Modifications in Prefrontal Cortex Oxygenation in Linear and Curvilinear Dual Task Walking: A Combined fNIRS and IMUs Study

Abstract

Increased oxygenated hemoglobin concentration of the prefrontal cortex (PFC) has been observed during linear walking, particularly when there is a high attention demand on the task, like in dual-task (DT) paradigms. Despite the knowledge that cognitive and motor demands depend on the complexity of the motor task, most studies have only focused on usual walking, while little is known for more challenging tasks, such as curved paths. To explore the relationship between cortical activation and gait biomechanics, 20 healthy young adults were asked to perform linear and curvilinear walking trajectories in single-task and DT conditions. PFC activation was assessed using functional near-infrared spectroscopy, while gait quality with four inertial measurement units. The Figure-of-8-Walk-Test was adopted as the curvilinear trajectory, with the "Serial 7s" test as concurrent cognitive task. Results show that walking along curvilinear trajectories in DT led to increased PFC activation and decreased motor performance. Under DT walking, the neural correlates of executive function and gait control tend to be modified in response to the cognitive resources imposed by the motor task. Being more representative of real-life situations, this approach to curved walking has the potential to reveal crucial information and to improve people' s balance, safety, and life's quality.

Keywords: acceleration; biomechanics; cortical activity; curved walking; functional near-infrared spectroscopy; gait performance; gait quality; inertial sensors; locomotion; wearable technology.

Figure 1

Whiskers’ plots: Enumerated numbers during the 30s of each task are reported; percentage at the top describes the accuracy of the given answers. DT = dual task; F8WT = Figure-of-8 Walk test.

Figure 2

Median and interquartile ΔO₂Hb values are reported. Horizontal lines and asterisks indicate significant statistical differences. ST = single task; DT = dual task; F8WT = Figure-of-8 Walk test * = p < 0.05.

Figure 3

Median and interquartile values are displayed. Horizontal lines and asterisks indicate significant statistical differences. F8WT = Figure-of-8 Walk test; ST = single task; DT = dual task; nRMS = normalized root mean square; ACPS = attenuation coefficient pelvis-sternum; AP = antero-posterior; ML = medio-lateral; CC = cranio-caudal.; * p < 0.05.

Figure 4

O₂Hb = oxygenated hemoglobin; SF = stride frequency; SD = stride duration; F8WT = Figure-of-8 Walk test; ST = single task; DT = dual task; P = pelvis; T = trunk; S-T = spatio-temporals; nRMS = normalized root mean square; ACPS = attenuation coefficient pelvis-sternum; AP = antero-posterior; ML = medio-lateral; * = p < 0.05; ** = p < 0.01.