Neurons in cat lateral geniculate nucleus that concentrate exogenous [3H]-gamma-aminobutyric acid (GABA)

About one-quarter of the neurons in the A-laminae of the cat lateral geniculate selectively accumulate exogenous [3H]-gamma-aminobutyric acid (GABA), its analog, [3H]-2,4-diaminobutyric acid (DABA), and the GABA agonist, [3H] muscimol. These neurons are small (12-18 micrometers diameter) and lack a laminar body, which suggests that they correspond to the class III cell identified in Golgi material. GABA and DABA are also accumulated by F-terminals which are post-synaptic to retinal terminals and presynaptic to relay cell dendrites. It is suggested that GABA may be the transmitter for these small neurons which appear to mediate by means of local circuits a feed-forward inhibition onto the relay cells.