DARK AND MAGICAL PLACES

The latest knowledge on how we find our way.

Kemp, a molecular biologist specializing in neurodegenerative diseases, admits that he gets lost in his native city. So he admires virtuoso navigators, like his wife, who always know where they are. This short book delivers an expert education in how the brain guides us. As the author shows, it’s not a matter of intelligence; plenty of smart people lose their way. The key is memory, largely centralized in the hippocampus, a small structure deep inside the skull atop the brainstem that’s literally packed with cells vital to our sense of direction. Licensed London cab drivers, who must memorize every one of the city’s 25,000 streets, possess a hippocampus much larger than London bus drivers, who only memorize a single route. The first symptom of Alzheimer’s is not memory loss but inability to navigate. “Essentially,” writes Kemp, “navigation is…a seamless combination of sensory memory, and short-term and long-term memories spliced together, interpolated and intertwined with one another by the hippocampus and other related brain structures.” Early knowledge on the subject arose from studies of rats and mazes, and the Einstein of rat navigation was Edward Tolman. According to Kemp, Tolman’s 1948 paper, “Cognitive Maps in Rats and Men,” is a work that "should sit alongside other great scientific discoveries of the twentieth century.” Tolman’s rats did not memorize a series of turns to achieve their goal; rather, they built a cognitive map of the maze, which is not topologically accurate but superb for choosing a precise route. Except for two illustrations, Kemp relies on prose to explain a complex process involving dozens of structures and specialized neurons throughout the brain. Readers with a well-developed hippocampus will have an easier time, but everyone will appreciate the author’s stories of how some Indigenous cultures learn their territory (they get lost, too) and concluding sections on how to become a better navigator and how to behave if lost in the wild.

An intense lesson in the neuroscience of getting around.