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Myths about the brain | Deconstructing preconceived ideas for a better understanding

  • by Loriane Latapie

The brain, a fascinating and complex organ, is often surrounded by myths that can influence our perception of ourselves and others. Let’s demystify a few preconceived ideas about how the brain works.

Contents:
Myth 1: We only use 10% of our brains
Myth 2: Adult brains can’t change
Myth 3: Younger brains are smarter than older brains
Myth 4: Intelligence is determined solely by genetics
Myth 5: Men and women have fundamentally different brains
Myth 6: “Left brain” VS “Right brain”

Myth 1: We only use 10% of our brains

Reality: All parts of the brain have a function and are active at different times.

Neuroscience research shows that the whole brain is active, even when we’re at rest. Brain imaging techniques, such as functional MRI, show that different areas of the brain are involved in a multitude of tasks, from solving a problem to dreaming or recalling a memory. The idea that we only use 10% of our brain is a myth popularized by Hollywood culture(Lucy, Limitless). In reality, neuroscience shows that the whole brain is active, even at rest, and consumes around 20% of the body’s energy.

This myth may have originated with the psychologist William James, the originator of the “energy reserve” theory, or with the neurosurgeon Wilder Penfield, whose research showed that 10% of cerebral stimuli produced a visible response, but did not mean that the rest were inactive. Another theory for the emergence of this myth stems from scientific confusion following the discovery of the existence of glial cells, which fill the spaces left by neurons and protect the nerve connections between them. At the time of their discovery, we thought they made up 90% of the brain (when in fact we were closer to 50%). Unaware of their actual functions, some speculated that only 10% of our brains were actually being used.

In reality, the brain is in perpetual activity, whether processing memories, regulating emotions or performing vital functions. Even in blind people, brain areas dedicated to vision reorganize themselves for other functions, illustrating the brain’s plasticity. Rather than trying to “unlock” a hidden potential, it’s better to stimulate and maintain our abilities.

Myth 2: Adult brains can’t change

Reality: The brain is capable of remodeling itself and establishing new connections throughout life.

The brain is capable of remodeling itself and establishing new connections throughout life, a process known as neuroplasticity. This capacity for modification is particularly marked during learning, but also in response to injury. Studies have shown that adults can not only learn new skills, but also recover lost functions after a stroke, thanks to brain plasticity. However, this capacity for transformation is modulated by a variety of factors, including age, type of injury and the region of the brain affected.

Neuroplasticity is not a uniform phenomenon throughout brain development. In fact, there are critical windows when certain brain regions are more or less responsive to experience. For example, research has shown that if the motor cortex is damaged during early adolescence, results are less favorable than when it is injured in late adolescence. However, this is not the case for all brain regions: the prefrontal cortex, for example, shows the opposite dynamic. This suggests that each brain region may have sensitive periods, or critical windows, where it is more susceptible to changes due to experience. This plasticity, also known as metaplasticity, implies that experiences throughout life do not act as isolated events, but interact with each other to modulate both behavior and brain structure.

Moreover, plastic changes at the synaptic level, while important, are only one aspect of brain reorganization. Increasing research suggests that these changes also occur at the level of gene expression, with hundreds of genes potentially involved in the brain’s response to experience and trauma.

Myth 3: Young brains are smarter than old brains

Reality: Older brains can excel in areas such as wisdom, experience and decision-making.

Although the speed of information processing may diminish with age, older people are able to make decisions based on prior knowledge accumulated throughout their lives. This expertise often enables them to tackle complex problems with superior discernment and depth of analysis, compensating for some of the cognitive declines observed in areas such as memory, language or executive function. Their semantic memory (memory for facts) is superior to that of younger people.

Neurological research shows declines in gray and white matter volume, as well as changes in neurotransmitter levels, but these factors do not mask the benefits of cognitive maturity. These changes still allow us to maintain a good level of functioning and autonomy.

Myth 4: Intelligence is determined solely by genetics

Reality: Many environmental, cultural and educational factors influence the development of intelligence.

Twin studies show that, while genetics play a role, the learning environment, social interactions and life experiences are also crucial in the development of cognitive abilities. In childhood, 20% of intelligence is thought to derive from hereditary factors, compared with 80% in adulthood. These results suggest that the environment is crucial to intellectual development in childhood, but that, later in life, the influence of genes becomes more important.

Myth 5: Men and women have fundamentally different brains

Reality: Although there are structural differences, cognitive abilities are often more similar than we think.

Gender stereotypes often associated with brain differences can affect perceptions of intellectual ability. Studies show that, although there are variations, there is considerable overlap between the cognitive abilities of men and women. Subtle differences exist: for example, in the DMN (default-mode network), which defines how our brains behave when we do nothing. While women seem more inclined to self-reflection, emotion management or retrieving memories of events linked to them, men are more involved in association processes or reward-based learning. These differences are not in the structure of the brain, but in how the different regions interact.

Myth 6: Left brain VS right brain

Reality: The brain functions as an integrated whole, not as two opposing hemispheres.

The idea that some people are “left brain” (logical, analytical) and others “right brain” (creative, intuitive) is a myth. Although each hemisphere has its own specializations – language being generally associated with the left hemisphere and spatial perception with the right – neuroscience shows that they always work in collaboration.

For example, Broca’s and Wernicke’s areas, located on the left, are crucial for language production and comprehension, but the right hemisphere is also involved in the interpretation of nuance and figurative meaning. Similarly, memory and emotions, managed by the limbic system, involve structures located in both hemispheres.

The origin of the myth goes back to 1960s studies on patients with “split” brains, whose corpus callosum (the connection between the two hemispheres) had been severed. Although this research revealed certain hemispheric specializations, it does not mean that one hemisphere globally dominates a person’s thinking.

Modern brain imaging confirms that cognitive functions rely on interconnected networks rather than just one side of the brain. Even logical or creative tasks mobilize both hemispheres, showing that human thought is far more flexible and adaptive than this myth suggests.

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