AUTHOR=Meester Daan , Al-Yahya Emad , Dawes Helen , Martin-Fagg Penny , Piñon Carmen 

TITLE=Associations between prefrontal cortex activation and H-reflex modulation during dual task gait

JOURNAL=Frontiers in Human Neuroscience

VOLUME=Volume 8 - 2014

YEAR=2014

URL=https://www.frontiersin.org/journals/human-neuroscience/articles/10.3389/fnhum.2014.00078

DOI=10.3389/fnhum.2014.00078

ISSN=1662-5161

ABSTRACT=Walking, although a largely automatic process, is controlled by the cortex and the spinal cord; with corrective reflexes modulated through integration of neural signals from central and peripheral inputs at supraspinal level throughout the gait cycle. However the full mechanism is not described. In this study we used an additional cognitive task to interfere with the automatic processing during walking in order to explore the neural mechanisms involved in healthy young adults. Participants were asked to walk on a treadmill at two speeds, both with and without additional cognitive load. We evaluated the impact of speed and cognitive load by analysing activity of the pre-frontal cortex (PFC) using functional Near-Infrared Spectroscopy (fNIRS) alongside with spinal cord reflex activity measured by soleus H-reflex amplitude and gait changes obtained by using an inertial measuring unit. Repeated measures ANOVA revealed that fNIRS Oxy-Hb concentrations significantly increased in the PFC with dual task (walking while performing a cognitive task) compared to a single talk only (walking) (p< 0.05). PFC activity was unaffected by increases of walking speed. H-reflex amplitude and gait variables did not change in response to either dual task or increases of walking speed. When walking under additional cognitive load we observed that participants adapted by using greater activity in the PFC, but that this adaption did not detrimentally affect H-reflex amplitude or gait variables. Our findings suggests that in a healthy young population central mechanisms (PFC) are activated in response to cognitive loads but that H-reflex activity and gait performance can successfully be maintained. This study provides insight in the mechanisms behind healthy individuals safely performing dual task walking