Changes in Cortical Activation During Dual-Task Walking in Individuals With and Without Visual Vertigo

Abstract

Background and Purpose: Persons with vestibular disorders are known to have slower gait speed with greater imbalance and veering during dual-task walking than healthy individuals, but the cerebral mechanisms are unknown. The purpose of this study was to determine whether individuals with visual vertigo (VV) have different cerebral activation during dual-task walking compared with control subjects. Methods: Fourteen individuals with VV and 14 healthy controls (CON) were included (mean 39 years old, 85% women). A cross-sectional experimental study consisting of 4 combinations of 2 surfaces (even and uneven) and 2 task conditions (single- and dual-task) was performed. Participants walked over an even (level flooring) or uneven (wood prisms underneath carpeting) surface, either quietly or while reciting every other letter of the alphabet. Changes in cerebral activation over the bilateral prefrontal cortices were recorded using functional near-infrared spectroscopy during 4 task conditions relative to quiet standing. Gait speed and cognitive performance were recorded. Results: There were no between-group differences in cognitive performance. Both groups slowed when walking on an uneven surface or performing a dual-task; participants in the VV group walked more slowly than those in the CON group in all conditions. Participants with VV had decreased cerebral activation in the bilateral prefrontal regions in comparison to CON participants in all conditions. Discussion and Conclusions: Participants with VV had lower prefrontal cortex activation than CON participants during dual-task walking. Lower cortical activity in those with VV may be due to shifted attention away from the cognitive task to prioritize maintenance of dynamic balance. Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A303).

Analysis methods for measuring passive auditory fNIRS responses generated by a block-design paradigm

“… 50 , 52 Briefly, this approach to short-channel regression subtracts a scaled version of the signal obtained from the nearest short channel from the signal obtained from the long channel. The modified Beer–Lambert law was then applied, with a partial pathlength factor of 0.1, 64 – 66 converting the optical-density measurements to changes in hemoglobin concentration. Next, channels with source-detector separations outside the range of 20 to 40 mm were excluded, followed by application of the signal-improvement algorithm based on the negative correlation between oxygenated and deoxygenated hemoglobin dynamics.…”

Characterization of Mayer-wave oscillations in functional near-infrared spectroscopy using a physiologically informed model of the neural power spectra

“…The data were then converted to hemoglobin concentration using the modified Beer-Lambert law with a partial pathlength factor of 0.1. [25][26][27] Channels with a source-detector distance of less than 1.5 or greater than 4.5 cm were excluded from further analysis. Finally, as the oxyhemoglobin measurement contains a greater contribution from Mayer-wave signals than deoxyhemoglobin, 8 only the oxyhemoglobin signal was retained for further analysis.…”

The Immediate Effects of Intermittent Theta Burst Stimulation of the Cerebellar Vermis on Cerebral Cortical Excitability During a Balance Task in Healthy Individuals: A Pilot Study

“…Moreover, the cortical neural activity results obtained from fNIRS were similar to that from functional MRI (fMRI). The fNIRS is a useful tool that has been applied to record brain activation during balance tasks in previous study ( Hoppes et al, 2020 ). Previous works by our research group have demonstrated that iTBS of the cerebellar hemisphere could improve balance and gait in patients with cerebral stroke.…”