ゼブラフィッシュの行動プログラムを引き出す神経回路の活性化
Imaging of the neural circuit activities during retrieval of behavioral program for active avoidance in zebrafish

We have previously shown that the central part of the dorsal pallium (Dc) in zebrafish has an important role in recalling the long-term memories of behavioral programs for an active avoidance paradigm. This result suggests that in zebrafish, the pallio-basal ganglia circuit is required for reinforcement learning. Meanwhile it has been reported that the medial part of dorsal pallium (Dm), a presumptive homolog of mammalian amygdala, is involved in retention of the long-term memory of learned fear. Although both two areas, Dc and Dm, are required to recall the active avoidance, there have been little reports how these two areas are functionally or anatomically related. In this study, using camk2a:GVP; UAS:G-CaMP7 line, we applied in vivo calcium imaging to the dorsal pallium to detect neural activities during retrieval of the behavioral program during the active avoidance. 24 hrs after last training, we measured florescence changes in response to LED stimulation as the CS presentation. In learner fish, a sequential neural activity of the caudal Dc (cDc), Dm and Dc was observed upon the LED stimulation. 30 min after last training, neural activity in the cDc was clearly detected, but not in the Dc. Next we trained fish with cued fear conditioning. 24 hrs after, the neural activities in the cDc and Dm were observed and that in the Dc was reduced. These results suggest that the neural active pattern of cDc, Dm and Dc in learner fish are organized after 24 hr after last training, and that neural activity of the Dc is involved in a recall of the remote memory of adaptive behavioral paradigm. Now we investigate a correlation of the neural activations among these three areas during a memory retrieval.