The Experts below are selected from a list of 3363 Experts worldwide ranked by ideXlab platform

Burkhard Pleger - One of the best experts on this subject based on the ideXlab platform.

  • fat perception in the human frontal operculum insular and Somatosensory Cortex
    Scientific Reports, 2018
    Co-Authors: Thomas Wistehube, Peggy G Braun, Claudia Wiacek, Michael Rullmann, Burkhard Pleger
    Abstract:

    Here, we combined magnetic resonance imaging with lesion-symptom mapping in patients with chronic brain lesions to investigate brain representations of sugar and fat perception. Patients and healthy controls rated chocolate milkshakes that only differed in sugar or fat content. As compared to controls, patients showed an impaired fat, but not sugar perception. Impairments in fat perception overlapped with the anterior insula and frontal operculum, together assumed to underpin gustatory processing. We also identified the mid-dorsal insula as well as the primary and Secondary Somatosensory Cortex - regions previously assumed to integrate oral-sensory inputs. These findings suggest that fat perception involves a specific set of brain regions that were previously reported to underpin gustatory processing and oral-sensory integration processes.

  • Differential cerebral response to Somatosensory stimulation of an acupuncture point vs. two non-acupuncture points measured with EEG and fMRI.
    Frontiers in Human Neuroscience, 2015
    Co-Authors: Till Nierhaus, Burkhard Pleger, Arno Villringer, Daniel Pach, Wenjing Huang, Xiangyu Long, Vitaly Napadow, Stephanie Roll, Fanrong Liang, Claudia M. Witt
    Abstract:

    Acupuncture can be regarded as a complex Somatosensory stimulation. Here, we evaluate whether the point locations chosen for a Somatosensory stimulation with acupuncture needles differently change the brain activity in healthy volunteers. We used EEG, event-related fMRI, and resting-state functional connectivity fMRI to assess neural responses to standardized needle stimulation of the acupuncture point ST36 (lower leg) and two control point locations (CP1 same dermatome, CP2 different dermatome). Cerebral responses were expected to differ for stimulation in two different dermatomes (CP2 different from ST36 & CP1), or stimulation at the acupuncture point versus the control points. For EEG, mu rhythm power increased for ST36 compared to CP1 or CP2, but not when comparing the two control points. The fMRI analysis found more pronounced insula and S2 (Secondary Somatosensory Cortex) activation, as well as precuneus deactivation during ST36 stimulation. The S2 seed-based functional connectivity analysis revealed increased connectivity to right precuneus for both comparisons, ST36 vs. CP1 and ST36 vs. CP2, however in different regions. Our results suggest that stimulation at acupuncture points may modulate Somatosensory and saliency processing regions more readily than stimulation at non-acupuncture point locations. Also, our findings suggest potential modulation of pain perception due to acupuncture stimulation.

  • sensorimotor returning in complex regional pain syndrome parallels pain reduction
    Annals of Neurology, 2005
    Co-Authors: Burkhard Pleger, Peter Schwenkreis, Patrick Ragert, Martin Tegenthoff, Hubert R. Dinse, Annfreya Forster, Volkmar Nicolas, Christoph Maier
    Abstract:

    Patients with complex regional pain syndrome (CRPS) and intractable pain showed a shrinkage of cortical maps on primary (SI) and Secondary Somatosensory Cortex (SII) contralateral to the affected limb. This was paralleled by an impairment of the two-point discrimination thresholds. Behavioral treatment over 1 to 6 months consisting of graded sensorimotor retuning led to a persistent decrease in pain intensity, which was accompanied by a restoration of the impaired tactile discrimination and regaining of cortical map size in contralateral SI and SII. This suggests that the reversal of tactile impairment and cortical reorganization in CRPS is associated with a decrease in pain.

  • functional imaging of perceptual learning in human primary and Secondary Somatosensory Cortex
    Neuron, 2003
    Co-Authors: Burkhard Pleger, Peter Schwenkreis, Patrick Ragert, Hubert R. Dinse, Volkmar Nicolas, Ann Freya Foerster, Jean Pierre Malin, Martin Tegenthoff
    Abstract:

    Cellular mechanisms underlying synaptic plasticity are in line with the Hebbian concept. In contrast, data linking Hebbian learning to altered perception are rare. Combining functional magnetic resonance imaging with psychophysical tests, we studied cortical reorganization in primary and Secondary Somatosensory Cortex (SI and SII) and the resulting changes of tactile perception before and after tactile coactivation, a simple type of Hebbian learning. Coactivation on the right index finger (IF) for 3 hr lowered its spatial discrimination threshold. In parallel, blood-oxygen level-dependent (BOLD) signals from the right IF representation in SI and SII enlarged. The individual threshold reduction was linearly correlated with the enlargement in SI, implying a close relation between altered discrimination and cortical reorganization. Controls consisting of a single-site stimulation did not affect thresholds and cortical maps. Accordingly, changes within distributed cortical networks based on Hebbian mechanisms alter the individual percept.

Patrick Haggard - One of the best experts on this subject based on the ideXlab platform.

  • transcranial magnetic stimulation over human Secondary Somatosensory Cortex disrupts perception of pain intensity
    Cortex, 2013
    Co-Authors: Patricia L Lockwood, Gian Domenico Iannetti, Patrick Haggard
    Abstract:

    Pain is a complex sensory experience resulting from the activity of a network of brain regions. However, the functional contribution of individual regions in this network remains poorly understood. We delivered single-pulse transcranial magnetic stimulation (TMS) to the contralateral primary Somatosensory Cortex (S1), Secondary Somatosensory Cortex (S2) and vertex (control site) 120 msec after selective stimulation of nociceptive afferents using neodymium:yttrium–aluminium–perovskite (Nd:YAP) laser pulses causing painful sensations. Participants were required to judge either the intensity (medium/high) or the spatial location (proximal/distal) of the stimulus in a two-alternative forced choice paradigm. When TMS pulses were delivered over S2, participants' ability to judge pain intensity was disrupted, as compared to S1 and vertex (control) stimulation. Signal-detection analysis demonstrated a loss of sensitivity to stimulation intensity, rather than a shift in perceived pain level or response bias. We did not find any effect of TMS on the ability to localise nociceptive stimuli on the skin. The novel finding that TMS over S2 can disrupt perception of pain intensity suggests a causal role for S2 in encoding of pain intensity.

  • sensory neuroscience from skin to object in the Somatosensory Cortex
    Current Biology, 2006
    Co-Authors: Patrick Haggard
    Abstract:

    Humans can perceive the shape of objects by touch alone, by extracting geometric features such as edges. Recently recorded responses of single neurons in the Secondary Somatosensory Cortex of monkeys suggest how the brain integrates tactile shape information across different regions of skin and builds up a representation of tactile objects.

Peter Brugger - One of the best experts on this subject based on the ideXlab platform.

  • the desire for healthy limb amputation structural brain correlates and clinical features of xenomelia
    Brain, 2013
    Co-Authors: Leonie M Hilti, Jurgen Hanggi, Deborah A Vitacco, Bernd Kraemer, Antonella Palla, Roger Luechinger, Lutz Jancke, Peter Brugger
    Abstract:

    Xenomelia is the oppressive feeling that one or more limbs of one’s body do not belong to one’s self. We present the results of a thorough examination of the characteristics of the disorder in 15 males with a strong desire for amputation of one or both legs. The feeling of estrangement had been present since early childhood and was limited to a precisely demarcated part of the leg in all individuals. Neurological status examination and neuropsychological testing were normal in all participants, and psychiatric evaluation ruled out the presence of a psychotic disorder. In 13 individuals and in 13 pair-matched control participants, magnetic resonance imaging was performed, and surface-based morphometry revealed significant group differences in cortical architecture. In the right hemisphere, participants with xenomelia showed reduced cortical thickness in the superior parietal lobule and reduced cortical surface area in the primary and Secondary Somatosensory cortices, in the inferior parietal lobule, as well as in the anterior insular Cortex. A cluster of increased thickness was located in the central sulcus. In the left hemisphere, affected individuals evinced a larger cortical surface area in the inferior parietal lobule and Secondary Somatosensory Cortex. Although of modest size, these structural correlates of xenomelia appear meaningful when discussed against the background of some key clinical features of the disorder. Thus, the predominantly right-sided cortical abnormalities are in line with a strong bias for left-sided limbs as the target of the amputation desire, evident both in our sample and in previously described populations with xenomelia. We also propose that the higher incidence of lower compared with upper limbs (∼80% according to previous investigations) may explain the erotic connotations typically associated with xenomelia, also in the present sample. These may have their roots in the proximity of primary Somatosensory Cortex for leg representation, whose surface area was reduced in the participants with xenomelia, with that of the genitals. Alternatively, the spatial adjacency of Secondary Somatosensory Cortex for leg representation and the anterior insula, the latter known to mediate sexual arousal beyond that induced by direct tactile stimulation of the genital area, might play a role. Although the right hemisphere regions of significant neuroarchitectural correlates of xenomelia are part of a network reportedly subserving body ownership, it remains unclear whether the structural alterations are the cause or rather the consequence of the long-standing and pervasive mismatch between body and self. * Abbreviations : SI : primary Somatosensory Cortex SII : Secondary Somatosensory Cortex

Leeanne M Carey - One of the best experts on this subject based on the ideXlab platform.

  • activation of bilateral Secondary Somatosensory Cortex with right hand touch stimulation a meta analysis of functional neuroimaging studies
    Frontiers in Neurology, 2019
    Co-Authors: Gemma Lamp, Peter Goodin, Susan Palmer, Essie Low, Ayla Barutchu, Leeanne M Carey
    Abstract:

    Background: Brain regions involved in processing Somatosensory information have been well documented through lesion, post-mortem, animal, and more recently, structural and functional neuroimaging studies. Functional neuroimaging studies characterize brain activation related to Somatosensory processing; yet a meta-analysis synthesis of these findings is currently lacking and in-depth knowledge of the regions involved in Somatosensory-related tasks may also be confounded by motor influences. Objectives: Our Activation Likelihood Estimate (ALE) meta-analysis sought to quantify brain regions that are involved in the tactile processing of the right (RH) and left hands (LH) separately, with the exclusion of motor related activity. Methods: The majority of studies (n=41) measured activation associated with RH tactile stimulation. RH activation studies were grouped into those which conducted whole-brain analyses (n=29) and those which examined specific regions of interest (ROI; n=12). Few studies examined LH activation, though all were whole-brain studies (N=7). Results: Meta-analysis of brain activation associated with RH tactile stimulation (whole-brain studies) revealed large clusters of activation in the left primary Somatosensory Cortex (S1) and bilaterally in the Secondary Somatosensory Cortex (S2; including parietal operculum) and supramarginal gyrus (SMG), as well as the left anterior cingulate. Comparison between findings from RH whole-brain and ROI studies revealed activation as expected, but restricted primarily to S1 and S2 regions. Further, preliminary analyses of LH stimulation studies only, revealed two small clusters within the right S1 and S2 regions, likely limited due to the small number of studies. Contrast analyses revealed the one area of overlap for RH and LH, was right Secondary Somatosensory region. Conclusions: Findings from the whole-brain meta-analysis of right hand tactile stimulation emphasize the importance of taking into consideration bilateral activation, particularly in Secondary Somatosensory Cortex. Further, the right parietal operculum/S2 region was commonly activated for right and left hand tactile stimulation, suggesting a lateralized pattern of Somatosensory activation in right Secondary Somatosensory region. Implications for further research and for possible differences in right and left hemispheric stroke lesions are discussed.

Alfons Schnitzler - One of the best experts on this subject based on the ideXlab platform.

  • fluctuations of prestimulus oscillatory power predict subjective perception of tactile simultaneity
    Cerebral Cortex, 2012
    Co-Authors: Joachim Lange, Johanna Halacz, Hanneke Van Dijk, Nina Kahlbrock, Alfons Schnitzler
    Abstract:

    Oscillatory activity is modulated by sensory stimulation but can also fluctuate in the absence of sensory input. Recent studies have demonstrated that such fluctuations of oscillatory activity can have substantial influence on the perception of subsequent stimuli. In the present study, we employed a simultaneity task in the Somatosensory domain to study the role of prestimulus oscillatory activity on the temporal perception of 2 events. Subjects received electrical stimulations of the left and right index finger with varying stimulus onset asynchronies (SOAs) and reported their subjective perception of simultaneity, while brain activity was recorded with magnetoencephalography. With intermediate SOAs (30 and 45 ms), subjects frequently misperceived the stimulation as simultaneously. We compared neuronal oscillatory power in these conditions and found that power in the high beta band (∼20 to 40 Hz) in primary and Secondary Somatosensory Cortex prior to the electrical stimulation predicted subjects' reports of simultaneity. Additionally, prestimulus alpha-band power influenced perception in the condition SOA 45 ms. Our results indicate that fluctuations of ongoing oscillatory activity in the beta and alpha bands shape subjective perception of physically identical stimulation.

  • differential coding of pain intensity in the human primary and Secondary Somatosensory Cortex
    Journal of Neurophysiology, 2001
    Co-Authors: Lars Timmermann, Markus Ploner, Katrin Haucke, Frank Schmitz, Rudiger Baltissen, Alfons Schnitzler
    Abstract:

    The primary (SI) and Secondary (SII) Somatosensory cortices have been shown to participate in human pain processing. However, in humans it is unclear how SI and SII contribute to the encoding of no...

  • somatic and limbic Cortex activation in esophageal distention a functional imaging study
    Annals of Neurology, 1998
    Co-Authors: Ferdinand Binkofski, Alfons Schnitzler, P Enck, T Frieling, Stefan Posse, R J Seitz, H J Freund
    Abstract:

    Little is known about the cerebral representations of visceral sensations in humans. Using functional magnetic resonance imaging (fMRI), we mapped the cortical areas of the human brain that were activated by mechanical stimulation of the esophagus in 5 healthy volunteers. Stimulation probes were placed into the distal part of the esophagus and inflated to produce a local distention. The cerebral activation pattern was related to the strength and quality of the stimulus. The weakest stimulus accompanied by a well-localized albeit weak retrosternal sensation activated only the parietal opercular cortices, probably including the Secondary Somatosensory Cortex (SII). Additional activation of the primary sensorimotor Cortex (SI) at the level of the face and mouth representation as well as of the right premotor Cortex was found during repetitive distention of the esophagus at 0.5 Hz. Repetitive stimulation at 1 Hz additionally activated the insula bilaterally. The strongest distention stimulus, which caused a painful retrosternal sensation, resulted in an activation of the anterior cingulate Cortex. Our findings demonstrate that SII is the primary cortical target of visceral afferents originating in the esophagus. Limbic structures become engaged when the visceral sensation is unpleasant or painful.