Activation and Effective Connectivity Changes Following Explicit-Memory Training for Face–Name Pairs in Patients With Mild Cognitive Impairment: A Pilot Study

• Type of Material: Article
• Authors: Benjamin Hampstead, Emory University; Anthony Stringer, Emory University; Randall F. Stilla, Emory University; Gopikrishna Deshpande, Emory University; Xiaoping P Hu, Emory University; Anna Bacon Moore, Emory University; Krish Sathian, Emory University
• Language: English
• Date: 2011
• Publisher: SAGE Publications (UK and US)
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © The Author(s) 2011
• Final Published Version (URL): http://nnr.sagepub.com/content/25/3/210
• Title of Journal or Parent Work: Neurorehabilitation & Neural Repair
• ISSN: 1545-9683
• Volume: 25
• Issue: 3
• Start Page: 210
• End Page: 222
• Grant/Funding Information: This material is based upon work supported by the Department of Veterans Affairs, Veterans Health Administration, Office of Research and Development, and Rehabilitation Research and Development Service through grants B4602H & B6366W to B.H., B3323K and B4954N to A.M.; Support to KS from the Atlanta VAMC and from National Institutes of Health (NIH) grant K24 EY017332 and to XH from Georgia Research Alliance and NIH grant R01EB002009 is also gratefully acknowledged.; This work was also funded by the Atlanta VAMC RR&D Center of Excellence.
• Keywords: cognitive rehabilitation; mnemonic strategy; Alzheimer’s disease; functional magnetic resonance imaging (fMRI); aging; Granger causality analysis
• Research Categories: Biology, Neuroscience; Health Sciences, Rehabilitation and Therapy

Abstract

Background: Mild cognitive impairment (MCI) is often a precursor to Alzheimer’s disease. Little research has examined the efficacy of cognitive rehabilitation in patients with MCI, and the relevant neural mechanisms have not been explored. We previously reported on a pilot study showing the behavioral efficacy of cognitive rehabilitation using mnemonic strategies for face-name associations in patients with MCI. Here we used functional magnetic resonance imaging (fMRI) to test whether there were training-specific changes in activation and connectivity within memory-related areas. Methods: Six patients with amnestic, multi-domain MCI underwent pre- and post-training fMRI scans, during which they encoded 90 novel face-name pairs, and completed a 4-choice recognition memory test immediately after scanning. Patients were taught mnemonic strategies for half the face-name pairs during three intervening training sessions. Results: Training-specific effects comprised significantly increased activation within a widespread cerebral cortical network involving medial frontal, parietal, and occipital regions, the left frontal operculum and angular gyrus, and regions in left lateral temporal cortex. Increased activation common to trained and untrained stimuli was found in a separate network involving inferior frontal, lateral parietal and occipital cortical regions. Effective connectivity analysis using multivariate, correlation-purged Granger causality analysis revealed generally increased connectivity after training, particularly involving the middle temporal gyrus and foci in the occipital cortex and the precuneus. Conclusion: Our findings suggest that the effectiveness of explicit memory training in patients with MCI is associated with training-specific increases in activation and connectivity in a distributed neural system that includes areas involved in explicit memory.