  We propose that the entirety of the prefrontal cortex can be seen as
fundamentally premotor in nature. By this, we mean that the prefrontal cortex
consists of an action abstraction hierarchy whose core function is the
potentiation and depotentiation of possible action plans at different levels of
granularity. We argue that the apex of the hierarchy should revolve around the
process of goal selection, which we posit is inherently a form of abstract
action optimization. Anatomical and functional evidence supports the idea that
this hierarchy originates on the orbital surface of the brain and extends
dorsally to motor cortex. Our view, therefore, positions the orbitofrontal
cortex as the central site for the optimization of goal selection policies, and
suggests that other proposed roles are aspects of this more general function.
We conclude by proposing that the dynamical systems approach, which works well
in motor systems, can be extended to the rest of prefrontal cortex. Our
proposed perspective will reframe outstanding questions, open up new areas of
inquiry, and will align theories of prefrontal function with evolutionary
principles.
