rt-TEP (Real-Time TMS-Evoked Potential): An Informative Tool for Optimal Experimental Control and Computation of PCI in Real Time
INSTITUTION: University of Milan, Dept. Biomedical and Clinical Sciences “L. Sacco”
PROJECT LEADERS:
PI: Marcello Massimini, MD PhD; CO-PI Silvia Casarotto, PhD; Simone Russo MD
PROJECT DURATION: 3 years
This project aims to facilitate and standardize the recording of Transcranial Magnetic Stimulation (TMS)-evoked potentials (TEPs) and to compute reliable brain-based measures of consciousness at the patient’s bedside. The team has developed a user-friendly software tool, called TAAC (TMS-Adaptable Auditory Control), that allows minimizing auditory artifacts through the generation of a masking noise. The noise can be easily customized on the click sound produced by a specific TMS coil.
In addition, the team developed and implemented an informative graphical user interface, called rt-TEP (real-time TMS-Evoked Potential). This interface offers a customized readout of electroencephalography (EEG) responses to TMS in real time.
This tool offers a practical way to minimize the contribution of artifacts and maximize the impact of stimulation on the cortex, thus obtaining high signal-to-noise ratio TEPs. In addition, it represents a starting point for computing synthetic indices of brain function in real time.
The team is currently implementing an automatic procedure for real-time computation of the perturbational complexity index (PCI), which is an objective measure of consciousness previously validated on a large benchmark population in different conditions of consciousness, disconnected consciousness, and unconsciousness.
In order to further simplify the experimental setup for assessing the complexity of EEG responses to TMS at the patient’s bedside, the team has successfully interacted with the Nexstim Plc (Finland) company to integrate rt-TEP within their navigation system: this collaboration will progressively lead to a unified TMS equipment that allows to optimally control stimulation parameters through an accurate anatomical neuronavigation combined with a quantitative functional readout of EEG responses in real time. We have recently performed a live experimental session to showcase the feasibility of this approach at the 4th International Brain Stimulation Conference.
Broader Impact:
Measuring complexity with TMS-EEG represents a powerful tool to assess consciousness in challenging clinical conditions. The user interface developed here helps standardize and simplify TMS-EEG measurements for the clinical setting. The final aim is to render this technique as easy and dependable as ultrasound sonography.
Publications:
S. Casarotto, , et al., The rt-TEP tool: Real-time visualization of TMS-Evoked Potentials to maximize cortical activation and minimize artifacts. J. Neurosci. Methods 370, 109486 (2022).
S. Russo, et al., TAAC - TMS Adaptable Auditory Control: A universal tool to mask TMS clicks. J. Neurosci. Methods 370, 109491 (2022).
M. Lee, et al., Quantifying arousal and awareness in altered states of consciousness using interpretable deep learning. Nature Communications 13, 1064 (2022).
J. Ruiz de Miras, et al., Fractal dimension analysis of states of consciousness and unconsciousness using transcranial magnetic stimulation. Comput Methods Programs Biomed.175, 129-137 (2019).
Additional Information:
How to use TAAC: https://www.youtube.com/watch?v=EsAkS4X-2fA&t=7s
https://www.nexstim.com/research/nexstim-podium/
Real-time quality check of neuronavigated TMS-evoked EEG potentials: a live experimental session
Silvia Casarotto, PhD / Sasha D'Ambrosio, PhD / Mario Rosanova, MD, PhD / Simone Russo, MD / Kevin Caulfield / Matteo Fecchio, PhD
How to collect and distinguish genuine EEG responses to nTMS
Dr. Silvia Casarotto, PhD
How we can probe changes in cortical circuits with EnTMS-EEG
Dr. Marcello Massimini, MD