10 



John B. Calhoun 



terminations during both the initial 150 minutes of hyperactivity and the 

 following three, 6 p.m. to 6 a.m., 12-hour periods of normal heightened 

 nocturnal activity. The frequency, y, of terminating trips as a function of 

 distance, x, from home is described by the equation : 



y = exp (o 4- bx) (9) 



where h is the slope. The slope for trip-terminations during the hyper- 

 active period, 6i, is —0.2099; while 62, the slope for trip-terminations during 

 the 36 hours of normal nocturnal activity, is —0.1924. The t test 



61 — 62 



= -0.682 



VVar. (61 - 62) 



has a p value of 0.051 which indicates that slopes 61 and 62 do not differ 

 significantly. 



Therefore, it is concluded that the neural mechanism producing termina- 

 tion of trips is unaltered by the nearly sixfold increase in the incidence of 

 initiating trips accompanying initial exposure to a strange environment. 

 For this reason, the mean slope of —0.20115, i.e., (61 + 62) /2, was fitted to 

 both these sets of data shown in Fig. 3 as trips per rat per hour for compara- 

 tive purposes to emphasize the hyperactivity of initial exposure to a strange 

 environment. 



2.0 



1.0 



.02 



"eMOTlONAL " 

 I si. 2.5 hours 

 of Hyperaclivily 



10 



TERMINATION OF TRIP IN FEET 



Fig. 3. Frequency of terminating trips at successive distances from the home com- 

 partment in the unstructured Ferguson Alley. See Table la. 



