LONG-TERM POTENTIATION OF NEUROTRANSMISSION IN THE INFERIOR COLLICULUS OF THE RAT

Postsynaptic field potential was elicited in the central nucleus of th e rat inferior colliculus after electrical stimulation to the lateral lemniscus. The inhibitory action of locally applied GABA on the potent ial was blocked by the systemic administration of picrotoxin, a GABA(A ) antagonist (2.5 mg/kg, i.p.). After the administration of picrotoxin , the tetanic stimulation of 50 Hz for 20 s increased the amplitude of the field potential to over 120% of the original level in 10 min; thi s was maintained for 40 min, and formed the long-term potentiation (LT P). The tetanic stimulation alone, however, failed to enhance the ampl itude. Thus, LTP was induced in the inferior colliculus only when GABA ergic action was depressed.