This is why we dream, according to a neuroscientist
Dreams, that ancient enigma that has baffled humanity, continue to be the subject of intense research in the scientific world. Various theories have tried to shed light on its purpose, from emotion management to problem-solving.
A more recent proposal, put forward by Stanford University neuroscientist David Eagleman, suggests that dreams, especially during REM sleep, play a crucial role in protecting the brain’s visual cortex.
Eagleman’s theory, published on the site Scientific American is based on the highly adaptive capacity of the human brain, known as neuroplasticity. According to him, neurons compete for survival in a constantly changing brain territory.
This process of “life or death competition” drives the redistribution of brain resources, where sensory areas gain or lose territory based on experiences throughout life.
Eagleman illustrates this brain plasticity by referring to cases of children who have had half their brains removed due to health problems. Surprisingly the remaining brain reorganizes and takes over the functions of the missing sections, demonstrating the brain’s ability to adapt even in extreme situations.
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Rapid brain reorganization has also been observed in studies where subjects were blindfolded. Lotfi Merabet of Harvard Medical School and her colleagues showed that capturing an idle zone by other senses can begin in as little as 90 minutes. This adaptive capacity is essential to understand Eagleman’s theory of REM sleep as an active defense of the visual cortex.
The key is in REM sleep
REM sleep characterized by rapid eye activity plays a central role in this theory. Approximately 90 minutes after falling asleep, the individual enters the REM state.
During this period, neurons in the brainstem perform two crucial tasks: they paralyze the main muscles, preventing the sleeper from representing what is happening in the dream, and they send messages directly to the visual cortex, initiating the dreaming process.
Eagleman argues that the schedule adjusts to when the visual cortex needs to defend its territory. Brain scans of people who dream have revealed that most of the brain activity associated with REM sleep occurs within the visual cortex.
According to Eagleman, dreams act as a defense mechanism, preventing other sensory functions from co-opting this critical region of the brain.
The relationship between adaptability and REM sleep seems to be maintained in all species. Eagleman points out that Mother Nature throws human brains into the world “half-baked,” allowing experience to mold and shape them.
The less programmed the brain is at birth, the more able it is to adapt and learn from experience, although this comes with the need for longer REM sleep.
Although Eagleman’s theory has generated controversy, with critics pointing to cases such as blind mole rats still experiencing REM sleep, some experts are willing to consider his proposal. Deirdre Leigh Barrett, a psychologist at Harvard University, highlights the correlation between the intelligence of animals and the complexity of their brains.
However, the author is flexible in his approach and suggests that his theory can accommodate other explanations of dreams. He raises the possibility that REM sleep may serve multiple purposes in addition to protecting the visual cortex.
Compare dreams to a computer screen saver that activates every 90 minutes, preventing other functions from usurping the visual cortex and, in doing so, providing visual hallucinations that could influence daytime perception.
Although opinions differ in the scientific community, the study of dreams continues to be a fascinating and constantly evolving field. The quest to decipher the purpose and function of dreams remains a mystery challenging scientists to explore beyond the limits of science. neuroscience and psychology.
