Yesterday, I spoke about expressionism in terms of large sweeping movements of the body, such as those a dancer would make. Yesterday I also thought that it might be just a little oxymoronic to consider a small format painting as expressionistic. I admit that I may have been a little hasty in making that determination. I came to this conclusion by considering the pianist. The pianist is an icon of expressions, which can range from intimate soft tones; fine movements of the fingers playing a complicated rhythms, each hand working independently from the other; to vigorous motion of the arms and hands, depending upon the composers’ instructions.
I assume that everyone has had an experience in which he or she struggles to put an idea into words. Is it possible for a composer to conceive a work that is not playable by him or any other musician? Is it possible to relay an appropriate message from a painter’s mind to her musculature to replicate any form conceived her mind?
Vertebrate nervous system
According to Walle Nauta, renowned neuroanatomist, the basic central nervous system of all vertebrates can be thought of as a 3-neuron system. The primary sensory and motor neurons are interconnected through a ‘great intermediate net’.
“In higher primates, the total number of brain cells is commonly estimated to be of the order of 10 billion of which number no more than a few millions are motor neurons. These figures suggest that many mammalian brains contain at least as many as 2000 intermediate neurons to each motor neuron, a surprising ratio when it is realized that it is realized that it is only by way of motor neurons that the activity of the central nervous system can be expressed in movement, whether in the form of simple reflex or a complex, goal directed behavior.” 
Since the decision-making process for activating or inhibiting a motor neuron, depends on the interaction of 2000+ neurons (except in the case of the simple reflex) it is reasonable to believe that there is a neural basis for the inability to express some ideas. Putting ideas into words requires the use of the musculature, as does every other means of expression to the world outside one’s head.
 Nauta, W.J.H. & Karten, H.J. A general profile of the vertebrate brain with sidelights on the ancestry of cerebral cortex. In The Neurosciences: Second Study Program, eds. F. O. Schmitt and F. G. Worden, pp. 7-26. New York: Rockefeller University Press 1970