m] Post-amputation ('/uni(/t's in the Cerebral Cortex 59 



Taking now the tacts hearing mi localisation gleaned from these cases, and setting them 

 in order, we find: (I) that in three eases of amputation of the leg, two of them below the 

 knee, the cell changes were must intense in the group situated on the mesial .surface of 

 the hemisphere, and that they also affected, although to a minor extent, the large marginal 

 group on the convexity; it therefore follows that this part may be marked down as the 

 centre for movements of the foot and ankle. (2) In one of these leg cases the amputation 

 \\as made above the knee, and since, in addition to the above-mentioned groups, degeneration 

 was also found in the next group lower down on the convexity, that is the relatively small 

 cluster lying more or less on the free surface of the ascending frontal convolution, above 

 the level of the superior frontal sulcus, we may conclude that the cells of this group, as 

 well as some proportion of cells in the overlying large marginal cluster, dominate muscles 

 acting on the knee joint. (3) Reasoning by deduction we may assume that the centre for 

 the representation of thigh movements lies in the next cluster of cells, situated immediately 

 above the annectant buttress or gyrus. (4) Since the scattered cells existent in the annectant 

 buttress have not shown any signs of degeneration, either in the cases of amputation of the 

 leg or arm, and since we have reason for supposing that shoulder movements are presided 

 o\er b\- the group of cells lying immediately below this level, we are left to conclude that 

 the cortex of this buttress is the trunk centre. This view gains in credence from the fact 

 that, in the anthropoid ape, trunk movements have been constantly elicited by excitation 

 of cortex at the level of the upper germ ; indeed, to the physiologist, this flexure is a very 

 important dividing landmark between arm and leg centres, and, as I have previously mentioned, 

 in both man and ape the bend in the Rolandic fissure is nothing more than the surface 

 expression of the underlying buttress. (5) My reason for believing that the cluster of cells 

 situated immediately below the annectant gyrus may deal with shoulder movements is that 

 in one case of amputation of the arm close up to the shoulder joint, which was associated 

 with extreme atrophy of the shoulder muscles, this cluster showed pronounced degeneration; 

 whereas, in another case in which the amputation was near to the elbow joint, and the 

 shoulder muscles had preserved much of their normal size and tone, the same cluster was 

 intact 1 . (6) A study of degeneration present in these brains favours the belief that movements 

 of the arm (elbow, finger, and wrist) have a relatively extensive representation in the cortex. 

 For in the two cases of amputation through the upper arm, just alluded to, diseased cells 

 were found along the stretch of cortex reaching from the shoulder cluster I have indicated to 

 within 10 or 15 mm. of the lower extremity of the fissure of Rolando, but not quite to the 

 lower extremity of the Betz cell area. (7) In one case of amputation at the wrist joint 

 degeneration was found only at the lower extremity of the above-mentioned arm field, so 

 in a normal human brain I would locate wrist and finger movements slightly above an 

 imaginary line continued backwards from the inferior or second frontal sulcus. (8) The few 

 giant cells lying below this level, which have remained intact in all these instances and 

 which constitute the lower extremity of the Betz cell area, must govern neck movements. 

 (!') Applying Professors Sherrington and Griinbaum's anthropoid ape scheme to the human 

 brain, it is found that there is close agreement on all the above-mentioned points, but 

 when we try to fit on the area, excitation of which produced movements of facial muscles 

 those of the jaw, eyelids, nose and ears we find that there are no true giant cells which 

 we can look upon as presiding elements resident in the homologous area. We do, however, 



1 In connection with this it may be remembered that in my second case of Amyotrophic Lateral Sclerosis the 

 upper arm muscles had escaped wasting and the cluster of cells here indicated was preserved. 



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