Simultaneous bilateral mismatch response to right- but not leftward sound lateralization

Area of Science:

• Auditory Neuroscience
• Neuroimaging
• Hemispheric Specialization

Background:

• Understanding how the brain processes auditory spatial information is crucial for comprehending perception.
• Previous research suggests potential hemispheric asymmetries in auditory processing, but direct comparisons of location mismatch responses are limited.

Purpose of the Study:

• To investigate interhemispheric differences in mismatch responses to changes in sound-source direction using magnetoencephalography (MEG).
• To compare the processing of right- and left-lateralized auditory spatial deviants.

Main Methods:

• Sixteen adults participated in a passive listening experiment using complex non-language sounds.
• Magnetoencephalography (MEG) recorded brain activity during the presentation of midline standards with right- and left-lateralized deviants.
• A second experiment used spectral deviants to isolate location processing.

Main Results:

• Mismatch dipole amplitudes were significantly larger contralateral than ipsilateral to the sound deviants.
• Both hemispheres processed right-deviant sounds simultaneously, but the left hemisphere showed a 20 ms delay in processing left-deviant sounds compared to the right hemisphere.
• No interhemispheric differences were observed for spectral deviants, with longer mismatch latencies.

Conclusions:

• The findings suggest fast, contralaterally dominant location mismatch responses.
• Auditory spatial deviance detection appears to be facilitated in the right hemifield, indicating a right-hemisphere advantage for processing sound location changes.
• These results contribute to understanding the neural basis of auditory spatial perception and hemispheric specialization.