Most people don't know that Sigmund Freud was a frustrated neurologist. Before he abandoned himself to abstraction, the father of psychoanalysis was a practicing physician, intent on developing "a neural model of behavior." (Kandel Interview) But Freud found neuroscience too blunt a tool, in the early twentieth century, to serve his purposes.
If brain science had been further along at the turn of the century, we might have been spared the Oedipus Complex and the concept of penis envy. But we may also have missed out on his theory that dreams are a form of wish fulfillment--a hypothesis that still holds sway among many scientists and psychologists. (The Interpretation of Dreams)
Over the past 50 odd years, many scientists have tried to debunk Freud's theory, which initially seemed far too fuzzy-headed to qualify as real science. Most were unsuccessful. But one alternative theory did gain credence.
In the 1970s, sleep specialist J. Allen Hobson presented compelling evidence that Freud's theory of dreaming was itself a form of wish fulfillment. According to Hobson, Freud had read far too much into dreaming. He'd constructed a theory to reflect his belief that dreams had meaning. But Hobson's research suggested that nighttime hallucinations were the nothing more than the brain's attempt to turn a set of random stimuli into a cohesive narrative. And, unlike Freud, Hobson's theory was supported by credible biological evidence.
By the '70s, neurologists believed that the pons, a primitive brain region located on the brain stem, was the seat of dreaming. Patients who had damage in the pons never achieved REM sleep--the sleep cycle then believed to produce dreams. It was also widely believed that dreaming didn't involve the brain's intellectual and emotional regions.
Hobson wasn't satisfied with these findings. Given the emotional intensity of many dreams, he found it hard to accept that the brain's emotional centers didn't contribute to the dream experience.
Through a series of experiments, Hobson revealed that when REM sleep was triggered, it activated the production of a neurotransmitter called acetylcholine. He demonstrated that the pons used acetylcholine during REM to "send impulses to various brain regions . . . including the limbic system, the emotional center of the brain."" Hobson's theory, known as the reciprocal-interaction model, posited that "the sleeping brain tries to do with these [arbitrary] signals exactly what it does in the waking state with sensory inputs: make sense of them." (Sweet Dreams Are Made of This)
Hobson's findings were persuasive and many scientists adopted his theory wholesale. That is, until Mark Solms, a member of NYU's Psychoanalytic Association, proposed an alternative theory. Like Hobson, Solms believed that the pons triggered REM sleep, but he contended "the origin of dream content lay in the highest-level brain regions." And he also had scientific evidence to back up his claim.
If, as Hobson posited, the pons and REM sleep were wholly responsible for dreaming, then people with damaged pons' would never dream. Solms demonstrated that this wasn't the case. He studied 26 people who could no longer achieve REM, due to brain lesions on the pons, and found that only one member of the group had completely lost the ability to dream. Solms went on to identify "two areas [in the brain] in which damage could cause complete loss of the dream experience": the white matter of the frontal lobes and the occipitotemporoparietal cortex. Neither were anywhere near the pons.
Solms research proved that people dream even when they aren't experiencing REM sleep. But, more importantly, it suggested that dream content originates in the brain regions associated with rational thought. In other words, Solms agrees with Freud. Dream imagery is not random, according to Solms. It is a form of unconscious thought.
Today, neuroscientists, psychologists and psychiatrists are split into two camps: Hobson supporters and the Solms advocates. The debate rages on and no one has come out the clear winner. But I was interested to read of a recent study about near death experiences that seems to support Solms' theory.
New@Nature.com recently published an article detailing the findings of neurophysiologist Kevin Nelson of the University of Kentucky, Lexington. Nelson conducted a study of 55 people who reported having "white light" experiences as they lay close to death. Of these 55, 33 (or 60 percent) claimed that they'd had "at least one incident where they felt sleep and wakefulness blurred together." Put simply, Nelson's research suggests that near death experiences could be a form of dreaming.
If this proves to be the case, it buttresses Solms' belief that dreams "can be shaped by hidden emotions or motives." Who among us wouldn't wish to save ourselves the agony of experiencing the final moments of consciousness? It makes perfect sense that the brain would manufacture a pleasant dream landscape to blunt the pain and fear of death. This is, in a sense, the ultimate in wish fulfillment.
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