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Activity in multiple frontal cortical areas during normal, fast and dual task walking: preliminary results of an fNIRS study.

Lookup NU author(s): Rodrigo Vitorio, Dr Lisa Alcock, Dr Sam Stuart, Professor Emidio Silva, Professor Lynn Rochester, Dr Annette Pantall

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Abstract

BACKGROUND AND AIM: Most previous studies using functional near-infrared spectroscopy (fNIRS) during walking have assessed the prefrontal cortex only. However, recording of multiple cortical areas allows identification of potential compensatory or other cortical mechanisms related to increased cognitive, sensory and/or motor demands of walking. This study aimed to investigate the activity in multiple frontal cortical areas during normal, fast and dual task walking.METHODS: Ten healthy adults aged from 18 to 31 years performed three 5-minute blocks of alternating tasks (control and experimental) on a treadmill. For each block, tasks were performed for 30 seconds and repeated five times. Tasks included normal walking (at comfortable speed), fast walking (20% faster than normal walking) and dual task walking (walking while performing a memory task). An fNIRS system (OMM-3000, Shimadzu, Kyoto, Japan) with continuous wave laser diodes with wavelengths of 780, 805 and 830 nm recorded cortical activity with a sampling rate of 23.8 Hz. A 40-channel arrangement with 25 optodes (5 x 5), consisting of 13 transmitters and 12 detectors, covered an area 12×12 cm overlying the frontal lobe. Areas assessed included prefrontal cortex, premotor cortex, supplementary motor area and primary motor cortex. Data were pre-processed using Statistical Parametric Mapping (Wellcome Trust Centre for Neuroimaging). Analysis of oxygenated haemoglobin signal was performed using a customized code implemented in MatLab (The MathWorks, Inc). For each task, the period of interest was defined as the middle 20 s (initial and final 5 s were excluded), which were split into early (5-15 s) and late (15-25 s) phases. The averaged normalised difference between control and experimental task was used for statistical analysis (one sample T-tests with Bonferroni correction for multiple comparisons).RESULTS: Relative to standing still, normal walking increased cortical activation in all areas assessed during the early phase. During the subsequent late phase of normal walking, activation decreased and returned to the level of standing still in all areas assessed. No significant differences were observed between normal and fast walking. During dual task walking, the primary motor cortex was the only area that increased activation, which occurred during both early and late phases.CONCLUSIONS: These findings suggest that in healthy young adults increased activity of frontal cortical areas is necessary for walking initiation and adapting to the desired speed but not for steady state walking. No further activation of frontal cortical areas is required for fast walking. Increased activation of the primary motor cortex is required to deal with increased cognitive demand of dual task walking. This novel finding questions the simplistic view of the human primary motor cortex as a purely executive motor structure and suggests an association with cognitive and/or attentional processes during walking.


Publication metadata

Author(s): Vitorio R, Alcock L, Stuart S, Lirani-Silva E, Rochester L, Pantall A

Publication type: Conference Proceedings (inc. Abstract)

Publication status: Published

Conference Name: World Congress of the International Society for Posture and Gait Research

Year of Conference: 2017

Print publication date: 25/06/2017

Online publication date: 25/06/2017

Acceptance date: 25/06/2017


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