an integrative structure with many networks and subsystems, without a clear localization of each individual function. Each higher mental function—attention, memory, thinking, goal-setting, and control—depends on the interaction and coordination of multiple brain regions and constellations of neurons working in constant interaction, so that any disruption or developmental delay in one of these areas leads to a cascading effect of affecting the overall efficiency of mental functions. This concept emphasizes that developmental disorders or delays affect not one individual function, but a whole system. This makes understanding the brain as a functional system necessary to explain developmental difficulties and to develop effective assessment and treatment programs that take into account the interconnection of various neurological conditions and mental functions.