Direct evidence for recurrent inhibition in sliced brain preparation of the cat's visual cortex

To reveal the recurrent inhibitory circuit in the visual cortex, a depolarizing current was applied through a glass microelectrode to an impaled cell in an in vitro slice of the visual cortex obtained from a cat anesthetized with pentobarbital. The cell reported here produced inhibitory postsynaptic potentials (IPSPs) following single spikes or bursts of spikes which were elicited by intracellularly applied current. This observation indicates that IPSPs have been mediated by the recurrent inhibitory circuit via axon collaterals of the impaled cell.