Abstract
Aging is associated with structural and functional changes in the hippocampus, and hippocampal dysfunction represents a risk marker of Alzheimer’s disease. Previously, we demonstrated age-related changes in reactive and proactive control in the stop signal task, each quantified by the stop signal reaction time (SSRT) and sequential effect computed as the correlation between the estimated stop signal probability and go trial reaction time. Age was positively correlated with the SSRT, but not with the sequential effect. Here, we explored hippocampal gray matter volume (GMV) and activation to response inhibition and to p(Stop) in healthy adults 18 to 72 years of age. The results showed age-related reduction of right anterior hippocampal activation during stop success vs. go trials, and the hippocampal activities correlated negatively with the SSRT. In contrast, the right posterior hippocampus showed higher age-related responses to p(Stop), but the activities did not correlate with the sequential effect. Further, we observed diminished GMVs of the anterior and posterior hippocampus. However, the GMVs were not related to behavioral performance or regional activities. Together, these findings suggest that hippocampal GMVs and regional activities represent distinct neural markers of cognitive aging, and distinguish the roles of the anterior and posterior hippocampus in age-related changes in cognitive control.
Highlights
Memory impairment is the most important characteristic of age-related cognitive deficits, as observed in individuals with mild cognitive impairment (MCI) and Alzheimer’s Disease (AD).The processing of contextual information depends critically on the hippocampus [1,2]
Whereas the gray matter volume (GMV) of the anterior and posterior hippocampus decreased with age, the GMVs were not correlated with stop signal reaction time (SSRT) or with the sequential effect
The activation of the right anterior hippocampus during reactive inhibitory control was negatively associated with age, and the activation of the right posterior hippocampus in proactive control was positively associated with age
Summary
Memory impairment is the most important characteristic of age-related cognitive deficits, as observed in individuals with mild cognitive impairment (MCI) and Alzheimer’s Disease (AD). The processing of contextual information depends critically on the hippocampus [1,2]. Hippocampal atrophy represents a biomarker of MCI and early-stage AD [3,4]. Along with impairment in spatial [5] and verbal memory [6] task performance, hippocampal atrophy is associated with higher risk of developing AD. Hippocampal structural and functional changes may predict cognitive decline [10,11]. Hippocampal dysfunction represents a critical etiological marker of age-related cognitive decline and AD
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