Distinct gamma-band evoked responses to speech and non-speech sounds in humans

Palva, S. , Palva, J. M. , Shtyrov, Y., Kujala, T., Ilmoniemi, R. J., Kaila, K. and Näätänen, R. (2002) Distinct gamma-band evoked responses to speech and non-speech sounds in humans. Journal of Neuroscience, 22(4), RC211. (doi: 10.1523/JNEUROSCI.22-04-j0003.2002) (PMID:11844845)

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To understand spoken language, the human brain must have fast mechanisms for the representation and identification of speech sounds. Stimulus-induced synchronization of neural activity at gamma frequencies (20-80 Hz), occurring in humans at 200-300 msec from stimulus onset, has been suggested to be a possible mechanism for neural object representation. Auditory and visual stimuli also evoke an earlier (peak <100 msec) gamma oscillation, but its dependence on high-level stimulus parameters and, thereby, its involvement in object representation has remained unclear. Using whole-scalp magnetoencephalography, we show here that responses evoked by speech and non-speech sounds differed in the gamma-frequency but not in the low-frequency (0.1-20 Hz) band as early as 40-60 msec from stimulus onset. The gamma-band responses to the speech sound peaked earlier in the left than in the right hemisphere, whereas those to the non-speech sound peaked earlier in the right hemisphere. For the speech sound, there was no difference in the response amplitude between the hemispheres at low (20-45 Hz) gamma frequencies, whereas for the non-speech sound, the amplitude was larger in the right hemisphere. These results suggest that evoked gamma-band activity may indeed be sensitive to high-level stimulus properties and may hence reflect the neural representation of speech sounds. Consequently, speech-specific neuronal processing may commence no later than 40-60 msec from stimulus onset, possibly in the form of activation of language-specific memory traces.

Item Type:Articles
Additional Information:This work was supported by the Academy of Finland, the Finnish Cultural Foundation, and the Juselius Foundation of Finland.
Glasgow Author(s) Enlighten ID:Palva, Professor Satu and Palva, Professor Matias
Authors: Palva, S., Palva, J. M., Shtyrov, Y., Kujala, T., Ilmoniemi, R. J., Kaila, K., and Näätänen, R.
College/School:College of Medical Veterinary and Life Sciences > School of Psychology & Neuroscience
Journal Name:Journal of Neuroscience
Publisher:Society for Neuroscience
ISSN (Online):1529-2401

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