THE ANTERIOR OR FRONTAL ASSOCIATION CENTER 589 



The Anterior or Frontal Association Center. The frontal area is 

 more closely connected with the motor areas and the centers for the somesthetic 

 sense. With injury to this area the individual shows weakness in attention, 

 in reflection, and in control over the expressions of anger, self-appreciation, 

 and other activities that are expressive of personal volitions and emotions. 



The American crowbar case is a classical instance of lesion of the frontal 

 lobe. A young man of twenty-five had an iron bar, an inch and a quarter 

 in diameter and over three feet long, driven through his skull and brain 

 by the premature explosion of a blast of powder. He not only recovered, 

 but lived for twelve years afterward. At the post-mortem examination the 

 puncture was found to be through the prefrontal lobe, anterior to the coronal 

 suture. 



This man was considered a most efficient workman and foreman before 

 the injury. After his recovery he was fitful, impatient of restraint, capricious, 

 obstinate; was most inconsiderate of his associates, profane, passionate; 

 from a shrewd business man he was changed to the intellectual level of a 

 child and was regarded by his associates as mentally unbalanced. 



A summary of fifty cases of pathological lesions of the prefrontal areas of 

 the human brain is given by Williamson. The mental traits of thirty-two are 

 summarized in the following terms: "A condition of mental decadence; a 

 dull mental state; loss of power of attention; loss of memory; loss of spon- 

 taneity; the patient takes no heed of his surroundings; sleeping during the 

 greater part of the da}', or remaining semi-comatose." Yet these patients are 

 able to walk about and execute well coordinated muscular activities of all 

 kinds that do not involve complex intellectual activity. 



The Parietal Association Centers. Special mention is made of this 

 association area because there is increasing evidence that it is the parietal 

 region of the brain, rather than the frontal, as popularly believed, that is 

 most intimately concerned with acts and powers of imagination, idealization, 

 and reasoning. It is the region through which the individual maintains his 

 interests and relations with the external world as against his own body. The 

 parietal association center is more closely related to the visual, auditory, and 

 speech centers of the cortex. The great musician Bach had an exception- 

 ally well developed parietal region. 



On the Cortical Centers in General. For purposes of clearness 

 in presentation, the cortical centers have been discussed one by one, but the 

 /eader is guarded against the thought that their activities are in any sense 

 isolated. A motor area does not usually act in the absence of sensory or af- 

 ferent stimulation in the actual living body, whether it may do so on occasion 

 or not. Neither do sensory impressions arising in the peripheral sense organ 

 make their way over definite tracts to the brain and cortex and arouse sensa- 

 tions alone. Sensations do not occur independent of motor activities on the 

 one hand, and of intellectual acts through the association centers on the other. 



