Retinotopic effects during spatial audio-visual integration.

Full Abstract

The successful integration of visual and auditory stimuli requires information about whether visual and auditory signals originate from corresponding places in the external world. Here we report crossmodal effects of spatially congruent and incongruent audio-visual (AV) stimulation. Visual and auditory stimuli were presented from one of four horizontal locations in external space. Seven healthy human subjects had to assess the spatial fit of a visual stimulus (i.e. a gray-scaled picture of a cartoon dog) and a simultaneously presented auditory stimulus (i.e. a barking sound). Functional magnetic resonance imaging (fMRI) revealed two distinct networks of cortical regions that processed preferentially either spatially congruent or spatially incongruent AV stimuli. Whereas earlier visual areas responded preferentially to incongruent AV stimulation, higher visual areas of the temporal and parietal cortex (left inferior temporal gyrus [ITG], right posterior superior temporal gyrus/sulcus [pSTG/STS], left intra-parietal sulcus [IPS]) and frontal regions (left pre-central gyrus [PreCG], left dorsolateral pre-frontal cortex [DLPFC]) responded preferentially to congruent AV stimulation. A position-resolved analysis revealed three robust cortical representations for each of the four visual stimulus locations in retinotopic visual regions corresponding to the representation of the horizontal meridian in area V1 and at the dorsal and ventral borders between areas V2 and V3. While these regions of interest (ROIs) did not show any significant effect of spatial congruency, we found subregions within ROIs in the right hemisphere that showed an incongruency effect (i.e. an increased fMRI signal during spatially incongruent compared to congruent AV stimulation). We interpret this finding as a correlate of spatially distributed recurrent feedback during mismatch processing:
whenever a spatial mismatch is detected in multisensory regions (such as the IPS), processing resources are re-directed to low-level visual areas.

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Author information

Author/s: Meienbrock, A (A); Naumer, M J (MJ); Doehrmann, O (O); Singer, W (W); Muckli, L (L);

Affiliation: Max Planck Institute for Brain Research, Department of Neurophysiology, Frankfurt/Main, Germany.

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't

Journal: Neuropsychologia (Neuropsychologia), published in England. (Language: eng)

Reference: 2007-Feb; vol 45 (issue 3) : pp 531-9

Dates: Created 2006/12/18; Completed 2007/03/27;

PMID: 16797610, 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
Adult
Auditory Perception - physiology
Brain Mapping
Eye Movements - physiology
Female
Functional Laterality
Humans

Image Processing, Computer-Assisted - methods
Magnetic Resonance Imaging - methods
Male
Oxygen - blood
Photic Stimulation - methods
Space Perception - physiology
Visual Pathways - blood supply; physiology
Visual Perception - physiology

Associated Chemicals: Oxygen (7782-44-7)

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