Smell is unique among our senses, researcher Donald A. Wilson at New York University said. The olfactory bulb that receives nerve impulses from the nose also has direct connections to the amygdala, which controls emotions and physiology, and to higher-order regions like the prefrontal cortex, involved in cognition and planning.
"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," Wilson said. "The result is an immediate pathway from the environment through our nose to our memory."
Although impairment in the sense of smell is associated with both disease and normal aging, exactly why smell weakens has been a mystery, but Wilson said research has shown how it may happen.
"We located where in the brain loss of smell may happen," he said, saying electrical patterns in the olfactory cortex changed with changes in smell sensitivity. "And we showed that training can improve the sense of smell, and also make it worse."
"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," Wilson said.
This suggests smell training therapies could help restore smell function in some cases.
"Odor training could help fix broken noses," he says.