Transcranial magnetic stimulation and peristimulus frequencygram
Clinical Neurophysiology, vol.123, no.5, pp.1002-1009, 2012 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: 123 Issue: 5
- Publication Date: 2012
- Doi Number: 10.1016/j.clinph.2011.09.019
- Journal Name: Clinical Neurophysiology
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
- Page Numbers: pp.1002-1009
- Keywords: Transcranial magnetic stimulation, Motor cortex, Human, Single motor unit
- Istanbul Gelisim University Affiliated: No
Abstract
Objective: The aim of our study was to use peristimulus frequencygram (PSF) constructed from single motor unit recordings to further characterise the responses evoked by low intensity TMS. Methods: Twelve healthy subjects (age 32 ± 11 years) received single-pulse TMS over the first dorsal interosseus (FDI) motor area during weak isometric index finger abduction. Several hundred stimuli were delivered at a frequency of ∼0.3. Hz and at an intensity of 79-110% of active motor threshold. FDI electromyogram (EMG) was recorded with surface and intramuscular fine wire electrodes. For single motor units, data analysis involved construction of a peristimulus time histogram (PSTH) and PSF. Surface EMG analysis involved signal averaging. Cumulative sums (CUSUMs) were calculated for SEMG, PSTH, and PSF data. Results: Forty-five single motor units were identified. The average number of stimuli per unit was 201 ± 112. Characterisation of the response evoked by TMS differed with the use of SEMG, PSTH, and PSF CUSUMs. Conclusions: The duration of the EMG silence that follows the MEP during voluntary contraction was longer in the PSF than SEMG and PSTH. Significance: These findings highlight the importance of using both probability and frequency-based analysis when determining the duration of inhibitory events in peripheral recordings. © 2011 International Federation of Clinical Neurophysiology.