An Interpretation of the Functions of the Frontal Lobe

Ideas concerning the functions of the frontal lobes have undergone a radical change during the past few years. The older hypotheses (which are too well known to require discussion here) were based upon certain conditions such as injuries, tumors, or inflammatory lesions of various types, in which the general effects of disease upon the brain as a whole could by no means be excluded. Moreover, in certain types of disease, the symptoms were more or less the same no matter what the localization. Strauss and Keschner,14 18 for example, found a higher incidence of personality changes and mental phenomena in cases of tumors of the temporal lobes than in those affecting the frontal lobes. In recent years neurosurgeons have demonstrated conclusively that either frontal association area may be removed almost in its entirety without producing more than slight defects in the functional capacity of the individual.12 The classical account by Brickner2 of a man in whom both frontal lobes had been extensively resected, followed by similar cases studied by Ackerly,' by Karnosh,18 and by Hebb8 presented a very striking picture, bringing to a focus the syndrome of frontal lobe deficiency. Brickner attributed to the frontal lobes the function of synthesis of intellectual operations. To quote from his condusions (page 319): "Only one function is considered as primarily affected. This is the elaborate -association or synthesis into complex structures of the simpler engrammatic products associated in the more posterior parts of the brain. There is a diminution in the amount of synthesis, which places a limit upon the degree of attainable complexity of thought. Through this deficiency, the large variety of secondary and tertiary defects becomes manifest, and the overt personality