Researchers may have cracked the cough. Source: News Limited
MELBOURNE researchers have discovered which part of the brain controls the urge to cough, and believe it can be “turned down” to reduce the tickle in the chest during a cold.
By mapping the brains of patients with a heightened sensitivity to coughs, Florey Institute of Neuroscience and Mental Health researchers have found that the midbrain — at the top of the brain stem in the back of the head — houses the crucial communication circuit that controls the act of coughing.
Senior research fellow Michael Farrell, whose team found in previous experiments that a placebo may be the best medicine for a cough, said it appeared that signals from the airway that evoked coughing were being “amplified”, keeping the nervous system on “high alert”.
“A lot of what happens in the brain can be turned up or turned down,” Dr Farrell said.
“There are little receptors in the upper airways that send their message to the nucleus in the bottom of the brain stem.
“Once it arrives, the message goes into your brain and you have a conscious experience of something irritating your airways. It also feeds into nearby areas that orchestrate the cough reflex.
“We can’t help but wondering if there might be influences from the midbrain to turn up the size of the response of this first processing area.”
Their study involved giving both patients with cough sensitivity and healthy subjects chilli spray to inhale.
Their subjective urge-to-cough experience was measured alongside the dose. Brain scans showed that during episodes of coughing the midbrain was activated only in those with the heightened cough response.
Dr Farrell’s work on the hypersensitive cough was presented this week by PhD student Ayaka Ando at the Human Brain Mapping Meeting in Germany.
The next part of the study, using the new 7 Tesla MRI at the Melbourne Brain Centre — one of only two machines in Australia — will involve scanning the brains of cough-sensitive patients and healthy subjects while they cough, in an effort to pinpoint the specific receptor mechanism amplifying the need to cough.
“You don’t want to turn people’s cough off. That could kill you. But if we could find a way of reducing those associated sensations, it could be a really viable way of helping people manage their symptoms,” Dr Farrell said.