Jed Meltzer
Graduate Student
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I am a third year neuroscience graduate student in Todd Constables lab. I am interested in the potential of fMRI to reveal characteristics of neural information processing that do not fit the standard "lighting up" model. Perception and processing of sensory stimuli typically cause detectable increases in the amount of synaptic input to a given area. However, the BOLD signal represents only a small incremental change in the energy use of that area. It is likely that many forms of specific information processing related to memory and active manipulation of stored representations may result in no detectable change in the BOLD signal, or even a decrease. For example, implicit recognition of visual stimuli, as indexed by priming, often results in a decrease in the magnitude of the hemodynamic response to said stimuli in higher-order association cortices.
My dissertation project is an investigation of the link
between systematic fMRI deactivations (brain areas that exhibit decreases in
BOLD signal in a wide variety of cognitive tasks) and electrophysiological
measures of neuronal osciillatory synchrony. It is likely that a state of
synchronous oscillation, such as hippocampal theta rhythm, may play an
important role in information processing, despite being metabolically
depressed relative to a baseline state. To investigate the role of synchronous
oscillations in humans, I am using combined EEG/FMRI recording, as well as
intracranial recording in epilepsy patients undergoing presurgical evaluation,
in collaboration with Dr. Dennis Spencer. More broadly, I am interested in the
role of cortico-hippocampal interaction in declarative memory and language
processing. Additionally, I have a strong side interest in the use of
computational models to predict the observable hemodynamic and
electrophysiological responses of theoretical neuronal network architectures.
