Do movement-related beta oscillations change after stroke?

Holly E Rossiter,Nick S Ward,Marie-Hélène Boudrias

doi:10.1152/jn.00345.2014

Holly E Rossiter, Nick S Ward + Show 1 more

Open Access

https://doi.org/10.1152/jn.00345.2014

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Abstract

Stroke is the most common cause of physical disability in the world today. While the key element of rehabilitative therapy is training, there is currently much interest in approaches that “prime” the primary motor cortex to be more excitable, thereby increasing the likelihood of experience-dependent plasticity. Cortical oscillations reflect the balance of excitation and inhibition, itself a key determinant of the potential for experience-dependent plasticity. In the motor system, beta-band oscillations are important and are thought to maintain the resting sensorimotor state. Here we examined motor cortex beta oscillations during rest and unimanual movement in a group of stroke patients and healthy control subjects, using magnetoencephalography. Movement-related beta desynchronization (MRBD) in contralateral primary motor cortex was found to be significantly reduced in patients compared with control subjects. Within the patient group, smaller MRBD was seen in those with more motor impairment. We speculate that impaired modulation of beta oscillations during affected hand grip is detrimental to motor control, highlighting this as a potential therapeutic target in neurorehabilitation.

Highlights

STROKE IS THE MOST COMMON cause of physical disability in the world today
We investigated how motor cortex beta oscillations are affected in stroke patients with a range of impairments and at different times after stroke
We report two new key findings: First, contralateral M1 Movement-related beta power decrease (MRBD) was diminished in patients compared with control subjects, there was no difference in baseline beta power between groups

Summary

Introduction

STROKE IS THE MOST COMMON cause of physical disability in the world today. While the key element of rehabilitative therapy is training, there is currently much interest in approaches that “prime” the primary motor cortex (M1) to be more excitable, thereby increasing the likelihood of experience-dependent plasticity (Hagemann et al 1998). Movement-related beta power decrease (MRBD) has been linked to M1 excitability in recent EEG-TMS studies (Aono et al 2013; Takemi et al 2013), and both the strength and frequency of oscillations are influenced by levels of the inhibitory neurotransmitter GABA (Hall et al 2010; Muthukumaraswamy et al 2009, 2012) These results suggest that MEG might be a useful tool for studying the balance between inhibition and excitation in the human cortex. Previous studies have explored oscillatory parameters at rest and during tactile stimulation (Laaksonen et al 2012; Tecchio et al 2007a, 2007b), but currently there is little information on how these oscillations change during movement of affected limbs after stroke. We hypothesized that beta oscillations would be diminished after stroke both at rest and during movement and that this would be more apparent in those with greater impairment

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