Neural Network Underlying Photophobic Turning Behavior In Drosophila Larvae

How neural system can encode,store and extract information is a main question to be resolved in neuroscience.Neural circuit or network constructed by the complicated neural connection is responsible for our motor behaviors and psychological activities.One basic function of the nervous system is to help generate proper motor actions based on the cues coming from the external world.How information is processed in the central brain from the beginning of sensory input to the motor output?To answer this question,we use phototaxis behavior in Drosophila larva as working model to investigate neural circuit underlying sensory-motor transformation.Using this model,we explored the neural mechanism for how a larva exhibit proper turning behaviors when they meet light.We screened out a batch of larval central brain neurons based on phototactic behavior and calcium imaging.By combining optogenetics with calcium imaging experiment,we were able to construct a functional neural circuit including the neurons we newly identified and those identified in previous studies.By activating those neurons using optogenectic,or blocking their activity,and analyze the behavioral outputs in details with softwares,we assigned specific function in larval phototaxis to individual neurons in the circuit.Our work has elucidated the key disinhibitory neural mechanism responsible for larval turning response to light.We proved that the disinhibiton pathway is curcial for turning initiation upon light stimulation,and the restoration of inhibition at light off helps to secure the successful escape from light.