Topic
Somatosensory system
About: Somatosensory system is a research topic. Over the lifetime, 6371 publications have been published within this topic receiving 316900 citations.
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TL;DR: It is suggested that brain may respond to sudden increases in energy demand in part by rapid glycolytic metabolism of glycogen, as cerebral glycogen is restricted primarily to glia, and support a close coupling of glial energy metabolism with neuronal activity.
234 citations
TL;DR: Thalamic reorganization demonstrates that peripheral sensory deprivation may induce immediate plastic changes at multiple levels of the somatosensory system, and suggests a disruption of the normal dynamic equilibrium between multiple ascending and descending influences on the VPM.
Abstract: PERIPHERAL sensory deprivation induces reorganization within the somatosensory cortex of adult animals1-6. Although most studies have focused on the somatosensory cortex1–6, changes at subcortical levels (for example the thalamus) could also play a fundamental role in sensory plasticity7–11. To investigate this, we made chronic simultaneous recordings of large numbers of single neurons across the ventral posterior medial thalamus (VPM) in adult rats. This allowed a continuous and quantitative evaluation of the receptive fields of the same sample of single VPM neurons per animal, before and after sensory deprivation. Local anaesthesia in the face induced an immediate and reversible reorganization of a large portion of the VPM map. This differentially affected the short latency (4–6 ms) responses (SLRs) and long latency (15–25 ms) responses (LLRs) of single VPM neurons. The SLRs and LLRs normally define spatiotemporally complex receptive fields in the VPM12. Here we report that 73% of single neurons whose original receptive fields included the anaesthetized zone showed immediate unmasking of SLRs in response to stimulation of adjacent cutaneous regions, and/or loss of SLRs with preservation or enhancement of LLRs in response to stimulation of regions just surrounding the anaesthetized zone. This thalamic reorganization demonstrates that peripheral sensory deprivation may induce immediate plastic changes at multiple levels of the somatosensory system. Further, its spatiotemporally complex character suggests a disruption of the normal dynamic equilibrium between multiple ascending and descending influences on the VPM.
233 citations
TL;DR: It is found that genetic ablation of CGRPα-expressing sensory neurons reduced sensitivity to noxious heat, capsaicin, and itch and impaired thermoregulation but did not impair mechanosensation or β-alanine itch-stimuli associated with nonpeptidergic sensory neurons.
233 citations
TL;DR: A descending disynaptic inhibitory circuit that facilitates mechanical pain, is engaged during stress, and could be targeted to establish higher pain thresholds is uncovered.
230 citations
TL;DR: The distribution of calcitonin‐gene‐related peptide (CGRP) immunoreactivity (IR) was studied in peripheral tissues of rats to evaluate the ganglionic origin, somatosensory nature, and anatomic relations of this thin‐axon population with particular emphasis on possible nociceptive roles.
Abstract: The distribution of calcitonin-gene-related peptide (CGRP) immunoreactivity (IR) was studied in peripheral tissues of rats. The ganglionic origin, somatosensory nature, and anatomic relations of this thin-axon population were evaluated with particular emphasis on possible nociceptive roles. In animals untreated with colchicine, CGRP-IR is found in a vast proportion of small- and medium-diameter sensory ganglion cells that give rise to numerous thinly myelinated and unmyelinated axons that display CGRP-IR throughout the body.
The integumentary innervation consists, in part, of an extensive subpapillary network largely traced to dermal blood vessels, sweat glands, and “free” nerve endings, some of which are found within regions containing only mast cells, fibroblasts, and collagen. Dermal papillae contain CGRP-IR axons surrounding each vascular loop; other papillary axons end freely or occasionally surround Meissner corpuscles. Intraepithelial axons enter glabrous epidermal pegs, branching and exhibiting terminals throughout the stratum spinosum. A similar pattern is found in hairy skin with additional innervation entering the base and surrounding the lower third of each hair follicle, but apparently not supplying sebaceous glands and arrector pili muscle. Axons innervating nonkeratinized oral epithelium are similar or greater in number and distribution compared to epidermis, often with more extensive branching. The high density of intraepithelial CGRP-IR innervation does not appear to correlate with the sensitive mechanoreceptor-based increase in spatial sensory discriminative capacities in the distal portions of the limb.
In deep somatic tissues, CGRP-IR is principally related to vasculature and motor end plates of striated muscle, but there is an extensive network of thin axons within bone, principally in the periosteum, and focally in joint capsules, but not in relation to muscle spindles or tendon organs.
These findings, together with the distribution in cranial tissues described in an accompanying paper (Silverman and Kruger: J. Comp. Neurol. 280:303–330, '89), are considered in the context of a “noceffector” concept incorporating the efferent role of these sensory axons in various tissues. It is suggested that involvement in tissue maintenance and renewal during normal function, as well as following injury, may predominate over the relatively infrequent nociceptive role of this peptidergic sensory system.
230 citations