title: Reliability of long-interval cortical inhibition in healthy human subjects: a TMS-EEG study.
abstract: Cortical inhibition (CI) is measured by transcranial magnetic stimulation (TMS) combined with electromyography (EMG) through long-interval CI (LICI) and cortical silent period (CSP) paradigms. Recently, we illustrated that LICI can be measured from the dorsolateral prefrontal cortex (DLPFC) through combined TMS with electroencephalography (EEG). We further demonstrated that LICI had different effects on cortical oscillations in the DLPFC compared with motor cortex. The purpose of this study was to establish the validity and reliability of TMS-EEG indices of CI and to replicate our previous findings in an extended sample. The validity of TMS-EEG was examined by evaluating its relationship to standard EMG measures of LICI and the CSP in the left motor cortex in 36 and 16 subjects, respectively. Test-retest reliability was examined in 14 subjects who returned for a repeat session within 7 days of the first session. LICI was applied to the left DLPFC in 30 subjects to compare LICI in the DLPFC with that in the motor cortex. In the motor cortex, EEG measures of LICI correlated with EMG measures of LICI and CSP. All indices of LICI showed high test-retest reliability in motor cortex and DLPFC. Gamma and beta oscillations were significantly inhibited in the DLPFC but not in the motor cortex, confirming previous findings in an extended sample. These findings demonstrate that indexing LICI through TMS combined with EEG is a valid and reliable method to evaluate inhibition from motor and prefrontal regions.
authors.affiliation: Centre for Addiction and Mental Health, 7th Floor, Clarke Division, 250 College Street, Toronto, ON M5T 1R8, Canada.
authors.forename: Faranak
authors.initials: F
authors.lastname: Farzan
authors.forename: Mera S
authors.initials: MS
authors.lastname: Barr
authors.forename: Andrea J
authors.initials: AJ
authors.lastname: Levinson
authors.forename: Robert
authors.initials: R
authors.lastname: Chen
authors.forename: Willy
authors.initials: W
authors.lastname: Wong
authors.forename: Paul B
authors.initials: PB
authors.lastname: Fitzgerald
authors.forename: Zafiris J
authors.initials: ZJ
authors.lastname: Daskalakis
mesh_terms: D000328:Adult; D002540:Cerebral Cortex / Q000502:physiology; D004569:Electroencephalography / Q000592:standards*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology*; D009433:Neural Inhibition / Q000502:physiology*; D015203:Reproducibility of Results; D013997:Time Factors; D050781:Transcranial Magnetic Stimulation / Q000592:standards*; D055815:Young Adult