AMO Special Seminar - September 7^th

David Biron

Univ. of Chicago

Quantitative descriptions of complex behavior

Abstract

The definition of behavior as the total motion of an animal hides great complexity. Precise measurements, relevant perturbations, and theoretical modeling are key for understanding the dynamics, function, and evolution of behavior. The first part of the talk will describe feeding behavior in the roundworm C. elegans. Worms exhibit bursty feeding dynamics, the function of which is unknown. Our central assumption is that food intake serves a dual purpose: to gather information about the environment as well as to ingest nutrients. We have developed methods for prolonged and precise measurement of feeding and characterized the observed dynamics. The resulting data drove a model which feasibly implements trade-offs between speed versus accuracy and exploration versus exploitation and predicts three regimes in responding to a dynamic environment.

The second part of the talk will focus on the most mysterious of all behaviors - sleep. The roles of sleep and the reasons for its universality remain controversial. The worm is the simplest model system in which such questions can be addressed and it shares many of the relevant mechanisms with more complex organisms. In particular, worms are an excellent model for the roles of sleep on the scale of cells and tissues. In all animals examined, sleep deprivation results in cellular “hardware malfunction”. On the organismal level this manifests as reduced performance of the tired animal. We have found similar effects in worms and extended them to a type of malfunction that was only hinted at previously. Interestingly, distinct types of damage are prominent in different tissues of tired worms. In addition to reducing performance of simple behavioral modalities, we found that tiredness can increase correlations between them. Therefore, sleep deprivation can be used simultaneously to examine the functions of sleep and the organization of composite behavioral patterns.

11:30 Drory Auditorium