David Rubenstein's Reviews > Dark and Magical Places: The Neuroscience of Navigation

How do we navigate? What parts of the brain are responsible for our ability to navigate? Why are some people really good at navigation, while others are terrible? Can you train yourself to be a better navigate? What allows certain animals to be master navigators?

This book discusses all these questions, and sometimes the answers are surprising. Neuroscientists have discovered that so-called "place cells" fire in the hippocampus portion of the brain, coding for location. Perhaps about 10,000 place cells fire in a pattern to represent a particular location. Maybe 20% of the hippocampus is devoted to these place cells. So-called "sharp-wave ripples allow us to mentally simulate future possibilities, and map out routes. There are also head direction cells that act like the needle of a compass. When they fire, they have among the highest signal-to-noise ratio of all neurons in the brain. They help to give us an absolute (not relative) sense of direction.

Women and men navigate differently. Men rely on cardinal directions and metric distances, while women rely more on memories of landmarks. Men perform better at mental rotation tasks, while women are better in tests of location memory.

Some scientists believe that this is in agreement with the hunter-gatherer theory. Mental rotation is useful for hunting, while location memory is more useful for gathering food. Modern women seem to be better at remembering the locations of school textbooks, spare house keys, and homework folders. However, some anthropologists say that this is all nonsense! A few hours spent playing a video game can erase these differences.

In countries where men and women are treated equally, both sexes have good navigation skills. But in countries where women are treated as second-class citizens, and forbidden to drive, they score worse in navigational tests. This isn't too surprising. Interestingly, people who perform best at smell identification tests also do best at navigation. It seems like spatial memory and olfaction are linked.

Released in a forest, people can walk in a straight line for hours on a clear day, using the sun as a guide. But on an overcast day, few people could walk further than a mile from their starting point, as they backtrack and loop erratically. GPS guidance is degrading our ability to navigate. GPS maps show fewer landmarks, which are needed for navigation. Scientists have shown that when using a GPS, neurons in the hippocampus are flatlined!

Many books on psychology mention the significantly enlarged hippocampus found in London taxi drivers. They spend years learning all the roads in London, in preparation for a taxi-driving entrance exam. This book, however, points out that the volume in a brain is finite. An enlargement of one portion of the brain means that other portions must be somewhat smaller, as a result.

The author, Christopher Kemp, is a molecular biologist. He writes in a straightforward style, avoiding cutesie humor. He brings lots of interesting anecdotes to the narrative. My only problem with the book occurs on page 143, where he demonstrates a misunderstanding of statistics and test scores. Nevertheless, this is a short and engaging book. It deserves to be read by anyone who finds navigation to be important in daily life.