My research examines how simple neuronal networks produce different behaviors and also how neuronal networks are altered with the formation of memories. To accomplish this, I perform large scale voltage-sensitive dye (VSD) imaging of neuronal populations in the central ganglia of the gastropod mollusk Tritonia diomedea that produce escape swimming and crawling behaviors. VSD imaging combined with Independent Component Analysis (ICA) allows for the simultaneous monitoring of dozens to hundreds of neurons with single-cell, sub-millisecond resolution. VSD imaging has revealed the presence of a class of neurons that participate in the escape swim network in a surprisingly unreliable manner, and optical data have also revealed a novel population of multifunctional swim/crawl motor neurons. Additionally, I am examining how neuronal networks can be reconfigured with the formation of simple types of non-associative learning such as sensitization and habituation.
VSD imaging combined with ICA allows us to monitor large numbers of neurons during different fictive motor programs. Above the activity of 34 Tritonia pedal ganglion neurons is shown during the sequential escape swimming and crawling motor programs elicited by a stimulus given to pedal nerve 3 (arrow).
To address plasticity at the level of single neurons/synapses, I use single neuron calcium imaging and electrophysiological techniques to examine the modulatory effects serotonergic neurons on calcium signaling at identified synapses. I believe that studies of network structure and plasticity at both the network level and at the single synapse level will lead to important discoveries concerning how nervous systems operate and encode memories.
Stimulation of the serotonergic modulatory neuron DSI enhances spike-evoked Ca2+ entry into the distal neurites of CPG neuron C2.