Somatosensory system

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

Somatosensory areas in man activated by moving stimuli: cytoarchitectonic mapping and PET.

Abstract: This study was performed to identify neuronal populations in the somatosensory areas engaged in discrimination of moving stimuli on the skin. Changes in regional cerebral blood flow (rCBF) were measured with positron emission tomography (PET) and correlated with cytoarchitectonic sensorimotor areas 4a, 4p, 3a, 3b, and 1. Volunteers discriminated differences in the speed of a rotating brush stimulating the palmar surface. Discrimination of moving stimuli, contrasted to rest, increased the rCBF mainly in primary somatosensory (S1) area 1, but also in area 3b. The parietal operculum (PO) was activated bilaterally. We conclude that area 1 is the area in S1 which is mainly responding to discrimination of moving stimuli and that the PO contains several regions engaged in the discrimination of fast transient stimuli.

Generator mechanisms of giant somatosensory evoked potentials in cortical reflex myoclonus

Abstract: In order to clarify the generator mechanisms for giant cortical evoked potentials, scalp topogoraphies of somatosensory evoked potentials (SEPs) following various types of stimulation, including electriacal nerve trunk and finger stimulation and mechanical stimulation, were investigated in 5 patients with cortical reflex myoclonus. For SEPs evoked by median nerve stimulation, not only the P25 and N34 components in central and parietal regions but also N25 in the frontal region were markedly enlarged in each patient. Their scalp distributions were not significasntly different from those of normal subjects. P25 and N25, but not N34, were considerably attenuated by interfering tactile stimulation applied to the hand. The components corresponding to P25, N25 and N34 following electrical stimulation of the digital nerves as well as mechanical stimulation of the finger were also remarkably large and showed scalp distributions similar to those for median nerve SEPs. It is therefore concluded that the giant cortical SEPs of cortical reflex myoclonus are generated in those areas of the primary sensory cortex which generate normal SEPs, in response to an input, at least in part, from cutaneous afferents on the basis of an extremely enhanced cortical excitability.

Motor Cortex Broadly Engages Excitatory and Inhibitory Neurons in Somatosensory Barrel Cortex

Abstract: Anatomical studies have shown that primary somatosensory (S1) and primary motor (M1) cortices are reciprocally connected. The M1 to S1 projection is thought to represent a modulatory signal that conveys motor-related information to S1. Here, we investigated M1 synaptic inputs to S1 by injecting an AAV virus containing channelrhodopsin-2 and a fluorescent tag into M1. Consistent with previous results, we found labeling of M1 axons within S1 that was most robust in the deep layers and in L1. Labeling was sparse in L4 and was concentrated in the interbarrel septa, largely avoiding barrel centers. In S1, we recorded in vitro from regular-spiking excitatory neurons and fast-spiking and somatostatin-expressing inhibitory interneurons. All 3 cell types had a high probability of receiving direct excitatory M1 input. Both excitatory and inhibitory cells within L4 were the least likely to receive such input from M1. Disynaptic inhibition was observed frequently, indicating that M1 recruits substantial inhibition within S1. Additionally, a subpopulation of L6 regular-spiking excitatory neurons received exceptionally strong M1 input. Overall, our results suggest that activation of M1 evokes within S1 a bombardment of excitatory and inhibitory synaptic activity that could contribute in a layer-specific manner to state-dependent changes in S1.