An abnormality in the reflex that stops breathing when food "goes down the wrong way" may be a cause of cot death, scientists say.
If co-ordination of breathing and swallowing is lost owing to an irritant entering the airway, it may have fatal implications for the baby, they added.
Researchers at Macquarie University in Sydney, Australia, have identified two areas of the brain that work together to control breathing and swallowing to enable breathing without choking. They say that with increased understanding of these brain areas they may be able to identify what goes wrong in Sudden Infant Death Syndrome.
The reflex that closes the airway and triggers coughing and swallowing when food enters it is vital for everyone but it is especially important in babies because they have a tendency to regurgitate liquids after feeding. Saliva also tends to pool in their throats
However, the reflex is also risky as if breathing stops for a period of time blood oxygen levels can drop to dangerously low levels.
Prof Paul Pilowsky, who led the study, published in The Journal of Physiology, said: "The closing of the airway in adults is only a small compromise as breathing is only stopped temporarily. But for babies the response has more radical implications, particularly if breathing stops for a long time, as they can't take in oxygen or get rid of carbon dioxide.
"The timing of breathing and swallowing is exquisitely co-ordinated. We suspect that co-ordination of the two may be going awry in sudden infant death syndrome (SIDS), but to be sure of this, we need to know how the brain organises this response in the first place."
Working with rats, the scientists used electrical stimulation to mimic the brain and body's response to a throat irritant. By measuring neural activity linked to the reflex the team hopes to get a better understanding of what causes the brain to halt breathing for long periods.
Scientists believe poor co-ordination between two parts of the brain that work together to control breathing and swallowing might play a key role in (Sids).
The reflex brings the vocal chords together to trigger coughing and swallowing.
Prof Pilowsky added: "The next step is to work out why these regions 'decide' whether breathing should be stopped. The eventual hope is to have the ability to manipulate these two systems separately to prevent the excessively long breathing arrest that may cause SIDS."
Previous research in the UK has shown that more than half of cot deaths happen when a baby is sleeping with a parent.Researchers said this could be linked to the baby's parent having been drinking or taking drugs, before falling asleep with the baby in bed or on a sofa. ( © Independent News Service)