Somatosensory system

About: Somatosensory system is a research topic. Over the lifetime, 6371 publications have been published within this topic receiving 316900 citations.

Somatosensory impairment after stroke: frequency of different deficits and their recovery

Abstract: Objective: To investigate the frequency of somatosensory impairment in stroke patients within different somatosensory modalities and different body areas, and their recovery.Design: Prospective observational study.Setting: Two stroke rehabilitation units.Subjects: Seventy patients with a first stroke (36 men, 34 women; average age, 71, SD 10.00 years; average time since stroke onset, 15 days) were assessed on admission and two, four and six months after stroke.Interventions: Not applicable.Main measure: Nottingham Sensory Assessment.Results: Somatosensory impairment was common after stroke; 7—53% had impaired tactile sensations, 31—89% impaired stereognosis, and 34—64% impaired proprioception. When comparing somatosensory modalities within body areas the kappa values were low (kappa values <0.54). Recovery occurred over time, though not significantly in lower limb tactile sensations. Stroke severity was the main factor influencing initial somatosensory impairment, but accounted for a small amount of the v...

Essential role of POU- domain factor Brn-3c in auditory and vestibular hair cell development (inner ear development)

Abstract: The Brn-3 subfamily of POU-domain tran- scription factor genes consists of three highly homologous members—Brn-3a, Brn-3b, and Brn-3c—that are expressed in sensory neurons and in a small number of brainstem nuclei. This paper describes the role of Brn-3c in auditory and vestibular system development. In the inner ear, the Brn-3c protein is found only in auditory and vestibular hair cells, and the Brn-3a and Brn-3b proteins are found only in subsets of spiral and vestibular ganglion neurons. Mice carrying a targeted deletion of the Brn-3c gene are deaf and have impaired balance. These defects ref lect a complete loss of auditory and vestibular hair cells during the late embryonic and early postnatal period and a secondary loss of spiral and vestibular ganglion neurons. Together with earlier work dem- onstrating a loss of trigeminal ganglion neurons and retinal ganglion cells in mice carrying targeted disruptions in the Brn-3a and Brn-3b genes, respectively, the Brn-3c phenotype reported here demonstrates that each of the Brn-3 genes plays distinctive roles in the somatosensory, visual, and auditoryy vestibular systems.

Cortical afferents and efferents of monkey postarcuate area: an anatomical and electrophysiological study.

Abstract: A study has been made of the corticocortical efferent and afferent connections of the posterior bank of the arcuate sulcus in the macaque monkey. The distribution of efferent projections to the primary motor cortex (MI) was studied by injecting three different fluorescent retrograde tracers into separate regions of MI. The resultant labeling showed a discrete and topographically organized projection: neurons lying below the inferior limb of the arcuate sulcus project into the MI face area, while neurons located in the posterior bank of the inferior limb of the arcuate sulcus and in the arcuate spur region project into the MI hand area. These findings were confirmed electrophysiologically by demonstrating that postarcuate neurons could only be activated antidromically by stimulation within restricted regions of MI. HRP injections within postarcuate cortex indicated that afferents to this region arise from a number of cortical areas. However, the largest numbers of labeled neurons were found in the posterior parietal cortex (area 7b; PF) and in the secondary somatosensory region (SII). Neurons in both 7b (PF) and SII could be antidromically activated by postarcuate stimulation. It was further shown that stimulation of area 7b (PF) gives rise to short-latency synaptic responses in postarcuate neurons, including some neurons with identified projections to MI. The results are discussed in relation to the possible function of the postarcuate region of the premotor cortex in the sensory guidance of movement.

Image-Guided Transcranial Focused Ultrasound Stimulates Human Primary Somatosensory Cortex

Abstract: Focused ultrasound (FUS) has recently been investigated as a new mode of non-invasive brain stimulation, which offers exquisite spatial resolution and depth control. We report on the elicitation of explicit somatosensory sensations as well as accompanying evoked electroencephalographic (EEG) potentials induced by FUS stimulation of the human somatosensory cortex. As guided by individual-specific neuroimage data, FUS was transcranially delivered to the hand somatosensory cortex among healthy volunteers. The sonication elicited transient tactile sensations on the hand area contralateral to the sonicated hemisphere, with anatomical specificity of up to a finger, while EEG recordings revealed the elicitation of sonication-specific evoked potentials. Retrospective numerical simulation of the acoustic propagation through the skull showed that a threshold of acoustic intensity may exist for successful cortical stimulation. The neurological and neuroradiological assessment before and after the sonication, along with strict safety considerations through the individual-specific estimation of effective acoustic intensity in situ and thermal effects, showed promising initial safety profile; however, equal/more rigorous precautionary procedures are advised for future studies. The transient and localized stimulation of the brain using image-guided transcranial FUS may serve as a novel tool for the non-invasive assessment and modification of region-specific brain function.