Scientists have confirmed that dogs "see" the world through their noses

Scientists have obtained the first anatomical evidence that the olfactory bulbs in dogs are directly connected to different areas of the cerebral cortex. This suggests that the sense of smell of animals is inextricably linked with their cognitive functions. StudyExtensive Connections of the Canine Olfactory Pathway Revealed by Tractography and Dissection this was published in The Journal of Neuroscience by a team of biologists from the College veterinary medicine at Cornell University, Johns Hopkins University and Columbia University university.

The study says that the connection found in dogs between the areas of the brain responsible for smell and vision has not previously been observed in any species, including humans. Dogs literally "see" the world with their noses.

In a sense, these results are not surprising, noted Pip Johnson, veterinary radiologist and neuroimaging expert. Dogs are known to have an excellent sense of smell. Their noses contain 200 million to 1 billion olfactory receptors, compared to 5 million in humans. And the olfactory bulbs of dogs can be 30 times larger than those of humans.

To map the connections between brain regions, the researchers examined 20 mixed-breed dogs and three beagles. The subjects all had long noses and medium-sized heads, and they were all probably good sniffers.

Non-invasive diffusion spectral tomography was applied to all dogs and a map was made showing the path of the chain of neurons. As a result, scientists identified five different tracts from the olfactory bulb:

• one links the olfactory system to the visual cortex (orange);
• the second leads to the cortical region of the spinal cord (turquoise), which helps trigger instinctive behavior;
• the third to the pear-shaped lobe (green), which may play a role in odor perception;
• the fourth - to the limbic system (blue), associated with behavior and emotions;
• and the fifth leads to the entorhinal cortex (pink), which helps process memories.

This new map of the dog's brain contains some familiar pathways, including those that connect the olfactory bulb to areas of the brain associated with memories and emotions. In humans, these same connections explain why, for example, the smell of perfume or some kind of food can take a person into the past.

The most remarkable was the orange tract, which confirmed the connection between smell and vision. Perhaps this anatomical feature may be why a dog's good sense of smell often compensates for vision loss, Pip Johnson noted.