Effects of meprobamate, chlordiazepoxide, diazepam, and sodium pentobarbital on visually evoked responses in the tectotegmental area of the rat.

-The effects of meprobamate, chlordiazepoxide, diazepam and sodium pentobarbital on sensory input to the boundary area between the dorsal midbrain tegmentum and ventral tectum of the rat have been investigated in order to find out whether effects obtained with these compounds in the hypothalamus can also be observed at the mesencephalic level. The following results have been obtained. (1) At a dose of 2"5 mg/kg i.p., chlordiazepoxide had no effect; at 5, 10, 15, and 20 mg/kg, this compound decreased the amplitude of the initial components of the visually evoked responses in the rat. There was an increased effect at higher doses.