x] Frontal and Prefrontal Areas 241 



I think Bianchi's point is well founded, and I think further that the same evidence will 

 strengthen a contention of mine, to be considered hereafter, that the " pivfrontal " cortex 

 is of low functional importance compared with the "frontal." 



In the next place Hitzig 1 and Munk make equally emphatic statements to the effect 

 that the dogs from which they removed the frontal lobes never showed any signs of 

 intellectual impairment. 



It is unfortunate that the above-mentioned observations on the effects of experimentally 

 produced lesions of the frontal lobe should be so full of discrepancies, as the only conclusion 

 possible after reading the controversy is in accordance with my opening statement, that we 

 cannot hope for definite information regarding the higher functions of the frontal lobes from 

 operations on low animals. 



CLINICAL DATA. 



Passing on to the teachings of clinical experience, we will first consider the suggestion, 

 that in the human brain the motor act is represented in front of the " intermediate 

 precentral " area. 



As to the occurrence of trunk paralysis analogous to that described by Munk in the 

 dog and monkey, the collected evidence may be said to be definitely negative, indeed this 

 applies to all gross forms of paralysis, for although in not a few instances of frontal 

 lesion some degree of hemiplegia or monoplegia has been noticed, authorities tell us that 

 in none has it been possible to exclude involvement of the precentral region or of the 

 motor tracts. 



In reference to special movements of the eyes and head, similar to those obtained by 

 Ferrier and others in the lower ape. and by Griinbaum and Sherrington - in anthropoids, 

 the evidence is different and the case extremely interesting. In a large number of recorded 

 instances, as Ferrier has pointed out, conjugate deviation of the eyes and a movement of the 

 head, both towards the side of the lesion, have been observed, while not so commonly weakness 

 of the superior rectus, abducens paralysis, and diplopia have been complications, and taking 

 an average of the cases in which localisation has been possible, the part of cortex destruction 

 of which seems specially liable to bring about these phenomena is that lying towards the 

 hinder end of the middle frontal gyms. In an endeavour to bring this into correlation 

 with what we know of cortical histology, two suggestive coincidences occur to us : first, 

 although the active area indicated by Griinbaum and Sherrington covers a large portion 

 of the outer surface of the frontal lobe, its centre lies at about the middle of the sulcus 

 rectus (I would say that the corresponding spot in the human brain is towards the hinder 

 end of the sulcus frontalis medius), and this comes partly within the area in the anthropoid 

 ape to which I have assigned " frontal " characters : secondly, the part found vulnerable in 

 the human being (the posterior part of the middle frontal gyms) is also enclosed within 



1 Hitzig, in believing that the frontal lobes are the seat of the highest intellectual faculties, really supports 

 Bianchi's view, but his conclusions are based on the lesson of comparative anatomy, that the development of the 

 frontal lobe keeps pace with that of the intellect. His experiments did not confirm his plausible argument. 



- The experience of these writers is as follows : " Our observations indicate that the frontal region, yielding 

 conjugate deviation of the eyeballs, presents such marked differences of reaction from the 'motor' area in the 

 Kolandic region that we hesitate to include it with the so-called ' motor' cortex ; it seems necessary to distinguish 

 it iu a physiological category separate from that. Spatially it is wholly separated from the Bulandic 'motor' area 

 by a field of ' iuexcitable ' cortex." 



c. 31 



