Prior electrical stimulation of dorsal periaqueductal grey matter or deep layers of the superior colliculus sensitizes rats to anxiety-like behaviors in the elevated T-maze test.

Electrical stimulation of the dorsal periaqueductal grey matter (DPAG) and deep layers of the superior colliculus (DLSC) of the rat elicits anxiety-like reactions such as freezing and flight. The temporal course of the effects of the aversive electrical stimulation of the DPAG (5, 15 and 30 min afterward) and DLSC (5, 10 and 15 min afterward) on the defensive response of rats exposed to elevated T-maze were determined. The elevated T-maze generates two defensive behaviors, inhibitory avoidance and one-way escape, which have been related, respectively, to generalized anxiety and panic disorders.