Altered connectivity among emotion-related brain regions during short-term memory in Alzheimer's disease

Rosenbaum, R. Shayna; Furey, Maura L.; Horwitz, Barry; Grady, Cheryl L.

doi:10.1016/j.neurobiolaging.2008.06.002

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Volume 31, Issue 5 , Pages 780-786, May 2010

Altered connectivity among emotion-related brain regions during short-term memory in Alzheimer's disease☆

R. Shayna Rosenbaum
- Department of Psychology, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3
- The Rotman Research Institute, Baycrest, 3560 Bathurst Street, Toronto, Ontario, Canada M5A 2E1
- Corresponding author at: Department of Psychology, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3. Tel.: +1 416 736 2100x20449; fax: +1 416 736 5662.
Maura L. Furey
- Neuroimaging Section, Mood and Anxiety Disorders Program, National Institute of Mental Health, National Institutes of Health, 15K North Drive, Bethesda, MD 20892, USA
Barry Horwitz
- Brain Imaging and Modeling Section, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, 10 Center Drive, Bethesda, MD 20892, USA
Cheryl L. Grady
- The Rotman Research Institute, Baycrest, 3560 Bathurst Street, Toronto, Ontario, Canada M5A 2E1
- Departments of Psychology and Psychiatry, University of Toronto, 100 St. George Street, Toronto, Ontario, Canada M5S 3G3

Received 5 October 2007; received in revised form 30 May 2008; accepted 9 June 2008. published online 21 July 2008.

Abstract

A PET study of patients with Alzheimer's disease (AD) engaged in a delayed match-to-sample face recognition task revealed that performance declines as a function of increasing delay, a pattern accompanied by reduced functional connectivity of prefrontal cortex but increased connectivity of the left amygdala. Here, we characterize the changes in interactions within this amygdalar circuit across the memory delays using structural equation modeling. The magnitude of effective connections was found to be much greater in the patients than in the controls, notably from the left amygdala to left inferior prefrontal cortex, which, in turn, influenced its right homologue. The influence from the amygdala to the left hippocampus, in contrast, was not strong in either group. We interpret this pattern of interactions as possibly reflecting the compensatory recruitment of a dynamic neural network, perhaps involved in implicit emotional processing, in the context of a faulty executive maintenance and retrieval system.

Keywords: Aging, Structural equation modeling, Amygdala, Hippocampus, Inferior prefrontal cortex, Plasticity