Bilateral waveform dissimilarity of auditory evoked potentials may reveal a lateralized motor response process: a correlation method.

A modified correlation method was applied to AEPs under a choice reaction task to distinguish hemispheric influences on motor versus stimulus processing. The subjects were 16 right-handed males (age: 19-30). The task was to press the micro-switch with the right index finger as quickly as possible to 2,000 Hz tone pips (GO) but not to press to 1,500 Hz (NO GO). Active electrodes were placed bilaterally on C3 and C4, according to the 10-20 system and linked-ear electrodes were used as a reference. EEGs triggered by the auditory stimuli were summated 100 times and the obtained AEPs were mainly analyzed by a modified correlation method. The results were as follows; 1. the mean choice reaction time was 332 +/- 83 msec, 2. examined by a modified correlation method, there were significant differences between GO and NO GO at the latencies of 200-300 msec. There is a possibility that these intervals when significant differences were seen by a modified correlation method may relate to a motor response process.