DRIVING FUNCTIONS

The nervous system seems to work by disinhibition (Deutche). To keep very sensitive electro-chemical elements from going off at random due to noise or even thermal effects and still maintain sensitivity the whole system must be under constant inhibition. Function then requires disinhibition, How does this work?. Does the nervous system inhibit the inhibitors? But for a response the causal information must be in some sense specific, the recognition network at least must effect its own disinhibition. Or is the disinhibition more global? Perhaps a visual stimulus disinhibits the entire visual cortex, the specific recognition network activated depending on the precise nature of the stimulus. But what about motor output? Several possibilities: 1. the entire motor system is disinhibited, 2.the specific response network is disinhibited by its own activity, 3. the recognition network disinhibits the specific response network due to a previous learning process.

" The cortical motor system of primates is formed by a mosaic of anatomically and functionally distinct areas. These areas are not only involved in motor functions, but also play a role in functions formerly attributed to higher order associative cortical areas. In the present review, we discuss three types of higher functions carried out by the motor cortical areas: sensory-motor transformations, action understanding, and decision processing regarding action execution. We submit that generating internal representations of actions is central to cortical motor function. External contingencies and motivational factors determine then whether these action representations are transformed into actual actions.. "Rizzolatti G, Luppino G., The cortical motor system. Neuron. 2001 Sep 27;31(6):889-901.

What is an “ internal representation” of an action? Consider a simple verbal response to a question: “What color is it?” – “Red” We can say the response, sign the response, write the response with either hand, scratch it in the dirt with a stick, trace it in the sand with our feet. The motor responses are highly variable potentially. What do they all have in common?

Many of these responses are similar from a motor behavior point of view –writing or scratching or tracing- yet not identical from a mechanical point of view. There are at least two different response modalities- vocal, mechanical. Is there, can there be a common neurological element after the visual recognition process, that is common to all of them? Something which is producing the response, or driving the response network, a driving operation or “driving function”?