Investigating the frontal cortex of the brain of a young and apparently healthy population during human locomotion, with a cognitive load - An EEG study.

Thesis (MEng)--Stellenbosch University, 2021.ENGLISH ABSTRACT: Walking forms a fundamental part of our everyday life. Since recently, walking was assumed an automatic function that does not require cognitive input. Studies have been done investigating this statement by using the dual task walking paradigm (walking with a concurrent secondary task). Findings of these studies shows that gait and brain behaviour is modulated during dual tasking, indicating that walking does require cognitive input, specifically attention, and is not only automatic. Despite these studies, there is still a lack of information regarding the brain’s involvement during human locomotion and how the brain and gait is impacted during dual task walking. This research study aimed to investigate how gait performance changed during dual task walking, specifically walking while simultaneously executing a cognitive task (i.e., cognitive interference) and to observe how the brain behaviour is modulated. The study developed an experiment where the participants gait characteristics and brain activity was measured using the Vicon MX motion capture system (for kinematic data), a treadmill with embedded force plates (for spatial temporal data) and electroencephalographic (EEG) (for brain activity), during normal walking and dual task walking. The gait characteristics were evaluated, with regards to postural control and gait consistency, and compared for both conditions. The brain activity was evaluated, with regards to frequency activity in the alpha and beta band and compared during both conditions. The performance, including accuracy and response time, of the Flanker task during walking and standing were also evaluated and compared. The P300 wave of the event-related potential, with regards to latency and amplitude, were also evaluated and compared for dual task walking and performing the Flanker task while standing. The performance of the Flanker task showed no significant differences for accuracy or response times. The spatial temporal measures included cadence, cadence variability, stride length and stride length variability. A much slower cadence was observed and a higher cadence variability, during dual task walking, proving that the gait inconsistency was higher. For stride length, no significant differences were found. The kinematic measures included ankle dorsiflexion, knee, and hip flexion, and center of mass. No significant differences were found for ankle dorsiflexion. Significant differences were found for hip and knee flexion and the center of mass, indicating greater adaption of the lower-limb body was required during dual task walking. The frequency activity was evaluated for Fp1 and Fp2 (corresponding to executive function and attention) and Cz (corresponding to motor control). In the alpha band, a decrease in activity was found during dual task walking, which is indicative of an increase in cognitive load. However, a decrease in beta activity was found, contradicting to previous studies which found an increase. Lastly, an increase in the P300 amplitude was found, indicative of an increase in attention demand, and a longer latency of the P300 wave, indicative of poorer mental performance, during dual task walking. These findings shows that brain activity is modulated, and gait performance decreases, during dual task walking, indicating that walking is not only an automatic function but does require attention as well.AFRIKAANSE OPSOMMING: Loop is ‘n belangrikke deel van mens se elkedag lewe. Tot onlangs was loop aanvaar as ‘n automatiese funksie wat geen kognitiewe insette benodig nie. Studies word onlangs gedoen wat hierdie stelling ondersoek deur gebruik te maak van die “dual task walking paradigm”, wat beteken om te loop en terselfdetyd ‘n sekondêre taak uit te voer. Die bevindings van hierdie studies wys dat loop en brein gedrag word gemoduleer tydens hierdie kondisie, wat aandui dat loop kognitiewe insette benodig, spesifiek aandag, en nie net automaties gebeur nie. Behalwe vir hierdie studies, is daar steeds ‘n gebrek aan informasie in verband met die betrokkenheid van die brein tydens loop asook hoe die brein en loop ge-impak word as gevolg van die sekondêre taak. Hierdie navorsing studie se doel was om te ondersoek hoe loop verander tydens loop met ‘n sekondêre taak, wanneer die sekondêre taak ‘n kognitiewe taak is, en om te ondersoek hoe die brein se gedrag gemoduleer word. ‘n Eksperiment was ontwerp waar deelnemers se loop eienskappe en brein aktiwiteit gemeet word met “Vicon MX motion capture system”, vir kinematiese data, en ‘n automatiese loopplank met ingeboude kragplate, vir ruim-tyd data, en “electroencephalogram”, vir brein aktiwiteit tydens loop en loop met ‘n sekondêre taak. Loop eienskappe was ge-evalueer met betrekking tot postuur kontrole en loop teenstrydighede vir beide kondisies. The brein aktiwiteit was ge-evalueer met betrekking tot die frekwensie aktiwiteit in die beta an alfa band. Die prestasie van die kognitiewe taak was ge-evalueer met betrekking tot akkuraatheid en reaksietyd. Die P300 breinpotensiaal met betrekking tot sterkte en tyd was ge-evalueer vir net die sekondêre taak asook loop met die sekondêre taak. Die prestasie resultate het geen beduindende verskille gewys tussen net die sekondêre taak en loop met ‘n sekondêre taak nie. Die ruim-tyd resultate het ingesluit loop spoed, loop spoed veranderlikheid, stap lengte en stap lengte veranderlikheid. ‘n Baie stadiger loop spoed en ‘n hoër loop spoed veranderlikheid was waargeneem vir loop en ‘n sekondêre taak doen terselfdetyd, wat ‘n aanduiding is dat die konsekwentheid van loop slegter is tydens loop met ‘n sekondêre taak. Geen beduidende verskille was gevind vir stap lengte nie. Die kinematiese resultate het ingesluit enkel hoek, knie en heup hoek en massamiddelpunt. Geen beduidende verskille was gevind vir die enkel hoeke nie. Beduidende verskille was gevind vir die knie, heup en massamiddelpunt, wat aandui groter aanpassings in die onderlyf moes gemaak word tydens loop en ‘n sekondêre taak terselfdetyd. Die frekwensie aktiwiteit was ge- evalueer vir Fp1 en Fp2 (ooreenstemmend met uitvoerende funskie en aandag) en Cz (ooreenstemmend met motor funksie). Vir die alfa band, ‘n afneming in aktiwiteit was gevind gedurende loop met ‘n sekondêre taak, wat ‘n aanduiding is van ‘n toename in kognitiewe lading. Vir die beta band, ‘n afneming in aktiwiteit was gevind, wat teenstrydig is met vorige studies wat ‘n toename gevind het. Laastens, ‘n toename in die P300 potensiaal was gevind, wat ‘n aanduiding is tot ‘n toename in aandag lading, en ‘n langer tyd vir die P300 potensiaal, wat ‘n aanduiding is van slegter verstandelike prestasie tydens loop met ‘n sekondêre taak. Hierdie bevindings wys dat brein gedrag word gemoduleer en loop prestasie neem af gedurende loop met ‘n sekondêre taak, wat aandui dat loop nie net automaties gebeur nie, maar wel kognitiewe insette (spesifiek aandag) benodig.Master