Neurobehavioral analysis of high-rate Sidman avoidance rat strain.

The neurobehavioral characteristics of the Tokai High-Avoider (THA) rats, which had an innate high-avoidance ability, were clarified by comparing with the Wistar rats from which the THA rat strain had been derived. THA rats performed superior learning and displayed small individual differences of learning performance, not only in the Sidman avoidance task, which had already been used in selective breeding, but also in two different tasks, namely water maze and two-way shuttle avoidance. No apparent difference was present in development, circadian rhythm, and open-field activity between the two strains. On the other hand, sensitivity of the THA rat to electric shock or to heat stress was less than that of the Wistar rat. From these results, it might be considered that the high and uniform avoidance performance exhibited in the THA rat was caused by an innately acquired ability but not by sensitivity to the shock or developmental differences.