Interaction Between Age and Task Demand on Brain Connectivity Associated With Mastication

Sensorimotor processing is critical to the ageing brain and geriatric health. Masticatory performance (MP) is key to the systemic health of older individuals. Neuroimaging research has revealed a potential link between brain functional connectivity (FC) and MP. Using the masticatory perturbation task (MPT), we investigated the FC associated with MP under different conditions of task demand and age groups.

Thirty-four older-age (OA, ≥ 65 years), 26 middle-aged (MA, between 40 and 64 years) and 42 younger-age (YA, < 40 years) participants were recruited for assessment of the MPT, and structural and resting-state (rs) functional magnetic resonance imaging (MRI). Analyses of seed-based connectivity and FC networks were conducted to investigate the rs-FC associated with MP in the baseline condition (without perturbation) and the perturbation condition (with perturbation) of MPT.

(A) In the baseline condition, OA participants with better MP showed higher rs-FC between the cerebellum and primary sensorimotor cortices. (B) In the perturbation condition, OA participants with better MP showed higher rs-FC between the middle frontal gyrus and the primary somatosensory cortex, and MA participants with better MP showed higher rs-FC between the supplementary motor area and the caudate nucleus. (C) The network analysis revealed that the pattern of rs-FC related to MP differed between age groups and task conditions. In the perturbation condition, YA participants with better MP showed higher rs-FC outside the sensorimotor network.

The findings provide novel evidence demonstrating an interaction between age and task demand on rs-FC associated with MP.