Rhythmic oscillations in the brain are widespread. Extracellular recordings of local field potentials (LFPs) using methods ranging from microelectrodes to scalp electroencephalography (EEG) have demonstrated that oscillatory dynamics play a vital role in operations such as network synchronization, sensory tuning and information packaging. Empirical and computational evidence suggest that these oscillations carry meaningful information for sensory, cognitive and memory processes. Within the olfactory system, work in both vertebrates and invertebrates has established that odor-induced oscillatory activity is a distinctive neural signature. This activity is found in the olfactory bulb, piriform cortex (PC), and amygdala and entorhinal cortex, which is described by slow oscillations in phase with respiration, and faster oscillations in the beta and gamma frequency ranges. Whether the human olfactory brain engages the same electrophysiological mechanisms as identified in animal models remains poorly understood. In this dissertation I present a pair of experiments using intracranial EEG to elucidate the electrophysiological properties of human olfactory cortex. The first study explored the foundation of human olfactory oscillations during a cued odor detection task. We evaluated the spatial and spectro-temporal dynamics of initial odor processing and found that low frequency theta activity was prominent during odor sampling, could decode odor identity with high accuracy, and that piriform and hippocampus were phase locked during odor sampling in the theta range. This study established theta as an organizing principle around which odor processing occurs within olfactory cortex. In the second study, we again applied intracranial EEG to study olfactory cortex oscillations in the context of an olfactory working memory paradigm, focusing on the extent to which human olfactory cortex employs temporal phase coding models to encode odor object and sequence information. We replicated the findings from the first study showing elevated theta activity during olfactory processing relative to non-olfactory processing and demonstrated the phase and amplitude frequencies that govern cross-frequency coupling within olfactory cortex during odor sampling. Finally, we showed that specific patterns of phase amplitude coupling – or phase coding – can decode odor identity within piriform cortex, suggesting that categorical information is encoded via cross frequency coupling. Together these studies demonstrate how the electrophysiological mechanisms of information processing and transmission operate within human piriform cortex to guide perception and action.

Creator

• JIang, Han

DOI

• https://doi.org/10.21985/n2-55b4-m198

Subject

• Neurosciences

Language

• en

Alternate Identifier

• etdadmin_upload_641773
• http://dissertations.umi.com/northwestern:14545

Date created

• 2019-01-01

Resource type

• Dissertation

Rights statement

• In Copyright