LASHLEY— CEREBRAL FUNCTION 275 



ably, the areas receive excitations from other parts of the cerebrum 65 

 and it is probable that all parts of the kinetic system ,irt are capable of 

 mutual influence. Postural facilitation and inhibition may themselves 

 be habitual responses, but the present experiments indicate that they 

 are rather generalized and not independently organized for each specific 

 manipulative habit. 



Recent work in general tends to emphasize the complexity of neural 

 functions. We must hesitate to ascribe an exclusive or precise function 

 to any neural structure, for the evidence points rather to the view that 

 observable behavior is always the product of the interaction of many 

 neural systems and that the function of any system is dependent on its 

 temporary physiologic relation to other systems. This is particularly 

 true of the finer adaptive responses of the intact animal which are 

 subject to inhibition and facilitation by innumerable factors. Their 

 execution depends on preparatory postural adjustments, emotional and 

 other dynamic facilitation, as well as integration of impulses from many 

 exteroceptors. 67 The total mass of excitation is effective both through 

 the specific efferent patterns activated ar.d also through the general 

 dynamic effects which alone a?e incapable of producing the overt motor 

 reactions elicited. The experiments reported here indicate that the 

 dc'vtrostimulable areas are rather more concerned with the maintenance 

 of excitability and the regulation of postural reflexes than with the 

 excitation and control of finely integrated adaptive movements. 



65. I have made several attempts to isolate the area from other parts of the 

 cortex by circumsection but have not yet been successful. The literature on this 

 point is conflicting. Marique (Brain 8:536-538, 1885) reported the same results 

 from circumsection as from excision of the area. Exner and Panetli (Arch. f. 

 d. ges. Physiol. 44:544-555. 1889) found similar results but were inclined to 

 ascrihe them to interference with the blood supply of the area. Schafer (Jour. 

 Physiol. 26:23-25. 1901) reported one case of complete circumsection without 

 paralysis. He does not report histologic examination of the lesion, however, 

 and in view of the difficulty of the operation there is not sufficient evidence 

 that the isolation was complete. 



66. In this discussion, I have disregarded the important conception of static 

 and kinetic functions advanced by Hunt (Arch. Neurol. & Psychiat. 4:353. 1920) 

 because the evidence does not show clearly to which of his systems the elect n>- 

 stimulable cortex is to be referred. The postural influences of the area would 

 indicate a static function. What I have called the dynamic or "priming" func- 

 tion is rather a kinetic function, but is more primitive than the activities implied 

 in Hunt's conception of the neokinetic system. 



67. The statement that every act of the intact organism involves the par- 

 ticipation of every neuron within the central nervous system is probably no 

 more of an exaggeration than are the extreme theories of precise localization of 

 function or of isolated conditioned reflex paths. 



