Jennifer Ouellette in Ars Technica:
How the brain fixes the timing of the events we experience depends on episodic memory. Whenever you remember key events from your past, you are tapping into episodic memory, which encodes what happened, where it happened, and when it happened, doing so for all our remembered experiences. Neuroscientists know the brain must have a kind of internal clock or pacemaker to help it track those experiences and record them as memories.
In a new paper in Nature, researchers at the Kavli Institute for Systems Neuroscience (KISN) in Norway report that they have pinpointed a collection of interconnected brain cells that provides this clock. And it just happens to be located right next to the brain region that keeps track of where we are in space.
Scientists have known how the brain encodes the aspect of space in our memories since 2005, with the Nobel Prize-winning discovery of grid cells. These reside in a brain region called the medial entorhinal cortex (MEC), and they collectively map our environment into hexagonal units.
More here.