Functional Connectivity in the Brain of C. elegans

Abstract

Constructing a functional connectome of the brain has the potential to advance how faithful simulations are to the natural response of the system to perturbations because it provides integral information about dynamics in addition to the anatomical classification of connections between neurons. The nematode Caenorhabditis elegans provides a unique opportunity to investigate functional connectivity because of its compact, fully mapped nervous system of only 302 neurons. The existence of an anatomical connectome provides preliminary information for examining the dynamics of specific connections. This thesis investigates an approach to describing the dynamics of neural activity through expressing the response of neurons to a stimulus in terms of Green's functions and then applies that model to experimental data collected through single-neuron optogenetic stimulation. Through experiments we stimulated the I2 pharyngeal interneuron, taking advantage of its native photosensitivity, and recorded the response of surrounding neurons. Examining the response of surrounding neurons, we find consistent response of I1, another pharyngeal interneuron that is connected to I2 via gap junctions. Through fitting the response of the I1 neuron to stimulating I2, we confirm the validity of the proposed transfer function, a single exponential decay, describing signal propagation through gap junctions.