Trace eyeblink conditioning in the freely moving rat: Optimizing the conditioning parameters

Trace eyeblink conditioning (EBC) parameters, with an airpuff unconditioned stimulus, were examined in male Fischer 344 X Brown Norway F1 rats. Integr ated electromyographic activity from the upper eyelid was recorded. An 8-kH z tone was superior to white noise as a conditioning stimulus. Rats trained with 30 or 50 trials per session showed similar learning. Reversal of envi ronmental lighting had no significant effect. Trace intervals of 0 and 250 ms yielded well-timed conditioned responses (CRs); intervals of 500 ms at m ore did not. These experiments provide parameters that reliably yield CRs a nd suggest limits on the temporal processing capabilities of the rat. EBC c an thus be used as part of a comprehensive test battery far learning and me mory in this species. Physiological recording and pharmacological manipulat ions may also be done easily. This combination of approaches should facilit ate a more complete understanding of learning mechanisms and age-related me mory impairments.