Cerebral Cortex Advance Access published online on March 19, 2007
Cerebral Cortex, doi:10.1093/cercor/bhm018
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The Effect of Visual Experience on the Development of Functional Architecture in hMT+
1 Laboratory of Clinical Biochemistry and Molecular Biology, Department of Experimental Pathology, Medical Biotechnologies, Infectivology, and Epidemiology, University of Pisa Medical School, I-56126 Pisa, Italy, 2 Magnetic Resonance Imaging Laboratory, Institute of Clinical Physiology, National Council of Research, Research Area, I-56126 Pisa, Italy, 3 Interdepartmental Research Center "E. Piaggio," University of Pisa, I-56126 Pisa, Italy, 4 Psychology Branch, Department of Psychiatry, Neurobiology, Pharmacology, and Biotechnologies, University of Pisa Medical School, I-56126 Pisa, Italy, 5 Department of Psychology, Princeton University, Princeton, NJ 08544, USA
Address correspondence to Pietro Pietrini, Laboratory of Clinical Biochemistry and Molecular Biology, University of Pisa Medical School, Via Roma, 67 I-56126 Pisa, Italy. Email: pietro.pietrini{at}med.unipi.it.
We investigated whether the visual hMT+ cortex plays a role in supramodal representation of sensory flow, not mediated by visual mental imagery. We used functional magnetic resonance imaging to measure neural activity in sighted and congenitally blind individuals during passive perception of optic and tactile flows. Visual motion–responsive cortex, including hMT+, was identified in the lateral occipital and inferior temporal cortices of the sighted subjects by response to optic flow. Tactile flow perception in sighted subjects activated the more anterior part of these cortical regions but deactivated the more posterior part. By contrast, perception of tactile flow in blind subjects activated the full extent, including the more posterior part. These results demonstrate that activation of hMT+ and surrounding cortex by tactile flow is not mediated by visual mental imagery and that the functional organization of hMT+ can develop to subserve tactile flow perception in the absence of any visual experience. Moreover, visual experience leads to a segregation of the motion-responsive occipitotemporal cortex into an anterior subregion involved in the representation of both optic and tactile flows and a posterior subregion that processes optic flow only.
Key Words: blind subjects • functional magnetic resonance imaging (fMRI) • hMT+ • optic flow • supramodality • tactile flow
Funding to pay the Open Access publication charges for this article was provided by Fondazione IRIS, Castagneto Carducci (Livorno, Italy).
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