title: Specific and non-specific effects of transcranial magnetic stimulation on simple and go/no-go reaction time.
abstract: The effects of subthreshold transcranial magnetic stimulation (TMS) on simple and go/no-go reaction time (RT) tasks were studied in seven healthy volunteers. Subjects were asked to respond by abducting the thumb in a warning-imperative signal paradigm. TMS was randomly delivered at variable delays to the imperative signal (IS). Simple RT was significantly shortened when TMS was delivered to the left motor cortex and parietal regions simultaneously with IS. In the go/no-go paradigm, a similar trend to shorter RT was seen at a delay of 0 ms. Additionally, a significant shortening was observed at a delay of 90 ms with TMS over the contralateral motor cortex only. Movement-related potentials (MRPs) in the two paradigms showed a predominantly contralateral negativity approximately 80 ms preceding EMG onset. Our findings support the existence of two differentiated effects of TMS on RT: (1) one non-specific effect, evidenced in both the simple and go/no-go paradigms at a 0 ms delay, which can be at least partially explained by intersensory facilitation; and (2) a motor-specific effect of TMS, unveiled in the go/no-go paradigm at a 90 ms delay.
authors.affiliation: Human Cortical Physiology Section, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD 20892-1430, USA. lumy@codon.nih.gov
authors.forename: L
authors.initials: L
authors.lastname: Sawaki
authors.forename: T
authors.initials: T
authors.lastname: Okita
authors.forename: M
authors.initials: M
authors.lastname: Fujiwara
authors.forename: K
authors.initials: K
authors.lastname: Mizuno
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology*; D004569:Electroencephalography; D004576:Electromyography; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D008959:Models, Neurological; D009043:Motor Activity; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology*; D012016:Reference Values; D013933:Thumb / Q000294:innervation / Q000502:physiology; D050781:Transcranial Magnetic Stimulation