Online fronto-cortical control of simple and attention-demanding locomotion in humans

Abstract

Knowledge of online functional brain mechanisms of locomotion is scarce due to technical limitations of traditional neuroimaging methods. Using functional Near Infrared Spectroscopy (fNIRS) we evaluated task-related changes in oxygenated hemoglobin levels (HbO2) in real-time over the pre-frontal-cortex (PFC) regions during simple (Normal Walk; NW) and attention-demanding (Walking While Talking; WWT) locomotion tasks in a large cohort of non-demented older adults. Results revealed that the assessment of task-related changes in HbO2 was internally consistent. Imposing greater demands on the attention system during locomotion resulted in robust bilateral PFC increases in HbO2 levels during WWT compared to NW and the cognitive interference tasks. Elevated PFC oxygenation levels were maintained throughout the course of WWT but not during the NW condition. Increased oxygenation levels in the PFC were related to greater stride length and better cognitive performance but not to faster gait velocity in WWT. These findings elucidate online brain mechanisms of locomotion, and confer significant implications for risk assessment and intervention for major mobility outcomes.

Copyright © 2015 Elsevier Inc. All rights reserved.

Figures

Figure 1

Apparatus and synchronized communication center: fNIRS device and sensor, PKMAS device and instrumented walkway, and E-prime computer. fNIRS=functional Near Infrared Spectroscopy; PKMAS= ProtoKinetics Movement Analysis Software

Figure 2

Mean HbO2 levels in NW and WWT are depicted as a function of six consecutive straight walks that were extracted from each walking condition. There is no parallel time course for Alpha. Overall mean HbO2 level in Alpha (.68±.54) is provided herein as a reference. NW=Normal Walk; WWT=Walk While Talk