A comparison of receptive field properties of vibrissa neurons between the rat thalamic reticular and ventro-basal nuclei.

Response properties of vibrissa-responding neurons in the somatosensory part of the rat thalamic reticular nucleus (S-TR) and ventro-basal complex (VB) were studied. Receptive field size was approximately the same between S-TR and VB neurons, i.e. most of the neurons were driven from only single vibrissa. On the other hand, there was a noticeable difference in direction sensitivity. VB neurons generally had a preference for a particular direction of vibrissa deflection; but most of the S-TR neurons responded equally well to all directions. In addition to the neurons showing excitatory responses, there were the small number of VB neurons which had exclusively inhibitory receptive fields. Response latencies of S-TR neurons to electrical stimulation of the medial lemniscus were longer by 0.9 ms on the average than those of VB neurons, indicating that the former neurons were driven monosynaptically by the latter.