Cholinesterase levels and operant extinction.

Abstract

Extinction of an operant [conditional reflex] CR was analyzed for groups of rats in which the cholinesterase (ChE) activity of various tissues had been reduced. The reduction of ChE activity throughout S''s tissues resulted in a significant change in resistance to extinction. Selective reduction of ChE in the [central nervous system] CNS resulted in little change in extinction responding. When activity levels of ChE were varied systematically in brain and muscle, a reduction to 40% ChE activity levels was required to produce changes in extinction. Parameters of these effects are given for Ss with whole body as against Ss with only a selective reduction of brain ChE activity.