Seeking: How the brain hard-wires us to love Google, Twitter, and texting. And why that's dangerous. By Emily Yoffe
[Olds] eventually discovered that if the probe was put in the brain's lateral hypothalamus and the rats were allowed to press a lever and stimulate their own electrodes, they would press until they collapsed.
Olds, and everyone else, assumed he'd found the brain's pleasure center (some scientists still think so). Later experiments done on humans confirmed that people will neglect almost everything—their personal hygiene, their family commitments—in order to keep getting that buzz.
But to Washington State University neuroscientist Jaak Panksepp, this supposed pleasure center didn't look very much like it was producing pleasure. Those self-stimulating rats, and later those humans, did not exhibit the euphoric satisfaction of creatures eating Double Stuf Oreos or repeatedly having orgasms. The animals, he writes in Affective Neuroscience: The Foundations of Human and Animal Emotions, were "excessively excited, even crazed." The rats were in a constant state of sniffing and foraging. Some of the human subjects described feeling sexually aroused but didn't experience climax. Mammals stimulating the lateral hypothalamus seem to be caught in a loop, Panksepp writes, "where each stimulation evoked a reinvigorated search strategy" (and Panksepp wasn't referring to Bing).
University of Michigan professor of psychology Kent Berridge has spent more than two decades figuring out how the brain experiences pleasure. Like Panksepp, he, too, has come to the conclusion that what James Olds' rats were stimulating was not their reward center. In a series of experiments, he and other researchers have been able to tease apart that the mammalian brain has separate systems for what Berridge calls wanting and liking.
Wanting is Berridge's equivalent for Panksepp's seeking system. It is the liking system that Berridge believes is the brain's reward center. When we experience pleasure, it is our own opioid system, rather than our dopamine system, that is being stimulated. This is why the opiate drugs induce a kind of blissful stupor so different from the animating effect of cocaine and amphetamines. Wanting and liking are complementary. The former catalyzes us to action; the latter brings us to a satisfied pause. Seeking needs to be turned off, if even for a little while, so that the system does not run in an endless loop. When we get the object of our desire (be it a Twinkie or a sexual partner), we engage in consummatory acts that Panksepp says reduce arousal in the brain and temporarily, at least, inhibit our urge to seek.