P1‐262: Memory formation in middle‐aged adults: Dynamics of the bold signal across repetitions
| Autor: | Donald G. McLaren, Sterling C. Johnson, Michele E. Fitzgerald, Guofan Xu, Barbara B. Bendlin, Michele L. Ries, Erik K. Kastman, Lisa M. Newman, Kristopher J. Kosmatka, Britta M. Jabbar |
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| Rok vydání: | 2008 |
| Předmět: |
Neural correlates of consciousness
Communication Fusiform gyrus Epidemiology business.industry Health Policy Hippocampus Cognition Amygdala Visual processing Psychiatry and Mental health Cellular and Molecular Neuroscience medicine.anatomical_structure Developmental Neuroscience Encoding (memory) medicine Neurology (clinical) Geriatrics and Gerontology business Psychology Neuroscience Parahippocampal gyrus |
| Zdroj: | Alzheimer's & Dementia. 4 |
| ISSN: | 1552-5279 1552-5260 |
| Popis: | Background: Memory formation and retrieval is a dynamic process that employs a network of brain regions. Here we aim to investigate the neural correlates of memory formation in healthy middle-aged individuals using an event-related fMRI paradigm. Methods: Participants were asked to remember forty simple line drawings of objects that were presented and repeated three times in a pseudo-random order while collecting fMRI data. Two conceptual approaches were used to analyze the fMRI images. First, we used a traditional approach with parametric modulation based on repetition to investigate which regions showed attenuation in the BOLD response over repetitions. In the second approach, we examined how the hippocampus interacts with other brain regions across repetitions. Using an in-house variant of psychophysiological interactions (PPI) to investigate context-dependent connectivity, we were able to identify regions where connectivity with the left and right hippocampus did not change over repetition (repetition-invariant connectivity [RI]) and regions that changed with repetition (repetitiondependent connectivity [RD]). Results: The first approach revealed numerous regions exhibiting an adaptation response including the fusiform gyrus, parahippocampal gyrus, hippocampus, amygdala, ventral occipital lobes, and lateral frontal lobes. The second approach provides a dynamic picture of memory representation in the network over time. Early memory representation, at least for visual stimuli, appears dependent upon synchronous activation of the hippocampus, occipital lobes, and frontal regions; whereas representation during later encoding requires less connectivity between hippocampus and visual processing areas [RD], but continues to evoke similar connectivity with frontal regions [RI]. Conclusions: Importantly, these findings demonstrate a need to consider the effects of repetition on the BOLD signal in any memory paradigm. In addition to informing our understanding of normal memory function in terms of functional brain networks, we believe these methods will be critical to investigating memory change in aging and disease. Specifically, our in-house variant of PPI allows investigators to identify which connections, involved in a cognitive process, might be altered between groups. In the future, we aim at investigating the impact of risk-factors for Alzheimer’s disease on the alteration of these memory systems. |
| Databáze: | OpenAIRE |
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