Effects of Repetitive Transcranial Magnetic Stimulation on Two Cerebellar Targets

Condition(s) studied

Investigational drug(s) / intervention(s)

Active rTMS - Lobule VIII: Either excitatory (e.g., iTBS) or inhibitory (e.g., cTBS) depending on the assigned group.

Active rTMS - Crus I/II: Participants receive rTMS targeting the Crus I/II of the cerebellum. Either excitatory (e.g., iTBS) or inhibitory (e.g., cTBS) depending on the assigned group.

Sham rTMS: The coil looks and sounds identical to the active coil and is placed in the same positions (counterbalanced between Lobule VIII and Crus I/II sites). It provides the physical sensation and auditory "click" of TMS without delivering a significant magnetic field to the brain tissue, maintaining the study's double-blind integrity.

Cognitive and Motor Assessment Battery: Participants perform three computerized tasks to evaluate the functional impact of the rTMS: * Visuomotor Task: A joystick-based task assessing motor coordination and learning (linked to Lobule VIII). * Temporal Prediction Task: A visual task requiring the participant to predict the timing of an event (linked to Crus I/II). * Mental Imagery \& Finger Tapping: A task assessing the cognitive representation of movement.

Study summary

The purpose of this study is to understand how different areas of the cerebellum (a part of the brain) control different functions and how they can be influenced by non-invasive brain stimulation.

While researchers know that repetitive Transcranial Magnetic Stimulation (rTMS) can have positive effects on conditions like stroke and schizophrenia, they do not yet fully understand which specific stimulation settings work best or which exact parts of the cerebellum should be targeted for different symptoms.

This study compares the effects of stimulation on two specific regions:

* Lobule VIII: Linked to movement and motor learning.
* CRUS I/II: Linked to attention, thinking (cognition), and predicting the timing of events.By comparing these areas, researchers hope to gain the information needed to develop better treatments for neurological and psychiatric disorders.

This is a randomized, double-blind study involving 40 healthy volunteers. Participants will be split into two groups:

* Group 1: Receives "exciting" (activity-increasing) stimulation.
* Group 2: Receives "inhibiting" (activity-decreasing) stimulation.

Each participant will attend three different test sessions in a random order:

* rTMS targeting Lobule VIII
* rTMS targeting CRUS I/II
* Placebo (Sham) stimulation that looks and feels like the real thing but does not affect the brain.

During each session, researchers will use brain imaging (fMRI) and computerized tasks to measure changes in brain connectivity and performance in motor and cognitive activities.

There is no direct medical benefit to the participants. However, the results will help scientists create better therapies for patients with brain-related health issues The risks are considered minimal. Common side effects of rTMS include temporary mild headaches or a clicking sound during stimulation. MRI scans can sometimes cause mild discomfort or a feeling of closed-in spaces (claustrophobia). Researchers have put safety measures in place, such as hearing protection and constant medical supervision during scans, to minimize these risks.

Eligibility

Primary outcome measure(s)

• Change in Resting-State Functional Connectivity (RSFC) Measured by functional Magnetic Resonance Imaging (fMRI, expressed as Fisher's z-transformed correlation coefficients) within Cerebellar-Thalamo-Frontal and Cerebellar-Parieto-Motor Networks. — Baseline (Pre-stimulation) and 1-hour post-stimulation
  Functional imaging data will be pre-processed according to standard procedures: slice-timing correction, intra-run spatial realignement, inter-run realignement, distortion and motion artifact correction, band-pass filtering to remove physiological noise, and normalization into the MNI common space, followed by smoothing using FSL and SPM12 software.Subsequently, the signal within the networks of interest will be extracted using the "Conn" toolbox and compared using a General Linear Model (GLM). Connectivity maps will be generated from specific "seed" regions of interest (Crus I/II and lobule VIII), where each voxel value corresponds to the correlation with the seed region.

Trial sites (1)

More University Hospital, Strasbourg, France trials in France

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