Cerebral Cortex Advance Access published online on November 17, 2008
Cerebral Cortex, doi:10.1093/cercor/bhn200
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Cortical Plasticity of Audio–Visual Object Representations
1 Institute of Medical Psychology, Goethe-University, D-60528 Frankfurt am Main, Germany, 2 Brain Imaging Center, Goethe-University, D-60528 Frankfurt am Main, Germany, 3 Cognitive Neurology Unit, Goethe-University, D-60528 Frankfurt am Main, Germany, 4 Department of Neurophysiology, Max Planck Institute for Brain Research, D-60528 Frankfurt am Main, Germany, 5 Department of Psychology, University of Glasgow, G12 8QQ Glasgow, UK, 6 Helen Wills Neuroscience Institute, University of California - Berkeley, CA 94720, USA
Address correspondence to Marcus J. Naumer, PhD, Institut für Medizinische Psychologie, Goethe-Universität, Heinrich-Hoffmann-Strasse 10, D-60528 Frankfurt am Main, Germany. Email: M.J.Naumer{at}med.uni-frankfurt.de.
Several regions in human temporal and frontal cortex are known to integrate visual and auditory object features. The processing of audio–visual (AV) associations in these regions has been found to be modulated by object familiarity. The aim of the present study was to explore training-induced plasticity in human cortical AV integration. We used functional magnetic resonance imaging to analyze the neural correlates of AV integration for unfamiliar artificial object sounds and images in naïve subjects (PRE training) and after a behavioral training session in which subjects acquired associations between some of these sounds and images (POST-training). In the PRE-training session, unfamiliar artificial object sounds and images were mainly integrated in right inferior frontal cortex (IFC). The POST-training results showed extended integration-related IFC activations bilaterally, and a recruitment of additional regions in bilateral superior temporal gyrus/sulcus and intraparietal sulcus. Furthermore, training-induced differential response patterns to mismatching compared with matching (i.e., associated) artificial AV stimuli were most pronounced in left IFC. These effects were accompanied by complementary training-induced congruency effects in right posterior middle temporal gyrus and fusiform gyrus. Together, these findings demonstrate that short-term cross-modal association learning was sufficient to induce plastic changes of both AV integration of object stimuli and mechanisms of AV congruency processing.
Key Words: congruency • cortex • cross-modal • functional magnetic resonance imaging • human • multisensory • object perception
Marcus J. Naumer, Oliver Doehrmann, and Grit Hein contributed equally to this work.