Assessment of the cerebral cortex during motor task behaviours in adults: a systematic review of functional near infrared spectroscopy (fNIRS) studies.

Functional near infrared spectroscopy (fNIRS) is an emerging tool for non-invasively monitoring the haemodynamic response to brain activation. The technique has been widely adopted to investigate cortical responses during motor tasks in health and disease. This systematic review provides a critical analysis of the research findings in the hope of summating relevant information, identifying consistent outcomes acquired using different spectrometers, clarifying data inconsistencies, and learning from the common challenges across disciplines. The spatiotemporal characteristics, reliability, repeatability and modulation of typical cortical response evoked by motor stimulation are all evaluated in detail. The review assesses the contribution of the technique to advancing our understanding of motor skill learning and control in the context of tasks of everyday living, athletic performance, and recovery from neurological illness. Finally, the limitations of current fNIRS technologies are examined and a series of recommendations for future studies are provided based upon the reviewed literature.