Identified interneurons produce both primary afferent depolarization and presynaptic inhibition.

Crayfish interneurons were identified that appear to be directly responsible for presynaptic inhibition of primary afferent synapses during crayfish escape behavior. The interneurons are fired by a polysynaptic pathway triggered by the giant escape command axons. When directly stimulated, these interneurons produce short-latency, chloride-dependent primary afferent depolarizations and presynaptically inhibit primary afferent input to mechanosensory interneurons.