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Abstract
The goal of the present study was to further our understanding of how attention directed
to carrier frequency changes in amplitude-modulated tones (AM) affects the auditory
steady-state response (ASSR).
ASSR in the 40-Hz range were recorded in 15 adults using the frequency tagging method
while subjects detected a carrier frequency change in amplitude-modulated tones. Spectral
and temporal domain analyses were performed to examine the effect on response amplitudes
during attending to the tones compared to ignoring them for both monaural and dichotic
stimulations.
Larger responses were found in the hemisphere contralateral to the stimulated ear.
Binaural suppression for ipsilateral input was found in both hemispheres. Time series
of the source waveforms were calculated from equivalent current dipoles and showed
a 2Hz beat for the dichotic presentation. Attention to carrier frequency change was
significant only during dichotic presentation where larger right hemisphere responses
were found at the onset of carrier change.
Attending to carrier frequency change in stimulation enhances the right hemisphere
ASSR amplitude for dichotic stimulation.
The possibility of tagging frequency specific responses up to auditory cortex makes
the ASSR approach interesting for studying hearing impairment mechanisms, integrity
of auditory structures and attention.
Copyright (c) 2009 International Federation of Clinical Neurophysiology. Published
by Elsevier Ireland Ltd. All rights reserved.