SPONTANEOUS EXPLORATION, RESPONSE PLUS POSITION LEARNING AND HIPPOCAMPAL MOSSY FIBER DISTRIBUTION - A CORRELATIONAL STUDY

Forty-eight mice from twelve isogenic groups were tested in two differ ent behavioral tests. The first test was a non-reinforced exploration of a Y-maze and the second was a response plus position learning follo wed by reversal learning in a T-maze. Behavioral results were correlat ed with the size of the area occupied by the various mossy fibre synap tic sub-fields in the hippocampus as revealed by Timm staining. The an alysis of results showed that mice with a large suprapyramidal mossy f ibre area tended to use a somewhat rigid motor response strategy durin g the initial exploration of the Y-maze, that they easily learned the response plus position task in the T-maze, but proved unable to quickl y inhibit that learned response during the reversal task. On the other hand, mice with a large intra-infrapyramidal synaptic field displayed greater ability to cope with a situation including novelty or constra int elements.