They talked about that in Jeff leads Numenta Research Meeting - Sep 4, 2019
L5 doesn’t necessarily represent motor commands like “throw ball”. It’s probably tied into sensory processing too. One example where motor/sensory are arbitrary distinctions is target selection. The superior colliculus (SC) produces saccadic eye movements and is sheet-like. In the fraction of a second before a saccade, there’s a bump of activity on part of the SC. That part of the SC corresponds to where the eye will move in visual space. Is the sheet a map of visual space or a map of motor commands? Maybe both.
Another thing which complicates motor vs. sensory is, where does sensory end and motor begin? The deeper layers of the SC send motor commands, whereas the superficial layers do not do so directly. V1 projects to the superficial layers of SC, whereas other regions project to deep layers. Does L5 of V1 send motor commands, or does it send visual information, such as potential saccadic targets? Is attention sensory or motor? Maybe L5 sends attention signals, like paying attention to throwing a ball.
The motor cortex probably has a lot of control over behavior, but most or all neocortical regions can produce behavior.
The cerebellum probably helps fine-tune behavior, which is important in nature but not so much for us. 3/4 of the brain’s neurons are tiny cells in the cerebellum. The circuitry is simpler than in the neocortex, but repeated a lot.