Adjunctive behavior induced by different conditions of wheel running

Physiology and Behavior, Vol. 14, pp. 507-510. Brain Research Publications Inc., 1975. Printed in the U.S.A.

BRIEF COMMUNICATION Adjunctive Behavior Induced by Different Conditions of Wheel Running 1 M. J. W A Y N E R 2 , G. S I N G E R a , K. CIMINO, J. STEIN AND L. DWOSKIN

Brain Research Laboratory, Syracuse University, 601 University Ave, Syracuse N Y 13210

(Received 17 December 1974) WAYNER, M. J., G. SINGER, K. CIMINO, J. STEIN AND L. DWOSKIN. Adjunctive behavior induced by different conditions of wheel running. PHYSIOL. BEHAV. 14(4) 507-510, 1975. - Adjunctive behaviors such as licking, nose poking, rearing, grooming and locomotion induced by intermittent wheel running were observed in 12 female hooded rats. Animals were studied both under scheduled and free wheel conditions. Although all of the observed behaviors were emitted at high frequencies during scheduled wheel turning activity, only revolutions and rearingsqocomotion increased significantly when compared to the free wheel condition when animals scheduled themselves. These data demonstrate again that adjunctive behavior can be produced in animals which are not deprived of food or water and support an explanation in terms of a nonspecific increase in motor excitability induced by the intermittance of schedule associated stimulation. Adjunctive behavior

Wheelrunning

Motor activity

Motor excitability

SINCE adjunctive behavior seems to arise from a nonspecific increase in m o to r excitability [3], the results of a recent study [2] which demonstrate that scheduled wheel running activity can induce licking, rearing and other types of behavior in animals under conditions of ad lib food and water are particularly important. In this experiment the behavior emitted during the scheduled test periods was compared to that observed in control animals placed in locked wheels for the entire test session. The purpose of the present experiment was to observe adjunctive behavior in rats during periods of scheduled wheel turning and under free wheel conditions. Results were similar to those of the previous study and indicate that some types of adjunctive behaviors are emitted frequently when wheel turning activity is scheduled and that these effects do not depend upon food or water deprivation. METHOD

Animals Twelve female hooded rats, 1 8 4 - 2 3 4 g in weight, were selected from our colony. Animals lived in individual living

Schedule induced behavior

cages and food and water were available continuously. Body weight was recorded daily.

Apparatus Animals were tested in an automatically programmable standard 14in. dia. Wahmann Co. LC-34 activity wheel [1]. A 5 cm dia. window covered with a wire grid, 14 mm squares, was placed over the entrance to the wheel. Water was available during the test session from a ball point stainless steel drinking spout which protruded 1 cm through the grid window 3 cm above the running surface of the wheel. A contact lickometer was attached to both the drinking spout and the wire grid. Contacts with the drinking spout and the wire grid, licks-pokes, as well as revolutions of the wheel were recorded by counters. A brake mounted colinearly with the shaft of the wheel permitted the wheel to be free or locked for various lengths of time. The duration of the free and locked periods was controlled by two independent timers. The wheel was enclosed in a box constructed of acoustical ceiling tile. A transparent Plexiglas window in one side of the box allowed direct observation o f the animal. Shaded fluorescent lights

zThis research was supported by NSF Grant GB-41297 and NIMH Grant 15473 and Training Grant MH-06969. We would like to express our appreciation to Prof. George Collier for the use of a programmable activity wheel. This research was carried out while G. Singer was an NSF Visiting Senior Foreign Research Fellow. Reprint requests to M. J. Wayner, Brain Research Laboratory, 601 University Avenue, Syracuse, NY 13210 U.S.A. 507

W A Y N E R ET/11..

508 i l l u m i n a t e d t h e inside o f t h e b o x c o n t i n u o u s l y d u r i n g t h e test session. Licks and r e v o l u t i o n s were r e c o r d e d b y c o u n t e r s a n d c u m u l a t i v e recorders.

s c h e d u l e d wheel for 10 days a n d t h e n 10 days in a free w h e e l a n d t h e reverse o r d e r for the o t h e r group. A w a t e r t u b e was available d u r i n g this part of the e x p e r i m e n t . C o n s e q u e n t l y , licks-pokes and v o l u m e o f w a t e r ingested in ml were also r e c o r d e d . T h e s c h e d u l e d w h e e l c o n d i t i o n was a fixed t i m e s c h e d u l e consisting of a 10 sec free wheel p e r i o d f o l l o w e d by a 45 sec l o c k e d wheel period. T h e r e were 15 such periods or i n t e r r u p t i o n s . The wheel was free for 2 min and 30 sec a n d locked for 11 rain and 15 sec for a total t e s t session time of 13 rain and 45 sec. All o b s e r v a t i o n s were r e c o r d e d d u r i n g t h e e n t i r e test session. In t h e free wheel c o n d i t i o n t h e a n i m a l was placed in the wheel for 14 min per day. R e v o l u t i o n s were r e c o r d e d for each self s c h e d u l e d i n t e r r u p t i o n , s t o p p i n g a n d t h e n starting to run again, for a t o t a l o f 15 i n t e r r u p t i o n s as well as for t h e first 2.5 m i n o f t h e test session. A f t e r the 15 i n t e r r u p t i o n s the a n i m a l c o n t i n u e d in the free wheel for t h e r e m a i n d e r o f t h e test session. Data were r e c o r d e d d u r i n g the 15 i n t e r r u p t i o n s a n d d u r i n g t h e t i m e r e m a i n i n g in t h e test session.

Procedure Each a n i m a l was placed in a free w h e e l for 14 m i n p e r day a n d t h e n r e t u r n e d to its h o m e cage for 14 days. T h e w a t e r t u b e was n o t p r e s e n t a n d o n l y r e v o l u t i o n s were recorded. During t h e n e x t 8 days an e x p e r i m e n t e r was present and rearings-locomotion, grooming, and revolutions were r e c o r d e d . These data c o n s t i t u t e d a baseline. Rearings were defined as s t a n d i n g o n t h e h i n d legs. L o c o m o t i o n was d e f i n e d as b o d i l y m o v e m e n t o f at least h a l f way u p t h e side o f t h e wheel. Data o n rearings a n d l o c o m o t i o n were c o m b i n e d a n d will be r e f e r r e d t o as r e a r i n g s - l o c o m o t i o n . G r o o m i n g was defined as self d i r e c t e d licking, b i t i n g a n d scratching. Animals were divided i n t o t w o groups, o n e g r o u p o n a 140 -

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DAYS FIG. 1. Mean revolutions for each group plotted as a function of days for each condition; baseline, free wheel, and scheduled wheel. Open circles for the group subjected to the scheduled condition first then free. Solid circles for the group subjected to the free condition first then scheduled. Broken lines connect the data obtained under the free wheel condition when animals scheduled themselves for 15 interruptions which required a mean time of 4 min. Solid lines connect the data obtained for 2 min and 30 see under free wheel conditions and for 15 interruptions (2 min 30 sec) under scheduled conditions.

ADJUNCTIVE BEHAVIOR AND WHEEL RUNNING

509

RESULTS

There are no significant differences between groups or conditions when compared in this way which indicates that when animals schedule themselves they tend to make the same number of revolutions but over a longer period of time. The activity seems to be emitted at a lower rate. Results on rearings-locomotion are illustrated in Fig. 2 w h e r e the mean number of rearings-locomotion are presented during baseline and the free wheel and scheduled wheel conditions as a function of days. The increase due to the schedule is obvious. The most dramatic change in the animals' behavior under schedule conditions was the obvious abrupt movements recorded as rearings-locomotion. Some preliminary data reveals that if naive animals are placed in a free wheel and permitted to remain until they maintain a relatively constant wheel turning rate, which.requires from 10 to 20 min, and then the wheel is locked, then rearingsqocomotion are emitted at a high rate. These responses diminish in frequency rapidly in about 6 to 9 rain; and, if animals are placed into the locked wheel directly on the next day, the behavior seems to recover spontaneously and then decays with a similar time course.

The data on wheel revolutions, rearings-locomotion, grooming, licks-pokes, and water intakes for the two groups were analyzed by individual analysis of variance for repeated measures; where one factor was the free wheel condition versus the scheduled wheel condition and the second was the order of treatment, free then scheduled or scheduled then free, and the third factor was days. There was no significant order effect. Significant differences occurred between scheduled and free wheel conditions only for wheel revolutions during the first 2.5 rain of available r u n n i n g t i m e , F ( 1 , 1 0 ) = 37.72, p<0.Ol, and for rearings-locomotion for the total test session, F(1,10) = 120.27, p< 0.01. Significant increases occurred in grooming, F(9,90) = 2.09, p<0.05, licks-pokes, F(9,90) = 2.83, p<0.01, and water intakes, F(9,90) = 3.85, p<0.01, over the 10 day test periods. There were no significant interactions between any of the conditions. These results demonstrate that when the opportunity to run in the activity wheel is scheduled or programed that the number o f revolutions and rearings-locomotion increased but grooming, licks-pokes, and water imbibed were not affected by the schedule. Grooming, licks-pokes, and water intakes did increase over each l0 day period. The effect on wheel revolutions is illustrated in Fig. 1 where the mean number of revolutions for both groups and baseline plotted as a function of days during each test period. The data from the group subjected to the scheduled condition first then the free is illustrated by open circles and the other group subjected to the free wheel condition first and then scheduled by the solid points. These data points are connected by solid lines. The differences between the free and scheduled conditions are significant. When the animals are in the free wheel condition they schedule their own activity and the number of revolutions made by both groups during 15 voluntary interruptions, which required approximately 4 min, are also presented in Fig. 1 and the data points are connected by broken lines.

DISCUSSION These data support the results of a previous study of behavior induced by scheduled wheel turning activity and demonstrate again that considerable adjunctive behavior is emitted when other activities are scheduled which does not depend upon prior food or water deprivation. In this experiment for a 10 sec free wheel period followed by a 45 sec locked period schedule significant increases occurred in wheel revolutions and rearings-locomotion but not in licks-pokes, grooming or water intakes. Since an increase in licks-pokes was reported in a previous study, some explanation for the discrepancy is necessary. In the present experiment, licks-pokes increased in the same manner as did revolutions but the increases were not statistically significant. These data were more variable.

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FIG. 2. Mean rearings-locomotion for total test session for each group plotted as a function of days for each condition; baseline, free wheel, and scheduled wheel. Open circles for the group subjected to the scheduled condition first then free. Solid circles for the group subjected to the free condition first then scheduled.

WAYNER t:'T AL.

510 The results of the present study demonstrate that significantly more adjunctive behaviors, in this case wheel turning and rearings-locomotion, are emitted during scheduled interruptions than when animals interrupt themselves in the free wheel condition. Although grooming, ticks-pokes, and water intakes all increased during the scheduled interrupted test sessions, the increases were not significant. When

a n i m a l s s c h e d u l e themselves under the free wheel condition, more adjunctive behavior is emitted than when animals were placed in a locked wheel [2]. Some preliminary data indicate that these adjunctive behaviors, such as rearings-locomotion, which are emitted soon after the wheel is locked persist for several minutes and then decrease rapidly in frequency.

REFERENCES 1. 2.

Collier, G. and E. Hirsch. Reinforcing properties of spontaneous activity in the rat. J. cornp, physiol Psychol. 77: 155-160, 1971. Singer, G., M. J. Wayner, J. Stein, K. Cimino and K. King. Adjunctive behavior induced by wheel running. Physiol. Behav. 12: 493-495, 1974.

3.

Wayner, M. J. Specificity of behavioral regulation. Physiol. Behav. 12: 851-869, 1974.