“Neural circuits linking activity in anatomically segregated populations of neurons in subcortical structures and the neocortex throughout the human brain regulate complex behaviors such as walking, talking, language comprehension, and other cognitive functions associated with frontal lobes.” 1
We also found this interesting quote from Science Daily on this topic of complex sensory motor behaviors and on the varying information on central pattern generators.
ScienceDaily (June 3, 2012) — “A new finding that motor cortex is a dynamic pattern generator upends existing theory with broad implications for neuroscience.”
“Maybe it is actually easier to understand than we thought. A new paper presents some compelling evidence that the motor cortex, rather than being command central, is more like a part of the machine, sending rhythmic signals down the spinal cord to orchestrate movement.”
"The electrical signal that drives a given movement is therefore an amalgam — a summation — of the rhythms of all the motor neurons firing at a given moment.” This is of course monitored (and modified) by one of our best friends, the cerebellum. 2
The cortex is where movement begins and where it ends; from areas 4, 4s and 6 in the precentral gyrus of the brain’s frontal lobe, down the spinal cord and out to the muscle through the peripheral nerve. It is also where the information from the body’s receptors feed back, to give updates on where the body parts are in space (proprioception) and how they are doing functionally (comparing information about length, tension, etc). It is about sensory and motor function. Motor function is based on sensory input. Good motor function is based on good sensory information. It is a subtle, beautiful, intricate symphony. And when one part goes wrong, the whole system can be thrown off.
Here is an example we sometimes use in our lectures and with our patients to make this point clear. Imagine an orchestra playing Beethoven’s beautiful Ode to Joy, a choral symphony for orchestra. Now imagine one of the musicians begins to play off key. In time, the musicians sitting around that musician who are most locally influenced by that off tune musician, soon become irritated and have troubles playing “in tune”. In time, if not rectified, the whole orchestra could be corrupted and being to take that lead as well. Hard to believe, but it makes the point that all it takes is one piece not playing well to change the outcome. Similar analogy, all it takes is one weak muscle or one painful joint and the outcome is skewed away from the optimal outcome and in time local dysfunction and compensation becomes an all encompassing compensation. The body’s function and operation, when proper, is an orchestra and orchestration with each piece doing a local job with a more global contribution to the bigger job. When all pieces come together appropriately it creates a symphony of flawless, effortless movement as seen in the video above.
Shawn and Ivo, the gait guys