Abstract Cognitive reserve (CR) is the brain's capacity to cope with cerebral damage to minimize clinical manifestations. The ‘passive model’ considers head or brain measures as anatomical substrates ...of CR, whereas the ‘active model’ emphasizes the use of brain networks effectively. Sixteen healthy subjects, 12 amnestic mild cognitive impairment (MCI) and 16 cases with mild Alzheimer's disease (AD) were included to investigate the relationships between proxies of CR and cerebral measures considered in the ‘passive’ and ‘active’ models. CR proxies were inferred premorbid IQ (WAIS Vocabulary test), ‘education–occupation’, a questionnaire of intellectual and social activities and a composite CR measure. MRI-derived whole-brain volumes and brain activity by functional MRI during a visual encoding task were obtained. Among healthy elders, higher CR was related to larger brains and reduced activity during cognitive processing, suggesting more effective use of cerebral networks. In contrast, higher CR was associated with reduced brain volumes in MCI and AD and increased brain function in the latter, indicating more advanced neuropathology but that active compensatory mechanisms are still at work in higher CR patients. The right superior temporal gyrus (BA 22) and the left superior parietal lobe (BA 7) showed greatest significant differences in direction of slope with CR and activation between controls and AD cases. Finally, a regression analysis revealed that fMRI patterns were more closely related to CR proxies than brain volumes. Overall, inverse relationships for healthy and pathological aging groups emerged between brain structure and function and CR variables.
In the present study, we aimed to investigate the effects of repetitive transcranial magnetic stimulation (rTMS) on memory performance and brain activity in elders presenting with subjective memory ...complaints and a memory performance within the low normal range. Forty participants underwent 2 functional magnetic resonance imaging (fMRI) sessions, in which they were administered 2 equivalent face–name memory tasks. Following each fMRI, subjects were asked to pair faces with their corresponding proper name. In-between, high-frequency rTMS was applied randomly using real or sham stimulation in a double-blind design. Only subjects who received active rTMS improved in associative memory significantly. This was accompanied by additional recruitment of right prefrontal and bilaterial posterior cortical regions at the second fMRI session, relative to baseline scanning. Our findings reflect a potentiality of rTMS to recruit compensatory networks, which participate during the memory-encoding process. Present results represent the first evidence that rTMS is capable of transitorily and positively influencing brain function and cognition among elders with memory complaints.
Abstract The purpose of the present study was to evaluate functional connectivity of the hippocampus during a fMRI face–name learning task in a group of elders with mild memory impairment on the ...basis of the presence or absence of the APOE ε4 allele. Twelve ε4 carriers and 20 non-carriers with mild memory dysfunction and exhibiting equivalent performance in clinical evaluations of global cognitive function and memory were studied. Subjects underwent a fMRI session consisting of a face–name encoding memory task. Following scanning, subjects were asked to pair faces with their corresponding proper name. Functional connectivity of the hippocampus was measured by using coherence analysis to evaluate the activity of brain circuits related to memory encoding processes. In contrast to non- APOE ε4 allele bearers, APOE ε4 carriers showed enhanced connectivity with the anterior cingulate, inferior parietal/postcentral gyrus region and the caudate nucleus. Enhanced hippocampal connectivity with additional brain regions in APOE ε4 allele carriers during the performance of an associative memory task may reveal the existence of additional activity in the cortico-subcortical network engaged during memory encoding in subjects carrying this genetic variant.
The purpose of the present study was to evaluate functional connectivity of the hippocampus during a fMRI face-name learning task in a group of elders with mild memory impairment on the basis of the ...presence or absence of the APOE var epsilon4 allele. Twelve var epsilon4 carriers and 20 non- carriers with mild memory dysfunction and exhibiting equivalent performance in clinical evaluations of global cognitive function and memory were studied. Subjects underwent a fMRI session consisting of a face-name encoding memory task. Following scanning, subjects were asked to pair faces with their corresponding proper name. Functional connectivity of the hippocampus was measured by using coherence analysis to evaluate the activity of brain circuits related to memory encoding processes. In contrast to non-APOE var epsilon4 allele bearers, APOE var epsilon4 carriers showed enhanced connectivity with the anterior cingulate, inferior parietal/postcentral gyrus region and the caudate nucleus. Enhanced hippocampal connectivity with additional brain regions in APOE var epsilon4 allele carriers during the performance of an associative memory task may reveal the existence of additional activity in the cortico- subcortical network engaged during memory encoding in subjects carrying this genetic variant.
The purpose of the present study was to evaluate functional connectivity of the hippocampus during a fMRI face–name learning task in a group of elders with mild memory impairment on the basis of the ...presence or absence of the
APOE ɛ4 allele. Twelve ɛ4 carriers and 20 non-carriers with mild memory dysfunction and exhibiting equivalent performance in clinical evaluations of global cognitive function and memory were studied. Subjects underwent a fMRI session consisting of a face–name encoding memory task. Following scanning, subjects were asked to pair faces with their corresponding proper name. Functional connectivity of the hippocampus was measured by using coherence analysis to evaluate the activity of brain circuits related to memory encoding processes. In contrast to non-
APOE ɛ4 allele bearers,
APOE ɛ4 carriers showed enhanced connectivity with the anterior cingulate, inferior parietal/postcentral gyrus region and the caudate nucleus. Enhanced hippocampal connectivity with additional brain regions in
APOE ɛ4 allele carriers during the performance of an associative memory task may reveal the existence of additional activity in the cortico-subcortical network engaged during memory encoding in subjects carrying this genetic variant.
The purpose of the present study was to evaluate functional connectivity of the hippocampus during a fMRI face-name learning task in a group of elders with mild memory impairment on the basis of the ...presence or absence of the APOE epsilon4 allele. Twelve epsilon4 carriers and 20 non-carriers with mild memory dysfunction and exhibiting equivalent performance in clinical evaluations of global cognitive function and memory were studied. Subjects underwent a fMRI session consisting of a face-name encoding memory task. Following scanning, subjects were asked to pair faces with their corresponding proper name. Functional connectivity of the hippocampus was measured by using coherence analysis to evaluate the activity of brain circuits related to memory encoding processes. In contrast to non-APOE epsilon4 allele bearers, APOE epsilon4 carriers showed enhanced connectivity with the anterior cingulate, inferior parietal/postcentral gyrus region and the caudate nucleus. Enhanced hippocampal connectivity with additional brain regions in APOE epsilon4 allele carriers during the performance of an associative memory task may reveal the existence of additional activity in the cortico-subcortical network engaged during memory encoding in subjects carrying this genetic variant.
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