRI activation magnitude during MI at pre-test (MI pre ). After training, error rate decreased and velocity increased. We combined both parameters into a common performance index. FMRI activation in the left inferior parietal lobe (IPL) was associated with MI and increased over time. In addition, fMRI activation in the right IPL during MI pre was associated with high initial kinesthetic vividness. High kinesthetic imagery vividness predicted a high performance after training. In contrast, occipital activation, associated with visual imagery strategies, showed a negative predictive value for performance. Our data echo the importance of high kinesthetic vividness for MI training outcome and consider IPL as a key area during MI and through MI training. © 2018 Wiley Periodicals, Inc.
Verleger, Rolf; Möller, Friderike; Kuniecki, Michal
) either as effective or as sham stimulation. In two experiments, either one of these two factors, hemisphere and effectiveness of rTMS, was varied within or between participants. Again, T2 was much better identified in the left than in the right visual field. This advantage of the left visual field......In the present task, series of visual stimuli are rapidly presented left and right, containing two target stimuli, T1 and T2. In previous studies, T2 was better identified in the left than in the right visual field. This advantage of the left visual field might reflect dominance exerted...... by the right over the left hemisphere. If so, then repetitive transcranial magnetic stimulation (rTMS) to the right parietal cortex might release the left hemisphere from right-hemispheric control, thereby improving T2 identification in the right visual field. Alternatively or additionally, the asymmetry in T2...
Royal, Isabelle; Vuvan, Dominique T.; Zendel, Benjamin Rich; Robitaille, Nicolas; Schönwiesner, Marc; Peretz, Isabelle
Pitch discrimination tasks typically engage the superior temporal gyrus and the right inferior frontal gyrus. It is currently unclear whether these regions are equally involved in the processing of incongruous notes in melodies, which requires the representation of musical structure (tonality) in addition to pitch discrimination. To this aim, 14 participants completed two tasks while undergoing functional magnetic resonance imaging, one in which they had to identify a pitch change in a series of non-melodic repeating tones and a second in which they had to identify an incongruous note in a tonal melody. In both tasks, the deviants activated the right superior temporal gyrus. A contrast between deviants in the melodic task and deviants in the non-melodic task (melodic > non-melodic) revealed additional activity in the right inferior parietal lobule. Activation in the inferior parietal lobule likely represents processes related to the maintenance of tonal pitch structure in working memory during pitch discrimination. PMID:27195523
McDermott, Kathleen B; Gilmore, Adrian W; Nelson, Steven M; Watson, Jason M; Ojemann, Jeffrey G
Neuroimaging investigations of human memory encoding and retrieval have revealed that multiple regions of parietal cortex contribute to memory. Recently, a sparse network of regions within parietal cortex has been identified using resting state functional connectivity (MRI techniques). The regions within this network exhibit consistent task-related responses during memory formation and retrieval, leading to its being called the parietal memory network (PMN). Among its signature patterns are: deactivation during initial experience with an item (e.g., encoding); activation during subsequent repetitions (e.g., at retrieval); greater activation for successfully retrieved familiar words than novel words (e.g., hits relative to correctly-rejected lures). The question of interest here is whether novel words that are subjectively experienced as having been recently studied would elicit PMN activation similar to that of hits. That is, we compared old items correctly recognized to two types of novel items on a recognition test: those correctly identified as new and those incorrectly labeled as old due to their strong associative relation to the studied words (in the DRM false memory protocol). Subjective oldness plays a strong role in driving activation, as hits and false alarms activated similarly (and greater than correctly-rejected lures). Copyright © 2016 Elsevier Ltd. All rights reserved.
Aichhorn, Markus; Perner, Josef; Weiss, Benjamin; Kronbichler, Martin; Staffen, Wolfgang; Ladurner, Gunther
By combining the false belief (FB) and photo (PH) vignettes to identify theory-of-mind areas with the false sign (FS) vignettes, we re-establish the functional asymmetry between the left and right temporo-parietal junction (TPJ). The right TPJ (TPJ-R) is specially sensitive to processing belief information, whereas the left TPJ (TPJ-L) is equally…
Cuppoletti, J; Baker, A M; Malinowska, D H
HCl secretion across mammalian gastric parietal cell apical membrane may involve Cl- channels. H(+)-K(+)-ATPase-containing membranes isolated from gastric mucosa of histamine-stimulated rabbits were fused to planar lipid bilayers. Channels were recorded with symmetric 800 mM CsCl solutions, pH 7.4. A linear current-voltage (I-V) relationship was obtained, and conductance was 28 +/- 1 pS at 800 mM CsCl. Conductance was 6.9 +/- 2 pS at 150 mM CsCl. Reversal potential was +22 mV with a fivefold cis-trans CsCl concentration gradient, indicating that the channel was anion selective with a discrimination ratio of 6:1 for Cl- over Cs+. Anion selectivity of the channel was I- > Cl- > or = Br- > NO3-, and gluconate was impermeant. Channels obtained at pH 7.4 persisted when pH of medium bathing the trans side of the bilayer (pHtrans) was reduced to pH 3, without a change in conductance, linearity of I-V relationship, or ion selectivity. In contrast, asymmetric reduction of pH of medium bathing the cis side of the bilayer from 7.4 to 3 always resulted in loss of channel activity. At pH 7.4, open probability (Po) of the channel was voltage dependent, i.e., predominantly open at +80 mV but mainly closed at -80 mV. In contrast, with low pHtrans, channel Po at -80 mV was increased 3.5-fold. The Cl- channel was Ca2+ indifferent. In absence of ionophores, ion selectivity for support of H(+)-K(+)-ATPase activity and H+ transport was consistent with that exhibited by the channel and could be limited by substitution with NO3-, whereas maximal H(+)-K(+)-ATPase activity was indifferent to anion present, demonstrating that anion transport can be rate limiting. Cl- channels with similar characteristics (conductance, linear I-V relationship, and ion selectivity) were also present in H(+)-K(+)-ATPase-containing vesicles isolated from resting (cimetidine-treated) gastric mucosa, exhibiting at -80 mV a pH-independent approximately 3.5-fold lower Po than stimulated vesicle channels. At -80 m
Diwadkar, V A; Carpenter, P A; Just, M A
Functional MRI was used to determine how the constituents of the cortical network subserving dynamic spatial working memory respond to two types of increases in task complexity. Participants mentally maintained the most recent location of either one or three objects as the three objects moved discretely in either a two- or three-dimensional array. Cortical activation in the dorsolateral prefrontal (DLPFC) and the parietal cortex increased as a function of the number of object locations to be maintained and the dimensionality of the display. An analysis of the response characteristics of the individual voxels showed that a large proportion were activated only when both the variables imposed the higher level of demand. A smaller proportion were activated specifically in response to increases in task demand associated with each of the independent variables. A second experiment revealed the same effect of dimensionality in the parietal cortex when the movement of objects was signaled auditorily rather than visually, indicating that the additional representational demands induced by 3-D space are independent of input modality. The comodulation of activation in the prefrontal and parietal areas by the amount of computational demand suggests that the collaboration between areas is a basic feature underlying much of the functionality of spatial working memory. Copyright 2000 Academic Press.
The parietal association cortex comprises the superior and inferior parietal lobules, the precuneus and the cortices in the intraparietal, parietooccipital and lunate sulci. By processing somatic, visual, acoustic and vestibular sensory information, the parietal association cortex plays a pivotal role in spatial cognition and motor control of the eyes and the extremities. Sensory information from the primary and secondary somatosensory areas enters the superior parietal lobule and is transferred to the inferior parietal lobule. Visual information is processed through the dorsal visual pathway and it reaches the inferior parietal lobule, the intraparietal sulcus and the precuneus. Acoustic information is transferred posteriorly from the primary acoustic area, and it reaches the posterior region of the inferior parietal lobule. The areas in the intraparietal sulcus project to the premotor area, the frontal eye fields, and the prefrontal area. These areas are involved in the control of ocular movements, reaching and grasping of the upper extremities, and spatial working memory. The posterior region of the inferior parietal lobule and the precuneus both project either directly, or indirectly via the posterior cingulate gyrus, to the parahippocampal and entorhinal cortices. Both these areas are strongly associated with hippocampal functions for long-term memory formation.
Park, Hyojin; Lee, Dong Soo; Kang, Eunjoo; Kang, Hyejin; Hahm, Jarang; Kim, June Sic; Chung, Chun Kee; Jensen, Ole
In our daily lives, we are confronted with a large amount of information. Because only a small fraction can be encoded in long-term memory, the brain must rely on powerful mechanisms to filter out irrelevant information. To understand the neuronal mechanisms underlying the gating of information into long-term memory, we employed a paradigm where the encoding was directed by a "Remember" or a "No-Remember" cue. We found that posterior alpha activity increased prior to the "No-Remember" stimuli, whereas it decreased prior to the "Remember" stimuli. The sources were localized in the parietal cortex included in the dorsal attention network. Subjects with a larger cue-modulation of the alpha activity had better memory for the to-be-remembered items. Interestingly, alpha activity reflecting successful inhibition following the "No-Remember" cue was observed in the frontal midline structures suggesting preparatory inhibition was mediated by anterior parts of the dorsal attention network. During the presentation of the memory items, there was more gamma activity for the "Remember" compared to the "No-Remember" items in the same regions. Importantly, the anticipatory alpha power during cue predicted the gamma power during item. Our findings suggest that top-down controlled alpha activity reflects attentional inhibition of sensory processing in the dorsal attention network, which then finally gates information to long-term memory. This gating is achieved by inhibiting the processing of visual information reflected by neuronal synchronization in the gamma band. In conclusion, the functional architecture revealed by region-specific changes in the alpha activity reflects attentional modulation which has consequences for long-term memory encoding. Copyright © 2014 Wiley Periodicals, Inc.
Battelli, Lorella; Alvarez, George A.; Carlson, Thomas; Pascual-Leone, Alvaro
Interhemispheric competition between homologous areas in the human brain is believed to be involved in a wide variety of human behaviors from motor activity to visual perception and particularly attention. For example, patients with lesions in the posterior parietal cortex are unable to selectively track objects in the contralesional side of…
Liang, Peipeng; Jia, Xiuqin; Taatgen, Niels A; Borst, Jelmer P; Li, Kuncheng
Numerical inductive reasoning refers to the process of identifying and extrapolating the rule involved in numeric materials. It is associated with calculation, and shares the common activation of the fronto-parietal regions with calculation, which suggests that numerical inductive reasoning may correspond to a general calculation process. However, compared with calculation, rule identification is critical and unique to reasoning. Previous studies have established the central role of the fronto-parietal network for relational integration during rule identification in numerical inductive reasoning. The current question of interest is whether numerical inductive reasoning exclusively corresponds to calculation or operates beyond calculation, and whether it is possible to distinguish between them based on the activity pattern in the fronto-parietal network. To directly address this issue, three types of problems were created: numerical inductive reasoning, calculation, and perceptual judgment. Our results showed that the fronto-parietal network was more active in numerical inductive reasoning which requires more exchanges between intermediate representations and long-term declarative knowledge during rule identification. These results survived even after controlling for the covariates of response time and error rate. A computational cognitive model was developed using the cognitive architecture ACT-R to account for the behavioral results and brain activity in the fronto-parietal network.
Full Text Available Previous studies have shown that multisensory stimuli can contribute to attention control. Here we investigate whether irrelevant audio-visual stimuli can affect the processing of subsequent visual targets, in the absence of any direct bottom-up signals generated by low-level sensory changes and any goal-related associations between the multisensory stimuli and the visual targets. Each trial included two pictures (cat/dog, one in each visual hemifield, and a central sound that was semantically congruent with one of the two pictures (i.e. either meow or woof sound. These irrelevant audio-visual stimuli were followed by a visual target that appeared either where the congruent or the incongruent picture had been presented (valid/invalid trials. The visual target was a Gabor patch requiring an orientation discrimination judgment, allowing us to uncouple the visual task from the audio-visual stimuli. Behaviourally we found lower performance for invalid than valid trials, but only when the task demands were high (Gabor target presented together with a Gabor distractor vs. Gabor target alone. The fMRI analyses revealed greater activity for invalid than for valid trials in the dorsal and the ventral fronto-parietal attention networks. The dorsal network was recruited irrespective of task demands, while the ventral network was recruited only when task demands were high and target discrimination required additional top-down control. We propose that crossmodal semantic congruence generates a processing bias associated with the location of congruent picture, and that the presentation of the visual target on the opposite side required updating these processing priorities. We relate the activation of the attention networks to these updating operations. We conclude that the fronto-parietal networks mediate the influence of crossmodal semantic congruence on visuo-spatial processing, even in the absence of any low-level sensory cue and any goal-driven task
Morita, Tomoyo; Saito, Daisuke N; Ban, Midori; Shimada, Koji; Okamoto, Yuko; Kosaka, Hirotaka; Okazawa, Hidehiko; Asada, Minoru; Naito, Eiichi
We recently reported that right-side dominance of the inferior parietal lobule (IPL) in self-body recognition (proprioceptive illusion) task emerges during adolescence in typical human development. Here, we extend this finding by demonstrating that functional lateralization to the right IPL also develops during adolescence in another self-body (specifically a self-face) recognition task. We collected functional magnetic resonance imaging (fMRI) data from 60 right-handed healthy children (8-11 years), adolescents (12-15 years), and adults (18-23 years; 20 per group) while they judged whether a presented face was their own (Self) or that of somebody else (Other). We also analyzed fMRI data collected while they performed proprioceptive illusion task. All participants performed self-face recognition with high accuracy. Among brain regions where self-face-related activity (Self vs. Other) developed, only right IPL activity developed predominantly for self-face processing, with no substantial involvement in other-face processing. Adult-like right-dominant use of IPL emerged during adolescence, but was not yet present in childhood. Adult-like common activation between the tasks also emerged during adolescence. Adolescents showing stronger right-lateralized IPL activity during illusion also showed this during self-face recognition. Our results suggest the importance of the right IPL in neuronal processing of information associated with one's own body in typically developing humans.
Elman, Jeremy A; Cohn-Sheehy, Brendan I; Shimamura, Arthur P
In fMRI analyses, the posterior parietal cortex (PPC) is particularly active during the successful retrieval of episodic memory. To delineate the neural correlates of episodic retrieval more succinctly, we compared retrieval of recently learned spatial locations (photographs of buildings) with retrieval of previously familiar locations (photographs of familiar campus buildings). Episodic retrieval of recently learned locations activated a circumscribed region within the ventral PPC (anterior angular gyrus and adjacent regions in the supramarginal gyrus) as well as medial PPC regions (posterior cingulated gyrus and posterior precuneus). Retrieval of familiar locations activated more posterior regions in the ventral PPC (posterior angular gyrus, LOC) and more anterior regions in the medial PPC (anterior precuneus and retrosplenial cortex). These dissociable effects define more precisely PPC regions involved in the retrieval of recent, contextually bound information as opposed to regions involved in other processes, such as visual imagery, scene reconstruction, and self-referential processing. Copyright © 2012 Elsevier Ltd. All rights reserved.
Morita, Tomoyo; Saito, Daisuke N; Ban, Midori; Shimada, Koji; Okamoto, Yuko; Kosaka, Hirotaka; Okazawa, Hidehiko; Asada, Minoru; Naito, Eiichi
Proprioception is somatic sensation that allows us to sense and recognize position, posture, and their changes in our body parts. It pertains directly to oneself and may contribute to bodily awareness. Likewise, one's face is a symbol of oneself, so that visual self-face recognition directly contributes to the awareness of self as distinct from others. Recently, we showed that right-hemispheric dominant activity in the inferior fronto-parietal cortices, which are connected by the inferior branch of the superior longitudinal fasciculus (SLF III), is associated with proprioceptive illusion (awareness), in concert with sensorimotor activity. Herein, we tested the hypothesis that visual self-face recognition shares brain regions active during proprioceptive illusion in the right inferior fronto-parietal SLF III network. We scanned brain activity using functional magnetic resonance imaging while twenty-two right-handed healthy adults performed two tasks. One was a proprioceptive illusion task, where blindfolded participants experienced a proprioceptive illusion of right hand movement. The other was a visual self-face recognition task, where the participants judged whether an observed face was their own. We examined whether the self-face recognition and the proprioceptive illusion commonly activated the inferior fronto-parietal cortices connected by the SLF III in a right-hemispheric dominant manner. Despite the difference in sensory modality and in the body parts involved in the two tasks, both tasks activated the right inferior fronto-parietal cortices, which are likely connected by the SLF III, in a right-side dominant manner. Here we discuss possible roles for right inferior fronto-parietal activity in bodily awareness and self-awareness. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.
Liang, Peipeng; Jia, Xiuqin; Taatgen, Niels A; Borst, Jelmer P; Li, Kuncheng
Numerical inductive reasoning refers to the process of identifying and extrapolating the rule involved in numeric materials. It is associated with calculation, and shares the common activation of the fronto-parietal regions with calculation, which suggests that numerical inductive reasoning may
Schurz, M.; Tholen, M.G.; Perner, J.; Mars, R.B.; Sallet, J.
In this quantitative review, we specified the anatomical basis of brain activity reported in the Temporo-Parietal Junction (TPJ) in Theory of Mind (ToM) research. Using probabilistic brain atlases, we labeled TPJ peak coordinates reported in the literature. This was carried out for four different
Firdaus Fabrice Hannanu
In subacute stroke, fMRI brain activity related to passive movement measured in a sensorimotor network defined by activity during voluntary movement predicted motor recovery better than baseline motor-FMS alone. Furthermore, fMRI sensorimotor network activity measures considered alone allowed excellent clinical recovery prediction and may provide reliable biomarkers for assessing new therapies in clinical trial contexts. Our findings suggest that neural reorganization related to motor recovery from moderate to severe stroke results from balanced changes in ipsilesional MI (BA4a and a set of phylogenetically more archaic sensorimotor regions in the ventral sensorimotor trend, in which OP1 and OP4 processes may complement the ipsilesional dorsal motor cortex in achieving compensatory sensorimotor recovery.
Full Text Available In an uncertain environment, probabilities are key to predicting future events and making adaptive choices. However, little is known about how humans learn such probabilities and where and how they are encoded in the brain, especially when they concern more than two outcomes. During functional magnetic resonance imaging (fMRI, young adults learned the probabilities of uncertain stimuli through repetitive sampling. Stimuli represented payoffs and participants had to predict their occurrence to maximize their earnings. Choices indicated loss and risk aversion but unbiased estimation of probabilities. BOLD response in medial prefrontal cortex and angular gyri increased linearly with the probability of the currently observed stimulus, untainted by its value. Connectivity analyses during rest and task revealed that these regions belonged to the default mode network. The activation of past outcomes in memory is evoked as a possible mechanism to explain the engagement of the default mode network in probability learning. A BOLD response relating to value was detected only at decision time, mainly in striatum. It is concluded that activity in inferior parietal and medial prefrontal cortex reflects the amount of evidence accumulated in favor of competing and uncertain outcomes.
Tyler, Sarah C; Dasgupta, Samhita; Agosta, Sara; Battelli, Lorella; Grossman, Emily D
Perception of natural experiences requires allocation of attention towards features, objects, and events that are moving and changing over time. This allocation of attention is controlled by large-scale brain networks that, when damaged, cause widespread cognitive deficits. In particular, damage to ventral parietal cortex (right lateralized TPJ, STS, supramarginal and angular gyri) is associated with failures to selectively attend to and isolate features embedded within rapidly changing visual sequences (Battelli, Pascual-Leone, & Cavanagh, 2007; Husain, Shapiro, Martin, & Kennard, 1997). In this study, we used fMRI to investigate the neural activity and functional connectivity of intact parietal cortex while typical subjects judged the relative onsets and offsets of rapidly flickering tokens (a phase discrimination task in which right parietal patients are impaired). We found two regions in parietal cortex correlated with task performance: a bilateral posterior TPJ (pTPJ) and an anterior right-lateralized TPJ (R aTPJ). Both regions were deactivated when subjects engaged in the task but showed different patterns of functional connectivity. The bilateral pTPJ was strongly connected to nodes within the default mode network (DMN) and the R aTPJ was connected to the attention network. Accurate phase discriminations were associated with increased functional correlations between sensory cortex (hMT+) and the bilateral pTPJ, whereas accuracy on a control task was associated with yoked activity in the hMT+ and the R aTPJ. We conclude that temporal selective attention is particularly sensitive for revealing information pathways between sensory and core cognitive control networks that, when damaged, can lead to nonspatial attention impairments in right parietal stroke patients. Copyright © 2015 Elsevier Ltd. All rights reserved.
de Vries, Paulien M.; de Jong, Bauke M.; Bohning, Daryl E.; Walker, John A.; George, Mark S.; Leenders, Klaus L.
The left parietal cortex contributes to goal-directed hand movement. In this study, we targeted this region with transcranial magnetic stimulation (TMS) to assess the effects on a wider distributed circuitry related to motor control. Ten healthy subjects underwent 3 Tesla functional magnetic
Pergolizzi, Denise; Chua, Elizabeth F
Neuroimaging data have shown that activity in the lateral posterior parietal cortex (PPC) correlates with item recognition and source recollection, but there is considerable debate about its specific contributions. Performance on both item and source memory tasks were compared between participants who were given bilateral transcranial direct current stimulation (tDCS) over the parietal cortex to those given prefrontal or sham tDCS. The parietal tDCS group, but not the prefrontal group, showed decreased false recognition, and less bias in item and source discrimination tasks compared to sham stimulation. These results are consistent with a causal role of the PPC in item and source memory retrieval, likely based on attentional and decision-making biases. Copyright © 2016 Elsevier Inc. All rights reserved.
Full Text Available Neuronal oscillations in various frequency bands have been reported in numerous studies in both humans and animals. While it is obvious that these oscillations play an important role in cognitive processing, it remains unclear how oscillations in various frequency bands interact. In this study we have investigated phase to power locking in MEG activity of healthy human subjects at rest with their eyes closed. To examine cross-frequency coupling, we have computed coherence between the time course of the power in a given frequency band and the signal itself within every channel. The time-course of the power was calculated using a sliding tapered time window followed by a Fourier transform. Our findings show that high-frequency gamma power (30-70 Hz is phase-locked to alpha oscillations (8-13 Hz in the ongoing MEG signals. The topography of the coupling was similar to the topography of the alpha power and was strongest over occipital areas. Interestingly, gamma activity per se was not evident in the power spectra and only became detectable when studied in relation to the alpha phase. Intracranial data from an epileptic subject confirmed these findings albeit there was slowing in both the alpha and gamma band. A tentative explanation for this phenomenon is that the visual system is inhibited during most of the alpha cycle whereas a burst of gamma activity at a specific alpha phase (e.g. at troughs reflects a window of excitability.
Johnson, Marcia K; Raye, Carol L; Mitchell, Karen J; Touryan, Sharon R; Greene, Erich J; Nolen-Hoeksema, Susan
Motivationally significant agendas guide perception, thought and behaviour, helping one to define a 'self' and to regulate interactions with the environment. To investigate neural correlates of thinking about such agendas, we asked participants to think about their hopes and aspirations (promotion focus) or their duties and obligations (prevention focus) during functional magnetic resonance imaging and compared these self-reflection conditions with a distraction condition in which participants thought about non-self-relevant items. Self-reflection resulted in greater activity than distraction in dorsomedial frontal/anterior cingulate cortex and posterior cingulate cortex/precuneus, consistent with previous findings of activity in these areas during self-relevant thought. For additional medial areas, we report new evidence of a double dissociation of function between medial prefrontal/anterior cingulate cortex, which showed relatively greater activity to thinking about hopes and aspirations, and posterior cingulate cortex/precuneus, which showed relatively greater activity to thinking about duties and obligations. One possibility is that activity in medial prefrontal cortex is associated with instrumental or agentic self-reflection, whereas posterior medial cortex is associated with experiential self-reflection. Another, not necessarily mutually exclusive, possibility is that medial prefrontal cortex is associated with a more inward-directed focus, while posterior cingulate is associated with a more outward-directed, social or contextual focus.
Rizzolatti, Giacomo; Rozzi, Stefano
The mirror mechanism is a basic mechanism that transforms sensory representations of others' actions into motor representations of the same actions in the brain of the observer. The mirror mechanism plays an important role in understanding actions of others. In the present chapter we discuss first the basic organization of the posterior parietal lobe in the monkey, stressing that it is best characterized as a motor scaffold, on the top of which sensory information is organized. We then describe the location of the mirror mechanism in the posterior parietal cortex of the monkey, and its functional role in areas PFG, and anterior, ventral, and lateral intraparietal areas. We will then present evidence that a similar functional organization is present in humans. We will conclude by discussing the role of the mirror mechanism in the recognition of action performed with tools. Copyright © 2018 Elsevier B.V. All rights reserved.
Okazaki, Y.O.; Horschig, J.; Luther, L.M.; Oostenveld, R.; Murakami, I.; Jensen, O.
It has been demonstrated that alpha activity is lateralized when attention is directed to the left or right visual hemifield. We investigated whether real-time neurofeedback training of the alpha lateralization enhances participants' ability to modulate posterior alpha lateralization and causes
Samaha, Jason; Gosseries, Olivia; Postle, Bradley R
Transcranial magnetic stimulation (TMS) of human occipital and posterior parietal cortex can give rise to visual sensations called phosphenes. We used near-threshold TMS with concurrent EEG recordings to measure how oscillatory brain dynamics covary, on single trials, with the perception of phosphenes after occipital and parietal TMS. Prestimulus power and phase, predominantly in the alpha band (8-13 Hz), predicted occipital TMS phosphenes, whereas higher-frequency beta-band (13-20 Hz) power (but not phase) predicted parietal TMS phosphenes. TMS-evoked responses related to phosphene perception were similar across stimulation sites and were characterized by an early (200 ms) posterior negativity and a later (>300 ms) parietal positivity in the time domain and an increase in low-frequency (∼5-7 Hz) power followed by a broadband decrease in alpha/beta power in the time-frequency domain. These correlates of phosphene perception closely resemble known electrophysiological correlates of conscious perception of near-threshold visual stimuli. The regionally differential pattern of prestimulus predictors of phosphene perception suggests that distinct frequencies may reflect cortical excitability in occipital versus posterior parietal cortex, calling into question the broader assumption that the alpha rhythm may serve as a general index of cortical excitability. SIGNIFICANCE STATEMENT Alpha-band oscillations are thought to reflect cortical excitability and are therefore ascribed an important role in gating information transmission across cortex. We probed cortical excitability directly in human occipital and parietal cortex and observed that, whereas alpha-band dynamics indeed reflect excitability of occipital areas, beta-band activity was most predictive of parietal cortex excitability. Differences in the state of cortical excitability predicted perceptual outcomes (phosphenes), which were manifest in both early and late patterns of evoked activity, revealing the time
Holt, Daphne J; Cassidy, Brittany S; Andrews-Hanna, Jessica R; Lee, Su Mei; Coombs, Garth; Goff, Donald C; Gabrieli, John D; Moran, Joseph M
Deficits in social cognition, including impairments in self-awareness, contribute to the overall functional disability associated with schizophrenia. Studies in healthy subjects have shown that social cognitive functions, including self-reflection, rely on the medial prefrontal cortex (mPFC) and posterior cingulate gyrus, and these regions exhibit highly correlated activity during "resting" states. In this study, we tested the hypothesis that patients with schizophrenia show dysfunction of this network during self-reflection and that this abnormal activity is associated with changes in the strength of resting-state correlations between these regions. Activation during self-reflection and control tasks was measured with functional magnetic resonance imaging in 19 patients with schizophrenia and 20 demographically matched control subjects. In addition, the resting-state functional connectivity of midline cortical areas showing abnormal self-reflection-related activation in schizophrenia was measured. Compared with control subjects, the schizophrenia patients demonstrated lower activation of the right ventral mPFC and greater activation of the mid/posterior cingulate gyri bilaterally during self-reflection, relative to a control task. A similar pattern was seen during overall social reflection. In addition, functional connectivity between the portion of the left mid/posterior cingulate gyrus showing abnormally elevated activity during self-reflection in schizophrenia, and the dorsal anterior cingulate gyrus was lower in the schizophrenia patients compared with control subjects. Schizophrenia is associated with an anterior-to-posterior shift in introspection-related activation, as well as changes in functional connectivity, of the midline cortex. These findings provide support for the hypothesis that aberrant midline cortical function contributes to social cognitive impairment in schizophrenia. Copyright © 2011 Society of Biological Psychiatry. Published by Elsevier
Vartanian, Oshin; Beatty, Erin L; Smith, Ingrid; Blackler, Kristen; Lam, Quan; Forbes, Sarah
Contrary to earlier approaches that focused on the contributions of isolated brain regions to the emergence of creativity, there is now growing consensus that creative thought emerges from the interaction of multiple brain regions, often embedded within larger brain networks. Specifically, recent evidence from studies of divergent thinking suggests that kernel ideas emerge in posterior brain regions residing within the semantic system and/or the default mode network (DMN), and that the prefrontal cortex (PFC) regions within the executive control network (ECN) constrain those ideas for generating outputs that meet task demands. However, despite knowing that regions within these networks exhibit interaction, to date the direction of the relationship has not been tested directly. By applying Dynamic Causal Modeling (DCM) to fMRI data collected during a divergent thinking task, we tested the hypothesis that the PFC exerts unidirectional control over the middle temporal gyrus (MTG) and the inferior parietal lobule (IPL), vs. the hypothesis that these two sets of regions exert bidirectional control over each other (in the form of feedback loops). The data were consistent with the former model by demonstrating that the right inferior frontal gyrus (IFG) exerts unidirectional control over MTG and IPL, although the evidence was somewhat stronger in the case of the MTG than the IPL. Our findings highlight potential causal pathways that could underlie the neural bases of divergent thinking. Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.
Cheng, Xiangrong; Zhang, Tailai; Shan, Xinhai; Wang, Jingyuan
The effect of posterior cruciate ligament (PCL) on muscle co-activation (MCO) is not known though MCO has been extensively studied. The purpose of the study was to investigate the effect of PCL creep on MCO and on joint moment around the knee. Twelve males and twelve females volunteered for this study. PCL creep was estimated via tibial posterior displacement which was elicited by a 20kg dumbbell hanged on horizontal shank near patella for 10min. Electromyography activity from both rectus femoris and biceps femoris as well as muscle strength on the right thigh was recorded synchronically during knee isokinetic flexion-extension performance in speed of 60deg/s as well as 120deg/s on a dynamometer before and after PCL creep. A one-way ANOVA with repeated measures was used to evaluate the effect of creep, gender and speed. The results showed that significant tibial posterior displacement was found (p=0.01) in both male and female groups. No significant increase of joint moment was found in flexion as well as in extension phase in both female and male groups. There was a significant effect of speed (p=0.036) on joint moment in extension phase. Co-activation index (CI) decreased significantly (p=0.049) in extension phase with a significant effect of gender (p⩽0.001). It was concluded that creep developed in PCL due to static posterior load on the proximal tibia could significantly elicit the increase of the activation of agonist muscles but with no compensation from the antagonist in flexion as well as in extension phase. The creep significantly elicited the decrease of the antagonist-agonist CI in extension phase. MCO in females was reduced significantly in extension phase. It was suggested that PCL creep might be one of risk factors to the knee injury in sports activity. Copyright © 2014. Published by Elsevier Ltd.
Jonathan R. Whitlock
Full Text Available The posterior parietal cortex (PPC participates in a manifold of cognitive functions, including visual attention, working memory, spatial processing and movement planning. Given the vast interconnectivity of PPC with sensory and motor areas, it is not surprising that neuronal recordings show that PPC often encodes mixtures of spatial information as well as the movements required to reach a goal. Recent work sought to discern the relative strength of spatial versus motor signaling in PPC by recording single unit activity in PPC of freely behaving rats during selective changes in either the spatial layout of the local environment or in the pattern of locomotor behaviors executed during navigational tasks. The results revealed unequivocally a predominant sensitivity of PPC neurons to locomotor action structure, with subsets of cells even encoding upcoming movements more than 1 second in advance. In light of these and other recent findings in the field, I propose that one of the key contributions of PPC to navigation is the synthesis of goal-directed behavioral sequences, and that the rodent PPC may serve as an apt system to investigate cellular mechanisms for spatial motor planning as traditionally studied in humans and monkeys.
Ben-Zvi, Shir; Soroker, Nachum; Levy, Daniel A
We investigated the involvement of the posterior parietal cortex in episodic memory in a lesion-effects study of cued recall following pair-associate learning. Groups of patients who had experienced first-incident stroke, generally in middle cerebral artery territory, and exhibited damage that included lateral posterior parietal regions, were tested within an early post-stroke time window. In three experiments, patients and matched healthy comparison groups executed repeated study and cued recall test blocks of pairs of words (Experiment 1), pairs of object pictures (Experiment 2), or pairs of object pictures and environmental sounds (Experiment 3). Patients' brain CT scans were subjected to quantitative analysis of lesion volumes. Behavioral and lesion data were used to compute correlations between area lesion extent and memory deficits, and to conduct voxel-based lesion-symptom mapping. These analyses implicated lateral ventral parietal cortex, especially the angular gyrus, in cued recall deficits, most pronouncedly in the cross-modal picture-sound pairs task, though significant parietal lesion effects were also found in the unimodal word pairs and picture pairs tasks. In contrast to an earlier study in which comparable parietal lesions did not cause deficits in item recognition, these results indicate that lateral posterior parietal areas make a substantive contribution to demanding forms of recollective retrieval as represented by cued recall, especially for complex associative representations. Copyright © 2015 Elsevier Ltd. All rights reserved.
Salustiano Gomes Lins
Full Text Available Inicialmente é feita breve exposição dos cinco principais tipos de atividade lenta posterior descritas na literatura eletrencefalográfica: variedade lenta do ritmo alfa, ritmo theta posterior, ondas lentas posteriores a 4 hertz, ritmo delta associado ao pequeno mal e ondas Pi. Em seguida o autor expõe seus achados, baseado num material clínico composto por 760 pacientes, colhidos ao acaso, dos dois sexos e com idades variáveis entre 5 e 24 anos. Excetuando a variedade lenta do ritmo alfa, um ou mais dos outros quatro grafo-elementos referidos foram observados em 131 destes pacientes (80 do sexo masculino e 51 do sexo feminino pertencentes aos 3 primeiros grupos etários (5 a 19 anos. Sua predominância no sexo masculino não alcançou nível de significação estatística, mas a maior incidência nos grupos de menor idade foi significativa a 0,01. O ritmo theta posterior associou-se significativamente apenas a distúrbios de conduta com forte agressividade. Dos 131 casos referidos, 10 eram portadores de pequeno mal e destes, 5 apresentavam ritmo delta posterior (3 do sexo masculino e 2 do sexo feminino. Apenas em dois casos foi observado o ritmo lento posterior a 4 hertz, ambos com comemorativos de traumatismo craniano, seguido de distúrbios da conduta e agressividade.The five principal types of posterior slow activity are reviwed: the slow alpha variant rhythm; the posterior theta rhythm; the posterior slow waves at 4 c/s; the delta rhythm associated with petit mal; the so called Pi waves. The results with EEG tracings of 760 patients of both sexes with ages between 5 and 24 years are reviewed. Except for the slow alpha variant, at least one of the four other phenomena as observed in 131 patients (80 males end 51 females. The theta rhythm was observed in 49 cases (29 males and 20 females. This higher frequence among the males is not significant but the higher frequence among the younger and the association with a clinical picture of
Greene, Ciara M; Flannery, Oliver; Soto, David
The two dimensions of emotion, mood valence and arousal, have independent effects on recognition memory. At present, however, it is not clear how those effects are reflected in the human brain. Previous research in this area has generally dealt with memory for emotionally valenced or arousing stimuli, but the manner in which interacting mood and arousal states modulate responses in memory substrates remains poorly understood. We investigated memory for emotionally neutral items while independently manipulating mood valence and arousal state by means of music exposure. Four emotional conditions were created: positive mood/high arousal, positive mood/low arousal, negative mood/high arousal, and negative mood/low arousal. We observed distinct effects of mood valence and arousal in parietal substrates of recognition memory. Positive mood increased activity in ventral posterior parietal cortex (PPC) and orbitofrontal cortex, whereas arousal condition modulated activity in dorsal PPC and the posterior cingulate. An interaction between valence and arousal was observed in left ventral PPC, notably in a parietal area distinct from the those identified for the main effects, with a stronger effect of mood on recognition memory responses here under conditions of relative high versus low arousal. We interpreted the PPC activations in terms of the attention-to-memory hypothesis: Increased arousal may lead to increased top-down control of memory, and hence dorsal PPC activation, whereas positive mood valence may result in increased activity in ventral PPC regions associated with bottom-up attention to memory. These findings indicate that distinct parietal sites mediate the influences of mood, arousal, and their interplay during recognition memory.
Tracey A. Knaus
Full Text Available Autism spectrum disorder (ASD is characterized by deficits in social functioning and language and communication, with restricted interests or stereotyped behaviors. Anatomical differences have been found in the parietal cortex in children with ASD, but parietal subregions and associations between Sylvian fissure (SF and parietal anatomy have not been explored. In this study, SF length and anterior and posterior parietal volumes were measured on MRI in 30 right-handed boys with ASD and 30 right-handed typically developing boys (7–14 years, matched on age and non-verbal IQ. There was leftward SF and anterior parietal asymmetry, and rightward posterior parietal asymmetry, across groups. There were associations between SF and parietal asymmetries, with slight group differences. Typical SF asymmetry was associated with typical anterior and posterior parietal asymmetry, in both groups. In the atypical SF asymmetry group, controls had atypical parietal asymmetry, whereas in ASD there were more equal numbers of individuals with typical as atypical anterior parietal asymmetry. We did not find significant anatomical-behavioral associations. Our findings of more individuals in the ASD group having a dissociation between cortical asymmetries warrants further investigation of these subgroups and emphasizes the importance of investigating anatomical relationships in addition to group differences in individual regions.
Piancino, Maria Grazia; Farina, Dario; Talpone, Francesca; Merlo, Andrea; Bracco, Pietro
The aim of this study was to characterize the kinematics and masseter muscle activation in unilateral posterior crossbite. Eighty-two children (8.6 +/- 1.3 yr of age) with unilateral posterior crossbite and 12 children (8.9 +/- 0.6 yr of age) with normal occlusion were selected for the study. Electromyography (EMG) and kinematics were concurrently recorded during mastication of a soft bolus and a hard bolus. The percentage of reverse cycles in the group of patients was 59.0 +/- 33.1% (soft bolus) and 69.7 +/- 29.7% (hard bolus) when chewing on the crossbite side. When chewing on the non-affected side, the number of reverse cycles was 16.7 +/- 24.5% (soft bolus) and 16.7 +/- 22.3% (hard bolus). The reverse cycles on the crossbite side were narrower with respect to the cycles on the non-affected side. Although both types of cycles in patients resulted in lower EMG activity of the masseter of the crossbite side than of the contralateral masseter, the activity of the non-affected side was larger for reverse than for non-reverse cycles. It was concluded that when chewing on the crossbite side, the masseter activity is reduced on the mastication side (crossbite) and is unaltered (non-reverse cycles) or increased (reverse) on the non-affected side.
Moser, Dana; Baker, Julie M; Sanchez, Carmen E; Rorden, Chris; Fridriksson, Julius
Speech processing requires the temporal parsing of syllable order. Individuals suffering from posterior left hemisphere brain injury often exhibit temporal processing deficits as well as language deficits. Although the right posterior inferior parietal lobe has been implicated in temporal order judgments (TOJs) of visual information, there is limited evidence to support the role of the left inferior parietal lobe (IPL) in processing syllable order. The purpose of this study was to examine whether the left inferior parietal lobe is recruited during temporal order judgments of speech stimuli. Functional magnetic resonance imaging data were collected on 14 normal participants while they completed the following forced-choice tasks: (1) syllable order of multisyllabic pseudowords, (2) syllable identification of single syllables, and (3) gender identification of both multisyllabic and monosyllabic speech stimuli. Results revealed increased neural recruitment in the left inferior parietal lobe when participants made judgments about syllable order compared with both syllable identification and gender identification. These findings suggest that the left inferior parietal lobe plays an important role in processing syllable order and support the hypothesized role of this region as an interface between auditory speech and the articulatory code. Furthermore, a breakdown in this interface may explain some components of the speech deficits observed after posterior damage to the left hemisphere.
Becke, Andreas; Müller, Notger; Vellage, Anne; Schoenfeld, Mircea Ariel; Hopf, Jens-Max
Maintaining information in visual working memory is reliably indexed by the contralateral delay activity (CDA) - a sustained modulation of the event-related potential (ERP) with a topographical maximum over posterior scalp regions contralateral to the memorized input. Based on scalp topography, it is hypothesized that the CDA reflects neural activity in the parietal cortex, but the precise cortical origin of underlying electric activity was never determined. Here we combine ERP recordings with magnetoencephalography based source localization to characterize the cortical current sources generating the CDA. Observers performed a cued delayed match to sample task where either the color or the relative position of colored dots had to be maintained in memory. A detailed source-localization analysis of the magnetic activity in the retention interval revealed that the magnetic analog of the CDA (mCDA) is generated by current sources in the parietal cortex. Importantly, we find that the mCDA also receives contribution from current sources in the ventral extrastriate cortex that display a time-course similar to the parietal sources. On the basis of the magnetic responses, forward modeling of ERP data reveals that the ventral sources have non-optimal projections and that these sources are therefore concealed in the ERP by overlapping fields with parietal projections. The present observations indicate that visual working memory maintenance, as indexed by the CDA, involves the parietal cortical regions as well as the ventral extrastriate regions, which code the sensory representation of the memorized content. Copyright © 2015 Elsevier Inc. All rights reserved.
Werf, J. van der; Buchholz, V.N.; Jensen, O.; Medendorp, W.P.
Neuropsychological and neuroimaging studies have implicated the human posterior parietal cortex (PPC) in sensorimotor integration and saccade planning However, the temporal dynamics of the underlying physiology and its relationship to observations in non-human primates have been difficult to pin
Richardson, Fiona M; Thomas, Michael S C; Filippi, Roberto; Harth, Helen; Price, Cathy J
Using behavioral, structural, and functional imaging techniques, we demonstrate contrasting effects of vocabulary knowledge on temporal and parietal brain structure in 47 healthy volunteers who ranged in age from 7 to 73 years. In the left posterior supramarginal gyrus, vocabulary knowledge was positively correlated with gray matter density in teenagers but not adults. This region was not activated during auditory or visual sentence processing, and activation was unrelated to vocabulary skills. Its gray matter density may reflect the use of an explicit learning strategy that links new words to lexical or conceptual equivalents, as used in formal education and second language acquisition. By contrast, in left posterior temporal regions, gray matter as well as auditory and visual sentence activation correlated with vocabulary knowledge throughout lifespan. We propose that these effects reflect the acquisition of vocabulary through context, when new words are learnt within the context of semantically and syntactically related words.
Schurz, Matthias; Tholen, Matthias G; Perner, Josef; Mars, Rogier B; Sallet, Jerome
In this quantitative review, we specified the anatomical basis of brain activity reported in the Temporo-Parietal Junction (TPJ) in Theory of Mind (ToM) research. Using probabilistic brain atlases, we labeled TPJ peak coordinates reported in the literature. This was carried out for four different atlas modalities: (i) gyral-parcellation, (ii) sulco-gyral parcellation, (iii) cytoarchitectonic parcellation and (iv) connectivity-based parcellation. In addition, our review distinguished between two ToM task types (false belief and social animations) and a nonsocial task (attention reorienting). We estimated the mean probabilities of activation for each atlas label, and found that for all three task types part of TPJ activations fell into the same areas: (i) Angular Gyrus (AG) and Lateral Occpital Cortex (LOC) in terms of a gyral atlas, (ii) AG and Superior Temporal Sulcus (STS) in terms of a sulco-gyral atlas, (iii) areas PGa and PGp in terms of cytoarchitecture and (iv) area TPJp in terms of a connectivity-based parcellation atlas. Beside these commonalities, we also found that individual task types showed preferential activation for particular labels. Main findings for the right hemisphere were preferential activation for false belief tasks in AG/PGa, and in Supramarginal Gyrus (SMG)/PFm for attention reorienting. Social animations showed strongest selective activation in the left hemisphere, specifically in left Middle Temporal Gyrus (MTG). We discuss how our results (i.e., identified atlas structures) can provide a new reference for describing future findings, with the aim to integrate different labels and terminologies used for studying brain activity around the TPJ. Hum Brain Mapp 38:4788-4805, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.
Balestrini, Simona; Francione, Stefano; Mai, Roberto; Castana, Laura; Casaceli, Giuseppe; Marino, Daniela; Provinciali, Leandro; Cardinale, Francesco; Tassi, Laura
The functional complexity of the parietal lobe still represents a challenge for neurophysiological and functional neuroimaging studies. While the somatosensory functions of the anterior parietal cortex are well established, the posterior parietal cortex has a relevant role in processing the sensory information, including visuo-spatial perception, visual attention, visuo-motor transformations and other complex and not completely understood functions. We retrospectively analysed all the clinical manifestations induced by intracerebral bipolar electrical stimulation in 172 patients suffering from drug-resistant focal epilepsy (mean age 25.6, standard deviation 11.6; 44% females and 56% males) with at least one electrode stereotactically implanted in the parietal cortex. A total of 1186 electrical stimulations were included in the analysis, of which 88 were subsequently excluded because of eliciting pathological electric activity or inducing ictal symptomatology. In the dominant parietal lobe, clinical responses were observed for 56 (25%) of the low-frequency stimulations and for 76 (50%) of the high-frequency stimulations. In the non-dominant parietal lobe, 111 (27%) low-frequency and 176 (55%) high-frequency stimulations were associated with a clinical response. Body scheme alteration was the only clinical effect showing a lateralization, as they were evoked only in the non-dominant hemisphere. The occurrence of somatosensory sensations, motor symptoms, dysarthria and multimodal responses were significantly associated with stimulation of the postcentral gyrus (odds ratio: 5.83, P < 0.001; odds ratio: 8.77, P < 0.001; odds ratio: 5.44, P = 0.011; odds ratio: 8.33, P = 0.006; respectively). Stimulation of the intraparietal sulcus was associated with the occurrence of sensory illusions or hallucinations (odds ratio: 8.68, P < 0.001) and eyeball/eyelid movements or sensations (odds ratio: 4.35, P = 0.047). To our knowledge, this is the only currently available complete
Full Text Available The traditional view of the medial temporal lobe (MTL focuses on its role in episodic memory. However, some of the underlying functions of the MTL can be ascertained from its wider role in supporting spatial cognition in concert with parietal and prefrontal regions. The MTL is strongly implicated in the formation of enduring allocentric representations (e.g. O’Keefe (1976; Ekstrom et al. (2003; King et al. (2002. According to our BBB model (Byrne et al. (2007, these representations must interact with head-centered and body-centered representations in posterior parietal cortex via a transformation circuit involving retrosplenial areas. Egocentric sensory representations in parietal areas can then cue the recall of allocentric spatial representations in long-term memory and, conversely, the products of retrieval in MTL can generate mental imagery within a parietal ’window’. Such imagery is necessarily egocentric and forms part of visuospatial working memory, where it can be manipulated for the purpose of planning/imagining the future. Recent fMRI evidence (Lambrey et al. (2012; Zhang et al. (2012 supports the BBB model. To further test the model, we had participants learn the locations of objects in a virtual scene and tested their spatial memory under conditions that impose varying demands on the transformation circuit. We analyzed how brain activity correlated with accuracy in judging the direction of an object 1 from visuospatial working memory (we assume working memory due to the order of tasks and the consistency viewpoint, but long-term memory is also possible, 2 after a rotation of viewpoint, or 3 after a rotation and translation (judgement of relative direction. We found performance-related activity in both tasks requiring viewpoint rotation in the core medial temporal to medial parietal. These results are consistent with the BBB model and shed further light on the mechanisms underlying spatial memory, mental imagery and viewpoint
Zaidel, Adam; DeAngelis, Gregory C; Angelaki, Dora E
Trial-by-trial correlations between neural responses and choices (choice probabilities) are often interpreted to reflect a causal contribution of neurons to task performance. However, choice probabilities may arise from top-down, rather than bottom-up, signals. We isolated distinct sensory and decision contributions to single-unit activity recorded from the dorsal medial superior temporal (MSTd) and ventral intraparietal (VIP) areas of monkeys during perception of self-motion. Superficially, neurons in both areas show similar tuning curves during task performance. However, tuning in MSTd neurons primarily reflects sensory inputs, whereas choice-related signals dominate tuning in VIP neurons. Importantly, the choice-related activity of VIP neurons is not predictable from their stimulus tuning, and these factors are often confounded in choice probability measurements. This finding was confirmed in a subset of neurons for which stimulus tuning was measured during passive fixation. Our findings reveal decoupled stimulus and choice signals in the VIP area, and challenge our understanding of choice signals in the brain.Choice-related signals in neuronal activity may reflect bottom-up sensory processes, top-down decision-related influences, or a combination of the two. Here the authors report that choice-related activity in VIP neurons is not predictable from their stimulus tuning, and that dominant choice signals can bias the standard metric of choice preference (choice probability).
Kesler, Shelli R; Sheau, Kristen; Koovakkattu, Della; Reiss, Allan L
Number sense is believed to be critical for math development. It is putatively an implicitly learned skill and may therefore have limitations in terms of being explicitly trained, particularly in individuals with altered neurodevelopment. A case series study was conducted using an adaptive, computerised programme that focused on number sense and general problem-solving skills. The study was designed to investigate training effects on performance as well as brain function in a group of children with Turner syndrome who are at risk for math difficulties and altered development of math-related brain networks. Standardised measurements of math and math-related cognitive skills as well as functional magnetic resonance imaging (fMRI) were used to assess behavioural and neurobiological outcomes following training. Participants demonstrated significantly increased basic math skills, including number sense, and calculation as well as processing speed, cognitive flexibility and visual-spatial processing skills. With the exception of calculation, increased scores also were clinically significant (i.e., recovered) based on reliable change analysis. Participants additionally demonstrated significantly increased bilateral parietal lobe activation and decreased frontal-striatal and mesial temporal activation following the training programme. These findings show proof of concept for an accessible training approach that may be potentially associated with improved number sense, math and related skills, as well as functional changes in math-related neural systems, even among individuals at risk for altered brain development.
Christophel, Thomas B; Cichy, Radoslaw M; Hebart, Martin N; Haynes, John-Dylan
Active and flexible manipulations of memory contents "in the mind's eye" are believed to occur in a dedicated neural workspace, frequently referred to as visual working memory. Such a neural workspace should have two important properties: The ability to store sensory information across delay periods and the ability to flexibly transform sensory information. Here we used a combination of functional MRI and multivariate decoding to indentify such neural representations. Subjects were required to memorize a complex artificial pattern for an extended delay, then rotate the mental image as instructed by a cue and memorize this transformed pattern. We found that patterns of brain activity already in early visual areas and posterior parietal cortex encode not only the initially remembered image, but also the transformed contents after mental rotation. Our results thus suggest that the flexible and general neural workspace supporting visual working memory can be realized within posterior brain regions. Copyright © 2014 Elsevier Inc. All rights reserved.
Morgan, Helen M; Jackson, Margaret C; van Koningsbruggen, Martijn G; Shapiro, Kimron L; Linden, David E J
In tasks that selectively probe visual or spatial working memory (WM) frontal and posterior cortical areas show a segregation, with dorsal areas preferentially involved in spatial (e.g. location) WM and ventral areas in visual (e.g. object identity) WM. In a previous fMRI study , we showed that right parietal cortex (PC) was more active during WM for orientation, whereas left inferior frontal gyrus (IFG) was more active during colour WM. During WM for colour-orientation conjunctions, activity in these areas was intermediate to the level of activity for the single task preferred and non-preferred information. To examine whether these specialised areas play a critical role in coordinating visual and spatial WM to perform a conjunction task, we used theta burst transcranial magnetic stimulation (TMS) to induce a functional deficit. Compared to sham stimulation, TMS to right PC or left IFG selectively impaired WM for conjunctions but not single features. This is consistent with findings from visual search paradigms, in which frontal and parietal TMS selectively affects search for conjunctions compared to single features, and with combined TMS and functional imaging work suggesting that parietal and frontal regions are functionally coupled in tasks requiring integration of visual and spatial information. Our results thus elucidate mechanisms by which the brain coordinates spatially segregated processing streams and have implications beyond the field of working memory. Copyright © 2013 Elsevier Inc. All rights reserved.
Jae Joon Han
Full Text Available Recent studies have suggested that hyperacusis, an abnormal hypersensitivity to ordinary environmental sounds, may be characterized by certain resting-state cortical oscillatory patterns, even with no sound stimulus. However, previous studies are limited in that most studied subjects with other comorbidities that may have affected cortical activity. In this regard, to assess ongoing cortical oscillatory activity in idiopathic hyperacusis patients with no comorbidities, we compared differences in resting-state cortical oscillatory patterns between five idiopathic hyperacusis subjects and five normal controls. The hyperacusis group demonstrated significantly higher electrical activity in the right auditory-related cortex for the gamma frequency band and left superior parietal lobule (SPL for the delta frequency band versus the control group. The hyperacusis group also showed significantly decreased functional connectivity between the left auditory cortex (AC and left orbitofrontal cortex (OFC, between the left AC and left subgenual anterior cingulate cortex (sgACC for the gamma band, and between the right insula and bilateral dorsal anterior cingulate cortex (dACC and between the left AC and left sgACC for the theta band versus the control group. The higher electrical activity in the SPL may indicate a readiness of "circuit-breaker" activity to shift attention to forthcoming sound stimuli. Also, because of the disrupted salience network, consisting of the dACC and insula, abnormally increased salience to all sound stimuli may emerge, as a consequence of decreased top-down control of the AC by the dACC and dysfunctional emotional weight attached to auditory stimuli by the OFC. Taken together, abnormally enhanced attention and salience to forthcoming sound stimuli may render hyperacusis subjects hyperresponsive to non-noxious auditory stimuli.
Full Text Available Currently the surgical training of parietal bone graft techniques is performed on patients or specimens. Commercially available bone models do not deliver realistic haptic feedback. Thus customized parietal skull surrogates were developed for surgical training purposes. Two human parietal bones were used as reference. Based on the measurement of insertion forces of drilling, milling and saw procedures suitable material compositions for molding cortical and cancellous calvarial layers were found. Artificial skull caps were manufactured and tested. Additionally microtomograpy images of human and artificial parietal bones were performed to analyze outer table and diploe thicknesses. Significant differences between human and artificial skulls were not detected with the mechanical procedures tested. Highly significant differences were found for the diploe thickness values. In conclusion, an artificial bone has been created, mimicking the properties of human parietal bone thus being suitable for tabula externa graft lift training.
Isabel Catarina Duarte
Full Text Available Anterior/posterior long axis specialization is thought to underlie the organization of the hippocampus. However it remains unclear whether antagonistic mechanisms differentially modulate processing of spatial information within the hippocampus. We used fMRI and a virtual reality 3D paradigm to study encoding and retrieval of spatial memory during active visuospatial navigation, requiring positional encoding and retrieval of object landmarks during the path. Both encoding and retrieval elicited BOLD activation of the posterior most portion of hippocampus, while concurrent deactivations (recently shown to reflect decreases in neural responses were found in the most anterior regions. Encoding elicited stronger activity in the posterior right than the left hippocampus. The former structure also showed significantly stronger activity for allocentric vs. egocentric processing during retrieval. The anterior vs. posterior pattern mimics, from a functional point, although at much distinct temporal scales, the previous anatomical findings in London taxi drivers, whereby posterior enlargement was found at the cost of an anterior decrease, and the mirror symmetric findings observed in blind people, in whom the right anterior hippocampus was found to be larger, at the cost of a smaller posterior hippocampus, as compared with sighted people. In sum, we found a functional dichotomy whereby the anterior/posterior hippocampus shows antagonistic processing patterns for spatial encoding and retrieval of 3D spatial information. To our knowledge, this is the first study reporting such a dynamical pattern in a functional study, which suggests that differential modulation of neural responses within the human hippocampus reflects distinct roles in spatial memory processing.
Catherine A. MacLeod
Full Text Available A success story within neuroimaging has been the discovery of distinct neural correlates of episodic retrieval, providing insight into the processes that support memory for past life events. Here we focus on one commonly reported neural correlate, the left parietal old/new effect, a positive going modulation seen in event-related potential (ERP data that is widely considered to index episodic recollection. Substantial evidence links changes in the size of the left parietal effect to changes in remembering, but the precise functional utility of the effect remains unclear. Here, using forced choice recognition of verbal stimuli, we present a novel population level test of the hypothesis that the magnitude of the left parietal effect correlates with memory performance. We recorded ERPs during old/new recognition, source accuracy and Remember/Know/Guess tasks in two large samples of healthy young adults, and successfully replicated existing within participant modulations of the magnitude of the left parietal effect with recollection. Critically, however, both datasets also show that across participants the magnitude of the left parietal effect does not correlate with behavioral measures of memory – including both subjective and objective estimates of recollection. We conclude that in these tasks, and across this healthy young adult population, the generators of the left parietal ERP effect do not index performance as expected. Taken together, these novel findings provide important constraints on the functional interpretation of the left parietal effect, suggesting that between group differences in the magnitude of old/new effects cannot always safely be used to infer differences in recollection.
Hasegawa, Naoya; Kitamura, Hideaki; Murakami, Hiroatsu; Kameyama, Shigeki; Sasagawa, Mutsuo; Egawa, Jun; Endo, Taro; Someya, Toshiyuki
The present study investigated the relationship between neural activity associated with gaze processing and autistic traits in typically developed subjects using magnetoencephalography. Autistic traits in 24 typically developed college students with normal intelligence were assessed using the Autism Spectrum Quotient (AQ). The Minimum Current Estimates method was applied to estimate the cortical sources of magnetic responses to gaze stimuli. These stimuli consisted of apparent motion of the eyes, displaying direct or averted gaze motion. Results revealed gaze-related brain activations in the 150-250 ms time window in the right posterior superior temporal sulcus (pSTS), and in the 150-450 ms time window in medial prefrontal regions. In addition, the mean amplitude in the 150-250 ms time window in the right pSTS region was modulated by gaze direction, and its activity in response to direct gaze stimuli correlated with AQ score. pSTS activation in response to direct gaze is thought to be related to higher-order social processes. Thus, these results suggest that brain activity linking eye contact and social signals is associated with autistic traits in a typical population. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.
Tai, Changfeng; Shen, Bing; Mally, Abhijith D; Zhang, Fan; Zhao, Shouguo; Wang, Jicheng; Roppolo, James R; de Groat, William C
This study determined if activation of somatic afferents in posterior femoral cutaneous nerve (PFCN) could modulate the micturition reflex recorded under isovolumetric conditions in α-chloralose anaesthetized cats. PFCN stimulation inhibited reflex bladder activity and significantly (P acid (AA). The optimal frequency for PFCN stimulation-induced bladder inhibition was between 3 and 10 Hz, and a minimal stimulation intensity of half of the threshold for inducing anal twitching was required. Bilateral pudendal nerve transection eliminated PFCN stimulation-induced anal twitching but did not change the stimulation-induced bladder inhibition, excluding the involvement of pudendal afferent or efferent axons in PFCN afferent inhibition.Mechanical or electrical stimulation on the skin surface in the PFCN dermatome also inhibited bladder activity. Prolonged (2 × 30 min) PFCN stimulation induced a post-stimulation inhibition that persists for at least 2 h. This study revealed a new cutaneous-bladder reflex activated by PFCN afferents. Although the mechanisms and physiological functions of this cutaneous-bladder reflex need to be further studied, our data raise the possibility that stimulation of PFCN afferents might be useful clinically for the treatment of overactive bladder symptoms.
Maria Isabel Lynch
Full Text Available It is quite difficult to diagnose active toxoplasmosis in patients with ocular toxoplasmosis. Active posterior uveitis presumably due to Toxoplasma gondii infection (APUPT is seldom produced during a prime-infection; hence most patients do not show high IgM antibodies. High levels of IgA have been described in active toxoplasmosis. The purpose of this study was to investigate possible association between APUPT and the specific anti-parasite sIgA in tears. The study was carried out as case-control. Tears of 25 clinically confirmed APUPT patients and 50 healthy control subjects were analyzed. All were IgG seropositive. Specific sIgA was determined by ELISA assay using T. gondii RH strain crude extract. Anti-T. gondii sIgA was found in 84% of the cases and in 22% of the control subjects. The intensity of the reaction was higher in APUPT cases (P = 0.007. There was strong association between APUPT patients and lacrimal sIgA (odds-ratio 18.61, P = 0.0001. ELISA test sensitivity was 84% and specificity 78% . Our data suggest that anti-T.gondii secretory IgA found in tears may become an important marker for active ocular toxoplasmosis.
Lynch, Maria Isabel; Cordeiro, Francisco; Ferreira, Silvana; Ximenes, Ricardo; Oréfice, Fernando; Malagueño, Elizabeth
It is quite difficult to diagnose active toxoplasmosis in patients with ocular toxoplasmosis. Active posterior uveitis presumably due to Toxoplasma gondii infection (APUPT) is seldom produced during a prime-infection; hence most patients do not show high IgM antibodies. High levels of IgA have been described in active toxoplasmosis. The purpose of this study was to investigate possible association between APUPT and the specific anti-parasite sIgA in tears. The study was carried out as case-control. Tears of 25 clinically confirmed APUPT patients and 50 healthy control subjects were analyzed. All were IgG seropositive. Specific sIgA was determined by ELISA assay using T. gondii RH strain crude extract. Anti-T. gondii sIgA was found in 84% of the cases and in 22% of the control subjects. The intensity of the reaction was higher in APUPT cases (P = 0.007). There was strong association between APUPT patients and lacrimal sIgA (odds-ratio 18.61, P = 0.0001). ELISA test sensitivity was 84% and specificity 78%. Our data suggest that anti-T.gondii secretory IgA found in tears may become an important marker for active ocular toxoplasmosis.
in abnormal development of the deep layers of the cerebral cortex and production ... focal, unilateral, bilateral or asymmetrical, and have been described in all areas of .... did not recognise food in the mouth, no tongue movement was observed.
Piancino, Maria Grazia; Falla, Deborah; Merlo, Andrea; Vallelonga, Teresa; de Biase, Corrado; Dalessandri, Domenico; Debernardi, Cesare
To describe the effects of therapy on masseter activity and chewing kinematic in patients with unilateral posterior crossbite (UPC). Fifty children (age: mean ± SD: 9.1 ± 2.3 years) with UPC (34 on the right side, 16 on the left side) and twenty children (age: 9.5 ± 2.6 years) with normal occlusion were selected for the study. The mandibular motion and the muscular activity during chewing soft and hard boli were simultaneously recorded, before and after correction with function generating bite, after a mean treatment time of 7.3 ± 2.4 months plus the retention time of 5-6 months. The percentage of reverse cycles and the percent difference between ipsilateral and contralateral peaks of the masseter electromyography envelopes were computed. Before therapy, the percentage of reverse cycles during chewing on the crossbite side was greater in patients than in controls (Preverse chewing patterns. The previous altered muscular activation corresponded to the altered kinematics of reverse chewing cycles that might be considered a useful indicator of the severity of the masticatory function involvement. Copyright © 2016 Elsevier Ltd. All rights reserved.
McGeoch, Paul D; Brang, David; Song, Tao; Lee, Roland R; Huang, Mingxiong; Ramachandran, V S
Damage to the right parietal lobe has long been associated with various disorders of body image. The authors have recently suggested that an unusual behavioural condition in which otherwise rational individuals desire the amputation of a healthy limb might also arise from right parietal dysfunction. Four subjects who desired the amputation of healthy legs (two right, one left and one, at first, bilateral and then left only) were recruited and underwent magnetoencephalography (MEG) scans during tactile stimulation of sites above and below the desired amputation line. Regions of interest (ROIs) in each hemisphere (superior parietal lobule (SPL), inferior parietal lobule, S1, M1, insula, premotor cortex and precuneus) were defined using FreeSurfer software. Analysis of average MEG activity across the 40-140 ms post-stimulation timeframe was carried out using an unpaired t test. This revealed significantly reduced activation only in the right SPL ROI for the subjects' affected legs when compared with both subjects' unaffected legs and that of controls. The right SPL is a cortical area that appears ideally placed to unify disparate sensory inputs to create a coherent sense of having a body. The authors propose that inadequate activation of the right SPL leads to the unnatural situation in which the sufferers can feel the limb in question being touched without it actually incorporating into their body image, with a resulting desire for amputation. The authors introduce the term 'xenomelia' as a more appropriate name than apotemnophilia or body integrity identity disorder, for what appears to be an unrecognised right parietal lobe syndrome.
Moron E, Fanny E; Diaz Marchan, Pedro
The Posterior Reversible Encephalopathy Syndrome (PRES) is a clinical Syndrome composed of cephalea, alteration in vision and convulsions, usually observed in patients with sudden elevation of arterial pressure. The imagenologic evidence shows reversible vasogenic brain edema without stroke. Its location is predominantly posterior; it affects the cortex and the subcortical white matter of the occipital, parietal and temporal lobes. The treatment with antihypertensive drugs and the removing of immunosupressor medication are generally associated with complete neurological recovery; this is reflected also in the images which return to their basal condition. The untreated hypertension, on the other side, can result in a progressive defect of the autoregulation system of the central nervous system with cerebral hemorrhage, irreversible brain stroke, coma and death
Mariana Fregoso Lomas
Full Text Available Spatially restricted epidermal growth factor receptor (EGFR activity plays a central role in patterning the follicular epithelium of the Drosophila ovary. In midoogenesis, localized EGFR activation is achieved by the graded dorsal anterior localization of its ligand, Gurken. Graded EGFR activity determines multiple dorsal anterior fates along the dorsal-ventral axis but cannot explain the sharp posterior limit of this domain. Here, we show that posterior follicle cells express the T-box transcription factors Midline and H15, which render cells unable to adopt a dorsal anterior fate in response to EGFR activation. The posterior expression of Midline and H15 is itself induced in early oogenesis by posteriorly localized EGFR signaling, defining a feedback loop in which early induction of Mid and H15 confers a molecular memory that fundamentally alters the outcome of later EGFR signaling. Spatial regulation of the EGFR pathway thus occurs both through localization of the ligand and through localized regulation of the cellular response.
Full Text Available Summary: The posterior parietal cortex is well known to mediate sensorimotor transformations during the generation of movement plans, but its ability to control prosthetic limbs in 3D environments has not yet been fully demonstrated. With this aim, we trained monkeys to perform reaches to targets located at various depths and directions and tested whether the reach goal position can be extracted from parietal signals. The reach goal location was reliably decoded with accuracy close to optimal (>90%, and this occurred also well before movement onset. These results, together with recent work showing a reliable decoding of hand grip in the same area, suggest that this is a suitable site to decode the entire prehension action, to be considered in the development of brain-computer interfaces. : Filippini et al. show that it is possible to use parietal cortex activity to predict in which direction the arm will move and how far it will reach. This opens up the possibility of neural prostheses that can accurately guide reach and grasp using signals from this part of the brain. Keywords: neuroprosthetics, offline neural decoding, reaching in depth, monkey, V6A, machine learning, visuomotor transformations, hand guidance, prehension, robotics
Dobbins, Ian G; Jaeger, Antonio; Studer, Bettina; Simons, Jon S
The putative role of the lateral parietal lobe in episodic memory has recently become a topic of considerable debate, owing primarily to its consistent activation for studied materials during functional magnetic resonance imaging studies of recognition. Here we examined the performance of patients with parietal lobe lesions using an explicit memory cueing task in which probabilistic cues ("Likely Old" or "Likely New"; 75% validity) preceded the majority of verbal recognition memory probes. Without cues, patients and control participants did not differ in accuracy. However, group differences emerged during the "Likely New" cue condition with controls responding more accurately than parietal patients when these cues were valid (preceding new materials) and trending towards less accuracy when these cues were invalid (preceding old materials). Both effects suggest insufficient integration of external cues into memory judgments on the part of the parietal patients whose cued performance largely resembled performance in the complete absence of cues. Comparison of the parietal patients to a patient group with frontal lobe lesions suggested the pattern was specific to parietal and adjacent area lesions. Overall, the data indicate that parietal lobe patients fail to appropriately incorporate external cues of novelty into recognition attributions. This finding supports a role for the lateral parietal lobe in the adaptive biasing of memory judgments through the integration of external cues and internal memory evidence. We outline the importance of such adaptive biasing through consideration of basic signal detection predictions regarding maximum possible accuracy with and without informative environmental cues. Copyright © 2012 Elsevier Ltd. All rights reserved.
Reznik, Samantha J; Nusslock, Robin; Pornpattananangkul, Narun; Abramson, Lyn Y; Coan, James A; Harmon-Jones, Eddie
Research suggests that midline posterior versus frontal electroencephalographic (EEG) theta activity (PFTA) may reflect a novel neurophysiological index of approach motivation. Elevated PFTA has been associated with approach-related tendencies both at rest and during laboratory tasks designed to enhance approach motivation. PFTA is sensitive to changes in dopamine signaling within the fronto-striatal neural circuit, which is centrally involved in approach motivation, reward processing, and goal-directed behavior. To date, however, no studies have examined PFTA during a laboratory task designed to reduce approach motivation or goal-directed behavior. Considerable animal and human research supports the hypothesis put forth by the learned helplessness theory that exposure to uncontrollable aversive stimuli decreases approach motivation by inducing a state of perceived uncontrollability. Accordingly, the present study examined the effect of perceived uncontrollability (i.e., learned helplessness) on PFTA. EEG data were collected from 74 participants (mean age = 19.21 years; 40 females) exposed to either Controllable (n = 26) or Uncontrollable (n = 25) aversive noise bursts, or a No-Noise Condition (n = 23). In line with prediction, individuals exposed to uncontrollable aversive noise bursts displayed a significant decrease in PFTA, reflecting reduced approach motivation, relative to both individuals exposed to controllable noise bursts or the No-Noise Condition. There was no relationship between perceived uncontrollability and frontal EEG alpha asymmetry, another commonly used neurophysiological index of approach motivation. Results have implications for understanding the neurophysiology of approach motivation and establishing PFTA as a neurophysiological index of approach-related tendencies.
Walden, K; Pornpattananangkul, N; Curlee, A; McAdams, D P; Nusslock, R
Research has recently identified a promising neurophysiological marker of approach motivation involving posterior versus frontal (Pz - Fz) electroencephalographic (EEG) theta activity PFTA; Wacker, Chavanon, & Stemmler (Journal of Personality and Social Psychology 91:171-187, 2006). Preliminary evidence indicated that PFTA is modulated by dopaminergic activity, thought to underlie appetitive tendencies, and that it indexes self-reported behavioral activation system (BAS) sensitivity. To date, research has largely relied on resting indices of PFTA and has yet to examine the relationship between PFTA and specific approach-related affective states generated by emotionally salient laboratory tasks. Accordingly, the present study evaluated PFTA both at rest and during an ecologically valid autobiographical memory task in which participants recalled personal life experiences involving a goal-striving, an anxious apprehension, a low-point (i.e., difficult), and a neutral memory while EEG data were recorded. In line with prediction, elevated PFTA was observed during both goal-striving and anxious apprehension autobiographical memories. PFTA was particularly elevated during anxious apprehension memories coded as being high on approach-related tendencies. Elevated PFTA during anxious apprehension is consistent with a growing literature indicating that anxious apprehension is associated with elevated approach- and reward-related brain function. Lastly, elevated resting PFTA was positively correlated with self-reported trait anger, a negatively valenced emotion characterized by approach-related tendencies. These results have implications for (a) enhancing our understanding of the neurophysiology of approach-related emotions, (b) establishing PFTA as an index of appetitive motivational states, and (c) clarifying our understanding of the neurophysiology and approach-related tendencies associated with both anxious apprehension and anger.
Full Text Available Neurophenomenological studies seek to utilize first-person self-report to elucidate cognitive processes related to physiological data. Grounded theory offers an approach to the qualitative analysis of self-report, whereby theoretical constructs are derived from empirical data. Here we used grounded theory methodology to assess how the first-person experience of meditation relates to neural activity in a core region of the default mode network –the posterior cingulate cortex. We analyzed first-person data consisting of meditators’ accounts of their subjective experience during runs of a real-time fMRI neurofeedback study of meditation, and third-person data consisting of corresponding feedback graphs of posterior cingulate cortex activity during the same runs. We found that for meditators, the subjective experiences of ‘undistracted awareness’ such as ‘concentration’ and ‘observing sensory experience’, and ‘effortless doing’ such as ‘observing sensory experience’, ‘not efforting’, and ‘contentment’, correspond with posterior cingulate cortex deactivation. Further, the subjective experiences of ‘distracted awareness’ such as ‘distraction’ and ‘interpreting’, and ‘controlling’ such as ‘efforting’ and ‘discontentment’, correspond with posterior cingulate cortex activation. Moreover, we derived several novel hypotheses about how specific qualities of cognitive processes during meditation relate to posterior cingulate cortex activity, such as the difference between meditation and ‘trying to meditate’. These findings offer novel insights into the relationship between meditation and self-related thinking and neural activity in the default mode network, driven by the first-person experience.
Cattaneo, Zaira; Lega, Carlotta; Gardelli, Chiara; Merabet, Lotfi B; Cela-Conde, Camilo J; Nadal, Marcos
To explain the biological foundations of art appreciation is to explain one of our species' distinctive traits. Previous neuroimaging and electrophysiological studies have pointed to the prefrontal and the parietal cortex as two critical regions mediating esthetic appreciation of visual art. In this study, we applied transcranial magnetic stimulation (TMS) over the left prefrontal cortex and the right posterior parietal cortex while participants were evaluating whether they liked, and by how much, a particular painting. By depolarizing cell membranes in the targeted regions, TMS transiently interferes with the activity of specific cortical areas, which allows clarifying their role in a given task. Our results show that both regions play a fundamental role in mediating esthetic appreciation. Critically though, the effects of TMS varied depending on the type of art considered (i.e. representational vs. abstract) and on participants' a-priori inclination toward one or the other. Copyright © 2014 Elsevier Inc. All rights reserved.
Full Text Available The neural bases of haptically-guided grasp planning and execution are largely unknown, especially for stimuli having no visual representations. Therefore, we used functional magnetic resonance imaging (fMRI to monitor brain activity during haptic exploration of novel 3D complex objects, subsequent grasp planning, and the execution of the pre-planned grasps. Haptic object exploration, involving extraction of shape, orientation and length of the to-be-grasped targets, was associated with the fronto-parietal, temporo-occipital, and insular cortex activity. Yet, only the anterior divisions of the posterior parietal cortex (PPC of the right hemisphere were significantly more engaged in exploration of complex objects (vs. simple control disks. None of these regions were re-recruited during the planning phase. Even more surprisingly, the left-hemisphere intraparietal, temporal, and occipital areas that were significantly invoked for grasp planning did not show sensitivity to object features. Finally, grasp execution, involving the re-recruitment of the critical right-hemisphere PPC clusters, was also significantly associated with two kinds of bilateral parieto-frontal processes. The first represents transformations of grasp-relevant target features and is linked to the dorso-dorsal (lateral and medial parieto-frontal networks. The second monitors grasp kinematics and belongs to the ventro-dorsal networks. Indeed, signal modulations associated with these distinct functions follow dorso-ventral gradients, with left aIPS showing significant sensitivity to both target features and the characteristics of the required grasp. Thus, our results from the haptic domain are consistent with the notion that the parietal processing for action guidance reflects primarily transformations from object-related to effector-related coding, and these mechanisms are rather independent of sensory input modality.
Macuga, Kristen L; Frey, Scott H
Damage to the superior and/or inferior parietal lobules (SPL, IPL) (Sirigu et al., 1996) or cerebellum (Grealy and Lee, 2011) can selectively disrupt motor imagery, motivating the hypothesis that these regions participate in predictive (i.e., feedforward) control. If so, then the SPL, IPL, and cerebellum should show greater activity as the demands on feedforward control increase from visually-guided execution (closed-loop) to execution without visual feedback (open-loop) to motor imagery. Using fMRI and a Fitts' reciprocal aiming task with tools directed at targets in far space, we found that the SPL and cerebellum exhibited greater activity during closed-loop control. Conversely, open-loop and imagery conditions were associated with increased activity within the IPL and prefrontal areas. These results are consistent with a superior-to-inferior gradient in the representation of feedback-to-feedforward control within the posterior parietal cortex. Additionally, the anterior SPL displayed greater activity when aiming movements were performed with a stick vs. laser pointer. This may suggest that it is involved in the remapping of far into near (reachable) space (Maravita and Iriki, 2004), or in distalization of the end-effector from hand to stick (Arbib et al., 2009). Copyright © 2014 Elsevier Inc. All rights reserved.
May 26, 2015 ... reversible Posterior leukoencephalopathy syndrome [1, 2]. The. PRES is a clinical and radiological entity associating varying degrees, headaches, impaired consciousness, seizures and visual disturbances to neurological and radiological abnormalities of the parietal-occipital white matter . PRES has a ...
Fábio Henrique de Gobbi Porto
Full Text Available Abstract Progressive posterior cortical dysfunction (PPCD is an insidious syndrome characterized by prominent disorders of higher visual processing. It affects both dorsal (occipito-parietal and ventral (occipito-temporal pathways, disturbing visuospatial processing and visual recognition, respectively. We report a case of a 67-year-old woman presenting with progressive impairment of visual functions. Neurologic examination showed agraphia, alexia, hemispatial neglect (left side visual extinction, complete Balint's syndrome and visual agnosia. Magnetic resonance imaging showed circumscribed atrophy involving the bilateral parieto-occipital regions, slightly more predominant to the right . Our aim was to describe a case of this syndrome, to present a video showing the main abnormalities, and to discuss this unusual presentation of dementia. We believe this article can contribute by improving the recognition of PPCD.
Porto, Fábio Henrique de Gobbi; Machado, Gislaine Cristina Lopes; Morillo, Lilian Schafirovits; Brucki, Sonia Maria Dozzi
Progressive posterior cortical dysfunction (PPCD) is an insidious syndrome characterized by prominent disorders of higher visual processing. It affects both dorsal (occipito-parietal) and ventral (occipito-temporal) pathways, disturbing visuospatial processing and visual recognition, respectively. We report a case of a 67-year-old woman presenting with progressive impairment of visual functions. Neurologic examination showed agraphia, alexia, hemispatial neglect (left side visual extinction), complete Balint’s syndrome and visual agnosia. Magnetic resonance imaging showed circumscribed atrophy involving the bilateral parieto-occipital regions, slightly more predominant to the right. Our aim was to describe a case of this syndrome, to present a video showing the main abnormalities, and to discuss this unusual presentation of dementia. We believe this article can contribute by improving the recognition of PPCD. PMID:29213665
Sander M Daselaar
Full Text Available In functional neuroimaging studies, ventral parietal cortex (VPC is recruited by very different cognitive tasks. Explaining the contributions VPC to these tasks has become a topic of intense study and lively debate. Perception studies frequently find VPC activations during tasks involving attention-reorienting, and memory studies frequently find them during tasks involving episodic recollection. According to the Attention to Memory (AtoM model, both phenomena can be explained by the same VPC function: bottom-up attention. Yet, a recent functional MRI (fMRI meta-analysis suggested that attention-reorienting activations are more frequent in anterior VPC, whereas recollection activations are more frequent in posterior VPC. Also, there is evidence that anterior and posterior VPC regions have different functional connectivity patterns. To investigate these issues, we conducted a resting-state functional connectivity analysis using as seeds the center-of-mass of attention-reorienting and recollection activations in the meta-analysis, which were located in the supramarginal gyrus (SMG, around the temporo-parietal junction—TPJ and in the angular gyrus (AG, respectively. The SMG seed showed stronger connectivity with ventrolateral prefrontal cortex (VLPFC and occipito-temporal cortex, whereas the AG seed showed stronger connectivity with the hippocampus and default network regions. To investigate whether these connectivity differences were graded or sharp, VLPFC and hippocampal connectivity was measured in VPC regions traversing through the SMG and AG seeds. The results showed a graded pattern: VLPFC connectivity gradually decreases from SMG to AG, whereas hippocampal connectivity gradually increases from SMG to AG. Importantly, both gradients showed an abrupt break when extended beyond VPC borders. This finding suggests that functional differences between SMG and AG are more subtle than previously thought. These connectivity differences can be
Dhindsa, Kiret; Drobinin, Vladislav; King, John; Hall, Geoffrey B; Burgess, Neil; Becker, Suzanna
The traditional view of the medial temporal lobe (MTL) focuses on its role in episodic memory. However, some of the underlying functions of the MTL can be ascertained from its wider role in supporting spatial cognition in concert with parietal and prefrontal regions. The MTL is strongly implicated in the formation of enduring allocentric representations (e.g., O'Keefe, 1976; King et al., 2002; Ekstrom et al., 2003). According to our BBB model (Byrne et al., 2007), these representations must interact with head-centered and body-centered representations in posterior parietal cortex via a transformation circuit involving retrosplenial areas. Egocentric sensory representations in parietal areas can then cue the recall of allocentric spatial representations in long-term memory and, conversely, the products of retrieval in MTL can generate mental imagery within a parietal "window." Such imagery is necessarily egocentric and forms part of visuospatial working memory, in which it can be manipulated for the purpose of planning/imagining the future. Recent fMRI evidence (Lambrey et al., 2012; Zhang et al., 2012) supports the BBB model. To further test the model, we had participants learn the locations of objects in a virtual scene and tested their spatial memory under conditions that impose varying demands on the transformation circuit. We analyzed how brain activity correlated with accuracy in judging the direction of an object (1) from visuospatial working memory (we assume transient working memory due to the order of tasks and the absence of change in viewpoint, but long-term memory retrieval is also possible), (2) after a rotation of viewpoint, or (3) after a rotation and translation of viewpoint (judgment of relative direction). We found performance-related activity in both tasks requiring viewpoint rotation (ROT and JRD, i.e., conditions 2 and 3) in the core medial temporal to medial parietal circuit identified by the BBB model. These results are consistent with the
Li, Chiang-Shan R.
Abstract The human inferior parietal lobule (IPL) comprised the lateral bank of the intraparietal sulcus, angular gyrus, and supramarginal gyrus, defined on the basis of anatomical landmarks and cytoarchitectural organization of neurons. However, it is not clear as to whether the three areas represent functional subregions within the IPL. For instance, imaging studies frequently identified clusters of activities that cut across areal boundaries. Here, we used resting-state functional magnetic resonance imaging (fMRI) data to examine how individual voxels within the IPL are best clustered according to their connectivity to the whole brain. The results identified a best estimate of seven clusters that are hierarchically arranged as the anterior, middle, and posterior subregions. The anterior, middle, and posterior IPL are each significantly connected to the somatomotor areas, superior/middle/inferior frontal gyri, and regions of the default mode network. This functional segregation is supported by recent cytoarchitechtonics and tractography studies. IPL showed hemispheric differences in connectivity that accord with a predominantly left parietal role in tool use and language processing and a right parietal role in spatial attention and mathematical cognition. The functional clusters may also provide a more parsimonious and perhaps even accurate account of regional activations of the IPL during a variety of cognitive challenges, as reported in earlier fMRI studies. PMID:24308753
Rottschy, C; Caspers, S; Roski, C; Reetz, K; Dogan, I; Schulz, J B; Zilles, K; Laird, A R; Fox, P T; Eickhoff, S B
In a previous meta-analysis across almost 200 neuroimaging experiments, working memory for object location showed significantly stronger convergence on the posterior superior frontal gyrus, whereas working memory for identity showed stronger convergence on the posterior inferior frontal gyrus (dorsal to, but overlapping with Brodmann's area BA 44). As similar locations have been discussed as part of a dorsal frontal-superior parietal reach system and an inferior frontal grasp system, the aim of the present study was to test whether the regions of working-memory related "what" and "where" processing show a similar distinction in parietal connectivity. The regions that were found in the previous meta-analysis were used as seeds for functional connectivity analyses using task-based meta-analytic connectivity modelling and task-independent resting state correlations. While the ventral seed showed significantly stronger connectivity with the bilateral intraparietal sulcus (IPS), the dorsal seed showed stronger connectivity with the bilateral posterior inferior parietal and the medial superior parietal lobule. The observed connections of regions involved in memory for object location and identity thus clearly demonstrate a distinction into separate pathways that resemble the parietal connectivity patterns of the dorsal and ventral premotor cortex in non-human primates and humans. It may hence be speculated that memory for a particular location and reaching towards it as well as object memory and finger positioning for manipulation may rely on shared neural systems. Moreover, the ensuing regions, in turn, featured differential connectivity with the bilateral ventral and dorsal extrastriate cortex, suggesting largely segregated bilateral connectivity pathways from the dorsal visual cortex via the superior and inferior parietal lobules to the dorsal posterior frontal cortex and from the ventral visual cortex via the IPS to the ventral posterior frontal cortex that may
Ursula S Hofstoetter
Full Text Available Epidural electrical stimulation of the lumbar spinal cord is currently regaining momentum as a neuromodulation intervention in spinal cord injury (SCI to modify dysregulated sensorimotor functions and augment residual motor capacity. There is ample evidence that it engages spinal circuits through the electrical stimulation of large-to-medium diameter afferent fibers within lumbar and upper sacral posterior roots. Recent pilot studies suggested that the surface electrode-based method of transcutaneous spinal cord stimulation (SCS may produce similar neuromodulatory effects as caused by epidural SCS. Neurophysiological and computer modeling studies proposed that this noninvasive technique stimulates posterior-root fibers as well, likely activating similar input structures to the spinal cord as epidural stimulation. Here, we add a yet missing piece of evidence substantiating this assumption. We conducted in-depth analyses and direct comparisons of the electromyographic (EMG characteristics of short-latency responses in multiple leg muscles to both stimulation techniques derived from ten individuals with SCI each. Post-activation depression of responses evoked by paired pulses applied either epidurally or transcutaneously confirmed the reflex nature of the responses. The muscle responses to both techniques had the same latencies, EMG peak-to-peak amplitudes, and waveforms, except for smaller responses with shorter onset latencies in the triceps surae muscle group and shorter offsets of the responses in the biceps femoris muscle during epidural stimulation. Responses obtained in three subjects tested with both methods at different time points had near-identical waveforms per muscle group as well as same onset latencies. The present results strongly corroborate the activation of common neural input structures to the lumbar spinal cord-predominantly primary afferent fibers within multiple posterior roots-by both techniques and add to unraveling the
Carlos A. Borzone
Full Text Available A geomorphological and faunistic seasonal study of six estuarine beaches on Paranaguá Bay, Brazil, was abruptly interrupted when the Chilean ship "Vicuña" exploded and sank, spilling 291 tons of bunker fuel oil. The beaches sampled twice before the accident were affected by the oil spill deposition and the posterior clean-up activities. Neither drastic reduction in abundances nor occurrences of oil-covered individuals were registered. Significant variation in both amount of debris and talitrid amphipod densities was directly related to beach clean-up activities. A short (1-3 month manual clean-up of polluted wrack resulted in an increase in talitrid abundances, with the local distribution expansion of one species, Platorchestia monodi, from three to six of the beaches sampled. The active migration and concentration of organisms at sites without wrack during cleaning activities and a massive and continuous recovery of new debris, characteristic of estuarine beaches, may contribute to the findings.Um estudo sazonal da geomorfologia e fauna de seis praias estuarinas na baia de Paranaguá, Brasil, foi interrompido bruscamente pela explosão e posterior afundamento do navio chileno Vicuña, que derramou 291 toneladas de óleo bunker. As praias que foram afetadas pela deposição de óleo e pelas posteriores atividades de limpeza, tinham sido amostradas duas vezes antes do acidente. Nas coletas posteriores ao acidente não foram registradas nem reduções drásticas das abundâncias nem indivíduos impregnados por óleo. As significativas variações tanto da quantidade de detrito quanto nas densidades de anfipodes talitrídeos foram relacionadas às atividades de limpeza. Uma limpeza manual e de curta duração (1 a 3 meses resultou num aumento das abundâncias dos talitrídeos, juntamente com o aumento da distribuição de uma das espécies, Platorchestia monodi, que de três passou a ser encontrada em seis praias amostradas.Os fatores que
Jennifer Lou Langel
Full Text Available The function of the ventral parietal cortex (VPC is subject to much debate. Many studies suggest a lateralization of function in the VPC, with the left hemisphere facilitating verbal working memory and the right subserving stimulus-driven attention. However, many attentional tasks elicit activity in the VPC bilaterally. To elucidate the potential divides across the VPC in function, we assessed the pattern of activity in the VPC bilaterally across two tasks that require different demands, an oddball attentional task with low working memory demands and a working memory task. An anterior region of the VPC was bilaterally active during novel targets in the oddball task and during retrieval in WM, while more posterior regions of the VPC displayed dissociable functions in the left and right hemisphere, with the left being active during the encoding and retrieval of WM, but not during the oddball task and the right showing the reverse pattern. These results suggest that bilateral regions of the anterior VPC subserve non-mnemonic processes, such as stimulus-driven attention during WM retrieval and oddball detection. The left posterior VPC may be important for speech-related processing important for both working memory and perception, while the right hemisphere is more lateralized for attention.
Liliana Rivera Oliva
Full Text Available El encefalocele es una anomalía congénita rara, en la que una porción del encéfalo protruye a través de un orificio craneal (evaginación, generalmente situado en la línea media. Clínicamente se caracteriza por una masa epicraneal, de consistencia blanda, muchas veces acompañada de trastornos psicomotores, convulsiones y trastornos de la visión. Se presenta el caso de un recién nacido con diagnóstico de encefalomeningocele atrésico parietal, intervenido quirúrgicamente y con evolución satisfactoria.The encephalocele is a uncommon congenital anomaly where a portion of encephalon protrudes through a cranial orifice (evagination, generally located in the middle line. Clinically, it is characterized by a soft epicranial mass often accompanied or psychomotor disorders, convulsions and vision disorders. This is the case of a newborn diagnosed with parietal atresic encephalomeningocele operated on with a satisfactory evolution.
Full Text Available Aims: Study on prognostic significance of antenatal ultrasonography and renin angiotensin system activation in predicting disease severity in posterior urethral valves. Materials and Methods: Antenatally diagnosed hydronephrosis patients were included. Postnatally, they were divided into two groups, posterior urethral valve (PUV and non-PUV. The studied parameters were: Gestational age at detection, surgical intervention, ultrasound findings, cord blood and follow up plasma renin activity (PRA values, vesico-ureteric reflux (VUR, renal scars, and glomerular filtration rate (GFR. Results: A total of 25 patients were included, 10 PUV and 15 non-PUV. All infants with PUV underwent primary valve incision. GFR was less than 60 ml/min/1.73 m 2 body surface area in 4 patients at last follow-up. Keyhole sign, oligoamnios, absent bladder cycling, and cortical cysts were not consistent findings on antenatal ultrasound in PUV. Cord blood PRA was significantly higher (P < 0.0001 in PUV compared to non-PUV patients. Gestational age at detection of hydronephrosis, cortical cysts, bladder wall thickness, and amniotic fluid index were not significantly correlated with GFR while PRA could differentiate between poor and better prognosis cases with PUV. Conclusions: Ultrasound was neither uniformly useful in diagnosing PUV antenatally, nor differentiating it from cases with non-PUV hydronephrosis. In congenital hydronephrosis, cord blood PRA was significantly higher in cases with PUV compared to non-PUV cases and fell significantly after valve ablation. Cord blood PRA could distinguish between poor and better prognosis cases with PUV.
Parlatini, Valeria; Radua, Joaquim; Dell'Acqua, Flavio; Leslie, Anoushka; Simmons, Andy; Murphy, Declan G; Catani, Marco; Thiebaut de Schotten, Michel
Experimental data on monkeys and functional studies in humans support the existence of a complex fronto-parietal system activating for cognitive and motor tasks, which may be anatomically supported by the superior longitudinal fasciculus (SLF). Advanced tractography methods have recently allowed the separation of the three branches of the SLF but are not suitable for their functional investigation. In order to gather comprehensive information about the functional organisation of these fronto-parietal connections, we used an innovative method, which combined tractography of the SLF in the largest dataset so far (129 participants) with 14 meta-analyses of functional magnetic resonance imaging (fMRI) studies. We found that frontal and parietal functions can be clustered into a dorsal spatial/motor network associated with the SLF I, and a ventral non-spatial/motor network associated with the SLF III. Further, all the investigated functions activated a middle network mostly associated with the SLF II. Our findings suggest that dorsal and ventral fronto-parietal networks are segregated but also share regions of activation, which may support flexible response properties or conscious processing. In sum, our novel combined approach provided novel findings on the functional organisation of fronto-parietal networks, and may be successfully applied to other brain connections. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.
Oleksiak, Anna; Klink, P. Christiaan; Postma, Albert; van der Ham, Ineke J.M.; Lankheet, Martin J.M.; van Wezel, Richard Jack Anton
While neurons in posterior parietal cortex have been found to signal the presence of a salient stimulus among multiple items in a display, spatial summation within their receptive field in the absence of an attentional bias has never been investigated. This information, however, is indispensable
Full Text Available Efficiently shifting between tasks is a central function of cognitive control. The role of the default network—a constellation of areas with high baseline activity that declines during task performance—in cognitive control remains poorly understood. We hypothesized that task switching demands cognitive control to shift the balance of processing towards the external world, and therefore predicted that switching between the two tasks would require suppression of activity of neurons within the CGp. To test this idea, we recorded the activity of single neurons in posterior cingulate cortex (CGp, a central node in the default network, in monkeys performing two interleaved tasks. As predicted, we found that basal levels of neuronal activity were reduced following a switch from one task to another and gradually returned to pre-switch baseline on subsequent trials. We failed to observe these effects in lateral intraparietal cortex (LIP, part of the dorsal fronto-parietal cortical attention network directly connected to CGp. These findings indicate that suppression of neuronal activity in CGp facilitates cognitive control, and suggest that activity in the default network reflects processes that directly compete with control processes elsewhere in the brain..
Horschig, Jörn M; Oosterheert, Wouter; Oostenveld, Robert; Jensen, Ole
Here we report that the modulation of alpha activity by covert attention can be used as a control signal in an online brain-computer interface, that it is reliable, and that it is robust. Subjects were instructed to orient covert visual attention to the left or right hemifield. We decoded the direction of attention from the magnetoencephalogram by a template matching classifier and provided the classification outcome to the subject in real-time using a novel graphical user interface. Training data for the templates were obtained from a Posner-cueing task conducted just before the BCI task. Eleven subjects participated in four sessions each. Eight of the subjects achieved classification rates significantly above chance level. Subjects were able to significantly increase their performance from the first to the second session. Individual patterns of posterior alpha power remained stable throughout the four sessions and did not change with increased performance. We conclude that posterior alpha power can successfully be used as a control signal in brain-computer interfaces. We also discuss several ideas for further improving the setup and propose future research based on solid hypotheses about behavioral consequences of modulating neuronal oscillations by brain computer interfacing.
Boespflug, E L; McNamara, R K; Eliassen, J C; Schidler, M D; Krikorian, R
To determine the effects of long-chain omega-3 (LCn-3) fatty acids found in fish oil, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), on cortical blood oxygen level-dependent (BOLD) activity during a working memory task in older adults with subjective memory impairment. Randomized, double-blind, placebo-controlled study. Academic medical center. Healthy older adults (62-80 years) with subjective memory impairment, but not meeting criteria for mild cognitive impairment or dementia. Fish oil (EPA+DHA: 2.4 g/d, n=11) or placebo (corn oil, n=10) for 24 weeks. Cortical BOLD response patterns during performance of a sequential letter n-back working memory task were determined at baseline and week 24 by functional magnetic resonance imaging (fMRI). At 24 weeks erythrocyte membrane EPA+DHA composition increased significantly from baseline in participants receiving fish oil (+31%, p ≤ 0.0001) but not placebo (-17%, p=0.06). Multivariate modeling of fMRI data identified a significant interaction among treatment, visit, and memory loading in the right cingulate (BA 23/24), and in the right sensorimotor area (BA 3/4). In the fish oil group, BOLD increases at 24 weeks were observed in the right posterior cingulate and left superior frontal regions during memory loading. A region-of-interest analysis indicated that the baseline to endpoint change in posterior cingulate cortex BOLD activity signal was significantly greater in the fish oil group compared with the placebo group during the 1-back (p=0.0003) and 2-back (p=0.0005) conditions. Among all participants, the change in erythrocyte EPA+DHA during the intervention was associated with performance in the 2-back working memory task (p = 0.01), and with cingulate BOLD signal during the 1-back (p = 0.005) with a trend during the 2-back (p = 0.09). Further, cingulate BOLD activity was related to performance in the 2-back condition. Dietary fish oil supplementation increases red blood cell omega-3 content
Jamie K Fitzgerald
Full Text Available The primate brain is adept at rapidly grouping items and events into functional classes, or categories, in order to recognize the significance of stimuli and guide behavior. Higher cognitive functions have traditionally been considered the domain of frontal areas. However, increasing evidence suggests that parietal cortex is also involved in categorical and associative processes. Previous work showed that the parietal cortex is highly involved in spatial processing, attention and saccadic eye movement planning, and more recent studies have found decision-making signals in LIP. We recently found that a subdivision of parietal cortex, the lateral intraparietal area (LIP, reflects learned categories for multiple types of visual stimuli. Additionally, a comparison of categorization signals in parietal and frontal areas found stronger and earlier categorization signals in parietal cortex, arguing that parietal abstract association or category signals are unlikely to arise via feedback from prefrontal cortex (PFC.
Shoi, K; Fueki, K; Usui, N; Taira, M; Wakabayashi, N
It is well known that shortened dental arch decreases masticatory function. However, its potential to change brain activity during mastication is unknown. The present study investigates the effect of a shortened posterior dental arch with mandibular removable partial dentures (RPDs) on brain activity during gum chewing. Eleven subjects with missing mandibular molars (mean age, 66.1 years) on both sides received experimental RPDs with interchangeable artificial molars in a crossover trial design. Brain activity during gum chewing with RPDs containing (full dental arch) and lacking artificial molars (shortened dental arch) was measured using functional magnetic resonance imaging. Additionally, masticatory function was evaluated for each dental arch type. Food comminuting and mixing ability and the perceived chewing ability were significantly lower in subjects with a shortened dental arch than those with a full dental arch (P chewing with the full dental arch occurred in the middle frontal gyrus, primary sensorimotor cortex extending to the pre-central gyrus, supplementary motor area, putamen, insula and cerebellum. However, middle frontal gyrus activation was not observed during gum chewing with the shortened dental arch. These results suggest that shortened dental arch affects human brain activity in the middle frontal gyrus during gum chewing, and the decreased middle frontal gyrus activation may be associated with decreased masticatory function. © 2014 John Wiley & Sons Ltd.
Meeuwissen, Esther B; Takashima, Atsuko; Fernández, Guillén; Jensen, Ole
It is becoming increasingly clear that demanding cognitive tasks rely on an extended network engaging task-relevant areas and, importantly, disengaging task-irrelevant areas. Given that alpha activity (8-12 Hz) has been shown to reflect the disengagement of task-irrelevant regions in attention and working memory tasks, we here ask if alpha activity plays a related role for long-term memory formation. Subjects were instructed to encode and maintain the order of word sequences while the ongoing brain activity was recorded using magnetoencephalography (MEG). In each trial, three words were presented followed by a 3.4 s rehearsal interval. Considering the good temporal resolution of MEG this allowed us to investigate the word presentation and rehearsal interval separately. The sequences were grouped in trials where word order either could be tested immediately (working memory trials; WM) or later (LTM trials) according to instructions. Subjects were tested on their ability to retrieve the order of the three words. The data revealed that alpha power in parieto-occipital regions was lower during word presentation compared to rehearsal. Our key finding was that parieto-occipital alpha power during the rehearsal period was markedly stronger for successfully than unsuccessfully encoded LTM sequences. This subsequent memory effect demonstrates that high posterior alpha activity creates an optimal brain state for successful LTM formation possibly by actively reducing parieto-occipital activity that might interfere with sequence encoding. Copyright © 2010 Wiley Periodicals, Inc.
Lee, Eun Ja; Yu, Won Jong; Ahn, Kook Jin; Jung, So Lyung; Lee, Yeon Soo; Kim, Ji Chang; Kang, Si Won; Song, Chang Joon; Song, Soon-Young; Koo, Ja Hong; Kim, Man Deuk
To review reversible posterior leukoencephalopathy syndrome. We reviewed 22 patients (M:F=3:19; age, 17-46 years) with the characteristic clinical and imaging features of reversible posterior leukoencephalopathy syndrome. All underwent brain MRI, and in three cases both CT and MRI were performed. In one, MRA was obtained, and in eleven, follow-up MR images were obtained. We evaluated the causes of this syndrome, its clinical manifestations, and MR findings including the locations of lesions, the presence or absence of contrast enhancement, and the changes seen at follow-up MRI. Of the 22 patients, 13 had eclampsia (six during pregnancy and seven during puerperium). Four were receiving immunosuppressive therapy (three, cyclosporine ; one, FK 506). Four suffered renal failure and one had complicated migraine. The clinical manifestations included headache (n=12), visual disturbance (n=13), seizure (n=15), focal neurologic sign (n=3), and altered mental status (n=2). Fifteen patients had hypertension and the others normotension. MRI revealed that lesions were bilateral (n=20) or unilateral (n=2). In all patients the lesion was found in the cortical and subcortical areas of the parieto-occipital lobes ; other locations were the basal ganglia (n=9), posterior temporal lobe (n=8), frontal lobe (n=5), cerebellum (n=5), pons (n=2), and thalamus (n=1). All lesions were of high signal intensity on T2-weighted images, and of iso to low intensity on T1-weighted images. One was combined with acute hematoma in the left basal ganglia. In eight of 11 patients who underwent postcontrast T1-weighted MRI, there was no definite enhancement ; in one, enhancement was mild, and in tow, patchy. CT studies showed low attenuation, and MRA revealed mild vasospasm. The symptoms of all patients improved. Follow-up MRI in nine of 11 patients depicted complete resolution of the lesions ; in two, small infarctions remained but the extent of the lesions had decreased. Reversible posterior
Lee, Eun Ja; Yu, Won Jong; Ahn, Kook Jin; Jung, So Lyung; Lee, Yeon Soo; Kim, Ji Chang; Kang, Si Won [The Catholic Univ. of Korea, Taejon (Korea, Republic of); Song, Chang Joon [Chungnam National Univ. School of Medicine, Cheonju (Korea, Republic of); Song, Soon-Young; Koo, Ja Hong [Kwandong Univ. College of Medicine, Myungji Hospital, Seoul (Korea, Republic of); Kim, Man Deuk [College of Medicine Pochon CHA Univ., Seoul (Korea, Republic of)
To review reversible posterior leukoencephalopathy syndrome. We reviewed 22 patients (M:F=3:19; age, 17-46 years) with the characteristic clinical and imaging features of reversible posterior leukoencephalopathy syndrome. All underwent brain MRI, and in three cases both CT and MRI were performed. In one, MRA was obtained, and in eleven, follow-up MR images were obtained. We evaluated the causes of this syndrome, its clinical manifestations, and MR findings including the locations of lesions, the presence or absence of contrast enhancement, and the changes seen at follow-up MRI. Of the 22 patients, 13 had eclampsia (six during pregnancy and seven during puerperium). Four were receiving immunosuppressive therapy (three, cyclosporine ; one, FK 506). Four suffered renal failure and one had complicated migraine. The clinical manifestations included headache (n=12), visual disturbance (n=13), seizure (n=15), focal neurologic sign (n=3), and altered mental status (n=2). Fifteen patients had hypertension and the others normotension. MRI revealed that lesions were bilateral (n=20) or unilateral (n=2). In all patients the lesion was found in the cortical and subcortical areas of the parieto-occipital lobes ; other locations were the basal ganglia (n=9), posterior temporal lobe (n=8), frontal lobe (n=5), cerebellum (n=5), pons (n=2), and thalamus (n=1). All lesions were of high signal intensity on T2-weighted images, and of iso to low intensity on T1-weighted images. One was combined with acute hematoma in the left basal ganglia. In eight of 11 patients who underwent postcontrast T1-weighted MRI, there was no definite enhancement ; in one, enhancement was mild, and in tow, patchy. CT studies showed low attenuation, and MRA revealed mild vasospasm. The symptoms of all patients improved. Follow-up MRI in nine of 11 patients depicted complete resolution of the lesions ; in two, small infarctions remained but the extent of the lesions had decreased. Reversible posterior
Kevin A. Bockerstett
Full Text Available Background & Aims: Atrophic gastritis caused by chronic inflammation in the gastric mucosa leads to the loss of gastric glandular cells, including acid-secreting parietal cells. Parietal cell atrophy in a setting of chronic inflammation induces spasmolytic polypeptide expressing metaplasia, a critical step in gastric carcinogenesis. However, the mechanisms by which inflammation causes parietal cell atrophy and spasmolytic polypeptide expressing metaplasia are not well defined. We investigated the role of interleukin-17A (IL-17A in causing parietal cell atrophy. Methods: A mouse model of autoimmune atrophic gastritis was used to examine IL-17A production during early and late stages of disease. Organoids derived from corpus glands were used to determine the direct effects of IL-17A on gastric epithelial cells. Immunofluorescent staining was used to examine IL-17A receptors and the direct effect of signaling on parietal cells. Mice were infected with an IL-17A-producing adenovirus to determine the effects of IL-17A on parietal cells in vivo. Finally, IL-17A neutralizing antibodies were administered to mice with active atrophic gastritis to evaluate the effects on parietal cell atrophy and metaplasia. Results: Increased IL-17A correlated with disease severity in mice with chronic atrophic gastritis. IL-17A caused caspase-dependent gastric organoid degeneration, which could not be rescued with a necroptosis inhibitor. Parietal cells expressed IL-17A receptors and IL-17A treatment induced apoptosis in parietal cells. Overexpressing IL-17A in vivo induced caspase-3 activation and terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate nick-end labeling staining in parietal cells. Finally, IL-17A neutralizing antibody decreased parietal cell atrophy and metaplasia in mice with chronic atrophic gastritis. Conclusions: These data identify IL-17A as a cytokine that promotes parietal cell apoptosis during atrophic gastritis, a
Mahaki, M; Mi'mar, R; Mahaki, B
Anterior cruciate ligament (ACL) injury continues to be an important medical issue for athletes participating in sports. Vertical and posterior ground reaction forces have received considerable attention for their potential influence on ACL injuries. The purpose of this study was to examine the relationship between electromyographic activity of lower extremity muscles and the peak vertical and posterior ground reaction forces during single leg drop landing. Thirteen physical education male students participated in this correlation study. Electromyographic activities of gluteus medius, biceps femoris, medial gastrocnemius, soleus as well as anterior tibialis muscles along with ground reaction forces were measured. Participants performed single-leg landing from a 0.3 m height on to a force platform. Landing was divided into two phases: 100 ms preceding ground contact and 100 ms proceeding ground contact. Pearson correlation test was used to determine the relationships between these muscles activity and peak vertical and posterior ground reaction forces. The results of the study indicated that the activity of soleus and tibialis anterior in pre-landing phase were positively correlated with peak vertical ground reaction force ([P≤0.04], [P≤0.008], respectively). However, no significant correlation was found between the activities of other muscles in pre-landing phase and peak vertical as well as peak posterior ground reaction forces. Also, no significant correlation was found between the activities of muscles in post-landing phase and peak vertical as well as peak posterior ground reaction forces. Soleus loading shifts the proximal tibia posterior at the knee joint and tibialis anterior prevent hyperporonation of the ankle, a mechanisms of ACL injury. Hence, neuromuscular training promoting preparatory muscle activity in these muscles may reduce the incidence of ACL injuries.
Rohde, S.; Weidauer, S.; Lanfermann, H.; Zanella, F.
The alien hand syndrome (AHS) is involuntary uncontrolled movement of an arm with a sense of estrangement from the limb itself. AHS was initially used to describe interhemispheric disconnection phenomena in patients with lesions in the anterior corpus callosum, but it has been found in patients with posterior cerebral lesions without involvement of the corpus callosum, for example parietal infarcts or corticobasal degeneration. The posterior alien hand syndrome is less frequent and presents with nonpurposive behaviour like lifting the arm or writhing fingers. We report an 80-year-old woman with a posterior AHS of the dominant right hand. MRI showed atrophy of the pre- and postcentral gyri without involvement of the corpus callosum. We discuss the aetiology of the posterior AHS and the differences from the anterior varieties. (orig.)
Jan Christopher Cwik
Full Text Available Functional imaging studies of patients with Posttraumatic Stress Disorder showed wide-spread activation of mid-line cortical areas during symptom provocation i.e., exposure to trauma-related cues. The present study aimed at investigating neural activation during exposure to trauma-related pictures in patients with Acute Stress Disorder (ASD shortly after the traumatic event. Nineteen ASD patients and 19 healthy control participants were presented with individualized pictures of the traumatic event and emotionally neutral control pictures during the acquisition of whole-brain data with a 3-T fMRI scanner. Compared to the control group and to control pictures, ASD patients showed significant activation in mid-line cortical areas in response to trauma-related pictures including precuneus, cuneus, postcentral gyrus and pre-supplementary motor area. The results suggest that the trauma-related pictures evoke emotionally salient self-referential processing in ASD patients.
Bariety, Jean; Mandet, Chantal; Hill, Gary S; Bruneval, Patrick
Although parietal podocytes along the Bowman's capsule have been described by electron microscopy in the normal human kidney, their molecular composition remains unknown. Ten human normal kidneys that were removed for cancer were assessed for the presence and the extent of parietal podocytes along the Bowman's capsule. The expression of podocyte-specific proteins (podocalyxin, glomerular epithelial protein-1, podocin, nephrin, synaptopodin, and alpha-actinin-4), podocyte synthesized proteins (vascular endothelial growth factor and novH), transcription factors (WT1 and PAX2), cyclin-dependent kinase inhibitor p57, and intermediate filaments (cytokeratins and vimentin) was tested. In addition, six normal fetal kidneys were studied to track the ontogeny of parietal podocytes. The podocyte protein labeling detected parietal podocytes in all of the kidneys, was found in 76.6% on average of Bowman's capsule sections, and was prominent at the vascular pole. WT1 and p57 were expressed in some parietal cells, whereas PAX2 was present in all or most of them, so some parietal cells coexpressed WT1 and PAX2. Furthermore, parietal podocytes coexpressed WT1 and podocyte proteins. Cytokeratin-positive cells covered a variable part of the capsule and did not express podocyte proteins. Tuft-capsular podocyte bridges were present in 15.5 +/- 3.7% of the glomerular sections. Parietal podocytes often covered the juxtaglomerular arterioles and were present within the extraglomerular mesangium. Parietal podocytes were present in fetal kidneys. Parietal podocytes that express the same epitopes as visceral podocytes do exist along Bowman's capsule in the normal adult kidney. They are a constitutive cell type of the Bowman's capsule. Therefore, their role in physiology and pathology should be investigated.
Li, Jianlin; Du, Dunren; Gao, Wei; Sun, Xichun; Xie, Haizhu; Zhang, Gang; Li, Jian; Li, Honglun; Li, Kefeng
Aphasia is one of the most disabling cognitive deficits affecting >2 million people in the USA. The neuroimaging characteristics of chronic aphasic patients (>6 months post onset) remain largely unknown. The objective of this study was to investigate the regional signal changes of spontaneous neuronal activity of brain and the inter-regional connectivity in chronic aphasia. Resting-state blood oxygenation level-dependent functional magnetic resonance imaging (fMRI) was used to obtain fMRI data from 17 chronic aphasic patients and 20 healthy control subjects in a Siemens Verio 3.0T MR Scanner. The amplitude of low-frequency fluctuation (ALFF) was determined, which directly reflects the regional neuronal activity. The functional connectivity (FC) of fMRI was assessed using a seed voxel linear correlation approach. The severity of aphasia was evaluated by aphasia quotient (AQ) scores obtained from Western Aphasia Battery test. Compared with normal subjects, aphasic patients showed decreased ALFF values in the regions of left posterior middle temporal gyrus (PMTG), left medial prefrontal gyrus, and right cerebellum. The ALFF values in left PMTG showed strong positive correlation with the AQ score (coefficient r =0.79, P temporal gyrus (BA20), fusiform gyrus (BA37), and inferior frontal gyrus (BA47\\45\\44). Left PMTG might play an important role in language dysfunction of chronic aphasia, and ALFF value might be a promising indicator to evaluate the severity of aphasia.
Marije van Beilen
Full Text Available The etiology of medically unexplained symptoms such as conversion disorder is poorly understood. This is partly because the interpretation of neuroimaging results in conversion paresis has been complicated by the use of different control groups, tasks and statistical comparisons. The present study includes these different aspects in a single data set. In our study we included both normal controls and feigners to control for conversion paresis. We studied both movement execution and imagery, and we contrasted both within-group and between-group activation. Moreover, to reveal hemisphere-specific effects that have not been reported before, we performed these analyses using both flipped and unflipped data. This approach resulted in the identification of abnormal parietal activation which was specific for conversion paresis patients. Patients also showed reduced activity in the prefrontal cortex, supramarginal gyrus and precuneus, including hemisphere-specific activation that is lateralized in the same hemisphere, regardless of right- or left-sided paresis. We propose that these regions are candidates for an interface between psychological mechanisms and disturbed higher-order motor control. Our study presents an integrative neurophysiological view of the mechanisms that contribute to the etiology of this puzzling psychological disorder, which can be further investigated with other types of conversion symptoms.
Marangon, Mattia; Kubiak, Agnieszka; Króliczak, Gregory
The neural bases of haptically-guided grasp planning and execution are largely unknown, especially for stimuli having no visual representations. Therefore, we used functional magnetic resonance imaging (fMRI) to monitor brain activity during haptic exploration of novel 3D complex objects, subsequent grasp planning, and the execution of the pre-planned grasps. Haptic object exploration, involving extraction of shape, orientation, and length of the to-be-grasped targets, was associated with the fronto-parietal, temporo-occipital, and insular cortex activity. Yet, only the anterior divisions of the posterior parietal cortex (PPC) of the right hemisphere were significantly more engaged in exploration of complex objects (vs. simple control disks). None of these regions were re-recruited during the planning phase. Even more surprisingly, the left-hemisphere intraparietal, temporal, and occipital areas that were significantly invoked for grasp planning did not show sensitivity to object features. Finally, grasp execution, involving the re-recruitment of the critical right-hemisphere PPC clusters, was also significantly associated with two kinds of bilateral parieto-frontal processes. The first represents transformations of grasp-relevant target features and is linked to the dorso-dorsal (lateral and medial) parieto-frontal networks. The second monitors grasp kinematics and belongs to the ventro-dorsal networks. Indeed, signal modulations associated with these distinct functions follow dorso-ventral gradients, with left aIPS showing significant sensitivity to both target features and the characteristics of the required grasp. Thus, our results from the haptic domain are consistent with the notion that the parietal processing for action guidance reflects primarily transformations from object-related to effector-related coding, and these mechanisms are rather independent of sensory input modality.
Arnaldo, Francis B; Villar, Van Anthony M; Konkalmatt, Prasad R; Owens, Shaun A; Asico, Laureano D; Jones, John E; Yang, Jian; Lovett, Donald L; Armando, Ines; Jose, Pedro A; Concepcion, Gisela P
Dopamine-mediated regulation of Na(+)-K(+)-ATPase activity in the posterior gills of some crustaceans has been reported to be involved in osmoregulation. The dopamine receptors of invertebrates are classified into three groups based on their structure and pharmacology: D1- and D2-like receptors and a distinct invertebrate receptor subtype (INDR). We tested the hypothesis that a D1-like receptor is expressed in the blue crab Callinectes sapidus and regulates Na(+)-K(+)-ATPase activity. RT-PCR, using degenerate primers, showed the presence of D1βR mRNA in the posterior gill. The blue crab posterior gills showed positive immunostaining for a dopamine D5 receptor (D5R or D1βR) antibody in the basolateral membrane and cytoplasm. Confocal microscopy showed colocalization of Na(+)-K(+)-ATPase and D1βR in the basolateral membrane. To determine the effect of D1-like receptor stimulation on Na(+)-K(+)-ATPase activity, intact crabs acclimated to low salinity for 6 days were given an intracardiac infusion of the D1-like receptor agonist fenoldopam, with or without the D1-like receptor antagonist SCH23390. Fenoldopam increased cAMP production twofold and decreased Na(+)-K(+)-ATPase activity by 50% in the posterior gills. This effect was blocked by coinfusion with SCH23390, which had no effect on Na(+)-K(+)-ATPase activity by itself. Fenoldopam minimally decreased D1βR protein expression (10%) but did not affect Na(+)-K(+)-ATPase α-subunit protein expression. This study shows the presence of functional D1βR in the posterior gills of euryhaline crabs chronically exposed to low salinity and highlights the evolutionarily conserved function of the dopamine receptors on sodium homeostasis. Copyright © 2014 the American Physiological Society.
Full Text Available Recent works evince the critical role of visual short-term memory (STM binding deficits as a clinical and preclinical marker of Alzheimer’s disease (AD. These studies suggest a potential role of posterior brain regions in both the neurocognitive deficits of Alzheimer’s patients and STM binding in general. Thereupon, we surmised that stimulation of the posterior parietal cortex (PPC might be a successful approach to tackle working memory deficits in this condition, especially at early stages. To date, no causal evidence exists of the role of the parietal cortex in STM binding. A unique approach to assess this issue is afforded by single-subject direct intracranial electrical stimulation of specific brain regions during a relevant cognitive task. Electrical stimulation has been used both for clinical purposes and to causally probe brain mechanisms. Previous evidence of electrical currents spreading through white matter along well defined functional circuits indicates that visual working memory mechanisms are subserved by a specific widely distributed network. Here, we stimulated the parietal cortex of a subject with intracranial electrodes as he performed the visual STM task. We compared the ensuing results to those from a non-stimulated condition and to the performance of a matched control group. In brief, direct stimulation of the parietal cortex induced a selective improvement in STM. These results, together with previous studies, provide very preliminary but promising ground to examine behavioral changes upon parietal stimulation in AD. We discuss our results regarding: (a the usefulness of the task to target prodromal stages of AD; (b the role of a posterior network in STM binding and in AD; and (c the potential opportunity to improve STM binding through brain stimulation.
Casey, S.O.; McKinney, A.; Teksam, M.; Liu, H.; Truwit, C.L.
A 13-year-old girl with a renal transplant presented with hypertension and seizures. CT and MRI demonstrated typical bilateral parietal, occipital and posterior frontal cortical and subcortical edema, thought to represent posterior reversible encephalopathy syndrome. The cause was presumed to be hypertension. Antihypertensive therapy was started, lowering of the blood pressure in the range of 110-120 mmHg systolic. However, stable xenon (Xe) CT perfusion imaging revealed ischemia within the left parietal occipital region. The antihypertensive was adjusted which increased both the systolic and diastolic blood pressure by 31 mm Hg. The patient was re-imaged with Xe CT and was found to have resolution of the ischemic changes within the left parietal occipital region. In this report, we present a case in which stable Xe CT was used to monitor the degree of cerebral perfusion and guide titration of antihypertensive therapy. Such brain perfusion monitoring may have helped to prevent infarction of our patient. (orig.)
Wu, Xiu-Jie; Xing, Song; Trinkaus, Erik
We report here a neurocranial abnormality previously undescribed in Pleistocene human fossils, an enlarged parietal foramen (EPF) in the early Late Pleistocene Xujiayao 11 parietal bones from the Xujiayao (Houjiayao) site, northern China. Xujiayao 11 is a pair of partial posteromedial parietal bones from an adult. It exhibits thick cranial vault bones, arachnoid granulations, a deviated posterior sagittal suture, and a unilateral (right) parietal lacuna with a posteriorly-directed and enlarged endocranial vascular sulcus. Differential diagnosis indicates that the perforation is a congenital defect, an enlarged parietal foramen, commonly associated with cerebral venous and cranial vault anomalies. It was not lethal given the individual's age-at-death, but it may have been associated with secondary neurological deficiencies. The fossil constitutes the oldest evidence in human evolution of this very rare condition (a single enlarged parietal foramen). In combination with developmental and degenerative abnormalities in other Pleistocene human remains, it suggests demographic and survival patterns among Pleistocene Homo that led to an elevated frequency of conditions unknown or rare among recent humans.
Full Text Available We report here a neurocranial abnormality previously undescribed in Pleistocene human fossils, an enlarged parietal foramen (EPF in the early Late Pleistocene Xujiayao 11 parietal bones from the Xujiayao (Houjiayao site, northern China. Xujiayao 11 is a pair of partial posteromedial parietal bones from an adult. It exhibits thick cranial vault bones, arachnoid granulations, a deviated posterior sagittal suture, and a unilateral (right parietal lacuna with a posteriorly-directed and enlarged endocranial vascular sulcus. Differential diagnosis indicates that the perforation is a congenital defect, an enlarged parietal foramen, commonly associated with cerebral venous and cranial vault anomalies. It was not lethal given the individual's age-at-death, but it may have been associated with secondary neurological deficiencies. The fossil constitutes the oldest evidence in human evolution of this very rare condition (a single enlarged parietal foramen. In combination with developmental and degenerative abnormalities in other Pleistocene human remains, it suggests demographic and survival patterns among Pleistocene Homo that led to an elevated frequency of conditions unknown or rare among recent humans.
Full Text Available The human primary motor cortex has dual representation of the digits, namely, area 4 anterior (MI-4a and area 4 posterior (MI-4p. We have previously demonstrated that activation of these two functional subunits can be identified independently by functional magnetic resonance imaging (fMRI using independent component-cross correlation-sequential epoch (ICS analysis. Subsequent studies in patients with hemiparesis due to subcortical lesions and monoparesis due to peripheral nerve injury demonstrated that MI-4p represents the initiation area of activation, whereas MI-4a is the secondarily activated motor cortex requiring a “long-loop” feedback input from secondary motor systems, likely the cerebellum. A dynamic model of hand motion based on the limit cycle oscillator predicts that the specific pattern of entrainment of neural firing may occur by applying appropriate periodic stimuli. Under normal conditions, such entrainment introduces a single phase-cluster. Under pathological conditions where entrainment stimuli have insufficient strength, the phase cluster splits into two clusters. Observable physiological phenomena of this shift from single cluster to two clusters are: doubling of firing rate of output neurons; or decay in group firing density of the system due to dampening of odd harmonics components. While the former is not testable in humans, the latter can be tested by appropriately designed fMRI experiments, the quantitative index of which is believed to reflect group behavior of neurons functionally localized, e.g., firing density in the dynamic theory. Accordingly, we performed dynamic analysis of MI-4p activation in normal volunteers and paretic patients. The results clearly indicated that MI-4p exhibits a transition from a single to a two phase-cluster state which coincided with loss of MI-4a activation. The study demonstrated that motor dysfunction (hemiparesis in patients with a subcortical infarct is not simply due to afferent
Schaal, Nora K; Javadi, Amir-Homayoun; Halpern, Andrea R; Pollok, Bettina; Banissy, Michael J
Functional brain imaging studies have highlighted the significance of right-lateralized temporal, frontal and parietal brain areas for memory for melodies. The present study investigated the involvement of bilateral posterior parietal cortices (PPCs) for the recognition memory of melodies using transcranial direct current stimulation (tDCS). Participants performed a recognition task before and after tDCS. The task included an encoding phase (12 melodies), a retention period, as well as a recognition phase (24 melodies). Experiment 1 revealed that anodal tDCS over the right PPC led to a deterioration of overall memory performance compared with sham. Experiment 2 confirmed the results of Experiment 1 and further showed that anodal tDCS over the left PPC did not show a modulatory effect on memory task performance, indicating a right lateralization for musical memory. Furthermore, both experiments revealed that the decline in memory for melodies can be traced back to an interference of anodal stimulation on the recollection process (remember judgements) rather than to familiarity judgements. Taken together, this study revealed a causal involvement of the right PPC for memory for melodies and demonstrated a key role for this brain region in the recollection process of the memory task. © 2015 The Authors. European Journal of Neuroscience published by Federation of European Neuroscience Societies and John Wiley & Sons Ltd.
Castellano, Marta; Plöchl, Michael; Vicente, Raul; Pipa, Gordon
The ability to integrate visual features into a global coherent percept that can be further categorized and manipulated are fundamental abilities of the neural system. While the processing of visual information involves activation of early visual cortices, the recruitment of parietal and frontal cortices has been shown to be crucial for perceptual processes. Yet is it not clear how both cortical and long-range oscillatory activity leads to the integration of visual features into a coherent percept. Here, we will investigate perceptual grouping through the analysis of a contour categorization task, where the local elements that form contour must be linked into a coherent structure, which is then further processed and manipulated to perform the categorization task. The contour formation in our visual stimulus is a dynamic process where, for the first time, visual perception of contours is disentangled from the onset of visual stimulation or from motor preparation, cognitive processes that until now have been behaviorally attached to perceptual processes. Our main finding is that, while local and long-range synchronization at several frequencies seem to be an ongoing phenomena, categorization of a contour could only be predicted through local oscillatory activity within parietal/frontal sources, which in turn, would synchronize at gamma (>30 Hz) frequency. Simultaneously, fronto-parietal beta (13-30 Hz) phase locking forms a network spanning across neural sources that are not category specific. Both long range networks, i.e., the gamma network that is category specific, and the beta network that is not category specific, are functionally distinct but spatially overlapping. Altogether, we show that a critical mechanism underlying contour categorization involves oscillatory activity within parietal/frontal cortices, as well as its synchronization across distal cortical sites.
Full Text Available The present study investigated the neural mechanisms that contribute to the detection of visual feature changes between stimulus displays by means of event-related lateralizations of the electroencephalogram (EEG. Participants were instructed to respond to a luminance change in either of two lateralized stimuli that could randomly occur alone or together with an irrelevant orientation change of the same or contralateral stimulus. Task performance based on response times and accuracy was decreased compared to the remaining stimulus conditions when relevant and irrelevant feature changes were presented contralateral to each other (lateral distractor condition. The sensory response to the feature changes was reflected in a posterior contralateral positivity at around 100ms after change presentation and a posterior contralateral negativity in the N1 time window (N1pc. N2pc reflected a subsequent attentional bias in favor of the relevant luminance change. The continuation of the sustained posterior contralateral negativity (SPCN following N2pc covaried with response times within feature change conditions and revealed a posterior topography comparable to the earlier components associated with sensory and attentional mechanisms. Therefore, this component might reflect the re-processing of information based on sustained short-term memory representations in the visual system until a stable target percept is created that can serve as the perceptual basis for response selection and the initiation of goal-directed behavior.
Bitsch, Florian; Berger, Philipp; Nagels, Arne; Falkenberg, Irina; Straube, Benjamin
Identifying someone else's noncooperative intentions can prevent exploitation in social interactions. Hence, the inference of another person's mental state might be most pronounced in order to improve social decision-making. Here, we tested the hypothesis that brain regions associated with Theory of Mind (ToM), particularly the right temporo-parietal junction (rTPJ), show higher neural responses when interacting with a selfish person and that the rTPJ-activity as well as cooperative tendencies will change over time. We used functional magnetic resonance imaging (fMRI) and a modified prisoner's dilemma game in which 20 participants interacted with three fictive playing partners who behaved according to stable strategies either competitively, cooperatively or randomly during seven interaction blocks. The rTPJ and the posterior-medial prefrontal cortex showed higher activity during the interaction with a competitive compared with a cooperative playing partner. Only the rTPJ showed a high response during an early interaction phase, which preceded participants increase in defective decisions. Enhanced functional connectivity between the rTPJ and the left hippocampus suggests that social cognition and learning processes co-occur when behavioral adaptation seems beneficial. © 2018 Wiley Periodicals, Inc.
Stewart, Jennifer L.; Towers, David N.; Coan, James A.; Allen, John J.B.
Relatively less right parietal activity may reflect reduced arousal and signify risk for major depressive disorder (MDD). Inconsistent findings with parietal electroencephalographic (EEG) asymmetry, however, suggest issues such as anxiety comorbidity and sex differences have yet to be resolved. Resting parietal EEG asymmetry was assessed in 306 individuals (31% male) with (n = 143) and without (n = 163) a DSM-IV diagnosis of lifetime MDD and no comorbid anxiety disorders. Past MDD+ women displayed relatively less right parietal activity than current MDD+ and MDD- women, replicating prior work. Recent caffeine intake, an index of arousal, moderated the relationship between depression and EEG asymmetry for women and men. Findings suggest that sex differences and arousal should be examined in studies of depression and regional brain activity. PMID:20525011
Gliddon, Briony L; Nguyen, Nhung V; Gunn, Priscilla A; Gleeson, Paul A; Driel, Ian R van
Here we describe a method for the isolation of intact gastric glands from mice and primary culture and transfection of mouse gastric epithelial cells. Collagenase digestion of PBS-perfused mouse stomachs released large intact gastric glands that were plated on a basement membrane matrix. The heterogeneous gland cell cultures typically contain ∼60% parietal cells. Isolated mouse parietal cells remain viable in culture for up to 5 days and react strongly with an antibody specific to the gastric H + /K + ATPase. Isolated intact mouse gastric glands and primary cultures of mouse parietal cells respond to the secretagogue, histamine. Typical morphological changes from a resting to an acid-secreting active parietal cell were observed. In resting cultures of mouse parietal cells, the H + /K + ATPase displayed a cytoplasmic punctate staining pattern consistent with tubulovesicle element structures. Following histamine stimulation, an expansion of internal apical vacuole structures was observed together with a pronounced redistribution of the H + /K + ATPase from the cytoplasm to the apical vacuoles. A reproducible procedure to express genes of interest exogenously in these cultures of mouse parietal cells was also established. This method combines recombinant adenoviral transduction with magnetic field-assisted transfection resulting in ∼30% transduced parietal cells. Adenoviral-transduced parietal cells maintain their ability to undergo agonist-induced activation. This protocol will be useful for the isolation, culture and expression of genes in parietal cells from genetically modified mice and as such will be an invaluable tool for studying the complex exocytic and endocytic trafficking events of the H + /K + ATPase which underpin the regulation of acid secretion
Shames, H; Raz, N; Levin, Netta
Posterior cortical atrophy (PCA) is a neurodegenerative syndrome in which the most pronounced pathologic involvement is in the occipito-parietal visual regions. Herein, we aimed to better define the cortical reflection of this unique syndrome using a thorough battery of behavioral and functional MRI (fMRI) tests. Eight PCA patients underwent extensive testing to map their visual deficits. Assessments included visual functions associated with lower and higher components of the cortical hierarchy, as well as dorsal- and ventral-related cortical functions. fMRI was performed on five patients to examine the neuronal substrate of their visual functions. The PCA patient cohort exhibited stereopsis, saccadic eye movements and higher dorsal stream-related functional impairments, including simultant perception, image orientation, figure-from-ground segregation, closure and spatial orientation. In accordance with the behavioral findings, fMRI revealed intact activation in the ventral visual regions of face and object perception while more dorsal aspects of perception, including motion and gestalt perception, revealed impaired patterns of activity. In most of the patients, there was a lack of activity in the word form area, which is known to be linked to reading disorders. Finally, there was evidence of reduced cortical representation of the peripheral visual field, corresponding to the behaviorally assessed peripheral visual deficit. The findings are discussed in the context of networks extending from parietal regions, which mediate navigationally related processing, visually guided actions, eye movement control and working memory, suggesting that damage to these networks might explain the wide range of deficits in PCA patients.
Stádníková, A.; Ďuďáková, L.; Skalická, P.; Valenta, Zdeněk; Filipec, M.; Jirsová, K.
Roč. 12, č. 4 (2017), č. článku e0175509. E-ISSN 1932-6203 Grant - others:GA ČR(CZ) GA17-12355S; GA MŠk(CZ) 7F14156 Institutional support: RVO:67985807 Keywords : transforming growth factor-beta2 * posterior polymorphous corneal dystrophy * corneal endothelial cells * general linear mixed-effect modelling * restricted maximum likelihood estimation Subject RIV: BB - Applied Statistics, Operational Research OBOR OECD: Statistics and probability Impact factor: 2.806, year: 2016
Luciana Vitaliano Voi Trawitzki
Full Text Available OBJETIVO: investigar a preferência mastigatória e o comportamento dos músculos mastigatórios, em crianças de 6 a 9 anos, com mordida cruzada posterior. MÉTODOS: 30 crianças foram selecionadas num serviço de Ortodontia de uma universidade pública. Após a concordância na participação no trabalho, foi realizada entrevista com a criança e seu responsável, para investigação de disfunção temporomandibular; análise da preferência mastigatória, por meio de registros em vídeo e avaliação eletromiográfica (EMG dos músculos masseter e temporal anterior, durante a mastigação solicitada, direita e esquerda, de uma goma de marcar. RESULTADOS: houve diferença significante na atividade EMG dos músculos masseter e temporal anterior entre os lados de trabalho e balanceio, porém não houve diferença estatística quando foram comparadas as atividades EMG entre os lados de mordida cruzada e não cruzada, tampouco entre os lados de preferência e não preferência mastigatória. CONCLUSÃO: na amostra estudada não se verificou assimetria funcional muscular estabelecida.PURPOSE: to investigate the masticatory preference and the behavior of masticatory muscles, in children between6 to 9-year old, with posterior crossbite. METHODS: 30 children were selected from the Orthodontical service of a public university. After consenting to take part in the study, there was an interview with the children and the parent, in order to investigate temporomandibular disorders; masticatory was analyzed through video recording and electromyographic (EMG evaluation of the masseter and anterior temporal, during the solicited mastication, on right and left, using chewing gum. RESULTS: there was a significant difference in the EMG activity of the masseter and temporal between work and balance sides, however there was no statistical differences in the comparison between crossbite side and no crossbite side, but neither between preference side and non the
Harasawa, Masamitsu; Shioiri, Satoshi
The effect of the visual hemifield to which spatial attention was oriented on the activities of the posterior parietal and occipital visual cortices was examined using functional near-infrared spectroscopy in order to investigate the neural substrates of voluntary visuospatial attention. Our brain imaging data support the theory put forth in a…
Full Text Available Posterior reversible encephalopathy syndrome (PRES is characterized by the following symptoms: seizures, impaired consciousness and/or vision, vomiting, nausea, and focal neurological signs. Diagnostic imaging includes examination by magnetic resonance (MR and computed tomography (CT, where brain edema is visualized bi-laterally and symmetrically, predominantly posteriorly, parietally, and occipitally. Case report. We presented a 73-year-old patient with the years-long medical history of hipertension and renal insufficiency, who developed PRES with the symptomatology of the rear cranium. CT and MR verified changes in the white matter involving all lobes on both sides of the brain. After a two-week treatment (antihypertensive, hypolipemic and rehydration therapy clinical improvement with no complications occurred, with complete resolution of changes in the white matter observed on CT and MR. Conclusion. PRES is a reversible syndrome in which the symptoms withdraw after several days to several weeks if early diagnosis is made and appropriate treatment started without delay.
Maia da Silva, Mari N.; Millington, Rebecca S.; Bridge, Holly; James-Galton, Merle; Plant, Gordon T.
Posterior cortical atrophy (PCA) is a syndromic diagnosis. It is characterized by progressive impairment of higher (cortical) visual function with imaging evidence of degeneration affecting the occipital, parietal, and posterior temporal lobes bilaterally. Most cases will prove to have Alzheimer pathology. The aim of this review is to summarize the development of the concept of this disorder since it was first introduced. A critical discussion of the evolving diagnostic criteria is presented and the differential diagnosis with regard to the underlying pathology is reviewed. Emphasis is given to the visual dysfunction that defines the disorder, and the classical deficits, such as simultanagnosia and visual agnosia, as well as the more recently recognized visual field defects, are reviewed, along with the evidence on their neural correlates. The latest developments on the imaging of PCA are summarized, with special attention to its role on the differential diagnosis with related conditions. PMID:28861031
Mari N. Maia da Silva
Full Text Available Posterior cortical atrophy (PCA is a syndromic diagnosis. It is characterized by progressive impairment of higher (cortical visual function with imaging evidence of degeneration affecting the occipital, parietal, and posterior temporal lobes bilaterally. Most cases will prove to have Alzheimer pathology. The aim of this review is to summarize the development of the concept of this disorder since it was first introduced. A critical discussion of the evolving diagnostic criteria is presented and the differential diagnosis with regard to the underlying pathology is reviewed. Emphasis is given to the visual dysfunction that defines the disorder, and the classical deficits, such as simultanagnosia and visual agnosia, as well as the more recently recognized visual field defects, are reviewed, along with the evidence on their neural correlates. The latest developments on the imaging of PCA are summarized, with special attention to its role on the differential diagnosis with related conditions.
Muriel Anne Lobier
Full Text Available The visual attention (VA span deficit hypothesis of developmental dyslexia posits that impaired multiple element processing can be responsible for poor reading outcomes. In VA span impaired dyslexic children, poor performance on letter report tasks is associated with reduced parietal activations for multiple letter processing. While this hints towards a non-specific, attention-based dysfunction, it is still unclear whether reduced parietal activity generalizes to other types of stimuli. Furthermore, putative links between reduced parietal activity and reduced ventral occipito-temporal (vOT in dyslexia have yet to be explored. Using fMRI, we measured brain activity in 12 VA span impaired dyslexic adults and 12 adult skilled readers while they carried out a categorization task on single or multiple alphanumeric or non-alphanumeric characters. While healthy readers activated parietal areas more strongly for multiple than single element processing (right-sided for alphanumeric and bilateral for non-alphanumeric, similar stronger multiple element right parietal activations were absent for dyslexic participants. Contrasts between skilled and dyslexic readers revealed significantly reduced right superior parietal lobule (SPL activity for dyslexic readers regardless of stimuli type. Using a priori anatomically defined ROI, we showed that neural activity was reduced for dyslexic participants in both SPL and vOT bilaterally. Finally, we used multiple regressions to test whether SPL activity could predict vOT activity in each group. In the left hemisphere, SPL activity modulated vOT activity for both normal and dyslexic readers. In contrast, in the right hemisphere, SPL activity modulated vOT activity only for dyslexic readers. These results bring critical support to the visual attention interpretation of the VA Span deficit. In addition, they offer a new insight on how deficits in automatic vOT based word recognition could arise in developmental dyslexia.
Weymar, Mathias; Bradley, Margaret M; Sege, Christopher T; Lang, Peter J
Stimulus repetition elicits either enhancement or suppression in neural activity, and a recent fMRI meta-analysis of repetition effects for visual stimuli (Kim, 2017) reported cross-stimulus repetition enhancement in medial and lateral parietal cortex, as well as regions of prefrontal, temporal, and posterior cingulate cortex. Repetition enhancement was assessed here for repeated and novel scenes presented in the context of either an explicit episodic recognition task or an implicit judgment task, in order to study the role of spontaneous retrieval of episodic memories. Regardless of whether episodic memory was explicitly probed or not, repetition enhancement was found in medial posterior parietal (precuneus/cuneus), lateral parietal cortex (angular gyrus), as well as in medial prefrontal cortex (frontopolar), which did not differ by task. Enhancement effects in the posterior cingulate cortex were significantly larger during explicit compared to implicit task, primarily due to a lack of functional activity for new scenes. Taken together, the data are consistent with an interpretation that medial and (ventral) lateral parietal cortex are associated with spontaneous episodic retrieval, whereas posterior cingulate cortical regions may reflect task or decision processes. © 2018 Society for Psychophysiological Research.
Full Text Available Posterior reversible encephalopathy syndrome (PRES is characterized by headache, altered mental status, visual loss, and seizures. PRES is associated with neuroradiological findings: white matter abnormalities, predominantly in the parieto-occipital regions of the brain. PRES has been described in association with hypertensive encephalopathy, eclampsia, renal failure, or following immunosuppressive or anticancer therapy. We report a case of PRES in a severe preeclampsia occurring in the late postpartum period, with suppressed plasma aldosterone levels and plasma renin activity. These laboratory abnormalities may be due to an apparent mineralocorticoid excess syndrome.
Jantsch, H.; Greene, R.; Lechner, G.; Mavritz, W.; Pichler, W.; Winkler, M.; Zadrobilek, E.
This paper describes bedside radiographs with localized intercostal bulging as the sole indication of tension pneumothorax in six patients with acute deterioration in gas exchange. Relief of the pneumothorax was followed by a rush of gas from the tension space and a prompt improvement in gas exchange. The authors concluded the regional intercostal bulging of the parietal pleura may be the sole indicator of life-threatening tension pneumothorax in patients on mechanical ventilation
Cohen, H; McCabe, C; Harris, N; Hall, J; Lewis, J; Blake, D R
Unusual symptoms such as digit misidentification and neglect-like phenomena have been reported in complex regional pain syndrome (CRPS), which we hypothesized could be explained by parietal lobe dysfunction. Twenty-two patients with chronic CRPS attending an in-patient rehabilitation programme underwent standard neurological examination followed by clinical assessment of parietal lobe function and detailed sensory testing. Fifteen (68%) patients had evidence of parietal lobe dysfunction. Six (27%) subjects failed six or more test categories and demonstrated new clinical signs consistent with their parietal testing impairments, which were impacting significantly on activities of daily living. A higher incidence was noted in subjects with >1 limb involvement, CRPS affecting the dominant side and in left-handed subjects. Eighteen patients (82%) had mechanical allodynia covering 3-57.5% of the body surface area. Allochiria (unilateral tactile stimulation perceived only in the analogous location on the opposite limb), sensory extinction (concurrent bilateral tactile stimulation perceived only in one limb), referred sensations (unilateral tactile stimulation perceived concurrently in another discrete body area) and dysynchiria (unilateral non-noxious tactile stimulation perceived bilaterally as noxious) were present in some patients. Greater extent of body surface allodynia was correlated with worse parietal function (Spearman's rho = -0.674, p = 0.001). In patients with chronic CRPS, detailed clinical examination may reveal parietal dysfunction, with severity relating to the extent of allodynia. © 2012 European Federation of International Association for the Study of Pain Chapters.
Fernández-de-Las-Peñas, César; Cuadrado, María Luz; Arendt-Nielsen, Lars; Ge, Hong-You; Pareja, Juan A
To investigate whether cross-sectional area (CSA) of the suboccipital muscles was associated with active trigger points (TrPs) in chronic tension-type headache (CTTH). Magnetic resonance imaging (MRI) of the cervical spine was performed in 11 females with CTTH aged from 26 to 50 yrs old. CSA for both rectus capitis posterior minor (RCPmin) and rectus capitis posterior major (RCPmaj) muscles were measured from axial T1-weighted images, using axial MRI slices aligned parallel to the C2/3 intervertebral disc. A headache diary was kept for 4 wks to record the pain history. TrPs in the suboccipital muscle were identified by eliciting referred pain to palpation, and increased referred pain with muscle contraction. TrPs were considered active if the elicited referred pain reproduced the head pain pattern and features of the pattern seen during spontaneous headache attacks. Active TrPs were found in six patients (55%), whereas the remaining five patients showed latent TrPs. CSA of the RCPmin was significantly smaller (F = 13.843; P = 0.002) in the patients with active TrPs (right side: 55.9 +/- 4.4 mm; left side: 61.1 +/-: 3.8 mm) than in patients with latent TrPs (right side: 96.9 +/- 14.4 mm; left side: 88.7 +/- 9.7 mm). No significant differences were found for CSA of the RCPmaj between the patients with either active or latent TrP (P > 0.5). It seems that muscle atrophy in the RCPmin, but not in the RCPmaj, was associated with suboccipital active TrPs in CTTH, although studies with larger sample sizes are now required. It may be that nociceptive inputs in active TrPs could lead to muscle atrophy of the involved muscles. Muscle disuse or avoidance behavior can also be involved in atrophy.
Park, Kyue-Nam; Kwon, Oh-Yun; Kim, Su-Jung; Kim, Si-Hyun
Although unilateral posterior neck pain (UPNP) is more prevalent than central neck pain, little is known about how UPNP affects neck motion and the muscle activation pattern during prone neck extension. To investigate whether deviation in neck motion and asymmetry of activation of the bilateral cervical paraspinal muscles occur during prone neck extension in subjects with UPNP compared to subjects without UPNP. This study recruited 20 subjects with UPNP and 20 age- and sex-matched control subjects without such pain. Neck motion and muscle onset time during prone neck extension were measured using a three-dimensional motion-analysis system and surface electromyography. The deviation during prone neck extension was greater in the UPNP group than in the controls (p cervical extensor muscle activation in the UPNP group was significantly delayed on the painful side during prone neck extension (p cervical extensors, triggering a need for specific evaluation and exercises in the management of patients with UPNP.
Li, Siyao; Cai, Ying; Liu, Jing; Li, Dawei; Feng, Zifang; Chen, Chuansheng; Xue, Gui
Mounting evidence suggests that multiple mechanisms underlie working memory capacity. Using transcranial direct current stimulation (tDCS), the current study aimed to provide causal evidence for the neural dissociation of two mechanisms underlying visual working memory (WM) capacity, namely, the scope and control of attention. A change detection task with distractors was used, where a number of colored bars (i.e., two red bars, four red bars, or two red plus two blue bars) were presented on both sides (Experiment 1) or the center (Experiment 2) of the screen for 100ms, and participants were instructed to remember the red bars and to ignore the blue bars (in both Experiments), as well as to ignore the stimuli on the un-cued side (Experiment 1 only). In both experiments, participants finished three sessions of the task after 15min of 1.5mA anodal tDCS administered on the right prefrontal cortex (PFC), the right posterior parietal cortex (PPC), and the primary visual cortex (VC), respectively. The VC stimulation served as an active control condition. We found that compared to stimulation on the VC, stimulation on the right PPC specifically increased the visual WM capacity under the no-distractor condition (i.e., 4 red bars), whereas stimulation on the right PFC specifically increased the visual WM capacity under the distractor condition (i.e., 2 red bars plus 2 blue bars). These results suggest that the PPC and PFC are involved in the scope and control of attention, respectively. We further showed that compared to central presentation of the stimuli (Experiment 2), bilateral presentation of the stimuli (on both sides of the fixation in Experiment 1) led to an additional demand for attention control. Our results emphasize the dissociated roles of the frontal and parietal lobes in visual WM capacity, and provide a deeper understanding of the neural mechanisms of WM. Copyright © 2017 Elsevier Inc. All rights reserved.
Carp, Joshua; Fitzgerald, Kate Dimond; Taylor, Stephan F; Weissman, Daniel H
In functional magnetic resonance imaging (fMRI) studies, researchers often attempt to ensure that group differences in brain activity are not confounded with group differences in mean reaction time (RT). However, even when groups are matched for performance, they may differ in terms of the RT-BOLD relationship: the degree to which brain activity varies with RT on a trial-by-trial basis. Group activation differences might therefore be influenced by group differences in the relationship between brain activity and time on task. Here, we investigated whether correcting for this potential confound alters group differences in brain activity. Specifically, we reanalyzed data from a functional MRI study of response conflict in children and adults, in which conventional analyses indicated that conflict-related activity did not differ between groups. We found that the RT-BOLD relationship was weaker in children than in adults. Consequently, after removing the effect of RT on brain activity, children exhibited greater conflict-related activity than adults in both the posterior medial prefrontal cortex and the right dorsolateral prefrontal cortex. These results identify the RT-BOLD relationship as an important potential confound in fMRI studies of group differences. They also suggest that the magnitude of the RT-BOLD relationship may be a useful biomarker of brain maturity. Copyright © 2011 Elsevier Inc. All rights reserved.
Silvestri, S; Lepri, E; Dall'Aglio, C; Marchesi, M C; Vitellozzi, G
Nuclear glycogen inclusions occur infrequently in pathologic conditions but also in normal human and animal tissues. Their function or significance is unclear. To the best of the authors' knowledge, no reports of nuclear glycogen inclusions in canine parietal cells exist. After initial observations of nuclear inclusions/pseudoinclusions during routine histopathology, the authors retrospectively examined samples of gastric mucosa from dogs presenting with gastrointestinal signs for the presence of intranuclear inclusions/pseudoinclusions and determined their composition using histologic and electron-microscopic methods. In 24 of 108 cases (22%), the authors observed various numbers of intranuclear inclusions/pseudoinclusions within scattered parietal cells. Nuclei were characterized by marked karyomegaly and chromatin margination around a central optically empty or slightly eosinophilic area. The intranuclear inclusions/pseudoinclusions stained positive with periodic acid-Schiff (PAS) and were diastase sensitive, consistent with glycogen. Several PAS-positive/diastase-sensitive sections were further examined by transmission electron microscopy, also using periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP) staining to identify polysaccharides. Ultrastructurally, the nuclear inclusions were composed of electron-dense particles that were not membrane bound, without evidence of nuclear membrane invaginations or cytoplasmic organelles in the nuclei, and positive staining with PA-TCH-SP, confirming a glycogen composition. No cytoplasmic glycogen deposits were observed, suggesting that the intranuclear glycogen inclusions were probably synthesized in loco. Nuclear glycogen inclusions were not associated with gastritis or colonization by Helicobacter-like organisms ( P > .05). Our findings suggest that nuclear glycogen inclusions in canine parietal cells could be an incidental finding. Nevertheless, since nuclear glycogen is present in several pathologic
Dent, Kevin; Lestou, Vaia; Humphreys, Glyn W
It has been argued that area hMT+/V5 in humans acts as a motion filter, enabling targets defined by a conjunction of motion and form to be efficiently selected. We present data indicating that (a) damage to parietal cortex leads to a selective problem in processing motion-form conjunctions, and (b) that the presence of a structurally and functional intact hMT+/V5 is not sufficient for efficient search for motion-form conjunctions. We suggest that, in addition to motion-processing areas (e.g., hMT+/V5), the posterior parietal cortex is necessary for efficient search with motion-form conjunctions, so that damage to either brain region may bring about deficits in search. We discuss the results in terms of the involvement of the posterior parietal cortex in the top-down guidance of search or in the binding of motion and form information.
Sina A Gharib
Full Text Available Very little is known about the function of glomerular parietal epithelial cells (PECs. In this study, we performed genome-wide expression analysis on PEC-enriched capsulated vs. PEC-deprived decapsulated rat glomeruli to determine the transcriptional state of PECs under normal conditions. We identified hundreds of differentially expressed genes that mapped to distinct biologic modules including development, tight junction, ion transport, and metabolic processes. Since developmental programs were highly enriched in PECs, we characterized several of their candidate members at the protein level. Collectively, our findings confirm that PECs are multifaceted cells and help define their diverse functional repertoire.
Kushner, M.J.; Luken, M.G. III
CT demonstrated posterior fossa epidural hematoma in three patients with head trauma in whom this diagnosis was not clinically apparent. No patient was in stupor or coma and no patient experienced a lucid interval. Only one patient had signs referable to the posterior fossa. Two patients had occipital skull fracture disclosed by plain radiographs. CT revealed a unilateral biconvex hematoma in two cases, and a bilateral hematoma with supratentorial extension in the third. All patients underwent suboccipital craniectomy and recovered. Therapeutic success in these cases was facilitated by early CT and the rapid disclosure of the unsuspected posterior fossa lesions. CT showing contiguous hematoma below and above the tentorium cerebelli after posterior head trauma is highly suggestive of epidural hematoma arising from the posterior fossa. (orig.)
Full Text Available Tien-Yu Chen,1 Chun-Yen Chen,1,3 Che-Hung Yen,2,3 Shin-Chang Kuo,1,3 Yi-Wei Yeh,1,3 Serena Chang,1 San-Yuan Huang1,31Department of Psychiatry, 2Department of Neurology, Tri-Service General Hospital, School of Medicine, National Defense Medical Center, 3Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, Republic of ChinaAbstract: Gerstmann’s syndrome encompasses the tetrad of finger agnosia, agraphia, acalculia, and right-left confusion. An elderly man with a history of several cardiovascular diseases was initially brought to the psychiatric outpatient department by his family because of worsening of recent memory, executive function, and mixed anxious-depressive mood. Gerstmann’s syndrome without obvious motor function impairment and dementia-like features could be observed at first. Emergent brain computed tomography scan revealed new left-middle cerebral artery infarction over the left posterior parietal lobe. This case reminds us that acute cerebral infarction involving the parietal lobe may present as Gerstmann’s syndrome accompanied by cognitive decline mimicking dementia. As a result, emergent organic workups should be arranged, especially for elderly patients at high risk for cerebral vascular accident.Keywords: Gerstmann’s syndrome, dementia, parietal lobe infarction
Wilkes, J.M.; Kajimura, M.; Scott, D.R.; Hersey, S.J.; Sachs, G.
Isolated rabbit gastric glands were used to study the nature of the muscarinic cholinergic responses of parietal cells. Carbachol stimulation of acid secretion, as measured by the accumulation of aminopyrine, was inhibited by the M1 antagonist, pirenzepine, with an IC50 of 13 microM; by the M2 antagonist, 11,2-(diethylamino)methyl-1 piperidinyl acetyl-5,11-dihydro-6H-pyrido 2,3-b 1,4 benzodiazepin-6-one (AF-DX 116), with an IC50 of 110 microM; and by the M1/M3 antagonist, diphenyl-acetoxy-4-methylpiperidinemethiodide, with an IC50 of 35 nM. The three antagonists displayed equivalent IC50 values for the inhibition of carbachol-stimulated production of 14CO2 from radiolabeled glucose, which is a measure of the turnover of the H,K-ATPase, the final step of acid secretion. Intracellular calcium levels were measured in gastric glands loaded with FURA 2. Carbachol was shown to both release calcium from an intracellular pool and to promote calcium entry across the plasma membrane. The calcium entry was inhibitable by 20 microM La3+. The relative potency of the three muscarinic antagonists for inhibition of calcium entry was essentially the same as for inhibition of acid secretion or pump related glucose oxidation. Image analysis of the glands showed the effects of carbachol, and of the antagonists, on intracellular calcium were occurring largely in the parietal cell. The rise in cell calcium due to release of calcium from intracellular stores was inhibited by 4-DAMP with an IC50 of 1.7 nM, suggesting that the release pathway was regulated by a low affinity M3 muscarinic receptor or state; Ca entry and acid secretion are regulated by a high affinity M3 muscarinic receptor or state, inhibited by higher 4-DAMP concentrations, suggesting that it is the steady-state elevation of Ca that is related to parietal cell function rather than the [Ca]i transient
Li, Xin; Wang, Wenxiao; Wang, Ailin; Li, Peng; Zhang, Junying; Tao, Wuhai; Zhang, Zhanjun
Hypertension is related with cognitive decline in the elderly. The frontal-parietal executive system plays an important role in cognitive aging and is also vulnerable to damage in elderly patients with hypertension. Examination of the brain's functional characteristics in frontal-parietal regions of hypertension is likely to be important for understanding the neural mechanisms of hypertension's effect on cognitive aging. We address this issue by comparing hypertension and control-performers in a functional MRI study. Twenty-eight hypertensive patients and 32 elderly controls were tested with n-back task with two load levels. The hypertensive patients exhibited worse executive and memory abilities than control subjects. The patterns of brain activation changed under different working memory loads in the hypertensive patients, who exhibited reduced activation only in the precentral gyrus under low loads and reduced activation in the middle frontal gyrus, left medial superior frontal gyrus and right precuneus under high loads. Thus, more regions of diminished activation were observed in the frontal and parietal regions with increasing task difficulty. More importantly, we found that lower activation in changed frontal and parietal regions was associated with worse cognitive function in high loads. The results demonstrate the relationship between cognitive function and frontoparietal functional activation in hypertension and their relevance to cognitive aging risk. Our findings provide a better understanding of the mechanism of cognitive decline in hypertension and highlight the importance of brain protection in hypertension.
Wang, Chao; Shen, Zhujing; Huang, Peiyu; Qian, Wei; Yu, Xinfeng; Sun, Jianzhong; Yu, Hualiang; Yang, Yihong; Zhang, Minming
Compared to nonsmokers, smokers exhibit a number of potentially important differences in regional brain function. However, little is known about the associations between the local spontaneous brain activity and smoking cessation treatment outcomes. In the present analysis, we aimed to evaluate whether the local features of spontaneous brain activity prior to the target quit date was associated with the smoking cessation outcomes. All the participants underwent magnetic resonance imaging scans and smoking-related behavioral assessments. After a 12-week treatment with varenicline, 23 smokers succeeded in quitting smoking and 32 failed. Smokers underwent functional magnetic resonance imaging (fMRI) scanning prior to an open label smoking cessation treatment trial. Regional homogeneity (ReHo) was used to measure spontaneous brain activity, and whole-brain voxel-wise comparisons of ReHo were performed to detect brain regions with altered spontaneous brain activity between relapser and quitter groups. After controlling for potentially confounding factors including years of education, years smoked, cigarettes smoked per day and FTND score as covariates, compared to quitters, relapsers displayed significantly decreased ReHo in bilateral posterior cingulate cortex (PCC), as well as increased ReHo in left superior temporal gyrus (STG). These preliminary results suggest that regional brain function variables may be promising predictors of smoking relapse. This study provided novel insights into the neurobiological mechanisms underlying smoking relapse. A deeper understanding of the neurobiological mechanisms associated with relapse may result in novel pharmacological and behavioral interventions.
Shakespeare, Timothy J; Kaski, Diego; Yong, Keir X X; Paterson, Ross W; Slattery, Catherine F; Ryan, Natalie S; Schott, Jonathan M; Crutch, Sebastian J
The clinico-neuroradiological syndrome posterior cortical atrophy is the cardinal 'visual dementia' and most common atypical Alzheimer's disease phenotype, offering insights into mechanisms underlying clinical heterogeneity, pathological propagation and basic visual phenomena (e.g. visual crowding). Given the extensive attention paid to patients' (higher order) perceptual function, it is surprising that there have been no systematic analyses of basic oculomotor function in this population. Here 20 patients with posterior cortical atrophy, 17 patients with typical Alzheimer's disease and 22 healthy controls completed tests of fixation, saccade (including fixation/target gap and overlap conditions) and smooth pursuit eye movements using an infrared pupil-tracking system. Participants underwent detailed neuropsychological and neurological examinations, with a proportion also undertaking brain imaging and analysis of molecular pathology. In contrast to informal clinical evaluations of oculomotor dysfunction frequency (previous studies: 38%, current clinical examination: 33%), detailed eyetracking investigations revealed eye movement abnormalities in 80% of patients with posterior cortical atrophy (compared to 17% typical Alzheimer's disease, 5% controls). The greatest differences between posterior cortical atrophy and typical Alzheimer's disease were seen in saccadic performance. Patients with posterior cortical atrophy made significantly shorter saccades especially for distant targets. They also exhibited a significant exacerbation of the normal gap/overlap effect, consistent with 'sticky fixation'. Time to reach saccadic targets was significantly associated with parietal and occipital cortical thickness measures. On fixation stability tasks, patients with typical Alzheimer's disease showed more square wave jerks whose frequency was associated with lower cerebellar grey matter volume, while patients with posterior cortical atrophy showed large saccadic intrusions
Washington, Stuart D; VanMeter, John W
The default mode network (DMN) supports self-referential thought processes important for successful socialization including: theory-of-mind, episodic memory, and prospection. Connectivity between DMN's nodes, which are distributed between the frontal, temporal, and parietal lobes, change with age and may continue changing into adulthood. We have previously explored the maturation of functional connections in the DMN as they relate to autism spectrum disorder (ASD) in children 6 to 18 years of age. In this chapter, we refine our earlier study of DMN functional maturation by focusing on the development of inter-nodal connectivity in a larger pool of typically developing people 6 to 25 years of age (mean = 13.22 years ± 5.36 s.d.; N = 36; 42% female). Correlations in BOLD activity (Fisher's Z) between ROIs revealed varying strengths of functional connectivity between regions, the strongest of which was between the left and right inferior parietal lobules or IPLs (Z = 0.62 ± 0.25 s.d.) and the weakest of which was between the posterior cingulate cortex (PCC) and right middle temporal gyrus or MTG (Z = 0.06 ± 0.22 s.d.). Further, connectivity between two pairs of DMN nodes significantly increased as a quadratic function of age ( p maturational trajectory.
Friedland, T.F.; Budinger, T.F.; Jaqust, W.J.; Yano, Y.; Huesman, R.H.; Knittel, B.; Koss, E.; Ober, B.A.
The anatomical and chemical features of Alzheimer's disease (AD) are not distributed evenly throughout the brain. However, the nature of this focality has not been well established in vivo. Dynamic studies using the Donner 280-Crystal Positron Tomograph with (F-18)2-fluorodeoxyglucose were performed in 17 subjects meeting current research criteria for AD, and in 7 healthy age-matched control subjects. Glucose metabolic rates in the temporal-parietal cortex are 27% lower in AD than in controls. Ratios of activity density reveal consistently lower metabolic rates in temporal-parietal than frontal cortex in the AD group, while healthy aged subjects have equal metabolic rates in the two areas. Similar findings have been reported by other laboratories. A major finding is a striking lateral asymmetry of cortical metabolism in AD which does not favor either hemisphere. (The asymmetry is 13% in the AD group, 3% in controls, p<.005.) This has not been previously reported in AD. The consistency with which anterior-posterior metabolic differences are found in AD suggests that the focality of the metabolic changes may be used to develop a noninvasive diagnostic test for the disorder. The metabolic asymmetry in AD may be compared to the clinical and pathological asymmetry found in Creutzfeldt-Jakob disease, and may represent an additional link between AD and the subacute spongiform encephalopathies
Cohen, M.X.; Weidacker, K.S.; Tankink, J.; Scholte, H.S.; Rouw, R.
Grapheme-color synesthesia is a condition in which seeing letters and numbers produces sensations of colors (e.g., the letter R may elicit a sky-blue percept). Recent evidence implicates posterior parietal areas, in addition to lower-level sensory processing regions, in the neurobiological
Horschig, J.M.; Oosterheert, W.; Oostenveld, R.; Jensen, O.
Here we report that the modulation of alpha activity by covert attention can be used as a control signal in an online brain-computer interface, that it is reliable, and that it is robust. Subjects were instructed to orient covert visual attention to the left or right hemifield. We decoded the
Meeuwissen, E.B.; Takashima, A.; Fernandez, G.S.E.; Jensen, O.
It is becoming increasingly clear that demanding cognitive tasks rely on an extended network engaging task-relevant areas and, importantly, disengaging task-irrelevant areas. Given that alpha activity (8-12 Hz) has been shown to reflect the disengagement of task-irrelevant regions in attention and
Meeuwissen, E.B.; Takashima, A.; Fernandez, G.S.E.; Jensen, O.
It is becoming increasingly clear that demanding cognitive tasks rely on an extended network engaging task-relevant areas and, importantly, disengaging task-irrelevant areas. Given that alpha activity (8–12 Hz) has been shown to reflect the disengagement of task-irrelevant regions in attention and
Full Text Available The planning of goal-directed arm reaching movements is associated with activity in the dorsal parieto-frontal cortex, within which multiple regions subserve the integration of arm- and target-related sensory signals to encode a motor goal. Surprisingly, many of these regions show sustained activity during reach preparation even when target location is not specified, i.e., when a motor goal cannot be unambiguously formed. The functional role of these non-spatial preparatory signals remains unresolved. Here this process was investigated in humans by comparing reach preparatory activity in the presence or absence of information regarding upcoming target location. In order to isolate the processes specific to reaching and to control for visuospatial attentional factors, the reaching task was contrasted to a finger movement task. Functional MRI and electroencephalography (EEG were used to characterize the spatio-temporal pattern of reach-related activity in the parieto-frontal cortex. Reach planning with advance knowledge of target location induced robust blood oxygenated level dependent and EEG responses across parietal and premotor regions contralateral to the reaching arm. In contrast, reach preparation without knowledge of target location was associated with a significant BOLD response bilaterally in the parietal cortex. Furthermore, EEG alpha- and beta-band activity was restricted to parietal scalp sites, the magnitude of the latter being correlated with reach reaction times. These results suggest an intermediate stage of sensorimotor transformations in bilateral parietal cortex when target location is not specified.
Samuel William Cheadle
Full Text Available Imaging evidence shows that separate subdivisions of parietal cortex, in and around the intraparietal sulcus (IPS, are engaged when stimuli are grouped according to colour and to motion (Zeki and Stutters 2013. Since grouping is an essential step in the formation of concepts, we wanted to learn whether parietal cortex is also engaged in the formation of concepts according to these two attributes. Using functional magnetic resonance imaging (fMRI, and choosing the recognition of concept-based colour or motion stimuli as our paradigm, we found that there was strong concept-related activity in and around the intraparietal sulcus (IPS, a region whose homologue in the macaque monkey is known to receive direct but segregated anatomical inputs from V4 and V5. Parietal activity related to colour concepts was juxtaposed but did not overlap with activity related to motion concepts, thus emphasizing the continuation of the segregation of colour and motion into the conceptual system. Concurrent retinotopic mapping experiments showed that within the parietal cortex, concept-related activity increases within later stage IPS areas.
Full Text Available Abstract Background The reversible posterior leukoencephalopathy syndrome is a clinical/radiological syndrome characterized by headache, seizures, impaired vision, acute hypertension, and typical magnetic resonance imaging findings. There are several reports in the literature that depict its occurrence in cancer patients. The list of common anticancer and supportive care drugs that predispose to reversible posterior leukoencephalopathy syndrome is expanding and includes not only a large number of chemotherapeutic agents but also an increased number of new targeted drugs, particularly angiogenesis inhibitors such as bevacizumab,sorefenib and sunitinib. Pazopanib is an oral tyrosine kinase inhibitor targeting vascular endothelial growth factor receptor, platelet-derived growth factor receptor, and c-Kit which after a positive phase III randomized clinical trial in patients with advanced renal cell cancer received FDA approval for the treatment of advanced renal cell carcinoma. Until now no cases of reversible posterior leukoencephalopathy syndrome induced by pazopanib have been reported. Case report We present the case of a 40 years old female patient with heavily pre-treated metastatic renal cell carcinoma who received pazopanib as salvage treatment. After 21 days of pazopanib therapy the patient referred to the emergency department with epileptic seizure, impaired vision at both eyes and headache. MRI of the brain revealed subcortical oedema at the occipital and parietal lobes bilaterally. She was treated with anticonvulsants, i.v. administration of mannitol and antihypertensives and she recovered completely from her symptoms and was discharged on the tenth hospital day. A brain MRI performed 3 weeks after showed that the subcortical oedema had been subsided. Conclusion In conclusion this is the first case of pazopanib induced reversible posterior leukoencephalopathy syndrome. Although usually reversible, this syndrome is a serious and
Chelis, Leonidas; Kakolyris, Stylianos; Souftas, Vasilios; Amarantidis, Kiriakos; Xenidis, Nikolaos; Chamalidou, Eleni; Dimopoulos, Prokopios; Michailidis, Prodromos; Christakidis, Evagelos; Prassopoulos, Panagiotis
The reversible posterior leukoencephalopathy syndrome is a clinical/radiological syndrome characterized by headache, seizures, impaired vision, acute hypertension, and typical magnetic resonance imaging findings. There are several reports in the literature that depict its occurrence in cancer patients. The list of common anticancer and supportive care drugs that predispose to reversible posterior leukoencephalopathy syndrome is expanding and includes not only a large number of chemotherapeutic agents but also an increased number of new targeted drugs, particularly angiogenesis inhibitors such as bevacizumab,sorefenib and sunitinib. Pazopanib is an oral tyrosine kinase inhibitor targeting vascular endothelial growth factor receptor, platelet-derived growth factor receptor, and c-Kit which after a positive phase III randomized clinical trial in patients with advanced renal cell cancer received FDA approval for the treatment of advanced renal cell carcinoma. Until now no cases of reversible posterior leukoencephalopathy syndrome induced by pazopanib have been reported. We present the case of a 40 years old female patient with heavily pre-treated metastatic renal cell carcinoma who received pazopanib as salvage treatment. After 21 days of pazopanib therapy the patient referred to the emergency department with epileptic seizure, impaired vision at both eyes and headache. MRI of the brain revealed subcortical oedema at the occipital and parietal lobes bilaterally. She was treated with anticonvulsants, i.v. administration of mannitol and antihypertensives and she recovered completely from her symptoms and was discharged on the tenth hospital day. A brain MRI performed 3 weeks after showed that the subcortical oedema had been subsided. In conclusion this is the first case of pazopanib induced reversible posterior leukoencephalopathy syndrome. Although usually reversible, this syndrome is a serious and potentially life threatening adverse effect, if untreated, that should
Gerlach, Christian; Aaside, C T; Humphreys, G W
We report evidence from a PET activation study that the inferior occipital gyri (likely to include area V2) and the posterior parts of the fusiform and inferior temporal gyri are involved in the integration of visual elements into perceptual wholes (single objects). Of these areas, the fusiform a......) that perceptual and memorial processes can be dissociated on both functional and anatomical grounds. No evidence was obtained for the involvement of the parietal lobes in the integration of single objects....
Full Text Available Alzheimer’s disease (AD and its prodromal state amnestic mild cognitive impairment (aMCI are characterized by widespread abnormalities in inter-areal white matter fiber pathways and parallel disruption of default mode network (DMN resting state functional and effective connectivity. In healthy subjects, DMN and task positive network interaction are modulated by the thalamus suggesting that abnormal task-based DMN deactivation in aMCI may be a consequence of impaired thalamo-cortical white matter circuitry. Thus, this article uses a multimodal approach to assess white matter integrity between thalamus and DMN components and associated effective connectivity in healthy controls (HCs relative to aMCI patients. Twenty-six HC and 20 older adults with aMCI underwent structural, functional and diffusion MRI scanning using the high angular resolution diffusion-weighted acquisition protocol. The DMN of each subject was identified using independent component analysis (ICA and resting state effective connectivity was calculated between thalamus and DMN nodes. White matter integrity changes between thalamus and DMN were investigated with constrained spherical deconvolution (CSD tractography. Significant structural deficits in thalamic white matter projection fibers to posterior DMN components posterior cingulate cortex (PCC and lateral inferior parietal lobe (IPL were identified together with significantly reduced effective connectivity from left thalamus to left IPL. Crucially, impaired thalamo-cortical white matter circuitry correlated with memory performance. Disrupted thalamo-cortical structure was accompanied by significant reductions in IPL and PCC cortico-cortical effective connectivity. No structural deficits were found between DMN nodes. Abnormal posterior DMN activity may be driven by changes in thalamic white matter connectivity; a view supported by the close anatomical and functional association of thalamic nuclei effected by AD pathology and
Szpunar, Karl K; St Jacques, Peggy L; Robbins, Clifford A; Wig, Gagan S; Schacter, Daniel L
In everyday life, people adaptively prepare for the future by simulating dynamic events about impending interactions with people, objects and locations. Previous research has consistently demonstrated that a distributed network of frontal-parietal-temporal brain regions supports this ubiquitous mental activity. Nonetheless, little is known about the manner in which specific regions of this network contribute to component features of future simulation. In two experiments, we used a functional magnetic resonance (fMR)-repetition suppression paradigm to demonstrate that distinct frontal-parietal-temporal regions are sensitive to processing the scenarios or what participants imagined was happening in an event (e.g., medial prefrontal, posterior cingulate, temporal-parietal and middle temporal cortices are sensitive to the scenarios associated with future social events), people (medial prefrontal cortex), objects (inferior frontal and premotor cortices) and locations (posterior cingulate/retrosplenial, parahippocampal and posterior parietal cortices) that typically constitute simulations of personal future events. This pattern of results demonstrates that the neural substrates of these component features of event simulations can be reliably identified in the context of a task that requires participants to simulate complex, everyday future experiences.
Cynthia Gayle Wible
Full Text Available A framework is described for understanding the schizophrenic syndrome at the brain systems level. It is hypothesized that over-activation of dynamic gesture and social perceptual processes in the temporal-parietal occipital junction (TPJ, posterior superior temporal sulcus (PSTS and surrounding regions produce the syndrome (including positive and negative symptoms, their prevalence, prodromal signs and cognitive deficits. Hippocampal system hyper-activity and atrophy have been consistently found in schizophrenia. Hippocampal activity is highly related to activity in the TPJ and may be a source of over-excitation of the TPJ and surrounding regions. Strong evidence for this comes from in-vivo recordings in humans during psychotic episodes. The TPJ and PSTS play a key role in the perception (and production of dynamic social, emotional and attentional gestures for the self and others (e.g., body/face/eye gestures, audiovisual speech, prosody. The single cell representation of dynamic gestures is multimodal (auditory, visual, tactile, matching the predominant hallucinatory categories in schizophrenia. Inherent in the single cell perceptual signal of dynamic gesture representations is a computation of intention, agency, and anticipation or expectancy (for the self and others. The neurons are also tuned or biased to detect threat related emotions. Abnormal over-activation in this system could produce the conscious hallucination of a voice (audiovisual speech, person or a touch. Over-activation could interfere with attentional/emotional gesture perception and production (negative symptoms. It could produce the unconscious feeling of being watched, followed or of a social situation unfolding along with accompanying perception of intent and agency inherent in those representations (delusions. Cognitive disturbances in attention, predictive social processing, agency, working memory, and a bias toward the perception of threat would also be predicted.
Eddy, Clare M; Cavanna, Andrea E; Rickards, Hugh E; Hansen, Peter C
Tourette syndrome (TS) is a neurodevelopmental disorder characterized by tics, repetitive movements and vocalizations which are prompted by a sensory-cognitive premonitory urge. Complex tics include environmentally dependent social behaviors such as echoing of other people's speech and actions. Recent studies have suggested that adults with TS can show differences to controls in Theory of Mind (ToM): reasoning about mental states (e.g. beliefs, emotions). In this study, twenty-five adults with uncomplicated TS (no co-morbid disorders, moderate tic severity), and twenty-five healthy age and gender matched controls were scanned with fMRI during an established ToM task. Neural activity was contrasted across ToM trials involving reasoning about false-belief, and matched trials requiring judgments about physical states rather than mental states. Contrasting task conditions uncovered differential fMRI activation in TS during ToM involving the right temporo-parietal junction (TPJ), right amygdala and posterior cingulate. Further analysis revealed that activity within the right TPJ as localised by this task covaried with the severity of symptoms including echophenomena, impulse control problems and premonitory urges in TS. Amygdala activation was also linked to premonitory urges, while activity in the left TPJ during ToM was linked to ratings of non-obscene socially inappropriate symptoms. These findings indicate that patients with TS exhibit atypical functional activation within key neural substrates involved in ToM. More generally, our data could highlight an important role for TPJ dysfunction in driving compulsive behaviors. Copyright © 2016 Elsevier Ltd. All rights reserved.
José Manuel Díaz Fernández
Full Text Available Se realizó un estudio descriptivo, longitudinal y prospectivo de 22 pacientes en los que se utilizó el injerto parietal autógeno para reconstruir defectos del cráneo, en los servicios de Cirugía Maxilofacial y Neurocirugía del Hospital Clinicoquirúrgico Docente "Saturnino Lora", de Santiago de Cuba, desde 1988 hasta 1991. El método de extracción del injerto con división in situ resultó el más empleado y el que ofreció las mejores posibilidades de reconstrucción en cuanto a forma, volumen y flexibilidad, por lo que se recomienda en los defectos pequeños y medianos, sobre todo de la región frontal y áreas adyacentes, donde el contorno y la simetría son los 2 aspectos fundamentales que se deben conseguir. El método de división, in vitro se utilizó en las reconstrucciones de las deformidades de grandes dimensiones, particularmente en aquellas que no incluían la frente. El índice de complicaciones fue bajoIt was carried out a descriptive, longitudinal and prospective study of 22 patients in whom an autogenous parietal graft was used to reconstruct cranial defects at the Maxillofacial Surgery and Neurosurgery Department of the "Saturnino Lora" Clinical and Surgical Teaching Hospital, in Santiago de Cuba, from 1988 to 1991. The graft extraction method with division in situ was the most used and offered the best possibilities for reconstruction as regards form, volume and flexibility. Therefore, it is recommended for small and medium defects, particularly of the frontal region and adjacent areas, where contour and symmetry are the two fundamental aspects to be taken into consideration. The method of division in vitro was used to reconstruct large deformities, specially those in which the forehead was not included. The complications index was low
Full Text Available The data presented illustrated the in vitro anti-proliferative effect of the PSG toxin from the cuttlefish, Sepia pharaonis. The cytostatic potentials of the PSG toxin were determined by the lymphocyte migration inhibition assay. The PSG toxin (50 μg/ml exhibited commendable inhibition of the migration of lymphocytes across the agarose gel matrix under the presence of lipopolysaccharide mitogen, with a mean migration index of 0.625. The cytotoxicity of the PSG toxin against selected cancer cell lines was determined using the MTT assay. The PSG toxin exhibited dose-dependent cytotoxicity against the MCF-7 breast cancer cells followed by KB (oral, HeLa (cervical and A549 (lung cancer cell lines. The PSG toxin also exhibited proportional release of LDH leakage by mitochondrial damage with an IC50 of 13.85 μM against MCF-7 breast cancer cells. The in vitro anticancer activity of the PSG toxin against the selected cell lines was evaluated by Karthik et al. (2017 .
Moure Romanillo, Alfonso
Full Text Available This study overlaps in part with a communication presented to the «Colloque International d'Art Parietal Paléolithique» held at Perigueux-Le Thot in december 1984. The technological responses contained in a decorated zone of the cave of Tito Bustillo are analyzed, as well as the activities carried out on living floors related to the preparation and completion of the parietal art.
El trabajo coincide parcialmente con la comunicación presentada al «Colloque International d'Art Parietal Paléolithique» celebrado en Perigueux-Le Thot, en diciembre de 1984. Se analizan las respuestas tecnológicas contenidas en un área de decoración de la cueva de Tito Bustillo (Asturias, así como las actividades en áreas de estancia relacionadas con la preparación y ejecución del arte parietal.
Moeller, Christiane; Benedictus, Marije R.; Koedam, Esther L.G.M.; Scheltens, Philip; Flier, Wiesje M. van der; Versteeg, Adriaan; Wattjes, Mike P.; Barkhof, Frederik; Vrenken, Hugo
Validate the four-point visual rating scale for posterior cortical atrophy (PCA) on magnetic resonance images (MRI) through quantitative grey matter (GM) volumetry and voxel-based morphometry (VBM) to justify its use in clinical practice. Two hundred twenty-nine patients with probable Alzheimer's disease and 128 with subjective memory complaints underwent 3T MRI. PCA was rated according to the visual rating scale. GM volumes of six posterior structures and the total posterior region were extracted using IBASPM and compared among PCA groups. To determine which anatomical regions contributed most to the visual scores, we used binary logistic regression. VBM compared local GM density among groups. Patients were categorised according to their PCA scores: PCA-0 (n = 122), PCA-1 (n = 143), PCA-2 (n = 79), and PCA-3 (n = 13). All structures except the posterior cingulate differed significantly among groups. The inferior parietal gyrus volume discriminated the most between rating scale levels. VBM showed that PCA-1 had a lower GM volume than PCA-0 in the parietal region and other brain regions, whereas between PCA-1 and PCA-2/3 GM atrophy was mostly restricted to posterior regions. The visual PCA rating scale is quantitatively validated and reliably reflects GM atrophy in parietal regions, making it a valuable tool for the daily radiological assessment of dementia. (orig.)
Moeller, Christiane; Benedictus, Marije R.; Koedam, Esther L.G.M.; Scheltens, Philip [VU University Medical Center, Alzheimer Center and Department of Neurology, Neuroscience Campus Amsterdam, P.O. Box 7057, Amsterdam (Netherlands); Flier, Wiesje M. van der [VU University Medical Center, Alzheimer Center and Department of Neurology, Neuroscience Campus Amsterdam, P.O. Box 7057, Amsterdam (Netherlands); VU University Medical Center, Department of Epidemiology and Biostatistics, Neuroscience Campus Amsterdam, P.O. Box 7057, Amsterdam (Netherlands); Versteeg, Adriaan; Wattjes, Mike P.; Barkhof, Frederik [VU University Medical Center, Department of Radiology and Nuclear Medicine, Neuroscience Campus Amsterdam, P.O. Box 7057, Amsterdam (Netherlands); Vrenken, Hugo [VU University Medical Center, Department of Radiology and Nuclear Medicine, Neuroscience Campus Amsterdam, P.O. Box 7057, Amsterdam (Netherlands); VU University Medical Center, Department of Physics and Medical Technology, Neuroscience Campus Amsterdam, P.O. Box 7057, Amsterdam (Netherlands)
Validate the four-point visual rating scale for posterior cortical atrophy (PCA) on magnetic resonance images (MRI) through quantitative grey matter (GM) volumetry and voxel-based morphometry (VBM) to justify its use in clinical practice. Two hundred twenty-nine patients with probable Alzheimer's disease and 128 with subjective memory complaints underwent 3T MRI. PCA was rated according to the visual rating scale. GM volumes of six posterior structures and the total posterior region were extracted using IBASPM and compared among PCA groups. To determine which anatomical regions contributed most to the visual scores, we used binary logistic regression. VBM compared local GM density among groups. Patients were categorised according to their PCA scores: PCA-0 (n = 122), PCA-1 (n = 143), PCA-2 (n = 79), and PCA-3 (n = 13). All structures except the posterior cingulate differed significantly among groups. The inferior parietal gyrus volume discriminated the most between rating scale levels. VBM showed that PCA-1 had a lower GM volume than PCA-0 in the parietal region and other brain regions, whereas between PCA-1 and PCA-2/3 GM atrophy was mostly restricted to posterior regions. The visual PCA rating scale is quantitatively validated and reliably reflects GM atrophy in parietal regions, making it a valuable tool for the daily radiological assessment of dementia. (orig.)
Ragni, Marco; Franzmeier, Imke; Maier, Simon; Knauff, Markus
The psychology of reasoning is currently transitioning from the study of deductive inferences under certainty to inferences that have degrees of uncertainty in both their premises and conclusions; however, only a few studies have explored the cortical basis of uncertain reasoning. Using transcranial magnetic stimulation (TMS), we show that areas in the right superior parietal lobe (rSPL) are necessary for solving spatial relational reasoning problems under conditions of uncertainty. Twenty-four participants had to decide whether a single presented order of objects agreed with a given set of indeterminate premises that could be interpreted in more than one way. During the presentation of the order, 10-Hz TMS was applied over the rSPL or a sham control site. Right SPL TMS during the inference phase disrupted performance in uncertain relational reasoning. Moreover, we found differences in the error rates between preferred mental models, alternative models, and inconsistent models. Our results suggest that different mechanisms are involved when people reason spatially and evaluate different kinds of uncertain conclusions. Copyright © 2016 Elsevier Inc. All rights reserved.
Wormstone, I Michael; Wang, Lixin; Liu, Christopher S C
Posterior Capsule Opacification (PCO) is the most common complication of cataract surgery. At present the only means of treating cataract is by surgical intervention, and this initially restores high visual quality. Unfortunately, PCO develops in a significant proportion of patients to such an extent that a secondary loss of vision occurs. A modern cataract operation generates a capsular bag, which comprises a proportion of the anterior and the entire posterior capsule. The bag remains in situ, partitions the aqueous and vitreous humours, and in the majority of cases, houses an intraocular lens. The production of a capsular bag following surgery permits a free passage of light along the visual axis through the transparent intraocular lens and thin acellular posterior capsule. However, on the remaining anterior capsule, lens epithelial cells stubbornly reside despite enduring the rigours of surgical trauma. This resilient group of cells then begin to re-colonise the denuded regions of the anterior capsule, encroach onto the intraocular lens surface, occupy regions of the outer anterior capsule and most importantly of all begin to colonise the previously cell-free posterior capsule. Cells continue to divide, begin to cover the posterior capsule and can ultimately encroach on the visual axis resulting in changes to the matrix and cell organization that can give rise to light scatter. This review will describe the biological mechanisms driving PCO progression and discuss the influence of IOL design, surgical techniques and putative drug therapies in regulating the rate and severity of PCO.
Utz, N.; Kinkel, B.; Hedde, J.P.; Bewermeyer, H.
Reversible posterior leukoencephalopathy syndrome (PLS) is characterized by headache, altered mental function, visual disturbances and seizures. Neuroimaging studies suggest a white-matter oedema, predominantly in the posterior parietal-temporal-occipital regions of the brain. We present the case of a 30-year-old woman who had suffered her first attack of acute intermittent porphyria (AIP). Following 1 week of abdominal pain she developed several generalized seizures, and hallucinations, and exhibited a progressive deterioration of the consciousness. T2-weighted images, especially fluid-attenuated inversion recovery (FLAIR) sequences showed bilateral lesions in the posterior frontal, parietal and occipital cortex and subcortical white matter. Following treatment with haematin and a high carbohydrate diet the patient's condition improved. Follow-up magnetic resonance imaging (MRI) revealed complete resolution of the lesions. To our knowledge, this is the first report concerning a completely reversible PLS in AIP. (orig.)
Grecucci, Alessandro; Giorgetta, Cinzia; Bonini, Nicolao; Sanfey, Alan G
Previous studies have reported the effect of emotion regulation (ER) strategies on both individual and social decision-making, however, the effect of regulation on socially driven emotions independent of decisions is still unclear. In the present study, we investigated the neural effects of using reappraisal to both up- and down-regulate socially driven emotions. Participants played the Dictator Game (DG) in the role of recipient while undergoing fMRI, and concurrently applied the strategies of either up-regulation (reappraising the proposer's intentions as more negative), down-regulation (reappraising the proposer's intentions as less negative), as well as a baseline "look" condition. Results showed that regions responding to the implementation of reappraisal (effect of strategy, that is, "regulating regions") were the inferior and middle frontal gyrus, temporo parietal junction and insula bilaterally. Importantly, the middle frontal gyrus activation correlated with the frequency of regulatory strategies in daily life, with the insula activation correlating with the perceived ability to reappraise the emotions elicited by the social situation. Regions regulated by reappraisal (effect of regulation, that is, "regulated regions") were the striatum, the posterior cingulate and the insula, showing increased activation for the up-regulation and reduced activation for down-regulation, both compared to the baseline condition. When analyzing the separate effects of partners' behavior, selfish behavior produced an activation of the insula, not observed when subjects were treated altruistically. Here we show for the first time that interpersonal ER strategies can strongly affect neural responses when experiencing socially driven emotions. Clinical implications of these findings are also discussed to understand how the way we interpret others' intentions may affect the way we emotionally react.
Full Text Available Previous studies have reported the effect of emotion regulation strategies on both individual and social decision making, however the effect of regulation on socially driven emotions independent of decisions is still unclear. In the present study, we investigated the neural effects of using reappraisal to both up- and down-regulate socially driven emotions. Participants played the Dictator Game in the role of recipient while undergoing fMRI, and concurrently applied the strategies of either up-regulation (reappraising the proposer’s intentions as more negative, down-regulation (reappraising the proposer’s intentions as less negative, as well as a baseline ‘look’ condition. Results showed that regions responding to the implementation of reappraisal (effect of strategy, that is, regulating regions were the inferior and middle frontal gyrus, temporo parietal junction and insula bilaterally. Importantly, the middle frontal gyrus activation correlated with the frequency of regulatory strategies in daily life, with the insula activation correlating with the perceived ability to reappraise the emotions elicited by the social situation. Regions regulated by reappraisal (effect of regulation, that is, regulated regions were the striatum, the posterior cingulate and the insula, showing increased activation for the up-regulation and reduced activation for down-regulation, both compared to the baseline condition. When analyzing the separate effects of partners’ behavior, selfish behavior produced an activation of the insula, not observed when subjects were treated altruistically. Here we show for the first time that interpersonal emotion regulation strategies can strongly affect neural responses when experiencing socially driven emotions. Clinical implications of these findings are also discussed to understand how the way we interpret others’ intentions may affect the way we emotionally react.
Grecucci, Alessandro; Giorgetta, Cinzia; Bonini, Nicolao; Sanfey, Alan G.
Previous studies have reported the effect of emotion regulation (ER) strategies on both individual and social decision-making, however, the effect of regulation on socially driven emotions independent of decisions is still unclear. In the present study, we investigated the neural effects of using reappraisal to both up- and down-regulate socially driven emotions. Participants played the Dictator Game (DG) in the role of recipient while undergoing fMRI, and concurrently applied the strategies of either up-regulation (reappraising the proposer's intentions as more negative), down-regulation (reappraising the proposer's intentions as less negative), as well as a baseline “look” condition. Results showed that regions responding to the implementation of reappraisal (effect of strategy, that is, “regulating regions”) were the inferior and middle frontal gyrus, temporo parietal junction and insula bilaterally. Importantly, the middle frontal gyrus activation correlated with the frequency of regulatory strategies in daily life, with the insula activation correlating with the perceived ability to reappraise the emotions elicited by the social situation. Regions regulated by reappraisal (effect of regulation, that is, “regulated regions”) were the striatum, the posterior cingulate and the insula, showing increased activation for the up-regulation and reduced activation for down-regulation, both compared to the baseline condition. When analyzing the separate effects of partners' behavior, selfish behavior produced an activation of the insula, not observed when subjects were treated altruistically. Here we show for the first time that interpersonal ER strategies can strongly affect neural responses when experiencing socially driven emotions. Clinical implications of these findings are also discussed to understand how the way we interpret others' intentions may affect the way we emotionally react. PMID:24027512
Christopoulos, Vassilios N; Bonaiuto, James; Kagan, Igor; Andersen, Richard A
The posterior parietal cortex (PPC) has traditionally been considered important for awareness, spatial perception, and attention. However, recent findings provide evidence that the PPC also encodes information important for making decisions. These findings have initiated a running argument of whether the PPC is critically involved in decision making. To examine this issue, we reversibly inactivated the parietal reach region (PRR), the area of the PPC that is specialized for reaching movements, while two monkeys performed a memory-guided reaching or saccade task. The task included choices between two equally rewarded targets presented simultaneously in opposite visual fields. Free-choice trials were interleaved with instructed trials, in which a single cue presented in the peripheral visual field defined the reach and saccade target unequivocally. We found that PRR inactivation led to a strong reduction of contralesional choices, but only for reaches. On the other hand, saccade choices were not affected by PRR inactivation. Importantly, reaching and saccade movements to single instructed targets remained largely intact. These results cannot be explained as an effector-nonspecific deficit in spatial attention or awareness, since the temporary "lesion" had an impact only on reach choices. Hence, the PPR is a part of a network for reach decisions and not just reach planning. There has been an ongoing debate on whether the posterior parietal cortex (PPC) represents only spatial awareness, perception, and attention or whether it is also involved in decision making for actions. In this study we explore whether the parietal reach region (PRR), the region of the PPC that is specialized for reaches, is involved in the decision process. We inactivated the PRR while two monkeys performed reach and saccade choices between two targets presented simultaneously in both hemifields. We found that inactivation affected only the reach choices, while leaving saccade choices intact
Niggemann, P.; Beyer, H.K.; Frey, H.; Grosskurth, D.; Simons, P.; Kuchta, J.
We present the case of a patient with a spondylolisthesis of L5 on S1 due to spondylolysis at the level L5/S1. The vertebral slip was fixed and no anterior instability was found. Using functional magnetic resonance imaging (MRI) in an upright MRI scanner, posterior instability at the level of the spondylolytic defect of L5 was demonstrated. A structure, probably the hypertrophic ligament flava, arising from the spondylolytic defect was displaced toward the L5 nerve root, and a bilateral contact of the displaced structure with the L5 nerve root was shown in extension of the spine. To our knowledge, this is the first case described of posterior instability in patients with spondylolisthesis. The clinical implications of posterior instability are unknown; however, it is thought that this disorder is common and that it can only be diagnosed using upright MRI
Niggemann, P.; Beyer, H.K.; Frey, H.; Grosskurth, D. (Privatpraxis fuer Upright MRT, Koeln (Germany)); Simons, P.; Kuchta, J. (Media Park Klinik, Koeln (Germany))
We present the case of a patient with a spondylolisthesis of L5 on S1 due to spondylolysis at the level L5/S1. The vertebral slip was fixed and no anterior instability was found. Using functional magnetic resonance imaging (MRI) in an upright MRI scanner, posterior instability at the level of the spondylolytic defect of L5 was demonstrated. A structure, probably the hypertrophic ligament flava, arising from the spondylolytic defect was displaced toward the L5 nerve root, and a bilateral contact of the displaced structure with the L5 nerve root was shown in extension of the spine. To our knowledge, this is the first case described of posterior instability in patients with spondylolisthesis. The clinical implications of posterior instability are unknown; however, it is thought that this disorder is common and that it can only be diagnosed using upright MRI.
Kim, Hyung Sock; Huh, Choon Woong; Kim, Dal Soo; Mok, Jin Ho; Kim, In Soo; Yang, Geun Seok [Myongji St. Mary' s Hospital, Seoul (Korea, Republic of)
Encephaloceles are generally regarded as midline abnormalities. A 50-year-old man presented with a parietal intradiploic encephalocele manifesting as intermittent headache for the past 6 months. Computed tomography (CT) showed bone destruction associated with a left parietal lesion. Magnetic resonance imaging (MRI) demonstrated brain herniation within the intradiploic space. Cerebral angiographic imaging showed a normal cerebral vessel pattern within the herniated brain lesion. In this case, surgical treatment may not be necessary in the absence of concurrent symptoms and neurologic deficit. We report the CT, MRI, and angiographic findings of an extremely rare case of parietal intradiploic encephalocele in adulthood.
Kim, Hyung Sock; Huh, Choon Woong; Kim, Dal Soo; Mok, Jin Ho; Kim, In Soo; Yang, Geun Seok
Encephaloceles are generally regarded as midline abnormalities. A 50-year-old man presented with a parietal intradiploic encephalocele manifesting as intermittent headache for the past 6 months. Computed tomography (CT) showed bone destruction associated with a left parietal lesion. Magnetic resonance imaging (MRI) demonstrated brain herniation within the intradiploic space. Cerebral angiographic imaging showed a normal cerebral vessel pattern within the herniated brain lesion. In this case, surgical treatment may not be necessary in the absence of concurrent symptoms and neurologic deficit. We report the CT, MRI, and angiographic findings of an extremely rare case of parietal intradiploic encephalocele in adulthood
Lou, Hans C; Luber, Bruce; Crupain, Michael
For a coherent and meaningful life, conscious self-representation is mandatory. Such explicit "autonoetic consciousness" is thought to emerge by retrieval of memory of personally experienced events ("episodic memory"). During episodic retrieval, functional imaging studies consistently show....... The medial parietal region may, then, be conceived of as a nodal structure in self-representation, functionally connected to both the right parietal and the medial prefrontal cortices. To determine whether medial parietal cortex in this network is essential for episodic memory retrieval with self...
Zhang, Yuanyuan; George, Jasmine; Li, Yun; Olufade, Rebecca; Zhao, Xueying
As a subfamily of matrix metalloproteinases (MMPs), gelatinases including MMP-2 and MMP-9 play an important role in remodeling and homeostasis of the extracellular matrix. However, conflicting results have been reported regarding their expression level and activity in the diabetic kidney. This study investigated whether and how MMP-9 expression and activity were changed in glomerular epithelial cells upon albumin overload. In situ zymography, immunostaining and Western blot for renal MMP gelatinolytic activity and MMP-9 protein expression were performed in Zucker lean and Zucker diabetic rats. Confocal microscopy revealed a focal increase in gelatinase activity and MMP-9 protein in the glomeruli of diabetic rats. Increased glomerular MMP-9 staining was mainly observed in hyperplastic parietal epithelial cells (PECs) expressing claudin-1 in the diabetic kidneys. Interestingly, increased parietal MMP-9 was often accompanied by decreased staining for podocyte markers (nephrin and podocalyxin) in the sclerotic area of affected glomeruli in diabetic rats. Additionally, urinary excretion of podocyte marker proteins was significantly increased in association with the levels of MMP-9 and albumin in the urine of diabetic animals. To evaluate the direct effect of albumin on expression and activity of MMP-9, primary cultured rat glomerular PECs were incubated with rat serum albumin (0.25 - 1 mg/ml) for 24 - 48 hrs. MMP-9 mRNA levels were significantly increased following albumin treatment. Meanwhile, albumin administration resulted in a dose-dependent increase in MMP-9 protein and activity in culture supernatants of PECs. Moreover, albumin activated p44/42 mitogen-activated protein kinase (MAPK) in PECs. Inhibition of p44/42 MAPK suppressed albumin-induced MMP-9 secretion from glomerular PECs. Taken together, we have demonstrated that an up-regulation of MMP-9 in activated parietal epithelium is associated with a loss of adjacent podocytes in progressive diabetic nephropathy
Steve J. Hodges
Full Text Available The most common cause of lower urinary tract obstruction in male infants is posterior urethral valves. Although the incidence has remained stable, the neonatal mortality for this disorder has improved due to early diagnosis and intensive neonatal care, thanks in part to the widespread use of prenatal ultrasound evaluations. In fact, the most common reason for the diagnosis of posterior urethral valves presently is the evaluation of infants for prenatal hydronephrosis. Since these children are often diagnosed early, the urethral obstruction can be alleviated rapidly through catheter insertion and eventual surgery, and their metabolic derangements can be normalized without delay, avoiding preventable infant mortality. Of the children that survive, however, early diagnosis has not had much effect on their long-term prognosis, as 30% still develop renal insufficiency before adolescence. A better understanding of the exact cause of the congenital obstruction of the male posterior urethra, prevention of postnatal bladder and renal injury, and the development of safe methods to treat urethral obstruction prenatally (and thereby avoiding the bladder and renal damage due to obstructive uropathy are the goals for the care of children with posterior urethral valves.
Kronbichler, Lisa; Tschernegg, Melanie; Martin, Anna Isabel; Schurz, Matthias; Kronbichler, Martin
Social cognition abilities are severely impaired in schizophrenia (SZ). The current meta-analysis used foci of 21 individual studies on functional abnormalities in the schizophrenic brain in order to identify regions that reveal convergent under- or over-activation during theory of mind (TOM) tasks. Studies were included in the analyses when contrasting tasks that require the processing of mental states with tasks which did not. Only studies that investigated patients with an ICD or DSM diagnosis were included. Quantitative voxel-based meta-analyses were done using Seed-based d Mapping software. Common TOM regions like medial-prefrontal cortex and temporo-parietal junction revealed abnormal activation in schizophrenic patients: Under-activation was identified in the medial prefrontal cortex, left orbito-frontal cortex, and in a small section of the left posterior temporo-parietal junction. Remarkably, robust over-activation was identified in a more dorsal, bilateral section of the temporo-parietal junction. Further abnormal activation was identified in medial occipito-parietal cortex, right premotor areas, left cingulate gyrus, and lingual gyrus. The findings of this study suggest that SZ patients simultaneously show over- and under-activation in TOM-related regions. Especially interesting, temporo-parietal junction reveals diverging activation patterns with an under-activating left posterior and an over-activating bilateral dorsal section. In conclusion, SZ patients show less specialized brain activation in regions linked to TOM and increased activation in attention-related networks suggesting compensatory effects. © The Author 2017. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center.
Full Text Available BACKGROUND: Monogenic dementias represent a great opportunity to trace disease progression from preclinical to symptomatic stages. Frontotemporal Dementia related to Granulin (GRN mutations presents a specific framework of brain damage, involving fronto-temporal regions and long inter-hemispheric white matter bundles. Multimodal resting-state functional MRI (rs-fMRI is a promising tool to carefully describe disease signature from the earliest disease phase. OBJECTIVE: To define local connectivity alterations in GRN related pathology moving from the presymptomatic (asymptomatic GRN mutation carriers to the clinical phase of the disease (GRN- related Frontotemporal Dementia. METHODS: Thirty-one GRN Thr272fs mutation carriers (14 patients with Frontotemporal Dementia and 17 asymptomatic carriers and 38 healthy controls were recruited. Local connectivity measures (Regional Homogeneity (ReHo, Fractional Amplitude of Low Frequency Fluctuation (fALFF and Degree Centrality (DC were computed, considering age and gender as nuisance variables as well as the influence of voxel-level gray matter atrophy. RESULTS: Asymptomatic GRN carriers had selective reduced ReHo in the left parietal region and increased ReHo in frontal regions compared to healthy controls. Considering Frontotemporal Dementia patients, all measures (ReHo, fALFF and DC were reduced in inferior parietal, frontal lobes and posterior cingulate cortex. Considering GRN mutation carriers, an inverse correlation with age in the posterior cingulate cortex, inferior parietal lobule and orbitofrontal cortex was found. CONCLUSIONS: GRN pathology is characterized by functional brain network alterations even decades before the clinical onset; they involve the parietal region primarily and then spread to the anterior regions of the brain, supporting the concept of molecular nexopathies.
Full Text Available The existence of a network of brain regions which are activated when one undertakes a difficult visual search task is well established. Two primary nodes on this network are right posterior parietal cortex (rPPC and right frontal eye fields. Both have been shown to be involved in the orientation of attention, but the contingency that the activity of one of these areas has on the other is less clear. We sought to investigate this question by using transcranial direct current stimulation (tDCS to selectively decrease activity in rPPC and then asking participants to perform a visual search task whilst undergoing functional magnetic resonance imaging. Comparison with a condition in which sham tDCS was applied revealed that cathodal tDCS over rPPC causes a selective bilateral decrease in frontal activity when performing a visual search task. This result demonstrates for the first time that premotor regions within the frontal lobe and rPPC are not only necessary to carry out a visual search task, but that they work together to bring about normal function.
Aslam, E.; Imran, M.; Faridi, N.M.
Sarcomas usually metastasize to lugs. The following case report describes an unusual metastasis of Ewing's sarcoma to extradural parietal region bilaterally. The primary was found at lower end of ulna. (author)
Full Text Available Face-labeling refers to the ability to classify faces into social categories. This plays a critical role in human interaction as it serves to define concepts of socially acceptable interpersonal behavior. The purpose of the current study was to characterize, what, if any, impairments in face-labeling are detectable in participants with early-stage clinically diagnosed dementia of the Alzheimer type (CDDAT through the use of the sex determination test (SDT. In the current study, four (1 female, 3 males CDDAT and nine (4 females, 5 males age-matched neurotypicals (NT completed the SDT using chimeric faces while undergoing BOLD fMRI. It was expected that CDDAT participants would have poor verbal fluency, which would correspond to poor performance on the SDT. This could be explained by decreased activation and connectivity patterns within the fusiform face area (FFA and anterior cingulate cortex (ACC. DTI was also performed to test the association of pathological deterioration of connectivity in the uncinate fasciculus (UF and verbally-mediated performance. CDDAT showed lower verbal fluency test (VFT performance, but VFT was not significantly correlated to SDT and no significant difference was seen between CDDAT and NT for SDT performance as half of the CDDAT performed substantially worse than NT while the other half performed similarly. BOLD fMRI of SDT displayed differences in the left superior frontal gyrus and posterior cingulate cortex (PCC, but not the FFA or ACC. Furthermore, although DTI showed deterioration of the right inferior and superior longitudinal fasciculi, as well as the PCC, it did not demonstrate significant deterioration of UF tracts. Taken together, early-stage CDDAT may represent a common emerging point for the loss of face labeling ability.
Rajmohan, Ravi; Anderson, Ronald C; Fang, Dan; Meyer, Austin G; Laengvejkal, Pavis; Julayanont, Parunyou; Hannabas, Greg; Linton, Kitten; Culberson, John; Khan, Hafiz; De Toledo, John; Reddy, P Hemachandra; O'Boyle, Michael W
Face-labeling refers to the ability to classify faces into social categories. This plays a critical role in human interaction as it serves to define concepts of socially acceptable interpersonal behavior. The purpose of the current study was to characterize, what, if any, impairments in face-labeling are detectable in participants with early-stage clinically diagnosed dementia of the Alzheimer type (CDDAT) through the use of the sex determination test (SDT). In the current study, four (1 female, 3 males) CDDAT and nine (4 females, 5 males) age-matched neurotypicals (NT) completed the SDT using chimeric faces while undergoing BOLD fMRI. It was expected that CDDAT participants would have poor verbal fluency, which would correspond to poor performance on the SDT. This could be explained by decreased activation and connectivity patterns within the fusiform face area (FFA) and anterior cingulate cortex (ACC). DTI was also performed to test the association of pathological deterioration of connectivity in the uncinate fasciculus (UF) and verbally-mediated performance. CDDAT showed lower verbal fluency test (VFT) performance, but VFT was not significantly correlated to SDT and no significant difference was seen between CDDAT and NT for SDT performance as half of the CDDAT performed substantially worse than NT while the other half performed similarly. BOLD fMRI of SDT displayed differences in the left superior frontal gyrus and posterior cingulate cortex (PCC), but not the FFA or ACC. Furthermore, although DTI showed deterioration of the right inferior and superior longitudinal fasciculi, as well as the PCC, it did not demonstrate significant deterioration of UF tracts. Taken together, early-stage CDDAT may represent a common emerging point for the loss of face labeling ability.
Pehere, Niranjan; Jalali, Subhadra; Deshmukh, Himanshu; Kannabiran, Chitra
Posterior Microphthalmos Pigmentary Retinopathy Syndrome (PMPRS). Posterior microphthalmos (PM) is a relatively infrequent type of microphthalmos where posterior segment is predominantly affected with normal anterior segment measurements. Herein, we report two siblings with posterior microphthalmos retinopathy syndrome with postulated autosomal recessive mode of inheritance. A 13-year-old child had PM and retinitis pigmentosa (RP) and his 7-year-old sister had PM, RP, and foveoschisis. The genetics of this syndrome and variable phenotype is discussed. Importance of being aware of posterior microphthalmos and its posterior segment associations is highlighted.
Esterman, Michael; Verstynen, Timothy; Robertson, Lynn C.
A number of neuroimaging and neuropsychology studies have implicated various regions of parietal cortex as playing a critical role in the binding of color and form into conjunctions. The current study investigates the role of two such regions by examining how parietal transcranial magnetic stimulation (TMS) influences binding errors known as ‘illusory conjunctions.’ Participants made fewer binding errors after 1 Hz rTMS of the right intraparietal sulcus (IPS), while basic perception of featur...
Phillips, Steven; Takeda, Yuji; Singh, Archana
The capacity to integrate multiple sources of information is a prerequisite for complex cognitive ability, such as finding a target uniquely identifiable by the conjunction of two or more features. Recent studies identified greater frontal-parietal synchrony during conjunctive than non-conjunctive (feature) search. Whether this difference also reflects greater information integration, rather than just differences in cognitive strategy (e.g., top-down versus bottom-up control of attention), or task difficulty is uncertain. Here, we examine the first possibility by parametrically varying the number of integrated sources from one to three and measuring phase-locking values (PLV) of frontal-parietal EEG electrode signals, as indicators of synchrony. Linear regressions, under hierarchical false-discovery rate control, indicated significant positive slopes for number of sources on PLV in the 30-38 Hz, 175-250 ms post-stimulus frequency-time band for pairs in the sagittal plane (i.e., F3-P3, Fz-Pz, F4-P4), after equating conditions for behavioural performance (to exclude effects due to task difficulty). No such effects were observed for pairs in the transverse plane (i.e., F3-F4, C3-C4, P3-P4). These results provide support for the idea that anterior-posterior phase-locking in the lower gamma-band mediates integration of visual information. They also provide a potential window into cognitive development, seen as developing the capacity to integrate more sources of information.
Sicking, Eva-Maria; Fuss, Astrid; Uhlig, Sandra; Jirak, Peggy; Dijkman, Henry; Wetzels, Jack; Engel, Daniel R.; Urzynicok, Torsten; Heidenreich, Stefan; Kriz, Wilhelm; Kurts, Christian; Ostendorf, Tammo; Floege, Jürgen; Smeets, Bart
Parietal epithelial cells (PECs) of the renal glomerulus contribute to the formation of both cellular crescents in rapidly progressive GN and sclerotic lesions in FSGS. Subtotal transgenic ablation of podocytes induces FSGS but the effect of specific ablation of PECs is unknown. Here, we established an inducible transgenic mouse to allow subtotal ablation of PECs. Proteinuria developed during doxycycline-induced cellular ablation but fully reversed 26 days after termination of doxycycline administration. The ablation of PECs was focal, with only 30% of glomeruli exhibiting histologic changes; however, the number of PECs was reduced up to 90% within affected glomeruli. Ultrastructural analysis revealed disruption of PEC plasma membranes with cytoplasm shedding into Bowman’s space. Podocytes showed focal foot process effacement, which was the most likely cause for transient proteinuria. After >9 days of cellular ablation, the remaining PECs formed cellular extensions to cover the denuded Bowman’s capsule and expressed the activation marker CD44 de novo. The induced proliferation of PECs persisted throughout the observation period, resulting in the formation of typical cellular crescents with periglomerular infiltrate, albeit without accompanying proteinuria. In summary, subtotal ablation of PECs leads the remaining PECs to react with cellular activation and proliferation, which ultimately forms cellular crescents. PMID:22282596
Ryu, Ji-Ho; Kim, Pil-Jong; Kim, Hong-Gee; Koo, Yong-Seo; Shin, Teo Jeon
Although functional connectivity has received considerable attention in the study of consciousness, few studies have investigated functional connectivity limited to the sedated state where consciousness is maintained but impaired. The aim of the present study was to investigate changes in functional connectivity of the parietal-frontal network resulting from nitrous oxide-induced sedation, and to determine the neural correlates of cognitive impairment during consciousness transition states. Electroencephalography was acquired from healthy adult patients who underwent nitrous oxide inhalation to induce cognitive impairment, and was analyzed using Granger causality (GC). Periods of awake, sedation and recovery for GC between frontal and parietal areas in the delta, theta, alpha, beta, gamma and total frequency bands were obtained. The Friedman test with post-hoc analysis was conducted for GC values of each period for comparison. As a sedated state was induced by nitrous oxide inhalation, power in the low frequency band showed increased activity in frontal regions that was reversed with discontinuation of nitrous oxide. Feedback and feedforward connections analyzed in spectral GC were changed differently in accordance with EEG frequency bands in the sedated state by nitrous oxide administration. Calculated spectral GC of the theta, alpha, and beta frequency regions in the parietal-to-frontal direction was significantly decreased in the sedated state while spectral GC in the reverse direction did not show significant change. Frontal-parietal functional connectivity is significantly affected by nitrous oxide inhalation. Significantly decreased parietal-to-frontal interaction may induce a sedated state. Copyright © 2017 Elsevier B.V. All rights reserved.
Okoh, Alexis Kofi; Yigitbas, Hakan; Berber, Eren
Since its initial description by Mercan et al. laparoscopic posterior retroperitoneal (PR) adrenalectomy has served as an alternaltive to the transabdominal (TL) approach for the treatment of adrenal pathologies. Robotic adrenal surgery has been reported to improve surgeon ergonomics and facilitate dissection. In patients with bilateral adrenal masses, PR adrenalectomy may be the approach of choice. We herein describe the technique, discuss its limitations and present a critical review of the current literature. © 2015 Wiley Periodicals, Inc.
Full Text Available The aim of this study was the analysis of the effect of a learned increase in the dissociation between the rostral anterior cingulate cortex (rACC and the left posterior insula (pInsL on pain intensity and unpleasantness and the contribution of each region to the effect, exploring the possibility to influence the perception of pain with neurofeedback methods. We trained ten healthy subjects to increase the difference in the blood oxygenation level-dependent response between the rACC and pInsL to painful electric stimuli. Subjects learned to increase the dissociation with either the rACC (state 1 or the pInsL (state 2 being higher. For feedback we subtracted the signal of one region from the other and provided feedback in four conditions with six trials each yielding two different states: (rACC – pInsL increase (state 1, rACC – pInsL decrease (state 2, pInsL – rACC increase (state 2, pInsL – rACC decrease (state 1. Significant changes in the dissociation from trial one to six were seen in all conditions. There were significant changes from trial one to six in the pInsL in three of the four conditions, the rACC showed no significant change. Pain intensity or unpleasantness ratings were unrelated to the dissociation between the regions and the activation in each region. Learning success in the conditions did not significantly correlate and there was no significant correlation between the two respective conditions of one state, i.e. learning to achieve a specific state is not a stable ability. The pInsL seems to be the driving force behind changes in the learned dissociation between the regions. Despite successful differential modulation of activation in areas responsive to the painful stimulus, no corresponding changes in the perception of pain intensity or unpleasantness emerged. Learning to induce different states of dissociation between the areas is not a stable ability since success did not correlate overall or between two conditions of
Friedland, T.F.; Budinger, T.F.; Jaqust, W.J.; Yano, Y.; Huesman, R.H.; Knittel, B.; Koss, E.; Ober, B.A.
The anatomical and chemical features of Alzheimer's disease (AD) are not distributed evenly throughout the brain. However, the nature of this focality has not been well established in vivo. Dynamic studies using the Donner 280-Crystal Positron Tomograph with (F-18)2-fluorodeoxyglucose were performed in 17 subjects meeting current research criteria for AD, and in 7 healthy age-matched control subjects. Glucose metabolic rates in the temporal-parietal cortex are 27% lower in AD than in controls. Ratios of activity density reveal consistently lower metabolic rates in temporal-parietal than frontal cortex in the AD group, while healthy aged subjects have equal metabolic rates in the two areas. Similar findings have been reported by other laboratories. A major finding is a striking lateral asymmetry of cortical metabolism in AD which does not favor either hemisphere. (The asymmetry is 13% in the AD group, 3% in controls, p<.005.) This has not been previously reported in AD. The consistency with which anterior-posterior metabolic differences are found in AD suggests that the focality of the metabolic changes may be used to develop a noninvasive diagnostic test for the disorder. The metabolic asymmetry in AD may be compared to the clinical and pathological asymmetry found in Creutzfeldt-Jakob disease, and may represent an additional link between AD and the subacute spongiform encephalopathies.
Schendan, Haline E; Stern, Chantal E
Objects seen from unusual relative to more canonical views require more time to categorize and recognize, and, according to object model verification theories, additionally recruit prefrontal processes for cognitive control that interact with parietal processes for mental rotation. To test this using functional magnetic resonance imaging, people categorized and recognized known objects from unusual and canonical views. Canonical views activated some components of a default network more on categorization than recognition. Activation to unusual views showed that both ventral and dorsal visual pathways, and prefrontal cortex, have key roles in visual object constancy. Unusual views activated object-sensitive and mental rotation (and not saccade) regions in ventrocaudal intraparietal, transverse occipital, and inferotemporal sulci, and ventral premotor cortex for verification processes of model testing on any task. A collateral-lingual sulci "place" area activated for mental rotation, working memory, and unusual views on correct recognition and categorization trials to accomplish detailed spatial matching. Ventrolateral prefrontal cortex and object-sensitive lateral occipital sulcus activated for mental rotation and unusual views on categorization more than recognition, supporting verification processes of model prediction. This visual knowledge framework integrates vision and memory theories to explain how distinct prefrontal-posterior networks enable meaningful interactions with objects in diverse situations.
Kupferberg, Aleksandra; Iacoboni, Marco; Flanagin, Virginia; Huber, Markus; Kasparbauer, Anna; Baumgartner, Thomas; Hasler, Gregor; Schmidt, Florian; Borst, Christoph; Glasauer, Stefan
With advances in technology, artificial agents such as humanoid robots will soon become a part of our daily lives. For safe and intuitive collaboration, it is important to understand the goals behind their motor actions. In humans, this process is mediated by changes in activity in fronto-parietal brain areas. The extent to which these areas are activated when observing artificial agents indicates the naturalness and easiness of interaction. Previous studies indicated that fronto-parietal activity does not depend on whether the agent is human or artificial. However, it is unknown whether this activity is modulated by observing grasping (self-related action) and pointing actions (other-related action) performed by an artificial agent depending on the action goal. Therefore, we designed an experiment in which subjects observed human and artificial agents perform pointing and grasping actions aimed at two different object categories suggesting different goals. We found a signal increase in the bilateral inferior parietal lobule and the premotor cortex when tool versus food items were pointed to or grasped by both agents, probably reflecting the association of hand actions with the functional use of tools. Our results show that goal attribution engages the fronto-parietal network not only for observing a human but also a robotic agent for both self-related and social actions. The debriefing after the experiment has shown that actions of human-like artificial agents can be perceived as being goal-directed. Therefore, humans will be able to interact with service robots intuitively in various domains such as education, healthcare, public service, and entertainment. © 2017 Wiley Periodicals, Inc.
Al Hussain, Turki; Al Mana, Hadeel; Hussein, Maged H; Akhtar, Mohammed
The glomerulus has 3 resident cells namely mesangial cells that produce the mesangial matrix, endothelial cells that line the glomerular capillaries, and podocytes that cover the outer surface of the glomerular basement membrane. Parietal epithelial cells (PrECs), which line the Bowman's capsule are not part of the glomerular tuft but may have an important role in the normal function of the glomerulus. A significant progress has been made in recent years regarding our understanding of the role and function of these cells in normal kidney and in kidneys with various types of glomerulopathy. In crescentic glomerulonephritis necrotizing injury of the glomerular tuft results in activation and leakage of fibrinogen which provides the trigger for excessive proliferation of PrECs giving rise to glomerular crescents. In cases of collapsing glomerulopathy, podocyte injury causes collapse of the glomerular capillaries and activation and proliferation of PrECs, which accumulate within the urinary space in the form of pseudocrescents. Many of the noninflammatory glomerular lesions such as focal segmental glomerulosclerosis and global glomerulosclerosis also result from podocyte injury which causes variable loss of podocytes. In these cases podocyte injury leads to activation of PrECs that extend on to the glomerular tuft where they cause segmental and/or global sclerosis by producing excess matrix, resulting in obliteration of the capillary lumina. In diabetic nephropathy, in addition to increased matrix production in the mesangium and glomerular basement membranes, increased loss of podocytes is an important determinant of long-term prognosis. Contrary to prior belief there is no convincing evidence for an active podocyte proliferation in any of the above mentioned glomerulopathies.
Shulman, Gordon L.; Pope, Daniel L. W.; Astafiev, Serguei V.; McAvoy, Mark P.; Snyder, Abraham Z.; Corbetta, Maurizio
Spatial selective attention is widely considered to be right hemisphere dominant. Previous functional magnetic resonance imaging (fMRI) studies, however, have reported bilateral blood-oxygenation-level-dependent (BOLD) responses in dorsal fronto-parietal regions during anticipatory shifts of attention to a location (Kastner et al., 1999; Corbetta et al., 2000; Hopfinger et al., 2000). Right-lateralized activity has mainly been reported in ventral fronto-parietal regions for shifts of attention to an unattended target stimulus (Arrington et al., 2000; Corbetta et al., 2000). However, clear conclusions cannot be drawn from these studies because hemispheric asymmetries were not assessed using direct voxel-wise comparisons of activity in left and right hemispheres. Here, we used this technique to measure hemispheric asymmetries during shifts of spatial attention evoked by a peripheral cue stimulus and during target detection at the cued location. Stimulus-driven shifts of spatial attention in both visual fields evoked right-hemisphere dominant activity in temporo-parietal junction (TPJ). Target detection at the attended location produced a more widespread right hemisphere dominance in frontal, parietal, and temporal cortex, including the TPJ region asymmetrically activated during shifts of spatial attention. However, hemispheric asymmetries were not observed during either shifts of attention or target detection in the dorsal fronto-parietal regions (anterior precuneus, medial intraparietal sulcus, frontal eye fields) that showed the most robust activations for shifts of attention. Therefore, right hemisphere dominance during stimulus-driven shifts of spatial attention and target detection reflects asymmetries in cortical regions that are largely distinct from the dorsal fronto-parietal network involved in the control of selective attention. PMID:20219998
Full Text Available Pelvic fracture urethral injuries are typically partial and more often complete disruptions of the most proximal bulbar and distal membranous urethra. Emergency management includes suprapubic tube placement. Subsequent primary realignment to place a urethral catheter remains a controversial topic, but what is not controversial is that when there is the development of a stricture (which is usually obliterative with a distraction defect after suprapubic tube placement or urethral catheter removal, the standard of care is delayed urethral reconstruction with excision and primary anastomosis. This paper reviews the management of patients who suffer pelvic fracture urethral injuries and the techniques of preoperative urethral imaging and subsequent posterior urethroplasty.
Gelman, Joel; Wisenbaugh, Eric S.
Pelvic fracture urethral injuries are typically partial and more often complete disruptions of the most proximal bulbar and distal membranous urethra. Emergency management includes suprapubic tube placement. Subsequent primary realignment to place a urethral catheter remains a controversial topic, but what is not controversial is that when there is the development of a stricture (which is usually obliterative with a distraction defect) after suprapubic tube placement or urethral catheter removal, the standard of care is delayed urethral reconstruction with excision and primary anastomosis. This paper reviews the management of patients who suffer pelvic fracture urethral injuries and the techniques of preoperative urethral imaging and subsequent posterior urethroplasty. PMID:26691883
Nelissen, Natalie; Stokes, Mark; Nobre, Anna C; Rushworth, Matthew F S
Using multivoxel pattern analysis (MVPA), we studied how distributed visual representations in human occipitotemporal cortex are modulated by attention and link their modulation to concurrent activity in frontal and parietal cortex. We detected similar occipitotemporal patterns during a simple visuoperceptual task and an attention-to-working-memory task in which one or two stimuli were cued before being presented among other pictures. Pattern strength varied from highest to lowest when the stimulus was the exclusive focus of attention, a conjoint focus, and when it was potentially distracting. Although qualitatively similar effects were seen inside regions relatively specialized for the stimulus category and outside, the former were quantitatively stronger. By regressing occipitotemporal pattern strength against activity elsewhere in the brain, we identified frontal and parietal areas exerting top-down control over, or reading information out from, distributed patterns in occipitotemporal cortex. Their interactions with patterns inside regions relatively specialized for that stimulus category were higher than those with patterns outside those regions and varied in strength as a function of the attentional condition. One area, the frontal operculum, was distinguished by selectively interacting with occipitotemporal patterns only when they were the focus of attention. There was no evidence that any frontal or parietal area actively inhibited occipitotemporal representations even when they should be ignored and were suppressed. Using MVPA to decode information within these frontal and parietal areas showed that they contained information about attentional context and/or readout information from occipitotemporal cortex to guide behavior but that frontal regions lacked information about category identity.
Stokes, Mark; Nobre, Anna C.; Rushworth, Matthew F. S.
Using multivoxel pattern analysis (MVPA), we studied how distributed visual representations in human occipitotemporal cortex are modulated by attention and link their modulation to concurrent activity in frontal and parietal cortex. We detected similar occipitotemporal patterns during a simple visuoperceptual task and an attention-to-working-memory task in which one or two stimuli were cued before being presented among other pictures. Pattern strength varied from highest to lowest when the stimulus was the exclusive focus of attention, a conjoint focus, and when it was potentially distracting. Although qualitatively similar effects were seen inside regions relatively specialized for the stimulus category and outside, the former were quantitatively stronger. By regressing occipitotemporal pattern strength against activity elsewhere in the brain, we identified frontal and parietal areas exerting top-down control over, or reading information out from, distributed patterns in occipitotemporal cortex. Their interactions with patterns inside regions relatively specialized for that stimulus category were higher than those with patterns outside those regions and varied in strength as a function of the attentional condition. One area, the frontal operculum, was distinguished by selectively interacting with occipitotemporal patterns only when they were the focus of attention. There was no evidence that any frontal or parietal area actively inhibited occipitotemporal representations even when they should be ignored and were suppressed. Using MVPA to decode information within these frontal and parietal areas showed that they contained information about attentional context and/or readout information from occipitotemporal cortex to guide behavior but that frontal regions lacked information about category identity. PMID:24133250
Thomas, Monzy; George, Nysia I; Saini, Upasana T; Patterson, Tucker A; Hanig, Joseph P; Bowyer, John F
Amphetamine (AMPH) is used to treat attention deficit and hyperactivity disorders, but it can produce neurotoxicity and adverse vascular effects at high doses. The endoplasmic reticulum (ER) stress response (ERSR) entails the unfolded protein response, which helps to avoid or minimize ER dysfunction. ERSR is often associated with toxicities resulting from the accumulation of unfolded or misfolded proteins and has been associated with methamphetamine toxicity in the striatum. The present study evaluates the effect of AMPH on several ERSR elements in meninges and associated vasculature (MAV), parietal cortex, and striatum. Adult, male Sprague-Dawley rats were exposed to saline, environmentally induced hyperthermia (EIH) or four consecutive doses of AMPH that produce hyperthermia. Expression changes (mRNA and protein levels) of key ERSR-related genes in MAV, striatum, and parietal cortex at 3 h or 1 day postdosing were monitored. AMPH increased the expression of some ERSR-related genes in all tissues. Atf4 (activating transcription factor 4, an indicator of Perk pathway activation), Hspa5/Grp78 (Glucose regulated protein 78, master regulator of ERSR), Pdia4 (protein disulfide isomerase, protein-folding enzyme), and Nfkb1 (nuclear factor of kappa b, ERSR sensor) mRNA increased significantly in MAV and parietal cortex 3 h after AMPH. In striatum, Atf4 and Hspa5/Grp78 mRNA significantly increased 3 h after AMPH, but Pdia4 and Nfkb11 did not. Thus, AMPH caused a robust activation of the Perk pathway in all tissues, but significant Ire1 pathway activation occurred only after AMPH treatment in the parietal cortex and striatum. Ddit3/Chop, a downstream effector of the ERSR pathway related to the neurotoxicity, was only increased in striatum and parietal cortex. Conversely, Pdia4, an enzyme protective in the ERSR, was only increased in MAV. The overall ERSR manifestation varied significantly between MAV, striatum, and parietal cortex after a neurotoxic exposure to AMPH.
Christoph A. Becker
Full Text Available The cingulate cortex and insula are among the neural structures whose activations have been modulated in functional imaging studies examining discrete states of thirst and drinking to satiation. Building upon these findings, the present study aimed to identify neural structures that change their pattern of activation elicited by water held in the mouth in relation to the internal body state, i.e., proportional to continuous water consumption. Accordingly, participants in a thirsty state were scanned while receiving increments of water until satiety was reached. As expected, fluid ingestion led to a clear decrease in self-reported thirst and the pleasantness ratings of the water ingested. Furthermore, linear decreases in the blood oxygenation level dependent (BOLD response to water ingestion were observed in the anterior mid-cingulate cortex (aMCC and right posterior insula as participants shifted towards the non-thirsty state. In addition, regions in the superior temporal gyrus (STG, supplementary motor area (SMA, superior parietal lobule (SPL, precuneus and calcarine sulcus also showed a linear decrease with increasing fluid consumption. Further analyses related single trial BOLD responses of associated regions to trial-by-trial ratings of thirst and pleasantness. Overall, the aMCC and posterior insula may be key sites of a neural network representing the motivation for drinking based on the dynamic integration of internal state and external stimuli.
Chiao, Joan Y; Harada, Tokiko; Oby, Emily R; Li, Zhang; Parrish, Todd; Bridge, Donna J
Mental representations of social status hierarchy share properties with that of numbers. Previous neuroimaging studies have shown that the neural representation of numerical magnitude lies within a network of regions within inferior parietal cortex. However the neural basis of social status hierarchy remains unknown. Using fMRI, we studied subjects while they compared social status magnitude of people, objects and symbols, as well as numerical magnitude. Both social status and number comparisons recruited bilateral intraparietal sulci. We also observed a semantic distance effect whereby neural activity within bilateral intraparietal sulci increased for semantically close relative to far numerical and social status comparisons. These results demonstrate that social status and number comparisons recruit distinct and overlapping neuronal representations within human inferior parietal cortex.
Yamazaki, Yumiko; Yokochi, Hiroko; Tanaka, Michio; Okanoya, Kazuo; Iriki, Atsushi
The anterior portion of the inferior parietal cortex possesses comprehensive representations of actions embedded in behavioural contexts. Mirror neurons, which respond to both self-executed and observed actions, exist in this brain region in addition to those originally found in the premotor cortex. We found that parietal mirror neurons responded differentially to identical actions embedded in different contexts. Another type of parietal mirror neuron represents an inverse and complementary property of responding equally to dissimilar actions made by itself and others for an identical purpose. Here, we propose a hypothesis that these sets of inferior parietal neurons constitute a neural basis for encoding the semantic equivalence of various actions across different agents and contexts. The neurons have mirror neuron properties, and they encoded generalization of agents, differentiation of outcomes, and categorization of actions that led to common functions. By integrating the activities of these mirror neurons with various codings, we further suggest that in the ancestral primates' brains, these various representations of meaningful action led to the gradual establishment of equivalence relations among the different types of actions, by sharing common action semantics. Such differential codings of the components of actions might represent precursors to the parts of protolanguage, such as gestural communication, which are shared among various members of a society. Finally, we suggest that the inferior parietal cortex serves as an interface between this action semantics system and other higher semantic systems, through common structures of action representation that mimic language syntax.
Catani, Marco; Robertsson, Naianna; Beyh, Ahmad
projections were reconstructed for both species and results compared to identify similarities or differences in tract anatomy (i.e., trajectories and cortical projections). In addition, post-mortem dissections were performed in a human brain. The largest tract identified in both human and monkey brains...... and angular gyri of the inferior parietal lobule in humans but only to the supramarginal gyrus in the monkey brain. The third tract connects the postcentral gyrus to the anterior region of the superior parietal lobule and is more prominent in monkeys compared to humans. Finally, short U-shaped fibres...... and monkeys with some differences for those areas that have cytoarchitectonically distinct features in humans. The overall pattern of intraparietal connectivity supports the special role of the inferior parietal lobule in cognitive functions characteristic of humans....
Michael T Lippert
Full Text Available Perception greatly benefits from integrating multiple sensory cues into a unified percept. To study the neural mechanisms of sensory integration, model systems are required that allow the simultaneous assessment of activity and the use of techniques to affect individual neural processes in behaving animals. While rodents qualify for these requirements, little is known about multisensory integration and areas involved for this purpose in the rodent. Using optical imaging combined with laminar electrophysiological recordings, the rat parietal cortex was identified as an area where visual and somatosensory inputs converge and interact. Our results reveal similar response patterns to visual and somatosensory stimuli at the level of current source density (CSD responses and multi-unit responses within a strip in parietal cortex. Surprisingly, a selective asymmetry was observed in multisensory interactions: when the somatosensory response preceded the visual response, supra-linear summation of CSD was observed, but the reverse stimulus order resulted in sub-linear effects in the CSD. This asymmetry was not present in multi-unit activity however, which showed consistently sub-linear interactions. These interactions were restricted to a specific temporal window, and pharmacological tests revealed significant local intra-cortical contributions to this phenomenon. Our results highlight the rodent parietal cortex as a system to model the neural underpinnings of multisensory processing in behaving animals and at the cellular level.
Kim, Ra Gyung; Cho, Jongwook; Ree, Jinkyue; Kim, Hyung-Sun; Rosa-Neto, Pedro; Kim, Jin-Myung; Lee, Min-Cheol; Kim, Hyoung-Ihl
The prevalence of subcortical white matter strokes in elderly patients is on the rise, but these patients show mixed responses to conventional rehabilitative interventions. To examine whether cortical electrical stimulation can promote motor recovery after white matter stroke, we delivered stimulation to a small or wide region of sensory-parietal cortex for two weeks in a rodent model of circumscribed subcortical capsular infarct. The sham-operated group (SOG) showed persistent and severe motor impairments together with decreased activation in bilateral sensorimotor cortices and striatum. In contrast, sensory-parietal cortex stimulation significantly improved motor recovery: final recovery levels were 72.9% of prelesion levels in the wide stimulation group (WSG) and 37% of prelesion levels in the small stimulation group (SSG). The microPET imaging showed reversal of cortical diaschisis in both groups: in both hemispheres for the WSG, and in the hemisphere ipsilateral to stimulation in the SSG. In addition, we observed activation of the corpus callosum and subcortical corticostriatal structures after stimulation. The results from the c-Fos mapping study were grossly consistent with the microPET imaging. Sensory-parietal cortex stimulation may therefore be a useful strategy for overcoming the limits of rehabilitative training in patients with severe forms of subcortical capsular infarct. © The Author(s) 2015.
Luna-Antonio, Brenda I; Rodriguez-Muñoz, Rafael; Namorado-Tonix, Carmen; Vergara, Paula; Segovia, Jose; Reyes, Jose L
Gas1 (Growth Arrest-Specific 1) is a pleiotropic protein with novel functions including anti-proliferative and proapoptotic activities. In the kidney, the expression of Gas1 has been described in mesangial cells. In this study, we described that renal parietal cells of Bowman's capsule (BC) and the distal nephron cells also express Gas1. The role of Gas1 in the kidney is not yet known. There is a subpopulation of progenitor cells in Bowman's capsule with self-renewal properties which can eventually differentiate into podocytes as a possible mechanism of regeneration in the early stages of diabetic nephropathy. We analyzed the expression of Gas1 in the parietal cells of Bowman's capsule in murine experimental diabetes. We found that diabetes reduced the expression of Gas1 and increased the expression of progenitor markers like NCAM, CD24, and SIX1/2, and mesenchymal markers like PAX2 in the Bowman's capsule. We also analyzed the expression of WT1 (a podocyte-specific marker) on BC and observed an increase in the number of WT1 positive cells in diabetes. In contrast, nephrin, another podocyte-specific protein, decreases its expression in the first week of diabetes in the glomerular tuft, which is gradually restored during the second and third weeks of diabetes. These results suggest that in diabetes the decrease of Gas1 promotes the activation of parietal progenitor cells of Bowman's capsule that might differentiate into podocytes and compensate their loss observed in this pathology.
Correani, Alessia; Humphreys, Glyn W
The attentional blink, a measure of the temporal dynamics of visual processing, has been documented to be more pronounced following brain lesions that are associated with visual neglect. This suggests that, in addition to their spatial bias in attention, neglect patients may have a prolonged dwell time for attention. Here the attentional dwell time was examined in patients with damage focused on either posterior parietal or frontal cortices. In three experiments, we show that there is an abnormally pronounced attentional dwell time, which does not differ in patients with posterior parietal and with frontal lobe lesions, and this is associated with a measure of selective attention but not with measures of spatial bias in selection. These data occurred both when we attempted to match patients and controls for overall differences in performance and when a single set stimulus exposure was used across participants. In Experiments 1 and 2, requiring report of colour-form conjunctions, there was evidence that the patients were also impaired at temporal binding, showing errors in feature combination across stimuli and in reporting in the correct temporal order. In Experiment 3, requiring only the report of features but introducing task switching led to similar results. The data suggest that damage to a frontoparietal network can compromise temporal selection of visual stimuli; however, this is not necessarily related to a deficit in hemispatial visual attention but it is to impaired target selection. We discuss the implications for understanding visual selection.
Park, Jong Oag; Woo, Je Ho; Ki, Tae Sung; Lee, Jong Hwa; Chung, Jin Woo; Lee, Don Young
It has been known that there are several areas of T2 hyperintensity in normal white matter of brain, such as terminal zones of myelination, ependymitis granularis, ones of posterior internal capsule, and perivascular space. The aim of our study is to demonstrate another region of T2 hyperintensities in normal pediatric age group. We have studied brain MR for 10 normal volunteers and 35 patients without having intracranial lesions in pediatric age group(3-19 years). In 5 among 45 cases, focal T2 hyperintensities were seen in the parietal periventricular white matter beneath the postcentral gyri. They were noted as poorly defined, 5-10 mm sized areas of increased signal intensities on T2-weighted axial images. They were also characterized by bilateral, posteromedially oriented, short band-like or oval areas. Interestingly, they were directly continuous with the T2 hyperintensity of posterior internal capsule. In spite of the relatively highly frequency in the pediatric population as in our study, this finding has not been reported in the asymptomatic adults. The results show that the bilateral anterior parietal hyperintense areas may be another terminal zones of delayed myelination affecting the parietopontine tract. They should be differentiated from pathologic T2 hyperintensities by their characteristic findings
Weishaupt, D.; Zanetti, M.; Hodler, J.; Nyffeler, R.W.; Gerber, C.
Objective. To assess the shape of the posterior glenoid rim in patients with recurrent (atraumatic) posterior instability.Design and patients. CT examinations of 15 shoulders with recurrent (atraumatic) posterior instability were reviewed in masked fashion with regard to abnormalities of the glenoid shape, specifically of its posterior rim. The glenoid version was also assessed. The findings were compared with the findings in 15 shoulders with recurrent anterior shoulder instability and 15 shoulders without instability. For all patients, surgical correlation was available.Results. Fourteen of the 15 (93%) shoulders with recurrent (atraumatic) posterior shoulder instability had a deficiency of the posteroinferior glenoid rim. In patients with recurrent anterior instability or stable shoulders such deficiencies were less common (60% and 73%, respectively). The craniocaudal length of the deficiencies was largest in patients with posterior instability. When a posteroinferior deficiency with a craniocaudal length of 12 mm or more was defined as abnormal, sensitivity and specificity for diagnosing recurrent (atraumatic) posterior instability were 86.7% and 83.3%, respectively. There was a statistically significant difference in glenoid version between shoulders with posterior instability and stable shoulders (P=0.01).Conclusion. Recurrent (atraumatic) posterior shoulder instability should be considered in patients with a bony deficiency of the posteroinferior glenoid rim with a craniocaudal length of more than 12 mm. (orig.)
Different activation of opercular and posterior cingulate cortex (PCC) in patients with complex regional pain syndrome (CRPS I) compared with healthy controls during perception of electrically induced pain: a functional MRI study.
Freund, Wolfgang; Wunderlich, Arthur P; Stuber, Gregor; Mayer, Florian; Steffen, Peter; Mentzel, Martin; Weber, Frank; Schmitz, Bernd
Although the etiology of complex regional pain syndrome type 1 (CRPS 1) is still debated, many arguments favor central maladaptive changes in pain processing as an important causative factor. To look for the suspected alterations, 10 patients with CRPS affecting the left hand were explored with functional magnetic resonance imaging during graded electrical painful stimulation of both hands subsequently and compared with healthy participants. Activation of the anterior insula, posterior cingulate cortex (PCC), and caudate nucleus was seen in patients during painful stimulation. Compared with controls, CRPS patients had stronger activation of the PCC during painful stimulation of the symptomatic hand. The comparison of insular/opercular activation between controls and patients with CRPS I during painful stimulation showed stronger (posterior) opercular activation in controls than in patients. Stronger PCC activation during painful stimulation may be interpreted as a correlate of motor inhibition during painful stimuli different from controls. Also, the decreased opercular activation in CRPS patients shows less sensory-discriminative processing of painful stimuli.These results show that changed cerebral pain processing in CRPS patients is less sensory-discriminative but more motor inhibition during painful stimuli. These changes are not limited to the diseased side but show generalized alterations of cerebral pain processing in chronic pain patients.
Full Text Available A 62-year-old female patient with metastatic renal cell carcinoma under third-line treatment with pazopanib for 8 weeks suddenly developed severe headaches, grand mal seizures and paresis of the left arm in combination with gait instability as well as nausea and vomiting during her vacation abroad. The emergency physician measured systolic blood pressure values over 300 mm Hg and suspected a stroke. The CT imaging without contrast agent in a local hospital did not show any pathologic findings despite bone metastases. The colleagues suspected cerebral metastases or meningeosis carcinomatosa and referred the patient to our department for further diagnostics and treatment planning. An MRI scan ruled out the suspected cerebral metastases or meningeosis carcinomatosa, but showed signs of reversible posterior leukoencephalopathy syndrome (RPLS in the form of band-like hyperintensities as a sign of cytotoxic edema in the gray and white matter of the left parietal lobe. The patient then reported that similar blood pressure values had been measured shortly after the start of a first-line therapy with sunitinib, so that we discontinued the current treatment with pazopanib. Within 6 days the neurologic symptoms vanished and the patient was discharged. An intermittent hypertension persisted. A follow-up MRI 3 weeks later showed an RPLS-typical cortical infarction in the affected area. RPLS should be considered as the actual reason for neurologic findings in hypertensive patients with known metastatic cancers under tyrosine kinase inhibitor therapy.
Full Text Available History of present illness: A 22-year-old male presented to the Emergency Department complaining of right shoulder pain after a motocross accident. He was traveling at approximately 10 mph around a turn when he lost control and was thrown over the handlebars, landing directly on his right shoulder. On arrival, he was holding his arm in adduction and internal rotation. An area of swelling was noted over his anterior shoulder. He was unable to abduct his shoulder. No humeral gapping was noted. He had normal neuro-vascular status distal to the injury. Significant findings: Radiographs demonstrated posterior displacement of the humeral head on the “Y” view (see white arrow and widening of the glenohumeral joint space on anterior-posterior view (see red arrow. The findings were consistent with posterior dislocation and a Hill-Sachs type deformity. Sedation was performed and reduction was attempted using external rotation, traction counter-traction. An immediate “pop” was felt during the procedure. Post-procedure radiographs revealed a persistent posterior subluxation with interlocking at posterior glenoid. CT revealed posterior dislocation with acute depressed impaction deformity medial to the biceps groove with the humeral head perched on the posterior glenoid, interlocked at reverse Hill-Sachs deformity (see blue arrow. Discussion: Posterior shoulder dislocations are rare and represent only 2% of all shoulder dislocations. Posterior shoulder dislocations are missed on initial diagnosis in more than 60% of cases.1 Posterior shoulder dislocations result from axial loading of the adducted and internally rotated shoulder, violent muscle contractions (resulting from seizures or electrocution, a direct posterior force applied to the anterior shoulder.1 Physical findings include decreased anterior prominence of the humeral head, increased palpable posterior prominence of the humeral head below the acromion, increased palpable prominence of the
Agostino, Paola; Ugolini, Alessandro; Signori, Alessio; Silvestrini-Biavati, Armando; Harrison, Jayne E; Riley, Philip
included 15 studies, of which two were at low risk of bias, seven were at high risk of bias and six were unclear. Fixed appliances with mid-palatal expansionNine studies tested fixed appliances with mid-palatal expansion against each other. No study reported a difference between any type of appliance. Fixed versus removable appliancesFixed quad-helix appliances may be 20% more likely to correct crossbites than removable expansion plates (RR 1.20; 95% CI 1.04 to 1.37; two studies; 96 participants; low-quality evidence).Quad-helix appliances may achieve 1.15 mm more molar expansion than expansion plates (MD 1.15 mm; 95% CI 0.40 to 1.90; two studies; 96 participants; moderate-quality evidence).There was insufficient evidence of a difference in canine expansion or the stability of crossbite correction.Very limited evidence showed that both fixed quad-helix appliances and removable expansion plates were superior to composite onlays in terms of crossbite correction, molar and canine expansion. Other comparisonsVery limited evidence showed that treatments were superior to no treatment, but there was insufficient evidence of a difference between any active treatments. There is a very small body of low- to moderate-quality evidence to suggest that the quad-helix appliance may be more successful than removable expansion plates at correcting posterior crossbites and expanding the inter-molar width for children in the early mixed dentition (aged eight to 10 years). The remaining evidence we found was of very low quality and was insufficient to allow the conclusion that any one intervention is better than another for any of the outcomes in this review.
Full Text Available Xuming Liu,1 Zhihan Yan,2 Tingyu Wang,1 Xiaokai Yang,1 Feng Feng,3 Luping Fan,1 Jian Jiang4 1Department of Radiology, The Third Clinical Institute Affiliated to Wenzhou Medical University, Wenzhou, 2Department of Radiology, The 2nd Affiliated Hospital of Wenzhou Medical University, Wenzhou, 3Peking Union Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, 4Department of Radiology, The First Affiliated Hospital of Nanchang University, Nanchang, People’s Republic of China Objective: The aim of this study was to use functional magnetic resonance imaging (fMRI technique to explore the resting-state functional connectivity (rsFC differences of the bilaterial cerebellum posterior lobe (CPL after normal sleep (NS and after sleep deprivation (SD. Methods: A total of 16 healthy subjects (eight males, eight females underwent an fMRI scan twice at random: once following NS and the other following 24 hours’ SD, with an interval of 1 month between the two scans. The fMRI scanning included resting state and acupuncture stimulation. The special activated regions located during the acupuncture stimulation were selected as regions of interest for rsFC analysis. Results: Bilateral CPLs were positively activated by acupuncture stimulation. In the NS group, the left CPL showed rsFC with the bilateral CPL, bilateral frontal lobe (BFL, left precuneus and right inferior parietal lobule, while the right CPL showed rsFC with the bilateral temporal lobe, right cerebellum anterior lobe, right CPL, left frontal lobe, left anterior cingulate, right posterior cingulate, and bilateral inferior parietal lobule. In the SD group, the left CPL showed rsFC with the left posterior cingulate gyrus bilateral CPL, left precuneus, left precentral gyrus, BFL, and the left parietal lobe, while the right CPL showed rsFC with bilateral cerebellum anterior lobe, bilateral CPL, left frontal lobe and left temporal lobe. Compared with the NS group, the
Paul, J.; Kanotra, Sohit Paul; Kanotra, Sonika
The traditional method of management of posterior epistaxis has been with anteroposterior nasal packing. Apart from the high failure rate of 26–50% reported in various series, nasal packing is associated with marked discomfort and several complications. In order to avoid nasal packing, we started doing endoscopic cauterization in cases of posterior epistaxis. A total of 23 patients with posterior epistaxis were subjected to nasal endoscopy with the intent to stop bleeding by cauterization of ...
Galeano Weber, Elena M; Hahn, Tim; Hilger, Kirsten; Fiebach, Christian J
Limitations in visual working memory (WM) quality (i.e., WM precision) may depend on perceptual and attentional limitations during stimulus encoding, thereby affecting WM capacity. WM encoding relies on the interaction between sensory processing systems and fronto-parietal 'control' regions, and differences in the quality of this interaction are a plausible source of individual differences in WM capacity. Accordingly, we hypothesized that the coupling between perceptual and attentional systems affects the quality of WM encoding. We combined fMRI connectivity analysis with behavioral modeling by fitting a variable precision and fixed capacity model to the performance data obtained while participants performed a visual delayed continuous response WM task. We quantified functional connectivity during WM encoding between occipital and parietal brain regions activated during both perception and WM encoding, as determined using a conjunction of two independent experiments. The multivariate pattern of voxel-wise inter-areal functional connectivity significantly predicted WM performance, most specifically the mean of WM precision but not the individual number of items that could be stored in memory. In particular, higher occipito-parietal connectivity was associated with higher behavioral mean precision. These results are consistent with a network perspective of WM capacity, suggesting that the efficiency of information flow between perceptual and attentional neural systems is a critical determinant of limitations in WM quality. Copyright © 2016 Elsevier Inc. All rights reserved.
Bolognini, Nadia; Miniussi, Carlo
Transcranial magnetic stimulation (TMS) and transcranial electric stimulation (tES) are noninvasive brain stimulation (NIBS) tools that are now widely used in neuroscientific research in humans. The fact that both TMS and tES are able to modulate brain plasticity and, in turn, affect behavior is opening up new horizons in the treatment of brain circuit and plasticity disorders. In the present chapter, we will first provide the reader with a brief background on the basic principles of NIBS, describing the electromagnetic and physical foundations of TMS and tES, as well as the current knowledge of the neurophysiologic basis of their effects on brain activity and plasticity. In the main part, we will outline studies aimed at improving persistent symptoms and deficits in patients suffering from neurologic and neuropsychiatric disorders featured by dysfunction of the parietal lobe. The emerging view is that NIBS of parietal areas holds the promise to overcome various sensory, motor, and cognitive disorders that are often refractory to standard medical or behavioral therapies. The chapter closes with an outlook on further developments in this realm, discussing novel therapeutic approaches that could lead to more effective rehabilitation procedures, better suited for the specific parietal lobe dysfunction. Copyright © 2018 Elsevier B.V. All rights reserved.
Molnar-Szakacs, Istvan; Kaplan, Jonas; Greenfield, Patricia M; Iacoboni, Marco
A fronto-parietal mirror neuron network in the human brain supports the ability to represent and understand observed actions allowing us to successfully interact with others and our environment. Using functional magnetic resonance imaging (fMRI), we wanted to investigate the response of this network in adults during observation of hierarchically organized action sequences of varying complexity that emerge at different developmental stages. We hypothesized that fronto-parietal systems may play a role in coding the hierarchical structure of object-directed actions. The observation of all action sequences recruited a common bilateral network including the fronto-parietal mirror neuron system and occipito-temporal visual motion areas. Activity in mirror neuron areas varied according to the motoric complexity of the observed actions, but not according to the developmental sequence of action structures, possibly due to the fact that our subjects were all adults. These results suggest that the mirror neuron system provides a fairly accurate simulation process of observed actions, mimicking internally the level of motoric complexity. We also discuss the results in terms of the links between mirror neurons, language development and evolution.
Lee, Sang Kwon; Kim, Yong Sun [Kyungpook National Univ. Taegu (Korea, Republic of); Kwon, Soon Hak [Ulsan Univ. College of Medicine, Seoul (Korea, Republic of)
To find out the characteristic MR findings of reversible posterior leukoen-cephalopathy syndrome (RPLS) due to various causes in chldren. Eigh children with RPLS underwent MR imaging, and the findings were retrospectively analyzed. All eight were acutely hypertensive at the time of a neurotoxic episode. Three had intra-abdominal tumors (one adrenal pheochromo-cytoma, one para-aortic paraganglioma and one para-aortic ganglioneuroma encasing the left renal artery): three were being treated with cyclosporine: one was being treated with steroid: and one had hemolytric uremic syndrome. Initial cranial MR images were analyzed with particular emphasis on the distribution of the lesions. To assess possible sequelae, follow-up MR images were obtained in seven patients at least one week after the treatment of hypertension. Four underwent proton MR spectroscopy. Characteristic distribution of lesions in the occipital and posterior parietal lobes was identified in all cases regardless of the causes of RPLS. The cerebellum, basal ganglia, anterior parietal, and frontal lobe were involved in four, two, one, and one case, respectively. Cortical gray matter involvement was predominant in six and subcortical white matter involvement predominated in two patients. The distribution of lesions was bilateral and asymmetric. Gyriform enhancement was identified in six cases, and small hemorrhage was noted in one. In seven patients, the clinical and MR findings improved without sequelae on follow-up study. In one, proton MR spectroscopy demonstrated a high lactate peak at the time of the neurologic event. Nearnormal spectra were noted in three children who underwent proton MR spectroscopy after recovery. The MR findings of RPLS are characteristic in that lesions are distributed in the posterior region of the brain and they are reversible on follow-up study. In children with RPLS due to unknown causes, the possibility of intra-abdominal tumors should also be consiodered.
Lee, Sang Kwon; Kim, Yong Sun; Kwon, Soon Hak
To find out the characteristic MR findings of reversible posterior leukoen-cephalopathy syndrome (RPLS) due to various causes in chldren. Eigh children with RPLS underwent MR imaging, and the findings were retrospectively analyzed. All eight were acutely hypertensive at the time of a neurotoxic episode. Three had intra-abdominal tumors (one adrenal pheochromo-cytoma, one para-aortic paraganglioma and one para-aortic ganglioneuroma encasing the left renal artery): three were being treated with cyclosporine: one was being treated with steroid: and one had hemolytric uremic syndrome. Initial cranial MR images were analyzed with particular emphasis on the distribution of the lesions. To assess possible sequelae, follow-up MR images were obtained in seven patients at least one week after the treatment of hypertension. Four underwent proton MR spectroscopy. Characteristic distribution of lesions in the occipital and posterior parietal lobes was identified in all cases regardless of the causes of RPLS. The cerebellum, basal ganglia, anterior parietal, and frontal lobe were involved in four, two, one, and one case, respectively. Cortical gray matter involvement was predominant in six and subcortical white matter involvement predominated in two patients. The distribution of lesions was bilateral and asymmetric. Gyriform enhancement was identified in six cases, and small hemorrhage was noted in one. In seven patients, the clinical and MR findings improved without sequelae on follow-up study. In one, proton MR spectroscopy demonstrated a high lactate peak at the time of the neurologic event. Nearnormal spectra were noted in three children who underwent proton MR spectroscopy after recovery. The MR findings of RPLS are characteristic in that lesions are distributed in the posterior region of the brain and they are reversible on follow-up study. In children with RPLS due to unknown causes, the possibility of intra-abdominal tumors should also be consiodered
Full Text Available Arithmetic skill is of critical importance for academic achievement, professional success and everyday life, and childhood is the key period to acquire this skill. Neuroimaging studies have identified that left parietal regions are a key neural substrate for representing arithmetic skill. Although the relationship between functional brain activity in left parietal regions and arithmetic skill has been studied in detail, it remains unclear about the relationship between arithmetic achievement and structural properties in left inferior parietal area in schoolchildren. The current study employed a combination of voxel-based morphometry (VBM for high-resolution T1-weighted images and fiber tracking on diffusion tensor imaging (DTI to examine the relationship between structural properties in the inferior parietal area and arithmetic achievement in 10-year-old schoolchildren. VBM of the T1-weighted images revealed that individual differences in arithmetic scores were significantly and positively correlated with the grey matter (GM volume in the left intraparietal sulcus (IPS. Fiber tracking analysis revealed that the forceps major, left superior longitudinal fasciculus (SLF, bilateral inferior longitudinal fasciculus (ILF and inferior fronto-occipital fasciculus (IFOF were the primary pathways connecting the left IPS with other brain areas. Furthermore, the regression analysis of the probabilistic pathways revealed a significant and positive correlation between the fractional anisotropy (FA values in the left SLF, ILF and bilateral IFOF and arithmetic scores. The brain structure-behavior correlation analyses indicated that the GM volumes in the left IPS and the FA values in the tract pathways connecting left IPS were both related to children’s arithmetic achievement. The present findings provide evidence that individual structural differences in the left IPS are associated with arithmetic scores in schoolchildren.
Full Text Available As a subfamily of matrix metalloproteinases (MMPs, gelatinases including MMP-2 and MMP-9 play an important role in remodeling and homeostasis of the extracellular matrix. However, conflicting results have been reported regarding their expression level and activity in the diabetic kidney. This study investigated whether and how MMP-9 expression and activity were changed in glomerular epithelial cells upon albumin overload. In situ zymography, immunostaining and Western blot for renal MMP gelatinolytic activity and MMP-9 protein expression were performed in Zucker lean and Zucker diabetic rats. Confocal microscopy revealed a focal increase in gelatinase activity and MMP-9 protein in the glomeruli of diabetic rats. Increased glomerular MMP-9 staining was mainly observed in hyperplastic parietal epithelial cells (PECs expressing claudin-1 in the diabetic kidneys. Interestingly, increased parietal MMP-9 was often accompanied by decreased staining for podocyte markers (nephrin and podocalyxin in the sclerotic area of affected glomeruli in diabetic rats. Additionally, urinary excretion of podocyte marker proteins was significantly increased in association with the levels of MMP-9 and albumin in the urine of diabetic animals. To evaluate the direct effect of albumin on expression and activity of MMP-9, primary cultured rat glomerular PECs were incubated with rat serum albumin (0.25 - 1 mg/ml for 24 - 48 hrs. MMP-9 mRNA levels were significantly increased following albumin treatment. Meanwhile, albumin administration resulted in a dose-dependent increase in MMP-9 protein and activity in culture supernatants of PECs. Moreover, albumin activated p44/42 mitogen-activated protein kinase (MAPK in PECs. Inhibition of p44/42 MAPK suppressed albumin-induced MMP-9 secretion from glomerular PECs. Taken together, we have demonstrated that an up-regulation of MMP-9 in activated parietal epithelium is associated with a loss of adjacent podocytes in progressive
These results indicate the presence of the homogalacturonans and rhamnogalacturonans in pectin. This study constitutes the preliminary data obtained in the biochemical analysis of the parietal compounds of the roots of a species which grows in an arid area in comparison with those of its aerial parts. Keywords: Retama ...
The diagnostic value of the isotope scintigraphy of the brain in the parieal projection with the change of the dip angle of the gamma-chamber detector to the plane of the physiological horizontal was revealed. The observation was made on 100 patients with suspected presence of the volumetric process of the brain. Three variants of placing were studied: the parietal projection - standard (collimator plane parallel to the plane of physiological horizontal and strictly perpendicular to the sagittal plane); the placing with an angle of 30 deg between the detector plane and the physiological horizontal, opened at the front (posterio-parietal); placing with an angle of 30 deg between the detector plane and the physiological horizontal opened at the back (anterio-parietal). A comparative analysis of scintigrams with focal processes of the brain showed the largest informativeness of the proposed modification of the parietal projection in the form of a change of the dip angle of the gamma-chamber detector plane to the plane of the physiological horizontal opened at the back; this makes it possible to reveal more thoroughly the focus of the increased, pathological accumulation of the isotope in different parts of the skull, where the use of as standard placing is of small informativeness
Sicking, E.M.; Fuss, A.; Uhlig, S.; Jirak, P.; Dijkman, H.; Wetzels, J.; Engel, D.R.; Urzynicok, T.; Heidenreich, S.; Kriz, W.; Kurts, C.; Ostendorf, T.; Floege, J.; Smeets, B.; Moeller, M.J.
Parietal epithelial cells (PECs) of the renal glomerulus contribute to the formation of both cellular crescents in rapidly progressive GN and sclerotic lesions in FSGS. Subtotal transgenic ablation of podocytes induces FSGS but the effect of specific ablation of PECs is unknown. Here, we established
Smeets, B.; Moeller, M.J.
In recent years, it has become apparent that parietal epithelial cells (PECs) play an important role within the renal glomerulus, in particular in diseased conditions. In this review, we examine current knowledge about the role of PECs and their interactions with podocytes in development and under
Miesen, L.; Steenbergen, E.; Smeets, B.
In normal glomeruli, parietal epithelial cells (PECs) line the inside of Bowman's capsule and form an inconspicuous sheet of flat epithelial cells in continuity with the proximal tubular epithelial cells (PTECs) at the urinary pole and with the podocytes at the vascular pole. PECs, PTECs and
Parietal epithelial cells of Bowman's capsules were first described by Sir William Bowman in 1842 in his paper On the Structure and Use of the Malpighian Bodies of the Kidney [London, Taylor, 1842], but since then their functions have remained poorly understood. A large body of evidence has recently suggested that parietal epithelial cells represent a reservoir of renal progenitors in adult human kidney which generate novel podocytes during childhood and adolescence, and can regenerate injured podocytes. The discovery that parietal epithelial cells represent a potential source for podocyte regeneration suggests that podocyte injury can be repaired. However, recent results also suggest that an abnormal proliferative response of renal progenitors to podocyte injury can generate hyperplastic glomerular lesions that are observed in crescentic glomerulonephritis and other types of glomerular disorders. Taken together, these results establish an entirely novel view that changes the way of thinking about renal physiology and pathophysiology, and suggest that understanding how self-renewal and fate decision of parietal epithelial cells in response to podocyte injury may be perturbed or modulated will be crucial for obtaining novel tools for prevention and treatment of glomerulosclerosis. Copyright © 2011 S. Karger AG, Basel.
Berger, K.; Schulte, K.; Boor, P.; Kuppe, C.; Kuppevelt, T.H. van; Floege, J.; Smeets, B.; Moeller, M.J.
Previously, we showed that some podocytes in juvenile mice are recruited from cells lining Bowman's capsule, suggesting that parietal epithelial cells (PECs) are a progenitor cell population for podocytes. To investigate whether PECs also replenish podocytes in adult mice, PECs were genetically
Full Text Available Modafinil is employed for the treatment of narcolepsy and has also been, off-label, used to treat cognitive dysfunction in neuropsychiatric disorders. In a previous study, we have reported that single dose administration of modafinil in healthy young subjects enhances fluid reasoning and affects resting state activity in the Fronto Parietal Control (FPC and Dorsal Attention (DAN networks. No changes were found in the Salience Network (SN, a surprising result as the network is involved in the modulation of emotional and fluid reasoning. The insula is crucial hub of the SN and functionally divided in anterior and posterior subregions.Using a seed-based approach, we have now analyzed effects of modafinil on the functional connectivity (FC of insular subregions.Analysis of FC with resting state fMRI (rs-FMRI revealed increased FC between the right posterior insula and the putamen, the superior frontal gyrus and the anterior cingulate cortex in the modafinil-treated group.Modafinil is considered a putative cognitive enhancer. The rs-fMRI modifications that we have found are consistent with the drug cognitive enhancing properties and indicate subregional targets of action.ClinicalTrials.gov NCT01684306.
signal intensity located in the bilateral frontal lobes, parietal lobes, temporal lobes and occipital lobes. (arrows); B and C, T2WI and FLAIR sequence, respectively, both of which show hyperintense signals in the same positions indicated by arrows; D, DWI shows slightly increased signals in the frontal lobes and isointense ...
de Vries, Ingmar E J; van Driel, Joram; Olivers, Christian N L
Current models of visual search assume that search is guided by an active visual working memory representation of what we are currently looking for. This attentional template for currently relevant stimuli can be dissociated from accessory memory representations that are only needed prospectively, for a future task, and that should be prevented from guiding current attention. However, it remains unclear what electrophysiological mechanisms dissociate currently relevant (serving upcoming selection) from prospectively relevant memories (serving future selection). We measured EEG of 20 human subjects while they performed two consecutive visual search tasks. Before the search tasks, a cue instructed observers which item to look for first (current template) and which second (prospective template). During the delay leading up to the first search display, we found clear suppression of α band (8-14 Hz) activity in regions contralateral to remembered items, comprising both local power and interregional phase synchronization within a posterior parietal network. Importantly, these lateralization effects were stronger when the memory item was currently relevant (i.e., for the first search) compared with when it was prospectively relevant (i.e., for the second search), consistent with current templates being prioritized over future templates. In contrast, event-related potential analysis revealed that the contralateral delay activity was similar for all conditions, suggesting no difference in storage. Together, these findings support the idea that posterior α oscillations represent a state of increased processing or excitability in task-relevant cortical regions, and reflect enhanced cortical prioritization of memory representations that serve as a current selection filter. SIGNIFICANCE STATEMENT Our days are filled with looking for relevant objects while ignoring irrelevant visual information. Such visual search activity is thought to be driven by current goals activated in
Wang, Mengxing; Zhang, Jilei; Dong, Guangheng; Zhang, Hui; Lu, Haifeng; Du, Xiaoxia
Although the mirror neuron system (MNS) has been extensively studied in monkeys and adult humans, very little is known about its development. Previous studies suggest that the MNS is present by infancy and that the brain and MNS-related cognitive abilities (such as language, empathy, and imitation learning) continue to develop after childhood. In humans, the PFt area of the inferior parietal lobule (IPL) seems to particularly correlate with the functional properties of the PF area in primates, which contains mirror neurons. However, little is known about the functional connectivity (FC) of the PFt area with other brain areas and whether these networks change over time. Here, we investigated the FC development of the PFt area-based network in 59 healthy subjects aged 7-26 years at resting-state to study brain development from late childhood through adolescence to early adulthood. The bilateral PFt showed similar core FC networks, which included the frontal lobe, the cingulate gyri, the insula, the somatosensory cortex, the precuneus, the superior and inferior parietal lobules, the temporal lobe, and the cerebellum posterior lobes. Furthermore, the FC between the left PFt and the left IPL exhibited a significantly positive correlation with age, and the FC between the left PFt and the right postcentral gyrus exhibited a significantly negative correlation with age. In addition, the FC between the right PFt and the right putamen exhibited a significantly negative correlation with age. Our findings suggest that the PFt area-based network develops and is reorganized with age. Copyright © 2017 ISDN. Published by Elsevier Ltd. All rights reserved.
Melzer, P; Morgan, V L; Pickens, D R; Price, R R; Wall, R S; Ebner, F F
Functional magnetic resonance imaging was performed on blind adults resting and reading Braille. The strongest activation was found in primary somatic sensory/motor cortex on both cortical hemispheres. Additional foci of activation were situated in the parietal, temporal, and occipital lobes where visual information is processed in sighted persons. The regions were differentiated most in the correlation of their time courses of activation with resting and reading. Differences in magnitude and expanse of activation were substantially less significant. Among the traditionally visual areas, the strength of correlation was greatest in posterior parietal cortex and moderate in occipitotemporal, lateral occipital, and primary visual cortex. It was low in secondary visual cortex as well as in dorsal and ventral inferior temporal cortex and posterior middle temporal cortex. Visual experience increased the strength of correlation in all regions except dorsal inferior temporal and posterior parietal cortex. The greatest statistically significant increase, i.e., approximately 30%, was in ventral inferior temporal and posterior middle temporal cortex. In these regions, words are analyzed semantically, which may be facilitated by visual experience. In contrast, visual experience resulted in a slight, insignificant diminution of the strength of correlation in dorsal inferior temporal cortex where language is analyzed phonetically. These findings affirm that posterior temporal regions are engaged in the processing of written language. Moreover, they suggest that this function is modified by early visual experience. Furthermore, visual experience significantly strengthened the correlation of activation and Braille reading in occipital regions traditionally involved in the processing of visual features and object recognition suggesting a role for visual imagery. Copyright 2001 Wiley-Liss, Inc.
Brotchie, P.; Chen, D.Y.; Bradley, W.G.
Full text: In order for us to interact with our environment we need to know where objects are around us, relative to our body. In monkeys, a body-centred map of visual space is known to exist within the parietal eye fields. This map is formed by the modulation of neuronal activity by eye and head position (Brotchie et al, Nature 1995; Synder et al, Nature 1998). In humans no map of body centred space has been demonstrated. By using functional MRI we have localised a region along the intraparietal sulcus which has properties similar to the parietal eye fields of monkeys (Brotchie et al, ISMRM, 2000). The aim of this study was to determine if activity in this region is modulated by head position, consistent with a body centered representation of visual space. Functional MRI was performed on 6 subjects performing simple visually guided saccades using a 1.5 Tesla GE Echospeed scanner. 10 scans were performed on the 6 subjects at left and right body orientations. Regions of interest were selected around the intraparietal sulcus proper (IPSP) of both hemispheres and voxels with BOLD signal which correlated with the paradigm (r>0.35) were selected for further analysis. Comparisons of percentage signal change were made between the left and right IPSP using Student t test. Of the 10 MRI examinations, 6 demonstrated statistically significant differences in the amount of signal change between left and right IPSP. In each of these 6 cases, the signal change was greater within the IPSP contralateral to the direction of head position relative to the body. This indicates a modulation of activity within the IPSP related to head position, most likely reflecting modulation of the underlying neuronal activity and suggests the existence of a body-centred encoding of space within the parietal eye fields of humans. Copyright (2002) Blackwell Science Pty Ltd
Full Text Available ‘Getting a joke’ always requires resolving an apparent incongruity but the particular cognitive operations called upon vary depending on the nature of the joke itself. Previous research has identified the primary neural correlates of the cognitive and affective processes called upon to respond to humor generally, but little work has been done on the substrates underlying the distinct cognitive operations required to comprehend particular joke types. This study explored the neural correlates of the cognitive processes required to successfully comprehend three joke types: bridging-inference jokes, exaggeration jokes and ambiguity jokes. For all joke types, the left dlPFC appeared to support common cognitive mechanisms, such as script-shifting, while the vACC was associated with affective appreciation. The temporo-parietal lobe (TPJ and MTG was associated with bridging-inference jokes, suggesting involvement of these regions with ‘theory of mind’ processing. The ventral fronto-parietal lobe (IPL and IFG was associated with both exaggeration and ambiguity jokes, suggesting that it supports executive control processes such as retrieval from episodic memory, self-awareness, and language-based decoding. The social-affective appreciation of verbal jokes was associated with activity in the orbitofrontal cortex, amygdala, ventral anterior cingulate cortex (vACC, and parahippocampal gyrus. These results allow a more precise account of the neural
Full Text Available Background Posterior cortical atrophy (PCA is a kind of progressive neurodegenerative disease with cortical visual impairment as the first symptom. Because of rare clinical incidence, early onset age, special clinical symptoms and unobvious MRI abnormality, the definitive diagnosis of PCA is difficult. This study used 18F-fluoro-2-deoxy-D-glucose (18F-FDG PET and 11C-Pittsburgh compound B (11C-PIB PET for PCA patients with unobvious MRI abnormality, so as to discuss the value of PET in the early diagnosis of PCA. Methods Five patients diagnosed as PCA in our hospital between April 2012 and March 2015 were enrolled in this study. Cognitive function was measured by Mini-Mental State Examination (MMSE, Montreal Cognitive Assessment (MoCA, Activities of Daily Living (ADL and Clock Drawing Test (CDT. Brain MRI, 18F-FDG PET and 11C-PIB PET were performed to analyze glucose metabolism and perfusion of posterior cortex. Results Neuropsychological tests revealed that the ability of writing, calculating, visuospatial and executive function of all these patients were impaired. Color vision tests showed abnormal results. MRI showed that the posterior atrophy (PA scores were 0-2 (average 1 on the left side and 0-1 (average 0.80 on the right side. The medial temporal atrophy (MTA scores were 1-3 (average 1.80 on the left side and 1-4 (average 2 on the right side. The ventricular enlargement (VE scores were 1-2 (average 1.80 on the left side and 1-2 (average 1.60 on the right side. 18F-FDG PET showed glucose metabolism decreased obviously on bilateral temporo-parieto-occipital cortex, precuneus and cingulate gyrus, and slightly on frontal lobes and subcortical structure. 11C-PIB PET showed radioactive 11C-PIB deposition on bilateral frontal, temporal, parietal and occipital cortex, and the outline of cerebellar cortex was clear. Conclusions For PCA patients whose parietal and occipital cortical atrophy is not obvious on MRI, 18F-FDG PET
Full Text Available One theory to account for neglect symptoms in patients with right focal damage invokes a release of inhibition of the right parietal cortex over the left parieto-frontal circuits, by disconnection mechanism. This theory is supported by transcranial magnetic stimulation studies showing the existence of asymmetric inhibitory interactions between the left and right posterior parietal cortex, with a right hemispheric advantage. These inhibitory mechanisms are mediated by direct transcallosal projections located in the posterior portions of the corpus callosum. The current study, using diffusion imaging and tract-based spatial statistics (TBSS, aims at assessing, in a data-driven fashion, the contribution of structural disconnection between hemispheres in determining the presence and severity of neglect. Eleven patients with right acute stroke and 11 healthy matched controls underwent MRI at 3T, including diffusion imaging, and T1-weighted volumes. TBSS was modified to account for the presence of the lesion and used to assess the presence and extension of changes in diffusion indices of microscopic white matter integrity in the left hemisphere of patients compared to controls, and to investigate, by correlation analysis, whether this damage might account for the presence and severity of patients' neglect, as assessed by the Behavioural Inattention Test (BIT. None of the patients had any macroscopic abnormality in the left hemisphere; however, 3 cases were discarded due to image artefacts in the MRI data. Conversely, TBSS analysis revealed widespread changes in diffusion indices in most of their left hemisphere tracts, with a predominant involvement of the corpus callosum and its projections on the parietal white matter. A region of association between patients' scores at BIT and brain FA values was found in the posterior part of the corpus callosum. This study strongly supports the hypothesis of a major role of structural disconnection between the
Crane, Andrea K; Myers, Erinn M; Lippmann, Quinn K; Matthews, Catherine A
Knowledge of how to anatomically reconstruct extensive posterior-compartment defects is variable among gynecologists. The objective of this video is to demonstrate an effective technique of overlapping sphincteroplasty and posterior repair. In this video, a scripted storyboard was constructed that outlines the key surgical steps of a comprehensive posterior compartment repair: (1) surgical incision that permits access to posterior compartment and perineal body, (2) dissection of the rectovaginal space up to the level of the cervix, (3) plication of the rectovaginal muscularis, (4) repair of internal and external anal sphincters, and (5) reconstruction of the perineal body. Using a combination of graphic illustrations and live video footage, tips on repair are highlighted. The goals at the end of repair are to: (1) have improved vaginal caliber, (2) increase rectal tone along the entire posterior vaginal wall, (3) have the posterior vaginal wall at a perpendicular plane to the perineal body, (4) reform the hymenal ring, and (5) not have an overly elongated perineal body. This video provides a step-by-step guide on how to perform an overlapping sphincteroplasty and posterior repair.
Marmorale, C; Scibé, R; Siquini, W; Massa, M; Brunelli, A; Landi, E
Laparoscopic cholecystectomy (VALC) represents the treatment of choice for the symptomatic gallstones. However the occurrence of an adenocarcinoma of the gallbladder results a controindication for this surgical technique. We present a case of a 52 years old woman who underwent a VALC; histology revealed a gallbladder adenocarcinoma. For this reason the patient underwent a second operation that is right hepatic trisegmentectomy. Six months later the patient presented with a parietal recurrence at the extraction site of the gallbladder. We discuss the possible mechanism responsible for carcinomatous dissemination during laparoscopic surgery and we raccommend the use of some procedures in order to limit the risk and eventually to treat a neoplastic parietal seeding. These complications suggest the problem about the utility and the future played by video assisted laparoscopic surgery in the diagnosis and treatment of intraabdominal malignancies.
Full Text Available A number of immunocytochemical studies have indicated the presence of cholinergic neurons in the cerebral cortex of various species of mammals. Whether such cholinergic neurons in the human cerebral cortex are exclusively of subcortical origin is still debated. In this immunocytochemical study, the existence of cortical cholinergic neurons was investigated on surgical samples of human parietal association neocortex using a highly specific monoclonal antibody against choline acetyltransferase (ChAT, the acetylcholine biosynthesising enzyme. ChAT immunoreactivity was detected in a subpopulation of neurons located in layers II and III. These were small or medium-sized pyramidal neurons which showed cytoplasmic immunoreactivity in the perikarya and processes, often in close association to blood microvessels. This study, providing demonstration of ChAT neurons in the human parietal neocortex, strongly supports the existence of intrinsic cholinergic innervation of the human neocortex. It is likely that these neurons contribute to the cholinergic innervation of the intracortical microvessels.
Ihori, Nami; Kawamura, Mitsuru; Araki, Shigeo; Kawachi, Juro
To investigate the neuropsychological mechanisms of kinesthetic alexia, we asked 7 patients who showed kinesthetic alexia with preserved visual reading after damage to the left parietal region to perform tasks consisting of kinesthetic written reproduction (writing down the same letter as the kinesthetic stimulus), kinesthetic reading aloud, visual written reproduction (copying letters), and visual reading aloud of hiragana (Japanese phonograms). We compared the performance in these tasks and the lesion sites in each patient. The results suggested that deficits in any one of the following functions might cause kinesthetic alexia: (1) the retrieval of kinesthetic images (motor engrams) of characters from kinesthetic stimuli, (2) kinesthetic images themselves, (3) access to cross-modal association from kinesthetic images, and (4) cross-modal association itself (retrieval of auditory and visual images from kinesthetic images of characters). Each of these factors seemed to be related to different lesion sites in the left parietal lobe. Copyright 2002 S. Karger AG, Basel
Kakehashi, Akihiro; Takezawa, Mikiko; Akiba, Jun
Diagnosing a posterior vitreous detachment (PVD) is important for predicting the prognosis and determining the indication for vitreoretinal surgery in many vitreoretinal diseases. This article presents both classifications of a PVD by slit-lamp biomicroscopy and of a shallow PVD by optical coherence tomography (OCT). By biomicroscopy, the vitreous condition is determined based on the presence or absence of a PVD. The PVD then is classified as either a complete posterior vitreous detachment (C-PVD) or a partial posterior vitreous detachment (P-PVD). A C-PVD is further divided into a C-PVD with collapse and a C-PVD without collapse, while a P-PVD is divided into a P-PVD with shrinkage of the posterior hyaloid membrane (P-PVD with shrinkage) and a P-PVD without shrinkage of the posterior hyaloid membrane (P-PVD without shrinkage). A P-PVD without shrinkage has a subtype characterized by vitreous gel attachment through the premacular hole in a posterior hyaloid membrane to the macula (P-PVD without shrinkage [M]). By OCT, a shallow PVD is classified as the absence of a shallow PVD or as a shallow PVD. A shallow PVD is then subclassified as a shallow PVD without shrinkage of the posterior vitreous cortex, a shallow PVD with shrinkage of the posterior vitreous cortex, and a peripheral shallow PVD. A shallow PVD without shrinkage of the posterior vitreous cortex has two subtypes: an age-related shallow PVD and a perifoveal PVD associated with a macular hole. PMID:24376338
Miesen, Laura; Steenbergen, Eric; Smeets, Bart
In normal glomeruli, parietal epithelial cells (PECs) line the inside of Bowman?s capsule and form an inconspicuous sheet of flat epithelial cells in continuity with the proximal tubular epithelial cells (PTECs) at the urinary pole and with the podocytes at the vascular pole. PECs, PTECs and podocytes have a common mesenchymal origin and are the result of divergent differentiation during embryogenesis. Podocytes and PTECs are highly differentiated cells with well-established functions pertain...
Rozeik, C.; Kotterer, O.; Deininger, H.K.
We report a case of blunt chest trauma, where findings on repeated conventional chest radiographs were compatible with pneumothorax developing after 2 days of mechanical high-pressure ventilation. CT showed that the appearance was due to a detachment of the parietal pleura along the lateral, mediastinal and diaphragmatic boundaries of the lungs, imitating a pneumothorax. The case report illustrates the key role of CT in the differential diagnosis of epipleural interstitial air collection versus pneumothorax. (orig./MG)
Rozeik, C. [Radiologie 1, Staedtische Kliniken Darmstadt (Germany); Kotterer, O. [Radiologie 1, Staedtische Kliniken Darmstadt (Germany); Deininger, H.K. [Radiologie 1, Staedtische Kliniken Darmstadt (Germany)
We report a case of blunt chest trauma, where findings on repeated conventional chest radiographs were compatible with pneumothorax developing after 2 days of mechanical high-pressure ventilation. CT showed that the appearance was due to a detachment of the parietal pleura along the lateral, mediastinal and diaphragmatic boundaries of the lungs, imitating a pneumothorax. The case report illustrates the key role of CT in the differential diagnosis of epipleural interstitial air collection versus pneumothorax. (orig./MG)
Shankland, Stuart J.; Anders, Hans-Joachim; Romagnani, Paola
Purpose of review We have summarized recently published glomerular parietal epithelial cell (PEC) research, focusing on their roles in glomerular development and physiology, and in certain glomerular diseases. The rationale is that PECs have been largely ignored until the recent availability of cell lineage tracing studies, human and murine PEC culture systems, and potential therapeutic interventions of PECs. Recent findings Several new paradigms involving PECs have emerged demonstrating thei...
Berger, Katja; Schulte, Kevin; Boor, Peter; Kuppe, Christoph; van Kuppevelt, Toin H.; Floege, Jürgen; Smeets, Bart; Moeller, Marcus J.
Previously, we showed that some podocytes in juvenile mice are recruited from cells lining Bowman’s capsule, suggesting that parietal epithelial cells (PECs) are a progenitor cell population for podocytes. To investigate whether PECs also replenish podocytes in adult mice, PECs were genetically labeled in an irreversible fashion in 5-week-old mice. No significant increase in labeled podocytes was observed, even after 18 months. To accelerate a potential regenerative mechanism, progressive glo...
Ahmed, M.; Eid, A. F.; Sheikh, M. Y.; Yiannakou, N.
Primary posterior mediastinal hydatid cyst is a serious health problem for the Mediterranean countries. We diagnosed a case of a 46-year-old female with a primary posterior mediastinum hydatid cyst on CT and MRI. It was provisionally identified as either a hydatid cyst or bronchogenic cyst or neuroenteric cyst. CT guided aspiration with 18 gauge needle confirmed as hydatid sand. This is very rare in this population but it should be kept in mind when one is looking at any cyst in the posterior mediastinum. (author)
Svoboda, Jan; Telenský, Petr; Blahna, Karel; Zach, P.; Bureš, Jan; Stuchlík, Aleš
Roč. 445, č. 1 (2008), s. 73-77 ISSN 0304-3940 R&D Projects: GA MŠk(CZ) 1M0517; GA ČR(CZ) GA309/07/0341; GA ČR(CZ) GD206/05/H012 Institutional research plan: CEZ:AV0Z50110509 Keywords : learning * memory * rat Subject RIV: FH - Neurology Impact factor: 2.200, year: 2008
Yuan, Ye; Brown, Steven
Drawing and writing are the two major means of creating what are referred to as "images", namely visual patterns on flat surfaces. They share many sensorimotor processes related to visual guidance of hand movement, resulting in the formation of visual shapes associated with pictures and words. However, while the human capacity to draw is tens of thousands of years old, the capacity for writing is only a few thousand years old, and widespread literacy is quite recent. In order to compare the neural activations for drawing and writing, we conducted two activation likelihood estimation (ALE) meta-analyses for these two bodies of neuroimaging literature. The results showed strong overlap in the activation profiles, especially in motor areas (motor cortex, frontal eye fields, supplementary motor area, cerebellum, putamen) and several parts of the posterior parietal cortex. A distinction was found in the left posterior parietal cortex, with drawing showing a preference for a ventral region and writing a dorsal region. These results demonstrate that drawing and writing employ the same basic sensorimotor networks but that some differences exist in parietal areas involved in spatial processing. Copyright © 2015 Elsevier Inc. All rights reserved.
Yu, Xiaodan; Chen, Chuansheng; Pu, Song; Wu, Chenxing; Li, Yongnian; Jiang, Tao; Zhou, Xinlin
Previous research has consistently shown that the left parietal cortex is critical for numerical processing, but the role of the right parietal lobe has been much less clear. This study used the intraoperative cortical electrical stimulation approach to investigate neural dissociation in the right parietal cortex for subtraction and…
Mollo, Giovanna; Jefferies, Elizabeth; Cornelissen, Piers; Gennari, Silvia P
An MEG study investigated the role of context in semantic interpretation by examining the comprehension of ambiguous words in contexts leading to different interpretations. We compared high-ambiguity words in minimally different contexts (to bowl, the bowl) to low-ambiguity counterparts (the tray, to flog). Whole brain beamforming revealed the engagement of left inferior frontal gyrus (LIFG) and posterior middle temporal gyrus (LPMTG). Points of interest analyses showed that both these sites showed a stronger response to verb-contexts by 200 ms post-stimulus and displayed overlapping ambiguity effects that were sustained from 300 ms onwards. The effect of context was stronger for high-ambiguity words than for low-ambiguity words at several different time points, including within the first 100 ms post-stimulus. Unlike LIFG, LPMTG also showed stronger responses to verb than noun contexts in low-ambiguity trials. We argue that different functional roles previously attributed to LIFG and LPMTG are in fact played out at different periods during processing. Crown Copyright © 2018. Published by Elsevier Inc. All rights reserved.
Wael M. Moussa
Aug 27, 2012 ... of the CNS, representing about a third of brain tumors. They arise from the ... subtypes based on cell structure.1–4 In 1979, the World Health. Organization .... anterior or posterior to the internal auditory meatus), petrocli-.
Kizilirmak, Jasmin M; Rösler, Frank; Bien, Siegfried; Khader, Patrick H
The attention to memory theory (AtoM) proposes that the same brain regions might be involved in selective processing of perceived stimuli (selective attention) and memory representations (selective retrieval). Although this idea is compelling, given consistently found neural overlap between perceiving and remembering stimuli, recent comparisons brought evidence for overlap as well as considerable differences. Here, we present a paradigm that enables the investigation of the AtoM hypothesis from a novel perspective to gain further insight into the neural resources involved in AtoM. Selective attention in perception is often investigated as a control process that shows lingering effects on immediately following trials. Here, we employed a paradigm capable of modulating selective retrieval in a similarly dynamic manner as in such selective-attention paradigms by inducing trial-to-trial shifts between relevant and irrelevant memory representations as well as changes of the width of the internal focus on memory. We found evidence for an involvement of bilateral inferior parietal lobe and right inferior frontal gyrus in reorienting the attentional focus on previously accessed memory representations. Moreover, we could dissociate the right inferior from the parietal activation in separate contrasts, suggesting that the right inferior frontal gyrus plays a role in facilitating attentional reorienting to memory representations when competing representations have been activated in the preceding trial, potentially by resolving this competition. Our results support the AtoM theory, i.e. that ventral frontal and parietal regions are involved in automatic attentional reorienting in memory, and highlight the importance of further investigations of the overlap and differences between regions involved in internal (memory) and external (perceptual) attentional selection. Copyright © 2015 Elsevier B.V. All rights reserved.
Full Text Available Sensitivity to regularities plays a crucial role in the acquisition of various linguistic features from spoken language input. Artificial grammar (AG learning paradigms explore pattern recognition abilities in a set of structured sequences (i.e. of syllables or letters. In the present study, we investigated the functional underpinnings of learning phonological regularities in auditorily presented syllable sequences. While previous neuroimaging studies either focused on functional differences between the processing of correct vs. incorrect sequences or between different levels of sequence complexity, here the focus is on the neural foundation of the actual learning success. During functional magnetic resonance imaging (fMRI, participants were exposed to a set of syllable sequences with an underlying phonological rule system, known to ensure performance differences between participants. We expected that successful learning and rule application would require phonological segmentation and phoneme comparison. As an outcome of four alternating learning and test fMRI sessions, participants split into successful learners and non-learners. Relative to non-learners, successful learners showed increased task-related activity in a fronto-parietal network of brain areas encompassing the left lateral premotor cortex as well as bilateral superior and inferior parietal cortices during both learning and rule application. These areas were previously associated with phonological segmentation, phoneme comparison and verbal working memory. Based on these activity patterns and the phonological strategies for rule acquisition and application, we argue that successful learning and processing of complex phonological rules in our paradigm is mediated via a fronto-parietal network for phonological processes.
Kakehashi, A.; Kado, M.; Akiba, J.; Hirokawa, H.
AIMS—To identify variations in posterior vitreous detachment (PVD) and establish a clinical classification system for PVD. METHODS—400 consecutive eyes were examined using biomicroscopy and vitreous photography and classified the PVD variations—complete PVD with collapse, complete PVD without collapse, partial PVD with thickened posterior vitreous cortex (TPVC), or partial PVD without TPVC. RESULTS—In each PVD type, the most frequently seen ocular pathologies were as follows: in complete PVD ...
Full Text Available Purpose: To investigate the influence of electroencephalograph bionic electrical stimulation on neuronal activity in patients with Alzheimer's disease (AD using resting-state blood oxygen level dependent functional MRI (BOLD-fMRI and amplitude of low-frequency fluctuation (ALFF and fraction ALFF (fALFF analysis. Methods: 42 AD patients were divided into two groups in accordance with the randomized double blind principle, every group was 21. Treatment group received electroencephalograph bionic electrical stimulation. Both groups received resting-state BOLD-fMRI scanning before and after treatment and comparing differences in ALFF and fALFF in each group by statistical methods. Correlation analysis was performed between ALFF or fALFF images and neuropsychological tests scale after treatment. Results: Post-therapy brain regions with higher ALFF included left cerebellum posterior lobe, right cerebellum posterior lobe, left hippocampus/parahippocampus, left posterior cingulated cortex, left dorsolateral prefrontal cortex, right inferior parietal lobule in treatment group. Higher fALFF was observed in the right inferior parietal lobule. In the placebo group lower ALFF was observed in bilateral cerebellum posterior lobe and left posterior cingulated cortex. Alzheimer's Disease Assessment Scale-Cognitive section was closely correlated with ALFF in left cerebellum posterior lobe and right cerebellum posterior lobe. Conclusion: These results indicated improved neuronal activity in some brain areas could be achieved in AD after treatment of electroencephalograph bionic electrical stimulation. The change of BOLD-fMRI signal might provide a potential imaging strategy for studying neural mechanisms of electroencephalograph bionic electrical stimulation for AD. Keywords: Electroencephalograph bionic electrical stimulation, Alzheimer's disease, Low-frequency fluctuation, Fraction low-frequency fluctuation
Bradley Russell Buchsbaum
Full Text Available The most recently encountered information is often most easily remembered in psychological tests of memory. Recent investigations of the neural basis of such recency effects have shown that activation in the lateral inferior parietal cortex (LIPC tracks the recency of a probe item when subjects make recognition memory judgments. A key question regarding recency effects in the LIPC is whether they fundamentally reflect the storage (and strength of information in memory, or whether such effects are a consequence of task difficulty or an upswing in resting state network activity. Using functional magnetic resonance imaging (fMRI we show that recency effects in the LIPC are independent of the difficulty of recognition memory decisions, that they are not a by-product of an increase in resting state network activity, and that they appear to dissociate from regions known to be involved in verbal working memory maintenance. We conclude with a discussion of two alternative explanations – the memory strength and expectancy hypotheses, respectively -- of the parietal lobe recency effect.
Full Text Available BACKGROUND: Cerebral activation during planning of reaching movements occurs both in the superior parietal lobule (SPL and premotor cortex (PM, and their activation seems to take place in parallel. METHODOLOGY: The activation of the SPL and PM has been investigated using transcranial magnetic stimulation (TMS during planning of reaching movements under visual guidance. PRINCIPAL FINDINGS: A facilitory effect was found when TMS was delivered on the parietal cortex at about half of the time from sight of the target to hand movement, independently of target location in space. Furthermore, at the same stimulation time, a similar facilitory effect was found in PM, which is probably related to movement preparation. CONCLUSIONS: This data contributes to the understanding of cortical dynamics in the parieto-frontal network, and suggests that it is possible to interfere with the planning of reaching movements at different cortical points within a particular time window. Since similar effects may be produced at similar times on both the SPL and PM, parallel processing of visuomotor information is likely to take place in these regions.
Sarkheil, Pegah; Goebel, Rainer; Schneider, Frank; Mathiak, Klaus
Facial expressions convey important emotional and social information and are frequently applied in investigations of human affective processing. Dynamic faces may provide higher ecological validity to examine perceptual and cognitive processing of facial expressions. Higher order processing of emotional faces was addressed by varying the task and virtual face models systematically. Blood oxygenation level-dependent activation was assessed using functional magnetic resonance imaging in 20 healthy volunteers while viewing and evaluating either emotion or gender intensity of dynamic face stimuli. A general linear model analysis revealed that high valence activated a network of motion-responsive areas, indicating that visual motion areas support perceptual coding for the motion-based intensity of facial expressions. The comparison of emotion with gender discrimination task revealed increased activation of inferior parietal lobule, which highlights the involvement of parietal areas in processing of high level features of faces. Dynamic emotional stimuli may help to emphasize functions of the hypothesized 'extended' over the 'core' system for face processing.
Goard, Michael J; Pho, Gerald N; Woodson, Jonathan; Sur, Mriganka
Mapping specific sensory features to future motor actions is a crucial capability of mammalian nervous systems. We investigated the role of visual (V1), posterior parietal (PPC), and frontal motor (fMC) cortices for sensorimotor mapping in mice during performance of a memory-guided visual discrimination task. Large-scale calcium imaging revealed that V1, PPC, and fMC neurons exhibited heterogeneous responses spanning all task epochs (stimulus, delay, response). Population analyses demonstrated unique encoding of stimulus identity and behavioral choice information across regions, with V1 encoding stimulus, fMC encoding choice even early in the trial, and PPC multiplexing the two variables. Optogenetic inhibition during behavior revealed that all regions were necessary during the stimulus epoch, but only fMC was required during the delay and response epochs. Stimulus identity can thus be rapidly transformed into behavioral choice, requiring V1, PPC, and fMC during the transformation period, but only fMC for maintaining the choice in memory prior to execution.
Martinaud, Olivier; Mirlink, Nicolas; Bioux, Sandrine; Bliaux, Evangéline; Lebas, Axel; Gerardin, Emmanuel; Hannequin, Didier
Only seven cases of agnosia for mirror stimuli have been reported, always with an extensive lesion. We report a new case of an agnosia for mirror stimuli due to a circumscribed lesion. An extensive battery of neuropsychological tests and a new experimental procedure to assess visual object mirror and orientation discrimination were assessed 10 days after the onset of clinical symptoms, and 5 years later. The performances of our patient were compared with those of four healthy control subjects matched for age. This test revealed an agnosia for mirror stimuli. Brain imaging showed a small right occipitoparietal hematoma, encompassing the extrastriate cortex adjoining the inferior parietal lobe. This new case suggests that: (i) agnosia for mirror stimuli can persist for 5 years after onset and (ii) the posterior part of the right intraparietal sulcus could be critical in the cognitive process of mirror stimuli discrimination. © The Author 2014. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: firstname.lastname@example.org.
The anatomy and function of the angular gyrus (Brodmann Area 39) and supramarginal gyrus (Brodmann Area 40) are described here. Both gyri constitute the inferior part of the parietal lobe. Association fibers from the angular gyrus project to the dorsolateral prefrontal cortex via the superior longitudinal fasciculus (SLF) II/arcuate fasciculus (AF), whereas those from the supramarginal gyrus project to the ventrolateral prefrontal cortex via SLF III/AF. Damage to the left angular gyrus causes kanji agraphia (lexical agraphia) and mild anomia, whereas damage to the left supramarginal gyrus causes kana alexia (phonological dyslexia) and kana agraphia (phonological agraphia). Damage to either gyrus causes Gerstmann's syndrome (finger agnosia, left-right disorientation, agraphia and acalculia) and verbal short-term memory impairment. "Angular alexia with agraphia" results from damage to the middle occipital gyrus posterior to the angular gyrus. Alexia and agraphia, with lesions in the angular or supramarginal gyrus, are characterized by kana transposition errors in reading words, which suggests the impairment of sequential phonological processing.
Ostapchenko, L I; Drobins'ka, O V; Chaĭka, V O; Bohun, L I; Bohdanova, O V; Kot, L I; Haĭda, L M
The goal of the presented work was the research of signal transduction mechanism in the rat gastric parietal cells under stomach ulcer conditions. In these cells activation of adenylate cyclase (increase of cAMP level and proteinkinase A activity) and phosphoinositide (increases [Ca2+]i; cGMP and phoshatidylinocitole levels; proteinkinase C, proteinkinase G, and calmodulin-dependent-proteinkinase activity) of signals pathway was shown. An increase of plasma membrane phospholipids (PC, PS, PE, PI, LPC) level was shown. Under conditions of influence of the stress factor the membran enzymes activity (H+, K+ -ATPase, 5'-AMPase, Na+, K+ -ATPase, Ca2+, Mg2+ -ATPase and H+, K+ -ATPase) was considerably increased. The intensification of lipid peroxidation processes in rats was demonstrated.
Roland, P E; Friberg, L
midtemporal cortex exclusively during jingle thinking. The intermediate and remote visual association areas, the superior occipital, posterior inferior temporal, and posterior superior parietal cortex, increased their rCBF exclusively during route-finding thinking. We observed no decreases in rCBF. All r......These experiments were undertaken to demonstrate that pure mental activity, thinking, increases the cerebral blood flow and that different types of thinking increase the regional cerebral blood flow (rCBF) in different cortical areas. As a first approach, thinking was defined as brain work...... communication with the outside world. In 50-3 thinking, the subjects started with 50 and then, in their minds only, continuously subtracted 3 from the result. In jingle thinking the subjects internally jumped every second word in a nine-word circular jingle. In route-finding thinking the subjects imagined...
Full Text Available In verbal communication, not only the meaning of the words convey information, but also the tone of voice (prosody conveys crucial information about the emotional state and intentions of others. In various studies right frontal and right temporal regions have been found to play a role in emotional prosody perception. Here, we used triple-pulse repetitive transcranial magnetic stimulation (rTMS to shed light on the precise time course of involvement of the right anterior superior temporal gyrus and the right fronto-parietal operculum. We hypothesized that information would be processed in the right anterior superior temporal gyrus before being processed in the right fronto-parietal operculum. Right-handed healthy subjects performed an emotional prosody task. During listening to each sentence a triplet of TMS pulses was applied to one of the regions at one of six time points (400-1900 ms. Results showed a significant main effect of Time for right anterior superior temporal gyrus and right fronto-parietal operculum. The largest interference was observed half-way through the sentence. This effect was stronger for withdrawal emotions than for the approach emotion. A further experiment with the inclusion of an active control condition, TMS over the EEG site POz (midline parietal-occipital junction, revealed stronger effects at the fronto-parietal operculum and anterior superior temporal gyrus relative to the active control condition. No evidence was found for sequential processing of emotional prosodic information from right anterior superior temporal gyrus to the right fronto-parietal operculum, but the results revealed more parallel processing. Our results suggest that both right fronto-parietal operculum and right anterior superior temporal gyrus are critical for emotional prosody perception at a relatively late time period after sentence onset. This may reflect that emotional cues can still be ambiguous at the beginning of sentences, but become
Hoekert, Marjolijn; Bais, Leonie; Kahn, René S; Aleman, André
In verbal communication, not only the meaning of the words convey information, but also the tone of voice (prosody) conveys crucial information about the emotional state and intentions of others. In various studies right frontal and right temporal regions have been found to play a role in emotional prosody perception. Here, we used triple-pulse repetitive transcranial magnetic stimulation (rTMS) to shed light on the precise time course of involvement of the right anterior superior temporal gyrus and the right fronto-parietal operculum. We hypothesized that information would be processed in the right anterior superior temporal gyrus before being processed in the right fronto-parietal operculum. Right-handed healthy subjects performed an emotional prosody task. During listening to each sentence a triplet of TMS pulses was applied to one of the regions at one of six time points (400-1900 ms). Results showed a significant main effect of Time for right anterior superior temporal gyrus and right fronto-parietal operculum. The largest interference was observed half-way through the sentence. This effect was stronger for withdrawal emotions than for the approach emotion. A further experiment with the inclusion of an active control condition, TMS over the EEG site POz (midline parietal-occipital junction), revealed stronger effects at the fronto-parietal operculum and anterior superior temporal gyrus relative to the active control condition. No evidence was found for sequential processing of emotional prosodic information from right anterior superior temporal gyrus to the right fronto-parietal operculum, but the results revealed more parallel processing. Our results suggest that both right fronto-parietal operculum and right anterior superior temporal gyrus are critical for emotional prosody perception at a relatively late time period after sentence onset. This may reflect that emotional cues can still be ambiguous at the beginning of sentences, but become more apparent half
Paulina M Kowalewska
Full Text Available BACKGROUND: The heparan sulfate proteoglycan syndecan-1 (CD138 was shown to regulate inflammatory responses by binding chemokines and cytokines and interacting with adhesion molecules, thereby modulating leukocyte trafficking to tissues. The objectives of this study were to examine the expression of syndecan-1 and its role in leukocyte recruitment and chemokine presentation in the microcirculation underlying the parietal peritoneum. METHODS: Wild-type BALB/c and syndecan-1 null mice were stimulated with an intraperitoneal injection of Staphylococcus aureus LTA, Escherichia coli LPS or TNFα and the microcirculation of the parietal peritoneum was examined by intravital microscopy after 4 hours. Fluorescence confocal microscopy was used to examine syndecan-1 expression in the peritoneal microcirculation using fluorescent antibodies. Blocking antibodies to adhesion molecules were used to examine the role of these molecules in leukocyte-endothelial cell interactions in response to LTA. To determine whether syndecan-1 co-localizes with chemokines in vivo, fluorescent antibodies to syndecan-1 were co-injected intravenously with anti-MIP-2 (CXCL2, anti-KC (CXCL1 or anti-MCP-1 (CCL2. RESULTS AND CONCLUSION: Syndecan-1 was localized to the subendothelial region of peritoneal venules and the mesothelial layer. Leukocyte rolling was significantly decreased with LPS treatment while LTA and TNFα significantly increased leukocyte adhesion compared with saline control. Leukocyte-endothelial cell interactions were not different in syndecan-1 null mice. Antibody blockade of β2 integrin (CD18, ICAM-1 (CD54 and VCAM-1 (CD106 did not decrease leukocyte adhesion in response to LTA challenge while blockade of P-selectin (CD62P abrogated leukocyte rolling. Lastly, MIP-2 expression in the peritoneal venules was not dependent on syndecan-1 in vivo. Our data suggest that syndecan-1 is expressed in the parietal peritoneum microvasculature but does not regulate leukocyte
Paul, J; Kanotra, Sohit Paul; Kanotra, Sonika
The traditional method of management of posterior epistaxis has been with anteroposterior nasal packing. Apart from the high failure rate of 26-50% reported in various series, nasal packing is associated with marked discomfort and several complications. In order to avoid nasal packing, we started doing endoscopic cauterization in cases of posterior epistaxis. A total of 23 patients with posterior epistaxis were subjected to nasal endoscopy with the intent to stop bleeding by cauterization of the bleeding vessel. Of these, in four cases unsuspected diagnosis was made. Of the remaining 19, in three patients, the bleeding point could not be localized accurately and these patients were managed by anteroposterior packing. The rest of the 16 patients were managed by endoscopic cauterization. In four patients, there was recurrence of bleeding within 24 h. In one of these, cauterization controlled the bleeding while in the rest nasal packing had to be resorted to. Thus, of the 23 patients of posterior epistaxis subjected to nasal endoscopy, we could avoid nasal packing in 17 (74%). To conclude, endoscopic nasal cauterization is recommended as the first line to treatment in all cases of posterior epistaxis. This will not only prevent the uncomfortable and potentially dangerous nasal packing but also help in finding the underlying pathology.
Wewer, U M; Tichy, D; Damjanov, A
Two monoclonal antibodies (LAM-A and LAM-B) specific for laminin from normal and neoplastic parietal yolk sac (PYS) cells were produced in rats immunized with a mouse yolk sac carcinoma cell line. Both antibodies immunoprecipitated the 400,000- and 200,000-Da chains of laminin and reacted...... with purified PYS laminin in ELISA. LAM-A reacted with mouse and rat PYS laminin, whereas LAM-B reacted only with mouse PYS laminin. Formaldehyde- and methanol-fixed adult and fetal somatic tissues were immunohistochemically unreactive with either of the two antibodies. In acetone-fixed tissue sections, both...
Harasawa, Masamitsu; Shioiri, Satoshi
The effect of the visual hemifield to which spatial attention was oriented on the activities of the posterior parietal and occipital visual cortices was examined using functional near-infrared spectroscopy in order to investigate the neural substrates of voluntary visuospatial attention. Our brain imaging data support the theory put forth in a previous psychophysical study, namely, the attentional resources for the left and right visual hemifields are distinct. Increasing the attentional load asymmetrically increased the brain activity. Increase in attentional load produced a greater increase in brain activity in the case of the left visual hemifield than in the case of the right visual hemifield. This asymmetry was observed in all the examined brain areas, including the right and left occipital and parietal cortices. These results suggest the existence of asymmetrical inhibitory interactions between the hemispheres and the presence of an extensive inhibitory network. Copyright © 2011 Elsevier Inc. All rights reserved.
Full Text Available BACKGROUND AND PURPOSE Posterior Reversible Encephalopathy Syndrome (PRES is a neurotoxic state that occurs secondary to the inability of posterior circulation to autoregulate. The clinical spectrum and the underlying pathophysiology are still poorly defined. No conclusive evidence has been put forward regarding the relationship between clinical conditions and specific imaging findings of severity or location of oedema. PURPOSE To assess the role of computed tomography in evaluation of Posterior Reversible Encephalopathy Syndrome. MATERIALS AND METHODS 55 patients referred to the Department of Radio-Diagnosis, with a history of neurological abnormalities, including altered mental function, visual loss, stupor with a predisposing history favouring PRES and followed up for a period of 10 – 30 days. RESULTS 21 patients (38.2% were females. 32 patients (58.1% were in the age group between 21 to 30 years. Predisposing condition; 16 (29.1% presented with pre-eclampsia, 12 (21.8% with post-partum status in altered sensorium, 9 (16.4% with seizures, 7 (12.7% with hypertension, 6 (10.9% with visual disturbances, 4 (7.3% with eclampsia and 1 (1.8% with uraemia. 20 cases (36.4% showed findings suggestive of posterior reversible encephalopathy syndrome on initial computed tomography examination. 35 cases showed no initial radiological evidence suggestive of posterior reversible encephalopathy syndrome. Of the 20 cases which showed computed tomographic evidence of posterior reversible encephalopathy syndrome, recovery was noted in 5 cases (9.1%. Persistence of findings detected on first CT was noted in 13 patients (23.6%. Regional predominance of the lesions was as follows. Frontal lobe (39%, Parietal lobe (32%, Temporal lobe (15% and occipital lobe (15%. CONCLUSION Varied clinical manifestations are associated with anatomical findings recognisable by neuro-imaging as PRES. Prompt imaging is necessary for the recognition of the condition and appropriate
Yin, Dazhi; Liu, Wenjing; Zeljic, Kristina; Wang, Zhiwei; Lv, Qian; Fan, Mingxia; Cheng, Wenhong; Wang, Zheng
Extensive evidence suggests that frontoparietal regions can dynamically update their pattern of functional connectivity, supporting cognitive control and adaptive implementation of task demands. However, it is largely unknown whether this flexibly functional reconfiguration is intrinsic and occurs even in the absence of overt tasks. Based on recent advances in dynamics of resting-state functional resonance imaging (fMRI), we propose a probabilistic framework in which dynamic reconfiguration of intrinsic functional connectivity between each brain region and others can be represented as a probability distribution. A complexity measurement (i.e., entropy) was used to quantify functional flexibility, which characterizes heterogeneous connectivity between a particular region and others over time. Following this framework, we identified both functionally flexible and specialized regions over the human life span (112 healthy subjects from 13 to 76 years old). Across brainwide regions, we found regions showing high flexibility mainly in the higher-order association cortex, such as the lateral prefrontal cortex (LPFC), lateral parietal cortex, and lateral temporal lobules. In contrast, visual, auditory, and sensory areas exhibited low flexibility. Furthermore, we observed that flexibility of the right LPFC improved during maturation and reduced due to normal aging, with the opposite occurring for the left lateral parietal cortex. Our findings reveal dissociable changes of frontal and parietal cortices over the life span in terms of inherent functional flexibility. This study not only provides a new framework to quantify the spatiotemporal behavior of spontaneous brain activity, but also sheds light on the organizational principle behind changes in brain function across the human life span. Recent neuroscientific research has demonstrated that the human capability of adaptive task control is primarily the result of the flexible operation of frontal brain networks. However
Ishii, Kazunari; Sasaki, Masahiro; Yamaji, Shigeru; Sakamoto, Setsu; Kitagaki, Hajime; Mori, Etsuro
Although decreased posterior cingulate metabolism in Alzheimer's disease (AD) has been previously reported, there have been no reports on posterior cingulate perfusion. In this study we evaluated posterior cingulate perfusion as a relative value using statistical parametric maps (SPMs) and as an absolute value using conventional region of interest (ROI) settings. Twenty-eight subjects, including 14 patients with mild AD (mean age: 66.4±12.1 years) and 14 normal controls (65.9±7.3 years) were studied. Regional cerebral blood flow (CBF) was measured with H 2 15 O and positron emission tomography (PET). In the SPM analysis, the left posterior cingulate and left parietotemporal CBFs were significantly decreased in the patients with mild AD (P<0.001). At a lower statistical threshold (P<0.05), the right posterior cingulate and right parietotemporal CBFs were also significantly decreased in the AD patients. In the ROI studies, the left parietal and posterior cingulate CBFs in the patients with mild AD were significantly lower than those of the normal controls by analysis of variance and post-hoc Scheffe's test (P<0.001). We conclude that posterior cingulate perfusion is decreased in mild AD, reflecting the pathological changes and metabolic reduction in the posterior cingulate gyrus that have previously been reported to occur in mild AD. (orig.). With 1 fig., 2 tabs
Beil, W.; Sewing, K. F.
The cellular and subcellular distributions of adenosinetriphosphatases (ATPases) were examined in guinea-pig gastric mucosal cells. All cell types displayed Mg2+-ATPase and bicarbonate (HCO3-)-stimulated ATPase activity. K+-ATPase was located only in fractions derived from parietal cells. Differential and density-gradient centrifugation of material prepared from parietal cells revealed that K+-ATPase activity was located in a tubulo-vesicular membrane fraction. Enzyme activity was ten fold greater in this fraction than in a crude parietal cell homogenate. The substituted benzimidazoles, omeprazole and picoprazole, inhibited K+-ATPase (IC50 1.8 +/- 0.5 mumol l-1 and 3.1 +/- 0.4 mumol l-1, respectively). Detailed kinetic analysis indicated that these compounds were non-competitive and reversible inhibitors of the enzyme. In contrast cimetidine and verapamil were without effect on the enzyme. The relevance of the inhibition of K+-ATPase to the antisecretory activity of the benzimidazoles, in experimental animals and man, is discussed. PMID:6146367
Full Text Available Background. Posterior fossa epidural hematomas represent 7-14% of all traumatic intracranial epidural hematomas. They are most frequently encountered posttraumatic mass lesions in the posterior fossa. The aim of this study was to identify clinical features that could lead to the early diagnosis of posterior fossa epidural hematoma. Methods. Between 1980 and 2002, 28 patients with epidural hematoma of the posterior fossa were operated on at the Institute for Neurosurgery, Belgrade. Clinical course neuroradiological investigations, and the results of surgical treatment of the patients with posterior fossa epidural hematomas were analyzed retrospectively. Results. Almost two thirds of patients were younger than 16 years of age. In 20 cases injury was caused by a fall, in 6 cases by a traffic accident, and in 2 by the assault. Clinical course was subacute or chronic in two thirds of the patients. On the admission Glasgow Coma Scale was 7 or less in 9 injured, 8-14 in 14 injured, and 15 in 5 injured patients. Linear fracture of the occipital bone was radiographically evident in 19 patients, but was intraoperatively encountered in all the patients except for a 4-year old child. In 25 patients the diagnosis was established by computer assisted tomography (CAT and in 3 by vertebral angiography. All the patients were operated on via suboccipital craniotomy. Four injured patients who were preoperatively comatose were with lethal outcome. Postoperatively, 24 patients were with sufficient neurologic recovery. Conclusion. Posterior fossa epidural hematoma should be suspected in cases of occipital injury, consciousness disturbances, and occipital bone fracture. In such cases urgent CAT-scan is recommended. Early recognition early diagnosis, and prompt treatment are crucial for good neurological recovery after surgery.
Engel, Oliver; Fisch, Margit
Posterior urethroplasty is the most common strategy for the treatment of post-traumatic urethral injuries. Especially in younger patients, post-traumatic injuries are a common reason for urethral strictures caused by road traffic accidents, with pelvic fracture or direct trauma to the perineum. In many cases early endoscopic realignment is the first attempt to restore the junction between proximal and distal urethra, but in some cases primary realignment is not possible or not enough to treat the urethral injury. In these cases suprapubic cystostomy alone and delayed repair by stricture excision and posterior urethroplasty is an alternative procedure to minimise the risk of stricture recurrence.
GUNGOR, Serdal; KILIC, Betul; TABEL, Yilmaz; SELIMOGLU, Ayse; OZGEN, Unsal; YILMAZ, Sezai
Objective Posterior reversible encephalopathy syndrome (PRES) is characterized by typical radiologic findings in the posterior regions of the cerebral hemispheres and cerebellum. The symptoms include headache, nausea, vomiting, visual disturbances, focal neurologic deficits, and seizures. The aim of this study is to evaluate the clinical and radiological features of PRES in children and to emphasize the recognition of atypical features. Materials & Methods We retrospectively examined 23 children with PRES from Mar 2010-Apr 2015 in Inonu University Turgut Ozal Medical Center in Turkey. We compared the clinical features and cranial MRI findings between underlying diseases of PRES. Results The most common precipitating factors were hypertension (78.2%) and medications, namely immunosuppressive and antineoplastic agents (60.8%). Manifestations included mental changes (100%), seizures (95.6%), headache (60.8%), and visual disturbances (21.7%) of mean 3.6 (range 1-10) days' duration. Cranial magnetic resonance imaging (MRI) showed bilateral occipital lesions in all patients, associated in 82.6% with less typical distribution of lesions in frontal, temporal or parietal lobes, cerebellum, corpus callosum, basal ganglia, thalamus, and brain stem. Frontal involvement was predominant, observed in 56.5% of patients. Clinical recovery was followed by radiologic resolution in all patients. Conclusion PRES is often unsuspected by the clinician, thus radiologists may be the first to suggest this diagnosis on an MRI obtained for seizures or encephalopathy. Atypical MRI finding is seen quite often. Rapid diagnosis and treatment are required to avoid a devastating outcome. PMID:29379559
Scharinger, Mathias; Henry, Molly J; Erb, Julia; Meyer, Lars; Obleser, Jonas
Auditory categorization is a vital skill involving the attribution of meaning to acoustic events, engaging domain-specific (i.e., auditory) as well as domain-general (e.g., executive) brain networks. A listener's ability to categorize novel acoustic stimuli should therefore depend on both, with the domain-general network being particularly relevant for adaptively changing listening strategies and directing attention to relevant acoustic cues. Here we assessed adaptive listening behavior, using complex acoustic stimuli with an initially salient (but later degraded) spectral cue and a secondary, duration cue that remained nondegraded. We employed voxel-based morphometry (VBM) to identify cortical and subcortical brain structures whose individual neuroanatomy predicted task performance and the ability to optimally switch to making use of temporal cues after spectral degradation. Behavioral listening strategies were assessed by logistic regression and revealed mainly strategy switches in the expected direction, with considerable individual differences. Gray-matter probability in the left inferior parietal lobule (BA 40) and left precentral gyrus was predictive of "optimal" strategy switch, while gray-matter probability in thalamic areas, comprising the medial geniculate body, co-varied with overall performance. Taken together, our findings suggest that successful auditory categorization relies on domain-specific neural circuits in the ascending auditory pathway, while adaptive listening behavior depends more on brain structure in parietal cortex, enabling the (re)direction of attention to salient stimulus properties. © 2013 Published by Elsevier Ltd.
Potgieser, Adriaan R. E.; van der Hoorn, Anouk; de Jong, Bauke M.
Background Writing is a sequential motor action based on sensorimotor integration in visuospatial and linguistic functional domains. To test the hypothesis of lateralized circuitry concerning spatial and language components involved in such action, we employed an fMRI paradigm including writing and drawing with each hand. In this way, writing-related contributions of dorsal and ventral premotor regions in each hemisphere were assessed, together with effects in wider distributed circuitry. Given a right-hemisphere dominance for spatial action, right dorsal premotor cortex dominance was expected in left-hand writing while dominance of the left ventral premotor cortex was expected during right-hand writing. Methods Sixteen healthy right-handed subjects were scanned during audition-guided writing of short sentences and simple figure drawing without visual feedback. Tapping with a pencil served as a basic control task for the two higher-order motor conditions. Activation differences were assessed with Statistical Parametric Mapping (SPM). Results Writing and drawing showed parietal-premotor and posterior inferior temporal activations in both hemispheres when compared to tapping. Drawing activations were rather symmetrical for each hand. Activations in left- and right-hand writing were left-hemisphere dominant, while right dorsal premotor activation only occurred in left-hand writing, supporting a spatial motor contribution of particularly the right hemisphere. Writing contrasted to drawing revealed left-sided activations in the dorsal and ventral premotor cortex, Broca’s area, pre-Supplementary Motor Area and posterior middle and inferior temporal gyri, without parietal activation. Discussion The audition-driven postero-inferior temporal activations indicated retrieval of virtual visual form characteristics in writing and drawing, with additional activation concerning word form in the left hemisphere. Similar parietal processing in writing and drawing pointed at a
Potgieser, Adriaan R E; van der Hoorn, Anouk; de Jong, Bauke M
Writing is a sequential motor action based on sensorimotor integration in visuospatial and linguistic functional domains. To test the hypothesis of lateralized circuitry concerning spatial and language components involved in such action, we employed an fMRI paradigm including writing and drawing with each hand. In this way, writing-related contributions of dorsal and ventral premotor regions in each hemisphere were assessed, together with effects in wider distributed circuitry. Given a right-hemisphere dominance for spatial action, right dorsal premotor cortex dominance was expected in left-hand writing while dominance of the left ventral premotor cortex was expected during right-hand writing. Sixteen healthy right-handed subjects were scanned during audition-guided writing of short sentences and simple figure drawing without visual feedback. Tapping with a pencil served as a basic control task for the two higher-order motor conditions. Activation differences were assessed with Statistical Parametric Mapping (SPM). Writing and drawing showed parietal-premotor and posterior inferior temporal activations in both hemispheres when compared to tapping. Drawing activations were rather symmetrical for each hand. Activations in left- and right-hand writing were left-hemisphere dominant, while right dorsal premotor activation only occurred in left-hand writing, supporting a spatial motor contribution of particularly the right hemisphere. Writing contrasted to drawing revealed left-sided activations in the dorsal and ventral premotor cortex, Broca's area, pre-Supplementary Motor Area and posterior middle and inferior temporal gyri, without parietal activation. The audition-driven postero-inferior temporal activations indicated retrieval of virtual visual form characteristics in writing and drawing, with additional activation concerning word form in the left hemisphere. Similar parietal processing in writing and drawing pointed at a common mechanism by which such visually
Gorgoni, Maurizio; Lauri, Giulia; Truglia, Ilaria; Cordone, Susanna; Sarasso, Simone; Scarpelli, Serena; Mangiaruga, Anastasia; D'Atri, Aurora; Tempesta, Daniela; Ferrara, Michele; Marra, Camillo; Rossini, Paolo Maria; De Gennaro, Luigi
Several studies have identified two types of sleep spindles: fast (13–15 Hz) centroparietal and slow (11–13 Hz) frontal spindles. Alterations in spindle activity have been observed in Alzheimer's disease (AD) and Mild Cognitive Impairment (MCI). Only few studies have separately assessed fast and slow spindles in these patients showing a reduction of fast spindle count, but the possible local specificity of this phenomenon and its relation to cognitive decline severity are not clear. Moreover, fast and slow spindle density have never been assessed in AD/MCI. We have assessed fast and slow spindles in 15 AD patients, 15 amnesic MCI patients, and 15 healthy elderly controls (HC). Participants underwent baseline polysomnographic recording (19 cortical derivations). Spindles during nonrapid eye movements sleep were automatically detected, and spindle densities of the three groups were compared in the derivations where fast and slow spindles exhibited their maximum expression (parietal and frontal, resp.). AD and MCI patients showed a significant parietal fast spindle density decrease, positively correlated with Minimental State Examination scores. Our results suggest that AD-related changes in spindle density are specific for frequency and location, are related to cognitive decline severity, and may have an early onset in the pathology development. PMID:27066274
Full Text Available Parkinson's disease (PD is characterized by typical extrapyramidal motor features and increasingly recognized non-motor symptoms such as working memory (WM deficits. Using functional magnetic resonance imaging (fMRI, we investigated differences in neuronal activation during a motor WM task in 23 non-demented PD patients and 23 age- and gender-matched healthy controls. Participants had to memorize and retype variably long visuo-spatial stimulus sequences after short or long delays (immediate or delayed serial recall. PD patients showed deficient WM performance compared to controls, which was accompanied by reduced encoding-related activation in WM-related regions. Mirroring slower motor initiation and execution, reduced activation in motor structures such as the basal ganglia and superior parietal cortex was detected for both immediate and delayed recall. Increased activation in limbic, parietal and cerebellar regions was found during delayed recall only. Increased load-related activation for delayed recall was found in the posterior midline and the cerebellum. Overall, our results demonstrate that impairment of WM in PD is primarily associated with a widespread reduction of task-relevant activation, whereas additional parietal, limbic and cerebellar regions become more activated relative to matched controls. While the reduced WM-related activity mirrors the deficient WM performance, the additional recruitment may point to either dysfunctional compensatory strategies or detrimental crosstalk from "default-mode" regions, contributing to the observed impairment.
Kaiser, Jochen; Walker, Florian; Leiberg, Susanne; Lutzenberger, Werner
In human magnetoencephalogram, we have found gamma-band activity (GBA), a putative measure of cortical network synchronization, during both bottom-up and top-down auditory processing. When sound positions had to be retained in short-term memory for 800 ms, enhanced GBA was detected over posterior parietal cortex, possibly reflecting the activation of higher sensory storage systems along the hypothesized auditory dorsal space processing stream. Additional prefrontal GBA increases suggested an involvement of central executive networks in stimulus maintenance. The present study assessed spatial echoic memory with the same stimuli but a shorter memorization interval of 200 ms. Statistical probability mapping revealed posterior parietal GBA increases at 80 Hz near the end of the memory phase and both gamma and theta enhancements in response to the test stimulus. In contrast to the previous short-term memory study, no prefrontal gamma or theta enhancements were detected. This suggests that spatial echoic memory is performed by networks along the putative auditory dorsal stream, without requiring an involvement of prefrontal executive regions.
Nibourg, Lisanne M; Gelens, Edith; Kuijer, Roelof; Hooymans, Johanna Mm; van Kooten, Theo G; Koopmans, Steven A
Posterior capsular opacification (PCO) is a common complication of cataract surgery. The development of PCO is due to a combination of the processes of proliferation, migration, and transdifferentiation of residual lens epithelial cells (LECs) on the lens capsule. In the past decades, various forms
Nov 4, 2013 ... crinology with short stature, delayed bone age and biochemical features suggestive of hypo pituitarism. Magnetic resonance imaging of the brain demonstrated a flattened anterior pituitary gland within the sella, associated with absence of the infundibular stalk and an ectopic posterior pituitary gland (Fig.
Mainjot, Amélie; Vanheusden, Alain
Posterior ceramic bonded partial restorations are conservative and esthetic approaches for compromised teeth. Overlays constitute a less invasive alternative for tooth tissues than crown preparations. With inlays and onlays they are also indicated in case of full arch or quadrant rehabilitations including several teeth. This article screens indications and realization of this type of restorations.
Smeets, Bart; Kuppe, Christoph; Sicking, Eva-Maria; Fuss, Astrid; Jirak, Peggy; van Kuppevelt, Toin H.; Endlich, Karlhans; Wetzels, Jack F.M.; Gröne, Hermann-Josef; Floege, Jürgen
The pathogenesis of the development of sclerotic lesions in focal segmental glomerulosclerosis (FSGS) remains unknown. Here, we selectively tagged podocytes or parietal epithelial cells (PECs) to determine whether PECs contribute to sclerosis. In three distinct models of FSGS (5/6-nephrectomy + DOCA-salt; the murine transgenic chronic Thy1.1 model; or the MWF rat) and in human biopsies, the primary injury to induce FSGS associated with focal activation of PECs and the formation of cellular adhesions to the capillary tuft. From this entry site, activated PECs invaded the affected segment of the glomerular tuft and deposited extracellular matrix. Within the affected segment, podocytes were lost and mesangial sclerosis developed within the endocapillary compartment. In conclusion, these results demonstrate that PECs contribute to the development and progression of the sclerotic lesions that define FSGS, but this pathogenesis may be relevant to all etiologies of glomerulosclerosis. PMID:21719782
West, R; Bell, M A
Groups of healthy, community-dwelling younger and older adults performed a Stroop task in which color and word could be congruent or incongruent and spatially integrated or separated. During the task, continuous electroencephalogram (EEG) was recorded from frontal, parietal, and occipital regions. The magnitude of the Stroop interference effect and task-related EEG activation was greater for older than younger adults when stimuli were integrated. This effect was significant over medial and lateral frontal and parietal, but not occipital, regions. In comparison, interference and EEG activation did not differ for younger and older adults when stimuli were separated. These findings support the hypothesis that the anterior attention system is more sensitive to the effects of increasing age than the posterior attention system.
Brown, Thackery I; Rissman, Jesse; Chow, Tiffany E; Uncapher, Melina R; Wagner, Anthony D
Autobiographical remembering can depend on two forms of memory: episodic (event) memory and autobiographical semantic memory (remembering personally relevant semantic knowledge, independent of recalling a specific experience). There is debate about the degree to which the neural signals that support episodic recollection relate to or build upon autobiographical semantic remembering. Pooling data from two fMRI studies of memory for real-world personal events, we investigated whether medial temporal lobe (MTL) and parietal subregions contribute to autobiographical episodic and semantic remembering. During scanning, participants made memory judgments about photograph sequences depicting past events from their life or from others' lives, and indicated whether memory was based on episodic or semantic knowledge. Results revealed several distinct functional patterns: activity in most MTL subregions was selectively associated with autobiographical episodic memory; the hippocampal tail, superior parietal lobule, and intraparietal sulcus were similarly engaged when memory was based on retrieval of an autobiographical episode or autobiographical semantic knowledge; and angular gyrus demonstrated a graded pattern, with activity declining from autobiographical recollection to autobiographical semantic remembering to correct rejections of novel events. Collectively, our data offer insights into MTL and parietal cortex functional organization, and elucidate circuitry that supports different forms of real-world autobiographical memory.
Shakespeare, Timothy J; Yong, Keir X X; Foxe, David; Hodges, John; Crutch, Sebastian J
Posterior cortical atrophy (PCA) is a neurodegenerative syndrome characterized by progressive visual dysfunction and parietal, occipital, and occipitotemporal atrophy. The aim of this study was to compare the impact of PCA and typical Alzheimer's disease (tAD) on everyday functional abilities and neuropsychiatric status. The Cambridge Behavioural Inventory-Revised was given to carers of 32 PCA and 71 tAD patients. PCA patients showed significantly greater impairment in everyday skills and self-care while the tAD group showed greater impairment in aspects of memory and orientation, and motivation. We suggest that PCA poses specific challenges for those caring for people affected by the condition.
Mário S. Cademartori
Full Text Available São relatados 6 casos de hematomas sub-tentorias (um de hematoma subdural crônico, quatro de hematomas intra-cerebelares, um de hematoma extra-dural. Salientando a pequena freqüência dos hematomas da fossa craniana posterior, o autor mostra a necessidade de vários exames complementares para o diagnóstico exato, indispensável para a aplicação de terapêutica cirúrgica adequada.Six cases of sub-tentorial haematomata (one chronic sub-dural, four intra-cerebellar, one extra-dural are reported. Emphasizing the relative rarity of haematomata in the posterior cranial fossa, the author claims the necessity of complementary examinations for proper diagnosis, indispensable for adequate surgical treatment.
Sum, Jonathan C; Omid, Reza
The patient was a 25-year-old male college student with a chief complaint of right shoulder pain. The patient was initially diagnosed with bicipital tendinitis by his physician and had been treated for 4 weeks by a physical therapist. However, his symptoms did not improve and he was unable to return to his preinjury activity levels, so he sought the services of another physical therapist for a second opinion. Due to concern for a labrum tear, the physical therapist referred the patient to an orthopaedic surgeon. Magnetic resonance arthrography revealed findings consistent with a superior labrum anterior-to-posterior tear.
Zou, Qihong; Ross, Thomas J; Gu, Hong; Geng, Xiujuan; Zuo, Xi-Nian; Hong, L Elliot; Gao, Jia-Hong; Stein, Elliot A; Zang, Yu-Feng; Yang, Yihong
Although resting-state brain activity has been demonstrated to correspond with task-evoked brain activation, the relationship between intrinsic and evoked brain activity has not been fully characterized. For example, it is unclear whether intrinsic activity can also predict task-evoked deactivation and whether the rest-task relationship is dependent on task load. In this study, we addressed these issues on 40 healthy control subjects using resting-state and task-driven [N-back working memory (WM) task] functional magnetic resonance imaging data collected in the same session. Using amplitude of low-frequency fluctuation (ALFF) as an index of intrinsic resting-state activity, we found that ALFF in the middle frontal gyrus and inferior/superior parietal lobules was positively correlated with WM task-evoked activation, while ALFF in the medial prefrontal cortex, posterior cingulate cortex, superior frontal gyrus, superior temporal gyrus, and fusiform gyrus was negatively correlated with WM task-evoked deactivation. Further, the relationship between the intrinsic resting-state activity and task-evoked activation in lateral/superior frontal gyri, inferior/superior parietal lobules, superior temporal gyrus, and midline regions was stronger at higher WM task loads. In addition, both resting-state activity and the task-evoked activation in the superior parietal lobule/precuneus were significantly correlated with the WM task behavioral performance, explaining similar portions of intersubject performance variance. Together, these findings suggest that intrinsic resting-state activity facilitates or is permissive of specific brain circuit engagement to perform a cognitive task, and that resting activity can predict subsequent task-evoked brain responses and behavioral performance. Copyright © 2012 Wiley Periodicals, Inc.
Wang, Jiaojian; Yang, Yong; Fan, Lingzhong; Xu, Jinping; Li, Changhai; Liu, Yong; Fox, Peter T; Eickhoff, Simon B; Yu, Chunshui; Jiang, Tianzi
The superior parietal lobule (SPL) plays a pivotal role in many cognitive, perceptive, and motor-related processes. This implies that a mosaic of distinct functional and structural subregions may exist in this area. Recent studies have demonstrated that the ongoing spontaneous fluctuations in the brain at rest are highly structured and, like coactivation patterns, reflect the integration of cortical locations into long-distance networks. This suggests that the internal differentiation of a complex brain region may be revealed by interaction patterns that are reflected in different neuroimaging modalities. On the basis of this perspective, we aimed to identify a convergent functional organization of the SPL using multimodal neuroimaging approaches. The SPL was first parcellated based on its structural connections as well as on its resting-state connectivity and coactivation patterns. Then, post hoc functional characterizations and connectivity analyses were performed for each subregion. The three types of connectivity-based parcellations consistently identified five subregions in the SPL of each hemisphere. The two anterior subregions were found to be primarily involved in action processes and in visually guided visuomotor functions, whereas the three posterior subregions were primarily associated with visual perception, spatial cognition, reasoning, working memory, and attention. This parcellation scheme for the SPL was further supported by revealing distinct connectivity patterns for each subregion in all the used modalities. These results thus indicate a convergent functional architecture of the SPL that can be revealed based on different types of connectivity and is reflected by different functions and interactions. © 2014 Wiley Periodicals, Inc.
Derrik E Asher
Full Text Available Substantial evidence has highlighted the significant role of associative brain areas, such as the posterior parietal cortex (PPC in transforming multimodal sensory information into motor plans. However, little is known about how different sensory information, which can have different delays or be absent, combines to produce a motor plan, such as executing a reaching movement. To address these issues, we constructed four biologically plausible network architectures to simulate PPC: 1 feedforward from sensory input to the PPC to a motor output area, 2 feedforward with the addition of an efference copy from the motor area, 3 feedforward with the addition of lateral or recurrent connectivity across PPC neurons, and 4 feedforward plus efference copy, and lateral connections. Using an evolutionary strategy, the connectivity of these network architectures was evolved to execute visually guided movements, where the target stimulus provided visual input for the entirety of each trial. The models were then tested on a memory guided motor task, where the visual target disappeared after a short duration. Sensory input to the neural networks had sensory delays consistent with results from monkey studies. We found that lateral connections within the PPC resulted in smoother movements and were necessary for accurate movements in the absence of visual input. The addition of lateral connections resulted in velocity profiles consistent with those observed in human and non-human primate visually guided studies of reaching, and allowed for smooth, rapid, and accurate movements under all conditions. In contrast, Feedforward or Feedback architectures were insufficient to overcome these challenges. Our results suggest that intrinsic lateral connections are critical for executing accurate, smooth motor plans.
Full Text Available The posterior parietal cortex participates to numerous cognitive functions, from perceptual to attentional and decisional processes. However, the same functions have also been attributed to the frontal cortex. We previously conducted a series of reversible inactivations of the lateral intraparietal area (LIP and of the frontal eye field (FEF in the monkey which showed impairments in covert visual search performance, characterized mainly by an increase in the mean reaction time (RT necessary to detect a contralesional target. Only subtle differences were observed between the inactivation effects in both areas. In particular, the magnitude of the deficit was dependant of search task difficulty for LIP, but not for FEF.In the present study, we re-examine these data in order to try to dissociate the specific involvement of these two regions, by considering the entire RT distribution instead of mean RT. We use the LATER model to help us interpret the effects of the inactivations with regard to information accumulation rate and decision processes. We show that: 1 different search strategies can be used by monkeys to perform visual search, either by processing the visual scene in parallel, or by combining parallel and serial processes; 2 LIP and FEF inactivations have very different effects on the RT distributions in the two monkeys. Although our results are not conclusive with regards to the exact functional mechanisms affected by the inactivations, the effects we observe on RT distributions could be accounted by an involvement of LIP in saliency representation or decision-making, and an involvement of FEF in attentional shifts and perception. Finally, we observe that the use of the LATER model is limited in the context of a visual search as it cannot fit all the behavioural strategies encountered. We propose that the diversity in search strategies observed in our monkeys also exists in individual human subjects and should be considered in future
Iuculano, Teresa; Cohen Kadosh, Roi
Nearly 7% of the population exhibit difficulties in dealing with numbers and performing arithmetic, a condition named Developmental Dyscalculia (DD), which significantly affects the educational and professional outcomes of these individuals, as it often persists into adulthood. Research has mainly focused on behavioral rehabilitation, while little is known about performance changes and neuroplasticity induced by the concurrent application of brain-behavioral approaches. It has been shown that numerical proficiency can be enhanced by applying a small-yet constant-current through the brain, a non-invasive technique named transcranial electrical stimulation (tES). Here we combined a numerical learning paradigm with transcranial direct current stimulation (tDCS) in two adults with DD to assess the potential benefits of this methodology to remediate their numerical difficulties. Subjects learned to associate artificial symbols to numerical quantities within the context of a trial and error paradigm, while tDCS was applied to the posterior parietal cortex (PPC). The first subject (DD1) received anodal stimulation to the right PPC and cathodal stimulation to the left PPC, which has been associated with numerical performance's improvements in healthy subjects. The second subject (DD2) received anodal stimulation to the left PPC and cathodal stimulation to the right PPC, which has been shown to impair numerical performance in healthy subjects. We examined two indices of numerical proficiency: (i) automaticity of number processing; and (ii) mapping of numbers onto space. Our results are opposite to previous findings with non-dyscalculic subjects. Only anodal stimulation to the left PPC improved both indices of numerical proficiency. These initial results represent an important step to inform the rehabilitation of developmental learning disabilities, and have relevant applications for basic and applied research in cognitive neuroscience, rehabilitation, and education.
Full Text Available Nearly 7% of the population exhibit difficulties in dealing with numbers and performing arithmetic, a condition named Developmental Dyscalculia (DD, which significantly affects the educational and professional outcomes of these individuals, as it often persists into adulthood. Research has mainly focused on behavioral rehabilitation, while little is known about performance changes and neuroplasticity induced by the concurrent application of brain-behavioral approaches. It has been shown that numerical proficiency can be enhanced by applying a small – yet constant – current through the brain, a non-invasive technique named transcranial electrical stimulation (tES. Here we combined a numerical learning paradigm with transcranial direct current stimulation (tDCS in two adults with DD to assess the potential benefits of this methodology to remediate their numerical difficulties. Subjects learned to associate artificial symbols to numerical quantities within the context of a trial and error paradigm, while tDCS was applied to the posterior parietal cortex (PPC. The first subject (DD1 received anodal stimulation to the right PPC and cathodal stimulation to the left PPC, which has been associated with numerical performance’s improvements in healthy subjects. The second subject (DD2 received anodal stimulation to the left PPC and cathodal stimulation to the right PPC, which has been shown to impair numerical performance in healthy subjects. We examined two indices of numerical proficiency: (i automaticity of number processing; and (ii mapping of numbers onto space. Our results are opposite to previous findings with non-dyscalculic subjects. Only anodal stimulation to the left PPC improved both indices of numerical proficiency. These initial results represent an important step to inform the rehabilitation of developmental learning disabilities, and have relevant applications for basic and applied research in cognitive neuroscience, rehabilitation
Fabricius, Charlotte; Petersen, Anders; Iversen, Helle K
Objective: Impaired visual attention is common following strokes in the territory of the middle cerebral artery, particularly in the right hemisphere. However, attentional effects of more posterior lesions are less clear. The aim of this study was to characterize visual processing speed...... and apprehension span following posterior cerebral artery (PCA) stroke. We also relate these attentional parameters to visual word recognition, as previous studies have suggested that reduced visual speed and span may explain pure alexia. Methods: Nine patients with MR-verified focal lesions in the PCA......-territory (four left PCA; four right PCA; one bilateral, all >1 year post stroke) were compared to 25 controls using single case statistics. Visual attention was characterized by a whole report paradigm allowing for hemifield-specific speed and span measurements. We also characterized visual field defects...
Kakehashi, Akihiro; Takezawa, Mikiko; Akiba, Jun
Akihiro Kakehashi,1 Mikiko Takezawa,1 Jun Akiba21Department of Ophthalmology, Jichi Medical University, Saitama Medical Center, Saitama, 2Kanjodori Eye Clinic, Asahikawa, JapanAbstract: Diagnosing a posterior vitreous detachment (PVD) is important for predicting the prognosis and determining the indication for vitreoretinal surgery in many vitreoretinal diseases. This article presents both classifications of a PVD by slit-lamp biomicroscopy and of a shallow PVD by optical coherence tomography...
Rangi, P.S.; Partridge, W.J. [Charing Cross Hospital, Department of Imaging, London (United Kingdom); Newlands, E.S. [Charing Cross Hospital, Department of Oncology, London (United Kingdom); Waldman, A.D. [Charing Cross Hospital, Department of Imaging, London (United Kingdom); Institute of Neurology, Dementia Research Group, London (United Kingdom)
A 49-year-old woman who had previously received treatment with cytotoxic drugs for metastatic gestational trophoblastic disease (GTD) presented with a witnessed tonic-clonic seizure, headache, confusion and blindness, 6 days after the uneventful administration of a general anaesthetic and 2 months after cessation of chemotherapy. Magnetic resonance imaging showed relatively symmetrical, subcortical, white matter abnormalities, predominantly affecting the occipital, posterior temporal and parietal lobes and the cerebellum. T2-dependent abnormalities and elevated regional apparent diffusion coefficient were present in a pattern typical for posterior reversible encephalopathy syndrome (PRES). The clinical and radiological manifestations were resolved completely with supportive therapy. This case of PRES may be a late complication of gemcitabine or cisplatin therapy precipitated by a general anaesthetic, or associated electrolyte or blood pressure disturbance. (orig.)
Hasbun H, Jorge; Rodriguez G, Marcelo; Miranda G, Gonzalo
The Posterior Reversible Encephalopathy Syndrome is a neurological condition described on 1996, developed in patients with complex systemic conditions, especially pregnant women with pre eclampsia that at the same time presented neurological signs as seizures, headache, visual loss, and vomiting in addition to posterior brain edema, visible on neuroimaging and located in parietal and occipital lobes, that usually reverses completely. We present two clinical cases with Pres and eclampsia, antenatal and post-partum, both with seizure and confirmed brain edema with Nuclear Magnetic Resonance. Both had a favorable evolution after the anticonvulsant and anti-hypertensive therapy were done. We discuss the controversy over pathophysiological mechanisms, the new methods for diagnosis and management and the importance of multidisciplinary approach
Full Text Available The Gerstmann syndrome of dyscalculia, dysgraphia, left-right confusion, and finger agnosia is generally attributed to lesions near the angular gyrus of the dominant hemisphere. A 68-year-old right-handed woman presented with sudden difficulty completing a Sudoku grid and was found to have dyscalculia, dysgraphia, and left-right confusion. Magnetic resonance imaging (MRI showed a focus of abnormal reduced diffusivity in the left posterior insula and temporoparietal operculum consistent with acute infarct. Gerstmann syndrome from an insular or peri-insular lesion has not been described in the literature previously. Pathological and functional imaging studies show connections between left posterior insular region and inferior parietal lobe. We postulate that the insula and operculum lesion disrupted key functional networks resulting in a pseudoparietal presentation.
Bhattacharyya, S; Cai, X; Klein, J P
The Gerstmann syndrome of dyscalculia, dysgraphia, left-right confusion, and finger agnosia is generally attributed to lesions near the angular gyrus of the dominant hemisphere. A 68-year-old right-handed woman presented with sudden difficulty completing a Sudoku grid and was found to have dyscalculia, dysgraphia, and left-right confusion. Magnetic resonance imaging (MRI) showed a focus of abnormal reduced diffusivity in the left posterior insula and temporoparietal operculum consistent with acute infarct. Gerstmann syndrome from an insular or peri-insular lesion has not been described in the literature previously. Pathological and functional imaging studies show connections between left posterior insular region and inferior parietal lobe. We postulate that the insula and operculum lesion disrupted key functional networks resulting in a pseudoparietal presentation.
Ikeda, Yukio; Nakazawa, Shozo; Yamakawa, Kazuomi; Kobayashi, Shiro; Tsuji, Yukihide
In this paper three acute cases and two subacute cases are reported. CT findings in acute cases show two different types. ''Type I'' shows crescent or lenticular high density area which is not enhanced after contrast infusion. ''Type II'' shows lenticular low density area with membranous high density region in its medial side after contrast infusion. In subacute cases plain CT scan shows lenticular iso or low density area with membranous high density region in its medial side. Forty five cases of posterior fossa epidural hematoma in the review of literature of this country are discussed. Disturbances of the consciousness are the most predominant symptoms in acute cases, while in subacute cases cerebellar signs, vomiting, headache and choked disc are noted. Angiographical examinations may not always be valuable in collecting the direct information of the existence of the epidural hematoma. Liquor cavity in the posterior fossa which is thought to serve as a buffer action of hematoma is about 20 ml, so we discuss about the volume of hematoma, especially of 20 ml, associated with clinical course and prognosis. Volume of epidural hematoma is one of the most important factors affecting clinical course and prognosis. In summary of these our experiences, we again emphasize the value of CT scan as the rapid, noninvasive, accurate radiological examination in the diagnosis of traumatic posterior fossa epidural hematoma. (author)
Smeets, Bart; Uhlig, Sandra; Fuss, Astrid; Mooren, Fieke; Wetzels, Jack F M; Floege, Jürgen; Moeller, Marcus J
Cellular lesions form in Bowman's space in both crescentic glomerulonephritis and collapsing glomerulopathy. The pathomechanism and origin of the proliferating cells in these lesions are unknown. In this study, we examined proliferating cells by lineage tracing of either podocytes or parietal epithelial cells (PECs) in the nephrotoxic nephritis model of inflammatory crescentic glomerulonephritis. In addition, we traced the fate of genetically labeled PECs in the Thy-1.1 transgenic mouse model of collapsing glomerulopathy. In both models, cellular bridges composed of PECs were observed between Bowman's capsule and the glomerular tuft. Genetically labeled PECs also populated larger, more advanced cellular lesions. In these lesions, we detected de novo expression of CD44 in activated PECs. In contrast, we rarely identified genetically labeled podocytes within the cellular lesions of crescentic glomerulonephritis. In conclusion, PECs constitute the majority of cells that compose early extracapillary proliferative lesions in both crescentic glomerulonephritis and collapsing glomerulopathy, suggesting similar pathomechanisms in both diseases.
Full Text Available Previous brain electrophysiological research has studied the interregionalconnectivity during the tapping task and found that inter-hemispheric alpha coherence wasmore significant under bimanual task conditions than that under unilateral conditions, butthe interregional connectivity situation in the unilateral tapping condition was not exploredclearly. We have designed a unilateral repetitive finger-tapping task to delineate the anteriorand posterior cortex contributions to unilateral finger movement. Sixteen right handedcollege students participated in this study. Event related potentials (ERPs and the strengthof event related coherence (ERCoh were analyzed to examine the antero-posterodominance of cortical activity in the phase of early visual process (75-120ms, pre-execution(175-260ms, execution (310-420ms and post-execution (420-620ms. Results showed thatthe occipital (Oz, O1 and O2, frontal (Fz, F3, and F4, fronto-central (Fz, Cz, F3 and C3,and parietal regions were the most pronounced in the early visual, pre-execution, execution,and post-execution phases, respectively. Moreover, among four inter-hemispheric pairs onlythe Coh (C3 and C4 was significantly correlated to reaction time (RT of tapping in theexecution phase. In conclusion, the aforementioned variability of electrophysiological data(ERPs and coherence and the change of antero-postero regional dominance with timereflect the relative importance of different mechanisms in different phases. The mechanismsof visual processing, motor planning, motor execution and feedback reward wereoperational, respectively.
Woolgar, Alexandra; Williams, Mark A; Rich, Anina N
Selective attention is fundamental for human activity, but the details of its neural implementation remain elusive. One influential theory, the adaptive coding hypothesis (Duncan, 2001, An adaptive coding model of neural function in prefrontal cortex, Nature Reviews Neuroscience 2:820-829), proposes that single neurons in certain frontal and parietal regions dynamically adjust their responses to selectively encode relevant information. This selective representation may in turn support selective processing in more specialized brain regions such as the visual cortices. Here, we use multi-voxel decoding of functional magnetic resonance images to demonstrate selective representation of attended--and not distractor--objects in frontal, parietal, and visual cortices. In addition, we highlight a critical role for task demands in determining which brain regions exhibit selective coding. Strikingly, representation of attended objects in frontoparietal cortex was highest under conditions of high perceptual demand, when stimuli were hard to perceive and coding in early visual cortex was weak. Coding in early visual cortex varied as a function of attention and perceptual demand, while coding in higher visual areas was sensitive to the allocation of attention but robust to changes in perceptual difficulty. Consistent with high-profile reports, peripherally presented objects could also be decoded from activity at the occipital pole, a region which corresponds to the fovea. Our results emphasize the flexibility of frontoparietal and visual systems. They support the hypothesis that attention enhances the multi-voxel representation of information in the brain, and suggest that the engagement of this attentional mechanism depends critically on current task demands. Copyright © 2015 Elsevier Inc. All rights reserved.
Matsuyoshi, Daisuke; Ikeda, Takashi; Sawamoto, Nobukatsu; Kakigi, Ryusuke; Fukuyama, Hidenao; Osaka, Naoyuki
We often fail to consciously detect an unexpected object when we are engaged in an attention-demanding task (inattentional blindness). The inattentional blindness which is induced by visual short-term memory (VSTM) load has been proposed to result from a suppression of temporo-parietal junction (TPJ) activity that involves stimulus-driven attention. However, the fact that, inversely proportional to TPJ activity, intraparietal sulcus (IPS) activity correlates with VSTM load renders questionable the account of inattentional blindness based only on TPJ activity. Here, we investigated whether the TPJ is solely responsible for inattentional blindness by decoupling IPS and TPJ responses to VSTM load and then using the same manipulation to test the behavioral inattentional blindness performance. Experiment 1 showed that TPJ activity was not suppressed by task-irrelevant load while the IPS responded to both task-relevant and task-irrelevant load. Although the TPJ account of inattentional blindness predicts that the degree of inattentional blindness should track TPJ activity, we found in Experiment 2 that inattentional blindness was induced not only by task-relevant load but also by task-irrelevant load, showing inconsistency between the extent of inattentional blindness and TPJ response. These findings suggest that inattentional blindness can be induced without suppression of TPJ activity and seem to offer the possibility that the IPS contributes to conscious perception. Copyright (c) 2010 Elsevier Ltd. All rights reserved.
Full Text Available There is converging evidence that electrophysiological responses over posterior cortical regions in the 200-300 ms range distinguish between physically identical stimuli that reach consciousness or remain unseen. Here, we attempt at determining the sources of this awareness-related activity using MEG. Fourteen subjects were presented with faint colored gratings at threshold for contrast and reported on each trial whether the grating was seen or unseen. Subjects were primed with a color cue that could be congruent or incongruent with the color of the grating, to probe to what extent two co-localized features (color and orientation would be bound in consciousness. The contrast between neural responses to seen and unseen physically identical gratings revealed a sustained posterior difference between 190 and 350 ms, thereby replicating prior studies. We further show that the main sources of the awareness-related activity were localized bilaterally on the lateral convexity of the occipito-temporal region, in the lateral occipital (LO complex, as well as in the right posterior infero-temporal region. No activity differentiating seen and unseen trials could be observed in frontal or parietal regions in this latency range, even at lower threshold. Color congruency did not improve gratings' detection, and the awareness-related activity was independent from color congruency. However, at the neural level, color congruency was processed differently in grating-present and grating-absent trials. The pattern of results suggests the existence of a neural process of color congruency engaging left parietal regions that is affected by the mere presence of another feature, whether this feature reaches consciousness or not. Altogether, our results reveal an occipital source of visual awareness insensitive to color congruency, and a simultaneous parietal source not engaged in visual awareness, but sensitive to the manipulation of co-localized features.
Kubanek, Jan; Li, Jingfeng M; Snyder, Lawrence H
Parietal cortex is central to spatial cognition. Lesions of parietal cortex often lead to hemispatial neglect, an impairment of choices of targets in space. It has been unclear whether parietal cortex implements target choice at the general cognitive level, or whether parietal cortex subserves the choice of targets of particular actions. To address this question, monkeys engaged in choice tasks in two distinct action contexts--eye movements and arm movements. We placed focused reversible lesions into specific parietal circuits using the GABAA receptor agonist muscimol and validated the lesion placement using MRI. We found that lesions on the lateral bank of the intraparietal sulcus [lateral intraparietal area (LIP)] specifically biased choices made using eye movements, whereas lesions on the medial bank of the intraparietal sulcus [parietal reach region (PRR)] specifically biased choices made using arm movements. This double dissociation suggests that target choice is implemented in dedicated parietal circuits in the context of specific actions. This finding emphasizes a motor role of parietal cortex in spatial choice making and contributes to our understanding of hemispatial neglect.
Millington, Rebecca S; James-Galton, Merle; Maia Da Silva, Mari N; Plant, Gordon T; Bridge, Holly
Posterior cortical atrophy (PCA), the visual variant of Alzheimer's disease, leads to high-level visual deficits such as alexia or agnosia. Visual field deficits have also been identified, but often inconsistently reported. Little is known about the pattern of visual field deficits or the underlying cortical changes leading to this visual loss. Multi-modal magnetic resonance imaging was used to investigate differences in gray matter volume, cortical thickness, white matter microstructure and functional activity in patients with PCA compared to age-matched controls. Additional analyses investigated hemispheric asymmetries in these metrics according to the visual field most affected by the disease. Analysis of structural data indicated considerable loss of gray matter in the occipital and parietal cortices, lateralized to the hemisphere contralateral to the visual loss. This lateralized pattern of gray matter loss was also evident in the hippocampus and parahippocampal gyrus. Diffusion-weighted imaging showed considerable effects of PCA on white matter microstructure in the occipital cortex, and in the corpus callosum. The change in white matter was only lateralized in the occipital lobe, however, with greatest change in the optic radiation contralateral to the visual field deficit. Indeed, there was a significant correlation between the laterality of the optic radiation microstructure and visual field loss. Detailed brain imaging shows that the asymmetric visual field deficits in patients with PCA reflect the pattern of degeneration of both white and gray matter in the occipital lobe. Understanding the nature of both visual field deficits and the neurodegenerative brain changes in PCA may improve diagnosis and understanding of this disease.
Rueckriegel, Stefan M., E-mail: email@example.com [Pediatric Neurooncology Program, Department of Pediatric Oncology and Hematology, Charite-Universitaetsmedizin Berlin, Berlin (Germany); Driever, Pablo Hernaiz [Pediatric Neurooncology Program, Department of Pediatric Oncology and Hematology, Charite-Universitaetsmedizin Berlin, Berlin (Germany); Bruhn, Harald [Department of Radiology, Charite-Universitaetsmedizin Berlin, Berlin (Germany); Department of Radiology, Klinikum der Friedrich-Schiller-Universitaet, Erlanger (Germany)
Purpose: Therapy and tumor-related effects such as hypoperfusion, internal hydrocephalus, chemotherapy, and irradiation lead to significant motor and cognitive sequelae in pediatric posterior fossa tumor survivors. A distinct proportion of those factors related to the resulting late effects is hitherto poorly understood. This study aimed at separating the effects of neurotoxic factors on central nervous system metabolism by using H-1 MR spectroscopy to quantify cerebral metabolite concentrations in these patients in comparison to those in age-matched healthy peers. Methods and Materials: Fifteen patients with World Health Organization (WHO) I pilocytic astrocytoma (PA) treated by resection only, 24 patients with WHO IV medulloblastoma (MB), who additionally received chemotherapy and craniospinal irradiation, and 43 healthy peers were investigated using single-volume H-1 MR spectroscopy of parietal white matter and gray matter. Results: Concentrations of N-acetylaspartate (NAA) were significantly decreased in white matter (p < 0.0001) and gray matter (p < 0.0001) of MB patients and in gray matter (p = 0.005) of PA patients, compared to healthy peers. Decreased creatine concentrations in parietal gray matter correlated significantly with older age at diagnosis in both patient groups (MB patients, p = 0.009, r = 0.52; PA patients, p = 0.006, r = 0.7). Longer time periods since diagnosis were associated with lower NAA levels in white matter of PA patients (p = 0.008, r = 0.66). Conclusions: Differently decreased NAA concentrations were observed in both PA and MB groups of posterior fossa tumor patients. We conclude that this reflects a disturbance of the neurometabolic steady state of normal-appearing brain tissue due to the tumor itself and to the impact of surgery in both patient groups. Further incremental decreases of metabolite concentrations in MB patients may point to additional harm caused by irradiation and chemotherapy. The stronger decrease of NAA in MB
Pisoni, Alberto; Turi, Zsolt; Raithel, Almuth; Ambrus, Géza Gergely; Alekseichuk, Ivan; Schacht, Annekathrin; Paulus, Walter; Antal, Andrea
There is emerging evidence from imaging studies that parietal and temporal cortices act together to achieve successful recognition of declarative information; nevertheless, the precise role of these regions remains elusive. To evaluate the role of these brain areas in declarative memory retrieval, we applied bilateral tDCS, with anode over the left and cathode over the right parietal or temporal cortices separately, during the recognition phase of a verbal learning paradigm using a balanced old-new decision task. In a parallel group design, we tested three different groups of healthy adults, matched for demographic and neurocognitive status: two groups received bilateral active stimulation of either the parietal or the temporal cortex, while a third group received sham stimulation. Accuracy, discriminability index (d') and reaction times of recognition memory performance were measurements of interest. The d' sensitivity index and accuracy percentage improved in both active stimulation groups, as compared with the sham one, while reaction times remained unaffected. Moreover, the analysis of accuracy revealed a different effect of tDCS for old and new item recognition. While the temporal group showed enhanced performance for old item recognition, the parietal group was better at correctly recognising new ones. Our results support an active role of both of these areas in memory retrieval, possibly underpinning different stages of the recognition process.
Full Text Available Apathy is a common symptom in patients with amnestic mild cognitive impairment (aMCI and is associated with an increased risk of progression to Alzheimer’s disease (AD. The neural substrates underlying apathy in aMCI may involve multiple brain regions, including the anterior cingulate cortex and the temporo-parietal region. Here we investigated neurometabolites in brain regions that may underlie apathy in aMCI patients using proton magnetic resonance spectroscopy (1H-MRS. Twenty-eight aMCI patients with varying degrees of apathy and 20 matched controls underwent 1H-MRS. Spectra were acquired from single voxels in the posterior cingulate cortex (PCC, dorsal anterior cingulate cortex (DACC, right dorsolateral prefrontal cortex (DLPFC, and right temporo-parietal cortex (TPC. Apathy was measured with the Apathy Evaluation Scale (AES. Spearman partial correlations between metabolite concentrations in each region and severity of apathy were determined. Additionally, analyses of covariance (ANCOVA were performed to determine whether metabolite changes differed between patients with or without clinically-diagnosed apathy. The degree of apathy was found to be negatively correlated with choline and myo-inositol (mI in the TPC. Additional exploratory analyses suggested that N-acetylaspartate (NAA/mI ratio was reduced in aMCI without clinical apathy but not in aMCI with clinical apathy. In the DACC, glutamate and glutamine (Glx levels tended to be higher in the aMCI with apathy group compared to controls and reduced in association with depression scores. In conclusion, apathy in aMCI patients was associated with neurometabolite changes indicative of altered membranal integrity and glial function in the right TPC. Findings also indicated that in a clinically-diagnosed aMCI cohort, apathy symptoms may be suggestive of neural changes that are distinct from aMCI without apathy.
Tumati, Shankar; Opmeer, Esther M; Marsman, Jan-Bernard C; Martens, Sander; Reesink, Fransje E; De Deyn, Peter P; Aleman, André
Apathy is a common symptom in patients with amnestic mild cognitive impairment (aMCI) and is associated with an increased risk of progression to Alzheimer's disease (AD). The neural substrates underlying apathy in aMCI may involve multiple brain regions, including the anterior cingulate cortex and the temporo-parietal region. Here we investigated neurometabolites in brain regions that may underlie apathy in aMCI patients using proton magnetic resonance spectroscopy ( 1 H-MRS). Twenty-eight aMCI patients with varying degrees of apathy and 20 matched controls underwent 1 H-MRS. Spectra were acquired from single voxels in the posterior cingulate cortex (PCC), dorsal anterior cingulate cortex (DACC), right dorsolateral prefrontal cortex (DLPFC), and right temporo-parietal cortex (TPC). Apathy was measured with the Apathy Evaluation Scale (AES). Spearman partial correlations between metabolite concentrations in each region and severity of apathy were determined. Additionally, analyses of covariance (ANCOVA) were performed to determine whether metabolite changes differed between patients with or without clinically-diagnosed apathy. The degree of apathy was found to be negatively correlated with choline and myo-inositol (mI) in the TPC. Additional exploratory analyses suggested that N-acetylaspartate (NAA)/mI ratio was reduced in aMCI without clinical apathy but not in aMCI with clinical apathy. In the DACC, glutamate and glutamine (Glx) levels tended to be higher in the aMCI with apathy group compared to controls and reduced in association with depression scores. In conclusion, apathy in aMCI patients was associated with neurometabolite changes indicative of altered membranal integrity and glial function in the right TPC. Findings also indicated that in a clinically-diagnosed aMCI cohort, apathy symptoms may be suggestive of neural changes that are distinct from aMCI without apathy.
Bozkurt, Y.; Battal, B.; Ozcan, E.; Kocaoglu, M.
Full text: Background: The cerebral cortex develops in three overlapping stages: cell proliferation, neuronal migration, and cortical organization. Lissencephaly (smooth brain) is a severe malformation of the cerebral cortex that results from impaired neuronal migration. Polymicrogyria is a disorder of late migration or cortical organization, and supposed to reflect a disruption of normal neuronal migration with subsequent disordered cortical organization. A combination of cobblestone lissencephaly and polymicrogyria is very rare in the same patient's brain. Objective: To present clinical and 3T magnetic resonance (MR) imaging findings of a 17-year-old male with bilateral fronto-parietal polimicrogyria accompanied by cobblestone lissencaphaly. Materials and methods: A 17-year-old male who had seizures and involuntary muscular spasm from birth, was referred to our Hospital. The patient was evaluated by a complete history, physical examination, a laboratory work-up, and cranial MR examination for evaluate the central nervous system. Results: A sharp wave paroxysm in the left temporal area was observed in the electroencephalogram (EEG). The neurological examination of our patient was normal. A slight increase have seen in the aspartate aminotransferase (SGOT) levels. The other biochemical tests were found to be normal. Cranial MR imaging showed an irregular nodular cortex with hypomyelination of the white matter at the lateral and posterior part of the right occipital lobe. We also observed the changes compatible with polymicrogyria in a large area of the medial parts of the bilateral temporal and parietal lobes. Conclusion: The role of radiological modalities for diagnosis of cortical formation disorders are very important. MR imaging are fairly useful for evaluation of these anomalies
Murthy, U K; Levine, R A
The morphological response of rabbit parietal cells to aspirin was evaluated by grading several ultra-structural features including the extent of the tubulovesicular system, intracellular secretory canaliculi, and microvilli. After exposure of isolated parietal cells and gastric glands to aspirin or histamine, there was an approximately twofold increase in the ratio of secretory to nonsecretory parietal cells, and depletion of extracellular Ca2+ abolished the aspirin-induced morphological changes. Morphometry in parietal cells showed that aspirin induced a sixfold increase in secretory canalicular membrane elaboration. Aspirin potentiated histamine-induced parietal cell respiration and aminopyrine uptake ratio but did not increase basal respiration or aminopyrine uptake, suggesting an apparent dissociation from aspirin-induced morphological changes.
Zhao Xiaohu; Wang Peijun; Dong Ningxin; Li Chunbo; Wu Wenyuan; Hu Zhenghui; Tang Xiaowei
Objective: We used blood oxygenation level dependent-functional MR imaging (BOLD- fMRI) to explore the characteristics of deactivation patterns in patients with anxiety disorders and the underlying neural mechanism of this disease. Methods: Ten patients and ten healthy controls participated the experiments. All subjects performed the trait portion of the State-Trait anxiety Inventory (STAI-T) prior to the fMRI scans. The subjects underwent noninvasive functional magnetic resonance imaging while listening actively to emotionally neutral words alternating with no words (experiment 1) and threat related-words alternating with emotionally neutral words (experiment2). During fMRI scanning, subjects were instructed to closely listen to each stimuli word and to silently make a judgment of the word's valence. Data were analyzed with statistical parametric mapping (SPM 99). Individual and group analysis were conducted. Results: Mean STAI-T score was significantly higher for patients group than that of controls (58 ± 8 for patients group and 33 ± 5 for controls, t=8.3, P<0.01). Our fMRI data revealed sets of deactivation brain regions in Experiment for patients and healthy controls, however, the deactivation can be found in experiment 2 only for patients. Interestingly, all the observed deactivation patterns were similar. The related areas compromise medial prefrontal cortex(BA 10, BA 24/32), posterior cingulate (BA 31/30) and Bilateral inferior parietal cortex (MPFC) (BA 39/40), which nearly overlapping with the organized default model network. Further more, the mean t values in the MPFC area (BA 24/32) was significantly higher for control group than that of patient (5.1 controls and 4.2 for patients, t=4.8, P=0.006), conversely, the mean t values in the posterior cingulate cortex(PCC) area was significantly higher for patients l than that of controls (4.9 controls and 5.8 for patients, t=2.4, P=0.026). Conclusion: Our observations suggest that the default model network
Andres, Michael; Pelgrims, Barbara; Olivier, Etienne
Neuropsychological studies showed that manipulatory and semantic knowledge can be independently impaired in patients with upper-limb apraxia, leading to different tool use disorders. The present study aimed to dissociate the brain regions involved in judging the hand configuration or the context associated to tool use. We focussed on the left supramarginalis gyrus (SMG) and left middle temporal gyrus (MTG), whose activation, as evidenced by functional magnetic resonance imaging (fMRI) studies, suggests that they may play a critical role in tool use. The distinctive location of SMG in the dorsal visual stream led us to postulate that this parietal region could play a role in processing incoming information about tools to shape hand posture. In contrast, we hypothesized that MTG, because of its interconnections with several cortical areas involved in semantic memory, could contribute to retrieving semantic information necessary to create a contextual representation of tool use. To test these hypotheses, we used neuronavigated transcranial magnetic stimulation (TMS) to interfere transiently with the function of either left SMG or left MTG in healthy participants performing judgement tasks about either hand configuration or context of tool use. We found that SMG virtual lesions impaired hand configuration but not contextual judgements, whereas MTG lesions selectively interfered with judgements about the context of tool use while leaving hand configuration judgements unaffected. This double dissociation demonstrates that the ability to infer a context of use or a hand posture from tool perception relies on distinct processes, performed in the temporal and parietal regions. The present findings suggest that tool use disorders caused by SMG lesions will be characterized by difficulties in selecting the appropriate hand posture for tool use, whereas MTG lesions will yield difficulties in using tools in the appropriate context. Copyright © 2012. Published by Elsevier Ltd.
Conci, Markus; Groß, Julia; Keller, Ingo; Müller, Hermann J; Finke, Kathrin
Patients with unilateral, parietal brain damage frequently show visual extinction, which manifests in a failure to identify contralesional stimuli when presented simultaneously with other, ipsilesional stimuli (but full awareness for single stimulus presentations). Extinction reflects an impairment of spatial selective attention, leaving basic preattentive processing unaffected. For instance, access to bilaterally grouped objects is usually spared in extinction, suggesting that grouping occurs at a stage preceding (in the patients: abnormally biased) spatial-attentional selection. Here, we reinvestigated this notion by comparing (largely between participants, but also within a single-case participant) conditions with objects that varied in their dominant direction of grouping: from the attended to the non-attended hemifield (data from Conci et al., 2009) versus from the non-attended to the attended hemifield (new data). We observe complete absence of extinction when shape completion extended from the attended hemifield. By contrast, extinction was not diminished when object groupings propagate from the unattended hemifield. Moreover, we found the individual severity of the attentional impairment (assessed by a standard "inattention" test) to be directly related to the degree of completion in the unattended hemifield. This pattern indicates that grouping can overcome visual extinction only when object integration departs from the attended visual field, implying, contrary to many previous accounts, that attention is crucial for grouping to be initiated. Copyright © 2018 Elsevier Ltd. All rights reserved.
Miesen, Laura; Steenbergen, Eric; Smeets, Bart
In normal glomeruli, parietal epithelial cells (PECs) line the inside of Bowman's capsule and form an inconspicuous sheet of flat epithelial cells in continuity with the proximal tubular epithelial cells (PTECs) at the urinary pole and with the podocytes at the vascular pole. PECs, PTECs and podocytes have a common mesenchymal origin and are the result of divergent differentiation during embryogenesis. Podocytes and PTECs are highly differentiated cells with well-established functions pertaining to the maintenance of the filtration barrier and transport, respectively. For PECs, no specific function other than a structural one has been known until recently. Possible important functions for PECs in the fate of the glomerulus in glomerular disease have now become apparent: (1) PECs may be involved in the replacement of lost podocytes; (2) PECs form the basis of extracapillary proliferative lesions and subsequent sclerosis in glomerular disease. In addition to the acknowledgement that PECs are crucial in glomerular disease, knowledge has been gained regarding the molecular processes driving the phenotypic changes and behavior of PECs. Understanding these molecular processes is important for the development of specific therapeutic approaches aimed at either stimulation of the regenerative function of PECs or inhibition of the pro-sclerotic action of PECs. In this review, we discuss recent advances pertaining to the role of PECs in glomerular regeneration and disease and address the major molecular processes involved.
Berger, Katja; Schulte, Kevin; Boor, Peter; Kuppe, Christoph; van Kuppevelt, Toin H; Floege, Jürgen; Smeets, Bart; Moeller, Marcus J
Previously, we showed that some podocytes in juvenile mice are recruited from cells lining Bowman's capsule, suggesting that parietal epithelial cells (PECs) are a progenitor cell population for podocytes. To investigate whether PECs also replenish podocytes in adult mice, PECs were genetically labeled in an irreversible fashion in 5-week-old mice. No significant increase in labeled podocytes was observed, even after 18 months. To accelerate a potential regenerative mechanism, progressive glomerular hypertrophy was induced by progressive partial nephrectomies. Again, no significant podocyte replenishment was observed. Rather, labeled PECs exclusively invaded segments of the tuft affected by glomerulosclerosis, consistent with our previous findings. We next reassessed PEC recruitment in juvenile mice using a different reporter mouse and confirmed significant recruitment of labeled PECs onto the glomerular tuft. Moreover, some labeled cells on Bowman's capsule expressed podocyte markers, and cells on Bowman's capsule were also directly labeled in juvenile podocyte-specific Pod-rtTA transgenic mice. In 6-week-old mice, however, cells on Bowman's capsule no longer expressed podocyte-specific markers. Similarly, in human kidneys, some cells on Bowman's capsule expressed the podocyte marker synaptopodin from 2 weeks to 2 years of age but not at 7 years of age. In summary, podocyte regeneration from PECs could not be detected in aging mice or models of glomerular hypertrophy. We propose that a small fraction of committed podocytes reside on Bowman's capsule close to the vascular stalk and are recruited onto the glomerular tuft during infancy to adolescence in mice and humans.
Full Text Available Since the Korean language has two distinct writing systems, phonogram (Hangul and ideogram (Hanja: Chinese characters, alexia can present with dissociative disturbances in reading between the two systems. A 74-year-old right-handed man presented with a prominent reading impairment in Hangul with agraphia of both Hangul and Hanja after a left posterior occipital- parietal lesion. He could not recognize single syllable words and nonwords in Hangul, and visual errors were predominant in both Hanja reading and the Korean Boston Naming Test. In addition, he had difficulties in visuoperceptual tests including Judgment of Line Orientation, Hierarchical Navon figures, and complex picture scanning. These findings are consistent with the hypothesis that Hangul reading impairment results from a general visual perceptual deficit. However, this assumption cannot explain why performance on visually complex Hanja was better than performance on visually simple Hanja in our patient. In addition, the patient did not demonstrate higher accuracy on Hanja characters with fewer strokes than on words with more strokes. Thus, we speculate that the left posterior occipital area may be specialized for Hangul letter identification in this patient. This case demonstrates that Hangul-Hanja reading dissociation impairment can occur after occipital-parietal lesions.
Mário S. Cademartori
Full Text Available São relatados 6 casos de hematomas sub-tentorias (um de hematoma subdural crônico, quatro de hematomas intra-cerebelares, um de hematoma extra-dural. Salientando a pequena freqüência dos hematomas da fossa craniana posterior, o autor mostra a necessidade de vários exames complementares para o diagnóstico exato, indispensável para a aplicação de terapêutica cirúrgica adequada.
Jorge Félix Companioni Rosildo
Full Text Available Congenital encephalocele is a neural tube defect characterized by a sac-like protrusion of the brain, meninges, and other intracranial structures through the skull, which is caused by an embryonic development abnormality. The most common location is at the occipital bone, and its incidence varies according to different world regions. We report a case of an 1-month and 7-day-old male child with a huge interparietal-posterior fontanel meningohydroencephalocele, a rare occurrence. Physical examination and volumetric computed tomography were diagnostic. The encephalocele was surgically resected. Intradural and extradural approaches were performed; the bone defect was not primarily closed. Two days after surgery, the patient developed hydrocephaly requiring ventriculoperitoneal shunting. The surgical treatment of the meningohydroencephalocele of the interparietal-posterior fontanel may be accompanied by technical challenges and followed by complications due to the presence of large blood vessels under the overlying skin. In these cases, huge sacs herniate through large bone defects including meninges, brain, and blood vessels. The latter present communication with the superior sagittal sinus and ventricular system. A favorable surgical outcome generally follows an accurate strategy taking into account individual features of the lesion.
Albertine, K H; Wiener-Kronish, J P; Staub, N C
We studied the parietal pleura of six sheep to obtain information on pleural structure, blood supply, and lymphatic drainage. In the strict sense, the parietal pleura is composed of a single layer of mesothelial cells and a uniform layer of loose, irregular connective tissue (about 23 micron in width) subjacent to the mesothelial cells. The parietal pleural blood vessels are 10-15 micron from the pleural space. Tracer substances put in the pleural space are removed at specific locations. Colloidal carbon and chick red blood cells are cleared by the parietal pleural lymphatics located over the intercostal spaces at the caudal end of the thoracic wall and over the lateral sides of the pericardial sac. In these areas the mesothelial cells have specialized openings, the stomata, that directly communicate with the underlying lymphatic lacunae. Cells and particulate matter in the pleural space are cleared only by the parietal pleural lymphatics. Compared to the visceral pleura, we believe the thinness of the parietal pleura, the closeness of its blood vessels to the pleural space, and its specialized lymphatic clearance pathways, together indicate that the parietal pleura plays a major role in pleural liquid and protein dynamics in sheep.
Schulte, Kevin; Berger, Katja; Boor, Peter; Jirak, Peggy; Gelman, Irwin H; Arkill, Kenton P; Neal, Christopher R; Kriz, Wilhelm; Floege, Jürgen; Smeets, Bart; Moeller, Marcus J
Parietal podocytes are fully differentiated podocytes lining Bowman's capsule where normally only parietal epithelial cells (PECs) are found. Parietal podocytes form throughout life and are regularly observed in human biopsies, particularly in atubular glomeruli of diseased kidneys; however, the origin of parietal podocytes is unresolved. To assess the capacity of PECs to transdifferentiate into parietal podocytes, we developed and characterized a novel method for creating atubular glomeruli by electrocoagulation of the renal cortex in mice. Electrocoagulation produced multiple atubular glomeruli containing PECs as well as parietal podocytes that projected from the vascular pole and lined Bowman's capsule. Notably, induction of cell death was evident in some PECs. In contrast, Bowman's capsules of control animals and normal glomeruli of electrocoagulated kidneys rarely contained podocytes. PECs and podocytes were traced by inducible and irreversible genetic tagging using triple transgenic mice (PEC- or Pod-rtTA/LC1/R26R). Examination of serial cryosections indicated that visceral podocytes migrated onto Bowman's capsule via the vascular stalk; direct transdifferentiation from PECs to podocytes was not observed. Similar results were obtained in a unilateral ureter obstruction model and in human diseased kidney biopsies, in which overlap of PEC- or podocyte-specific antibody staining indicative of gradual differentiation did not occur. These results suggest that induction of atubular glomeruli leads to ablation of PECs and subsequent migration of visceral podocytes onto Bowman's capsule, rather than transdifferentiation from PECs to parietal podocytes.
Naito, Eiichi; Morita, Tomoyo; Saito, Daisuke N; Ban, Midori; Shimada, Koji; Okamoto, Yuko; Kosaka, Hirotaka; Okazawa, Hidehiko; Asada, Minoru
Functional lateralization can be an indicator of brain maturation. We have consistently shown that, in the adult brain, proprioceptive processing of muscle spindle afferents generating illusory movement of the right hand activates inferior frontoparietal cortical regions in a right-side dominant manner in addition to the cerebrocerebellar motor network. Here we provide novel evidence regarding the development of the right-dominant use of the inferior frontoparietal cortical regions in humans using this task. We studied brain activity using functional magnetic resonance imaging while 60 right-handed blindfolded healthy children (8-11 years), adolescents (12-15 years), and young adults (18-23 years) (20 per group) experienced the illusion. Adult-like right-dominant use of the inferior parietal lobule (IPL) was observed in adolescents, while children used the IPL bilaterally. In contrast, adult-like lateralized cerebrocerebellar motor activation patterns were already observable in children. The right-side dominance progresses during adolescence along with the suppression of the left-sided IPL activity that emerges during childhood. Therefore, the neuronal processing implemented in the adult's right IPL during the proprioceptive illusion task is likely mediated bilaterally during childhood, and then becomes right-lateralized during adolescence at a substantially later time than the lateralized use of the cerebrocerebellar motor system for kinesthetic processing. © The Author 2017. Published by Oxford University Press.
Naito, Eiichi; Morita, Tomoyo; Saito, Daisuke N; Ban, Midori; Shimada, Koji; Okamoto, Yuko; Kosaka, Hirotaka; Okazawa, Hidehiko; Asada, Minoru
Abstract Functional lateralization can be an indicator of brain maturation. We have consistently shown that, in the adult brain, proprioceptive processing of muscle spindle afferents generating illusory movement of the right hand activates inferior frontoparietal cortical regions in a right-side dominant manner in addition to the cerebrocerebellar motor network. Here we provide novel evidence regarding the development of the right-dominant use of the inferior frontoparietal cortical regions in humans using this task. We studied brain activity using functional magnetic resonance imaging while 60 right-handed blindfolded healthy children (8–11 years), adolescents (12–15 years), and young adults (18–23 years) (20 per group) experienced the illusion. Adult-like right-dominant use of the inferior parietal lobule (IPL) was observed in adolescents, while children used the IPL bilaterally. In contrast, adult-like lateralized cerebrocerebellar motor activation patterns were already observable in children. The right-side dominance progresses during adolescence along with the suppression of the left-sided IPL activity that emerges during childhood. Therefore, the neuronal processing implemented in the adult's right IPL during the proprioceptive illusion task is likely mediated bilaterally during childhood, and then becomes right-lateralized during adolescence at a substantially later time than the lateralized use of the cerebrocerebellar motor system for kinesthetic processing. PMID:28968653
Raymond PIERRE Kesner
Full Text Available When several different objects are presented, visual objects are perceived correctly only if their features are identified and then bound together. Illusory-conjunction errors result when an object is correctly identified but is combined incorrectly. The parietal cortex (PPC has been shown repeatedly to play an important role in feature binding. The present study builds on a series of recent studies that have made use of visual search paradigms to elucidate the neural system involved in feature binding. This experiment attempts to define the role the PPC plays in binding the properties of a visual object that varies on the features of color and size in rats. Rats with PPC lesions or control surgery were exposed to three blocks of 20 trials administered over a 1-week period, with each block containing ten-one feature and ten-two feature trials. The target object consisted of one color object (e.g. black and white and one size object (e.g. short and tall. Of the ten one feature trials, five of the trials were tailored specifically for size discrimination and five for color discrimination. In the two-feature condition, the animal was required to locate the targeted object among four objects with two objects differing in size and two objects differing in color. The results showed a significant decrease in learning the task for the PPC lesioned rats compared to controls, especially for the two-feature condition. Based on a subsequent error analysis for color and size, the results showed a significant increase in illusory conjunction errors for the PPC lesioned rats relative to controls for color and relative to color discrimination, suggesting that the PPC may support feature binding as it relates to color. There was an increase in illusory conjunctions errors for both the PPC lesioned and control animals for size, but this appeared to be due to a difficulty with size discrimination.
Berger, Katja; Schulte, Kevin; Boor, Peter; Kuppe, Christoph; van Kuppevelt, Toin H.; Floege, Jürgen; Smeets, Bart
Previously, we showed that some podocytes in juvenile mice are recruited from cells lining Bowman’s capsule, suggesting that parietal epithelial cells (PECs) are a progenitor cell population for podocytes. To investigate whether PECs also replenish podocytes in adult mice, PECs were genetically labeled in an irreversible fashion in 5-week-old mice. No significant increase in labeled podocytes was observed, even after 18 months. To accelerate a potential regenerative mechanism, progressive glomerular hypertrophy was induced by progressive partial nephrectomies. Again, no significant podocyte replenishment was observed. Rather, labeled PECs exclusively invaded segments of the tuft affected by glomerulosclerosis, consistent with our previous findings. We next reassessed PEC recruitment in juvenile mice using a different reporter mouse and confirmed significant recruitment of labeled PECs onto the glomerular tuft. Moreover, some labeled cells on Bowman’s capsule expressed podocyte markers, and cells on Bowman’s capsule were also directly labeled in juvenile podocyte-specific Pod-rtTA transgenic mice. In 6-week-old mice, however, cells on Bowman’s capsule no longer expressed podocyte-specific markers. Similarly, in human kidneys, some cells on Bowman’s capsule expressed the podocyte marker synaptopodin from 2 weeks to 2 years of age but not at 7 years of age. In summary, podocyte regeneration from PECs could not be detected in aging mice or models of glomerular hypertrophy. We propose that a small fraction of committed podocytes reside on Bowman’s capsule close to the vascular stalk and are recruited onto the glomerular tuft during infancy to adolescence in mice and humans. PMID:24408873
The posterior tibial muscle is the main functional support of the plantar arch its dysfunction is the main cause of acquired flat foot. This is a 32 year old patient who consults for progressive pain of the inside of the ankle and right foot with a considerable decrease in its sporting and professional activity. Examination reveals a ...
Sprain of the ankle is undoubtedly a common injury during athletic activity, and the sprain can be also associated with fracture of the ankle. Isolated posterior malleolus fracture is a very rare condition, which is usually missed. Here, we are presenting a 37 years old female patient, who suffered injury secondary pressing on ...
Yokoi, Katsunori; Ando, Tetsuo; Kawakami, Osamu
This report presents a case of a 71-year-old woman with Fisher syndrome who had posterior reversible encephalopathy syndrome (PRES) before the initiation of intravenous immunoglobulin (IVIg) treatment. She had symptoms of common cold 2 weeks before the onset of PRES. On the day of the onset, she began to stagger while walking. On day 2, she developed hypertension, vision impairment, and limb weakness and was admitted to the hospital. On day 3, she was provided steroid pulse therapy. On day 4, she developed convulsions and right imperfection single paralysis and was transferred to the our hospital. During the transfer, the patient was conscious. Her blood pressure was high at 198/107 mmHg. She had mild weakness in her limbs and face, light perception in both eyes, dilation of both pupils, total external ophthalmoplegia, no tendon reflexes, and limb and trunk ataxia. We diagnosed PRES because of the high signal intensities observed on T 2 -weighted MRI on both sides of the parietal and occipital lobes. We also diagnosed Fisher syndrome because of a positive anti-GQ1b immunoglobulin G antibody test and albuminocytologic dissociation in the cerebrospinal fluid. PRES showed prompt improvement with antihypertensive therapy, whereas Fisher syndrome slowly improved over a course of 2 months. This case is the first report of PRES without IVIg suggesting that Fisher syndrome induces hypertension and causes PRES.
Terhune, Devin Blair; Cardeña, Etzel; Lindgren, Magnus
Spontaneous dissociative alterations in awareness and perception among highly suggestible individuals following a hypnotic induction may result from disruptions in the functional coordination of the frontal-parietal network. We recorded EEG and self-reported state dissociation in control and hypnosis conditions in two sessions with low and highly suggestible participants. Highly suggestible participants reliably experienced greater state dissociation and exhibited lower frontal-parietal phase synchrony in the alpha2 frequency band during hypnosis than low suggestible participants. These findings suggest that highly suggestible individuals exhibit a disruption of the frontal-parietal network that is only observable following a hypnotic induction. Copyright © 2011 Society for Psychophysiological Research.
El Filali, Z; de Boer, P A C M; Pieneman, A W; de Lange, R P J; Jansen, R F; Ter Maat, A; van der Schors, R C; Li, K W; van Straalen, N M; Koene, J M
Male copulation is a complex behavior that requires coordinated communication between the nervous system and the peripheral reproductive organs involved in mating. In hermaphroditic animals, such as the freshwater snail Lymnaea stagnalis, this complexity increases since the animal can behave both as male and female. The performance of the sexual role as a male is coordinated via a neuronal communication regulated by many peptidergic neurons, clustered in the cerebral and pedal ganglia and dispersed in the pleural and parietal ganglia. By combining single-cell matrix-assisted laser mass spectrometry with retrograde staining and electrophysiology, we analyzed neuropeptide expression of single neurons of the right parietal ganglion and their axonal projections into the penial nerve. Based on the neuropeptide profile of these neurons, we were able to reconstruct a chemical map of the right parietal ganglion revealing a striking correlation with the earlier electrophysiological and neuroanatomical studies. Neurons can be divided into two main groups: (i) neurons that express heptapeptides and (ii) neurons that do not. The neuronal projection of the different neurons into the penial nerve reveals a pattern where (spontaneous) activity is related to branching pattern. This heterogeneity in both neurochemical anatomy and branching pattern of the parietal neurons reflects the complexity of the peptidergic neurotransmission involved in the regulation of male mating behavior in this simultaneous hermaphrodite.
Santangelo, Valerio; Di Francesco, Simona Arianna; Mastroberardino, Serena; Macaluso, Emiliano
The Brief presentation of a complex scene entails that only a few objects can be selected, processed indepth, and stored in memory. Both low-level sensory salience and high-level context-related factors (e.g., the conceptual match/mismatch between objects and scene context) contribute to this selection process, but how the interplay between these factors affects memory encoding is largely unexplored. Here, during fMRI we presented participants with pictures of everyday scenes. After a short retention interval, participants judged the position of a target object extracted from the initial scene. The target object could be either congruent or incongruent with the context of the scene, and could be located in a region of the image with maximal or minimal salience. Behaviourally, we found a reduced impact of saliency on visuospatial working memory performance when the target was out-of-context. Encoding-related fMRI results showed that context-congruent targets activated dorsoparietal regions, while context-incongruent targets de-activated the ventroparietal cortex. Saliency modulated activity both in dorsal and ventral regions, with larger context-related effects for salient targets. These findings demonstrate the joint contribution of knowledge-based and saliency-driven attention for memory encoding, highlighting a dissociation between dorsal and ventral parietal regions. © 2015 Wiley Periodicals, Inc.
Danner, Simon M; Hofstoetter, Ursula S; Ladenbauer, Josef; Rattay, Frank; Minassian, Karen
Stimulation of different spinal cord segments in humans is a widely developed clinical practice for modification of pain, altered sensation, and movement. The human lumbar cord has become a target for modification of motor control by epidural and, more recently, by transcutaneous spinal cord stimulation. Posterior columns of the lumbar spinal cord represent a vertical system of axons and when activated can add other inputs to the motor control of the spinal cord than stimulated posterior roots. We used a detailed three-dimensional volume conductor model of the torso and the McIntyre-Richard-Grill axon model to calculate the thresholds of axons within the posterior columns in response to transcutaneous lumbar spinal cord stimulation. Superficially located large-diameter posterior column fibers with multiple collaterals have a threshold of 45.4 V, three times higher than posterior root fibers (14.1 V). With the stimulation strength needed to activate posterior column axons, posterior root fibers of large and small diameters as well as anterior root fibers are coactivated. The reported results inform on these threshold differences, when stimulation is applied to the posterior structures of the lumbar cord at intensities above the threshold of large-diameter posterior root fibers. © 2011, Copyright the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.
Ramantani, Georgia; Stathi, Angeliki; Brandt, Armin; Strobl, Karl; Schubert-Bast, Susanne; Wiegand, Gert; Korinthenberg, Rudolf; van Velthoven, Vera; Zentner, Josef; Schulze-Bonhage, Andreas; Bast, Thomas
We aimed to investigate the long-term seizure outcome of children and adolescents who were undergoing epilepsy surgery in the parietooccipital cortex and determine their predictive factors. We retrospectively analyzed the data of 50 consecutive patients aged 11.1 (mean) ± 5.1 (standard deviation) years at surgery. All patients but one had a magnetic resonance imaging (MRI)-visible lesion. Resections were parietal in 40%, occipital in 32%, and parietooccipital in 28% cases; 24% patients additionally underwent a resection of the posterior border of the temporal lobe. Etiology included focal cortical dysplasia in 44%, benign tumors (dysembryoplastic neuroepithelial tumor, ganglioglioma, angiocentric glioma, and pilocystic astrocytoma) in 32%, peri- or postnatal ischemic lesions in 16%, and tuberous sclerosis in 8% cases. At last follow-up (mean 8 years, range 1.5-18 years), 60% patients remained seizure-free (Engel class I): 30% had discontinued and 20% had reduced antiepileptic drugs. Most seizure recurrences (71%) occurred within the first 6 months, and only three patients presented with seizures ≥2 years after surgery. Independent predictors of seizure recurrence included left-sided as well as parietal epileptogenic zones and resections. Longer epilepsy duration to surgery was identified as the only modifiable independent predictor of seizure recurrence. Our study demonstrates that posterior cortex epilepsy surgery is highly effective in terms of lasting seizure control and antiepileptic drug cessation in selected pediatric candidates. Most importantly, our data supports the early consideration of surgical intervention in children and adolescents with refractory posterior cortex epilepsy. Wiley Periodicals, Inc. © 2017 International League Against Epilepsy.
Schulz, Kurt P; Li, Xiaobo; Clerkin, Suzanne M; Fan, Jin; Berwid, Olga G; Newcorn, Jeffrey H; Halperin, Jeffrey M
The protracted and highly variable development of prefrontal cortex regions that support cognitive control has been purported to shape the adult outcome of attention-deficit/hyperactivity disorder (ADHD). This neurodevelopmental model was tested in a prospectively followed sample of 27 adult probands who were diagnosed with ADHD in childhood and 28 carefully matched comparison subjects aged 21-28 years. Probands were classified with persistent ADHD or remitted ADHD. Behavioral and neural responses to the Stimulus and Response Conflict Task (SRCT) performed during functional magnetic resonance imaging (fMRI) were compared in probands and comparison subjects and in probands with persistent and remitted ADHD. Response speed and accuracy for stimulus, response, and combined conflicts did not differ across groups. Orbitofrontal, inferior frontal and parietal activation was lower in probands than comparison subjects, but only for combined conflicts, when demand for cognitive control was highest. Reduced activation for combined conflicts in probands was almost wholly attributable to the persistence of ADHD; orbitofrontal, inferior frontal, anterior cingulate and parietal activation was lower in probands with persistent ADHD than both probands with remitted ADHD and comparison subjects, but did not differ between probands with remitted ADHD and comparison subjects. These data provide the first evidence that prefrontal and parietal activation during cognitive control parallels the adult outcome of ADHD diagnosed in childhood, with persistence of symptoms linked to reduced activation and symptom recovery associated with activation indistinguishable from adults with no history of ADHD. Copyright © 2017 Elsevier Ltd. All rights reserved.
O'Connor, Akira R.; Han, Sanghoon; Dobbins, Ian G.
Functional neuroimaging studies of episodic recognition demonstrate an increased lateral parietal response for studied versus new materials, often termed a retrieval success effect. Using a novel memory analog of attentional cueing, we manipulated the correspondence between anticipated and actual recognition evidence by presenting valid or invalid anticipatory cues (e. g., "likely old") before recognition judgments. Although a superior parietal region demonstrated the retrieval success patter...
Thomsen, Rasmus Heje; Zakarian, Kristine; Hansen, Per Boye
moderate renal impairment (eGFR > 30 ml/min.) and a normal blood pressure. PRES was confirmed by MRI, which showed oedema of the occipital, parietal and frontal lobes. A control MRI after four weeks showed full remission. To our knowledge this is the first published case of R-ICE causing PRES....
PRES is generally symmetrical, often in the occipital and parietal lobes, and is typically characterized by vasogenic edema in the subcortical white matter. This study involves a 38‑year‑old female patient who had hypertension, used immunosuppressive drugs and was also found to have nephropathy. After 3 months of ...
Full Text Available Boosting memory with transcranial direct current stimulation (tDCS seems to be an elegant way to optimize learning. Here we tested whether tDCS to the left dorsolateral prefrontal cortex or to the left posterior parietal cortex would boost recognition memory in general and/or particularly for action phrases enacted at study. During study, 48 young adults either read or enacted simple action phrases. Memory for the action phrases was assessed after a retention interval of 45 min and again after 7-days to investigate the long-term consequences of brain stimulation. The results showed a robust enactment effect in both test sessions. Moreover, the decrease in performance was more pronounced for reading than for enacting the phrases at study. However, tDCS did not reveal any effect on subsequent recognition memory performance. We conclude that memory benefits of tDCS are not easily replicated. In contrast, enactment at study reliably boosts subsequent memory.
Crescentini, Cristiano; Aglioti, Salvatore M; Fabbro, Franco; Urgesi, Cosimo
Religiousness and spirituality (RS) are two ubiquitous aspects of human experience typically considered impervious to scientific investigation. Nevertheless, associations between RS and frontoparietal neural activity have been recently reported. However, much less is known about whether such activity is causally involved in modulating RS or just epiphenomenal to them. Here we combined two-pulse (10 Hz) Transcranial Magnetic Stimulation (TMS) with a novel, ad-hoc developed RS-related, Implicit Association Test (IAT) to investigate whether implicit RS representations, although supposedly rather stable, can be rapidly modified by a virtual lesion of inferior parietal lobe (IPL) and dorsolateral prefrontal cortex (DLPFC). A self-esteem (SE) IAT, focused on self-concepts nonrelated to RS representations, was developed as control. A specific increase of RS followed inhibition of IPL demonstrating its causative role in inducing fast plastic changes of religiousness/spirituality. In contrast, DLPFC inhibition had more widespread effects probably reflecting a general role in the acquisition or maintenance of task-rules or in controlling the expression of self-related representations not specific to RS. Copyright © 2014 Elsevier Ltd. All rights reserved.
Agnoli, Sergio; Zanon, Marco; Mastria, Serena; Avenanti, Alessio; Corazza, Giovanni Emanuele
The present article describes an innovative neurofeedback training (NFT) procedure aimed at increasing creative cognition through the enhancement of specific brain activities previously associated with divergent thinking. We designed and tested two NFT protocols based on training alpha and beta EEG oscillations selectively measured over the right parietal region. A total of 80 participants were involved, 40 in the alpha NFT protocol and 40 in the beta NFT protocol. The NFT loop was closed on a video stream that would advance only when oscillation power exceeded a normalized threshold. The total duration of the protocol was two hours in a single day, hence its classification as rapid. Changes in ideational fluency and originality, measured with a divergent thinking task, were compared between participants receiving real video feedback and participants receiving sham feedback. We controlled for individual differences in creative achievement level. Results showed that the protocols were effective at enhancing alpha and beta activities in the targeted area. Differences between the two protocols emerged in their effectiveness at promoting divergent thinking. While no significant changes in originality resulted from the rapid alpha NFT, increases in both originality and fluency emerged as a consequence of the rapid beta NFT. These results were particularly evident in participants starting with a low creative achievement level. Possible interpretations and future directions are proposed and discussed. Copyright © 2018 Elsevier Ltd. All rights reserved.
Rizzo, Paola; Novelli, Rubina; Rota, Cinzia; Gagliardini, Elena; Ruggiero, Barbara; Rottoli, Daniela; Benigni, Ariela; Remuzzi, Giuseppe
Crescentic glomerulonephritis (GN) is a devastating disease with rapidly progressive deterioration in kidney function, which, histologically, manifests as crescent formation in most glomeruli. We previously found that crescents derive from the aberrant proliferation and migration of parietal epithelial cells (PECs)/progenitor cells, and that the angiotensin (ang) II/ang II type-1 (AT 1 ) receptor pathway may participate, together with the stromal cell-derived factor-1 (SDF-1)/C-X-C chemokine receptor 4 axis, in the development of those lesions. Herein, we elucidated sequential events and cellular and molecular interactions occurring during crescentic lesion onset and evolution. By analyzing kidney biopsy specimens of patients with extracapillary GN, divided according to the grade of glomerular lesions, we found that the accumulation of macrophages expressing matrix metalloproteinase-12 started manifesting in glomeruli affected by early-stage lesions, whereas AT 1 receptor expression could not be detected. In glomeruli with advanced lesions, AT 1 receptor expression increased markedly, and the up-regulation of SDF-1, and its receptor C-X-C chemokine receptor 7, was documented on podocytes and PECs, respectively. In vitro studies were instrumental to demonstrating the role of ang II in inducing podocyte SDF-1 production, which ultimately activates PECs. The present findings support the possibility that angiotensin-converting enzyme inhibitor treatment might limit PEC activation and reduce the frequency and extension of crescents in extracapillary GN. Copyright © 2017 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.
Full Text Available Visuospatial construction, traditionally viewed as a putative parietal function, also requires sustained attention, planning, organization strategies and error correction, and hence frontal lobe mediation. The relative contributions of the frontal and parietal lobes are poorly understood. To examine the contributions of parietal, frontal lobes, as well as right and left cerebral hemispheres to visuospatial construction. The Stick Construction Test for two-dimensional construction and the Block Construction Test for three-dimensional construction were administered pre-surgically to patients with lesions in the parietal lobe (n =9 and the frontal lobe (n=11, along with normal control subjects (n =20 matched to the patients on age (+/- 3 years, gender, education (+/- 3 years and handedness. The patients were significantly slower than the controls on both two-dimensional and three-dimensional tests. Patients with parietal lesions were slower than those with frontal lesions on the test of three-dimensional construction. Within each lobe patients with right and left sided lesions did not differ significantly. It appears that tests of three-dimensional construction might be most sensitive to visuospatial construction deficits. Visuospatial construction involves the mediation of both frontal and parietal lobes. The function does not appear to be lateralized. The networks arising from the parieto-occipital areas and projecting to the frontal cortices (e.g., occipito-frontal fasciculus may be the basis of the mediation of both lobes in visuospatial construction. The present findings need replication from studies with larger sample sizes.
Bruner, Emiliano; Pereira-Pedro, Ana Sofia; Bastir, Markus
Modern humans have evolved bulging parietal areas and large, projecting temporal lobes. Both changes, largely due to a longitudinal expansion of these cranial and cerebral elements, were hypothesized to be the result of brain evolution and cognitive variations. Nonetheless, the independence of these two morphological characters has not been evaluated. Because of structural and functional integration among cranial elements, changes in the position of the temporal poles can be a secondary consequence of parietal bulging and reorientation of the head axis. In this study, we use geometric morphometrics to test the correlation between parietal shape and the morphology of the endocranial base in a sample of adult modern humans. Our results suggest that parietal proportions show no correlation with the relative position of the temporal poles within the spatial organization of the endocranial base. The vault and endocranial base are likely to be involved in distinct morphogenetic processes, with scarce or no integration between these two districts. Therefore, the current evidence rejects the hypothesis of reciprocal morphological influences between parietal and temporal morphology, suggesting that evolutionary spatial changes in these two areas may have been independent. However, parietal bulging exerts a visible effect on the rotation of the cranial base, influencing head position and orientation. This change can have had a major relevance in the reorganization of the head functional axis. © 2017 Wiley Periodicals, Inc.
Francine Judith Freitas Fernandes
Full Text Available A encefalopatia posterior reversível é uma síndrome aguda / subaguda geralmente causada pela encefalopatia hipertensiva, eclâmpsia, neurotoxicidade a ciclosporina-A, encefalopatia urêmica e púrpura trombocitopênica trombótica.. A maioria dos pacientes apresenta elevação acentuada dos níveis tensionais outros, níveis moderados ou normais. Os sintomas são progressivos e compreendem cefaléia, diminuição do nível de consciência, crises epilépticas e distúrbios visuais. A sintomatologia regride completamente se corrigidas em tempo as causas determinantes, caso contrário, podem instalar-se danos irreversíveis como a cegueira cortical e morte. A tomografia computadorizada (TC e, sobretudo, a ressonância magnética (RM contribuem para o diagnóstico. Tais métodos evidenciam edema da substância branca e cinzenta, principalmente das regiões parieto-occipitais. Os achados podem apresentar dificuldade no diagnóstico, hoje superado em parte, com a técnica de difusão pela RM, capaz de diferenciar edema citotóxico de vasogênico. Apresentamos um caso de encefalopatia posterior reversível decorrente de encefalopatia hipertensiva estudada com TC e RM.The posterior reversible leukoencephalopathy syndrome (PRES is a recently proposed cliniconeuroradiologic entity.The most common causes of PRES are hypertensive encephalopathy, eclampsia, cyclosporin A neurotoxicity and the uremic encephalopathies.Most patients are markedly hypertensive at presentation, although some have only middly elevated or even normal blood pressure. Symptoms may include headache, nausea , vomiting, altered mental status, seizures,stupor, and visual disturbances. On CT and MR studies, edema has been reported in a relatively symmetrical pattern, typically in the subcortical white matter and occasionally in the cortex of the occipital and parietal lobes. These often striking imaging findings usually are resolved on follow-up studies obtained after appropiate
Toth, Marton; Faludi, Bela; Kondakor, Istvan
Effects of initiation of continuous positive airway pressure (CPAP) therapy on EEG background activity were investigated in patients with obstructive sleep apnea syndrome (OSAS, N = 25) to test possible reversibility of alterations of brain electrical activity caused by chronic hypoxia. Normal control group (N = 14) was also examined. Two EEG examinations were done in each groups: at night and in the next morning. Global and regional (left vs. right, anterior vs. posterior) measures of spatial complexity (Omega complexity) were used to characterize the degree of spatial synchrony of EEG. Low resolution electromagnetic tomography (LORETA) was used to localize generators of EEG activity in separate frequency bands. Before CPAP-treatment, a significantly lower Omega complexity was found globally and over the right hemisphere. Due to CPAP-treatment, these significant differences vanished. Significantly decreased Omega complexity was found in the anterior region after treatment. LORETA showed a decreased activity in all of the beta bands after therapy in the right hippocampus, premotor and temporo-parietal cortex, and bilaterally in the precuneus, paracentral and posterior cingulate cortex. No significant changes were seen in control group. Comparing controls and patients before sleep, an increased alpha2 band activity was seen bilaterally in the precuneus, paracentral and posterior cingulate cortex, while in the morning an increased beta3 band activity in the left precentral and bilateral premotor cortex and a decreased delta band activity in the right temporo-parietal cortex and insula were observed. These findings indicate that effect of sleep on EEG background activity is different in OSAS patients and normal controls. In OSAS patients, significant changes lead to a more normal EEG after a night under CPAP-treatment. Compensatory alterations of brain electrical activity in regions associated with influencing sympathetic outflow, visuospatial abilities, long
Full Text Available Transcranial electrical stimulation (tES is being investigated as an experimental and clinical interventional technique in human participants. While promising, important limitations have been identified, including weak effect sizes and high inter- and intra-individual variability of outcomes. Here, we compared two “inhibitory” tES-techniques with supposedly different mechanisms of action as to their effects on performance in a visuospatial attention task, and report on a direct replication attempt. In two experiments, 2 × 20 healthy participants underwent tES in three separate sessions testing different protocols (10 min stimulation each with a montage targeting right parietal cortex (right parietal–left frontal, electrode-sizes: 3cm × 3cm–7 cm × 5 cm, while performing a perceptual line bisection (landmark task. The tES-protocols were compared as to their ability to modulate pseudoneglect (thought to be under right hemispheric control. In experiment 1, sham-tES was compared to transcranial alternating current stimulation at alpha frequency (10 Hz; α-tACS (expected to entrain “inhibitory” alpha oscillations and to cathodal transcranial direct current stimulation (c-tDCS (shown to suppress neuronal spiking activity. In experiment 2, we attempted to replicate the findings of experiment 1, and establish frequency-specificity by adding a 45 Hz-tACS condition to α-tACS and sham. In experiment 1, right parietal α-tACS led to the expected changes in spatial attention bias, namely a rightward shift in subjective midpoint estimation (relative to sham. However, this was not confirmed in experiment 2 and in the complete sample. Right parietal c-tDCS and 45 Hz-tACS had no effect. These results highlight the importance of replication studies, adequate statistical power and optimizing tES-interventions for establishing the robustness and reliability of electrical stimulation effects, and best practice.
Monge, Zachary A.; Greenwood, Pamela M.; Parasuraman, Raja; Strenziok, Maren
Objective Although reasoning and attention are two cognitive processes necessary for ensuring the efficiency of many everyday activities in older adults, the role of white matter integrity in these processes has been little studied. This is an important question due to the role of white matter integrity as a neural substrate of cognitive aging. Here, we sought to examine the white matter tracts subserving reasoning and visuospatial attention in healthy older adults. Method Sixty-one adults aged 60 and older completed a battery of cognitive tests to assess reasoning and visuospatial attention. In addition, diffusion tensor images were collected to assess Fractional Anisotropy (FA) – a measure of white matter integrity. A principle component analysis of the test scores yielded two components: reasoning and visuospatial attention. Whole-brain correlations between FA and the cognitive components were submitted to probabilistic tractography analyses for visualization of cortical targets of tracts. Results For reasoning, bilateral thalamo-anterior prefrontal, anterior corpus callosum, and corpus callosum body tracts interconnecting the superior frontal cortices and right cingulum bundle were found. For visuospatial attention, a right inferior fronto-parietal tract, and bilateral parietal and temporal connections were found. Conclusions We conclude that in older adults, prefrontal cortex white matter tracts and interhemispheric communication are important in higher order cognitive functioning. On the other hand, right-sided fronto-parietal tracts appear to be critical for supporting control of cognitive processes, such as redirecting attention. Researchers may use our results to develop neuroscience-based interventions for older adults targeting brain mechanisms involved in cognitive plasticity. PMID:26986750
Kobayashi, N.; Saito, Y.; Miyashita, T.; Tajika, Y.
Nine patients underwent metrizamide cisternography of the posterior fossa. Excellent opacification of the fourth ventricle resulted when the patient's head was suitably positioned and the contrast material was introduced via a C1-2 puncture. With this technique, a benign aqueductal stenosis can be readily identified and the posterior fossa and fourth ventricle can be studied easily.
tion in 95% of cases. The majority showed ... selective posterior rhizotomy technique whereby the cauda equina ... assessed pre- and postoperatively by means of clinical examination ... were attending cerebral palsy schools and receiving spe- cialised ... root sections on cats demonstrated clearly that posterior root section ...
Liberman, Daniel; Pagliara, Travis J; Pisansky, Andrew; Elliott, Sean P
Posterior urethral injury is a clinically significant complication of pelvic fractures. The management is complicated by the associated organ injuries, distortion of the pelvic anatomy and the ensuing fibrosis that occurs with urethral injury. We report a review of the outcomes after posterior urethroplasty in the context of pelvic fracture urethral injury.
Lobier, Muriel; Palva, J Matias; Palva, Satu
Visuospatial attention prioritizes processing of attended visual stimuli. It is characterized by lateralized alpha-band (8-14 Hz) amplitude suppression in visual cortex and increased neuronal activity in a network of frontal and parietal areas. It has remained unknown what mechanisms coordinate neuronal processing among frontoparietal network and visual cortices and implement the attention-related modulations of alpha-band amplitudes and behavior. We investigated whether large-scale network synchronization could be such a mechanism. We recorded human cortical activity with magnetoencephalography (MEG) during a visuospatial attention task. We then identified the frequencies and anatomical networks of inter-areal phase synchronization from source localized MEG data. We found that visuospatial attention is associated with robust and sustained long-range synchronization of cortical oscillations exclusively in the high-alpha (10-14 Hz) frequency band. This synchronization connected frontal, parietal and visual regions and was observed concurrently with amplitude suppression of low-alpha (6-9 Hz) band oscillations in visual cortex. Furthermore, stronger high-alpha phase synchronization was associated with decreased reaction times to attended stimuli and larger suppression of alpha-band amplitudes. These results thus show that high-alpha band phase synchronization is functionally significant and could coordinate the neuronal communication underlying the implementation of visuospatial attention. Copyright © 2017 Elsevier Inc. All rights reserved.
Full Text Available Despite its phylogenetic antiquity and clinical importance, the posterior cingulate cortex (CGp remains an enigmatic nexus of attention, memory, motivation, and decision making. Here we show that CGp neurons track decision salience—the degree to which an option differs from a standard—but not the subjective value of a decision. To do this, we recorded the spiking activity of CGp neurons in monkeys choosing between options varying in reward-related risk, delay to reward, and social outcomes, each of which varied in level of decision salience. Firing rates were higher when monkeys chose the risky option, consistent with their risk-seeking preferences, but were also higher when monkeys chose the delayed and social options, contradicting their preferences. Thus, across decision contexts, neuronal activity was uncorrelated with how much monkeys valued a given option, as inferred from choice. Instead, neuronal activity signaled the deviation of the chosen option from the standard, independently of how it differed. The observed decision salience signals suggest a role for CGp in the flexible allocation of neural resources to motivationally significant information, akin to the role of attention in selective processing of sensory inputs.
Full Text Available Compared to our understanding of the functional maturation of executive functions, little is known about the neurofunctional development of perceptive functions. Time perception develops during late adolescence, underpinning many functions including motor and verbal processing, as well as late maturing higher order cognitive skills such as forward planning and future-related decision-making. Nothing, however, is known about the neurofunctional changes associated with time perception from childhood to adulthood. Using functional magnetic resonance imaging we explored the effects of age on the brain activation and functional connectivity of 32 male participants from 10 to 53 years of age during a time discrimination task that required the discrimination of temporal intervals of seconds differing by several hundred milliseconds. Increasing development was associated with progressive activation increases within left lateralised dorsolateral and inferior fronto-parieto-striato-thalamic brain regions. Furthermore, despite comparable task performance, adults showed increased functional connectivity between inferior/dorsolateral interhemispheric fronto-frontal activation as well as between inferior fronto-parietal regions compared with adolescents. Activation in caudate, specifically, was associated with both increasing age and better temporal discrimination. Progressive decreases in activation with age were observed in ventromedial prefrontal cortex, limbic regions and cerebellum. The findings demonstrate age-dependent developmentally dissociated neural networks for time discrimination. With increasing age there is progressive recruitment of later maturing left hemispheric and lateralised fronto-parieto-striato-thalamic networks, known to mediate time discrimination in adults, while earlier developing brain regions such as ventromedial prefrontal cortex, limbic and paralimbic areas and cerebellum subserve fine-temporal processing functions in children
Full Text Available Working memory training has been widely used to investigate working memory processes. We have shown previously that visual working memory benefits only from intra-modal visual but not from across-modal auditory working memory training. In the present functional magnetic resonance imaging study we examined whether auditory working memory processes can also be trained specifically and which training-induced activation changes accompany theses effects. It was investigated whether working memory training with strongly distinct auditory materials transfers exclusively to an auditory (intra-modal working memory task or whether it generalizes to an (across-modal visual working memory task. We used an adaptive n-back training with tonal sequences and a passive control condition. The memory training led to a reliable training gain. Transfer effects were found for the (intra-modal auditory but not for the (across-modal visual 2-back task. Training-induced activation changes in the auditory 2-back task were found in two regions in the right inferior frontal gyrus. These effects confirm our previous findings in the visual modality and extends intra-modal effects to the auditory modality. These results might reflect increased neural efficiency in auditory working memory processes as in the right inferior frontal gyrus is frequently found in maintaining modality-specific auditory information. By this, these effects are analogical to the activation decreases in the right middle frontal gyrus for the visual modality in our previous study. Furthermore, task-unspecific (across-modal activation decreases in the visual and auditory 2-back task were found in the right inferior parietal lobule and the superior portion of the right middle frontal gyrus reflecting less demands on general attentional control processes. These data are in good agreement with across-modal activation decreases within the same brain regions on a visual 2-back task reported previously.
Wilcox, Teresa; Hawkins, Laura B; Hirshkowitz, Amy; Boas, David A
A great deal is known about the functional organization of cortical networks that mediate visual object processing in the adult. The current research is part of a growing effort to identify the functional maturation of these pathways in the developing brain. The current research used near-infrared spectroscopy to investigate functional activation of the infant cortex during the processing of featural information (shape) and spatiotemporal information (speed of motion) during the first year of life. Our investigation focused on two areas that were implicated in previous studies: anterior temporal cortex and posterior parietal cortex. Neuroimaging data were collected with 207 infants across three age groups: 3-6 months (Experiment 1), 7-8 months (Experiment 2), and 10-12 months (Experiments 3 and 4). The neuroimaging data revealed age-related changes in patterns of activation to shape and speed information, mostly involving posterior parietal areas, some of which were predicted and others that were not. We suggest that these changes reflect age-related differences in the perceptual and/or cognitive processes engaged during the task. Copyright © 2014 Elsevier Inc. All rights reserved.
Crescentini, Cristiano; Di Bucchianico, Marilena; Fabbro, Franco; Urgesi, Cosimo
Although religiousness and spirituality (RS) are considered two fundamental constituents of human life, neuroscientific investigation has long avoided the study of their neurocognitive basis. Nevertheless, recent investigations with brain imaging and brain damaged patients, and more recently with brain stimulation methods, have documented important associations between RS beliefs and experiences and frontoparietal neural activity. In this study, we further investigated how individuals' implicit RS self-representations can be modulated by changes in right inferior parietal lobe (IPL) excitability, a key region associated to RS. To this end, we combined continuous theta burst stimulation (cTBS), intermittent TBS (iTBS), and sham TBS with RS-related, Implicit Association Test (IAT) and with a control self-esteem (SE) IAT in a group of fourteen healthy adult individuals. A specific decrease of implicit RS, as measured with the IAT effect, was induced by increasing IPL excitability with iTBS; conversely cTBS, which is supposedly inhibitory, left participants' implicit RS unchanged. The performance in the control SE-IAT was left unchanged by any TBS stimulation. These data showed the causative role of right IPL functional state in mediating plastic changes of implicit RS. Implications of these results are also discussed in the light of the variability of behavioral effects associated with TBS. Copyright © 2015 Elsevier Ltd. All rights reserved.
Full Text Available Executive-attention theory proposes a close relationship between working memory capacity (WMC and cognitive control abilities. However, conflicting results are documented in the literature, with some studies reporting that individual variations in WMC predict differences in cognitive control and trial-to-trial control adjustments (operationalized as the size of the congruency effect and congruency sequence effects, respectively, while others report no WMC-related differences. We hypothesized that brain network dynamics might be a more sensitive measure of WMC-related differences in cognitive control abilities. Thus, in the present study, we measured human EEG during the Simon task to characterize WMC-related differences in the neural dynamics of conflict processing and adaptation to conflict. Although high- and low-WMC individuals did not differ behaviorally, there were substantial WMC-related differences in theta (4-8 Hz and delta (1-3 Hz connectivity in fronto-parietal networks. Group differences in local theta and delta power were relatively less pronounced. These results suggest that the relationship between WMC and cognitive control abilities is more strongly reflected in large-scale oscillatory network dynamics than in spatially localized activity or in behavioral task performance.
Eng, Diana G.; Sunseri, Maria W.; Kaverina, Natalya; Roeder, Sebastian S.; Pippin, Jeffrey W.; Shankland, Stuart J.
Since adult podocytes cannot adequately proliferate following depletion in disease states there has been interest in the potential role of progenitors in podocyte repair and regeneration. To determine if parietal epithelial cells (PECs) can serve as adult podocyte progenitors following disease-induced podocyte depletion, PECs were permanently labeled in adult PECrtTA/LC1/R26 reporter mice. In normal mice, labeled PECs were confined to Bowman's capsule, while in disease (cytotoxic sheep anti-podocyte antibody), labeled PECs were found in the glomerular tuft in progressively higher numbers by days 7, 14 and 28. Early in disease, the majority of PECs in the tuft co-expressed CD44. By day 28, when podocyte numbers were significantly higher and disease severity was significantly lower, the majority of labeled PECs co-expressed podocyte proteins but not CD44. Neither labeled PECs on the tuft, nor podocytes stained for the proliferation marker BrdU. The de novo expression of phospho-ERK colocalized to CD44 expressing PECs, but not to PECs expressing podocyte markers. Thus, in a mouse model of focal segmental glomerulosclerosis typified by abrupt podocyte depletion followed by regeneration, PECs undergo two phenotypic changes once they migrate to the glomerular tuft. Initially these cells are predominantly activated CD44 expressing cells coinciding with glomerulosclerosis, and later they predominantly exhibit a podocyte phenotype which is likely reparative. PMID:25993321
Hamatani, Hiroko; Sakairi, Toru; Takahashi, Satoshi; Watanabe, Mitsuharu; Maeshima, Akito; Ohse, Takamoto; Pippin, Jeffery W.; Shankland, Stuart J.; Nojima, Yoshihisa
Sestrin 2, initially identified as a p53 target protein, accumulates in cells exposed to stress and inhibits mammalian target of rapamycin (mTOR) signaling. In normal rat kidneys, sestrin 2 was selectively expressed in parietal epithelial cells (PECs), identified by the marker protein gene product 9.5. In adriamycin nephropathy, sestrin 2 expression decreased in PECs on day 14, together with increased expression of phosphorylated S6 ribosomal protein (P-S6RP), a downstream target of mTOR. Sestrin 2 expression was markedly decreased on day 42, coinciding with glomerulosclerosis and severe periglomerular fibrosis. In puromycin aminonucleoside nephropathy, decreased sestrin 2 expression, increased P-S6RP expression, and periglomerular fibrosis were observed on day 9, when massive proteinuria developed. These changes were transient and nearly normalized by day 28. In crescentic glomerulonephritis, sestrin 2 expression was not detected in cellular crescents, whereas P-S6RP increased. In conditionally immortalized cultured PECs, the forced downregulation of sestrin 2 by short hairpin RNA resulted in increased expression of P-S6RP and increased apoptosis. These data suggest that sestrin 2 is involved in PEC homeostasis by regulating the activity of mTOR. In addition, sestrin 2 could be a novel marker of PECs, and decreased expression of sestrin 2 might be a marker of PEC injury. PMID:25056347
Eng, Diana G; Sunseri, Maria W; Kaverina, Natalya V; Roeder, Sebastian S; Pippin, Jeffrey W; Shankland, Stuart J
As adult podocytes cannot adequately proliferate following depletion in disease states, there has been interest in the potential role of progenitors in podocyte repair and regeneration. To determine whether parietal epithelial cells (PECs) can serve as adult podocyte progenitors following disease-induced podocyte depletion, PECs were permanently labeled in adult PEC-rtTA/LC1/R26 reporter mice. In normal mice, labeled PECs were confined to Bowman's capsule, whereas in disease (cytotoxic sheep anti-podocyte antibody) labeled PECs were found in the glomerular tuft in progressively higher numbers by days 7, 14, and 28. Early in disease, the majority of PECs in the tuft coexpressed CD44. By day 28, when podocyte numbers were significantly higher and disease severity was significantly lower, the majority of labeled PECs coexpressed podocyte proteins but not CD44. Neither labeled PECs on the tuft nor podocytes stained for the proliferation marker BrdU. The de novo expression of phospho-ERK colocalized to CD44 expressing PECs, but not to PECs expressing podocyte markers. Thus, in a mouse model of focal segmental glomerulosclerosis typified by abrupt podocyte depletion followed by regeneration, PECs undergo two phenotypic changes once they migrate to the glomerular tuft. Initially these cells are predominantly activated CD44 expressing cells coinciding with glomerulosclerosis, and later they predominantly exhibit a podocyte phenotype, which is likely reparative.
Schneiders, Julia A; Opitz, Bertram; Tang, Huijun; Deng, Yuan; Xie, Chaoxiang; Li, Hong; Mecklinger, Axel
Working memory training has been widely used to investigate working memory processes. We have shown previously that visual working memory benefits only from intra-modal visual but not from across-modal auditory working memory training. In the present functional magnetic resonance imaging study we examined whether auditory working memory processes can also be trained specifically and which training-induced activation changes accompany theses effects. It was investigated whether working memory training with strongly distinct auditory materials transfers exclusively to an auditory (intra-modal) working memory task or whether it generalizes to a (across-modal) visual working memory task. We used adaptive n-back training with tonal sequences and a passive control condition. The memory training led to a reliable training gain. Transfer effects were found for the (intra-modal) auditory but not for the (across-modal) visual transfer task. Training-induced activation decreases in the auditory transfer task were found in two regions in the right inferior frontal gyrus. These effects confirm our previous findings in the visual modality and extents intra-modal effects in the prefrontal cortex to the auditory modality. As the right inferior frontal gyrus is frequently found in maintaining modality-specific auditory information, these results might reflect increased neural efficiency in auditory working memory processes. Furthermore, task-unspecific (amodal) activation decreases in the visual and auditory transfer task were found in the right inferior parietal lobule and the superior portion of the right middle frontal gyrus reflecting less demand on general attentional control processes. These data are in good agreement with amodal activation decreases within the same brain regions on a visual transfer task reported previously.
Full Text Available The goals of the present study were twofold. First, we wished to investigate the neural correlates of stimulus-driven processing of stimuli strongly suppressed from awareness and in the absence of top-down influences. We accomplished this using a novel approach in which participants performed an orthogonal task atop a flash suppression noise image to prevent top-down search. Second, we wished to investigate the extent to which amygdala responses differentiate between suppressed stimuli (fearful faces and houses based on their motivational relevance. Using continuous flash suppression in conjunction with fMRI, we presented fearful faces, houses, and a no stimulus control to one eye while participants performed an orthogonal task that appeared atop the flashing Mondrian image presented to the opposite eye. In 29 adolescents, we show activation in subcortical regions, including the superior colliculus, amygdala, thalamus, and hippocampus for suppressed objects (fearful faces and houses compared to a no stimulus control. Suppressed stimuli showed less activation compared to a no stimulus control in early visual cortex, indicating that object information was being suppressed from this region. Additionally, we find no activation in regions associated with conscious processing of these percepts (fusiform gyrus and/or parahippocampal cortex as assessed by mean activations and multi-voxel patterns. A psychophysiological interaction analysis that seeded the amygdala showed task-specific (fearful faces greater than houses modulation of right pulvinar and left inferior parietal cortex. Taken together, our results support a role for the amygdala in stimulus-driven attentional guidance towards objects of relevance and a potential mechanism for successful suppression of rivalrous stimuli.
Schneiders, Julia A.; Opitz, Bertram; Tang, Huijun; Deng, Yuan; Xie, Chaoxiang; Li, Hong; Mecklinger, Axel
Working memory training has been widely used to investigate working memory processes. We have shown previously that visual working memory benefits only from intra-modal visual but not from across-modal auditory working memory training. In the present functional magnetic resonance imaging study we examined whether auditory working memory processes can also be trained specifically and which training-induced activation changes accompany theses effects. It was investigated whether working memory training with strongly distinct auditory materials transfers exclusively to an auditory (intra-modal) working memory task or whether it generalizes to a (across-modal) visual working memory task. We used adaptive n-back training with tonal sequences and a passive control condition. The memory training led to a reliable training gain. Transfer effects were found for the (intra-modal) auditory but not for the (across-modal) visual transfer task. Training-induced activation decreases in the auditory transfer task were found in two regions in the right inferior frontal gyrus. These effects confirm our previous findings in the visual modality and extents intra-modal effects in the prefrontal cortex to the auditory modality. As the right inferior frontal gyrus is frequently found in maintaining modality-specific auditory information, these results might reflect increased neural efficiency in auditory working memory processes. Furthermore, task-unspecific (amodal) activation decreases in the visual and auditory transfer task were found in the right inferior parietal lobule and the superior portion of the right middle frontal gyrus reflecting less demand on general attentional control processes. These data are in good agreement with amodal activation decreases within the same brain regions on a visual transfer task reported previously. PMID:22701418
Thilander, Birgit; Bjerklin, Krister
The aim of this work was to update the bibliography regarding the concept of 'temporomandibular disorder (TMD)' and 'posterior crossbite' and try to find out if there is any association between some special signs/symptoms of TMD and type of posterior crossbite. A literature search from 1970 to 2009, due to specified criterion, resulted in 14 publications that were found to be relevant for the present systematic review. An association between TMD and posterior crossbite (Yes-group) was reported as often as absence of such a relationship (No-group). The samples in the two groups showed similarities as well as differences with respect to number, gender, and age. Most articles reported only on 'presence' or 'absence' of crossbite and only few on type of crossbite opposite to a thorough account of clinical signs and symptoms of TMD. This review seems, however, to state that a functional posterior crossbite (mandibular guidance with midline deviation) is associated with headache, temporomandibular joint and muscular pain, and clicking. As evident from the discussion, such type needs orthodontic treatment to rehabilitate the asymmetric muscular activity between the crossbite and non-crossbite sides and the changed condyle/temporal relationship caused by mandibular deviation. Whether this treatment also will avoid future TMD problems can be answered only after clinical follow-up studies have been performed.
Mair, S D; Zarzour, R H; Speer, K P
Nine athletes (seven football offensive linemen, one defensive lineman, and one lacrosse player) were found at arthroscopy to have posterior labral detachment from the glenoid. In our series, this lesion is specific to contact athletes who engage their opponents with arms in front of the body. All patients had pain with bench pressing and while participating in their sport, diminishing their ability to play effectively. Conservative measures were ineffective in relieving their symptoms. Examination under anesthesia revealed symmetric glenohumeral translation bilaterally, without evidence of posterior instability. Treatment consisted of glenoid rim abradement and posterior labral repair with a bioabsorbable tack. All patients returned to complete at least one full season of contact sports and weightlifting without pain (minimum follow-up, > or = 2 years). Although many injuries leading to subluxation of the glenohumeral joint occur when an unanticipated force is applied, contact athletes ready their shoulder muscles in anticipation of impact with opponents. This leads to a compressive force at the glenohumeral joint. We hypothesize that, in combination with a posteriorly directed force at impact, the resultant vector is a shearing force to the posterior labrum and articular surface. Repeated exposure leads to posterior labral detachment without capsular injury. Posterior labral reattachment provides consistently good results, allowing the athlete to return to competition.
Ramaswamy, Vijay; Taylor, Michael D
Posterior fossa ependymoma comprises two distinct molecular entities, ependymoma_posterior fossa A (EPN_PFA) and ependymoma_posterior fossa B (EPN_PFB), with differentiable gene expression profiles. As yet, the response of the two entities to treatment is unclear. To determine the relationship between the two molecular subgroups of posterior fossa ependymoma and treatment, we studied a cohort of 820 patients with molecularly profiled, clinically annotated posterior fossa ependymomas. We found that the strongest predictor of poor outcome in patients with posterior fossa ependymoma across the entire age spectrum was molecular subgroup EPN_PFA, which was recently reported in the paper entitled "Therapeutic impact of cytoreductive surgery and irradiation of posterior fossa ependymoma in the molecular era: a retrospective multicohort analysis" in the Journal of Clinical Oncology. Patients with incompletely resected EPN_PFA tumors had a very poor outcome despite receiving adjuvant radiation therapy, whereas a substantial proportion of patients with EPN_PFB tumors can be cured with surgery alone.
Weidauer, S.; Gaa, J.; Lanfermann, H.; Zanella, F.E.; Sitzer, M.; Hefner, R.
Posterior encephalopathy is characterised by headache, impairment of consciousness, seizures and progressive visual loss. MRI shows bilateral, predominantly posterior, cortical and subcortical lesions with a distribution. Our aim was to analyse the MRI lesion pattern and angiographic findings because the pathophysiology of posterior encephalopathy is incompletely understood. We report three patients with clinical and imaging findings consistent with posterior encephalopathy who underwent serial MRI including diffusion-weighted imaging (DWI) and construction of apparent diffusion coefficient (ADC) maps, and four-vessel digital subtraction angiography (DSA). DWI revealed symmetrical subcortical and cortical parieto-occipital high signal. High and also low ADCs indicated probable vasogenic and cytotoxic oedema. On follow-up there was focal cortical laminar necrosis, while the white-matter lesions resolved almost completely, except in the arterial border zones. DSA revealed diffuse arterial narrowing, slightly more marked in the posterior circulation. These findings suggest that posterior encephalopathy may in some cases be due to diffuse, severe vasospasm affecting especially in the parieto-occipital grey matter, with its higher vulnerability to ischemia. Cerebral vasospasm due to digitoxin intoxication, resulting in posterior encephalopathy, has not yet been described previously. (orig.)
Herwig, Uwe; Kaffenberger, Tina; Schell, Caroline; Jäncke, Lutz; Brühl, Annette B
Self-referential cognitions are important for self-monitoring and self-regulation. Previous studies have addressed the neural correlates of self-referential processes in response to or related to external stimuli. We here investigated brain activity associated with a short, exclusively mental process of self-reflection in the absence of external stimuli or behavioural requirements. Healthy subjects reflected either on themselves, a personally known or an unknown person during functional magnetic resonance imaging (fMRI). The reflection period was initialized by a cue and followed by photographs of the respective persons (perception of pictures of oneself or the other person). Self-reflection, compared with reflecting on the other persons and to a major part also compared with perceiving photographs of one-self, was associated with more prominent dorsomedial and lateral prefrontal, insular, anterior and posterior cingulate activations. Whereas some of these areas showed activity in the "other"-conditions as well, self-selective characteristics were revealed in right dorsolateral prefrontal and posterior cingulate cortex for self-reflection; in anterior cingulate cortex for self-perception and in the left inferior parietal lobe for self-reflection and -perception. Altogether, cingulate, medial and lateral prefrontal, insular and inferior parietal regions show relevance for self-related cognitions, with in part self-specificity in terms of comparison with the known-, unknown- and perception-conditions. Notably, the results are obtained here without behavioural response supporting the reliability of this methodological approach of applying a solely mental intervention. We suggest considering the reported structures when investigating psychopathologically affected self-related processing.
Full Text Available Reading is a fundamental human capacity and yet it can easily be derailed by the simple act of mind-wandering. A large-scale brain network, referred to as the default mode network (DMN, has been shown to be involved in both mind-wandering and reading, raising the question as to how the same neural system could be implicated in processes with both costs and benefits to narrative comprehension. Resting-state functional magnetic resonance imaging (rs-fMRI was used to explore whether the intrinsic functional connectivity of the two key midline hubs of the DMN — the posterior cingulate (PCC and medial prefrontal cortex (aMPFC — was predictive of individual differences in reading effectiveness (better comprehension, superior and task focus recorded outside of the scanner. Worse comprehension was associated with greater functional connectivity between the PCC and a region of the ventral striatum. By contrast reports of increasing task focus were associated with functional connectivity from the aMPFC to clusters in the PCC, the left parietal and temporal cortex, and the cerebellum. Our results suggest that the DMN has both costs (such as poor comprehension and benefits to reading (such as an on-task focus because its midline core can couple its activity with other regions to form distinct functional communities that allow seemingly opposing mental states to occur. This flexible coupling allows the DMN to participate in cognitive states that complement the act of reading as well as others that do not.
Therese eVan Amelsvoort
Full Text Available Executive function deficits such as working memory, decision-making, and attention problems are a common feature of several psychiatric disorders for which no satisfactory treatment exists. Here, we transdiagnostically investigate the effects of pharmacological interventions (other than methylphenidate on the fronto-cingulo-parietal cognitive control network, in order to identify functional brain markers for future pro-cognitive pharmacological interventions. 29 manuscripts investigated the effect of pharmacological treatment on executive function-related brain correlates in psychotic disorders (n=11, depression (n=4, bipolar disorder (n=4, ADHD (n=4, OCD (n=2, smoking dependence (n=2, alcohol dependence (n=1 and pathological gambling (n=1. In terms of impact on the fronto-cingulo-parietal networks, the preliminary evidence for catechol-o-methyl-transferase inhibitors, nicotinic receptor agonists and atomoxetine suggested was relatively consistent, the data for atypical antipsychotics and anticonvulsants moderate, and interpretation of the data for antidepressants was hampered by the employed study designs. Increased activity in task-relevant areas and decreased activity in task-irrelevant areas were the most common transdiagnostic effects of pharmacological treatment. These markers showed good positive and moderate negative predictive value. It is concluded that fronto-cingulo-parietal activity changes can serve as a marker for future pro-cognitive interventions. Future recommendations include the use of randomized double-blind designs and selective cholinergic and glutamatergic compounds.
Full Text Available Functional magnetic resonance imaging (fMRI in the resting state has shown altered brain connectivity networks in obese individuals. However, the impact of a Mediterranean diet on cerebral connectivity in obese patients when losing weight has not been previously explored. The aim of this study was to examine the connectivity between brain structures before and six months after following a hypocaloric Mediterranean diet and physical activity program in a group of sixteen obese women aged 46.31 ± 4.07 years. Before and after the intervention program, the body mass index (BMI (kg/m2 was 38.15 ± 4.7 vs. 34.18 ± 4.5 (p < 0.02, and body weight (kg was 98.5 ± 13.1 vs. 88.28 ± 12.2 (p < 0.03. All subjects underwent a pre- and post-intervention fMRI under fasting conditions. Functional connectivity was assessed using seed-based correlations. After the intervention, we found decreased connectivity between the left inferior parietal cortex and the right temporal cortex (p < 0.001, left posterior cingulate (p < 0.001, and right posterior cingulate (p < 0.03; decreased connectivity between the left superior frontal gyrus and the right temporal cortex (p < 0.01; decreased connectivity between the prefrontal cortex and the somatosensory cortex (p < 0.025; and decreased connectivity between the left and right posterior cingulate (p < 0.04. Results were considered significant at a voxel-wise threshold of p ≤ 0.05, and a cluster-level family-wise error correction for multiple comparisons of p ≤ 0.05. In conclusion, functional connectivity between brain structures involved in the pathophysiology of obesity (the inferior parietal lobe, posterior cingulate, temporo-insular cortex, prefrontal cortex may be modified by a weight loss program including a Mediterranean diet and physical exercise.
Tapia, Evelina; Mazzi, Chiara; Savazzi, Silvia; Beck, Diane M.
Transcranial magnetic stimulation (TMS) applied over the occipital lobe approximately 100 ms after the onset of a stimulus decreases its visibility if it appears in the location of the phosphene. Because phosphenes can also be elicited by stimulation of the parietal regions, we asked if the same procedure that is used to reduce visibility of stimuli with occipital TMS will lead to decreased stimulus visibility when TMS is applied to parietal regions. TMS was randomly applied at 0 to 130 ms after the onset of the stimulus (SOA) in steps of 10 ms in occipital and parietal regions. Participants responded to the orientation of the line stimulus and rated its visibility. We replicate previous reports of phosphenes from both occipital and parietal TMS. As previously reported, we also observed visual suppression around the classical 100 ms window both in the objective line orientation and subjective visibility responses with occipital TMS. Parietal stimulation, on the other hand, did not consistently reduce stimulus visibility in any time window. PMID:24584900
Chen, Quanjing; Garcea, Frank E; Jacobs, Robert A; Mahon, Bradford Z
Prior neuroimaging and neuropsychological research indicates that the left inferior parietal lobule in the human brain is a critical substrate for representing object manipulation knowledge. In the present functional MRI study we used multivoxel pattern analyses to test whether action similarity among objects can be decoded in the inferior parietal lobule independent of the task applied to objects (identification or pantomime) and stimulus format in which stimuli are presented (pictures or printed words). Participants pantomimed the use of objects, cued by printed words, or identified pictures of objects. Classifiers were trained and tested across task (e.g., training data: pantomime; testing data: identification), stimulus format (e.g., training data: word format; testing format: picture) and specific objects (e.g., training data: scissors vs. corkscrew; testing data: pliers vs. screwdriver). The only brain region in which action relations among objects could be decoded across task, stimulus format and objects was the inferior parietal lobule. By contrast, medial aspects of the ventral surface of the left temporal lobe represented object function, albeit not at the same level of abstractness as actions in the inferior parietal lobule. These results suggest compulsory access to abstract action information in the inferior parietal lobe even when simply identifying objects.
Alonso, Mariana; Bekinschtein, Pedro; Cammarota, Martín; Vianna, Monica R M; Izquierdo, Iván; Medina, Jorge H
Information storage in the brain is a temporally graded process involving different memory phases as well as different structures in the mammalian brain. Cortical plasticity seems to be essential to store stable long-term memories, although little information is available at the moment regarding molecular and cellular events supporting memory consolidation in the neocortex. Brain-derived neurotrophic factor (BDNF) modulates both short-term synaptic function and activity-dependent synaptic plasticity in hippocampal and cortical neurons. We have recently demonstrated that endogenous BDNF in the hippocampus is involved in memory formation. Here we examined the role of BDNF in the parietal cortex (PCx) in short-term (STM) and long-term memory (LTM) formation of a one-trial fear-motivated learning task in rats. Bilateral infusions of function-blocking anti-BDNF antibody into the PCx impaired both STM and LTM retention scores and decreased the phosphorylation state of cAMP response element-binding protein (CREB). In contrast, intracortical administration of recombinant human BDNF facilitated LTM and increased CREB activation. Moreover, inhibitory avoidance training is associated with a rapid and transient increase in phospho-CREB/total CREB ratio in the PCx. Thus, our results indicate that endogenous BDNF is required for both STM and LTM formation of inhibitory avoidance learning, possibly involving CREB activation-dependent mechanisms. The present data support the idea that early sensory areas constitute important components of the networks subserving memory formation and that information processing in neocortex plays an important role in memory formation.
Berger, Joseph R; Neltner, Janna; Smith, Charles; Cambi, Franca