Effects of intracerebral implantation of corticosteroids on extinction of an avoidance response in rats

Intracerebral implantation of dexamethasone phosphate facilitated the rate of extinction of a pole jumping avoidance response when implanted into various areas in the median and posterior thalamus and in the ventriculus lateralis. Corticosterone, the rat's natural corticosteroid, also facilitated extinction of the avoidance response, but mainly if implanted in or near the nucleus parafascicularis. Implantations of either dexamethasone phosphate or corticosterone in other areas like hippocampus, nucleus septi lateralis, nucleus caudatus putamen, nucleus interstitialis striae terminalis and nucleus ventralis thalami did not result in a modification of the extinction rate.