Action of urethane on dorsal lateral geniculate neurons

Light evoked neuronal responses of urethane anaesthetized rats were compared with those recorded in freely moving animals. The results demonstrate that urethane reduces the firing frequency, the response probability as well as the number of excitatory light evoked response phases. These changes are combined with a prolongation of the postexcitatory inhibitory phases. The latencies to diffuse flashes are increased in geniculate neuronal responses as well as in evoked potentials recorded from the visual cortex. A similar relation exists between diminution of late geniculate excitations and suppression of cortical photic afterdischarges.