Abstract
Background: Functional near-infrared spectroscopy (fNIRS) is a valuable neuroimaging approach for studying cortical contributions to walking function. Recruitment of prefrontal cortex during walking has been a particular area of focus in the literature. The present study investigated whether task-related change in prefrontal recruitment measured by fNIRS is affected by individual differences in people post-stroke. The primary hypotheses were that poor mobility function would contribute to prefrontal over-recruitment during typical walking, and that poor cognitive function would contribute to a ceiling in prefrontal recruitment during dual-task walking (i.e., walking with a cognitive task).Methods: Thirty-three adults with chronic post-stroke hemiparesis performed three tasks: typical walking at preferred speed (Walk), serial-7 subtraction (Serial7), and walking combined with serial-7 subtraction (Dual-Task). Prefrontal recruitment was measured with fNIRS and quantified as the change in oxygenated hemoglobin concentration (ΔO2Hb) between resting and active periods for each task. Spatiotemporal gait parameters were measured on an electronic walkway. Stepwise regression was used to assess how prefrontal recruitment was affected by individual differences including age, sex, stroke region, injured hemisphere, stroke chronicity, 10-meter walking speed, balance confidence measured by Activities-specific Balance Confidence (ABC) Scale, sensorimotor impairment measured by Fugl-Meyer Assessment, and cognitive function measured by Mini-Mental State Examination (MMSE).Results: For Walk, poor balance confidence (ABC Scale score) significantly predicted greater prefrontal recruitment (ΔO2Hb; R2 = 0.25, p = 0.003). For Dual-Task, poor cognitive function (MMSE score) significantly predicted lower prefrontal recruitment (ΔO2Hb; R2 = 0.25, p = 0.002).Conclusions: Poor mobility function predicted higher prefrontal recruitment during typical walking, consistent with compensatory over-recruitment. Poor cognitive function predicted lower prefrontal recruitment during dual-task walking, consistent with a recruitment ceiling effect. These findings indicate that interpretation of prefrontal recruitment should carefully consider the characteristics of the person and demands of the task.
Highlights
Stroke side and lesion location for each participant was determined from medical records, and the location was broadly categorized as: anterior cerebral artery (ACA) territory, middle cerebral artery (MCA) territory, basal ganglia (BG), and/or pons
Post hoc analysis revealed that prefrontal ∆O2Hb during Dual-Task was greater than Walk (p = 0.001; d = 0.79) and Serial7
The objective of this study was to investigate whether task-related changes in prefrontal cortical recruitment measured by Functional near-infrared spectroscopy (fNIRS) are affected by individual differences in people postand people with poor cognitive function would exhibit lower prefrontal recruitment during dual-task walking
Summary
Functional near-infrared spectroscopy (fNIRS) has emerged as a valuable measure for assessing the cortical contributions to locomotor control in both healthy and neurologically impaired populations (Mihara et al, 2007; Holtzer et al, 2011; Clark et al, 2014; Lu et al, 2015; Al-Yahya et al, 2016; Maidan et al, 2016b; Chen et al, 2017; Mirelman et al, 2017; Hawkins et al, 2018; Herold et al, 2018; Mori et al, 2018). Task-related recruitment of prefrontal cortex infers a demand for cognitive/executive control resources, which support attention, working memory, motor planning, and task switching (Yogev-Seligmann et al, 2008; Al-Yahya et al, 2009; Amboni et al, 2013). These cognitive domains play an important role during every day walking in the home and community, especially in challenging environments or under distracted conditions (Suzuki et al, 2004; Yogev-Seligmann et al, 2008; Caliandro et al, 2012; Amboni et al, 2013). The primary hypotheses were that poor mobility function would contribute to prefrontal over-recruitment during typical walking, and that poor cognitive function would contribute to a ceiling in prefrontal recruitment during dual-task walking (i.e., walking with a cognitive task)
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