Grand Unified Theories of the Brain Need Better Understanding of Behavior: The Two-Tiered Emergence of Function

Abstract Over the last few decades, neuroscience and various associated disciples have expanded enormously in terms of output, tools, methods, concepts, and large-scale projects. In spite of these developments, the principles underlying brain function and behavior are yet only partially understood. We claim that brain functioning requires the elucidation of the rules associated with all possible task realizations, rather than targeting the activity underlying a specific realization. A first step in that direction was taken by approaches focusing on dynamical structures underlying task performances, as exemplified by coordination dynamics. Its theoretical foundation owes much to Haken’s synergetics, which provides a formalism through which the degrees of freedom associated with high-dimensional systems may be effectively reduced to one or a few functional variables in the vicinity of phase transitions. The recent theoretical development of structured flows on manifolds (SFM) allows the employment to a potentially broader range of applications. Here we expand the SFM framework and propose that the emergent two-tiered fast–slow dynamics may be a basic mathematical organization underlying the architecture of brain and behavior dynamics. Finally, along a few examples, we illustrate how this framework allows for the incorporation of notions cardinal to ecological psychology.