Doctor of Philosophy, Miami University, 2023, Biology
Neuronal networks that produce oscillations underlie rhythmic motor behaviors (e.g., walking, chewing, and breathing), and complex behaviors (e.g., memory formation, decision making, and sensory processing). Oscillatory networks are subject to neuromodulation, promoting network flexibility, and ultimately enabling individuals to adapt to changes in their environment. Network flexibility includes reconfiguration, such as neuronal switching, in which neurons can change participation from one network into another, or into two distinct networks simultaneously, in response to neuromodulation. While modulation of synapses is an identified mechanism for both recruitment and coordination of a switching
neuron in a second network, it is unknown whether alternative mechanisms can be used. In this dissertation, I asked whether modulation of intrinsic membrane properties can serve as a mechanism for recruitment, while modulation of synapses enables coordination of switching neuron activity in a second network. To test this, I used the small, well-characterized feeding-related networks (pyloric [food filtering], ~1 Hz; gastric mill [food chewing], ~0.1 Hz) and identified modulatory inputs of the isolated stomatogastric nervous system of the crab, Cancer borealis. The modulatory projection neuron MCN5 releases the
neuropeptide Gly1-SIFamide, which increases pyloric frequency, activates the gastric mill rhythm, and switches the pyloric-only LPG neuron into dual pyloric plus gastric mill-timed bursting. Using bath application of the Gly1-SIFamide peptide, plus photoinactivation to eliminate activity of select neurons, I mimicked MCN5-elicited pyloric and gastric mill network activity. Then, using current clamp electrophysiology techniques, I examined whether the LPG neuron switch into the gastric mill network occurs due to Gly1-SIFamide modulation of LPG intrinsic membrane properties, and whether LPG gastric mill-timed bursting is regulated by pyloric and gastric mill network n (open full item for complete abstract)
Committee: Dawn Blitz (Advisor); Kathleen Killian (Committee Member); Anna Radke (Committee Member); Joseph Ransdell (Committee Member); Paul James (Committee Member)
Subjects: Biology; Neurosciences