Neural Mechanisms oj Decision Making 255 



AVERAGE RESPONSE OF LATERAL GENICULATE DURING 

 GENERALIZATION TO lOcps AFTER TRAINING TO 4cps 



100 SWEEPS 



lOcps on 

 Fig. 7. Average response computed from lateral geniculate during generalization 

 to ten per second flicker, after avoidance training using a four per second flicker 

 tracer conditioned stimulus. (From Weiss, Marc: Unpublished data.) 



flicker, each period beginning at a deleted flash and lasting for 

 625 milliseconds. Note the regularity of the computed waveform. 

 Similar regularities were observed in average responses computed 

 during generalization to ten per second flicker from dorsal hippo- 

 campus, centre median, nucleus reticularis, and medial supra- 

 sylvian cortex. * 



Figure 8A shows the average response waveform computed from 

 the visual cortex at this stage of training during correct performance 

 to a four per second flicker. 



Figure 8B shows a comparable average response waveform com- 

 puted from potentials recorded from the visual cortex during 

 generalized performance to a ten per second flicker. Note the 

 complex, irregular waveform. 



Figure 8C shows the average response waveform computed from 

 the visual cortex during correct performance to the ten per second 

 flicker after diff'erentiation. In contrast to Figure SB, note the 

 markedly increased simplicity and regularity of the waveform. 



I was impressed by the fact that these data might provide the 

 basis to test the hypothesis that the waveforms observed during 

 the generalization represented the interaction between an endogen- 

 ously generated representation, or memory, of the stimulus fre- 



*Histological verification of electrode placements has not yet been obtained. 



