CHAPTER 6 



GENERAL COMMENTS 



The foregoing chapters have presented in detail various aspects 

 of the phosphate metaboHsm of brain tissue, both in vitro and 

 in vivo. The purpose of the present chapter is to comment briefly 

 upon some of the general points which have not previously been 

 discussed. 



Comparison of the Types of hiformation Obtained from Experiments 

 in vivo and in vitro 



The ultimate object of any study of the metabolism of an organ 

 is the detailed description of events taking place in the intact 

 organ when functioning normally in vivo. The manner in which 

 this description is given depends partly upon the orientation of the 

 information obtained and in the present context is largely bio- 

 chemical. At first sight it would appear most appropriate to carry 

 out such studies under conditions closely approaching the normal 

 functional state of the organ. Descriptions of ways in which this 

 problem has been approached with respect to the brain in vivo, 

 together with some of the results obtained formed the major part 

 of Chapters 1 and 2. Attempts to relate metabolic changes to 

 changes in functional activity have been made in two principal 

 ways; either with animals subjected to operative procedures or 

 with animals not so subjected. The first group comprises larger 

 animals such as the cat or dog under anaesthesia the skull of which 

 is opened, the brain exposed, and changes in functional activity 

 following a given treatment are detected by means of the electro- 

 encephalograph. The second group comprises smaller animals 

 such as the rat or mouse, which have been subjected to differing 

 stimuli and the change in cerebral functioning detected by clini- 

 cally recognizable signs. Though the animal in this condition 

 might be considered to be in a state more physiological than one 

 subjected to operation, nevertheless the latter has provided the 

 bulk of the information relating a metabolic event in brain to a 



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