Study gives new insight into how the brain perceives places

By Carol Clark | eScienceCommons | Oct. 30, 2018

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Example of an image from the fMRI study. Participants were asked to imagine they were standing in the room and indicate through a button press whether it was a bedroom, a kitchen or a living room. On separate trials, they were asked to imagine that they were walking on the continuous path through the room and indicate which door they could leave through. Image by Andrew Persichetti.

Nearly 30 years ago, scientists demonstrated that visually recognizing an object, such as a cup, and performing a visually guided action, such as picking the cup up, involved distinct neural processes, located in different areas of the brain. A new study shows that the same is true for how the brain perceives our environment — it has two distinct systems, one for recognizing a place and another for navigating through it.

The Journal of Neuroscience published the finding by researchers at Emory University, based on experiments using functional magnetic resonance imaging (fMRI). The results showed that the brain’s parahippocampal place area responded more strongly to a scene recognition task while the occipital place area responded more to a navigation task.

The work could have important implications for helping people to recover from brain injuries and for the design of computer vision systems, such as self-driving cars.

“It’s thrilling to learn what different regions of the brain are doing,” says Daniel Dilks, senior author of the study and an assistant professor of psychology at Emory. “Learning how the mind makes sense of all the information that we’re bombarded with every day is one of the greatest of intellectual quests. It’s about understanding what makes us human.”

Entering a place and recognizing where you are — whether it’s a kitchen, a bedroom or a garden — occurs instantaneously and you can almost simultaneously make your way around it.

“People assumed that these two brain functions were jumbled up together — that recognizing a place was always navigationally relevant,” says first author Andrew Persichetti, who worked on the study as an Emory graduate student. “We showed that’s not true, that our brain has dedicated and dissociable systems for each of these tasks. It’s remarkable that the closer we look at the brain the more specialized systems we find — our brains have evolved to be super efficient.”

Persichetti, who has since received his PhD from Emory and now works at the National Institute of Mental Health, explains that an interest in philosophy led him to neuroscience. “Immanuel Kant made it clear that if we can’t understand the structure of our mind, the structure of knowledge, we’re not going to fully understand ourselves, or even a lot about the outside world, because that gets filtered through our perceptual and cognitive processes,” he says.

The Dilks lab focuses on mapping how the visual cortex is functionally organized. “We are visual creatures and the majority of the brain is related to processing visual information, one way or another,” Dilks says.

Researchers have wondered since the late 1800s why people suffering from brain damage sometimes experience strange visual consequences. For example, someone might have normal visual function in all ways except for the ability to recognize faces.

It was not until 1992, however, that David Milner and Melvyn Goodale came out with an influential paper delineating two distinct visual systems in the brain. The ventral stream, or the temporal lobe, is involved in object recognition and the dorsal stream, or the parietal lobe, guides an action related to the object.

In 1997, MIT’s Nancy Kanwisher and colleagues demonstrated that a region of the brain is specialized in face perception — the fusiform face area, or FFA. Just a year later, Kanwisher’s lab delineated a neural region specialized in processing places, the parahippocampal place area (PPA), located in the ventral stream.

While working as a post-doctoral fellow in the Kanwisher lab, Dilks led the finding of a second region of the brain specialized in processing places, the occipital place area, or OPA, located in the temporal stream.

Dilks set up his own lab at Emory the same year that discovery was published, in 2013. Among the first questions he wanted to tackle was why the brain had two regions dedicated to processing places.

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