[Emergence and brain development of executive functions].

Development of executive functions (EF) during childhood and adolescence is closely related to frontal lobe maturation and its connections with other cortical and subcortical structures. The main maturative processes are myelination and synaptic pruning, both of which work on the brain following a hierarchical model. Different studies agree with the fact that EF emerge at the age of 6 years. However, these studies have used complex neuropsychological tests, which require appropriate functioning of several cognitive functions. This is why differential development of different EF components cannot be observed. To do so, other studies have designed simpler tasks, which only need active maintenance of information and inhibition, both basic functions for the appropriate execution of more complex EF tasks. When these simple tasks are used, an early appearance of EF can already be noticed at the age of 12 months, and there are important advances between the third and fifth year. Consequently, the idea of the frontal lobe being "functionally silent" until adolescence seems definitively discarded.