The purpose of the study is to determine the effects of giving 2 doses of brain stimulation through repetitive transcranial magnetic stimulation (rTMS) on swallowing neurophysiology (brain function) in healthy adults.

Recent studies have suggested that repetitive transcranial magnetic stimulation (rTMS), which is a well-established and tried and tested non-invasive (no surgical procedures involved) brain stimulation technique that can vary brain activities, may be used as a treatment for patients with swallowing difficulties. However, results have also showed that the response to the treatment is different among individuals. A possible explanation for this variation is related to the brain's level of activity preceding rTMS. The hypothesis of this study is that this variation may be minimized by regulating the brain state with an additional dose of rTMS prior to the intended rTMS session (preconditioned rTMS). This may subsequently improve the outcomes of rTMS.

Therefore, this study aims to better regulate the response of the brain to rTMS. The findings of this study will provide the basis for future development of optimal rTMS treatment protocols for patients with swallowing difficulties.

Inclusion Criteria:

• Healthy volunteers aged 18 years old or above; and
• No medical complications or significant past medical history

Exclusion Criteria:

• History of epilepsy;
• Previous history of neurosurgery;
• Previous swallowing problem;
• Implanted brain electrodes, cardiac pacemaker; or
• Use of medications (predominantly taking multiple anti-depressants) that lower neural threshold