J. p. SEGUNDO, C. GALEANC), J. A. SOMMER-SMITH AND ]. A. ROIG 27I 



P2 was practically continuous with P3 (Figs. 6, 1 1 ) ; as N2 developed, separa- 

 tion between P2 and P3 became evident (Figs. 6, 8, 10, i r, 12); when N2 

 was large, P3 preserved its individuality but P2 became a minor indenta- 

 tion between Ni and N2 (Figs. 6, 8, 10). All delayed negative oscillations 

 were included as N3 (since latencies and shapes were variable, this group 



EEG EFFECT OF T ALONE 



Tl 



Tn " 



'\' 'ii,',iu.fj 



T-CESSSS 180 

 a. 



'^iA^({i^\k4^4^j^^ii^lj^^ 



S£C 00 tit*'i»¥t'ff^f^^•/^^^i^'\fM^^^H^h^ 



2 ^ VW^Vf,^1'*^>^'V**.^^1W%^^ 



Fig. 4 

 EEG EFFECTS OF TONE APPLIED ALONE (without background SS). Ti (first application of T) : 

 'desynchronization'. Tn (after numerous applications) : T was no longer ctfcctive (habituation). 

 T-CESS SS 180 (after 180 associations with cessation of SS) : {a) if applied against a background 

 'relaxed' rhythm, T produced 'desynchronization' ; (/)) even when applied against an 'activated' 

 background, T was followed (time 24 seconds) by reinforcement of slow rhythms and spindles 

 lasting for about 20 seconds (up to time 34 seconds). CESS., cessation. 



