Verb and sentence processing with TMS: A systematic review and meta-analysis

Transcranial magnetic stimulation (TMS) has provided relevant evidence regarding the neural correlates of language. The aim of the present study is to summarize and assess previous findings regarding linguistic levels (i.e., semantic and morpho-syntactic) and brain structures utilized during verb and sentence processing. To do that, we systemati-cally reviewed TMS research on verb and sentence processing in healthy speakers, and meta-analyzed TMS-induced effects according to the region of stimulation and experi-mental manipulation. Findings from 45 articles show that approximately half of the reviewed work focuses on the embodiment of action verbs. The majority of studies (60%) target only one cortical region in relation to a specific linguistic process. Frontal areas are most frequently stimulated in connection to morphosyntactic processes and action verb semantics, and temporoparietal regions in relation to integration of sentential meaning and thematic role assignment. A meta-analysis of 72 effect sizes of the reviewed papers indicates that TMS has a small overall effect size, but effect sizes for anterior compared to posterior regions do not differ for semantic or morphosyntactic contrasts. Our findings stress the need to increase the number of targeted areas, while using the same linguistic contrasts in order to disentangle the contributions of different cortical regions to distinct linguistic processes.& COPY; 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Automated summary

Transcranial magnetic stimulation(TMS) has been used to study the neural correlates of language, specifically verb and sentence processing. This systematic review and meta-analysis of 45 articles found that most studies focused on action verb embodiment, and frontal areas were most frequently stimulated for morphosyntactic processes and action verb semantics. Temporoparietal regions were most commonly stimulated for integration of sentential meaning and thematic role assignment. The overall effect size of TMS was small, but there was no difference in effect sizes between anterior and posterior regions for semantic or morphosyntactic contrasts.