Fall 2015
Seminars are held on Tuesdays at 11:30AM in Cullimore Hall, Room 611, unless noted otherwise. For questions about the seminar schedule, please contact Casey Diekman.
Date: December 15, 2015
Speaker: Julijana Gjorgjieva
Volen Center for Complex Systems,
Brandeis University
Title: "Neural Circuits for Peristaltic Wave Propagation in Crawling Drosophila Larvae"
Abstract:
Drosophila larvae crawl by peristaltic waves of muscle contractions, which propagate along the animal body and involve the simultaneous contraction of the left and right side of each segment. Coordinated propagation of contraction does not require sensory input, suggesting that movement is generated by a central pattern generator (CPG). I will present a network model that recapitulates experimental crawling patterns based on segmentally repeated units of excitatory and inhibitory (E-I) neuronal populations coupled with immediate neighboring segments. I will then discuss plausible mechanisms for how functional network connectivity emerges during development to achieve robust crawling patterns. Activity-dependent mechanisms based on spontaneous activity generated in the developing network have been implicated in the tuning of connectivity. I examine two activity-dependent models which tune weak network connectivity: a Hebbian model, where coincident activity in neighboring populations strengthens connections between them; and a homeostatic model, where connections are homeostatically regulated to maintain a constant level of excitatory activity based on spontaneous input. I show that homeostatic mechanisms are more likely than Hebbian mechanisms to tune weak connectivity based on local activity patterns in a recurrent network for rhythm generation and propagation.