Sleep is far from an inactive time for the brain: while rats (and humans) are asleep, neurons in the hippocampus fire rapidly. After a rat has repeatedly moved from one spot to another, the same neurons that fired while the rat moved "replay" this firing while the rat is asleep, i.e. they fire in the same, but much quicker, pattern. Previously, it was thought that replay patterns only correspond to trips rats had made repeatedly while awake. Writing in Neuron today, Postdoc Federico Stella and Professor Jozsef Csicsvari at the Institute of Science and Technology Austria (IST Austria), show also that when rats roam around freely, the hippocampus replays during sleep, but it does so in a random manner that resembles the famous Brownian motion known from randomly moving particles.
* This article was originally published here
