Poster D25, Friday, August 17, 4:45 – 6:30 pm, Room 2000AB
Contributions of left frontal and temporal cortex to sentence comprehension: Evidence from simultaneous TMS-EEG.
Thomas Gunter1, Leon Kroczek1, Anna Rysop1, Angela Friederici1, Gesa Hartwigsen1;1Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
Sentence comprehension requires the rapid analysis of semantic and syntactic information. These processes are supported by a left hemispheric dominant fronto-temporal network, including left posterior inferior frontal gyrus (pIFG) and posterior superior temporal gyrus/sulcus (pSTG/STS). Previous electroencephalography (EEG) studies have associated semantic expectancy within a sentence with a modulation of the N400 and syntactic gender violations with increases in the LAN and P600. Here, we combined focal perturbations of neural activity by means of short bursts of transcranial magnetic stimulation (TMS) with simultaneous EEG recordings to probe the functional relevance of pIFG and pSTG/STS for sentence comprehension. We applied 10 Hz TMS bursts of three pulses at verb onset during auditory presentation of short sentences (i.e. pronoun-verb-article-noun). Semantic expectancy and syntactic gender was manipulated at the sentence final noun. TMS had a short-lasting impact restricted to the mid-sentence verb and affected verb processing differently for the two stimulation sites. Specifically, TMS over pIFG elicited a frontal positivity in the first 200 ms and a more parietal negativity at 400-600 ms post verb onset. TMS over pSTG/STS was limited to a parietal negativity at 100-700 ms post verb onset. This suggests that during verb processing in sentential context, frontal brain areas play an earlier role than temporal areas in predicting the upcoming noun pointing to a possible top-down control of pIFG on pSTG/STS. The short-living perturbation effect further suggests a high degree of flexible compensation for focal perturbation in the language system because the sentence final noun processing was unaffected.
Topic Area: Grammar: Morphology