Search results for "somatosensory system"
showing 10 items of 174 documents
Contralateral hand anesthesia transiently improves poststroke sensory deficits.
2005
Objective To test a possible strategy to alleviate somatosensory deficits after stroke. Methods Here, we applied ischemic nerve block to the intact hand of patients with chronic stroke, which in healthy subjects elicits improvements in sensibility of the other hand. Results We found that sensibility in the affected hand improved with intact hand anesthesia, but not with intact foot anesthesia or no anesthesia. Interpretation We conclude that reduction of sensory input from the intact hand leads to site-specific improvements in tactile discriminative skills in the affected hand after the period of anesthesia, a potentially relevant finding in designing neurorehabilitative interventions. Ann …
Subcortical somatosensory evoked potentials after median nerve stimulation in children.
2000
We report our normative data of subcortical somatosensory evoked potentials (SEPs) after median nerve stimulation from a group of 55 children 4–15 years of age and 18 young adults 18–29 years of age. We recorded near-field potentials from the brachial plexus, the cervical cord and the somatosensory cortex. The far-field potentials P13, P14 and N18 from the brainstem were recorded from the scalp electrodes, when a non-cephalic reference at the contralateral Erb's point or an ear reference was used. The N9 (brachial plexus), N13a (dorsal horn), P13 (caudal medulla oblongata), N18 (medulla oblongata) and N20 (somatosensory cortex) were present in all subjects. The N13b (dorsal column near the …
Eye closure in darkness animates sensory systems.
2003
Single subject and group analyses (n = 12) showed that the eyes-open and eyes-closed states in complete darkness considerably and consistently differ in the patterns of associated brain activation in fMRI. During nonchanging external stimulation, ocular motor and attentional systems were activated when the eyes were open; the visual, somatosensory, vestibular, and auditory systems were activated when the eyes were closed. These data suggest that there are two different states of mental activity: with the eyes closed, an "interoceptive" state characterized by imagination and multisensory activity and with the eyes open, an "exteroceptive" state characterized by attention and ocular motor act…
Functional relevance of cross-modal plasticity in blind humans
1997
Functional imaging studies of people who were blind from an early age have revealed that their primary visual cortex can be activated by Braille reading and other tactile discrimination tasks1. Other studies have also shown that visual cortical areas can be activated by somatosensory input in blind subjects but not those with sight2,3,4,5,6,7. The significance of this cross-modal plasticity is unclear, however, as it is not known whether the visual cortex can process somatosensory information in a functionally relevant way. To address this issue, we used transcranial magnetic stimulation to disrupt the function of different cortical areas in people who were blind from an early age as they i…
Combined EEG and MEG analysis of early somatosensory evoked activity in children and adolescents with focal epilepsies
2006
Abstract Objective The study aimed to evaluate differences between EEG and MEG analysis of early somatosensory evoked activity in patients with focal epilepsies in localizing eloquent areas of the somatosensory cortex. Methods Twenty-five patients (12 male, 13 female; age 4–25 years, mean 11.7 years) were included. Syndromes were classified as symptomatic in 17, idiopathic in 2 and cryptogenic in 6 cases. 10 patients presented with malformations of cortical development (MCD). 122 channel MEG and simultaneous 33-channel EEG were recorded during tactile stimulation of the thumb (sampling rate 769 Hz, band-pass 0.3–260 Hz). Forty-four hemispheres were analyzed. Hemispheres were classified as t…
Sensory strategies of postural sway during quiet stance in patients with haemophilic arthropathy.
2017
Introduction: The sensory strategies of postural control in adult haemophilic arthropathy patients are still poorly understood. Aim: To determine sensorial posture-control strategies through postural sway frequency analysis when in a bipedal quiet stance with and without visual stimulus deprivation in healthy subjects and patients with haemophilic arthropathy. Secondarily, to determine the irregularity of postural balance control through sample entropy (SampEn). Methods: A triaxial accelerometer attached at the L3 level determined the displacement and acceleration of the centre of mass (DCoM and ACoM, respectively) under open-and closed-eyes conditions. Sensorial strategies were studied by …
Torsional eye movement responses to monaural and binaural galvanic vestibular stimulation: side-to-side asymmetries.
2003
Vestibular stimulation by head accelerations always involves multisensory activation of the vestibular, somatosensory, and visual systems. Over the past few years, galvanic vestibular stimulation (GVS) has become increasingly popular for testing vestibular function for clinical and research purposes. Although GVS provides a nonphysiological stimulation, it is more selective than natural head accelerations and is thus an attractive tool for such tests. Eye movement responses elicited by GVS mainly consist of torsional and horizontal components, as first described by Hitzig in 1871. Animal experiments have shown that GVS increases the vestibular afferent spike frequency at the cathodal site a…
Functional MRI of galvanic vestibular stimulation with alternating currents at different frequencies.
2004
Abstract Functional MRI was performed in 28 healthy volunteers to study the effects of galvanic vestibular stimulation with alternating currents (AC-GVS) of different frequencies on brain activation patterns. The aims of this study were (1) to identify specific areas within the vestibular cortical network that are involved in the processing of frequency-specific aspects by correlation analyses, (2) to determine the optimal frequency for stimulation of the vestibular system with respect to perception, and (3) to analyze whether different frequencies of AC-GVS are mediated in different cortical areas or different sites within the vestibular cortex. AC-GVS was performed using sinusoidal stimul…
Is somatosensory amplification a risk factor for an increased report of side effects? Reference data from the German general population
2015
Abstract Objective The study investigates the association between somatosensory amplification and the reporting of side effects. It establishes a German version of the Somatosensory Amplification Scale and examines its psychometric properties in a representative sample of the German population. Methods Sample size was 2.469, with 51% taking any medication. Participants answered the Somatosensory Amplification Scale, Generic Assessment of Side Effects Scale, and indicated whether they were taking any medication and the type of medication. Correlational analysis and binary logistic regression were performed. Results When examining a subsample reporting both medication intake and general bodil…
Differential effects on the laser evoked potential of selectively attending to pain localisation versus pain unpleasantness
2004
Abstract Objective : To determine the effects on the laser evoked potential (LEP) of selectively attending to affective (unpleasantness) versus sensory-discriminative (localisation) components of pain. Methods : LEPs, elicited by painful CO 2 laser stimulation of two areas of the right forearm, were recorded from 62 electrodes in 21 healthy volunteers, during three tasks that were matched for generalised attention: Localisation (report stimulus location), Unpleasantness (report stimulus unpleasantness), Control (report pain detection). LEP components are named by polarity, latency, and electrode. Results : N300-T7 peak amplitude was significantly greater during Localisation than Unpleasantn…