Pre-movement planning processes in people with congenital mirror movements

Abstract

Objective Pre-movement processes were investigated in people with Congenital mirror movement (CMM), a rare disorder in which bilateral movement (mirroring) occurs in the upper distal extremities (primarily the hands and fingers) during intended unilateral movements. Abnormal density of ipsilateral corticospinal projections is an established hallmark of CMM. This study tested whether the Lateralised Readiness Potential (LRP), which reflects movement planning and readiness, is also abnormal in people with CMM. Methods Twenty-eight neurologically-normal controls and 8 people with CMM were tested on a unimanual Go/No-go task while electroencephalography (EEG) was recorded to assess the LRP. Results No significant group differences were found in reaction time (RT). However, significantly smaller LRP amplitudes were found, on average, in the CMM group compared to Controls at central-motor (C3, C4) sites in stimulus-locked and response-locked epochs; similar group differences were also found at further frontal sites (F3, F4) during response-locked epochs. Conclusions Abnormal brain activity in pre-movement processes associated with response planning and preparation is present in people with CMM. Significance Aberrant bilateral activity during pre-movement processes is clearly implicated; whether part of the etiology of CMM, or as a mechanism of neuro-compensation, is not yet known.