Dogs use their noses to ‘see’ as well as to smell, study suggests 


Dogs may be using their highly-sensitive noses to ‘see’ as well as to smell, a new study suggests. 

Researchers have discovered an ‘extensive pathway’ in the brains of domestic dogs linking areas that handle smell and vision. 

This allows dogs to have a remarkable sense of direction and awareness even when they can’t see – explaining how some blind dogs can play fetch. 

Dogs’ strong sense of smell may help them detect and distinguish between different objects and obstacles, even if they’re blind. 

 

Researchers have discovered an ‘extensive pathway’ in the brains of domestic dogs linking areas that handle smell and vision – which likely helps them know where things are even if they can’t see

WHAT IS THE NEWLY-FOUND PATHWAY? 

Researchers have an ‘extensive pathway’ in the brains of domestic dogs running between the olfactory bulb to the occipital lobe. 

The olfactory bulb is a structure located in the forebrain of vertebrates that receives neural input about odours. 

Meanwhile, the occipital lobe is the brain’s visual processing area, associated with distance and depth perception, colour determination and more. 

The new study provides the first evidence that dogs’ sense of smell is integrated with their vision and other unique parts of the brain. 

‘We’ve never seen this connection between the nose and the occipital lobe, functionally the visual cortex in dogs, in any species,’ said study author Pip Johnson, assistant professor of clinical science at Cornell University in Ithaca, New York. 

‘When we walk into a room, we primarily use our vision to work out where the door is, who’s in the room, where the table is. 

‘Whereas in dogs, this study shows that olfaction is really integrated with vision in terms of how they learn about their environment and orient themselves in it.’

The new research corroborates Johnson’s clinical experiences with blind dogs, which function remarkably well despite being unable to see. 

‘They can still play fetch and navigate their surroundings much better than humans with the same condition,’ she said.

‘Knowing there’s that information freeway going between those two areas could be hugely comforting to owners of dogs with incurable eye diseases.’ 

However, how exactly blind dogs use smell to see objects is not understood, Johnson added. 

‘Veterinarians have long wondered how dogs with complete blindness have navigated so well in their environment, even in foreign and new environments,’ she told MailOnline. 

‘The olfactory connection we identified gives us an answer to this, and shows that they are less dependent on their eyes alone and likely use olfactory information to help navigate their world.’ 

In the dog brain, information pathways run from the olfactory bulb (bottom left) to five different areas. The newly-found connection (shown in orange) links the olfactory system to the occipital lobe, the brain's visual processing area. Other networks (in blue and pink) connect the olfactory bulb to brain areas associated with memories and emotions

In the dog brain, information pathways run from the olfactory bulb (bottom left) to five different areas. The newly-found connection (shown in orange) links the olfactory system to the occipital lobe, the brain’s visual processing area. Other networks (in blue and pink) connect the olfactory bulb to brain areas associated with memories and emotions

Eileen Jenkin, a vet at Huntsville Veterinary Specialists & Emergency in Alabama who was not part of the study, described the new findings as ‘fabulous’. 

‘There have been lots of people who theorised that this connection existed, based on the behaviour of trained dogs and detection dogs, but nobody has been able to prove it,’ she told Science News.

For the study, the team performed MRI scans on the brains of 23 dogs – 20 mixed breeds and three beagles – to create digital 3D ‘maps’. 

Researchers then identified tracts of white matter that carry signals between brain regions, each of which is a bit like a ‘road network’. 

The map showed roads that connect the olfactory bulb to brain areas associated with memories and emotions. 

Humans also have this network, which is why smelling certain scents seems to transport us back in time.

But what was surprising was a new information pathway running between the olfactory bulb to the occipital lobe, the brain’s visual processing area. 

Video: Orange structure shows whole of the olfactory pathway in dogs going to multiple different regions of the brain, including the occipital lobe

‘This is the first documentation of a direct connection between the olfactory bulb and occipital lobe in any species and is a step towards further understanding how the dog integrates olfactory stimuli in their cognitive function,’ the team say.

Identifying new connections in the brains of canines also opens up avenues for further study, such as in other mammal species – possibly even humans. 

‘To see this variation in the brain allows us to see what’s possible in the mammalian brain,’ Johnson said.

‘Maybe we have a vestigial connection between those two areas from when we were more ape-like and scent-oriented, or maybe other species have significant variations that we haven’t explored.’ 

Johnson also told Science News that they aim to explore olfactory tracts of cats. 

‘Cats have the most amazing olfactory system too, and probably more connections than the dog that I can see,’ she said. 

DOGS’ BRAINS ARE NOT HARDWIRED TO RESPOND TO HUMAN FACES, EXPERTS SAY 

The brains of dogs are not hardwired to spot human faces, according to a new study, but pet pooches have learnt to use sound and scent to recognise their owners.

While humans use faces as a visual communication, they do not have a special status in the dog brain, according to a team from Eotvos Lorand University, Hungary. 

Using an MRI scanner, the team monitored brain activity in both humans and dogs as they watched two-second videos show human faces and backs of heads. 

The results from the animals showed that no part of their brains responded specifically to faces, but in humans the visual cortex lights up when it sees a face.

Researchers note that the reason dogs pay attention to human faces is because they evolved to depend on their owners and developed techniques to recognise them.

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