The visual system plays a major role in food/prey recognition in diurnal animals and the feeding behavior is regulated by the hypothalamus. In spite of 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 behaviors1, including visually-guided prey capture behavior2. Neuronal activity in specific populations of cells can be monitored with a genetically encoded calcium probe, GCaMP using Gal4-UAS system3. 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 field4. In this study, we explore the brain to identify neuronal activity, outside the visuotopic map, that is related to prey recognition. We perform real-time imaging of neuronal activity using freely-behaving or constrained zebrafish and demonstrate prey or prey-like visual stimuli activate the hypothalamic feeding center. Furthermore, we identify prey detector neurons in the pretectal area that project to the hypothalamic feeding center. Ablation of the pretecto-hypothalamic circuit abolishes prey capture behavior. Taken together, the results suggest that the pretecto-hypothalamic pathway plays a crucial role to convey visual information to the feeding center. Thus, this pathway possibly converts visual food detection into feeding motivation in zebrafish.
References
1. Muto et al. PLoS Genet. 2005;1(5):e66.
2. Muto and Kawakami. Front Neural Circuits. 2013;7:110.
3. Muto et al. Proc Natl Acad Sci U S A. 2011;108(13):5425-30.
4. Muto et al. Curr Biol. 2013;23(4):307-11.