Neuropsychological and functional neuroimaging studies have suggested that specific regions of frontal and medial temporal cortex are engaged during episodic memory formation. Further, there is specialization across these regions such that verbal materials appear to preferentially engage left regions while nonverbal materials primarily engage right regions. These hemispheric differences likely reflect lateralization of the verbal and nonverbal processing mechanisms used to memorize different kinds of information. An open question, however, has been how each of these regions specifically contributes to the formation of a memory. The overall goal of the proposed research is to characterize the involvement of specific brain regions in episodic memory formation using functional magnetic resonance imaging (fMRI). Specifically, experiments are proposed to better understand the contributions of dorsal frontal cortex and the hippocampal formation to aspects of episodic encoding. Experiments are proposed to: (1) better characterize the contributions of left and right dorsal frontal cortex during memory encoding, and (2) better understand the functional role of the hippocampal formation during memory encoding. For example, does left dorsal frontal activity reflect access to phonological information (i.e. a verbal label) or more general semantic information? Is the right-sided `nonverbal' activity specific to visually-presented materials, or can it be evoked for materials presented in other sensory modalities (e.g. sounds)? Is hippocampal activity more sensitive to the novelty of individual items or the relationship between items? A series of fMRI studies will address these issues. Taken together, these studies will provide important insights into the specific cognitive operations engaged by frontal and medial temporal brain regions during memory formation. Such insight may ultimately aid in the development of more effective cognitive rehabilitation strategies for the treatment of brain injury.
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