Trial-to-trial variability differs between low versus high responders in motor imagery: Near-infrared spectroscopy study

Trial-to-trial variability is a well-known issue in brain signals measured by functional near-infrared spectroscopy (fNIRS) and other modalities. The aim of this study was to quantitatively characterize the variations from trial-to-trial. We recorded fNIRS during motor imagery (MI) and motor execution (ME) in a virtual reality (VR) system. The results of the averaged Δ[O2Hb] fNIRS responses during the two tasks showed that two distinct groups could be differentiated: low responders (LR) and high responders (HR). Within these groups, distinct oxygenation pattern of trial-to-trial variability were identified. Our findings show a relationship of trial-to-trial variability to individual performance in MI, which may be of significance for applications of MI in neurorehabilitation.