Differentiating transcranial magnetic stimulation cortical and auditory responses via single pulse and paired pulse protocols: A TMS-EEG study. Issue 8 (August 2021)

• Record Type: Journal Article
• Authors: Poorganji, Mohsen; Zomorrodi, Reza; Hawco, Colin; Hill, Aron T.; Hadas, Itay; Rajji, Tarek K.; Chen, Robert; Voineskos, Daphne; Daskalakis, Anastasios A.; Blumberger, Daniel M.; Daskalakis, Zafiris J.
• Is Part Of: Clinical neurophysiology. Volume 132:Issue 8(2021)
• Page Start: 1850
• Page End: 1858
• Publication Date: 2021-08
• Subjects: TMS-EEG -- Sham TMS -- Long interval cortical inhibition -- TMS-evoked potential; TMS Transcranial Magnetic Stimulation -- EEG Electroencephalography -- TEP TMS Evoked Potential -- AEP Auditory Evoked Potential -- SEP Somatosensory Evoked Potential -- PEP Peripherally Evoked Potential -- SP Single Pulse -- PP Paired Pulse -- LICI long interval cortical inhibition -- CI Cortical Inhibition -- AUC Area Under the Curve -- DLPFC Dorsolateral Prefrontal Cortex -- MRI Magnetic Resonance Imaging -- MNI Montreal Neurological Institute -- APB Abductor Pollicis Brevis -- ICA Independent Component Analysis; Neurophysiology -- Periodicals; Electroencephalography -- Periodicals; Electromyography -- Periodicals; Neurology -- Periodicals; 612.8
• DOI: 10.1016/j.clinph.2021.05.009
• Languages: English
• ISSNs: 1388-2457

Abstract

Highlights: Active single-pulse TMS generates similar waveform as auditory response but with larger amplitude. Only active paired-pulse protocol induced significant cortical inhibition in dorsolateral prefrontal cortex. Cortical inhibition is observed over all frequency bands in active long interval cortical inhibition. Abstract: Objective: We measured the neurophysiological responses of both active and sham transcranial magnetic stimulation (TMS) for both single pulse (SP) and paired pulse (PP; long interval cortical inhibition (LICI)) paradigms using TMS-EEG (electroencephalography). Methods: Nineteen healthy subjects received active and sham (coil 90° tilted and touching the scalp) SP and PP TMS over the left dorsolateral prefrontal cortex (DLPFC). We measured excitability through SP TMS and inhibition (i.e., cortical inhibition (CI)) through PP TMS. Results: Cortical excitability indexed by area under the curve (AUC(25-275ms) ) was significantly higher in the active compared to sham stimulation (F(1, 18) = 43.737, p < 0.001, η 2 = 0.708). Moreover, the amplitude of N100-P200 complex was significantly larger (F(1, 18) = 9.118, p < 0.01, η 2 = 0.336) with active stimulation (10.38 ± 9.576 µV) compared to sham (4.295 ± 2.323 µV). Significant interaction effects were also observed between active and sham stimulation for both the SP and PP (i.e., LICI) cortical responses. Finally, only active stimulation (CI = 0.64 ± 0.23, p < 0.001) resulted in significant cortical inhibition. Conclusion: The significant differences between active and sham stimulation in both excitatory and inhibitory neurophysiological responses showed that active stimulation elicits responses from the cortex that are different from the non-specific effects of sham stimulation. Significance: Our study reaffirms that TMS-EEG represents an effective tool to evaluate cortical neurophysiology with high fidelity.