252 Information Storage and Neural Control 



tion of the ten per second flicker, potentials at the same frequency 

 clearly appear in visual cortex and lateral geniculate, with less 

 marked evidence of response in the intralaminar nuclei and the 

 reticular formation. The cortical response suddenly shifts to a 

 hypersynchronous slow wave at a frequency between four and five 

 cycles per second, while the animal shows a startled movement 

 and four seconds later performs the conditioned lever press estab- 

 lished to a four per second flicker. Notice that the lateral geniculate 

 maintains ten per second potentials during this period, although 

 potentials at lower frequency are visible in the reticular formation 

 and occasionally in the intralaminar nuclei. 



A comparable observation has been reported by Majkowski (16). 

 After a rabbit was trained using a three per second light, generaliza- 

 tion was obtained upon presentation of a five per second light. As 

 can be seen in Figure 5, during such a generalization a three per 

 second wave can be observed in motor cortex, although the re- 

 sponse of visual cortex is at five per second. Related findings have 

 been described by other workers (6). 



Data of this sort suggest that during generalization a neural 

 system, which has become established as a consequence of experi- 

 ence with the intermittent conditioned stimulus (CS), is somehow 

 released by the new stimulus, but discharges with the character- 

 istic temporal pattern of the original conditioned stimulus. This 

 system seems to include the mesencephalic reticular formation and 

 the intralaminar nuclei in association with the visual cortex. It is 

 interesting that during generalization phenomena of the sort 

 described, regions of cortex other than the region of the conditioned 

 stimulus, such as ectosylvian or medial suprasylvian, tend to display 

 potentials at the frequency of the peripheral stimulus. 



Additional data on this phenomenon have recently been obtained 

 in our laboratory by Marc Weiss (26) who trained a cat to perform 

 a conditioned avoidance response to a four per second flickering 

 light. After establishment of this response, the cat generalized 

 readily to a ten per second flicker. Figure 6 (Top) shows the 

 EEC's obtained from various brain regions during such generaliza- 

 tion. Note the irregular slow activity in the visual cortex contrasted 

 with the regular ten per second response in the lateral geniculate. 

 Figure 6 (Bottom) shows records obtained after differentiation of 



