Early cross-modal interactions in auditory and visual cortex underlie a sound-induced visual illusion.

Full Abstract

When a single flash of light is presented interposed between two brief auditory stimuli separated by 60-100 ms, subjects typically report perceiving two flashes (Shams et al., 2000, 2002). We investigated the timing and localization of the cortical processes that underlie this illusory flash effect in 34 subjects by means of 64-channel recordings of event-related potentials (ERPs). A difference ERP calculated to isolate neural activity associated with the illusory second flash revealed an early modulation of visual cortex activity at 30-60 ms after the second sound, which was larger in amplitude in subjects who saw the illusory flash more frequently. These subjects also showed this early modulation in response to other combinations of auditory and visual stimuli, thus pointing to consistent individual differences in the neural connectivity that underlies cross-modal integration. The overall pattern of cortical activity associated with the cross-modally induced illusory flash, however, differed markedly from that evoked by a real second flash. A trial-by-trial analysis showed that short-latency ERP activity localized to auditory cortex and polymodal cortex of the temporal lobe, concurrent with gamma bursts in visual cortex, were associated with perception of the double-flash illusion. These results provide evidence that perception of the illusory second flash is based on a very rapid dynamic interplay between auditory and visual cortical areas that is triggered by the second sound.

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Author information

Author/s: Mishra, Jyoti (J); Martinez, Antigona (A); Sejnowski, Terrence J (TJ); Hillyard, Steven A (SA);

Affiliation: Division of Biological , University of California, San Diego, La Jolla, California 92093, USA.

Grants: EY01698432 (Agency:NEI NIH HHS)

Journal and publication information

Publication Type: Comparative Study; Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't

Journal: The Journal of neuroscience : the official journal of the Society for Neuroscience (J Neurosci), published in United States. (Language: eng)

Reference: 2007-Apr; vol 27 (issue 15) : pp 4120-31

Dates: Created 2007/04/12; Completed 2007/05/03; Revised 2007/12/03;

PMID: 17428990, status: MEDLINE (last retrieval date: 12/26/2008)

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Acoustic Stimulation - methods
Auditory Cortex - physiology
Auditory Perception - physiology
Evoked Potentials - physiology
Female
Humans

Illusions - physiology; psychology
Male
Photic Stimulation - methods
Psychomotor Performance - physiology
Reaction Time - physiology
Visual Cortex - physiology

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