Somatosensory system

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

The contribution of NMDA and non-NMDA receptors to fast and slow transmission of sensory information in the rat SI barrel cortex.

Abstract: The main objective of this study was to establish the contribution of NMDA receptors to natural processing of somatosensory information within rat SI barrel cortex. Responses of 52 cells in layers I-IV of the rat barrel cortex were analyzed by PSTH (peristimulus histogram) analysis of evoked spikes in reply to brief deflections of the principal whisker in animals anesthetized with urethane. Short and longer peak latency responses within PSTHs were compared in the presence and absence of the specific NMDA and non-NMDA antagonists D(-)- 2-amino-5-phosphonovaleric acid and 6,7-dinitroquinoxaline-2,3-dione, which were administered locally to neurons by iontophoresis and additionally tested against their putative specific agonists, NMDA and quisqualate, respectively. The results suggest the following. (1) The generation of most spikes from cells in layers I-IV is dependent upon activation of NMDA receptors. However, NMDA receptors do not contribute to responses at very short latencies commensurate with monosynaptic thalamocortical relay for layer IV cells. These appear to be entirely mediated through non-NMDA receptors. (2) In the absence of transmission through NMDA receptors, non-NMDA receptors do not generate significant spike activity in later (10–100 msec latency) discharges. (3) NMDA receptor participation in first spike generation is directly dependent upon the latency of response of the cell to principal whisker deflection. (4) Latency of response, non-NMDA receptor-mediated spike generation and laminar location were powerfully covariant. (5) In addition, it was found that cells exhibiting short-duration spikes ( 80% dependent upon NMDA receptor action. It is concluded that most sensorially driven spike activity in layers I-IV is dependent upon NMDA receptor action. This appears to be enabled by contingent subthreshold depolarization largely through non-NMDA receptor action, whereas the earliest thalamocortical discharges are evoked solely through non-NMDA receptors.

A neuroanatomical basis for electroacupuncture to drive the vagal-adrenal axis.

Abstract: Somatosensory autonomic reflexes allow electroacupuncture stimulation (ES) to modulate body physiology at distant sites1–6 (for example, suppressing severe systemic inflammation6–9). Since the 1970s, an emerging organizational rule about these reflexes has been the presence of body-region specificity1–6. For example, ES at the hindlimb ST36 acupoint but not the abdominal ST25 acupoint can drive the vagal–adrenal anti-inflammatory axis in mice10,11. The neuroanatomical basis of this somatotopic organization is, however, unknown. Here we show that PROKR2Cre-marked sensory neurons, which innervate the deep hindlimb fascia (for example, the periosteum) but not abdominal fascia (for example, the peritoneum), are crucial for driving the vagal–adrenal axis. Low-intensity ES at the ST36 site in mice with ablated PROKR2Cre-marked sensory neurons failed to activate hindbrain vagal efferent neurons or to drive catecholamine release from adrenal glands. As a result, ES no longer suppressed systemic inflammation induced by bacterial endotoxins. By contrast, spinal sympathetic reflexes evoked by high-intensity ES at both ST25 and ST36 sites were unaffected. We also show that optogenetic stimulation of PROKR2Cre-marked nerve terminals through the ST36 site is sufficient to drive the vagal–adrenal axis but not sympathetic reflexes. Furthermore, the distribution patterns of PROKR2Cre nerve fibres can retrospectively predict body regions at which low-intensity ES will or will not effectively produce anti-inflammatory effects. Our studies provide a neuroanatomical basis for the selectivity and specificity of acupoints in driving specific autonomic pathways. Neuroanatomical findings demonstrate why electroactupuncture at only specific acupoints can drive the vagal–adrenal axis and treat inflammation in mice.

Proprioceptive activity in primate primary somatosensory cortex during active arm reaching movements

Abstract: 1. We studied the activity of 254 cells in the primary somatosensory cortex (SI) responding to inputs from peripheral proprioceptors in a variety of tasks requiring active reaching movements of the...