Fig. 4.

Integrated firing rate histograms of dorsal hippocampus CA₃ pyramidal neurons showing their responsiveness to microiontophoretic application of 5-HT and to intravenous injection of WAY 100635 (0.1 mg/kg) in rats receiving seven ECSs (A), in sham-operated rats (B), in rats treated with pertussis toxin (PTX) (C), and in rats receiving both 7-ECS and pertussis toxin treatments. These neurons were activated with a quisqualate ejection current of −1 to −3 nA. Note the altered firing activity after the administration of WAY 100635 only in rats receiving seven ECSs (A), and the altered suppressant effect of 5-HT in rats treated with pertussis toxin (C, D).