J. p. SEGUNDO, C. GALEANO, J. A. SOMMER-SMITH AND J. A. ROIG 275 



of amplitude and duration (or even complete suppression) of cortical 

 response waves (Figs. 2, 5, 6, 8). Susceptibility was different for each 

 peak. Pi was resistant to the acquired influence of T (Fig. 6 — left column 

 — second Hue). Ni was insensitive in certain preparations (Figs. 8; 9 — 



BEH EFFECT OF TONE 



% COND RESP 



Fig. 7 

 LEARNING CURVE. On abscissae, number of training sessions; on ordinatcs, per- 

 centage of tones giving behavioural responses. Curve with narrow line and 

 open circles, percentage of all responses; curve with broad line and black circles, 

 percentageof 'typical', stereotyped response (see text). Top graph: cat exhibit- 

 ing frequent but variable reactions to T (head raising or turning to right or 

 left, blinking, etc.). Bottom graph: cat exhibiting a frequent 'typical' stereo- 

 typed response. BEH., behavioural: RESP., response. 



left column; lo; 11) but responsive in others (Figs. 6 — Ictt column — 

 third line; 9 — II). The P2- N2- P3 complex was modified by T initiation: 

 effects upon P3 were notorious (Figs. 6 — left column; 8; 9; 10 — I; 11 ; 

 12); N2 frequently responded well (Figs. 6 — left column — fourth line; 

 8 — IV; 10 — I), but, occasionally, was not affected by or even became 



T 



