TMS-EEG Methods

Non-invasive Brain Stimulation (TMS)-EEG Methods. Combining TMS with EEG can be very powerful in understanding normal brain network interaction, as well as abnormal brain network activity. Particularly promising are multisensory and sensorimotor frameworks for TMS-EEG. However, there are numerous methodological hurdles to using TMS-EEG, cleaning the data, and interpretation of the data. I develop methods for analysis of TMS-evoked and -induced network activity. My work examines sensory contributions to the TMS-EEG signal, called the Vertex Potential (VP, also called the auditory evoked potential, AEP). I developed and tested an Independent Components Analysis-based technique for isolating the VP and show that the TEP remaining after removal of VP is unique to stimulation site and to individual subjects and can provide insight into TMS-evoked potentials as well as other-modulated oscillatory dynamics. Due to multisensory or non-model contributions to the VP, an ICA-based removal technique may not always be appropriate. For these cases, I provide another method for dealing with the VP. I show that additional multisensory masking, as well as using a predictable TMS pulse timing, can reduce the VP and reports of perception significantly more than the most commonly used masking protocol. I call this combination the ATTENUATE protocol. It uses concepts from sensory neuroscience to minimize the sensory potential in the TEP. I show superiority with ATTENUATE to standard masking techniques. In other work, I examine the efficacy of using single pulse TMS to probe network modulation after individual rTMS trains.

  1. Ross, J.M., Sarkar, M., & Keller, C.J. (2022). Experimental suppression of transcranial magnetic stimulation-electroencephalography sensory potentials. Human Brain Mapping, 1-3. doi: 10.1002/hbm.25990
  2. Ross, J.M., Ozdemir, R.A., Lian, S.J., Fried, P.J., Schmitt, E.M., Inouye, S.K., Pascual-Leone, A., & Shafi, M.M. (2022). A structured ICA-based process for removing auditory-evoked potentials. Scientific Reports, 12, 1391.
  3. Ashburn, S.M., Abugaber, D., Antony, J.W., Bennion, K.A., Bridwell, D., Cardenas-Iniguez, C., Doss, M., Fernández, L., Huijsmans, I., Krisst, L., Lapate, R., Layher, E., Leong, J., Li, Y., Marquez, F., Munoz-Rubke, F., Musz, E., Patterson, T.K., Powers, J.P., Proklova, D., Rapuano, K.M., Robinson, C.S.H., Ross, J.M., Samaha, J., Sazma, M., Stewart, A.X., Stickel, A., Stolk, A., Vilgis, V., Zirnstein, M. (2020). Toward a socially responsible, transparent, and reproducible cognitive neuroscience. In M. Gazzaniga & R. Mangun (Eds.), The Cognitive Neurosciences VI. Cambridge, MA: MIT Press.


Figure 1. TMS-evoked potentials (TEPs) before and after ICA-based removal of sensory vertex potential in TMS-EEG (VP, also called the auditory evoked potential, AEP). The VP is evoked by the sound of single pulses of TMS. We developed and tested an Independent Components Analysis-based technique for isolating the VP. We show that the TMS-evoked potential (TEP) remaining after removal of VP using this technique is unique to stimulation site and to individual subjects and may contain other-modulated oscillatory dynamics in the alpha band. Figure adapted from Ross et al., 2022, Sci. Rep.

Figure 2. A TMS-evoked potential (TEP) capturing a large sensory vertex potential (VP). Due to multisensory or non-model contributions to the VP, our ICA-based removal technique may not always be appropriate. For these cases, we show that additional multisensory masking, as well as using a predictable TMS pulse timing, can reduce the VP and reports of perception significantly more than the most commonly used masking protocol. We call this combination the ATTENUATE protocol. It uses concepts from sensory neuroscience to minimize the VP in the TEP. Figure adapted from Ross et al., 2022, Hum. Brain Mapp.