an active nervous process arising in the central nervous system and leading to the suppression or prevention of excitation. A distinction is made between postsynaptic inhibition, which involves the action of a specific mediator on the postsynaptic membrane of a neuron, and presynaptic inhibition, which is based on the depolarization of a presynaptic nerve ending at the point of contact with another axonal nerve ending. All types of inhibition occurring in conditioned reflex activity are regarded as forms of central inhibition.