Contra- and Ipsilateral Auditory Stimuli Produce Different Activation Patterns at the Human Auditory Cortex: A Neuromagnetic Study

摘要

Auditory evoked magnetic fields were recorded over the right hemisphere of healthy humans. The stimuli were noise bursts presented either to the contra- (C) or ipsilateral (I) ear in different combinations. The largest deflection of the responses, N100m (Magnetic counterpart of electric N100), showed a field pattern which suggests activation of the supratemporal auditory cortex. In an oddball paradigm, where the standards (90%) were 400-ms noise bursts presented to the contralateral ear, and the deviants (10%) similar stimuli to the ipsilateral ear, the deviants elicited on the average 130% stronger equivalent dipoles of N100m than standards. When two 50-ms noise bursts, separated by 300 ms, were presented once every 2 s, N100m evoked by the second stimulus of the pair was smaller when the stimuli were presented monaurally (C - C or I - I) than to different ears (C - I or I - C). The results suggest that contra- and ipsilateral auditory stimuli are analyzed, at least in part, in different neural networks at the human auditory cortex.