Browsing by Author "Lambrechts, M."
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- ItemIdentification of wine yeast strains with FT-NIRS and effect of spectral variation due to sample preparation and repeated analyses(2007) Muller, C. A.; Manley, M.; Lambrechts, M.; Pretorius, I. S.; Nieuwoudt, Helene
- ItemInvestigating the frontal cortex of the brain of a young and apparently healthy population during human locomotion, with a cognitive load - An EEG study.(Stellenbosch : Stellenbosch University, 2021-12) Lambrechts, M.; Van den Heever, D.; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.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.