Thematic role assignment in the posterior parietal cortex: A TMS study

• Published in: Neuropsychologia Vol. 77; pp. 223 - 232
• Main Authors: Finocchiaro, Chiara, Capasso, Rita, Cattaneo, Luigi, Zuanazzi, Arianna, Miceli, Gabriele
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.10.2015
• Subjects: Adult; Brain mapping; Female; Humans; Language; Language Tests; Magnetic Resonance Imaging; Male; Natural language processing; Neuropsychological Tests; Parietal Lobe - physiology; Photic Stimulation; Posterior parietal lobe; Reaction Time; Reanalysis; Thematic role assignment; Transcranial magnetic stimulation; Transcranial Magnetic Stimulation - methods; Visual Perception - physiology; Young Adult; Reanalysis; Natural language processing; Transcranial magnetic stimulation; Thematic role assignment; Posterior parietal lobe; Brain mapping
• ISSN: 0028-3932; 1873-3514
• DOI: 10.1016/j.neuropsychologia.2015.08.025

Verbs denote relations between entities acting a role in an event. Thematic roles are essential to the correct use of verbs and involve both semantic and syntactic aspects. We used repetitive Transcranial Magnetic Stimulation (rTMS) to study the involvement of three different left parietal sites in the understanding of thematic roles. In a sentence-to-picture matching task, twelve participants were asked to judge whether or not a given picture matched with a written sentence. Pictures represented simple reversible actions, and sentences were in the active or passive diathesis. Whereas both active and passive sentences require the correct encoding of thematic roles, passives also imply thematic reanalysis, as the canonical order of thematic roles is systematically reversed. The experiment was divided in three sessions. In each session a different parietal site (anterior, middle, posterior) was stimulated at 5Hz in an event-related fashion, time-locked to the presentation of visual stimuli. Results showed increased accuracy for passive sentences following posterior parietal stimulation. The effect appeared to be (a) TMS-related, as no effect was observed in a control, no-TMS experiment with eighteen new participants; (b) independent from semantic processes involved in word-picture association, as no TMS-related effects were observed in a picture-word matching task. We interpret the results as showing that the posterior parietal site is specifically involved in the assignment of thematic roles, in particular when the correct interpretation of a sentence requires reanalysis of temporarily encoded thematic roles, as in passive reversible sentences. [Display omitted] •In passive sentences, comprehension of thematic roles involves thematic reanalysis.•We applied 5Hz rTMS to three different parietal sites.•We used a sentence-picture matching task with active or passive sentences.•Accuracy increased for passives after stimulation of the posterior parietal site.•The posterior parietal site is involved in the process of thematic reanalysis.