title: A perfusion fMRI investigation of thematic and categorical context effects in the spoken production of object names.
abstract: The context in which objects are presented influences the speed at which they are named. We employed the blocked cyclic naming paradigm and perfusion functional magnetic resonance imaging (fMRI) to investigate the mechanisms responsible for interference effects reported for thematically and categorically related compared to unrelated contexts. Naming objects in categorically homogeneous contexts induced a significant interference effect that accumulated from the second cycle onwards. This interference effect was associated with significant perfusion signal decreases in left middle and posterior lateral temporal cortex and the hippocampus. By contrast, thematically homogeneous contexts facilitated naming latencies significantly in the first cycle and did not differ from heterogeneous contexts thereafter, nor were they associated with any perfusion signal changes compared to heterogeneous contexts. These results are interpreted as being consistent with an account in which the interference effect both originates and has its locus at the lexical level, with an incremental learning mechanism adapting the activation levels of target lexical representations following access. We discuss the implications of these findings for accounts that assume thematic relations can be active lexical competitors or assume mandatory involvement of top-down control mechanisms in interference effects during naming.
authors.affiliation: University of Queensland, School of Psychology, Brisbane, Australia. Electronic address: greig.dezubicaray@uq.edu.au.
authors.forename: Greig
authors.initials: G
authors.lastname: de Zubicaray
authors.affiliation: University of Queensland, School of Health and Rehabilitation Sciences, Brisbane, Australia.
authors.forename: Kori
authors.initials: K
authors.lastname: Johnson
authors.affiliation: School of Education, Communication and Language Sciences, Newcastle University, Newcastle-upon-Tyne, UK.
authors.forename: David
authors.initials: D
authors.lastname: Howard
authors.affiliation: University of Queensland, Centre for Advanced Imaging, Brisbane, Australia.
authors.forename: Katie
authors.initials: K
authors.lastname: McMahon
mesh_terms: D000293:Adolescent; D000328:Adult; D001288:Attention / Q000502:physiology; D005260:Female; D059907:Functional Neuroimaging; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009275:Names; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D011930:Reaction Time / Q000502:physiology; D013060:Speech / Q000502:physiology*; D013702:Temporal Lobe / Q000502:physiology*; D055815:Young Adult
keywords: Lexical selection; Object naming; Semantic interference; Spoken word production