Here's how our brains help us navigate in the dark

A new study, with the help of virtual reality, has shed new light on how people navigate in the dark.

A series of immersive virtual reality experiments has now confirmed that the human brain's internal navigation system works in the same fashion as the grid cell system, a specialized neural network discovered in rats only 10 years ago, which has since been identified in a number of other mammals, including mice, bats and monkeys.

Vanderbilt University's Timothy McNamara and his collaborators Xiaoli Chen, Qiliang He, Jonathan Kelly from Iowa State University and Ila Fiete from the University of Texas, became interested in a series of experiments where the researchers had recorded how the rat's grid cell system responds when the size of the its enclosure is altered.

The researchers who performed the experiments found that the grid spacing increased when the enclosure was enlarged and decreased when the enclosure shrunk.

McNamara added that in most cases, the participants don't even notice that the size of the enclosure has changed, but, when it does change, the positions where they stop are significantly farther from the target than they are when the enclosure remains the same. When the enclosure increases in size they tend to undershoot and when it decreases they tend to overshoot.

The amounts that the participants undershot and overshot were remarkably consistent with what the studies with rats and Fiete's model predicted if the individuals were being guided by a grid-cell system that had been fixed by the dimensions of the original enclosure.

McNamara noted that they still can't say for certain that people use a grid-cell system to navigate, but they can say that, if people use a different system, it seems to behave in exactly the same way.

The study will appear in the June 29 issue of the journal Current Biology.