Spatiotemporal structure of somatosensory responses of many-neuron ensembles in the rat ventral posterior medial nucleus of the thalamus

摘要: Classically, the rat ventral posterior medial (VPM) nucleus of thalamus has been considered as a simple passive relay for single- whisker information to primary somatosensory cortex (SI). However, recent reports have suggested that VPM could contain much more coarsely coded and spatiotemporally complex representation pad. To address this possibility properly, we carried out chronic simultaneous recordings large numbers (up 23) single neurons, distributed across entire VPM, in both awake lightly anesthetized adult rats. Quantitative, computer-based reconstruction receptive fields (RFs) revealed neurons exhibit significant responses discrete stimulation many 20 whiskers (mean +/- SD RF size, 13.7 4.8 whiskers). By defining multiple response magnitude (RM) thresholds it was possible subdivide these RFs quantitatively into prominent center SD, 1.41 0.70 whiskers, RM > 95%) an excitatory surround 18 shifts occurred with largest our sample (17.2 2.4 On other hand, cells short-latency centered rostral had smallest (13.1 4.1 whiskers) usually did not time- dependent shifts. Multivariate analysis two groups C-->R shifting position (RP) cells, be statistically distinguished according combination three attributes (short-latency location, shift). “population maps” demonstrated “place” coding each involved distinct weighted contribution from proportion simultaneously recorded neurons.(ABSTRACT TRUNCATED AT 400 WORDS)