Our nose becomes GPS tool in total darkness

Like sniffer dogs, humans too can sniff their way, if blindfolded, towards a location whose scent they have smelled only once before, says a recent research.

Like homing pigeons, humans have a nose for navigation because our brains are wired to convert smells into spatial information, the research from the University of California, Berkeley, shows.

The results evoke a GPS-like superpower one could call an "olfactory positioning system".

"What we've found is that humans have the capability to orient themselves along highways of odours and crisscross landscapes using only our sense of smell," said study lead author Lucia Jacobs, a UC Berkeley psychology professor.

"Olfaction is like this background fabric to our world that we might not be conscious of, but we are using it to stay oriented."

"We may not see a eucalyptus grove as we pass it at night, but our brain is encoding the smells and creating a map," the researcher said.

The process of smelling, or olfaction, is triggered by odour molecules travelling up the nasal passage, where they are identified by receptors that send signals to the olfactory bulb - which sits between the nasal cavity and the brain's frontal lobe and processes the information.

A key to the connection between smell, memory and navigation is that olfactory bulbs have a strong neural link to the brain's hippocampus, which creates spatial maps of our environment.

Pigeons and rats, for example, are known to orient themselves using odour maps or "smellscapes", but sighted humans rely more heavily on visual landmarks, so the study turned up some surprising results.

Two dozen young adults were tested on orientation and navigation tasks under various scenarios in which their hearing, sight or smell was blocked.

The test location was a 25-by-20-foot room where 32 containers with sponges were placed at points around the edge of the room.

Two of the sponges were infused with essential oils such as sweet birch, anise or clove.

In the smell-only experiment, study participants were led, one at a time, into the room wearing blindfolds, earplugs and headphones and walked in circles for disorientation purposes.

They spent a minute at a specific point on the grid, where they inhaled the combination of two fragrances.

After being walked in circles again for disorientation purposes, they were tasked with sniffing their way back to the starting point where they had smelled the two fragrances.

Overall, study participants navigated relatively closely to the targeted location when using only their sense of smell, compared to when other sensory inputs were blocked.

Moreover, they were not just following one scent, but using information from both scents to orient themselves toward a point on an odour grid.

The study was published in the journal PLOS ONE.