Analysis of hemodynamics response in prefrontal cortex during motor and cognitive dual-task—fNIR study

Abstract Background Most of the processes occurring in the human body, need brain oxygenation. Motor and cognitive systems require neural resources and during a dual-task performance the demand on the brain increases. This study aimed to analyse the brain activation in static postural control during motor and cognitive dual-tasks. Methods Using Functional near-infrared spectroscopy (fNIR), brain activity (oxygenated hemoglobin concentration ([HbO2]), deoxygenated hemoglobin concentration ([HHb]), oxygenation difference hemoglobin concentration changes (HbOxy = HbO2 – HHb), total hemoglobin (HbTotal = HbO2 + HHb)) were measured in thirty-three young adults (age = 23.12 ± 3.86 years, mean ± SD) during three conditions: in a postural task, quiet standing (single motor task), quiet standing while performing a concurrent motor task - answer the smartphone (motor dual-task) and quiet standing while performing a concurrent cognitive task—arithmetic and memory tasks (cognitive dual-task). After data processing, the Wilcoxon signed-rank test was used for comparison. Results We found increased [HbO2] in young adults while performing cognitive dual-task compared to the single motor task and motor dual-task (P < 0.05). HbOxy differences between cognitive and motor dual-task were found (P < 0.05). No significant differences between single and motor dual-task in [HbO2] were observed. Conclusions Hemodynamic activity in the prefrontal cortex was significantly increased in cognitive dual-task compared to the single motor task. Pre-frontal hemodynamics appear not to be influenced by the number of motor tasks performed while the opposite occurs for the cognitive ones which may arise because the demand in the prefrontal cortex is greater in cognitive tasks while during the motor tasks the [HbO2] is recruited elsewhere.