196 



Information Storage and Neural Contiol 



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05 I 10 20 30 



Time in minutes after "conditioning" 

 train of 3 /sec flicker 



Fig. 6. Time course for "decay" of conditioned rhytJimic response of single 



cortical unit. 



low frequency intermittent light (Fig. 5C). After a few minutes 

 of stimulation the three per second flash was discontinued and 

 thirty seconds later a single flash resulted in a series of bursts 

 having a three per second frequency (Fig. 5D). Single flashes 

 delivered at intervals longer than thirty seconds were less and 

 less likely to provoke such a rhythmic response but occasional 

 rhythmic responses to single flash were noted as long as twenty 

 minutes after the end of the conditioning train (Fig. 6). This 

 seems a particularly clear illustration of the capacity of the polar- 

 ized cells to retain some representation of an imposed stimulus 

 pattern for a relatively long period of time. Indeed the order of 

 magnitude of this time interval is itself significant. It correlates 

 well with the data of Gerard (14), Duncan (13) and others (44, 

 53, 54) on the abolition of learned responses consequent to massive 

 electro-shock delivered at various intervals following the training 

 session. 



