Cerebral Cortex Advance Access originally published online on September 12, 2006
Cerebral Cortex 2007 17(7):1672-1679; doi:10.1093/cercor/bhl077
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Multisensory Interactions within Human Primary Cortices Revealed by BOLD Dynamics
1 Service de Radiodiagnostic et Radiologie Interventionnelle, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland, 2 Institut de Traitement des Signaux, Ecole Polytechnique Fédérale, Lausanne, Switzerland, 3 Division Autonome de Neuropsychologie, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland, 4 Functional Brain Mapping Laboratory, Department of Neurology, University Hospital, Geneva, Switzerland
Address correspondence to: Roberto Martuzzi, Radiology Service, CHUV, rue du Bugnon 46, 1011 Lausanne, Switzerland. Email: roberto.martuzzi{at}chuv.ch or to Micah M. Murray, The Functional Electrical Neuroimaging Laboratory, Neuropsychology Division, CHUV, Hôpital Nestlé, 5 Av. Pierre Decker, 1011 Lausanne Switzerland. Email: micah.murray{at}chuv.ch.
Whether signals from different sensory modalities converge and interact within primary cortices in humans is unresolved, despite emerging evidence in animals. This is partially because of debates concerning the appropriate analyses of functional magnetic resonance imaging (fMRI) data in response to multisensory phenomena. Using event-related fMRI, we observed that simple auditory stimuli (noise bursts) activated primary visual cortices and that simple visual stimuli (checkerboards) activated primary auditory cortices, indicative of multisensory convergence. Moreover, analyses of blood oxygen level–dependent response dynamics revealed facilitation of hemodynamic response peak latencies and slopes for multisensory auditory–visual stimuli versus either unisensory condition, indicative of multisensory interactions within primary sensory cortices. Neural processing at the lowest cortical levels can be modulated by interactions between the senses. Temporal information in fMRI data can reveal these modulations and overcome analytic and interpretational challenges of more traditional procedures. In addition to providing an essential translational link with animal models, these results suggest that longstanding notions of cortical organization need to be revised to include multisensory interactions as an inherent component of functional brain organization.
Key Words: auditory • cross-modal • fMRI • multisensory integration • primary cortex • visual
The first 2 authors contributed equally to this study.
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