270 



Information Storage and Neural Control 



resulting in failure to perform in response to the S^ were scored 

 as correct only when bracketed by correct performance of the 

 conditioned response to the S . Four per second bursts were 

 usually 25 milliseconds in duration, although response could be 

 elicited by shorter bursts. Ten per second bursts were usually 10 

 milliseconds in duration. Central pulse trains at different modula- 

 tion frequencies were equated for total electrical energy. "Carrier" 

 frequency was usually 200 cycles per second, but response could also 

 be elicited reliably at 100 cycles per second. Carrier pulse width 

 was 2 milliseconds. Threshold current for performance was found 

 to be between 1.8 and 2.1 milliamperes. Note that the occlusion 

 threshold at the stimulation site for concurrent peripheral and 

 central stimulation had been 4.0 milliamperes. 

 ^^Figuie 15 shows the learning curve for Cat 10. Stimulus par- 

 ameters were as for Cat 4, but the opposite significance was at- 

 tached to frequency. Threshold current was around 1.8 milli- 

 amperes. 



CAT 10 

 CENTRAL CONDITIONING USING BILATERAL STIMULATION 

 OF VISUAL CORTEX 



8 9 10 II 

 SESSIONS 



CUMULATIVE TRIALS 



I 1 1 1 1 1 : 1 1 1 1 — 



12 ' 59 ' 96 ' 117 I 167 ' 203 

 37 71 107 142 183 



26 



48 



64 



— I — 

 84 



15 



21 



~~i — 

 27 



90 



35 



Fig. 15. As Plgure 14, but in tliis animal the significance of the stimulus fre- 

 quencies was reversed. (10 per second — S , 4 per second — S^). Note apparent 

 transfer of previously established peripheral frequency discrimination to central 



stimuli. 



