The right posterior inferior frontal gyrus contributes to phonological word decisions in the healthy brain: Evidence from dual-site TMS

Gesa Hartwigsen*, Cathy J. Price, Annette Baumgaertner, Gesine Geiss, Maria Koehnke, Stephan Ulmer, Hartwig R. Siebner

*Corresponding author for this work
95 Citations (Scopus)

Abstract

There is consensus that the left hemisphere plays a dominant role in language processing, but functional imaging studies have shown that the right as well as the left posterior inferior frontal gyri (pIFG) are activated when healthy right-handed individuals make phonological word decisions. Here we used online transcranial magnetic stimulation (TMS) to examine the functional relevance of the right pIFG for auditory and visual phonological decisions. Healthy right-handed individuals made phonological or semantic word judgements on the same set of auditorily and visually presented words while they received stereotactically guided TMS over the left, right or bilateral pIFG (n=14) or the anterior left, right or bilateral IFG (n=14). TMS started 100. ms after word onset and consisted of four stimuli given at a rate of 10. Hz and intensity of 90% of active motor threshold. Compared to TMS of aIFG, TMS of pIFG impaired reaction times and accuracy of phonological but not semantic decisions for visually and auditorily presented words. TMS over left, right or bilateral pIFG disrupted phonological processing to a similar degree. In a follow-up experiment, the intensity threshold for delaying phonological judgements was identical for unilateral TMS of left and right pIFG. These findings indicate that an intact function of right pIFG is necessary for accurate and efficient phonological decisions in the healthy brain with no evidence that the left and right pIFG can compensate for one another during online TMS. Our findings motivate detailed studies of phonological processing in patients with acute and chronic damage of the right pIFG.

Original languageEnglish
JournalNeuropsychologia
Volume48
Issue number10
Pages (from-to)3155-3163
Number of pages9
ISSN0028-3932
DOIs
Publication statusPublished - 08.2010

Research Areas and Centers

  • Health Sciences

DFG Research Classification Scheme

  • 206-07 Clinical Neurology Neurosurgery and Neuroradiology
  • 206-08 Cognitive and Systemic Human Neuroscience
  • 206-05 Experimental Models for Investigating Diseases of the Nervous System

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