Page:Mind (Old Series) Volume 12.djvu/446

 EECENT DISCUSSION ON THE MUSCULAR SENSE. 433 between a sensory and a motor centre. If this be so, the time has come for abolishing altogether the distinction of sensory and motor cortical centres ; they are all sensori-motor. (d) Implication of Will. "The conflict of mental moods or motives," says Dr. Bastian, "is sometimes slight and sometimes complex (entailing what we now term inhibitory processes), before what is called a resolution or Will to do a certain action is arrived at. As Hobbes quaintly says: 'The whole sum of desires, aversions, hopes and fears, continued till the thing be either done or thought impossible, is what we call Deliberation '. Here then we have intellect in action, with absolutely nothing of motor activity concerned with its manifestation" (Brain, p. 135). Further on he describes fibres as issuing from certain regions of the cortex, and by means of these "our Intellect plays upon subjacent motor centres when we desire to perform this or that so-called c voluntary action ' ". This " playing '' ends in move- ment. Dr. Bastian gives this doctrine as a complete displacer of the " out-going current " theory of Dr. Bain. But " intellect in action " means physiologically the action of cortical centres : these excite motor processes ; and what initiates a motor process is to all intents and purposes motor an "out-going current". One may call it sensory or kinsesthetic ; that is mostly a matter of terms. (3) Cortical Localisation. There is no agreement either on the localisation of movements in general or of muscular sensations in particular. The interpretation of "motor centres" is far from complete ; in fact we must use the words " motor " and " sen- sory " centres as provisional. (4) Psychological Import of Muscular Sense. The tendency of recent discussion is to put more stress on afferent impressions than on efferent processes. The impressions from skin, fasciae, ligaments, joints, and from the sensitive nerves in muscle, ar^ thrown together as the physical side of feelings of movement. I have, above, repeated some possible objections to this position ; but even if it were demonstrated, a difficulty remains. As a psychological fact, feelings of movement that is, feelings of energy expended are radically opposed to passive feelings or sensations. If, therefore, feelings of movement are, like sensations, the mental side of afferent processes, how is it that feelings of movement are opposed to all other feelings ? What peculiarity in their nervous substratum corresponds to this antithesis? This is not fully explained yet, and when it is explained the psychological fact remains precisely where it was. The question of the conditions of the " muscular sense '' is a purely physiological matter, and if feelings of movement are not concomitants of the " out-goirg current," then, as Prof. Bain has said (Senses and Intellect, 3rd edit., p. 77), "the most vital distinction within the sphere of mind is bereft of all physiological support ''. That is all. 28