I
n 1954, scientists James Olds and Peter Milner ran some experiments on rats in a laboratory at McGill University. What they found was remarkable and disturbing. They discovered that if electrodes were implanted into a particular part of the rat brain—the lateral hypothalamus—rats would voluntarily give themselves electric shocks. They would press a lever several thousand times per hour, for days on end, and even forgo food so that they could keep pressing. The scientists discovered that the rats were even prepared to endure torture in order to receive these shocks: The animals would run back and forth over an electrified grid if that’s what it took to get their fix. They enjoyed the shocks so much that they endured charring on the bottoms of their feet to receive them. For a long time afterward, Olds and Milner thought that they had discovered the “bliss center” of the brain—but this was wrong. They had discovered the rewardcenter. They had found the part of the brain that gives us our drives and our desires. These scientists assumed that the rats must have been in a deep state of pleasure while receiving these electric shocks, but in reality they were in a prolonged state of acute craving.