Advisor: Hang Lu, Ph.D. (Georgia Institute of Technology)
J. Brandon Dixon, Ph.D. (Georgia Institute of Technology)
Patrick T. McGrath, Ph.D. (Georgia Institute of Technology)
Simon Sponberg, Ph.D. (Georgia Institute of Technology)
Lena H. Ting, Ph.D. (Georgia Institute of Technology, Emory University)
Investigating the mechanosensory mechanisms of two unique neuron groups in C. elegans
Mechanosensation is the basis for touch, hearing, and balance. It plays a vital role in how we navigate and operate in the world. Environmental information is taken by sensory neurons and converted into electrochemical signals, which are then conveyed and processed within a network of neurons to produce a relevant behavioral response. Caenorhabditis elegans are a microscopic nematode with a simple nervous system used as a model organism to study neural circuits, including the mechanosensory circuit. Previous work has identified and characterized several components of the mechanosensory circuit in C. elegans, including the proteins that make up the mechanotransductory ion channel in gentle touch neurons: proteins from the DEG/ENaC family, which are conserved in humans. Some behavioral and neuronal responses to simple mechanical stimuli are also known. However, the sensory response to complex, dynamic stimuli, and the mechanotransduction elements associated with such a response are still unknown. Furthermore, an entirely different set of mechanosensory neurons, dopamine releasing neurons, are known to have a unique and interconnected function with the rest of the mechanosensory circuit. These neurons do not express DEG/ENaC proteins, but instead express TRP-4, another protein homologous to mechanosensory proteins in higher organisms. Little is known about how they function. This thesis will use microfluidic, optical, and genetic techniques to apply temporally and spatially dynamic stimuli to C. elegans and characterize their neuronal response. Mutants with defects in mechanotransduction channel proteins, or neurotransmission in the different mechanosensory neurons, will be tested in the same manner to determine how different mechanotransduction components contribute to the mechanosensory circuit, and to reveal how the two neuron types interact. Stimuli will also be delivered to freely moving wild type and mutant animals, and their behavior will be characterized to determine how downstream outputs are affected by sensory neuronal capability and specificity. This work will provide insights into the mechanisms by which sensory neurons sense and process information, and how different types of sensory neurons work together to better process sensory information and produce relevant behaviors.