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Hemispheric asymmetries in phonological processing assessed with probe evoked magnetic fields
A C Papanicolaou1, G F Wilson, C Busch
1Division of Neurosurgery, University of Texas, Medical Branch, Galveston.
The International Journal of Neuroscience
|April 1, 1988
Summary
This study investigated auditory evoked magnetic fields (EFs) during language tasks. Phonological processing significantly reduced early N1m components symmetrically but attenuated later P2m components more in the left hemisphere.
Area of Science:
- Neuroscience
- Auditory Neuroscience
- Cognitive Neuroscience
Background:
- Auditory Evoked Potentials (EPs) and Magnetic Fields (EFs) are used to study auditory processing.
- Previous research suggests the left hemisphere plays a dominant role in language tasks.
Purpose of the Study:
- To investigate the neural correlates of auditory processing during concurrent linguistic tasks.
- To examine hemispheric differences in the processing of auditory stimuli when engaged in phonological tasks.
Main Methods:
- Magnetoencephalography (MEG) was used to record Auditory Evoked Magnetic Fields (EFs) in nine subjects.
- Subjects were presented with tonal stimuli alongside verbal material under two conditions: attending to tones (control) and phonological processing (ignoring tones).
- Analysis focused on the N1m and P2m components of the EFs.
Main Results:
- Both N1m and P2m components were observed, corresponding to N1 and P2 in EPs.
- The amplitude of the N1m component was significantly reduced symmetrically in both hemispheres during phonological processing.
- The P2m component's amplitude was significantly attenuated to a greater degree in the left hemisphere.
Conclusions:
- Linguistic processing interferes with the processing of irrelevant auditory stimuli.
- The findings support the hypothesis of greater left hemisphere involvement in language tasks.
- Hemispheric asymmetry in auditory processing is evident during complex cognitive tasks.