H567/03 Section B Option 1 - Pre-adult brain development and risk

A developing network

Brain development continues through childhood and adolescence. It includes changes in the organisation and communication of neural networks, rather than simply growth in overall size. Different regions and connections change on different timetables, so there is no single moment when every function becomes mature.

Synaptic pruning reduces some neural connections while other connections are maintained and strengthened. This reorganises networks in relation to development and use; it does not mean that losing a connection automatically reduces intelligence. Myelination adds an insulating sheath around axons, supporting faster and more efficient transmission. Increasing coordination between regions can improve the integration of emotion, reward information and planning.

Prefrontal regions contribute to executive functions such as holding information in mind, inhibiting a response, planning ahead and considering competing consequences. These functions become more coordinated as relevant networks develop. Structural MRI can examine anatomical features; functional MRI measures changes in blood oxygenation associated with task activity. An fMRI signal is an indirect measure of neural activity, not a photograph of a thought or a direct measure of self-control.

The biological area connects development of these networks with behaviour. The cognitive area asks what information is represented and how a choice is evaluated. Together they explain why a person can understand a risk in a calm classroom yet make a different choice in an exciting situation.

Reward sensitivity and cognitive control

The ventral striatum is involved in reward processing and valuation. During adolescence, reward-related responses can become especially sensitive in some tasks and contexts. A valued outcome may be money, novelty, enjoyment or social approval. Greater sensitivity can encourage exploration and learning as well as potentially harmful choices.

Cognitive control networks, including prefrontal regions and their connections, support response inhibition and the coordination of longer-term goals. Their development generally extends over a more prolonged period than some changes in reward sensitivity. A developmental imbalance account proposes that strong motivation toward an immediate reward can outweigh less consistently recruited control, especially in emotionally arousing circumstances.

The two systems interact rather than acting as an isolated accelerator and brake. Adolescents have functioning control and can make considered choices. The explanation predicts context-dependent vulnerability, not constant inability to reason. A large expected benefit can also make a risk sensible: attempting a difficult audition may have a manageable cost and a valuable opportunity. Risk taking and poor decision making are therefore not interchangeable.