Abstract
While a central pattern generator (CPG) can generate rhythmic motor output even in the absence of rhythmic input, in situ its output is continuously shaped by sensory feedback. This thesis investigates such modulation primarily in the context of consumption decisions, focusing on the neural dynamics leading to the choice of whether to ingest or reject a tastant. In rats, the decision to reject an aversive stimulus is clearly marked by the onset of gaping, which is an easily identified orofacial movement. By contrast, palatable tastants elicit a complex set of ingestive-related behaviors, complicating efforts to pinpoint the precise onset of ingestion and to investigate the neural processes preceding this decision. In Chapter 2, I present an analysis designed to disentangle the ingestive response: a classifier capable of identifying individual consummatory behaviors from electromyographic (EMG) activity in the jaw opener muscle. Further analyses reveal that ingestion decisions are reflected through an ensemble of interacting behaviors whose temporal patterns align with the onset of palatability-related activity in Gustatory Cortex. In Chapter 3, I examine CPG modulation in a complementary model system, the cardiac ganglion of the Jonah crab, and provide morphological evidence that the neuropil and the soma of motor neurons serve as key sites of neuromodulatory integration. In a final chapter, I conclude with a synthesis of these results and discuss future studies aimed at further characterizing the organization and function of ingestive-related behaviors uncovered in this thesis.