Arousal and skilled motor performance: The mediating role of cerebral cortical dynamics

Despite achievement of a highly skilled level of motor competence, elucidation of the multiple factors contributing to variability of motor performance remains somewhat enigmatic. The inverted-U hypothesis posits moderate levels of arousal as essential to optimal performance; this suggests that arousal may be a key player of this variability. The purpose of this study was to examine the psychophysiological concomitants of moderate as compared to low arousal. Specifically we hypothesized a decrease in coherence between the temporal lobes (T3-verbal-analytical processing & T4-visuo-spatial processing) and the motor planning region (Fz), accompanied by an increase in task performance. Fifteen college undergraduates (9 females, 6 males, mean age = 23.4, SD = 4.22) participated in two days of testing. Day one consisted of 340 trials of a novel visuomotor pointing task to achieve task competency. On the second day, EEG data were recorded during both a Performance Alone (PA) condition vs. a Social-Evaluation and Competition (SE&C) condition, which were counterbalanced. Coherence estimates were subjected to a 2 x 2 ANOVA comparing Condition x Hemisphere; post hoc testing was completed using paired-t tests. The arousal-manipulation check of the two experimental protocols (PA vs. SE&C) provided by the autonomic measures and self-reports indicated an increase from a low to moderate level of arousal during the SE&C condition. There was a statistical interaction between condition and hemisphere revealing reduced coherence during SE&C only between T4-Fz (t(14) = 3.084, p = 0.008). Additionally, there was a increase in motor performance (t(13) = 2.171, p = 0.049). Consistent with the inverted-U hypothesis and our predictions as stated for moderate arousal relative to performing alone, there was a subsequent increase in performance coupled with a decrease in coherence between the visuo-spatial and the motor-planning regions. In light of the significantly improved kinematics, the reduction in networking between these task relevant areas is seen as an adaptive refinement of cortico-cortical communication as one moves from low towards optimal arousal