As we grow, our brain continues to develop through adolescence. We know that while different areas in the brain are associated with various abilities, it is with the frontal lobes, located in the newest, outer layer of the brain and which Dr. Elkhonon Goldberg, a leading expert in the field, describes as the instrument, and the agent of control within the central nervous system (CNS), that executive function is most often linked.
Executive function can be conceptualized from a variety of perspectives. Generally there is agreement that executive function includes some degree of cognitive abilities that assists us in engaging in behaviors that are directed toward achieving complex goals. In addition, adaptability to changes and demands within the environment is critical. Other definitions might include (1) the ability to anticipate and plan outcomes, (2) the ability to monitor one’s own behavior for desirability or suitability in a given situation, (3) the ability to determine effectiveness of how we solve problems, and (4) the ability to allocate attention.
The frontal lobes, or prefrontal cortex, play a specialized role in orchestrating other brain areas. However, to do so, the prefrontal cortex receives input from many other cortical areas. This synergistic relationship suggests that the prefrontal cortex is dependent on other brain regions for input. To operate to the optimum, the information shared between brain regions must be of good quality.
For many decades, early neuropsychology thought that prefrontal functions did not emerge until late childhood or early adolescence. Due to the prevalence of this thinking, our understanding of the development of executive functions is more recent than our understanding of other cortical areas. A number of various methodological approaches have been used to add to our understanding of how the frontal lobes, hence executive functions, develop. Recent evidence linking CNS maturation and cognitive development provides a framework for understanding brain-behavior relationships through childhood. The frontal lobe seems to develop in growth spurts. Current research in this area suggests that the basic executive functions develop early in life and follow a stepwise progression to maturity in adulthood. Improvement in executive functions appears to be orderly coinciding with these growth spurts. Some experts place the first of these growth spurts in the frontal regions between birth and 2 years of age. A second growth spurt occurs between 6 and 7 years of age. Welsh asserts through his research that the ability to resist distraction matures at around age 6. Various researchers identify that additional growth spurts occur at about 10 to 12 years of age, followed by spurts in the later teen years.
As children grow and develop, they are better able to regulate their behavior. The ability to plan, set goals, and respond to their environment becomes the basis for behavioral choices that are mediated or regulated by the prefrontal cortex. We may think of executive function, then, as the component that directs attention, monitors and/or regulates activity, and coordinates and integrates information and activity. Goldberg recognizes that the capacity for volitional control over one’s actions is not innate, but it emerges gradually through development (Goldberg, 2001).
Let us consider that the difference between the time knowledge starts versus knowledge-based action or behavior appears to be an expression of the development of prefrontal executive function. As a result of her experiments, Baillargeon and her colleagues have demonstrated that infants have knowledge of object permanence—the knowledge that an object continues to exist even though it is no longer present in the immediate environment—months before they are able to utilize that knowledge to guide goal-directed search behavior. Almost certainly the maturation of executive and other systems in the prefrontal cortex between 4 and 9 months of age is necessary for this goal-directed behavior to occur.
Maturation of executive functions is crucial to psychological adaptation and adjustment across the life span. Dealing with the inherent ambiguity is among the chief functions of the frontal lobes. As the individual develops, executive planning involves complicated, means-end problem solving to achieve a behavioral goal and the ability to delay a response. Executive processes required for success in an interactive social environment are much more complex and wrought with ambiguity than the executive processes required when individuals have only themselves to consider.
References:
- American Academy of Neurology, http://www.neurology.org/ American Psychological Association–Division 40 (Clinical Neuropsychology), http://www.div40.org/
- Anderson, V., Northam, , Hendy, J., & Wrennal, J. (2001). Developmental neuropsychology: A clinical approach. London: Psychology
- Goldberg, (2001). The executive brain. New York: Oxford University Press.
- Kolb, , & Whishaw, I. Q. (2003). Fundamental of human neuropsychology. New York: Worth.
- Wedding, , Horton, A. M., Jr., & Webster, D. (Eds.). (1986). Neuropsychology handbook: Behavioral and clinical perspectives. New York: Springer.
- Zillmer, A., & Spiers, M. V. (2001). Principles of neuropsychology. Belmont, CA: Wadsworth.