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Jun 19, 2020

How do our brains navigate the world?

It’s a longstanding joke that dads are too proud to ask for directions, but they might be onto something: relying more and more on outside guidance like GPS to navigate has implications beyond getting from one place to another. Spatial cognition is a predictor of IQ and of performance in the STEM fields—it’s an aspect of intelligence that we shouldn’t just cede to technology.

A number of studies over the past few decades have found that men perform better on spatial cognition tests than women. However, those findings have recently come under scrutiny. When females are confident in their spatial cognition testing abilities, their performance is on par with males’. And, a new study by Adam Toth and Mark Campell out of Limerick, Ireland further suggests that some of the older conclusions have been exaggerated, noting that when test “criteria are manipulated, the sex difference diminishes. For example, when participants are not time constrained...the sex difference is significantly diminished and even abolished.”

Determining spatial aptitude is usually done by asking test subjects whether a rotated version of a 3D cube image (think of a Tetris piece) is a match, is a mirror image, or has structural differences from the original shape. The mental rotation test (MRT) involved in Toth and Campbell’s study additionally tracked where people focused their gazes, to understand how people approached the problem. Women and men did approach the task slightly differently, with men more likely to guess, and women behaving somewhat more cautiously. That might account for why removing time constraints erased the sex differences previously seen: when women were given time to complete the test, their scores were as high as men’s.

Given the number of studies over the previous decades investigating sex differences in spatial cognition, it seems that the jury is still out on this subject. And it’s just one among many questions that scientists are still investigating when it comes to navigation and the brain

One unexpected theory accounting for spatial cognition differences involves language. As Stanford psychologist Lera Boroditsky explained to Newsweek and Radiolab, certain communities in Australia use cardinal-direction-related speech that constantly orients speakers within the space around them. Instead of greeting a friend with “How are you?” they might ask, “Where are you going?” and be answered “North-northeast in the middle distance, how about you?” As Boroditsky reports, the aboriginal community in Pormpuraaw envision themselves moving through space, as if from a bird’s eye view. That habit fits with their ability for dead reckoning that was previously only attributed to animals, like ants and pigeons. Dead reckoning involves estimating the direction and distance you’ve traveled, based on how long it took you to get from an initial to a known position.

Something akin to dead reckoning is what homing pigeons are known for: they can find their way home, even when they don’t know where they are. In one set of experiments, homing pigeons were put in dark boxes and flown thousands of miles away by plane. They had no problem returning. Suspecting that scent guided them, scientists at the Cornell Lab of Ornithology subjected them to anaesthesia en route to a new place. Still, they returned home. According to neurobiologist Charles Walcott, it's now thought that magnetic sensors in their beaks account for much of their orienteering—that is, they have a sort of built-in compass—though their amazing navigational abilities are still not fully understood.

Given the absence of beaks in most humans, one might wonder where in the mammalian brain spatial orientation occurs. A study led by Kenneth Kay of Loren Frank’s UCSF lab recorded neurons in the hippocampus called ‘place cells’, which act as the brain’s GPS system. Rats were placed in an M-shaped maze, and as they approached a decision-making point, neural activity in the rats’ place cells showed alternating patterns, suggesting that the rats were mentally testing going in two different directions. Rather than the place cells firing just in the moment of choosing a path, it seems the rats were considering beforehand what might happen if they chose one way versus another. That is, they were imagining hypothetical scenarios about the future.

Indeed, says Kay, “The regular switching between present and possible — or actual and imagined — looks like a robust system for generating lots of ideas, not just for mechanically remembering or predicting,” Kay said. “The hippocampus could be at the root of our ability to imagine.” This is all to say that intentionally imagining oneself in space, like the Australians Boroditsky observed, could hold a key for those of us who are directionally challenged. And, Dad might not be trying to frustrate his passengers (though he’s definitely doing that, too) when he insists he’ll find the way: he may be wisely honing his navigational skills.

By Aimee Fountain

References: https://neurosciencenews.com/brain-navigation-imagination-15607/








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