Increased prefrontal cortical activation during challenging walking conditions in persons with lower limb amputation – an fNIRS observational study

ABSTRACT

Background: Lower limb amputation (LLA) alters the sensorimotor control systems. Despite the self-reports of increased attention during mobility, the interaction between mobility and cognitive control mechanisms is not fully understood.

Objective: Concurrently evaluate walking performance and prefrontal cortical (PFC) activity in persons with and without LLA during different walking conditions.

Methods: Thirty-nine persons with LLA and thirty-three able-bodied controls participated. Walking performance was evaluated using the Figure-of 8-walk-test during three conditions: 1) UW (Usual walking with self-selected walking speed); 2) WCT (walking and carrying a tray with two cups filled with water); and 3) WUT (walking on uneven terrain). PFC activity was assessed using functional near-infrared spectroscopy (fNIRS). Linear mixed models were used to detect changes between groups and between walking conditions within each group.

Results: Between-group comparisons showed increased PFC activity in persons with LLA during UW and WUT, and a significant decrease in walking performance during WCT and WUT compared to controls. Within-group comparisons showed increased PFC activity during WUT compared with UW and WCT and an overall difference in walking performance between the conditions (WU > WUT > WCT) in both groups. However, the effect of walking condition on PFC activity and walking performance was not modified by group (P > .1).

Conclusion: The results suggest that persons with LLA have increased attentional demands during walking but choose the same cognitive-mobility strategy during challenging walking conditions as able-bodied persons. However, the attentional demands seem to depend on the complexity of the task.

KEYWORDS:

• Cognitive load
• attention
• artificial limb
• gait
• neuroimaging

Acknowledgments

This work was supported by the foundation “Stiftelsen Sophies Minde” Oslo, Norway (1203). ISPO (International Society for Prosthetics and Orthotics) Norway provided a grant for some of the data collection expenses. The authors would like to thank Lamija Pasalic, NIRX for her support with data analysis.

Disclosure Statement

The authors declare no conflicts of interest.

Additional information

Funding

This work was supported by the foundation “Stiftelsen Sophies Minde”. ISPO  Norway (International Society for Prosthetics and Orthotics), provided a grant for parts of the data collection expenses.