Fronto-temporal interactions are functionally relevant for semantic control in language processing

PLoS One. 2017 May 15;12(5):e0177753. doi: 10.1371/journal.pone.0177753. eCollection 2017.

Abstract

Semantic cognition, i.e. processing of meaning is based on semantic representations and their controlled retrieval. Semantic control has been shown to be implemented in a network that consists of left inferior frontal (IFG), and anterior and posterior middle temporal gyri (a/pMTG). We aimed to disrupt semantic control processes with continuous theta burst stimulation (cTBS) over left IFG and pMTG and to study whether behavioral effects are moderated by induced alterations in resting-state functional connectivity. To this end, we applied real cTBS over left IFG and left pMTG as well as sham stimulation on 20 healthy participants in a within-subject design. Stimulation was followed by resting-state functional magnetic resonance imaging and a semantic priming paradigm. Resting-state functional connectivity of regions of interest in left IFG, pMTG and aMTG revealed highly interconnected left-lateralized fronto-temporal networks representing the semantic system. We did not find any significant direct modulation of either task performance or resting-state functional connectivity by effective cTBS. However, after sham cTBS, functional connectivity between IFG and pMTG correlated with task performance under high semantic control demands in the semantic priming paradigm. These findings provide evidence for the functional relevance of interactions between IFG and pMTG for semantic control processes. This interaction was functionally less relevant after cTBS over aIFG which might be interpretable in terms of an indirect disruptive effect of cTBS.

MeSH terms

  • Adult
  • Brain Mapping
  • Connectome*
  • Female
  • Frontal Lobe / physiology*
  • Humans
  • Language*
  • Magnetic Resonance Imaging
  • Male
  • Reaction Time
  • Semantics*
  • Temporal Lobe / physiology*
  • Transcranial Magnetic Stimulation
  • Young Adult

Grants and funding

Dorothee Saur was supported by the James S. McDonnell Foundation, Scholar Award Human Cognition (220020292, https://www.jsmf.org/grants/20112027/). Max Wawrzyniak was supported by a scholarship ("Promotionsförderung") of the Medical Faculty of the University of Leipzig. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.