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The Journal of Neuroscience, December 13, 2006, 26(50):13025-13036; doi:10.1523/JNEUROSCI.2481-06.2006
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Behavioral/Systems/Cognitive
Discrimination Training Alters Object Representations in Human Extrastriate Cortex
Hans P. Op de Beeck,1 Chris I. Baker,1 James J. DiCarlo,1 andNancy G. Kanwisher1,2 1McGovern Institute for Brain Research and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and 2Martinos Center for Biomedical Imaging, Charlestown, Massachusetts 02129
Correspondence should be addressed to Hans P. Op de Beeck, Laboratory of Experimental Psychology, University of Leuven, Tiesentraat 102, 3000 Leuven, Belgium. Email: hans.opdebeeck{at}psy.kuleuven.be
Visual object recognition relies critically on learning. However, little is known about the effect of object learning in human visual cortex, and in particular how the spatial distribution of training effects relates to the distribution of object and face selectivity across the cortex before training. We scanned human subjects with high-resolution functional magnetic resonance imaging (fMRI) while they viewed novel object classes, both before and after extensive training to discriminate between exemplars within one of these object classes. Training increased the strength of the response in visual cortex to trained objects compared with untrained objects. However, training did not simply induce a uniform increase in the response to trained objects: the magnitude of this training effect varied substantially across subregions of extrastriate cortex, with some showing a twofold increase in response to trained objects and others (including the right fusiform face area) showing no significant effect of training. Furthermore, the spatial distribution of training effects could not be predicted from the spatial distribution of either pretrained responses or face selectivity. Instead, training changed the spatial distribution of activity across the cortex. These findings support a dynamic view of the ventral visual pathway in which the cortical representation of an object category is continuously modulated by experience.
Key words: recognition; perception; visual; fMRI; occipital; fusiform
Received Feb. 27, 2006; revised Oct. 30, 2006; accepted Nov. 4, 2006.
Correspondence should be addressed to Hans P. Op de Beeck, Laboratory of Experimental Psychology, University of Leuven, Tiesentraat 102, 3000 Leuven, Belgium. Email: hans.opdebeeck{at}psy.kuleuven.be
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