Development of visual-stimulus reversal learning-memory in mice is dependent on social interaction

Flexible learning about visual stimuli and reward was investigated in male mice in terms of development, social stimulation, and memory. In a sucrose foraging task, mice learned that one of the two complex visual stimuli was correct (compound discrimination, CD), followed 1 day later by rule reversal (CD reversal, CDR). Socially reared (SR) mice aged 6-12 weeks were tested at one weekly age: while all ages had CDR > CD errors, CDR errors were low at week 6, possibly due to immature long-term memory. Next, effects of social condition and memory were investigated: SR and socially isolated (SI, weeks 5-8) mice were tested on same day CD-CDR (working memory) or consecutive day CD-CDR (long-term memory): in each condition, SR mice had CDR > CD errors; SI mice had this in working memory, but CDR = CD errors in long-term memory, possibly reflecting easier reversal due to the prolongation of immature long-term memory.