The Neurophysiological Effects of Bilateral Cerebellar rTMS on Cortical Activity and Swallowing Function

Swallowing function is controlled by two swallowing centres (one on each half of the brain). There is a dominant and non-dominant swallowing centre. Damage to any part of the brain can lead to swallowing problems, for example in strokes. Recovery of the ability to swallow is associated with increased activity (compensation) over the undamaged centre. The cerebellum is an area of the brain involved in the control and modulation of muscle movements. It is found at the back of the skull.

Over the past few years studies have tried to improve swallowing function using techniques to stimulate regions of the brain and encourage compensation. Repetitive transcranial magnetic stimulation (rTMS) is a technique which can temporarily increase or suppress activity over regions of the brain.

This study will use cerebellar rTMS to attempt to increase activity over the cortical swallowing centres. It will also temporarily suppress activity over the dominant swallowing centre (a virtual lesion) before using cerebellar targeted rTMS to attempt to reverse this suppressive electrical and behavioural effect. The investigators aim to compare the effectiveness of rTMS over the two halves of the cerebellum to rTMS over one half of the cerebellum in increasing activity over the swallowing centres and reversing the suppressive effects of low frequency rTMS 'virtual lesion' over the dominant swallowing centre.