Fig. 4.

Top, Injection of eticlopride during the day increases the b-wave amplitude. The figure plots the results of two experiments. After injection of eticlopride, the b-wave responses more than double within 30 min, reaching nearly the same amplitude recorded the previous night. Bottom, The b-wave amplitude remains relatively unchanged or decreases after injection of SCH 23390. The results of two experiments are plotted. The b-wave amplitude persists at low, daytime-like levels for up to 4 hr after injection.