FIG. 1.

Extracellular field potentials recorded in LGN evoked by optic tract stimulation. A and B: examples of field potentials recorded before and after the bath application of AMPA antagonist CNQX (A) or the L-type channel blocker nitrendipine (B). After 5 min, CNQX reduced the field potential to 61% of its baseline amplitude and after 10 min the response was completely abolished. By 20 min after washout, the field response was restored to 46% of its baseline amplitude. The application of nitrendipine had no effect on synaptic responses in LGN (see also Fig. 3). After 15–30 min responses were similar (97–99%) to baseline measures. C: examples of field responses recorded in normal ACSF from a single animal at P3. The corresponding amplitude × time plot (below) reflects an averaged (mean ± SE) response measured every 30 s over a 7.5-min time interval. Amplitude measurements are depicted as a percentage of the response measured during the first 7.5 min. LGN, lateral geniculate nucleus; AMPA, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid; CNQX, 6-cyano-7-nitroquinoxaline-2,3-dione; ACSF, artificial cerebrospinal fluid; P3, postnatal day 3.