Crossmodal Audio-Visual Integration In The Human Auditory and Visual Cortices Revealed By Magnetoencephalography.
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1
'G. D'Annunzio' University, ITAB and Department of Clinical Sciences and Bioimaging, Italy
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2
'G. D'Annunzio' University, Dipartimento di Scienze Biomediche, Italy
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3
University of Chieti , ITAB, Italy
Behavioural responses to multimodal inputs presented in close spatial and temporal proximity are typically faster and more accurate than those to unimodal stimuli alone [1]. Multimodal integration was studied in ten subjects by presenting sequences of auditory (brief tone, unimodal audio condition), visual (stroboscopic alternate motion of flashes, unimodal visual) and audio-visual (tones and stroboscopic flashes) stimuli during magnetoencephalographic recording. In the audio-visual condition tones and flashes were randomly presented using three different levels of asynchrony between onset of audio and visual stimuli: 0, 90 and 180 ms. The subjects’ task was to indicate if the audio and visual stimuli were perceived as temporally synchronous or asynchronous. The aim of the present study was to evaluate possible enhancement or inhibition phenomena between auditory and visual regions during crossmodal audio-visual stimulation. Neural responses in the auditory and visual cortices were investigated for each of the two unimodal stimuli presented in isolation and for the three asynchrony levels of bimodal presentations. MEG results showed no significant difference between unimodal and 180 ms condition in the peak latency and amplitude of the dipoles in the auditory and visual cortices. Slower activations were instead found in the 0 ms than the unimodal audio and visual conditions evidencing a delayed mechanism in the auditory and visual cortices when the two inputs were synchronous. On the contrary the effect of the 90 ms condition was different for the auditory and visual areas when compared to the unimodal ones. A facilitation mechanism was found in the auditory cortex, whereas in the visual cortex the activation was delayed.
References
1. McDonald JJ, Teder-Salejarvi WA, Hillyard SA. (2000) Involuntary orienting to sound improves visual perception. Nature 407:906-8.
Conference:
Biomag 2010 - 17th International Conference on Biomagnetism , Dubrovnik, Croatia, 28 Mar - 1 Apr, 2010.
Presentation Type:
Poster Presentation
Topic:
Sensory Processing and Functional Connectivity
Citation:
Franciotti
R,
Brancucci
A,
Penna
SD,
Pizzella
V,
Romani
GL and
Tommasi
L
(2010). Crossmodal Audio-Visual Integration In The Human Auditory and Visual Cortices Revealed By Magnetoencephalography..
Front. Neurosci.
Conference Abstract:
Biomag 2010 - 17th International Conference on Biomagnetism .
doi: 10.3389/conf.fnins.2010.06.00198
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Received:
29 Mar 2010;
Published Online:
29 Mar 2010.
*
Correspondence:
Raffaella Franciotti, 'G. D'Annunzio' University, ITAB and Department of Clinical Sciences and Bioimaging, Chieti, Italy, raffaella.franciotti@itab.unich.it