J. OLDS AND M. E. OLDS 



177 



Slcwdcv.-. All 



1062 Anlenor Rhinencepka 



\X 



V 



Fig. 18 

 Series of experiments on single-unit response recorded from anterior rhinencephalon. I. Before 

 stimulation. II. After stimulation without reinforcement. III. After reinforcement. IV. After 

 waiting for unit to slow down (about 5 minutes), reinforcement procedure is undertaken a 

 second time, and a photographic record is made during reinforcement; large Litticc-type 

 artifact indicates 60-cycle sine wave stimulus. V. Still later, after another wait, attempt is made 

 to correlate stimulation with pauses, but this is unsuccessful. Later an electronic device was 

 made to correlate stimulation with long silent periods, and the procedure caused some unit 

 responses to cease altogether. 



several minutes, with response amplitude decreasing in an orderly fashion. 

 Then the unit response would disappear for a period of some minutes, to 

 return at the original amplitude. At other times, the repetitive activity 

 would continue at a high level for longer periods. One might suspect that 

 a hippocampal seizure had been started by the reinforcement procedure, 

 except for the fact that movement of the electrode in these cases reveals no 

 similar activity in neighbouring cells. 



The second type of changes (Figs. i8 and 20 III) were not greatly 

 different from the first, but in these cases, the rapid responding caused by 

 reinforcement seemed much more like the original sporadic responding, 

 although its frequency was far greater. There was no tendency for the 

 rapid responding to be accompanied by decrement in amplitude. It 



