Long-term potentiation in the auditory cortex of adult rats

Long-term potentiation (LTP) in the auditory cortex was studied in slices 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-nitroquinoxaline-2,3-dione (CNQX, 10 microM), while the first negativity unchanged. D-2-amino-5-phosphonovalerate (D-AP5, 50 microM) showed no clear effect on the field potentials. Tetanic stimulation of the white matter produced potentiation in the second negativity, and the potentiation was maintained for at least 30 min. D-AP5 blocked this potentiation completely. These data indicate that LTP is evoked by activation of N-methyl-D-aspartate (NMDA) receptors in the auditory cortex of adult rats.