Present address: Department of Neuropsychology, 3801 rue University Montréal, Québec, Canada, H3A 2B4.
Hemispheric asymmetry for spectral and temporal processing in the human antero-lateral auditory belt cortex
Article first published online: 27 SEP 2005
European Journal of Neuroscience
Volume 22, Issue 6, pages 1521–1528, September 2005
How to Cite
Schönwiesner, M., Rübsamen, R. and Von Cramon, D. Y. (2005), Hemispheric asymmetry for spectral and temporal processing in the human antero-lateral auditory belt cortex. European Journal of Neuroscience, 22: 1521–1528. doi: 10.1111/j.1460-9568.2005.04315.x
- Issue published online: 27 SEP 2005
- Article first published online: 27 SEP 2005
- Received 27 April 2005, revised 7 July 2005, accepted 8 July 2005
- auditory cortex;
- auditory information processing;
- functional magnetic resonance imaging;
The present study investigates the acoustic basis of the hemispheric asymmetry for the processing of speech and music. Experiments on this question ideally involve stimuli that are perceptually unrelated to speech and music, but contain acoustic characteristics of both. Stimuli in previous studies were derived from speech samples or tonal sequences. Here we introduce a new class of noise-like sound stimuli with no resemblance of speech or music that permit independent parametric variation of spectral and temporal acoustic complexity. Using these stimuli in a functional MRI experiment, we test the hypothesis of a hemispheric asymmetry for the processing of spectral and temporal sound structure by seeking cortical areas in which the blood oxygen level dependent (BOLD) signal covaries with the number of simultaneous spectral components (spectral complexity) or the temporal modulation rate (temporal complexity) of the stimuli. BOLD-responses from the left and right Heschl's gyrus (HG) and part of the right superior temporal gyrus covaried with the spectral parameter, whereas covariation analysis for the temporal parameter highlighted an area on the left superior temporal gyrus. The portion of superior temporal gyrus in which asymmetrical responses are apparent corresponds to the antero-lateral auditory belt cortex, which has been implicated with spectral integration in animal studies. Our results support a similar function of the anterior auditory belt in humans. The findings indicate that asymmetrical processing of complex sounds in the cerebral hemispheres does not depend on semantic, but rather on acoustic stimulus characteristics.