The controllosphere: The neural origin of cognitive effort.

Why do some mental activities feel harder than others? The answer to this question is surprisingly controversial. Current theories propose that cognitive effort affords a computational benefit, such as instigating a switch from an activity with low reward value to a different activity with higher reward value. By contrast, in this article, I relate cognitive effort to the fact that brain neuroanatomy and neurophysiology render some neural states more energy-efficient than others. I introduce the concept of the "controllosphere," an energy-inefficient region of neural state space associated with high control, which surrounds the better known "intrinsic manifold," an energy-efficient subspace associated with low control. Integration of control-theoretic principles with classic neurocomputational models of cognitive control suggests that dorsolateral prefrontal cortex (DLPFC) implements a