436 DOMINICK P. PURPURA 



completely devoid of late activity. This suggests that the change in the s.c.r. 

 observed after GABA was not similar to that produced by progressive weaken- 

 ing of the applied stimulus, for if such were the case, it might be expected 

 that when the initial population of responding elements decreased by 40%, 

 the reduced response would have a time course similar to that of the initial 

 response. The fact that the response after GABA has an abbreviated time 

 course suggests that late components in the s.c.r. are more effectively blocked 

 by GABA than the early. Such a situation could arise if the elements contri- 

 buting to the late components of the s.c.r. were oriented closer to the pial 

 surface than those responsible for the early. Further discussion along these 

 lines is deferred until the effects of long chain oj-amino acids on developing 

 cortex can be considered. Although these differences are clearly shown in 

 Fig. 7 in records from a 5 day-old-kitten (Fig. 7 (5), (6)) and a 5 week-old- 

 kitten (Fig. 7 (7), (8)), they are best summarized with respect to changes that 

 are observed in early and late components of the s.c.r. and the spontaneous 

 electrocortical activity. 



The effects of Ce and oj-amino caprylic acid (Cg) on the s.c.r., the subse- 

 quent slow positive-negative sequence, and the background spontaneous 

 electrocortical activity are shown (Fig. 9) in records taken from a 5 hr-old- 





D 



I 



Fig. 9. 5-hr-old kitten. Effect of topical e-amino caproic acid (Ce) and co-amino 

 caprylic acid (Cg) on s.c.r. 's and succeeding long duration responses. S.c.r.'s 

 recorded 1 • 5 mm from site of stimulation. Left column, fast sweep (cal. 100 c/s); 

 right column, slow sweep (cal. 10 c/s). a. Control s.c.r.'s, note later positive- 

 negative sequences in slow sweep records, b. 1 min after Ce. c. Recovery of s.c.r. 

 10 min after flushing cortex with Ringer's solution, d. 20 min after c, control 

 prior to Cg application, e. 2 min after Cg. f. Recovery 20 min after removal 



ofCg. 



kitten. Both Ce and Cg depressed all components of the s.c.r. and increased 

 background activity (Fig. 9b, e). No differences were observed in the de- 

 pressant effects of these long-chain <o-amino acids on the s.c.r., but Cg 

 appeared to exert a more pronounced action on late potential sequences in 

 neonatal animals (<5 days old). Differences were more apparent in some- 

 what older animals. In 5-7 days old kittens, Ce depressed both near and 



