title: Dissociating Parieto-Frontal Networks for Phonological and Semantic Word Decisions: A Condition-and-Perturb TMS Study.
abstract: Left posterior inferior frontal gyrus (pIFG) and supramarginal gyrus (SMG) are key regions for phonological decisions, whereas angular gyrus (ANG) and anterior IFG (aIFG) are associated with semantics. However, it is less clear whether the functional contribution of one area changes in the presence of a dysfunctional area within the network. Using repetitive transcranial magnetic stimulation (rTMS), we first tested whether perturbing one area would disrupt behavior. Second, we applied a condition-and-perturb approach, combining parietal offline rTMS with frontal online rTMS to investigate how the functional contribution of a frontal region changes in the presence of a dysfunctional parietal region. We found that rTMS over SMG or pIFG delayed phonological decisions, but this was not enhanced by combining supramarginal rTMS with pIFG rTMS. In contrast, semantic decisions were only impaired when angular rTMS was combined with aIFG rTMS. We infer that offline rTMS caused a dysfunction of ANG which increased the functional relevance of aIFG for semantic decisions and sensitized this network to the disruptive effects of aIFG rTMS. The results provide causal evidence that ANG and aIFG contribute to semantics and that the functional significance of one area within this network depends on the functional integrity of the other.
authors.affiliation: Language and Aphasia Laboratory, Department of Neurology, University of Leipzig, D-04103 Leipzig, Germany.|Max Planck Institute for Human Cognitive and Brain Sciences, D-04103 Leipzig, Germany.|Department of Psychology, Christian-Albrechts-University, D-24118 Kiel, Germany.
authors.forename: Gesa
authors.initials: G
authors.lastname: Hartwigsen
authors.affiliation: Language and Aphasia Laboratory, Department of Neurology, University of Leipzig, D-04103 Leipzig, Germany.
authors.forename: Anni
authors.initials: A
authors.lastname: Weigel
authors.affiliation: Language and Aphasia Laboratory, Department of Neurology, University of Leipzig, D-04103 Leipzig, Germany.
authors.forename: Paul
authors.initials: P
authors.lastname: Schuschan
authors.affiliation: Danish Research Centre for Magnetic Resonance, Copenhagen University Hospital Hvidovre, 2650 Hvidovre, Denmark.
authors.forename: Hartwig R
authors.initials: HR
authors.lastname: Siebner
authors.affiliation: Human Cortical Physiology and Motor Control Laboratory, Department of Neurology, University of Leipzig, D-04103 Leipzig, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Weise
authors.affiliation: Human Cortical Physiology and Motor Control Laboratory, Department of Neurology, University of Leipzig, D-04103 Leipzig, Germany.
authors.forename: Joseph
authors.initials: J
authors.lastname: Classen
authors.affiliation: Language and Aphasia Laboratory, Department of Neurology, University of Leipzig, D-04103 Leipzig, Germany.|Max Planck Institute for Human Cognitive and Brain Sciences, D-04103 Leipzig, Germany.
authors.forename: Dorothee
authors.initials: D
authors.lastname: Saur
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D003657:Decision Making / Q000502:physiology*; D005260:Female; D005625:Frontal Lobe / Q000502:physiology*; D006801:Humans; D007807:Language Tests; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D009483:Neuropsychological Tests; D010296:Parietal Lobe / Q000502:physiology*; D010700:Phonetics; D011930:Reaction Time; D012660:Semantics; D013067:Speech Perception / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods; D055815:Young Adult
keywords: inferior frontal gyrus; language; parietal cortex; transcranial magnetic stimulation; virtual lesion