CAUDATE NEURONS RESPOND TO EXCITATORY AND INHIBITORY AMINO-ACIDS IN EARLY POSTNATAL PERIODS IN THE CAT

This study was designed to determine whether caudate neurons would respond to microphoretic application of glutamate and γ-aminobutyric acid (GABA) in early postnatal periods in the cat. Extracellular recordings were performed in 175 neurons in developing kittens and 114 neurons in adult cats. At the earliest ages tested (1-10 days), caudate cells were excited by microphoretic application of glutamate and were inhibited by application of GABA. The results also indicated that caudate units have lower response thresholds to application of glutamate and GABA in early postnatal periods than in later periods. Since previous findings indicated that synaptically mediated inhibitory potentials develop during later postnatal periods in the cat, the present findings suggest that receptors for GABA may be capable of functioning before presynaptic endings make operational contacts.