"ITR/AP(BIO):" Computational Analysis of Leech Swimming

Bryn Mawr College, Bryn Mawr PA

Investigators

Abstract

Many of the recent successes in behavioral neuroscience in both invertebrate and vertebrate systems have been attained by identifying individual neurons and assessing the role of each neuron in behavior by physiologically manipulating its activity level. There are, however, aspects of behavior that have not been adequately explained by this approach. In the case of the medicinal leech, the neuronal network controlling the initiation of swimming is well-understood at several levels, but this understanding does not account for the unpredictability with which stimulation of this pathway leads to swimming. Two possible reasons for this inadequacy will be addressed in this proposal: (1) neuronal networks provide static descriptions of the system and do not accurately reflect their dynamics, and (2) even simple behaviors are a function of large populations of neurons distributed throughout the nervous system. Because of the inherent complexity in the firing patterns of large populations of neurons, computational approaches are necessary for deciphering how the nervous system encodes behavior. This project will use linear statistical and spectral techniques and nonlinear techniques, in conjunction with discrete wavelet transforms, to test: (1) whether the 'state' or pattern of ongoing activity in the leech nerve cord prior to stimulation determines the likelihood that swimming will be elicited by a specific input, and (2) whether the neuronal control of swim initiation is a distributed property of the entire ventral nerve cord or is localizable to neuronal activity from specific regions of the leech nervous system. This project will provide research experiences for 10 undergraduate students from a primarily undergraduate women's college.