title: Stimulus-driven changes in the direction of neural priming during visual word recognition.
abstract: Visual object recognition is generally known to be facilitated when targets are preceded by the same or relevant stimuli. For written words, however, the beneficial effect of priming can be reversed when primes and targets share initial syllables (e.g., "boca" and "bono"). Using fMRI, the present study explored neuroanatomical correlates of this negative syllabic priming. In each trial, participants made semantic judgment about a centrally presented target, which was preceded by a masked prime flashed either to the left or right visual field. We observed that the inhibitory priming during reading was associated with a left-lateralized effect of repetition enhancement in the inferior frontal gyrus (IFG), rather than repetition suppression in the ventral visual region previously associated with facilitatory behavioral priming. We further performed a second fMRI experiment using a classical whole-word repetition priming paradigm with the same hemifield procedure and task instruction, and obtained well-known effects of repetition suppression in the left occipito-temporal cortex. These results therefore suggest that the left IFG constitutes a fast word processing system distinct from the posterior visual word-form system and that the directions of repetition effects can change with intrinsic properties of stimuli even when participants' cognitive and attentional states are kept constant.
authors.affiliation: Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan.
authors.forename: Maciej
authors.initials: M
authors.lastname: Pas
authors.affiliation: Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan. Electronic address: nakamura.kimihiro.4w@kyoto-u.ac.jp.
authors.forename: Kimihiro
authors.initials: K
authors.lastname: Nakamura
authors.affiliation: Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan.
authors.forename: Nobukatsu
authors.initials: N
authors.lastname: Sawamoto
authors.affiliation: Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Aso
authors.affiliation: Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto 606-8507, Japan.
authors.forename: Hidenao
authors.initials: H
authors.lastname: Fukuyama
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology*; D017397:Prefrontal Cortex / Q000502:physiology*; D011932:Reading; D060865:Repetition Priming / Q000502:physiology*; D012660:Semantics; D055815:Young Adult
keywords: Functional magnetic resonance imaging; Inferior frontal gyrus; Masked inhibitory priming; Repetition enhancement and suppression; Visual word recognition