Leo (pseudonym), a 26-year-old promising experimental scientist, is a British Asian. He studied inorganic chemistry at a university in Scotland and was serving as a new professor at a prestigious technology research institute. One weekend holiday, he was involved in a car accident while driving with friends. A CT scan revealed bleeding and severe damage to the left parietal lobe of his brain. The parietal lobe is located in the upper part of the brain and is responsible for interpreting various sensory information, understanding language, and storing spatial memory.
He was on a ventilator for 25 days after the accident. After 39 days, when asked to speak, he was in a state of aphasia, unable to speak. He received intensive speech and physical therapy for three months. A neuropsychological evaluation was conducted 21 weeks after the accident. Clinical observations showed severe language impairment. He not only mispronounced words but also could not use them properly. Leo could not make any associations, and his dreaming had stopped.
Which part of the brain, when damaged, causes dreaming to stop? In other words, which part of the brain plays a crucial role in dreaming? According to a paper published by Allan Hobson in 1977, "dreams originate in the brainstem, the primitive brain, so the primary motivation for dreams is physiological rather than psychological, neutral in motivation, and without particular meaning." Hobson's view subsequently became the dominant theory in neuroscience.
A dramatic reversal of Hobson's theory began with a psychiatrist named Mark Solms. Solms' family lived in a German colony in Southwest Africa. Solms was inseparable from his older brother Lee, and they got along well. Then one day, his brother, who was six years old at the time, slipped and fell from a roof, injuring his brain. This incident completely and permanently changed Lee into a different person, and his younger brother Mark embarked on a lifelong journey of exploring brain science.
In the early 1980s, Solms was studying neuroscience in Johannesburg, South Africa. He learned a lot about the superficial mechanisms of the brain but could not find out anything about the deeper questions. Then, at a friend's recommendation, he attended a lecture on Freud's dream theory. He recalls that time: "Listening to Freud's theory about the brain functions underlying dreaming, I was literally mesmerized. Wishes, desires, intense emotional processing — all of it was related to our actual lives. It was something I had never heard in neuroscience lectures." He thought Hobson's 1977 paper was "overly assertive and unfairly diminished Freud's masterwork." However, he had no intention of proving the errors in Hobson's theory.
Solms studied patients with stroke, brain tumors, or brain injuries from accidents like his brother's at a neurosurgical hospital in London. Solms asked patients how their dreams had changed due to brain damage. The investigation was successful. One patient answered that they did not dream at all. That patient had parietal lobe damage. The parietal lobe is the area that combines various sensory information to create spatial orientation and mental imagery. Parietal lobe activity allows us to daydream about relaxing on a South Pacific beach or imagine the route to the bank.
Brain wave recordings showed these patients were still experiencing REM sleep. He hypothesized that the brainstem signals that initiate REM sleep were being transmitted as before, but the patients were not dreaming because the forebrain tissue that receives those signals and turns them into images was damaged. He encountered a group of patients with brainstem damage who reported dreaming. This was something that could never happen according to Hobson's dream generation theory.
Solms discovered another area where brain damage causes dreaming to stop. That area is the white matter located in the lower inner part of the forehead. In medical terminology, it is called the ventromesial frontal white matter. This area is the region that generates human motivation and corresponds to Freud's view that dreams express our most intimate wishes and fears. This area is also a pathway for the neurotransmitter dopamine. Hence, brain scientists also call this area the "reward" system or the "wanting" or "seeking" system — as in "I want that!"
In 1997, Solms published a paper stating that "the primary driving force that creates dreams is the seeking system (wishes) of the white matter, which is activated when pursuing primary desires." This was exactly 20 years after Hobson published his dream theory criticizing Freud.
Let us return to Leo's story, whose parietal lobe was severely damaged. Leo, whose dreaming had stopped after the accident, said "I had a dream" several months after receiving treatment. But at first, he could not remember what dream he had at all. Later, as his brain function recovered, he had ordinary dreams such as this: "I was walking down the street from my apartment in Soho (a district in London) when I met some Chinese people. There was one adult and three children. I walked a little further and met the mother of the same family I had just seen, along with a friend."
Leo could not make any associations from this dream and did not recognize the characters in the dream. What he realized was that he was normal in the dream.
The fact that he started dreaming again must be extremely important for him. For him, that dream is a sign of vitality regarding his inner life and psychological recovery. Now we all know the neuroscientific fact: whether we remember it or not, everyone with normal brain function dreams for an hour and a half to two hours during eight hours of sleep each day. And this means our brain is functioning normally.
