威廉希尔学术报告
题目：Using advanced calcium imaging to study the neural circuit dynamics underlying social interactions
演讲人：孙一
Research Specialist, 
GENIE Project, Janelia Research Campus, 
Howard Hughes Medical Institute, Ashburn, VA
时间：2017年10月26日（星期四）15：00-16：00
地点：新生物楼411
摘要：
Animals effortlessly recognize other members of their species, and some even customize their behavior towards different individuals, a remarkable feat that remains out of reach for artificial intelligence. During such interactions, animals often orient selectively towards a single conspecific, but how an individual is selected from many is poorly understood. Behavioral studies have shown state-dependent conspecific recognition and selection in Drosophila. Here I show that Drosophila ring neurons—central brain neurons implicated in navigation—display visual stimulus selection that could underlie such behaviors. By developing and applying in vivo two-color two-photon imaging with genetically encoded calcium indicators, I demonstrate that individual ring neurons inherit simple-cell-like receptive fields from their upstream partners. However, the appearance of a contralateral distractor suppressed responses to ipsilateral objects. The strength of this suppression depended on when and where the distractor was presented, an effect stronger in ring neurons than their upstream inputs. Contralateral suppression and history dependence, which were well captured by a circuit model with biphasic temporal filters and reciprocal inhibition, together enable dynamic stimulus selection. I hypothesize that such visual stimulus selection supports conspecific selection during social interactions. Conspecific interactions are multisensory and are modulated by an animal’s internal state, a complex process that likely involves interactions between multiple brain regions. To address just such a challenge, I developed whole-brain circuit tracing technology by combining a calcium integrator with optogenetics, and used the technique to trace a sensorimotor circuit that processes a food odor important for social interactions, phenylacetic acid. Taken together, my post-doctoral work lays the technical and biological foundations for understanding how multisensory integration and state modulation shape conspecific interactions. More broadly, my work highlights how the development of novel calcium and voltage imaging methods can help resolve the structure and function of neural circuits in vivo. In my own lab, I hope to also develop large-scale imaging methods for studying interactions between brain regions identified as being involved in social interactions by appropriate use of my calcium-integrator-based approach. The numerical simplicity of the fly brain can enable an understanding of neural circuits for social interactions before such large-scale network functions are understood in larger animals, and the underlying computational principles may guide brain-inspired computing and robotics. 
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