Personality Variation in Associative Learning and Memory Retention in Zebrafish (Danio rerio)

Animals differ in how they acquire and retain information, and modify their behavior while interacting with their environment. These differences have been linked to personality type, yet how personality type and sex influence reward-associated memory is not well understood. We investigated the effects of personality type, sex, days of conditioning, and food reward on learning and memory retention in zebrafish using the conditioned place preference paradigm. We conditioned zebrafish to associate a visual background with a food reward across eleven sessions and assessed memory recall seven days later by measuring duration, frequency of entry, and latency to first entry in the conditioned zone. We observed that bold fish had early conditioned zone engagement, whereas shy zebrafish gradually increased their behavior into the conditioned zone with repeated conditioning. With food reward, preference for the conditioned zone increased after 7 and 11 days post-conditioning relative to baseline. Seven days after the last conditioning with food reward, the preference for conditioned zone remained unchanged in shy fish. This suggests that shy fish retain the ability to recall the learned association for at least 7 days after conditioning. Overall, personality, food reward, and sex influence behavioral changes in food reward-associated cognition, with shy-treated males showing gradual increases in behavior into the conditioned zone. These findings suggest that personality and sex differences may depend on the nature and valence of the associative task to recall. Thus, this study emphasizes the importance of assessing memory retention alongside learning acquisition to understand the relationship between personality types and cognition.