A NOVEL THERMAL CONFLICT TASK TO INVESTIGATE APPROACH-AVOIDANCE BEHAVIOR FOLLOWING SUPPRESSION OF ADULT NEUROGENESIS

When difficult decisions must be made, the hippocampus contributes to behavioral conflict resolution by modulating the inhibition of dominant behavioral responses. The dentate gyrus, unique for its ability to produce new neurons into adulthood, plays a key role in this process. However it remains unclear whether adult neurogenesis is directly involved in difficult decision-making, and which aspects may be affected by new neurons. Here, we introduce a novel behavioral task to examine the role of adult-born neurons in conflict-based decision-making following the suppression of neurogenesis male rats. Neurogenesis was eliminated by 8 weeks of oral valganciclovir treatment in transgenic animals expressing herpes simplex virus thymidine kinase (TK) under control of the GFAP promoter. Littermates lacking the transgene served as controls. In the cold suppressed feeding task, food-deprived animals were placed in an arena with cold (5°C), neutral (20°C), and warm (35°C) zones. After a habituation session, food was fixed in the cold zone, compelling animals to choose between feeding and avoiding the aversive cold temperatures. During habituation, when food was absent, rats lacking neurogenesis traveled farther but exhibited similar temperature preferences to wild-type (WT) controls. However, when food was introduced in the cold quadrant, TKs spent less time in the cold zone and exhibited greater latencies to begin eating. These findings indicate that adult-born neurons influence decision-making in approach-avoidance conflicts and highlight the cold-suppressed feeding task as a valuable tool for investigating hippocampal neurogenesis. This research was supported by the Intramural Research Program of the NIMH (ZIAMH002784).