They smell diabetes, cancer and Covid-19. And they seem quite intrigued by the smells of poop (theirs and others). It's the dogs! You know them, with that big nose always stuck everywhere, we are well aware of their powerful sense of smell, but a recent study still amazes us.
The researcher Erica Andrews Cornell University and colleagues have just mapped the olfactory pathways in the brains of domestic dogs (canis familiaris ) using diffusion MRI scans. This technique uses differences in the flow of molecules, such as water, to create a complex map of tissue structures.
A map to understand what smells become in a dog's brain
Researchers developed three-dimensional maps of the nerve pathways in the dogs' brains and traced extensive white matter connections between the olfactory and visual systems, revealing a vast, previously unknown information pathway.
“We have never seen this connection between the nose and the occipital lobe in any other species,” explains researcher Pip Johnson. “It's something similar to what is found in the human visual system.”
In short, do dogs “see” smells? It is very likely that this is what allows our intelligent companions to operate so effectively even without sight. In the past, several people have theorized this connection empirically, but no one has proven it.
An olfactory "sorting centre".
A dog's nose by itself is extraordinarily gifted, with beyond 220 million cells which detect odors (we have less than a quarter of them). With just their noses, dogs can form spatial awareness, read chemical "messages", sense our mood, even track heat sources.
When we enter a room we use our sight to get an idea of the space we are about to cross, of the obstacles, of the presences. In dogs, smell and sight are intertwined: and not only that. The study also highlighted links with four other brain regions.
A map of the nerve tracts in the dog's brain. Just as in humans, olfactory pathways to the piriform cortex (green) and limbic system (blue) are likely to link smell to memory and emotions. It is thought that the entorhinal cortex (pink pathway) elaborate smells and also connect to memory. Another unexpected discovery, also the connections between the olfactory bulb and the brainstem through the corticospinal tract (turquoise). They can trigger “instinctive” and “automatic” responses to odors, which do not involve other areas of the brain.
The next steps
The researchers obviously warn that more research is needed before establishing exactly the function of all these connections. There is no certainty that dogs can physically “see” odors, but these findings suggest that the olfactory system plays a prominent, if not dominant, role in canine cognition.”
The conclusions of this study, that I link to you here, are the extraordinary starting point for a new journey to discover the animals that are closest to us ever.
