Meeting Abstract
Pavlovian conditioning, whereby an animal is trained to respond to a specific stimulus, is a powerful assay to study learning and memory. However, the majority of studies have focused on learning in isolated individuals. Moreover, these studies typically evaluate learning performance in binary groupings of successful or unsuccessful conditioned responses. In nature, many organisms occupy social groups and experience learning as a complex dynamic process that changes over time. Here, we designed a classical conditioning experiment to study the temporal progression of collective learning in adult zebrafish (Danio rerio, n=24 fish). Pairing a hydrodynamic stimulus (30 Hz vibrating dipole lasting 20 seconds) with food pellets (introduced 10 seconds after the stimulus onset), we trained fish to swim to a specific location to be fed. Experiments were conducted in a 10-gallon tank over a four week training period with three trials per day. For each trial we continuously filmed the activity for 5 minutes before and after the stimulus onset and recorded the number of fish in the feeding location every second. We found that the group size that successfully anticipated food after the stimulus onset increased gradually through the end of week three and then plateaued (n=22, Weibull function, R2 = 0.92). Interestingly, during the fourth week fish continued to learn, this time improving the precision of task execution by delaying their arrival to the food location after stimulus onset, and by departing from the food location more quickly after feeding. This demonstrates that zebrafish can learn the time interval between dipole onset and food introduction as well as the frequency of food introduction per trial. Our results suggest that collective learning during classical conditioning progresses in waves where animals are capable of forming complex level associations between stimuli over time.
