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Somatosensory System

開催日 2014/9/13
時間 11:00 - 12:00
会場 Poster / Exhibition(Event Hall B)

Spatiotemporal dynamics of sensory processing in the rat vibrissa/barrel system

  • P3-153
  • 平井 大地 / Daichi Hirai:1 柴田 憲一 / Ken-ichi Shibata:1 金子 武嗣 / Takeshi Kaneko:1 古田 貴寛 / Takahiro Furuta:1 
  • 1:京都大学 / Dept Morphol Brain Sci, Grad Sch of Med, Kyoto Univ, Kyoto 

The vibrissa sensory system is a prevalent model of sensory processing. In the rodent trigeminal pathway, sensory inputs from the face are topographically mapped onto S1, and the orderly arrangement of whiskers on the snout is represented centrally by arrays of cellular aggregates referred to as barrels. By contrast, it is still now unclear how the central nervous system processes time in the early sensory processing. Temporal processing is required for simple sensory problems, such as interval, duration and motion discrimination. In this study, we examined how peripheral sensory input was encoded at cortical and subcortical levels of the vibrissa sensory system. Here, the juxtacellular labeling technique, which allows selective labeling and visualization of individual neurons in which electrophysiological data have been obtained, was applied to recordings. The vibrissa of rats was pushed mechanically by a piezo-driven vibrating insertion device, and neuronal responses to the whisker deflection were analyzed in waking head-restrained rats. As a result, this study revealed several new findings. (1) Subgroups of neurons in thalamic VPM nucleus showed onset and late (50ms-) responses to whisker deflection, and LTS bursts were hypothesized to be the origin of the late response. (2) The reticular nucleus (TRN) provides the only source of GABAergic projections to VPM, and whisker-responsive TRN neurons showed burst discharge in onset period, and the burst firing could induces to suppression prior to late response in VPM. (3) In contrast, less cortical neurons showed late response, and some corticothalamic projection neurons in the barrel column showed short latency sensory response as well as layer 4 neurons as dominant thalamic recipient. (4) By microinjection of GABA, we found effects of S1 inactivation to both onset and late responses of VPM and TRN neurons. In summary, the present experiments reveal that thalamic neurons have not simple relay function, and thalamic sustained spatiotemporal processing could be modulated by corticothalamic feedback during waking state. These observations suggest the thalamus gates peripheral sensory input based on the current cortical demand such as active sensation.

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