When it comes to brain development, nature or nurture is one of science’s most enduring questions. In recent years, many of the most prominent names in neuroscience have researched the issue, with illuminating results. Our understanding of this area is gradually evolving to explain the full picture.
In the Past
Some thirty years ago, neuroscience believed that people are born with a certain number of neurons in their brain, which immediately begin to degenerate. This degeneration is then linear. Our brains slowly become less and less effective until we die. However, more recent research has suggested that this simply isn’t true.
Brain Plasticity
In 1998, a scientist called Fred Gage, working from the Laboratory of Genetics at the Salk Institute, showed that the brain continues to produce new nerve cells into adulthood. He also proved that, in mice, exercise increased the rate at which these new cells are created. This demonstrates that the whole system isn’t set by its initial genetic components. Instead, it is influenced by experience with the outside world. These discoveries led to an improved understanding of neuroplasticity. Neuroplasticity is the ability of the brain to grow, change, strengthen and eliminate new nerve cell connections throughout life. This discovery made scientists look at the question of nature or nurture in a whole new light.
Renowned neuroscientist, Blakemore explains, “Neurons can change their connectivity. They can change the strength of their connections. They can change the morphology of their connections. They can do it not necessarily in the early stages of life, although this is especially exaggerated, but probably throughout life. They respond to new environments and experiences.”
Scientists are increasingly convinced that the number and strength of connections in the brain changes continually. This depends on how often they are used. Genetic programming plays a key role in that we are initially born with certain ‘hard-wired’ connections. But the maintenance and strength of those connections changes over time. This is due to our experiences and the environment we encounter.
Therefore, in the question of nature or nurture in brain development, it isn’t a case of one or the other. The interplay between both nature, what we are born with, and nurture, what happens in our lives, is what determines brain development. Brains don’t develop normally without the initial genetic components. They also fail to develop normally in the absence of essential environmental input.
Genetic Disorders
Many common neurological and mental health conditions, including depression, schizophrenia, bipolar disorder, autism, Parkinson’s disease, multiple sclerosis and Alzheimer’s disease are incredibly complex genetic disorders. Science is revealing that these conditions are influenced by environmental factors. Studies are currently being conducted into the treatment of developmental disorders in humans. There’s a growing body of evidence that underlines the importance of the interplay between nature and nurture in this area. This involves a massive feedback loop between genetics, neurological structure, experience and disease.
Neuroscientist, Coyle, states, “You are three times more likely to die from a heart attack if you are depressed than if you are not… and depression has a huge impact on diabetes as well.” A step backward further demonstrates the interplay. It’s been discovered that people who experience significant trauma and stress in their lives are more likely to suffer from clinical depression. There’s also a huge variation in how trauma and stress affect us as individuals. Some people are more resilient than others.
Into the Future
Developments in imaging techniques and technologies, like channel rhodopsin ‘light switches’, enable us to see neural networks. We can then analyse how they react to external influences. This allows scientists to map the complex relationship between genetics versus experience. We can now see how both affect physical activity in the neurons within our brains.
Gene profiling and our technologies in genetic manipulation in animals also enable us to explore how genes manipulate our neural structures. These developments allow us to observe how environmental factors affect our behaviours, predispositions and health.
Today our scientists are convinced of the complex interaction between the elements of nature and nurture on our brains’ development and ability to function at an optimum level. In the future, we will discover further answers in this field. These answers will have important roles to play in the treatment and management of many conditions which negatively affect our lives.
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