Journal
JOURNAL OF NEUROSCIENCE
Volume 26, Issue 40, Pages 10222-10231Publisher
SOC NEUROSCIENCE
DOI: 10.1523/JNEUROSCI.2250-06.2006
Keywords
Alzheimer's disease; mild cognitive impairment; fMRI; hippocampus; default mode network; independent component analyses
Categories
Funding
- NCRR NIH HHS [P41 RR014075, P41-RR14075] Funding Source: Medline
- NIA NIH HHS [P50-AG05134, P01 AG004953, P01-AG04953, P50 AG005134] Funding Source: Medline
- NINDS NIH HHS [K23 NS002189, K23-NS02189] Funding Source: Medline
Ask authors/readers for more resources
Memory function is likely subserved by multiple distributed neural networks, which are disrupted by the pathophysiological process of Alzheimer's disease ( AD). In this study, we used multivariate analytic techniques to investigate memory-related functional magnetic resonance imaging (fMRI) activity in 52 individuals across the continuum of normal aging, mild cognitive impairment (MCI), and mild AD. Independent component analyses revealed specific memory-related networks that activated or deactivated during an associative memory paradigm. Across all subjects, hippocampal activation and parietal deactivation demonstrated a strong reciprocal relationship. Furthermore, we found evidence of a nonlinear trajectory of fMRI activation across the continuum of impairment. Less impaired MCI subjects showed paradoxical hyperactivation in the hippocampus compared with controls, whereas more impaired MCI subjects demonstrated significant hypoactivation, similar to the levels observed in the mild AD subjects. We found a remarkably parallel curve in the pattern of memory-related deactivation in medial and lateral parietal regions with greater deactivation in less-impaired MCI and loss of deactivation in more impaired MCI and mild AD subjects. Interestingly, the failure of deactivation in these regions was also associated with increased positive activity in a neocortical attentional network in MCI and AD. Our findings suggest that loss of functional integrity of the hippocampal-based memory systems is directly related to alterations of neural activity in parietal regions seen over the course of MCI and AD. These data may also provide functional evidence of the interaction between neocortical and medial temporal lobe pathology in early AD.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available