Cerebellar iTBS Modulates Neural Dynamics Underpinning Sense of Self

You are invited to participate in a brain stimulation experiment that investigates how our brain processes information about our own body. In this project we are studying how specific patterns of activity in the brain support our sense that our own body belongs to us. New knowledge in this area is not only of great scientific value, it can also help us understand how neurological and psychiatric conditions where participants experience their own body in an unusual manner, such as schizophrenia.

We are recruiting right-handed, neurotypical adults (aged 18 – 49) who have normal or corrected to normal vision. You must not have any neurological or psychological conditions, or a previous history of such conditions. You also must not have any metal objects in your body. A medical screening questionnaire will be conducted before the experiment to ensure that it is safe for you to participate.

The medical screening questionnaire will ensure you meet the following criteria to participate:
- Must not suffer from any neurological or psychiatric conditions
- Must never have suffered from epilepsy, febrile convulsions in infancy, or unexplained fainting
- No members of immediate family suffering from epilepsy
- Must never have undergone a neurosurgical procedure
- Must not have a heart pacemaker, cochlear implant, medication pump, or surgical clips
- Must not be taking medications which alter the risk of seizure (will be confirmed by experimenter)
- Must not be undergoing anti-malarial treatment
- Must not be pregnant

You will be called in for three experimental sessions on three different days, which will take place as follows:

First a screening session will determine that you are eligible for the experiment. You will complete the medical screening questionnaire, a short bodily illusion test to determine your susceptibility to body illusions, and a TMS eligibility test. The TMS eligibility test uses a strong magnetic pulse to very briefly affect the activity in a specific area of the brain. First, we will place the TMS stimulator over a part of the cerebral cortex that controls a specific muscle in your hand. When we stimulate, a finger will twitch slightly and we measure the muscle contraction using a pair of electrodes that we attach to the skin of the hand. In total this session will last around 30 minutes.

In the experimental sessions, you will complete a short bodily illusion test before and after receiving Transcranial Magnetic Stimulation. The illusion involves sitting still whilst a small robotic arm touches your hand (which is obscured from view) and a fake rubber hand simultaneously. You will be asked questions regarding your experiences during the illusion.

Then we apply transcranial magnetic stimulation (TMS) over your head. We place the TMS stimulator over the back of your head and stimulate for 3 minutes. After, you will complete the illusion test again as before. There will be two experimental sessions, each lasting approximately two hours.

This experiment has been approved and reviewed by the Swedish Ethics Review Authority.

For participating, you will receive financial compensation equivalent to 250 SEK per hour for completing all sessions, or 1125 SEK total (taxable). Please note - so that we may pay the compensation, you must have a personnummer.

For more information regarding participation in the study, please contact the lead researcher (Dr. Haydn Farrelly) via email.