Failing sense of smell 'can be improved by training'

A new study, led by New York University, has found that a failing sense of smell can be improved by training therapies, pointing to possible ways to reverse the loss of smell through age or disease, the 'Nature Neuroscience' journal reported.

According to lead researcher Donald Wilson, smell was unique among people's senses. The olfactory bulb, a structure beneath the frontal cortex that receives nerve impulses from the nose, has direct connections to areas of the brain which control emotions and cognition.
"Unlike information from your eyes and ears that has gone through many connections to reach the frontal cortex, the olfactory system is just two connections away. The result is an immediate pathway from the environment through our nose to our memory," the 'Daily Mail' Wilson as saying.

Impairment in the sense of smell is associated with Alzheimer's disease, Parkinson's disease, schizophrenia, and even normal ageing, but it is not known exactly why.
In their study, the researchers trained thirsty rats to identify different smells by rewarding them with sips of water when they got it right. They then anaesthetised the rats and inserted electrodes into their brains.

They found the odours the rats could tell apart produced distinct patterns of electrical activity.

The team then gave another group of rats a drink whether they got it right or wrong. This effectively dulled their sense of smell and their brains produced similar electrical patterns in response to different odours.

"Our findings suggest that while olfactory impairment may reflect real damage to the sensory system, in some cases it may be a 'use it or lose it' phenomenon," he said.