Relationship between sustained unilateral hand clench, emotional state, line bisection performance, and prefrontal cortical activity: A functional near-infrared spectroscopy study

ABSTRACTSustained unilateral hand clenching alters perceptual processing and affective/motivational state, with these alterations presumed to reflect increased hemispheric activity contralateral to the side of motor movement. However, data from electroencephalographic and imaging studies are contradictory regarding the relationship between sustained hand clenching and brain activity. In order to investigate the relationship between brain activity, sustained unilateral hand clenching, and changes in affect and perceptual processing, frontal hemispheric activity was measured via functional near-infrared spectroscopy (fNIRS), using derived O2Hb prior to, during, and post-sustained unilateral hand clench. Participants’ mood and spatial perception were recorded pre- and post-clenching. Sustained unilateral hand clenching altered brain activity and mood, but not spatial perception. Results revealed increased O2Hb bilaterally following sustained unilateral hand clenching, relative to baseline, regardless of hand...