# The Past, Current and Future Research in Cerebellar TMS Evoked Responses—A Narrative Review

## TL;DR

This review explores the use of cerebellar TMS-EEG, highlighting its potential and challenges in studying brain function and disease.

## Contribution

The paper provides a comprehensive overview of technical challenges and future directions in cerebellar TMS-EEG research.

## Key findings

- Cerebellar TMS-EEG shows promise but faces issues like muscle twitches and sensory contamination.
- Variability in experimental methods leads to inconsistent results across studies.
- Addressing technical limitations is crucial for advancing cerebellar TMS-EEG research.

## Abstract

Transcranial magnetic stimulation coupled with electroencephalography (TMS-EEG) is a novel technique to investigate cortical physiology in health and disease. The cerebellum has recently gained attention as a possible new hotspot in the field of TMS-EEG, with several reports published recently. However, EEG responses obtained by cerebellar stimulation vary considerably across the literature, possibly due to different experimental methods. Compared to conventional TMS-EEG, which involves stimulation of the cortex, cerebellar TMS-EEG presents some technical difficulties, including strong muscle twitches in the neck area and a loud TMS click when double-cone coils are used, resulting in contamination of responses by electromyographic activity and sensory potentials. Understanding technical difficulties and limitations is essential for the development of cerebellar TMS-EEG research. In this review, we summarize findings of cerebellar TMS-EEG studies, highlighting limitations in experimental design and potential issues that can result in discrepancies between experimental outcomes. Lastly, we propose a possible direction for academic and clinical research with cerebellar TMS-EEG.