Inhibitory mechanisms within the receptive fields of the lateral geniculate body of the cat.

The spatiotemporal organization of receptive fields (RF) of neurons in lateral geniculate body (LGB) was analyzed using several experimental methods. The stimulation of the RF by two separate spots showed largely extended inhibitory field overlapping also the central region. The increase of light-adaptation or barbiturate anesthesia levels enhanced the effectiveness of RF inhibitory surround in qualitatively different manner. The correlated neurons pairs were found, showing the reciprocal arrangement of inhibitory and excitatory areas of their RFs. It was possible to identify some of these pairs as consisting of relay cell and intergeniculate interneuron. The neurons from perigeniculate nucleus were also investigated. They had a synaptic input from the retina and were not activated antidromically from the visual cortex. Their RFs were large with non-concentric ON-OFF type of organization. Both types of geniculate interneurons were used to propose a functional model of LGB circuitry reviewing the data of all presented experiments.