title: Left perirhinal cortex codes for similarity in meaning between written words: Comparison with auditory word input.
abstract: Left perirhinal cortex has been previously implicated in associative coding. According to a recent experiment, the similarity of perirhinal fMRI response patterns to written concrete words is higher for words which are more similar in their meaning. If left perirhinal cortex functions as an amodal semantic hub, one would predict that this semantic similarity effect would extend to the spoken modality. We conducted an event-related fMRI experiment and evaluated whether a same semantic similarity effect could be obtained for spoken as for written words. Twenty healthy subjects performed a property verification task in either the written or the spoken modality. Words corresponded to concrete animate entities for which extensive feature generation was available from more than 1000 subjects. From these feature generation data, a concept-feature matrix was derived which formed the basis of a cosine similarity matrix between the entities reflecting their similarity in meaning (called the "semantic cossimilarity matrix"). Independently, we calculated a cosine similarity matrix between the left perirhinal fMRI activity patterns evoked by the words (called the "fMRI cossimilarity matrix"). Next, the similarity was determined between the semantic cossimilarity matrix and the fMRI cossimilarity matrix. This was done for written and spoken words pooled, for written words only, for spoken words only, as well as for crossmodal pairs. Only for written words did the fMRI cossimilarity matrix correlate with the semantic cossimilarity matrix. Contrary to our prediction, we did not find any such effect for auditory word input nor did we find cross-modal effects in perirhinal cortex between written and auditory words. Our findings situate the contribution of left perirhinal cortex to word processing at the top of the visual processing pathway, rather than at an amodal stage where visual and auditory word processing pathways have already converged.
authors: Laboratory for Cognitive Neurology, Department of Neurosciences, University of Leuven, Belgium.
authors: Antonietta Gabriella
authors: AG
authors: Liuzzi
authors: Laboratory for Cognitive Neurology, Department of Neurosciences, University of Leuven, Belgium.
authors: Rose
authors: R
authors: Bruffaerts
authors: Laboratory for Cognitive Neurology, Department of Neurosciences, University of Leuven, Belgium.
authors: Patrick
authors: P
authors: Dupont
authors: Laboratory for Cognitive Neurology, Department of Neurosciences, University of Leuven, Belgium.
authors: Katarzyna
authors: K
authors: Adamczuk
authors: Radiology Department, University Hospitals Leuven, Leuven, Belgium.
authors: Ronald
authors: R
authors: Peeters
authors: Laboratory of Experimental Psychology, Humanities and Social Sciences Group, University of Leuven, Leuven, Belgium.
authors: Simon
authors: S
authors: De Deyne
authors: Laboratory of Experimental Psychology, Humanities and Social Sciences Group, University of Leuven, Leuven, Belgium.
authors: Gerrit
authors: G
authors: Storms
authors: Laboratory for Cognitive Neurology, Department of Neurosciences, University of Leuven, Belgium; Neurology Department, University Hospitals Leuven, Herestraat 49 bus 7003, B-3000 Leuven, Belgium. Electronic address: rik.vandenberghe@uz.kuleuven.ac.be.
authors: Rik
authors: R
authors: Vandenberghe
mesh_terms: D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D006801:Humans; D008279:Magnetic Resonance Imaging; D011932:Reading; D012660:Semantics; D013067:Speech Perception / Q000502:physiology*; D013702:Temporal Lobe / Q000503:physiopathology*; D055815:Young Adult
keywords: Anterior temporal; MVPA; Orthographic; Reading; Semantic; Spoken; fMRI