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Updated: Jul 6, 2026
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Combined Transcranial Magnetic Stimulation and Electroencephalography of the Dorsolateral Prefrontal Cortex
Published on: August 17, 2018
Long-interval cortical inhibition from the dorsolateral prefrontal cortex: a TMS-EEG study
Zafiris J Daskalakis1, Faranak Farzan, Mera S Barr
1Schizophrenia Program, Department of Psychiatry, Centre for Addiction and Mental Health, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.
Summary
Cortical inhibition (CI) can now be measured in the motor cortex and dorsolateral prefrontal cortex (DLPFC) using transcranial magnetic stimulation (TMS) with electroencephalography (EEG). This breakthrough allows for new research into neurological and psychiatric disorders.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Psychiatry
Background:
- Cortical inhibition (CI) is measurable via paired transcranial magnetic stimulation (TMS) and surface electromyography (EMG) in the motor cortex.
- Measuring CI in regions like the dorsolateral prefrontal cortex (DLPFC) has been a significant challenge.
- The DLPFC is implicated in the pathophysiology of neurological and psychiatric disorders such as schizophrenia.
Purpose of the Study:
- To investigate the feasibility of measuring CI directly from the motor cortex and DLPFC.
- To combine TMS with electroencephalography (EEG) for CI assessment.
- To utilize the long-interval CI (LICI) paradigm for this investigation.
Main Methods:
- Paired transcranial magnetic stimulation (TMS) was applied to the motor cortex and dorsolateral prefrontal cortex (DLPFC).
- Electroencephalography (EEG) was used to record cortical evoked activity.
- Long-interval CI (LICI) was employed as the TMS paradigm to index CI.
- Simultaneously, surface electromyography (EMG) was used for motor cortex CI recording.
Main Results:
- LICI significantly suppressed cortical evoked activity in the motor cortex (32.8+/-30.5%) as measured by EEG.
- Motor cortex LICI measured by EEG strongly correlated with LICI recorded by EMG.
- LICI also significantly suppressed cortical evoked activity in the DLPFC (30.1+/-26.9%) and correlated with motor cortex LICI.
Conclusions:
- Cortical inhibition (CI) can be reliably recorded from both the motor cortex and DLPFC by combining TMS with EEG.
- This novel approach provides a method to assess CI in brain regions relevant to various disorders.
- The findings pave the way for future research into the role of CI in the pathophysiology of neurological and psychiatric conditions.
