Reaction time to an auditory stimulus in the sympathetic activation phase of the ultradian rhythm

An increase in alternative activation in cerebral lateralisation with the ultradian rhythm dominates sympathetic or parasympathetic phases. In this study, we tested the reaction time (RT) of right-handed younger people to an auditory stimulus by shifting the ultradian rhythm to the sympathetic activation (SA) period. Twenty-three women and 7 men students volunteered for our study. In the resting period and SA phase, after measuring the participants’ blood pressure, heart rate, and nasal dominance, we assessed their right and left-hand RTs against regular and irregular auditory stimuli. SA was provided by running for 5 minutes on a treadmill at a rate that doubled the resting heart rate. In the SA phase, right-and left-hand RTs were accelerated in both stimulus types compared to pre-exercise (p.05). However, with irregular stimuli, the left-hand RT was faster than the right-hand RT for the resting period and after SA (p<.01). We conclude that the known superiority of the right hemisphere in processing non-verbal sounds, and its greater functionality in the formation of attention compared with the left hemisphere, accelerated the left-hand RT against irregular stimuli. Although the right hand and the motor area of the left hemisphere have an advantage of learned automatic motor skills, we suppose that the right hemisphere is superior in reaching the non-verbal sounds to the auditory cortex and the right auditory cortex processes these sensory signals faster via short-cut pathways.