Age-related functional connectivity along the hippocampal longitudinal axis

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neuroimaging

Background:

• Evidence suggests a functional division of the hippocampus along its longitudinal axis.
• Anterior hippocampus is linked to emotion, posterior to navigation and cognition.
• Limited understanding exists on how age impacts hippocampal functional connectivity.

Purpose of the Study:

• To investigate age-related differences in functional connectivity along the hippocampal longitudinal axis.
• To map distinct functional connections of anterior, middle, and posterior hippocampus with other brain regions.
• To understand how aging affects these specific hippocampal network connections.

Main Methods:

• Utilized a large resting-state functional magnetic resonance imaging (fMRI) dataset.
• Applied an anatomically driven general linear model (GLM) for functional connectivity analysis.
• Examined functional connectivity patterns across different hippocampal sub-regions and their relationship with age.

Main Results:

• Posterior hippocampus shows connectivity with sensory/motor areas; middle with default mode network; anterior with limbic/prefrontal regions, irrespective of age.
• Aging correlates with decreased functional connectivity in middle and posterior hippocampus with cortical regions.
• Anterior hippocampus and ventral striatum show increased synchronization with age, alongside reduced intra-hippocampal uniformity.

Conclusions:

• Hippocampal sub-regions are specialized for distinct functional networks.
• These specialized networks exhibit differential aging patterns.
• Hippocampal aging is not uniform across its longitudinal axis.