x] Frontal nd Frcfrontal Areas 239 



liglit on ;i number of observations made by previous writers on the functions of the frontal 

 lobe, and in the following discussion some profit may accrue from viewing these observations 

 in the new light. 



Experimental Dtita. 



Taking a short retrospect of the work of experimenters, we soon see from the con- 

 tradictory results arrived at, that only a limited amount of gain is to be obtained by study 

 in this direction. 



First concerning the influence of faradic stimulation, there is almost complete unanimity 

 among experimenters that the anterior part of the frontal lobe, the region which they have 

 distinguished by the name " prefrontal " and that which in all likelihood corresponds to my 

 " prefrontal " area, is electrically "silent"; indeed, by some who have had the widest experience 

 in this class of research, it is said that in the case of the ape, and this is particularly 

 interesting, because of all animals its frontal lobe resembles that of man most, it is 

 possible by judiciously applied stimulation to obtain a reaction from any part of the cerebral 

 cortex save this. On pausing for a moment to reflect on such a remarkable fact the 

 histological appearances offered by the field at once come to mind, it is remembered that 

 it is a part in which the fibre endowment reaches its lowest ebb, and in particular it is 

 one m which the fibres of even medium size are scanty and those of large calibre entirely 

 wanting ; further, it is a field where the largest cells are by comparison with those in other 

 regions puny and where the cell representation in general is seen at its worst ; and without 

 opening up physiological controversies on cortical excitation it is to my mind not so singular, 

 when we take these histological data into consideration, that it should exhibit negative 

 reactive qualities. 



With the hinder part of this region, that which might correspond in part to my 

 "frontal" area, it is different. For Ferrier firmly maintains that certain movements of .the 

 facial and ocular muscles, as well as dilation of the pupil, may be evoked by local stimulation ; 

 also in Sherrington and Griinbaum's figure published in their first paper, the frontal area 

 marked " eyes " and indicated by vertical lines seems to lie partly within my " frontal " area, 

 and the experiments of others, notably Beevor and Horsley, on the orang, point in a 

 similar direction. In looking for an explanation of these interesting points I would suggest 

 that the " frontal " strip of cortex may have some of the higher motor properties possessed 

 by the " intermediate precentral " area ; this, however, is a point to which I shall return again. 



Of experimenters who would ascribe motor functions of a more direct character to the 

 frontal lobe, there is one whose views cannot be passed over, I refer to Munk, who sees 

 in the frontal lobe, or in an inexactly defined part of it, the motor area for trunk muscles, 

 because its extirpation, both in the dog and in the monkey, in his hands produced a certain 

 amount of trunk paralysis (abnormal arching of the back, &c.) which was of long duration. 

 But positive as the terms are in which Munk expresses his convictions it is extraordinary 

 that no other experimenter of note has been able to confirm his results. 



So much for the effects of stimulation and for the supposed role which the " frontal " 

 lobe bears in regard to motion; we have now to turn to a series of experiments designed 

 for the purpose of throwing light on the much more important question of the activity 

 of the frontal lobe in relation to intellectual faculties. But here the narrative is made up 

 of a series of contradictions still more confusing in their effect. 



