Factors in the Neural Bases of Intellect and Emotion *

Through some recent observations of patients with various cerebral disturbances it has been possible to learn something of the anatomy of the pathways of intellect, and of the way they function. The basic observation was the immense difference between the sequelae of biand uni-lateral frontal lobectomies. After bilateral extirpation, the changes in thinking are panoramic; they are so all-inclusive that they appear in almost every act, and the whole composite personality seems altered." 2, On the contrary, unilateral lobectomy results in changes which are so few that they are hard to discern. This fact has been established for man by Penfield and Evans,2' Fox and German,'4 Vincent and Dereux,23 Jefferson,"6 Stookey and Scarff,22 and for monkeys and chimpanzees by Fulton and Jacobsen,'2 Jacobsen,'5 and Messimy and Finan.'9 After hemispherectomy (nondominant) the changes are equally few, as attested by Dandy,9 Gardner,'3 O'Brien,20 and McKenzie.'8 So striking and important a phenomenon calls for explanation. It appears possible to give such an explanation. The frontal part of the cortex has been conceived of as a place where there occur additional combinations of intellectual engrammes which, in themselves, are built up further caudally. This deduction has been made by a number of observers. Particularly, it was derived from a study of Mr. "A," who had survived bilateral frontal lobectomy. The principle loss "A" suffered appeared to be the capacity to form the most complex aggregations of thoughts, only the more simple ones being left. The situation was summarized in the idea that "complex synthesis" of thought had been lost, the loss being of