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The Activation Synthesis Theory of Dreaming –Hobson & McCarley (1988)In the 1970s, J. Allan Hobson and Robert W. McCarleydeveloped the activation synthesis theory of dreaming. This theory states that dreams are produced by random stimuli from the pons. The forebrain, the "thinking" part of the brain, receives these stimuli and then makes up stories to make sense of them. These stories are what we call dreams.According to the activation-synthesis theory, dreams are merely the brain's reaction to random biological processes that occur during sleep.Various parts of the brain -in particular the pons, part of the brain stem -continue to function and produce stimuli during sleep and REM sleep in particular. The brain then takes these internal stimuli and attempts to make some sort of sense of them. To do this it uses other random stimuli and memories, especially those easily accessible in the short-term memory.Random BrainwavesFor example, the randomly produced stimuli might resemble those produced when running. The sleeper's mind could then interpret those stimuli as a dream of running. If, in addition, they had earlier thatday been startled by a cat then the brain might latch on to that memory and produce a dream of being chased by a lion. Thus cortical attempts to explain random signals from the lower brain produce a random dream with no deep or hidden meanings or purpose.As the pons continues to fire random stimuli at the forebrain, the latter constantly attempts to interpret them. This is why dreams sometimes shift so suddenly in content. The forebrain is attempting to respond to totally new random stimuli and needs to build a completely new situational model to incorporate them.The activation-synthesis hypothesis has the advantage that it renders dreams meaningless and removes any need to understand or interpret them. Some would argue that this is also its biggest disadvantage.We Dream Outside of REM SleepThe activation synthesis theory is based on the idea, which has been shared by many, that dreams are an aspect of REM sleep. Therefore, if REM sleep is caused by activity in the pons, then dreams are caused by activity in the pons.However, in 1962, cognitive psychologist David Foulkes performed a sleep study. In such studies, subjects are usually woken up at different ages of sleep and asked if they have been dreaming. However, instead of asking subjects if they had been dreaming, Foulkes asked, "What was passing through your mind?" Half of the subjects who were awakened during NREM sleep reported complex mental activities that could have been considered dreams.While the average NREM dream is less vivid than the average REM dream, between 5 and 30 percent of NREM dreams can't be distinguished from REM dreams. Considering that about three quarters of the time we spend sleeping is spent in the NREM stages, this means that about one quarter, at least, of vivid dreams take place during NREM sleep.Could some of Foulkes' subjects who claimed to have been dreaming vividly in NREM sleep really been dreaming during an earlier REM stage and been mistaken about when they dreamed? In many cases,
that would not have been possible. Foulkes found that subjects would report dreams even before they had entered the first stage of REM sleep.Later research has shown that if someone is awakened during the first few minutes of sleep, they will report a dream 50 to 70 percent of the time, and the dream will be no different from an REM dream, except for the length.People Who Don't Have REM Sleep Still Dream/People Who Don't Dream Still Have REM SleepAt the end of the 20th century, Solms studied records of cases in which people suffered damage to the pons and therefore lost most or all of their ability to experience REM sleep. He found 26 such cases. He found that only one of these people said that they had also stopped dreamingSolms also studied records of cases in which people stopped dreaming after suffering brain damage. There were 111 such cases. In all but one case, there was no damage at all to the pons. A completely different part of the brain was injured.Further studies have shown that in these cases, people still experience REM sleep, even though they no longer dream. To ensure that they haven't simply forgotten their dreams, patients have been awakened during REM sleep to check that they haven't been dreaming.Where Dreams are MadeSolms then performed a study of his own neurosurgical patients in hospitals in London and Johannesburg. For four years, he asked every patient if they had noticed any changes to their dreams after they had suffered brain damage. For a control group, he used patients who had been referred to him but had been found not to have any neurological damage.Patients reported four types of major changes to their dreams:Some patients stopped dreaming altogether.Some patients stopped seeing things in their dreamsSome patients started having recurring nightmaresSome patients began to confuse dreams and realityBy looking at where these patients' brains had been injured, Solms was able to find which parts of the brain have a part in the dreaming process.Dreams are Made in the ForebrainSolms found thatwhile REM sleep is produced by the pons in the brainstem, dreams are produced in two different areas of the forebrain.One of these areas is in a part of the frontal lobes just above the eyes. This area contains a pathway through which a chemical called dopamine travels from the middle of the brain to the higher parts of the brain. When someone suffers damage to the dopamine pathway, they continue to have REM sleep, but they stop dreaming.In the 1940s and 1950s, a study was done of over 300 people who hadundergone frontal lobotomies. It was found that these people tended to have very few or almost no dreams.Drugs such as L-Dopa, which stimulate the dopamine pathway, cause people to have vivid dreams. Drugs such as haloperidol, which suppress the dopaminepathway, can cause frequent, excessively vivid dreams to stop.