THE ADOLESCENT BRAIN

WHILE early childhood has long been recognised as an important time for brain development, it’s now known that our brain keeps developing during puberty and adolescence. In particular, our prefrontal cortex, which is important for executive functions like emotional control, shows important changes at this time.

One example of this change is in “myelination”. Myelin is a fatty substance that surrounds the communication cables (axons) of neurons. This acts as a form of insulation, helping messages travel along the axons between different parts of the brain; the myelin forms the brain’s white matter. Although the axons in sensory and motor brain regions are fully coated in myelin by adolescence, the same is not true for the prefrontal cortex – it’s still developing. Without this insulating layer, the adolescent prefrontal cortex doesn’t communicate as well with other parts of the brain as it does in adults. How do we know this? Because of MRI technology, which lets us see the myelin-covered axons in the brain.

Another change taking place in the adolescent brain occurs at its synapses (connections between neurons). In the first few months of life, our brains makes lots of synapses, until we end up with many more than we’ll eventually have as adults. But, in our prefrontal cortex, it seems that this happens a second time. As we hit puberty, corresponding with a turbulent time of growth in the rest of the body, there is another wave of synaptic proliferation in the brain. As we move through adolescence, these connections are again pruned back and reorganised. This pruning makes the existing connections more efficient, so it’s essential to cognitive processes like self-regulation and “executive functions” like planning, decision making, organisation and emotional regulation.

SOURCE: QUEENSLAND BRAIN INSTITUTE AND THE AUSTRALIAN ACADEMY OF SCIENCE