Some of these data have been presented in abstract form at the 8th annual meeting of the International Multisensory Research Forum (IMRF), Sydney, Australia, July 4–8, 2007.
Onset timing of cross-sensory activations and multisensory interactions in auditory and visual sensory cortices
Article first published online: 11 MAY 2010
© The Authors (2010). Journal Compilation © Federation of European Neuroscience Societies and Blackwell Publishing Ltd
European Journal of Neuroscience
Special Issue: MULTISENSORY PROCESSES
Volume 31, Issue 10, pages 1772–1782, May 2010
How to Cite
Raij, T., Ahveninen, J., Lin, F.-H., Witzel, T., Jääskeläinen, I. P., Letham, B., Israeli, E., Sahyoun, C., Vasios, C., Stufflebeam, S., Hämäläinen, M. and Belliveau, J. W. (2010), Onset timing of cross-sensory activations and multisensory interactions in auditory and visual sensory cortices. European Journal of Neuroscience, 31: 1772–1782. doi: 10.1111/j.1460-9568.2010.07213.x
- Issue published online: 17 MAY 2010
- Article first published online: 11 MAY 2010
- Received 5 October 2009, revised 12 January 2010, accepted 15 January 2010
- audiovisual interactions;
- auditory cortex;
- visual cortex
Here we report early cross-sensory activations and audiovisual interactions at the visual and auditory cortices using magnetoencephalography (MEG) to obtain accurate timing information. Data from an identical fMRI experiment were employed to support MEG source localization results. Simple auditory and visual stimuli (300-ms noise bursts and checkerboards) were presented to seven healthy humans. MEG source analysis suggested generators in the auditory and visual sensory cortices for both within-modality and cross-sensory activations. fMRI cross-sensory activations were strong in the visual but almost absent in the auditory cortex; this discrepancy with MEG possibly reflects the influence of acoustical scanner noise in fMRI. In the primary auditory cortices (Heschl’s gyrus) the onset of activity to auditory stimuli was observed at 23 ms in both hemispheres, and to visual stimuli at 82 ms in the left and at 75 ms in the right hemisphere. In the primary visual cortex (Calcarine fissure) the activations to visual stimuli started at 43 ms and to auditory stimuli at 53 ms. Cross-sensory activations thus started later than sensory-specific activations, by 55 ms in the auditory cortex and by 10 ms in the visual cortex, suggesting that the origins of the cross-sensory activations may be in the primary sensory cortices of the opposite modality, with conduction delays (from one sensory cortex to another) of 30–35 ms. Audiovisual interactions started at 85 ms in the left auditory, 80 ms in the right auditory and 74 ms in the visual cortex, i.e., 3–21 ms after inputs from the two modalities converged.