01 - Spinal Locomotor Generator
I will use the notation [K&W:page number] for references to Kolb & Whishaw's Brain and Behavior.
On [K&W:358] the book says: "The frontal lobe of each hemisphere is responsible for planning and initiating sequences of behavior." This is the majority view and represents a "top down" understanding of human behavior. I will argue for a "bottom up" interpretation in which the frontal lobe plays an almost minor role in determining our behavior.
The cerebral cortex is a relatively new evolutionary addition to our nervous systems. Amphibians and their predecessors have no cortex at all, yet they have no trouble initiating, and perhaps even planning, sequences of behavior. Our brains are essentially amphibian brains on top of which has been added a cerebral cortex. Although I agree with the evolutionary framework proposed by Hughlings-Jackson, the book's discussion of behavior on [K&W:358] is very oversimplified.
In my presentation of a "bottom up" analysis of behavior, I will start with the spinal cord. The book's discussion of the spinal cord is broken into three segments; with the overview on [K&W:59-62], sensation on [K&W:383-387] and behavior on [K&W:367-368]. When all three segments are taken together, they give a fairly clear picture, but they leave something out, the spinal locomotor generator. The spinal locomotor generator is responsible for coordinating the "axial" muscles of our trunk. Two online references for the spinal locomotor generator are:
The full text of an article on the spinal locomotor generator of the leech, the lampry and the crayfish. The generator continues to operate even after it is disconnected from the brain.
Abstract of an article which states the widely held view that the ancient spinal locomotor generator (the article uses the term "network" rather than "generator") is still functional in quadrapedal walking.