Both fast and slow relay cells in lateral geniculate nucleus of rabbits receive recurrent inhibition

Intracellular recordings from slow relay cells in the rabbit lateral geniculate nucleus demonstrated that the slow cells, just like the fast ones, receive a monosynaptic EPSP and a trisynaptic IPSP from the optic nerve. The IPSP is most likely mediated by interneurones activated by recurrent collaterals of the relay cell axon. In slow relay cells, both the EPSP and the IPSP from the optic nerve are brought about via the same group of slowly-conducting fibers. No mutual inhibition between the fast and the slow conducting system was observed in the rabbit lateral geniculate nucleus.