Effect of Repetitive Transcranial Magnetic Stimulation (rTMS) of the Dorsolateral Prefrontal Cortex (DLPFC) on Hypercapnic Air Hunger Induced in Healthy Individuals.

The purpose of this study is to see if the front part of the brain called the "Dorsolateral Prefrontal Cortex" (DLPFC) has a role in our ability to feel breathlessness. The experiment will use a device that sits on the top of the head which produces a magnetic field that penetrates the scalp and excites the brain tissue directly under it. This procedure is called repetitive transcranial magnetic stimulation (rTMS), it is a painless procedure and known to be safe in healthy individuals. Previous research has shown that the pain felt when capsaicin, the active ingredient in 'chilli' powder, is applied to the hand is reduced by applying the rTMS on the scalp directly above the DLPFC part of the brain. In this experiment we want to see if breathlessness is also reduced. We will use a breathing task that will generate a moderate amount of breathlessness by adding a small amount of carbon dioxide to the inhaled air, while preventing the increase in the amount of breathing we would normally see in response to this. If we find that breathlessness produced by this breathing task is reduced after rTMS over the DLPFC, this may lead to new drugs that target this part of the brain in patients suffering from breathlessness due to heart or lung disease. The study will also improve our knowledge of how the brain enables us to feel breathlessness