I’ve long been interested in neuroscience so I was keen to see the programme on BBC 4 on Thursday night called The Brain: What Makes Me. It featured American neuroscientist David Eagleman demonstrating how life shapes our brains, whilst at the same time our brains are shaping our lives. It’s essentially another take on the nature/nurture debate, but the advent of modern electronic imaging now means that it is possible to actually show changes in the brain that occur as a result of life experiences as well as disease processes.
Unlike animals, humans are able to adapt to different environments that might, on the surface, appear hostile to human life (think deserts and the North and South poles). Our brains help us adapt in order to survive. When we are born our brains are unfinished. As Eagleman says, “It takes life to tune up our brains.” In the first two years of a child’s life the brain whizzes frantically, making millions of connections between cells, but after this time the growth in connections halts and the brain starts pruning, in order to focus on a smaller number of links. If those initial connections have not been made because of severe deprivation of care and stimulation in early years, then long-term damage is almost inevitable as in the case of the Romanian orphans. If these terribly deprived children were adopted before they were two, they mostly recovered normal brain structure but those adopted later mostly have long-term problems, even when they have been cared for in loving families for many years.
In teen years the brain undergoes a transformation as it adapts to floods of hormones. Social emotions go into overdrive and there is often poor impulse control and greater risk taking. By age 25 this has mostly calmed down.
Until fairly recently it was thought that adult brains were fairly fixed entities but research has now shown that what neuroscientists refer to as plasticity, remains. Change is not only possible but it happens all the time. Eagleman cites London taxi drivers who spend about four years learning the streets of London (doing The Knowledge) and whose brains are changed by the experience. He also, perhaps more controversially, asserts that “Who you are or who you can be is a work in progress. Our identity is constantly changing.”
This makes me think about the differences between personality and identity. Maybe our fundamental personality (our approach to life and how we deal with it) is more laid down by genetics and heredity but who we are is much more fluid and open to the many influences of our upbringing, education and life experiences. Changes in temperament, personality and ‘who we are’ are also vulnerable to diseases such as Parkinsons or a brain tumour and general ageing and deterioration that shapes our neural networks.
I personally feel very encouraged by what Eagleman says about the brain being a work in progress and feel that I recognise this from my own life where I certainly feel a very different person to the one I was growing up… and well into adult years. In fact I feel I have ‘grown into myself’ if you like, feeling comfortable these days with who I am, but also aware of the changes that are to come. I know that the whole issue of identity can be an intensely emotional one for donor conceived people, some of whom strongly believe that they cannot know who they really are until they know who they are genetically connected to. I absolutely recognise that this is a very complex area. Genetic connections are important but I would claim we are more likely to define ourselves as we get older by how others see us, by the relationships we have, some of which will be genetic and others not and what we have achieved in life. Can those people we are genetically connected to but have never met really have such a profound influence when it is clear that both epigenetics (potentially triggering some genes to shut down and bringing others into play both before and after birth) and the impact of life experience on the brain play such important roles in shaping what the blueprint of DNA becomes, uniquely – ME, YOU… US.