866 A MANUAL OF PHYSIOLOGY 



exclusion it has been supposed that, in addition to, or partly 

 in virtue of, their associative function, they are the seat of intel- 

 lectual and psychical operations. The intellectual function 

 has been more particularly assigned to the frontal lobes, and 

 with great probability, although we have little real knowledge 

 to guide us to a decision. Extensive destruction and loss of 

 substance of the pre-frontal region may sometimes occur with- 

 out any marked symptoms. But usually there is restriction 

 of mental power or it may be loss of moral restraint. Thus in 

 the famous ' American crowbar case/ an iron bar completely 

 transfixed the left frontal; lobe of a man engaged in blasting. 

 Although stunned for the moment, he was able in an hour to 

 climb a long flight of stairs, and to^ answer the inquiries of the 

 surgeon. Finally, he recovered, (and lived for nearly thirteen 

 years without either sensory or motor deficiency, except that 

 he suffered occasionally from epileptic convulsions. But his 

 intellect was impaired ; he became fitful and vacillating, profane 

 in his language and inefficient in his work, although previously 

 decent in conversation and a diligent and capable workman. 



Flechsig supposes that his great anterior association centre in 

 the frontal lobe is concerned in the retention of the memory of all 

 conscious bodily experiences, especially those connected with volun- 

 tary acts. The great posterior association centre he imagines to be 

 engaged in the formation and collection of ideas of external objects 

 and of the ' word pictures ' which represent them, and with the 

 preparation of speech in respect of the thoughts to be expressed and 

 the form of expression, the office of the Broca's area (but see p. 864) 

 being to execute the mechanical part of the process by transforming 

 these thoughts into actual spoken words. This posterior association 

 centre may be looked upon as the seat of intellect in the narrower 

 sense, as the anterior is of will and feeling. 



The experiments of Franz on the relation of the cerebral associa- 

 tion areas, and especially the frontal area, to certain acquired habits 

 are of interest. Cats were allowed to acquire certain habits involv- 

 ing simple mental processes, and then it was seen how these were 

 aflected by cortical lesions. After bilateral extirpation of the frontal 

 lobes (the area anterior to the crucial sulcus) newly-formed, but not 

 long-standing, habits are lost. This cannot be due to shock, since 

 other brain lesions are not followed by loss of the habits. Extirpa- 

 tion of one frontal area usually causes a partial loss of newly-acquired 

 habits, or, rather, a slowing of the association process leading to 

 unusual delay in the execution of the movements connected with 

 the habit. Habits once lost after removal of the f rentals may be 

 relearned. 



The influence of psychical events upon bodily functions is well 

 known, and has been more than once illustrated in preceding pages. 

 The converse question of the influence of bodily states upon psychical 

 events has also been raised, especially in connection with the genesis 

 of emotions. Some psychologists assume that the bodily changes 

 associated with such emotions as grief, fear, rage, or love, are not 

 evoke'd as a consequence of the emotions, but that the bodily changes 

 follow directly the perception of the exciting fact e.g., a spectacle 



