Evaluating Anesthetic Protocols for Non-Human Primate Functional Neuroimaging
Abstract
Functional magnetic resonance imaging (fMRI) is a non-invasive technique that can be used to measure a proxy of neural activity in vivo with high spatial specificity. One subject can be followed for a long period of time to assess changes in functional brain organization. However, fMRI is extremely sensitive to motion. The challenges of training non-human primates to reduce motion in an MRI scanner motivate the study of anesthesia which is commonly used to substitute for this training. In this thesis, I compare three different commonly used anesthetic protocols: isoflurane, propofol-fentanyl in combination, and fentanyl alone, to test which of these best preserves a Blood Oxygen Level Dependent (BOLD) response to visual and somatosensory sensory stimuli in two rhesus macaque (Macaca mulatta) monkeys. In one animal, somatosensory responses were equally robust under propofol-fentanyl and fentanyl anesthesia but in the other animal, these responses were only robust under propofol-fentanyl. Somatosensory and visual responses were not observed under isoflurane anesthesia for either animal. It was under fentanyl and combinations with fentanyl that both sensory modalities appeared to best-elicit sensory related BOLD signals in these animals suggesting they should be further studied in a larger cohort.