| The effects of transcranial magnetic stimulation over the dorsolateral prefrontal cortex on suppression of habitual counting during random number generation. | |
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MedLine Citation:
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PMID: 9712014 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Random number generation is an attention-demanding task that engages working memory and executive processes. Random number generation requires holding information 'on line', suppression of habitual counting, internally driven response generation and monitoring of responses. Evidence from PET studies suggests that the dorsolateral prefrontal cortex (DLPFC) is involved in the generation of random responses. We examined the effects of short trains of transcranial magnetic stimulation (TMS) over the left or right DLPFC or medial frontal cortex on random number generation in healthy normal participants. As in previous evidence, in control trials without stimulation participants performed poorly on the random number generation task, showing repetition avoidance and a tendency to count. Brief disruption of processing with TMS over the left DLPFC changed the balance of the individuals' counting bias, increasing the most habitual counting in ones and reducing the lower probability response of counting in twos. This differential effect of TMS over the left DLPFC on the balance of the subject's counting bias was not obtained with TMS over the right DLPFC or the medial frontal cortex. The results suggest that, with disruption of the left DLPFC with TMS, habitual counting in ones that has previously been suppressed is released from inhibition. From these findings a network modulation model of random number generation is proposed, whereby suppression of habitual responses is achieved through the modulatory influence of the left DLPFC over a number-associative network in the superior temporal cortex. To allow emergence of appropriate random responses, the left DLPFC inhibits the superior temporal cortex to prevent spreading activation and habitual counting in ones. |
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Authors:
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M Jahanshahi; P Profice; R G Brown; M C Ridding; G Dirnberger; J C Rothwell |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Brain : a journal of neurology Volume: 121 ( Pt 8) ISSN: 0006-8950 ISO Abbreviation: Brain Publication Date: 1998 Aug |
Date Detail:
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Created Date: 1998-09-11 Completed Date: 1998-09-11 Revised Date: 2009-09-29 |
Medline Journal Info:
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Nlm Unique ID: 0372537 Medline TA: Brain Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 1533-44 Citation Subset: AIM; IM |
Affiliation:
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Department of Clinical Neurology, Institute of Neurology, The National Hospital for Neurology and Neurosurgery, London, UK. m.jahanshahi@ion.ucl.ac.uk |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Female Habits* Humans Male Mathematics* Models, Neurological Neuropsychological Tests Physical Stimulation Prefrontal Cortex / physiology* Random Allocation Reference Values Transcranial Magnetic Stimulation* |
| Grant Support | |
ID/Acronym/Agency:
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//Wellcome Trust |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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