Head direction cells efference copy") preparing the network for an impending head turn. HD cells continue to fire in an organized manner during sleep, as if animals were awake. However, instead of always pointing toward the same direction—the animals are asleep and thus immobile—the neuronal "compass needle" moves constantly. In particular, during rapid eye movement sleep, a brain state rich in dreaming activity in humans and whose electrical activity is virtually indistinguishable from the waking brain, this directional signal moves as if the animal is awake: that is, HD neurons are sequentially activated, and the individual neurons representing a common direction during wake
Pinky and the Brain question, "Are you pondering what I'm pondering?" Pinky often points out flaws in the Brain's plans, which the Brain consistently ignores. The issues Pinky brings up can ironically lead to the downfall of the given night's plot. He is also arguably Brain's moral compass and only real friend. When Pinky sold his soul to get Brain the world in "A Pinky and the Brain Halloween", Brain saved him because he missed him and the world was not worth ruling without him. Pinky also has shown signs of intelligence despite his supposed childish stupidity. In "Welcome to the Jungle", Pinky was