Neural Mechanisms of Decision Making 271 



It is of interest that in this animal, once the central stimulus had 

 been established as informationally adequate by conditioning, the 

 peripherally established c/ifferrntiated response appeared to generalize 

 to the central stimuli. Differential response to central ten per 

 second and four per second stimuli was perfect on the twelfth 

 session, which was the first occasion on which the four per second 

 stimulus was presented following conditioning to central ten per 

 second stimulus. The animal seemed to benefit from the previous 

 differential experience with peripheral stimuli at these frequencies. 

 Whether or not such generalization will take place reliably, it is 

 obvious that these two animals have been trained to diff"erentiate 

 between two sequences of events of identical energy occuring 

 at the same central site. Thus, the temporal pattern of events at a 

 place in the brain can serve as information. Further, since the con- 

 stituent pulses of all central stimuli are but two milliseconds 

 wide, the temporal pattern of significance here is the slow modula- 

 tion frequency characterizing the stimulus trains. Such evidence 

 does not demonstrate that the patterns of slow labeled potentials 

 which appear in certain brain structures are information, but 

 it does establish that slow patterns at a place can be information. 



Clearly, it is desirable to explore the propagation of such centrally 

 delivered difTerential stimuli to other brain regions from the input 

 site before and after they are established as adequate conditioned 

 stimuli. The interaction of such pulsed central stimuli with con- 

 current photic stimuli must be investigated, and the behavioral 

 as well as electrophysiological consequences of concordant and 

 discordant central and peripheral tracer stimuli are presently being 

 studied in our laboratories. Such studies should provide additional 

 insight into the functional role of labeled potentials in performance. 



Some additional information of interest has been obtained from 

 Cat 10. Table II shows the consequences of a number of trials in 

 which one or the other of the visual cortex electrodes was stimu- 

 lated together with some other cortex placement. Note that 

 differentiated conditioned response was obtained fairly consistently 

 when the stimulated electrode pair included the right visual cortex 

 electrode but not when it included the left visual cortex electrode. 

 It is pertinent to recall that the central pulses were biphasic. These 

 data suggest that whatever the nature of the neural mechanism 



