Genotype-dependent involvement of limbic areas in spatial learning and postlesion recovery.

Male C57BL/6 (C57) and DBA/2 (DBA) mice with hippocampal, amygdaloid, or sham lesions were tested in a radial eight-arm maze 1 or 4 weeks after surgery. The results show that the effect of the lesions varied according to the performance level of the strain considered. In the high-learner C57 strain, the two lesions impaired acquisition at both postlesion intervals. Conversely, in the low-learner DBA strain, only hippocampal lesions impaired acquisition 1 week but not 4 weeks after lesioning. It is hypothesized that if more limbic areas are involved in controlling spatial learning in C57 mice, these structures could be processing distinct but complementary memory attributes, thus contributing to a high baseline performance. This, however, also entails an increased sensitivity of C57 performance to brain damage with reduced possibilities of long-term recovery.