Cortical representation of motion sequence processing in younger and older adults: an fMRI study

Processing motion sequences is essential for daily activities such as driving. While aging affects various cognitive and neural functions, how older adults process motion sequences in the brain remains poorly understood. This study investigated age-related differences in the neural processing of motion sequences between younger and older adults using functional magnetic resonance imaging (fMRI). Twenty-four younger and 27 older adults viewed static picture quartets depicting dynamic sports actions and rated the coherence of each sequence on a four-point Likert scale. Stimuli comprised real-life action sequences in three conditions: ordered, randomized, and grid-scrambled. Results demonstrated that while younger adults' ratings consistently tracked stimulus order, older adults showed reduced sensitivity to ordered sequences compared to younger adults, though their ratings remained higher for ordered than randomized sequences. Notably, older adults exhibited enhanced left-lateralized frontal responses, and several clusters showing age differences overlapped with regions commonly associated with the default mode network, including the medial frontal and angular gyri, during randomized sequence processing compared to younger adults. These findings reveal age-related differences in the cortical mechanisms underlying motion sequence processing, with older adults engaging more top-down cortical resources when processing randomized motion sequences. This research provides new insights into how aging shapes the cortical representation of motion sequence information in the brain.