SUBSTRATE FOR RAPID FEEDFORWARD INHIBITION OF THE AUDITORY FOREBRAIN

A sizeable, feedforward, GABAergic projection exists from the inferior colliculus to the medial geniculate body in cats. We compared the dim ensions of GABA-immunoreactive and non-immunoreactive axons in the bra chium of the cat inferior colliculus, and demonstrate that GABA-immuno reactive axons are among the largest of brachial axons. We propose tha t, based on their large size, GABAegic tectothalamic axons provide a s ubstrate for rapid feedforward inhibition of geniculate neurons. (C) 1 997 Elsevier Science B.V.