Corticomuscular coherence during upright standing in unilateral transfemoral amputees

TL;DR

This study explores how brain and muscle coordination changes in people with a lower limb amputation during standing, revealing altered sensory feedback and increased cognitive load.

Contribution

The study introduces new insights into corticomuscular coherence changes in unilateral transfemoral amputees during upright standing.

Findings

Amputees showed significant differences in afferent and efferent corticomuscular coherence compared to controls.

Increased power and reduced alpha frequencies in the motor cortex suggest higher cognitive load in amputees.

Visual conditions and dual tasking influenced corticomuscular coherence patterns in amputees.

Abstract

Patients with a lower limb amputation suffer from an impaired balance control and thereby are at a higher risk to fall. To cope with this deficit, they adapt their neuromuscular system by modifying biomechanical and neuromuscular structures. In this study, we investigated changes in corticomuscular coherence between the motor cortex and muscles of the trunk and the intact lower leg. We recorded electroencephalogram (EEG) and electromyogram (EMG) data from 10 unilateral transfemoral amputees and 10 age-matched able-bodied controls during quiet upright stance with eyes open, eyes closed and during dual tasking. To analyse afferent and efferent corticomuscular coherence, directional wavelet coherence between EEG and EMG signals was computed. The corticomuscular coherence analysis showed significant differences between amputees and controls in the afferent and efferent direction and across visual conditions, suggesting differences in the processing of sensory feedback. A power spectral density analysis of the motor cortex contralateral to the amputated leg of amputees showed increased power, as well as a pronounced decrease in alpha frequencies indicating an increased cognitive load. This exploratory study stimulates further hypotheses on how coordination of brain and muscle activity is modulated after a lower limb amputation.

Patients with a lower limb amputation adapt their neuromuscular system to maintain balance. Meyer et al. noted changes in EEG power spectral density and directional corticomuscular coherence between the brain cortex and muscles of the lower body during quiet standing with and without vision and during dual tasking.

Graphical Abstract

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