Human Brain: Misnomer & Myths

There are a number of neuro-myths and misnomers floating around about the human brain. The aim of this mini series is to debunk and demystify some of those. The first one I want to discuss and expose is this idea of left and right brain and its associations.

Left & Right Brain

The two sides of the brain is used to symbolise two sides of human nature (logical & creative). One is disparaged (analytical brain) and the other (creative brain) is celebrated.

How many books and blogs have you read that gives you tips & techniques to enhance abilities of your right brain or left brain? There are even therapies available in the market to enhance abilities of your hemispheres 😳

Why Bilateral Symmetry?

Let's understand this idea anatomically. If you watch closely there is a certain symmetry to all animal bodies.

In a jelly fish, the symmetry is radial. We (humans) are bilaterally symmetrical. What that means is, you can draw a big line head to toe and divide the body into left and right.

Our bodies can move in left and right. To coordinate this movement our brains are structured in a symmetrical way. The right cerebral hemisphere receives sensory input from and directs movement on the left side of the body, while the left hemisphere governs corresponding functions for the right side. However our brain uses both sides to make a holistic picture of the world.

It is argued that our symmetry is rooted in evolution (survival). For example, it is safer to jump to the right side when a predator attacks from the left side. This survival advantage springs from a more complex nervous systems that gives us quicker reflexes.

Lateralisation

The most obvious manifestation of brain lateralisation is handedness. About 80-90% of human beings are right handed and they can control fine movements with their right hand compared to their left hand. The other 10-20% are left handed or ambidextrous. While the two sides of the brain are roughly equal in size, in most people, parts of the left hemisphere are slightly larger. This could account for the observation that lefties as a group tend to be more right brained (obviously).

The misconception of localised language functions (within one hemisphere) started cropping up when neurologists Broca and Wernicke saw issues with language for patients who had injuries to their left hemisphere (left temporal lobe). The idea of logical left hemisphere and emotional right hemisphere was stretched by author Louis Stevenson in his novel through the characters (Dr.Jekyll and Mr.Hyde). The imagination did not hold good scientifically when the brain was anatomically examined for patients who had their one hemisphere removed.

Whole brain

Scientists noticed one side of the brain did more work than the other. It had nothing to do with the personality but it was more systemic in nature. The hemispheres, after all, are not truly separate: communication between them is enabled by fibres, through which constant traffic of neural messages pass from side to side. The most prominent of these is the corpus collosum, but smaller commissural tracts connect the hemispheres as well.

Even the most complex mathematical equations need inspiration and creativity. Analytical and creative ability is what makes problem solving fun. We need the whole brain to solve problems. To understand language fully, requires both sides of the brain, working together.

🥂 to both left and right side of the brain!