1895.] Suppressions, <-c., to Voluntary Movements. 93 



duce such paralysis just as certainly as lesions in the bulbar motor 

 centres themselves. If the lesion be situated in the auditory word 

 centre (AC) it will produce "word-blindness" as well as loss of 

 speech ; though if it be situated in the glosso-kinaesthetic centre 

 (GKC) it will produce loss of speech alone. In opposition, however, 

 to the doctrine as to the strict localisation of aphasia, as a symptom 

 resulting only from lesions in the third frontal convolution (Broca's 

 convolution), I have long maintained that precisely similar defects 

 would result from destruction of the commissural fibres (#) in any 

 part of their course thus affording an explanation of the many 

 cases recorded by Meynert and others in which aphasia had been 

 caused by a lesion in the " Island of Beil." 



Again, it has long been known that damage to the internuncial 

 fibres (y) in any part of their course would also cause loss of speech 

 (i.e., paralysis of speech movements), similar in kind to that caused by 

 lesions in the bulbar motor centres (BMC). 



In what has been said above we have illustrations of the importance 

 of afferent impressions and the revived activity of afferent centres for 

 the production of the voluntary movements occurring in articulate 

 speech. And if, instead of looking to the processes which occur when 

 our own thoughts reveal themselves in spontaneous speech, we turn to 

 what happens when we read the recorded thoughts of another, it will 

 be found that a further relation with sensory centres has to be 

 established before such reading aloud can occur. 



The impressions from the printed page impinge upon the visual 

 centre (fig. 2, VC), and are thence transmitted across commissural fibres 

 to related portion of the auditory centre, whence the stimuli pass, as in 

 spontaneous speech, to the glosso-kinaesthetic centre and thence on to 

 the bulb. The consequence is, that where lesions occur in the course 

 of these visuo-auditory fibres (z), the individual is unable to read 

 aloud, and he is unable to name objects or even single letters, 

 although he will immediately repeat words or letters as soon as he 

 hears them. He cannot carry out the voluntary movements con- 

 cerned with speech at the instigation of the visual sense, though he 

 can do so at the instigation of auditory impressions. We get thus 

 at the roots of Will and find them definitely localised in sensory 

 centres.* 



II. Limb Movements. The visual sense in the case of limb move- 

 ments performs the same office as the auditory sense in the case of 

 speech. New movements of limbs are learned largely by aid of the 

 visual sense, supplemented by associated kinsesthetic impressions. 

 So that subsequently, when we desire to repeat familiar movements, 



* Cases illustrating the effects of lesions to the count: issures between the auditory 

 and the visual word centres may be found recorded in ' The Brain as an Organ of 

 Miml,' 4th edition, pp. 640 647. 



