Perceptual Binding and Episodic Memory

Stanford University, Stanford CA

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Abstract

[unreadable] DESCRIPTION (provided by applicant): The broad aim of the proposed research program is to investigate the relationship between neurocognitive mechanisms giving rise to a multidimensional perceptual experience, and those that encode the experience in long-term memory. A novel paradigm will be employed to examine how the constituent elements of an experience-processed by distinct neural mechanisms-converge to form a coherent percept, and are subsequently encoded as an enduring 'episodic' memory. While much evidence supports the dual ideas that the creation of a unified percept ('perceptual binding') relies on attentional mechanisms in posterior parietal cortex (PPC), and that the formation of an integrated episodic memory relies on medial temporal lobe (MTL) encoding mechanisms, little is known about functional interactions between these mechanisms. By one account, MIL acts indiscriminately on the information projected to it, as mediated by attentional mechanisms. To the extent that this accurately describes the interplay between such mechanisms, the question arises whether the extent to which the multiple elements of an episode are perceived coherently changes the nature of the input to the MTL, and thus the resultant episodic representation. The proposed research aims to programmatically address this question by employing a novel paradigm that allows the factors of attention, perceptual and episodic binding to be independently assessed and correlated with functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) measures of neural activity. Expt 1 will employ fMRI to directly investigate the extent to which episodic binding is contingent on attentionally-mediated perceptual binding. Expt 2 will examine, with conventional fMRI and effective connectivity analyses, how attention to the various elements of an episode determines which MTL encoding mechanisms are engaged, and thus the type of memory formed. Finally, Expt 3 will characterize the temporal dimension of these operations by examining cross-regional synchronous oscillations in EEG signal. Delineating the manner in which the nature of the attention brought to bear on an experience influences the nature of encoding mechanisms promises to advance mechanistic accounts of encoding. PUBLIC HEALTH RELEVANCE: The proposed research will use fMRI and EEG to examine functional interactions between mechanisms of attention, perceptual binding, and episodic encoding. Characterizing the role of attentionally-mediated perceptual binding in the formation of informationally-rich memories will be directly relevant to understanding mechanisms of prevalent neurological conditions involving impairments in these processes, such as schizophrenia, Alzheimer's disease, depression, and attention deficit disorder. [unreadable] [unreadable] [unreadable]