A number of psychotherapeutic theories exist regarding the function and meaning of dreams. Freud claimed that dreams express the fulfillment of unconscious forbidden instinctual wishes in disguised form. The consciously reported dream is the manifest content, and the unconscious meaning the latent content. Self psychologists believe dreams can reflect a patient's “self state.” Many therapists use dreams as projective tools, similar to a Rorschach or TAT card.
Neuroscientists debate about the function and meaning of dreams as well. Until recently, the reigning theory was that of J. Allan Hobson, who claimed that dreams are meaningless. During stage one of sleep, EEG recordings exhibit a characteristic pattern of intense bursts of high-frequency activity. At the same time there are rapid eye movements; thus this period is called “REM sleep.” During REM activity on EEG, if a person is awakened, he or she almost invariably reports a dream. Electrode probe recordings in cats have identified cells in the pons (a region deep within the brain stem) to be the source of REM activity. Neural projections from the pons stimulate other subcortical and cortical brain regions. This results in the phenomena associated with dreaming: eye movements, increased heart rate and respiratory rate, visuomotor activity, emotion, and the EEG pattern we know as REM. According to Hobson, dreams simply reflect this random electrical stimulation, and thus serve no function and have no intrinsic meaning.
At the American Association for the Advancement of Science meeting held in January 1999 in Anaheim, Calif., Allen Braun and Ramon Greenberg each presented their research contributions to the debate over the function and meaning of dreams. Both disagree with Hobson's narrow emphasis on the pons as the source of dreaming and Hobson's absolute rejection of any meaning to dreams.
PET scan studies performed by Braun during dreaming show increased activity in unimodal sensory cortex (vision, hearing, etc.), and “limbic” regions, including the amygdala, hippocampus and anterior cingulate, which are involved in emotion and memory. At the same time there is reduced activity in pre-frontal “executive” regions. According to Braun, the pattern of “high” sensory and limbic activity but “low” frontal explains the characteristics of dream sleep. Dreams contain highly vivid visual images and intense emotion, but highly improbable events with no consistent focus or coherent narrative.
For Braun, the findings of activity in higher cortical regions support the idea that dreams could be meaningful. He explains that visual, emotional, and memory systems are essentially released from inhibitory regulation. Since the frontal system — responsible for focal attention, rational thinking, and inhibiting impulses — is relatively inactive, inappropriate impulses and forgotten emotional memories may gain access to consciousness.
It is Greenberg's belief that frontal deactivation during dreaming is adaptive. With the “executive” functions turned off, different kinds of associative linkages can be formed and thus perhaps different kinds of solutions arrived at for problem solving. In addition, Greenberg maintains that REM sleep research indicates that the psychological events in dreaming and the physiological events in REM sleep represent different aspects of the brain's efforts to process events and learn from experience.
When rats are learning complicated tasks, REM activity increases. When they are deprived of REM sleep, their ability to learn complicated unfamiliar tasks is impaired. More relevant to human concerns is that rats raised in isolation during infancy are highly disordered in their adult behavior. Brief periods of socialization can prevent this. However, if rats are deprived of REM sleep, the positive effects of socialization are abolished.
In human subjects, REM activity increases when a person is acquiring a new skill such as a foreign language. REM sleep deprivation in humans impairs functioning in tasks that require creative thinking and problem solving. In more emotionally focused tasks, deprivation of REM sleep can impair normal subjects' ability to make meaningful connections between emotionally laden pictures (such as TAT cards) and emotional events in their own lives.
Patients who are under stress show an increase in REM activity; their REM activity decreases again when the stress is relieved. It is generally agreed that learning cognitive skills involves making associative neural links between current information and prior information. The studies suggest that REM activity is most likely involved in this process. Greenberg adds that the cortical and limbic activation during REM also suggest that REM activity is involved in associative learning from emotionally significant events, and that dreaming reflects brain efforts to cope with stressful situations.
Dreams are like a printout, showing the dreamer's struggles to make effective connections between past and present. Traumatic nightmares of PTSD replicate the trauma reflecting what Greenberg calls a “failed dream,” since no adaptation has occurred. As the trauma resolves, these nightmares diminish. Greenberg emphasizes that the actual dream images, i.e.., manifest content, are significant in and of themselves. They can represent current conflicts or aspects of earlier, childhood conflicts that are reactivated by the present conflict.
Regina Pally, M.D., a psychiatrist and psychoanalyst, is a member of the Los Angeles Psychoanalytic Institute.