16 



John B. Calhoun 



For 71 of the 73 rats previously discussed with reference to the distaiu^o 

 of trip-terminations, a count was made of the total feet traveled each half- 

 hour during the first 2| hours of exposure to the alley. A similar analysis 

 was prepared for the 26 rats, considered further in Section III, A, 5, which 

 emerged into the alley more than momentarily and for which the recording 

 system functioned properly. 



For each set of data, results are quite similar (Fig. 6). Activity con- 

 tinuously declines during initial exposure to a strange environment. But 

 the important point is that this decline begins from an extremely elevated 

 state of hyperactivity. From Table la it may be calculated that the average 



z i 100 



K I 



I- U. — 



llJ tt 



^ X 



*- < 



Q 2 



10 



12 3 4 5 



CONSECUTIVE 30 MINUTES IN ALLEY 



Fig. 6. Hyperactivity in a strange environment: Curve A represents the mean 

 activity level of 71 rats immediately after first exposure to the Ferguson Alley. Curve B 

 similarly gives the mean response of 26 rats to the NIH Emotional Activity Alley. 



round trip approximates 10.44 feet. During the normal nocturnal period of 

 activity, trips occur at the rate of 1.58 per hour. This means that in this 

 one-dimensional alley rats travel 8 feet per half-hour on the average when 

 adjusted to their environment. As may be seen from Fig. 3 the activity is 

 in(;reased nearly twenty times normal during the initial half-hour in this 

 strange environment. Projection of the curves, shown in Fig. 6, indicates 

 that a normal level of activity will be reached by 3—4 hours of adjustment. 

 Such decay curves of hyperactivity suggest that the rats secrete some 

 humoral agent upon their initial exposure to strange stimuli such as repre- 

 sented by the activity alley. This humoral substance increases the rate of 

 firing of the neuronal net comprising the governor which determines onset 

 of diffuse motor activity, such as trips out into the alley. As this substance 

 is degraded, the frequency with which this governor emits signals initiating 

 trips decreases until normal behavior is achieved. 



