
In animal studies, Kate Jeffery and her colleagues analyzed two types of nerve cells involved in the brain's representation of space: those that measure distance and those that indicate location. Curiously, the first ones were not activated when the animals climbed and ascended. "The perception of space is quite flat, since we are sensitive to where we are placed on a horizontal plane, but only vaguely aware of altitude," concludes Jeffery in a study published in the journal Nature Neuroscience . This has negative implications for professionals who have to move freely in three dimensions, such as divers, pilots, and astronauts , for example.