Optimal Stimulus Parameters In Avoidance Conditioning Of Inbred Strains Of Mice.

Highly inbred mice of fast and slow conditioning strains (N = 228) were trained in avoidance conditioning and 180 were continued to extinction. The principal goal was to determine optimal stimulus conditions for fast learning, small variances, and maximal strain differences. Conclusions are: a) the major effect of change in CS-US and intertrial intervals occurs, respectively, for intervals less than 3 sec. and 60 sec.; b) change in amperage (150-400 pa) or voltage (250-400 v.) caused no significant differences; c) strain differences in extinction occurred after nearly optimal conditioning, and d) strain differences were altered considerably as stimulus conditions became optimal. Optimal levels of parameters are: 3 sec. CS-US interval, 120-sec. intertrial interval, and 400 v. (220 K ohm impedance circuit).