Influence of fatigue on reaction times and corticospinal excitability during movement preparation

Slower self-selected ballistic movement speeds and reduced corticospinal excitability at rest are associated with post-stroke fatigue (PSF). It is unclear if fatigue-related differences in corticospinal excitability, measured using transcranial magnetic stimulation, prior to a movement will explain slower movement speeds. We hypothesized that the levels of PSF explains the modulation of corticospinal excitability during movement preparation and altered behaviour. In this study, 73 non-depressed, high functioning, chronic, first-time stroke survivors performed a simple warned and unwarned auditory reaction time task. We show a reduced suppression of corticospinal excitability during movement preparation, an increased facilitation immediately prior to movement onset and slower reaction times in those with greater levels of PSF. Reduced suppression and increased facilitation of corticospinal excitability prior to movement onset in high fatigue is an indicator of poor modulation of pre- movement excitability which may in turn reflect poor sensory processing, supporting the sensory attenuation model of fatigue.