Hippocampal activation and connectivity in the aging brain

Area of Science:

• Neuroscience
• Cognitive Aging
• Neuroimaging

Background:

• The hippocampus and surrounding cortices are vulnerable to age-related changes.
• Understanding these changes is vital for cognitive health in aging populations.

Purpose of the Study:

• To investigate brain activation and functional connectivity in cognitively normal older adults during a face-scene memory encoding task.
• To explore how hippocampal connectivity varies along its longitudinal axis during memory encoding.

Main Methods:

• Functional MRI (fMRI) scans were acquired from 210 older adults (mean age 76.4 years) during an associative face-scene encoding task.
• Activation patterns were analyzed, and functional connectivity of the hippocampus (head, body, tail) was examined during encoding.

Main Results:

• The face-scene task activated the hippocampus, ventral temporal cortices, and other brain regions including frontal, parietal, and occipital lobes.
• Hippocampal connectivity varied along its axis: head with frontal/temporal, body with widespread regions, and tail with posterior temporal/occipital cortices.
• Connectivity patterns for subsequently remembered items differed for hippocampal head and tail regions.

Conclusions:

• The face-scene task effectively engages the occipitotemporal visual pathway and medial temporal lobe.
• Hippocampal functional connectivity exhibits anterior-posterior specificity during memory encoding.
• These findings provide insights into brain-behavior relationships in aging and early Alzheimer's disease.