Different amplitude of auditory N1m evoked by a tone

It is well known that the shape of auditory N1m waveform depends on the property of auditory stimulus. Besides, it has been reported that reactions of the neurons in the auditory cortex of monkey can be affected by the motor task required as a reaction to auditory stimuli [1]. Furthermore, it has been also shown that the motor cortex can receive direct inputs from sensory auditory thalamic nuclei [2]. And, in MEG study, Endo et al. [3] showed that there was an information flow without cognitive processing from visual stimulus processing to the activation of the motor cortex. These studies indicate that the sensory cortex relates to the motor cortex more directly and inseparably than considered traditionally. In these backgrounds, the objective of this study was to examine how the auditory cortex can be affected by the motor cortex. For this purpose, we investigated what changes of the waveform of N1m were observed when subjects performed different unilateral finger reactive movement tasks to auditory stimulus.