1895.J Impressions, fyc., to Voluntary Movements. 91 



doctrine (now generally admitted to be erroneous) that " feelings 

 of movement " were, in the main, "concomitants of the out-going 

 current." 



Further, I have endeavoured to show that sensory impressions and 

 the activity of sensory centres are the real guides for volitional 

 action, that they, in fact, do just such work as has been attributed to 

 supposed cortical motor centres, and that it is a fundamental error to 

 imagine that cortical motor centres exist for the performance of 

 voluntary movements, altogether apart from the other motor centres 

 that are concerned with the production of reflex or secondary 

 automatic acts.* 



I have contended, in short, that true motor centres exist only in the 

 pons bulb and spinal cord, which may be called into activity in 

 different ways, according as the stimulus comes, in the one case (a) 

 from the cortex, for volitional movements ; or as it comes (6) through 

 afferent nerves and lower sensory centres, as in reflex acts. 



In regard to movements of the latter category (6), there is no 

 room for difference of opinion, and the results of the experiments 

 of Drs. Mott and Sherrington are thoroughly in harmony with what 

 is generally admitted. Section of all the sensory roots proceeding 

 from a limb must abolish, as it has been found to do, all reflex move- 

 ments in this limb. 



We may turn therefore at once to the consideration of (a) move- 

 ments initiated from the cerebral cortex (so-called voluntary 

 movements), and strive to ascertain in what various modes such 

 movements may be rendered impossible, or, in other words, how 

 paralysis of such movements may be occasioned. 



It may be noted here that the writer was the first, in 1869, in 

 opposition to then prevalent physiological notions, to postulate the 

 existence of various sensory centres in the cerebral cortex,f and that 

 some years before any experimental evidence was brought forward on 

 the subject. About the same time he showed how this hypothesis 

 sufficed to throw light upon the nature of various forms of speech 

 defects,^ and in this he was followed by Broadbent, still before any 

 attempt had been made to localise such centres. || 



* " On the Neural Processes underlying Attention and Volition," ' Brain,' April, 

 1892. 



t " On the Localisation of Function in the Cerebral Hemispheres," ' Journ. of 

 Ment. Science,' January, 1869; and " On the Muscular Sense and the Physiology 

 of Thinking," ' Brit. Med. Journ.,' May, 1869 . 



J " Physiology of Thinking," ' Fortnightly Review,' January, 18G9 ; and " Defects 

 of Speech in Brain Disease," 'Brit, and For. Mod Chir. Review,' January and 

 April, 1869. 



" On the Cerebral Mechanism of Speech and Thought," ' Med. Chir. Trans.,' 

 1872, p. 180. 



(I See Ferrier in ' Phil>Tmns.,' Part II, 1875. 



