Abstract
A number of lateral geniculate neurons are excited by a volley delivered to either one or the other optic nerve and the resulting excitation is inhibited by stimuli to the other optic nerve. In this report, the distribution of the binocularly interacting (BI) neurons in the three cell laminae A, Al and B of the geniculate nucleus was studied in the cat anesthetized with a chloraloseurethane mixture. Unit discharges of the geniculate neurons were explored with stainless-steel microelectrodes. The neuron responded with an action potential to a volley to either one of the two optic nerves. In some of the neurons, a conditioning volley delivered to the optic nerve inhibited spike generation of the neuron excited by the test volley. The conditioning volley itself evoked no spike in the neuron but produced inhibition. This identified it as a BI neuron. The recording sites of the geniculate neurons were marked by electrolytic deposition of iron and the marking sites were identified by the use of the Prussian blue reaction. Of a total of 169 geniculate neurons thus identified, 42% of the neurons situated in lamina A, 84% of the neurons in Al and 47% in B showed a binocular inhibitory interaction.
