Influence of the somato-sensory stimulation on the visual receptive fields of suprageniculate and geniculate neurons in the chloralose anesthetized cat

Abstract

In dark adapted cat under deep chloralose anaesthesia, a somatic stimulation enlarges the size of the visual field of geniculate neurons, which then even discharge when a light stimulus is applied outside and near to the border of the visual field which has been outlined before without any somatic stimulation; moreover, the discharge rate upon visual stimulation inside the visual field also increases. This was also demonstrated in photopic conditions. Above the L G N, some units, which could be cells of the Nucleus Reticularis Thalami, exhibit unusual large receptive fields (30°–90°), and their responses appear to be fatigable. In a very few cases, paw stimulation enhances their visual response; but generally, after somatic stimulation, these units become unresponsive to the light stimulus.