Final answer:
The brain fully matures by the age of 25 years old, with the development involving neural blooming and synaptic pruning.
Step-by-step explanation:
Researchers now understand that the brain continues to mature into early adulthood. The process of brain development involves a period of neural blooming followed by synaptic pruning, which streamlines neural connections for more efficient functioning. According to studies, including those analyzing changes in white matter and gray matter, this maturation process continues through adolescence and into the early 20s. The development of the frontal lobes is particularly important, as this area is associated with complex cognitive functions, such as decision-making and impulse control.
In response to the question regarding brain maturity, it is known that the brain fully matures by the age of 25 years old. This is later than previously believed and suggests that adolescence extends into one's early 20s. While the brain does increase in complexity during adolescence, with an increase in the number of folds in the cerebral cortex, the size of the brain does not grow significantly after the age of six, where it has reached about 90% of its adult size. Myelination is another process that contributes to the brain's development during this time period.
The question of whether teenagers can be held fully responsible for their behavior, given that their brains are still developing, is a topic of ongoing debate. However, the science indicates that brain development, particularly the parts responsible for decision-making and impulse control, continues well into the early 20s.