THE liRAlN 01 MODERN MAN 



789 



coinolut loiis in relation with the Liptiiiiu'd t'licl ot the superior and middle 

 temporal sulci has already been cU'seribed and is important m that it gives 

 these areas of the cortex a greater coiuolutional rKhness than is true ol any 

 ol the great anthropoids. 



SIGNIFICANCE OF CONXOLUTIONAL COMPLEXITY IN THE HIMAN BRAIN 



If a single statement might cover the characteristic leatures ol the 

 lateral aspect ot the human hemisphere in contrast to all other primates, it is 

 that the com|)le\ity ol the coiuolutions and the tortuousness ol the lissures 

 render impossible a unilorm description m man, \\ hile the relatixe simplicit>' 

 of these leatures in all simian brains discloses the discrete territorial bound- 

 aries almost at lirst glance. 



Although the human brain has made great advance in its relative weight 

 when compared with the anthro[)oid brain, both absolutely and in relation 

 to body weight, its chief superiority lies in its intricate compk-xity ofconvolu- 

 tional arrangement. As applied to the frontal area this obser\ation becomes 

 l^articularly lorcelul. The frontal lobe, olten spoken of as the silent area, is, as 

 a matter of fact, now credited with such functions as those cinmected with the 

 regulation of the higher laculties of the mind, the de\ flopnuMit of pt-rsonahtN , 

 the formation ot all those associational memories which enter into and lorm 

 personal experience and thus bespeak the degree of intellectual de\elopment. 

 A similar coiu'olutional expansion of tlu' occipital lobe is an indication ol the 

 extent to w hich \isual lunction has extended its associational significance and 

 the added degree in which it contributes to the general s\ nthesis of sensory 

 combinations entering into the ex|)erience of the indi\idual. That the tem- 

 poral and ])arietal lobes ha\e been somewhat outrun b\ the ex])anding 

 complexity of the frontal and occipital lobes is perhaps not surjjrising, inas- 

 much as these two intermediate areas of tlu' brain ha\c' alwa\s presented a 

 certain predominance because ol tlu' ixpresentation within tlu'ir cortical 



