title: On the role of the supramarginal gyrus in phonological processing and verbal working memory: evidence from rTMS studies.
abstract: The supramarginal gyrus (SMG) is activated for phonological processing during both language and verbal working memory tasks. Using rTMS, we investigated whether the contribution of the SMG to phonological processing is domain specific (specific to phonology) or more domain general (specific to verbal working memory). A measure of phonological complexity was developed based on sonority differences and subjects were tested after low frequency rTMS on a same/different judgment task and an n-back verbal memory task. It was reasoned that if the phonological processing in the SMG is more domain general, i.e., related to verbal working memory demands, performance would be more affected by the rTMS during the n-back task than during the same/different judgment task. Two auditory experiments were conducted. The first experiment demonstrated that under conditions where working memory demands are minimized (i.e. same/different judgment), repetitive stimulation had no effect on performance although performance varied as a function of phonological complexity. The second experiment demonstrated that during a verbal working memory task (n-back task), where phonological complexity was also manipulated, subjects were less accurate and slower at performing the task after stimulation but the effect of phonology was not affected. The results confirm that the SMG is involved in verbal working memory but not in the encoding of sonority differences.
authors.affiliation: McGill University, Faculty of Medicine, School of Communication Sciences and Disorders, 1266 Avenue des Pins, Montreal, Quebec, Canada H3G 1A8; Centre for Research on Brain, Language and Music, Rabinovitch House, McGill University, 3640 rue de la Montagne, Montreal, Quebec, Canada H3G 2A8. Electronic address: isabelle.deschamps@mail.mcgill.ca.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Deschamps
authors.affiliation: McGill University, Faculty of Medicine, School of Communication Sciences and Disorders, 1266 Avenue des Pins, Montreal, Quebec, Canada H3G 1A8; Centre for Research on Brain, Language and Music, Rabinovitch House, McGill University, 3640 rue de la Montagne, Montreal, Quebec, Canada H3G 2A8.
authors.forename: Shari R
authors.initials: SR
authors.lastname: Baum
authors.affiliation: McGill University, Faculty of Medicine, School of Communication Sciences and Disorders, 1266 Avenue des Pins, Montreal, Quebec, Canada H3G 1A8; Centre for Research on Brain, Language and Music, Rabinovitch House, McGill University, 3640 rue de la Montagne, Montreal, Quebec, Canada H3G 2A8; Haskins Laboratories, 300 George St., Suite 900, New Haven, CT 06511, USA.
authors.forename: Vincent L
authors.initials: VL
authors.lastname: Gracco
mesh_terms: D000161:Acoustic Stimulation; D001307:Auditory Perception / Q000502:physiology; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007600:Judgment / Q000502:physiology; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D009483:Neuropsychological Tests; D010296:Parietal Lobe / Q000502:physiology*; D046709:Pattern Recognition, Physiological / Q000502:physiology; D010700:Phonetics; D011930:Reaction Time; D013067:Speech Perception / Q000502:physiology*; D013647:Task Performance and Analysis; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
keywords: Phonological processing; Supramarginal gyrus; Transcranial magnetic stimulation; Verbal working memory