The main models explored above are intended to cover some of the most central and important aspects of executive function, but this is a very large space and there are many important phenomena that we unfortunately cannot cover (though we plan to expand the scope of what is covered in future revisions, with optional models covering various of the following topics).
For many people, particularly in an academic setting, the first things that may come to mind if asked to name some higher-level cognitive functions might be things like: learning and/or using formal mathematics (like calculus or statistics); or, perhaps, the use of careful logical reasoning to make a major decision. But, in addition to these highly formalized domains, there are many other day-to-day, but none the less important, mental activities that also involve a highly sophisticated level of processing, activities like: planning one's day or a work project, or; resisting the temptation to have dessert when you are trying to lose ten pounds before bathing suit season, or; counting cards in working memory while playing blackjack. All these kinds of mental activities are now known to rely upon the frontal cortex and related structures for their optimal expression. Here is a list of some major categories of distinctive executive functions:
- Highly structured cognitive activities, often involving formal symbol systems -- Mental activities like learning and/or using mathematics, formal logic, computer programming, creative and/or non-fiction writing, and structured, rational decision-making. All of these require temporally-extended maintenance of task-relevant information, especially of a highly abstract, symbolic nature. The role of language in these and many other executive functions is a very important aspect -- language provides a highly flexible mental currency for active maintenance and control over behavior -- by remembering specific words or phrases, we can remind ourselves of what we want to achieve, or what we have derived in an initial processing step, etc.
- Control over encoding and retrieval of episodic information in the hippocampus -- it is highly likely that the hippocampus and PFC/BG systems interact significantly in many forms of executive function, with the rapid learning abilities of the hippocampus complementing the transient, flexible active maintenance properties of the PFC. If the PFC gets distracted, the information is typically gone forever, but the hippocampus can encode and retrieve information in terms of long-lasting synaptic changes. Often, it may be more efficient to use this hippocampal encoding and retrieval instead of persistent active maintenance of information in PFC.