1885.] on the Motor Centres of the Brain, dr. 259 



Hence the higher functions of the braiu exercised when that 

 organ is energising the reasoning of the mind, are absolutely de- 

 pendent ujion the reception of energy from the sense perceptive areas. 



But my only point with reference to this part of the brain is to 

 attempt to determine how far they are connected with the motor 

 centres in the performance of a voluntary act. With the mechanism 

 of choice and deliberate action I have nothing to do, but there can be 

 no doubt that the part of the brain concerned in that process of the 

 mind is directly connected with the motor region, as indicated on 

 this diagram, to which I would now return. From what I have here 

 written you read, arranged schematically, the psychical processes 

 which for the sake of argument vv^e may assume are carried on by the 

 mind in these portions of the cortex. 



I wish to point out that we have structurally and pliysiologically 

 demonstrated with great probability the paths and centres of these 

 psychical actions. There is no break ; the mere sight of an object 

 causes a stieam of energy to travel through our sense areas, expanding 

 as it goes by following the widening sensory paths were represented, 

 and at the same time we feel our intellect learns that new ideas are 

 rising up and finally expand into the process of deliberate thought, 

 concerning which, all we know is from that treacherous support, 

 namely introspection. 



Then comes impulses to action, and these follow a converse path 

 to the receptive one just described ; the nerve energy is concentrated 

 more and more until it culminates in the discharge of the motor 

 corpuscles. We might represent the whole process of the voluntary 

 act by two fans side by side, and the illimitable space above their 

 arcs would serve very well to signify the darkness in which we sit 

 concerning the process of intellectual thought. 



What I have hastily sketched is the outline of the process of an 

 attentive or voluntary act. I say attentive advisedly, for I wish now 

 to put forward the view that the proper criterion of the voluntary 

 nature of an act is not the mere effort that is required to perform it, 

 but is the degree to ivMch the attention is involved. The popular view 

 of the volitional character of an act being decided by the effort to 

 keep the action sustained is surely incomplete, for in the first place 

 we are not seeking to explain our consciousness of an effort, we 

 endeavour to discover the causation of the effort. Our sense of effort 

 only comes when the will has acted, and that same sense is no doubt 

 largely due to the information which the struggling muscle sends to 

 the brain, and possibly is a conscious appreciation of how much energy 

 this motor corpuscle is giving out. 



Now to give you an example. I see this tambour and decide to 

 squeeze it, and do so. Now this was a distinctly voluntary act ; but 

 the volitionary part of it was not the effort made, it was the deliberate 

 decision to cause the movement. 



I may now point out that in this whole process we say, and say 

 rightly, that our attention is involved so long as we are deliberating 



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