Fig. 4.

NMP activity is required for learning-induced behavioral improvement and the maintenance of normal visual avoidance behavior following enhanced visual training in tadpoles. (A) Illustration of the visual avoidance behavior in tadpoles. Animals make a sharp turn in their swimming trajectory when they encounter an approaching visual stimulus. The percentage of avoidance events out of the first 10 encounters is quantified as the avoidance index (AI) to evaluate the behavioral performance of the animals. (B) Experimental timeline for visual training and behavioral test schedule. Animals first received a ventricular injection of either BE or vehicle (Veh) and were tested 30 min later for baseline visual avoidance behavior performance (T1). Then, animals were subjected to 4 h of either visual training (VE) or ambient light and returned to their normal rearing conditions. Animals were tested again for avoidance behavior the next day (T2). (C) In the absence of VE, baseline behavioral performance was not affected by BE, n = 9 animal batches. (D) Following VE, vehicle-injected control animals improved their visual avoidance response. Inhibiting NMPs with BE not only completely blocked learning-induced behavioral improvement following VE but also caused a significant deterioration of the behavioral performance comparing with the pretraining baseline level. *P < 0.05 and **P < 0.01. Paired two-tailed Student’s t test, n = 6 animal batches.