Environment and Brain
Dr. Vivek H. Ramanandi (PT, PhD)
Assistant Professor, SRMS (Physiotherapy), CHS, University of Nizwa.
“The thrill of life is not about who we are but about who we are in the process of becoming.”
David Eaglemen
The human brain consists of 86 billion neurons, the building blocks of a complex, dynamically evolving network of more than 0.2 quadrillion connections. The brain is a dynamic system that continually adapts its circuitry to match the demands of the environment and the body's capabilities. Nature has followed an unconventional approach while designing the human brain: “Don’t build inflexible hardware; build a system which is adaptable to the world around it.”
The neurons within this system constantly compete with one another and modify their structural and functional connections based on a person's experiences and goals throughout their lifetime. For example, if a writer drops his career to become a footballer, his motor cortex will show enlargement of the area associated with leg movements and strength; if he becomes a perfumer, his brain areas related to perception and interpretation of smell will enlarge. The brain gradually adapts itself to reflect the challenges and goals it faces and molds its resources to match the needs of the circumstances. This ability of the human brain to adapt and mold itself was called “Plasticity” by the American psychologist William James in 1890.
William James (January 11, 1842 - August 26, 1910)
The concept of neuroplasticity holds that the human brain is only partially pre-programmed at birth, allowing it to adjust in response to demand and exposure. As infants, we are usually born with specific innate abilities, or we can say basic programming, such as the ability to mimic an adult, which requires translating visual input into a motor feat. This introductory programming can be attributed to the genetic hardwiring of human beings. In 1874, Charles Darwin examined the structure and function of the brains of wild hares and compared them with those of domestic rabbits, surprisingly finding that wild hares had larger brains. He attributed this difference to the fact that in the wilderness, the hares needed more use of their wits and senses to survive in comparison to the rabbits in a domestic environment.
During the 1960s, researchers began exploring the effects of different types of experience on the development of brain structure in rats. Richness or deprivation of the environment around the rats altered the brain structure in significant ways. The rats raised in an enriched environment, e.g., where the surroundings are packed with toys, running wheels, levers, etc., showed better brain development, as evidenced by better performance on various tasks and long, lush dendrites found at autopsy. Rats raised in a deprived environment, e.g., an empty, solitary cage, showed poor performance on tasks and had shrunken neurons with short dendrites.
Development of Dendritic Network in Enriched
versus Standard Environment
Similar experiments in birds, monkeys, and other mammals showed that context-specific exposure plays a role in brain development. In the 1990s, California-based researchers autopsied the brains of those who completed high school education and compared them with those who had a college education. They found that college-educated people showed elaborate dendritic connections in areas responsible for language comprehension.
The fine structure of the brain reflects the environment to which a person is exposed and depends on culture, economic conditions, family structures, and a person's primary genetic makeup. The lack of numbers and genetic variation within the human race creates a need for a strategy to survive in this ever-evolving world. The approach nature adopted for the human brain is: “Build incompletely and let the world experience refine.” At birth, the human brain is remarkably unfinished in terms of functionality, and interaction with the surrounding environment shapes it as necessary. The influence of pre-specified genetic factors largely depends on receiving a vast set of experiences, including social interactions, conversations, play, exposure to the world, and the rest of the multi-coloured landscape of everyday human life.
Not only the amount but also the nature of exposure significantly impacts brain function development. Negative impacts of poor brain-shaping experiences during childhood can be detrimental to brain structure and function. A girl named Danielle, who was raised as a feral child, was discovered in 2005 in Florida, USA. She did not show any behaviours and expressions inherent to everyday human interactions, as she had missed the critical window of development where she was supposed to have exposure to human beings other than her mother, who kept her locked inside a dark closet for her entire childhood. She had never received any physical affection or engaged in everyday conversation beyond basic sustenance. She showed very little development in social aspects and had a poor prognosis because of her lack of exposure during the critical window of development. We can say that Mother Nature’s strategy of designing the brain depends upon proper world experience, and the lack of such knowledge can cause the brain to become malformed and pathological. It is like a tree that needs nutrient-rich soil to grow. Without the rich soil of social and sensory interaction, the tree of the brain can’t grow to its fullest potential.
“The magic of our brain lies not in its constituent elements, but in the way those elements unceasingly reweave themselves to form a dynamic, electric, living fabric.”
