1:国立遺伝研個体遺伝初期発生 / National Institute of Genetics, Japan
The visual system plays a major role in food/prey recognition in diurnal animals. The food intake is regulated by the hypothalamus. Despite the importance of vision in feeding behavior, whether and how visual information of prey is conveyed to the hypothalamic feeding center is largely unknown. We address this question using zebrafish as a model animal, which has a highly developed visual system and shows vision-dependent behaviors, including visually-guided prey capture behavior. Neuronal activity in specific populations of cells can be monitored with a genetically encoded calcium probe, GCaMP using Gal4-UAS system. In our previous study, neuronal activity during visual perception of prey were observed on a visuotopic map of the optic tectum, corresponding to the prey location in the visual field. In this study, we explore the brain to identify neuronal activity, outside the visuotopic map, that is related to prey recognition. Real-time imaging of neuronal activity using freely-behaving and constrained zebrafish revealed activation of the hypothalamic feeding center upon recognition of prey or prey-like visual stimuli. Furthermore, we identified prey detector neurons in the pretectal area that projected to the hypothalamic feeding center. Ablation of the pretecto-hypothalamic circuit abolished prey capture behavior. Taken together, these results suggest that the pretecto-hypothalamic pathway plays a crucial role for conveying visual information to the feeding center. Thus, this pathway possibly converts visual food/prey detection into feeding motivation in zebrafish.