Cerebral Cortex Advance Access published online on November 11, 2009
Cerebral Cortex, doi:10.1093/cercor/bhp230
Perceptual and Semantic Contributions to Repetition Priming of Environmental Sounds
1 Electroencephalography Brain Mapping Core, Center for Biomedical Imaging, Centre Hospitalier Universitaire Vaudois and University of Lausanne, 1011 Lausanne, Switzerland, 2 Institute of Psychology, University of Lausanne, 1005 Lausanne, Switzerland, 3 Melbourne Neuropsychiatry Centre, University of Melbourne, 3053 Melbourne, Australia, 4 Radiology Service, 5 Neuropsychology and Neurorehabilitation Service, Centre Hospitalier Universitaire Vaudois and University of Lausanne, 1011 Lausanne, Switzerland
Address correspondence to Marzia De Lucia, Radiology-CHUV, BH 07 081 1, Rue Bugnon 46, 1011 Lausanne, Switzerland. Email: marzia.de-lucia{at}hospvd.ch.
Repetition of environmental sounds, like their visual counterparts, can facilitate behavior and modulate neural responses, exemplifying plasticity in how auditory objects are represented or accessed. It remains controversial whether such repetition priming/suppression involves solely plasticity based on acoustic features and/or also access to semantic features. To evaluate contributions of physical and semantic features in eliciting repetition-induced plasticity, the present functional magnetic resonance imaging (fMRI) study repeated either identical or different exemplars of the initially presented object; reasoning that identical exemplars share both physical and semantic features, whereas different exemplars share only semantic features. Participants performed a living/man-made categorization task while being scanned at 3T. Repeated stimuli of both types significantly facilitated reaction times versus initial presentations, demonstrating perceptual and semantic repetition priming. There was also repetition suppression of fMRI activity within overlapping temporal, premotor, and prefrontal regions of the auditory "what" pathway. Importantly, the magnitude of suppression effects was equivalent for both physically identical and semantically related exemplars. That the degree of repetition suppression was irrespective of whether or not both perceptual and semantic information was repeated is suggestive of a degree of acoustically independent semantic analysis in how object representations are maintained and retrieved.
Key Words: auditory • fMRI • object recognition • perceptual priming • semantic priming • what and where pathways