The inferior frontal cortex in artificial syntax processing: an rTMS study.
The human capacity to implicitly acquire knowledge of structured sequences has recently been investigated in artificial grammar learning using functional magnetic resonance imaging. It was found that the left inferior frontal cortex (IFC; Brodmann's area (BA) 44/45) was related to classification performance. The objective of this study was to investigate whether the IFC (BA 44/45) is causally related to classification of artificial syntactic structures by means of an off-line repetitive transcranial magnetic stimulation (rTMS) paradigm. We manipulated the stimulus material in a 2 x 2 factorial design with grammaticality status and local substring familiarity as factors. The participants showed a reliable effect of grammaticality on classification of novel items after 5 days of exposure to grammatical exemplars without performance feedback in an implicit acquisition task. The results show that rTMS of BA 44/45 improves syntactic classification performance by increasing the rejection rate of non-grammatical items and by shortening reaction times of correct rejections specifically after left-sided stimulation. A similar pattern of results is observed in FMRI experiments on artificial syntactic classification. These results suggest that activity in the inferior frontal region is causally related to artificial syntax processing.
Uddén
Julia
J
Max Planck Institute for Psycholinguistics, P.O. Box 310, NL-6500 AH Nijmegen, The Netherlands.
Folia
Vasiliki
V
Forkstam
Christian
C
Ingvar
Martin
M
Fernandez
Guillen
G
Overeem
Sebastiaan
S
van Elswijk
Gijs
G
Hagoort
Peter
P
Petersson
Karl Magnus
KM
D000328:Adult; D001931:Brain Mapping; D003071:Cognition / Q000502:physiology; D004292:Dominance, Cerebral / Q000502:physiology; D005260:Female; D005625:Frontal Lobe / Q000033:anatomy & histology / Q000502:physiology*; D006801:Humans; D007802:Language; D007807:Language Tests; D007858:Learning / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D011932:Reading; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation; D014705:Verbal Behavior / Q000502:physiology*