ANALYSIS OF SOME EVOKED SYNAPTIC ACTIVITIES 439 



8 Days 21 Days 



7 , 8 



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AA/V\A 



Fig. 12. Comparative effects of Cr on s.c.r.'s in 8- and 21-day-old litter-mates. 

 Sweeps and calibrations as in Fig. 11 . (I) and (2) control s.c.r.'s recorded 1 -0 mm 

 from site of stimulation; (3) and (4) 2 min after topical Ce; (5) and (6) after 

 complete recovery from depressant effects of Ce, and 2 min after Cs; differences 

 in the action of Ce and Cg are apparent; note in particular changes in late com- 

 ponents of s.c.r. after Cs; (7) and (8) control near (upper channel) and 4 mm- 

 distant (lower channel), s.c.r.'s; (9) and (10) immediate effects of Ce; rapid 

 augmentation of early and late components of near s.c.r. with more pronounced 

 action on late components; distant response unaffected; (11) and (12) onset of 

 Ce-induced convulsant activity. 



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Fig. 13. a. Near (1 -5 mm) and distant (6 mm) s.c.r.'s evoked in suprasylvian 



gyrus of adult cat with stimuli threshold for late negative component, b. 20 sec 



after application of Ce to both recording sites, c. 40 sec after b. d. Recovery 



after rinsing cortex with Ringer's solution. Cal. 100 c/s; 0-1 mV. 



late component appearing in the distant s.c.r. after Ce was established by 

 employing a series of recording electrodes spaced 1 mm apart and adjusting 

 stimulus strength to threshold for the early, but sub-threshold for late 



