The role of the pre-frontal cortex in step initiation and aging related changes

Fast voluntary stepping is crucial to reducing fall risk in older adults. Older and younger adults (n = 20, mage = 69.4 years; n =21, mage = 26.9 years respectively) performed stepping tasks on force plates while functional Near Infrared Spectroscopy recorded neural activity in the Pre-Frontal Cortex (PFC). It was hypothesised that the PFC plays a role in step initiation and therefore would have greater activity for a choice step compared to a simple step, and this was supported (p = .041, ˜í‚àëp¬¨‚⧠= .11). Age differences in stepping under levels of cognitive load (forwards and backwards digit recall dual tasks) and step complexity (simple and choice stepping) were also investigated. Older adults' step initiation was significantly more slowed by the increased step complexity (p = .022, r = .44). For the backwards digit recall dual task, older adults employed a slower stepping strategy for both step types (p = .007, r = .43). Conversely, young adults maintained fast step initiation for both step types and upregulated PFC activity more for the choice step (p = .003, r = .47). Together these findings suggest that older adults could maintain comparable stepping and PFC involvement up until executive functions were strained through either increased step decision making or higher cognitive load. Future research aiming to improve older adults' stepping speed to reduce fall risk should target more complex stepping conditions.