The Experts below are selected from a list of 9957 Experts worldwide ranked by ideXlab platform
Yumi Maeda - One of the best experts on this subject based on the ideXlab platform.
-
rewiring the Primary Somatosensory Cortex in carpal tunnel syndrome with acupuncture
Brain, 2017Co-Authors: Yumi Maeda, Norman W Kettner, Stephen Cina, Cristina Malatesta, Jessica Gerber, Claire Mcmanus, Rebecca Ongsutherland, Pia Mezzacappa, Alexandra LibbyAbstract:: Carpal tunnel syndrome is the most common entrapment neuropathy, affecting the median nerve at the wrist. Acupuncture is a minimally-invasive and conservative therapeutic option, and while rooted in a complex practice ritual, acupuncture overlaps significantly with many conventional peripherally-focused neuromodulatory therapies. However, the neurophysiological mechanisms by which acupuncture impacts accepted subjective/psychological and objective/physiological outcomes are not well understood. Eligible patients (n = 80, 65 female, age: 49.3 ± 8.6 years) were enrolled and randomized into three intervention arms: (i) verum electro-acupuncture 'local' to the more affected hand; (ii) verum electro-acupuncture at 'distal' body sites, near the ankle contralesional to the more affected hand; and (iii) local sham electro-acupuncture using non-penetrating placebo needles. Acupuncture therapy was provided for 16 sessions over 8 weeks. Boston Carpal Tunnel Syndrome Questionnaire assessed pain and paraesthesia symptoms at baseline, following therapy and at 3-month follow-up. Nerve conduction studies assessing median nerve sensory latency and brain imaging data were acquired at baseline and following therapy. Functional magnetic resonance imaging assessed somatotopy in the Primary Somatosensory Cortex using vibrotactile stimulation over three digits (2, 3 and 5). While all three acupuncture interventions reduced symptom severity, verum (local and distal) acupuncture was superior to sham in producing improvements in neurophysiological outcomes, both local to the wrist (i.e. median sensory nerve conduction latency) and in the brain (i.e. digit 2/3 cortical separation distance). Moreover, greater improvement in second/third interdigit cortical separation distance following verum acupuncture predicted sustained improvements in symptom severity at 3-month follow-up. We further explored potential differential mechanisms of local versus distal acupuncture using diffusion tensor imaging of white matter microstructure adjacent to the Primary Somatosensory Cortex. Compared to healthy adults (n = 34, 28 female, 49.7 ± 9.9 years old), patients with carpal tunnel syndrome demonstrated increased fractional anisotropy in several regions and, for these regions we found that improvement in median nerve latency was associated with reduction of fractional anisotropy near (i) contralesional hand area following verum, but not sham, acupuncture; (ii) ipsilesional hand area following local, but not distal or sham, acupuncture; and (iii) ipsilesional leg area following distal, but not local or sham, acupuncture. As these Primary Somatosensory Cortex subregions are distinctly targeted by local versus distal acupuncture electrostimulation, acupuncture at local versus distal sites may improve median nerve function at the wrist by somatotopically distinct neuroplasticity in the Primary Somatosensory Cortex following therapy. Our study further suggests that improvements in Primary Somatosensory Cortex somatotopy can predict long-term clinical outcomes for carpal tunnel syndrome.
-
functional deficits in carpal tunnel syndrome reflect reorganization of Primary Somatosensory Cortex
Brain, 2014Co-Authors: Yumi Maeda, Norman W Kettner, Jameson K Holden, Stephen Cina, Cristina Malatesta, Jessica Gerber, Claire Mcmanus, Jaehyun Im, Alexandra LibbyAbstract:Carpal tunnel syndrome, a median nerve entrapment neuropathy, is characterized by sensorimotor deficits. Recent reports have shown that this syndrome is also characterized by functional and structural neuroplasticity in the Primary Somatosensory Cortex of the brain. However, the linkage between this neuroplasticity and the functional deficits in carpal tunnel syndrome is unknown. Sixty-three subjects with carpal tunnel syndrome aged 20–60 years and 28 age- and sex-matched healthy control subjects were evaluated with event-related functional magnetic resonance imaging at 3 T while vibrotactile stimulation was delivered to median nerve innervated (second and third) and ulnar nerve innervated (fifth) digits. For each subject, the interdigit cortical separation distance for each digit’s contralateral Primary Somatosensory Cortex representation was assessed. We also evaluated fine motor skill performance using a previously validated psychomotor performance test (maximum voluntary contraction and visuomotor pinch/release testing) and tactile discrimination capacity using a four-finger forced choice response test. These biobehavioural and clinical metrics were evaluated and correlated with the second/third interdigit cortical separation distance. Compared with healthy control subjects, subjects with carpal tunnel syndrome demonstrated reduced second/third interdigit cortical separation distance (P < 0.05) in contralateral Primary Somatosensory Cortex, corroborating our previous preliminary multi-modal neuroimaging findings. For psychomotor performance testing, subjects with carpal tunnel syndrome demonstrated reduced maximum voluntary contraction pinch strength (P < 0.01) and a reduced number of pinch/release cycles per second (P < 0.05). Additionally, for four-finger forced-choice testing, subjects with carpal tunnel syndrome demonstrated greater response time (P < 0.05), and reduced sensory discrimination accuracy (P < 0.001) for median nerve, but not ulnar nerve, innervated digits. Moreover, the second/third interdigit cortical separation distance was negatively correlated with paraesthesia severity (r = −0.31, P < 0.05), and number of pinch/release cycles (r = −0.31, P < 0.05), and positively correlated with the second and third digit sensory discrimination accuracy (r = 0.50, P < 0.05). Therefore, reduced second/third interdigit cortical separation distance in contralateral Primary Somatosensory Cortex was associated with worse symptomatology (particularly paraesthesia), reduced fine motor skill performance, and worse sensory discrimination accuracy for median nerve innervated digits. In conclusion, Primary Somatosensory Cortex neuroplasticity for median nerve innervated digits in carpal tunnel syndrome is indeed maladaptive and underlies the functional deficits seen in these patients.
Christoph Braun - One of the best experts on this subject based on the ideXlab platform.
-
the tactile window to consciousness is characterized by frequency specific integration and segregation of the Primary Somatosensory Cortex
Scientific Reports, 2016Co-Authors: Julia Frey, Christoph Braun, Philipp Ruhnau, Sabine Leske, Markus Siegel, Nathan WeiszAbstract:We recently proposed that besides levels of local cortical excitability, also distinct pre-stimulus network states (windows to consciousness) determine whether a near-threshold stimulus will be consciously perceived. In the present magnetoencephalography study, we scrutinised these pre-stimulus network states with a focus on the Primary Somatosensory Cortex. For this purpose participants performed a simple near-threshold tactile detection task. Confirming previous studies, we found reduced alpha and beta power in the Somatosensory region contralateral to stimulation prior to correct stimulus detection as compared to undetected stimuli, and stronger event-related responses following successful stimulus detection. As expected, using graph theoretical measures, we also observed modulated pre-stimulus network level integration. Specifically, the right Primary Somatosensory Cortex contralateral to stimulation showed an increased integration in the theta band, and additionally, a decreased integration in the beta band. Overall, these results underline the importance of network states for enabling conscious perception. Moreover, they indicate that also a reduction of irrelevant functional connections contributes to the window to consciousness by tuning pre-stimulus pathways of information flow.
-
early integration of bilateral touch in the Primary Somatosensory Cortex
Human Brain Mapping, 2015Co-Authors: Luigi Tamè, Francesco Pavani, Christos Papadelis, Alessandro Farne, Christoph BraunAbstract:Animal, as well as behavioural and neuroimaging studies in humans have documented inte- gration of bilateral tactile information at the level of Primary Somatosensory Cortex (SI). However, it is still debated whether integration in SI occurs early or late during tactile processing, and whether it is somatotopically organized. To address both the spatial and temporal aspects of bilateral tactile process- ing we used magnetoencephalography in a tactile repetition-suppression paradigm. We examined Somatosensory evoked-responses produced by probe stimuli preceded by an adaptor, as a function of the relative position of adaptor and probe (probe always at the left index finger; adaptor at the index or middle finger of the left or right hand) and as a function of the delay between adaptor and probe (0, 25, or 125 ms). Percentage of response-amplitude suppression was computed by comparing paired (adaptor 1probe) with single stimulations of adaptor and probe. Results show that response suppres- sion varies differentially in SI and SII as a function of both spatial and temporal features of the stimuli. Remarkably, repetition suppression of SI activity emerged early in time, regardless of whether the adaptor stimulus was presented on the same and the opposite body side with respect to the probe.
-
Effects of motor activity on the organization of Primary Somatosensory Cortex.
Neuroreport, 2006Co-Authors: Anja Wühle, Jasmin J. Fahlbusch, Christoph BraunAbstract:: Recent studies have shown that adaptation of representational maps within the Primary Somatosensory Cortex can be induced by task-related motor activity. Here, we explore the relationship between the complexity of the motor task and the extent of task-specific adaptation within the Primary Somatosensory Cortex. We hypothesized that the extent of adaptation increases with the complexity of the motor task. Using neuromagnetic source imaging based on electrical stimulation of the thumb and ring finger, we demonstrate that cortical finger representations are more distant during performance of the pinch finger grip than in a rest condition. Our data suggest that Somatosensory cortical maps undergo rapid modulation depending on the task-specific involvement of Somatosensory feedback in movements.
-
functional organization of Primary Somatosensory Cortex depends on the focus of attention
NeuroImage, 2002Co-Authors: Christoph Braun, Thomas Elbert, Niels Birbaumer, Monika Haug, Katja Wiech, Larry E RobertsAbstract:Abstract We used magnetic source imaging in human subjects to reveal within-subject variations of the homuncular hand representation within the Primary Somatosensory Cortex modulated by attention. In one condition subjects were trained to detect sequential leftward or rightward stimulus motion across the fingers of the left hand (“hand” condition) and in a different condition to detect stimulus motion at a specific finger on this hand (“finger” condition). Afferent input was controlled by applying exactly the same stimulus pattern to the digits in the two tasks. Segregation of the somatotopic hand representation (an increase in the distance between the representations of digits 2 and 5) was observed, commencing with the onset of practice, in the finger relative to the hand condition. Subsequent training in the hand and finger conditions with feedback for correctness did not modify segregation, indicating that segregation was a task effect and not a training effect. These findings indicate that the hand representation within the Primary Somatosensory Cortex is not statically fixed but is dynamically modulated by top-down mechanisms to support task requirements. A greater capacity for modulation of the functional cortical organization was positively correlated with superior learning and task performance.
-
extensive reorganization of Primary Somatosensory Cortex in chronic back pain patients
Neuroscience Letters, 1997Co-Authors: Herta Flor, Christoph Braun, Thomas Elbert, Niels BirbaumerAbstract:Abstract The hypothesis of reorganization of the Primary Somatosensory Cortex in states of chronic pain was assessed in 10 low back pain patients and nine matched healthy controls. Intracutaneous electric stimuli were applied to the left back and index finger at a standard, a non-painful and a painful intensity. Magnetic fields were recorded by a 37-channel BTi biomagnetometer from the hemisphere contralateral to the site of stimulation. The power of the early evoked magnetic field ( r =0.74). The maximum activity elicited in Primary Somatosensory Cortex was shifted more medially in the very chronic back pain subjects. These data suggest that chronic pain is accompanied by cortical reorganization and may serve an important function in the persistence of the pain experience.
Alexandra Libby - One of the best experts on this subject based on the ideXlab platform.
-
rewiring the Primary Somatosensory Cortex in carpal tunnel syndrome with acupuncture
Brain, 2017Co-Authors: Yumi Maeda, Norman W Kettner, Stephen Cina, Cristina Malatesta, Jessica Gerber, Claire Mcmanus, Rebecca Ongsutherland, Pia Mezzacappa, Alexandra LibbyAbstract:: Carpal tunnel syndrome is the most common entrapment neuropathy, affecting the median nerve at the wrist. Acupuncture is a minimally-invasive and conservative therapeutic option, and while rooted in a complex practice ritual, acupuncture overlaps significantly with many conventional peripherally-focused neuromodulatory therapies. However, the neurophysiological mechanisms by which acupuncture impacts accepted subjective/psychological and objective/physiological outcomes are not well understood. Eligible patients (n = 80, 65 female, age: 49.3 ± 8.6 years) were enrolled and randomized into three intervention arms: (i) verum electro-acupuncture 'local' to the more affected hand; (ii) verum electro-acupuncture at 'distal' body sites, near the ankle contralesional to the more affected hand; and (iii) local sham electro-acupuncture using non-penetrating placebo needles. Acupuncture therapy was provided for 16 sessions over 8 weeks. Boston Carpal Tunnel Syndrome Questionnaire assessed pain and paraesthesia symptoms at baseline, following therapy and at 3-month follow-up. Nerve conduction studies assessing median nerve sensory latency and brain imaging data were acquired at baseline and following therapy. Functional magnetic resonance imaging assessed somatotopy in the Primary Somatosensory Cortex using vibrotactile stimulation over three digits (2, 3 and 5). While all three acupuncture interventions reduced symptom severity, verum (local and distal) acupuncture was superior to sham in producing improvements in neurophysiological outcomes, both local to the wrist (i.e. median sensory nerve conduction latency) and in the brain (i.e. digit 2/3 cortical separation distance). Moreover, greater improvement in second/third interdigit cortical separation distance following verum acupuncture predicted sustained improvements in symptom severity at 3-month follow-up. We further explored potential differential mechanisms of local versus distal acupuncture using diffusion tensor imaging of white matter microstructure adjacent to the Primary Somatosensory Cortex. Compared to healthy adults (n = 34, 28 female, 49.7 ± 9.9 years old), patients with carpal tunnel syndrome demonstrated increased fractional anisotropy in several regions and, for these regions we found that improvement in median nerve latency was associated with reduction of fractional anisotropy near (i) contralesional hand area following verum, but not sham, acupuncture; (ii) ipsilesional hand area following local, but not distal or sham, acupuncture; and (iii) ipsilesional leg area following distal, but not local or sham, acupuncture. As these Primary Somatosensory Cortex subregions are distinctly targeted by local versus distal acupuncture electrostimulation, acupuncture at local versus distal sites may improve median nerve function at the wrist by somatotopically distinct neuroplasticity in the Primary Somatosensory Cortex following therapy. Our study further suggests that improvements in Primary Somatosensory Cortex somatotopy can predict long-term clinical outcomes for carpal tunnel syndrome.
-
functional deficits in carpal tunnel syndrome reflect reorganization of Primary Somatosensory Cortex
Brain, 2014Co-Authors: Yumi Maeda, Norman W Kettner, Jameson K Holden, Stephen Cina, Cristina Malatesta, Jessica Gerber, Claire Mcmanus, Jaehyun Im, Alexandra LibbyAbstract:Carpal tunnel syndrome, a median nerve entrapment neuropathy, is characterized by sensorimotor deficits. Recent reports have shown that this syndrome is also characterized by functional and structural neuroplasticity in the Primary Somatosensory Cortex of the brain. However, the linkage between this neuroplasticity and the functional deficits in carpal tunnel syndrome is unknown. Sixty-three subjects with carpal tunnel syndrome aged 20–60 years and 28 age- and sex-matched healthy control subjects were evaluated with event-related functional magnetic resonance imaging at 3 T while vibrotactile stimulation was delivered to median nerve innervated (second and third) and ulnar nerve innervated (fifth) digits. For each subject, the interdigit cortical separation distance for each digit’s contralateral Primary Somatosensory Cortex representation was assessed. We also evaluated fine motor skill performance using a previously validated psychomotor performance test (maximum voluntary contraction and visuomotor pinch/release testing) and tactile discrimination capacity using a four-finger forced choice response test. These biobehavioural and clinical metrics were evaluated and correlated with the second/third interdigit cortical separation distance. Compared with healthy control subjects, subjects with carpal tunnel syndrome demonstrated reduced second/third interdigit cortical separation distance (P < 0.05) in contralateral Primary Somatosensory Cortex, corroborating our previous preliminary multi-modal neuroimaging findings. For psychomotor performance testing, subjects with carpal tunnel syndrome demonstrated reduced maximum voluntary contraction pinch strength (P < 0.01) and a reduced number of pinch/release cycles per second (P < 0.05). Additionally, for four-finger forced-choice testing, subjects with carpal tunnel syndrome demonstrated greater response time (P < 0.05), and reduced sensory discrimination accuracy (P < 0.001) for median nerve, but not ulnar nerve, innervated digits. Moreover, the second/third interdigit cortical separation distance was negatively correlated with paraesthesia severity (r = −0.31, P < 0.05), and number of pinch/release cycles (r = −0.31, P < 0.05), and positively correlated with the second and third digit sensory discrimination accuracy (r = 0.50, P < 0.05). Therefore, reduced second/third interdigit cortical separation distance in contralateral Primary Somatosensory Cortex was associated with worse symptomatology (particularly paraesthesia), reduced fine motor skill performance, and worse sensory discrimination accuracy for median nerve innervated digits. In conclusion, Primary Somatosensory Cortex neuroplasticity for median nerve innervated digits in carpal tunnel syndrome is indeed maladaptive and underlies the functional deficits seen in these patients.
Miguel A. L. Nicolelis - One of the best experts on this subject based on the ideXlab platform.
-
cortical and thalamic contributions to response dynamics across layers of the Primary Somatosensory Cortex during tactile discrimination
Journal of Neurophysiology, 2015Co-Authors: Miguel Paisvieira, Carolina Kunicki, Pohe Tseng, Joel R Martin, Mikhail A Lebedev, Miguel A. L. NicolelisAbstract:Tactile information processing in the rodent Primary Somatosensory Cortex (S1) is layer specific and involves modulations from both thalamocortical and cortico-cortical loops. However, the extent to which these loops influence the dynamics of the Primary Somatosensory Cortex while animals execute tactile discrimination remains largely unknown. Here, we describe neural dynamics of S1 layers across the multiple epochs defining a tactile discrimination task. We observed that neuronal ensembles within different layers of the S1 Cortex exhibited significantly distinct neurophysiological properties, which constantly changed across the behavioral states that defined a tactile discrimination. Neural dynamics present in supragranular and granular layers generally matched the patterns observed in the ventral posterior medial nucleus of the thalamus (VPM), whereas the neural dynamics recorded from infragranular layers generally matched the patterns from the posterior nucleus of the thalamus (POM). Selective inactivation of contralateral S1 specifically switched infragranular neural dynamics from POM-like to those resembling VPM neurons. Meanwhile, ipsilateral M1 inactivation profoundly modulated the firing suppression observed in infragranular layers. This latter effect was counterbalanced by contralateral S1 block. Tactile stimulus encoding was layer specific and selectively affected by M1 or contralateral S1 inactivation. Lastly, causal information transfer occurred between all neurons in all S1 layers but was maximal from infragranular to the granular layer. These results suggest that tactile information processing in the S1 of awake behaving rodents is layer specific and state dependent and that its dynamics depend on the asynchronous convergence of modulations originating from ipsilateral M1 and contralateral S1.
-
Cortical and thalamic contributions to response dynamics across layers of the Primary Somatosensory Cortex during tactile discrimination
Journal of Neurophysiology, 2015Co-Authors: Miguel Pais-vieira, Carolina Kunicki, Pohe Tseng, Joel R Martin, Mikhail A Lebedev, Miguel A. L. NicolelisAbstract:Tactile information processing in the rodent Primary Somatosensory Cortex (S1) is layer specific and involves modulations from both thalamocortical and cortico-cortical loops. However, the extent t...
-
Heterogeneous Integration of Bilateral Whisker Signals by Neurons in Primary Somatosensory Cortex of Awake Rats
Journal of Neurophysiology, 2004Co-Authors: Michael C. Wiest, Nick Bentley, Miguel A. L. NicolelisAbstract:Bilateral single-unit recordings in Primary Somatosensory Cortex (S1) of anesthetized rats have revealed substantial cross talk between cortical hemispheres, suggesting the possibility that behavio...
-
Spatiotemporal Properties of Layer V Neurons of the Rat Primary Somatosensory Cortex
Cerebral Cortex, 1999Co-Authors: Asif A. Ghazanfar, Miguel A. L. NicolelisAbstract:Animals in their natural environments actively process spatiotemporally complex sensory signals in order to guide adaptive behavior. It therefore seems likely that the properties of both single neurons and neural ensembles should reflect the dynamic nature of such interactions. During exploratory behaviors, rats move their whiskers to actively discriminate between different tactile features. We investigated whether this dynamic sensory processing was reflected in the spatial and temporal properties of neurons in layer V of the ‘whisker area’ in the rat Primary Somatosensory Cortex. We found that the majority of layer V neurons had large (8.5 ± 4.9 whiskers) spatiotemporal receptive fields (i.e. individual cells responded best to different whiskers as a function of post-stimulus time), and that the excitatory responses of surround whiskers formed a spatial gradient of excitation that seemed to reflect the greater use of the ventral and caudal whiskers during natural behaviors. Analyses of ensembles of layer V neurons revealed that single-whisker stimuli activated a portion of layer V that extends well beyond a single cortical column (average of 5.6 barrel cortical columns). Based on these results, we conclude that the rat Primary Somatosensory Cortex does not appear to operate as a static decoder of tactile information. On the contrary, our data suggest that tactile processing in rats is likely to involve the on-going interactions between populations of broadly tuned neurons in the thalamocortical pathway.
Flavia Di Pietro - One of the best experts on this subject based on the ideXlab platform.
-
Primary Somatosensory Cortex function in complex regional pain syndrome a systematic review and meta analysis
The Journal of Pain, 2013Co-Authors: Flavia Di Pietro, James H Mcauley, Luke Parkitny, Martin Lotze, Benedict M Wand, Lorimer G Moseley, Tasha R StantonAbstract:That complex regional pain syndrome (CRPS) is associated with functional reorganization in the Primary Somatosensory Cortex (S1) is widely accepted and seldom questioned. Despite more than a decade of research, there has been no systematic review of the CRPS literature concerning the changes in S1 function, and therefore the extent of these changes is unclear. Here we conduct a systematic review and meta-analysis to quantify the spatial and temporal aspects of S1 function in CRPS. A comprehensive search strategy identified functional neuroimaging studies of S1 in CRPS. We adhered to a rigorous systematic review protocol when extracting data and appraising risk of bias. Outcomes were grouped into spatial representation; activation levels, including disinhibition; peak latency of activation; and glucose metabolism. Meta-analysis was conducted where possible. Fifteen studies were included, all investigating upper-extremity CRPS. In patients with CRPS, the S1 spatial representation of the affected hand is smaller than that of the unaffected hand and that of non-CRPS controls; however,thisevidencecomes fromonlyafewstudies. Thereisnodifferencein acti- vation, disinhibition, or latency of peripherally evoked S1 responses in CRPS. The risk of bias was high across studies, mainly from unclear sampling methods and unblinded analysis of outcomes. Perspective: The evidence for a difference in function of the Primary Somatosensory Cortex in CRPS compared with controls is clouded by high risk of bias and conflicting results, but reduced represen- tation size seems consistent.
