90 Dr. H. C. Bastian. On the Relations of Sensory [May 2, 



or lower, immediately produces a lasting motor paralysis in the limb 

 thus apaesthete. 



The interpretation of these results seems at first sight very difficult. 

 The authors of the paper, after referring to views which I have put 

 forward in reference to the fundamental importance of sensory 

 impressions in the production of voluntary movements, give expression 

 to the following explanation : " We think these experiments go even 

 further than his arguments in pointing to the influence of sensation 

 upon voluntary movement, inasmuch as they indicate that not only 

 the cortex, but the whole sensory path from periphery to cortex cerebri, 

 is in action during voluntary movement." 



This interpretation of their interesting experimental results is one 

 which I cannot accept because it is opposed to other thoroughly 

 ascertained facts. Clinical investigation has established the fact that 

 in cases of complete hemianaesthesia due to lesions or functional 

 defects in the posterior part of the internal capsule, there is not only 

 no paralysis but little or no impairment in the ability to perform, 

 under visual guidance, even the most delicate movements with the 

 apaesthete limbs. This shows therefore that it is not necessary, as 

 they suggest, for " the whole sensory path from periphery to cortex 

 cerebri " to be in action during the performance of voluntary move- 

 ments. It was the knowledge of these facts, made known by clinical 

 investigation, that caused me to be much perplexed when Dr. Sherring- 

 ton kindly showed me some of the animals on which he had been 

 experimenting. The reality of the paralysis was obvious, but how 

 were we to account for the fact that the interruption of the sensory 

 channels from a limb in one part of their course produced this almost 

 complete paralysis, \vhilst the interruption of these channels higher 

 up (in the brain itself) gave rise to no such results ? I was for a 

 time quite unable to explain the apparent discrepancy, though 

 further consideration seemed to remove the difficulty. 



A brief exposition will, I hope, suffice to throw light upon this 

 question, as well as upon the extent to which afferent impressions and 

 the activity of their related centres are really needed for the produc- 

 tion of voluntary movements. 



I have for some years contended, in opposition to very generally 

 accepted views, that there is no evidence to prove the existence of 

 motor centres in the cerebral cortex ; whilst, on the other hand, 

 there is much evidence to show that the cortical regions supposed to 

 be motor, are, in reality, sensory centres of kinsesthetic type.* The 

 postulation of the existence of motor centres in the cerebral cortex 

 had its origin in, or, at least, derived its principal support from, the 



* "The Mxiscular Sense: its Nature and Cortical Localisation," 'Brain,' April, 

 1887. 



