Brain Substrates of Time-Based Prospective Memory Decline in Aging: A Voxel-Based Morphometry and Diffusion Tensor Imaging Study
Résumé
Time-based prospective memory (TBPM) allows us to remember to perform intended actions
at a specific time in the future. TBPM is sensitive to the effects of age, but the neural substrates of this
decline are still poorly understood. The aim of the present study was thus to better characterize the
brain substrates of the age-related decline in TBPM, focusing on macrostructural gray-matter and
microstructural white-matter integrity. We administered a TBPM task to 22 healthy young (26 ± 5.2
years) and 23 older (63 ± 5.9 years) participants, who also underwent volumetric magnetic resonance
imaging and diffusion tensor imaging scans. Neuroimaging analyses revealed lower gray-matter
volumes in several brain areas in older participants, but these did not correlate with TBPM
performance. By contrast, an age-related decline in fractional anisotropy in several white-matter tracts
connecting frontal and occipital regions did correlate with TBPM performance, while there was no
significant correlation in healthy young subjects. According to the literature, these tracts are connected
to the anterior prefrontal cortex and the thalamus, two structures involved in TBPM. These results
confirm the view that a disconnection process occurs in aging and contributes to cognitive decline.
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