LONG-TERM POTENTIATION IN THE AUDITORY-CORTEX OF ADULT-RATS

Long-term potentiation (LTP) in the auditory cortex was studied in sli ces obtained from adult rats. White matter stimulation produced field potentials in layers II/III, which were composed of two negative waves followed by a slow positivity. The second negative and third positive waves were blocked by a low Ca2+(0.48 mM) medium or by 6-cyano-7-nitr oquinoxaline-2,3-dione (CNQX, 10 mu M), while the first negativity unc hanged. D-2-amino-5-phosphonovalerate (D-AP5, 50 mu M) showed no clear effect on the held potentials. Tetanic stimulation of the white matte r produced potentiation in the second negativity, and the potentiation was maintained for at least 30 min. D-AP5 blocked this potentiation c ompletely. These data indicate that LTP is evoked by activation of N-m ethyl-D-aspartate (NMDA) receptors in the auditory cortex of adult rat s.