NA TURE 



93 



THURSDAY, NOVEMBER 30, 1876 



FERRIER ON THE BRAIN 

 The Functions of the Brain. By David Ferrier, M-.D., 

 F.R.S. With numerous Illustrations. (London: Smith, 

 Elder, and Co., 1876.) 



II. 



SINCE it is certain that the movement of a limb may 

 be occasioned by an idea, an emotion, or a sen- 

 sation, and also by the reflex of an external stimulation ; 

 since, moreover, it is certain that such a movement may 

 be arrested by an idea or emotion ; and since there is 

 good ground for the hypothesis that the cerebral hemi- 

 spheres are, if not the sole agents, at any rate indis- 

 pensable accessories in the production of ideas and 

 emotions, we have every right to conclude that the 

 hemispheres play a part in the normal production of 

 many movements ; and that ideas and cerebral processes 

 are the subjective and objective aspects of one and the 

 same effect. But experiment proves that many, if not 

 all, these movements can be executed in the absence of 

 the hemispheres, therefore the hemispheres are not indis- 

 pensable but accessory factors. This leads to the question. 

 What part do they play ? And this again to the questions, 

 Are all cerebral processes or only some of them, ideas 

 emotions, and sensations, the others being simply mole- 

 cular movements which propagate their excitation to cen- 

 tres of muscular innervation ? 



I understand the Hitzig-Ferrier view to be this : One 

 set of cerebral processes, having their centres or terminal 

 stations in a limited region of the cortex, are sensational, 

 emotional, and ideal; another set, having also all their 

 centres or terminal stations in a limited region of the 

 cortex, are motor. I am not quite sure that this repre- 

 sentation is exact, for in both writers there is absence of 

 explicit definition. But this much at least may be taken 

 as exact, that they profess to have discovered limited areas 

 of sensory and motor stimulation, and within these areas 

 limited spots for particular sensations and particular 

 movements. The interpretation must, of course, rest on 

 a basis of fact, yet the facts observed may be accepted 

 without forcing acceptance of the interpretation. There 

 is general agreement on the facts with great want of 

 agreement as to the conclusions. I have already suggested 

 that the discoveries of Hitzig and Ferrier are of great im- 

 : tance ; but only as finger-posts for anatomists seeking 

 pathways of stimulation, not as inductive stations for 

 1 active inferences. All we can say at present is that 

 ctrical stimulation of certain spots is followed by cer- 

 jiain movements ; but how the stimulation reaches the 

 pnotor nerves is as dark as before. 



I Thus far, therefore, the part played by the cerebral pro- 



" ss is only recognisable as an incitation ; it certainly 



s not effect the movements, it only incites the motor 



ijans. And thus far it is on a level yf\t\i peripheral 



fucitations, such as the incitation of laughter by tickling 



he sole of the foot ; or of vomiting by tickling the fauces. 



Laughter is a function of a complex apparatus, and this 



ipparatus may be stimulated in very different ways from 



ery different starting-points —an idea, a sight, or a touch. 



/omiting, again, follows from a blow on the head, acidity 



n the stomach, a disgusting sight, a smell, or a tickling 



Vol. XV.— No. 370 



of the throat. No one considers the sole of the foot and 

 the fauces to be centres or terminal stations for the func- 

 tions of laughter and vomiting. Why, then, when we see 

 movements of the limbs, the eyes, or the tail following 

 stimulation of the cerebral cortex, are we to conclude these 

 movements to have their centres in the cortex ? The foot 

 may be removed or the sole rendered insensible, yet 

 still laughter will be stimulated by ideas, sights, &c., as 

 before. In like manner the spot of the cerebral cortex 

 may be removed or destroyed, yet still the limbs will move 

 a5 before. Nay, not only the cortical spots, but the whole 

 hemisphere may be removed, and still the limbs will move 

 as before. 



For anatomical purposes we make a wide distinction 

 between grey matter and white, and a still wider distinc- 

 tion between central and peripheral nerve- substance. 

 Physiologically such distinctions are, I conceive, erro- 

 neous, the whole nervous system being one. But the 

 distinction between a centre — i.e., a place \to which 

 stimulations are carried, and frofn which motor impulses 

 issue — and a peripheral region where stimulations begin 

 or end — is both a physiological and an anatomical 

 division usefully maintained. According to this defini- 

 tion of a centre, we may doubt whether the cortex of 

 the cerebrum has any claim to be called a centre, or 

 group of centres, whether, in fact, it is not a peripheral 

 region, the processes of stimulation in it being of the same 

 order as the processeses of stimulation in the skin, or 

 mucous membranes, i.e., simply those of peripheral in- 

 citation. 



This is the paradox to which allusion was made at the 

 close of my former article. As it would occupy too much 

 space for development here, and as I have worked it out 

 in a volume now at press, I merely suggest it for specu- 

 lative readers, and pass on to Dr. Ferrier's book. 



First as to his facts. It has been urged against his 

 localisations that he has employed a too powerful current. 

 On this subject I have no right to an opinion, but incline 

 to accept his reply as satisfactory ; though one must not 

 overlook the fact remarked by Carville and Durct, that 

 very different movements may be occasioned by the 

 stimulation of one and the same spot according to inten- 

 sity of the current — a fact analogous to what is observ^ed 

 in stimulations of the skin. It has been urged by Hitzig, 

 and also by Braun (Eckhard's '' Beitrage," vii., 133, 137), 

 that in Dr. Ferrier's experiments the same movements 

 follow stimulation of different spots, even when these 

 spots are situated in the different regions recognised as 

 excitable and non-excitable. The objection is not only 

 triumphantly answered by Dr. Ferrier, but is answered 

 by the introduction of an idea which is of great signifi- 

 cance : — " The mere fact," he says, " that movements 

 result from stimulation of a given part of the hemisphere 

 does not necessarily imply that the same is a motor 

 centre in the proper sense of the term. It will afterwards 

 be shown that the movements which result from stimula- 

 tion of the regions in question are expressive of sensation, 

 and that the character of the movements furnishes an im- 

 portant index to the nature of the sensation " (p. 147 ; 

 compare also p. 163). 



As an answer to his critics this seems conclusive. But 

 does it not throw a serious difficulty in the way of his 

 hypothesis ? If, as he luminously suggests elsewhere. 



