Several months ago, Matthew Wilson, a neuroscientist at the Massachusetts Institute of Technology, announced that he had figured out what the rats in his lab dream about. Wilson and his graduate assistant Kenway Louie had implanted tiny electrodes directly into the rats' hippocampi, the region responsible for memory and learning. Then they trained the rats to scurry around a circular track and stop periodically for food rewards. As the rats ran, the electrodes monitored the firing of a dozen or so neurons in each rat's brain. Wilson found that the neurons fired in a distinctive pattern that varied from rat to rat but remained the same for each individual animal.
Later, when the rats experienced rapid eye movement sleep, those neurons began to fire again. "The patterns are not exactly the same," Wilson says, "but we can definitely say that they are derived from those generated during the rats' awake experience on the track." Apparently the rats' nocturnal visions are constructed from the mundane events of their daily lives, replayed in detail. In some cases, Wilson and Louie could even tell where on the track the animal dreamed it was.
Humans, of course, dream about events long past as well as about more recent ones, and Wilson speculates that some rat dreams may be just as convoluted as ours. His rats led a sheltered, uneventful existence before they were introduced to the track and an equally boring life after, which he suspects left them with simple dreams. "You have a past to dream about," he says. "The task we engage them in and their normal behavior in their cage are the only experiences they ever have, so that's what they replay."
Researchers have long known that animals experience dreamlike states, but Wilson's experiment breaks new ground, offering a clue to why humans dream. Wilson suspects his rats relive their wanderings as they dream to consolidate events into their long-term memory— in short, to learn. In his next experiments, he will test how teaching rats a variety of tasks influences their dreams.
Discover's editors found Wilson's research fascinating but also noted that there is something inherently funny— and humbling— in the idea that rats dream at all. Freud turned human dreams into sacred texts and created an industry out of their interpretation. That so furtive and repellent a creature experiences dream states just as we do confirms what many of us have long feared— that rats share far more with us than we want to admit. So we wondered: Just how rich might a rat dream be? We asked humorist and illustrator Bruce McCall to imagine a new scientific discipline: psychorodentology. Here, for your amusement, a look into that horrific future.— Reporting by Kathy A. Svitil
"At first," recalls one mystified researcher, "we thought we'd stuck the electrodes into his hippocampus backward or something." Why were the neuronal patterns traced in the dreams of Brownie, a mature laboratory rat, the virtual opposite of those detected during his waking hours? Then came a stunning revelation: Brownie, a living scientific punching bag, was determined to turn the tables on his keepers. "He was having revenge dreams," a respected psychorodentologist explains. "In Brownie's secret dreamland, he was a rat in a lab coat forcing hapless humans to perform stupid stunts in the name of science. He was dreaming up some wacky new experiment every night." Thanks to Brownie, a new pathology has been entered into the lexicon of rodent diagnostics: maze rage.
762-A, on Drugs
Number 762-A was an otherwise archetypal rat with an all-too-familiar case history: born in a slum, abandoned by his parents, existing on scraps, a social misfit forever on the run. Yet 762-A's symptoms fascinated the rat-dream research community. Avoiding the pack, he was a nonjoiner, a loner, a recluse. His personal hygiene fell far below even rat standards. Lethargic, no appetite— what ailed 762-A? Three nights of dream tracking yielded dramatic clues. In one dream, 762-A was panicked at finding himself alone in pitch darkness. In another, he was starving but recoiled at the sight of food alive with maggots. And in a dream that induced such stark terror it made his electrodes pop off, 762-A slithered down a sewer pipe and was confronted by— a mouse. Here was a rodent in despair. Fortunately, the new antidepressant Ratolin has turned the tide. Today 762-A shows every sign of leaving his depression behind. His dreams teem with sexual fantasies, Dumpster orgies, and a scenario in which he races fellow rats up a side of the World Trade Center— and wins.
FranÇois's Sense of Tastefulness
Dream research on François, a kitchen rat who lives in a prestigious Parisian seafood restaurant, has shocked rodentologists everywhere by suggesting that genus Rattus can decipher human language. Night after night, the messages from François's hippocampus translated into the same dream: eating, eating, eating. But only heaping bowls of ratatouille.
"He could as easily have been dreaming of eating the lobster, the sole, the tender baby octopus," reasons an eminent French analyst. "Mais non, only the ratatouille." Could it have been that this denizen of the underworld was responding to a verbal cue? "François hears thousands of words, the garçons ordering scores of different dishes every night," says the analyst, "but he has learned to distinguish words, one from the other. He comes to think, by the sound of the word, that only one dish must be made for him— ratatouille!"
Of course, when actually presented with his first bowl of ratatouille, François sopped up a mouthful and promptly spit it out. Clinical postscript: François has never dreamed of ratatouille since.
Eve's Nights of Splendor
The dream life of this female white rat, plucked from her nest in the moth-eaten fire curtain of a decrepit Broadway theater, has yielded an astonishing insight into the question of environment versus heredity. "A rat lives in a dump, eats leftovers, and rarely sees daylight," one therapist observes, "so her typical dream is pretty low-rent. But not this one, not Eve. She dreamed of her cage draped in pink satin, bouquets abounding. In her sleep Eve saw herself as the glamorous queen of the pack, lit always by a brilliant spotlight. Yet there were dark nights when she dreamed of diving headfirst into a bottle, devouring pawfuls of pills."
Eve's dreams are clear evidence that rat behavior is affected by environment. Immersed in a theatrical culture, Eve had absorbed it, identified with it, and in her dream life emulated it. This ordinary rat envisioned herself as no mere skulking, anonymous rodent but as a full-blown Broadway diva.
Rat research is still in its infancy, but researchers are already broadening their scope in search of further insights. Are rat dreams more Jungian than Freudian? Would an eclectic approach make more sense? Can therapy truly make a difference? Will psychopharmacology provide the answer? Balderdash, scoffs the rational human. But will it be the rats that have the last laugh?