438 



DOMINICK P. PURPURA 



12 Days 



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Fig. 1 1. Comparative effects of Ce and Cg on near and distant s.c.r.'s in 10- and 

 12-day-old litter-mates. (1), (2), (9) and (10) control; s.c.r.'s recorded 1-5 mm 

 (upper channel) and 4 mm (lower channel) from the site of stimulation; (3), (4), 

 (11) and (12) 2 min after topical Ce; (5), (6), (13) and (14) recovery after rinsing 

 cortex with warm Ringer's solution; (7), (8), (15) and (16) 2 min after topical 

 Cg; note depression of early and augmentation of late components in near 

 response in (7) and (15), as well as depression of far response in (7) and minor 

 alteration in far response in (15). Further explanation in text. Fast sweep, 100 



c/s; slow, lOc/s. 



components of near responses and depression of distant s.c.r.'s (Fig. 12, 

 (11), (12)). Paroxysmal discharges, apparently triggered by the surface stim- 

 ulus and initiated close to the site of stimulation, were propagated to distant 

 sites at a velocity similar to that of distant s.c.r.'s. By the fourth postnatal 

 week, both Ce and Cg rapidly augmented all components of near s.c.r.'s as 

 in mature animals (Fig. 8 (8)). 



In view of the finding that at a developmental stage when near s.c.r.'s were 

 augmented by Ce and Cg. i.e. 3-4 weeks, no effects were observed on s.c.r.'s 

 recorded 4-5 mm from the site of stimulation, a series of experiments were 

 performed on adult cats to determine whether the differential action of long- 

 chain w-amino acids on near and distant s.c.r.'s represented a final matura- 

 tional change. The results of these experiments are summarized in Figs. 13 

 and 14. Following topical application of Ce to both near and distant recording 

 sites, s.c.r.'s evoked 1-5 mm from the site of stimulation (suprasylvian gyrus) 

 were rapidly augmented, but no significant change was observed in distant 

 responses (Fig. 13b). When late components of the near s.c.r. exhibited a 

 further increase in amplitude, distant late components were also augmented 

 (Fig. 13c), but the early remained essentially unchanged. The origin of the 



