The human brain, and its infinite biological functions, has fascinated scientists for centuries, and holds the answers to countless questions about the nature of life. It is the most impressive organ in the animal world, and over thousands of years has determined the very survival of the human species, all thanks to the evolution of one uniquely human trait: consciousness.
Research into consciousness has made great strides over recent years, and the most eye-opening studies are currently being conducted in the field of neuroscience. David Eagleman is a leading neuroscientist and an influential scientific populariser, and he believes that the brain’s most outstanding quality is its ability to adapt. The plasticity of the brain means that human beings are greatly influenced by their environment, including the way we think, feel, dream, and imagine.
Our biological growth is the perfect example of this process. From the moment we are born, and until the age of two, human brain cells begin to form connections to each other at a truly astonishing rate, creating millions of connections per second. Over time, these connections, which are called synapses, are ‘pruned’ or eliminated, in order to make the overall system more efficient and functional. Adults, in fact, only have half of their original synapses. After the ‘pruning’, we are left with a complex network of electro-chemical impulses, which are selected according to what we need, in order to be able to cope with the outside world. The emotional care we receive during our early years is crucial, because it helps to create an environment that supports our growth, allowing us to meet the necessary stages of development and to develop adequate physiological responses.
The next important phase is adolescence, because this is when hormones come into play, which contribute to reinforcing our sense of self and creating a deeper form of awareness. The reason for this change lies in the area of the brain called the median prefrontal cortex, which develops during adolescence, and is activated in particularly emotional situations. Adolescents therefore typically crave social interaction and tend to take more risks, because they are driven by an innate emotional hypersensitivity, which encourages them to seek biological rewards through interpersonal recognition.
Neurologically speaking, adulthood begins at approximately twenty-five years old, when the cellular tissue is fully formed. Everything that survived the pruning process, however, is still capable of changing and adapting, on the simple basis of our experiences. This process of adaptation sometimes has an important impact in our brain. For example, research conducted on London taxi drivers, who are required to memorise every street, landmark, and route around the city, showed that their hippocampus, the area of the brain responsible for spatial memory, is more highly developed than usual, and that this is a result of the enormous amount of information they need to remember.