Cortical activity during supported and unsupported choice-stepping reaction time tasks in young and older people: a functional near-infrared spectroscopy study.

Both young and older participants had slower stepping response times in the unsupported condition compared to the supported condition across all three stepping tasks.

• Thirty-two young and 48 older people participated in the study.
• Three stepping tasks were tested: choice stepping reaction time (CSRT), inhibitory CSRT (iCSRT), and stroop stepping (SST).
• The effect was statistically significant (p < 0.05) across both age groups and all three tasks.
• Tasks were performed on a computerised step mat in two randomly presented support conditions: supported standing using armrests and unsupported free standing.

Increased cortical activation in the PFC, SMA, and PMC was observed in the unsupported versus supported condition for the CSRT task in the young cohort only.

• The effect was statistically significant (p < 0.05) in young participants.
• Cortical activity was measured using functional near-infrared spectroscopy (fNIRS).
• The three cortical regions measured were the dorsolateral prefrontal cortex (DLPFC), supplementary motor area (SMA), and premotor cortex (PMC).
• Older participants did not show the same pattern of increased cortical activation between support conditions.
• The authors interpreted this as supporting the involvement of these cortical regions in balance control.

Cortical activity levels were similar between the supported and unsupported conditions for both groups in the more cognitively demanding iCSRT and SST tasks.

• This pattern was observed in both young and older participants.
• The authors proposed two possible explanations: the cognitive component of these tasks may have overshaded the motor component, and/or these tasks may have promoted automaticity of postural control by distracting participants from focusing on maintaining balance.
• The iCSRT and SST tasks were described as 'more cognitively demanding' than the standard CSRT task.
• No significant differences in cortical activity between support conditions were found for these tasks.

The study investigated cortical activity during stepping tasks in both young and older healthy people to examine the role of balance control in cortical resource allocation.

• The study included 32 young and 48 older participants.
• The research question addressed whether cortical activity during balance relates disproportionally to balance control or simply to the undertaking of any motor task.
• Potential effects of aging on this relationship were also examined.
• fNIRS was used to measure mean stepping response times, step errors, and cortical activity simultaneously.

Older participants did not show differential cortical activation between supported and unsupported conditions even in the basic CSRT task, unlike young participants.

• Young participants showed increased cortical activation (DLPFC, SMA, PMC) in unsupported versus supported CSRT (p < 0.05), while older participants did not.
• This age-related difference in cortical response to balance demands was a key finding of the study.
• The aging effect on the cortical activity-balance control relationship was described as 'unknown' prior to this study.
• Both groups had 48 older and 32 young participants respectively, providing sufficient sample sizes to compare age groups.