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

TY - JOUR

T1 - The right posterior inferior frontal gyrus contributes to phonological word decisions in the healthy brain

T2 - evidence from dual-site TMS

AU - Hartwigsen, Gesa

AU - Price, Cathy J

AU - Baumgaertner, Annette

AU - Geiss, Gesine

AU - Koehnke, Maria

AU - Ulmer, Stephan

AU - Siebner, Hartwig R

N1 - Copyright (c) 2010 Elsevier Ltd. All rights reserved.

PY - 2010/8/1

Y1 - 2010/8/1

N2 - 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.

AB - 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.

KW - Acoustic Stimulation

KW - Adult

KW - Analysis of Variance

KW - Brain Mapping

KW - Decision Making

KW - Electric Stimulation

KW - Female

KW - Follow-Up Studies

KW - Frontal Lobe

KW - Functional Laterality

KW - Humans

KW - Image Processing, Computer-Assisted

KW - Magnetic Resonance Imaging

KW - Male

KW - Neuropsychological Tests

KW - Oxygen

KW - Phonetics

KW - Photic Stimulation

KW - Reaction Time

KW - Transcranial Magnetic Stimulation

KW - Vocabulary

KW - Young Adult

U2 - 10.1016/j.neuropsychologia.2010.06.032

DO - 10.1016/j.neuropsychologia.2010.06.032

M3 - Journal article

C2 - 20600177

SN - 0028-3932

VL - 48

SP - 3155

EP - 3163

JO - Neuropsychologia

JF - Neuropsychologia

IS - 10

ER -