Researchers at Cornell University have found that dogs’ sense of smell is connected with their vision and other unique parts of the brain. Their study is the first documentation of the link between dogs’ vision and smell.
The finding sheds new light on how dogs experience and navigate the world. The study titled describing the results was recently published in The Journal Of Neuroscience.
The olfactory sense of the domestic dog is widely recognised as being highly sensitive with a diverse function, but little is known about the structure of their olfactory system, the authors noted in the study.
Findings
The researchers identified an extensive pathway composed of five white matter tracts connecting to the occipital lobe, corticospinal tract, piriform lobe, limbic system, and entorhinal pathway. Corticospinal tract is the major spinal pathway involved in voluntary movements. Piriform lobe is a unique brain region that manages olfactory experiences. The limbic system is involved in behavioural and emotional responses. The functions of the entorhinal pathway involve memory, navigation, and perception of time.
The study is the first documentation of a direct connection between the olfactory lobe and occipital lobe in any species, and is a step towards further understanding of how the dog integrates olfactory stimuli in their cognitive functioning, the authors noted.
Study Identifies Never-Before-Seen Connections
In a statement released by Cornell University, Pip Johnson, senior author on the paper, said the researchers have never seen this connection between the nose and the occipital lobe, functionally the visual cortex in dogs, in any species. The occipital lobe is the visual processing area of the brain, and is associated with distance and depth perception, colour determination, and memory formation.
She said when one walks into a room, they primarily use their vision to work out where the door is, who is in the room, where the table is. The study shows that in dogs, olfaction is integrated with vision in terms of how they learn about their environment and orient themselves in it, she added.
The regions where the brain processes memory and emotion had connections to olfaction, similar to those in humans. Also, never-documented connections of olfaction to the spinal cord and the occipital lobe were observed. These connections are not observed in humans.
According to the statement, the research corroborates Johnson’s clinical experiences with blind dogs, who function remarkably well. Johnson said blind dogs can still play fetch and navigate their surroundings much better than humans with the same condition. She added that knowing there is an information freeway going between those two areas could be hugely comforting to owners of dogs with incurable eye diseases.
Johnson explained that to see this variation in the brain allows researchers to see what is possible in the mammalian brain and to wonder whether other species have significant variations that have not been explored.