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How TMS-EEG is Reshaping Clinical Research

Understanding how drugs interact with the brain, at a systems level, is essential for developing more targeted and effective treatments. A recent study, by Rocchi et al. (2025) highlights a powerful and non-invasive way to probe these effects: transcranial magnetic stimulation (TMS) with variable pulse widths, used to measure strength–duration time constants (SDTCs), a biomarker of sodium channel dynamics. This approach, typically used in peripheral nerves, has now been extended to the motor cortex, offering new insights into how medications like carbamazepine and lacosamide modulate cortical excitability in humans.

 

Why does this matter for clinical trials?

Traditional endpoints, like behavioural responses or clinical symptom scales, often don’t capture the underlying neurophysiological changes that occur early in treatment. However, SDTC and rheobase offer objective, quantifiable readouts of how a compound interacts with specific ion channels in the brain. In this case, researchers confirmed that sodium channel blockers increased motor thresholds and altered excitability in predictable ways, demonstrating that SDTC can serve as a reliable pharmacodynamic marker.

 

At The Science Behind, we specialise in deploying advanced TMS and EEG techniques to help sponsors, CROs, and research teams integrate these types of functional readouts into their early-phase and proof-of-concept studies. Whether you're evaluating CNS-active compounds, neuromodulation interventions, or need translational endpoints, our team brings deep experience in:

  • TMS protocol design and dose-finding for cortical excitability studies
  • Multimodal integration, including EEG, EMG, and QST
  • On-site and remote support for clinical sites data collection
  • Statistical and pharmacodynamic analysis aligned with regulatory expectations

 

Rocchi et al. (2025)’s recent study underscores how TMS can differentiate subtle, mechanistically relevant effects, even between drugs targeting the same channel family. These insights are invaluable not just for demonstrating proof of mechanism, but for derisking your pipeline earlier in development.

 

Rocchi, L., Brown, K., Di Santo, A., Smith, H., Peterchev, A.V., Rothwell, J.C. and Hannah, R. (2025). Distinct impacts of sodium channel blockers on the strength – duration properties of human motor cortex neurons. Epilepsia DOI: doi.org/10.1111/epi.18540