title: Side effects of transcranial magnetic stimulation biased task performance in a cognitive neuroscience study.
abstract: Transcranial magnetic stimulation (TMS) is increasingly used as a research tool for functional brain mapping in cognitive neuroscience. Despite being mostly tolerable, side effects of TMS could influence task performance in behavioural TMS studies. In order to test this issue, healthy subjects assessed the discomfort caused by the stimulation during a verbal working memory task. We investigated the relation between subjective disturbance and task performance. Subjects were stimulated during the delay period of a delayed-match-to-sample task above cortical areas that had been identified before to be involved in working memory. Task performance and subjective disturbance due to side effects were monitored. The subjects' grade of discomfort correlated with the error rates: the higher the discomfort, the more errors were made. Conclusively, TMS side effects may bias task performance in cognitive neuroscience studies and may thereby lead to misinterpretation of results. We emphasize the importance of controlling side effects of the stimulation as a source of biasing effects in TMS studies.
authors.affiliation: Department of Psychiatry, University of Ulm, Germany. birgit.abler@medizin.uni-ulm.de
authors.forename: Birgit
authors.initials: B
authors.lastname: Abler
authors.forename: Henrik
authors.initials: H
authors.lastname: Walter
authors.forename: Arthur
authors.initials: A
authors.lastname: Wunderlich
authors.forename: Jo
authors.initials: J
authors.lastname: Grothe
authors.forename: Carlos
authors.initials: C
authors.lastname: Schönfeldt-Lecuona
authors.forename: Manfred
authors.initials: M
authors.lastname: Spitzer
authors.forename: Uwe
authors.initials: U
authors.lastname: Herwig
mesh_terms: D000328:Adult; D016477:Artifacts; D001931:Brain Mapping / Q000295:instrumentation*; D002540:Cerebral Cortex / Q000503:physiopathology / Q000528:radiation effects*; D004558:Electric Stimulation / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008569:Memory Disorders / Q000209:etiology / Q000503:physiopathology / Q000523:psychology; D008570:Memory, Short-Term / Q000502:physiology / Q000528:radiation effects*; D009483:Neuropsychological Tests; D009488:Neurosciences / Q000295:instrumentation / Q000379:methods; D010296:Parietal Lobe / Q000503:physiopathology / Q000528:radiation effects; D017397:Prefrontal Cortex / Q000503:physiopathology / Q000528:radiation effects; D011597:Psychomotor Performance / Q000502:physiology / Q000528:radiation effects; D050781:Transcranial Magnetic Stimulation / Q000009:adverse effects*; D014705:Verbal Behavior / Q000502:physiology / Q000528:radiation effects*