Start with the cortex and work our way down. Unfortunately, not really enough data to make comparative analysis. Associated with behavioral specializations. E.g. Brocca s area in human cortex. Primary motor cortex MI control of voluntary movement.
Neurons are directionally selective.
May fire under a range of direction of movements, but has a best movement. Thus movements are coded by groups of neurons. Each cell carries only partial information. Connects to higher order sensory fields. Corticospinal tract monosynaptic on some alpha motoneurons controlling digit tips, most are polysynaptic lesions to MI the inability or lack of use of half of body.