Animals navigate by calculating their current position based on how long and how far they have traveled.
A new study on treadmill-running rats reveals how: neurons called grid cells integrate information about time and distance to support memory and spatial navigation, even in the absence of visual landmarks.
The findings, published November 4 in the journal Neuron, challenge currently held views of the role of grid cells in the brain.
“Space and time are ever-present dimensions by which events can be organized in memory,” says senior study author Howard Eichenbaum, a psychologist and neuroscientist at Boston University. “These findings support the view that memory evolved as a common function in mammals using circuits that organize events in space, time, and potentially many other dimensions of experience.”
Past research has shown that grid cells receive information from other cells about the direction traveled. But until now, there was no direct evidence showing that grid cells signal distance or time, leaving its role in path integration merely speculative.