Perceptualand Motor Skillr, 1990, 70, 355-360.
O Percepmal and Motor Skills 1990
HOME-CAGE OPEN-FIELD AMBULATION AFTER MAZE LEARNING I N MICE ' BEATRICE KVIST AND RITVA-KAJSA SELANDER h o Akademi UniuersiQ Summary.-The present paper indicates that it is with appropriate methods, i.e., maze learning and a not-previously used home-cage open-field, possible to observe a learning-induced ambulation increase in a Familiar environment lacking novel cues. This finding is at variance with an earlier one achieved by electromagnetic recordmgs indicating a decrease in activity in the home-cage after passive avoidance conditioning.
The idea that learning a new performance activates the learner gave the impetus to the present work. The learning-induced level of general activation in animals lower than primates was thought to be reflected in measurable overt movements. There is now much evidence supporting this line of thought. Firstly, Lagerspetz, Raitis, T i r i , and Lagerspetz (1968) indicated that open-field ambulation in mice increased after active avoidance conditioning as compared to pseudoconditioned mice, w h c h displayed an activity decrease. Secondly, Mitani, Ando, and Nagata (1972) trained white rats in a food-reinforced runway and found that the trained rats displayed higher general activity in an activity wheel than did the untrained control group. Thirdly, Milcovic, Paunovic, and Joffe (1976) observed that open-field activity in rats was generally increased by prior avoidance conditioning. Lagerspetz, Kvist, and Lagerspetz (1980) demonstrated that an increased learning-induced open-field ambulation occurred independent of type of learning task and incentive used. There was, however, a problem with this phenomenon, which seemed to be influenced by the familiarity of the environment, namely, a learning-induced general activation as measured electromagnetically in the home-cage of the animal did not occur after passive avoidance conditioning. The activity level even decreased in comparison with that before learning. This outcome was thought to be due to the fact that the Animex Activity Meter is equipped with an arousing ticking noise, accompanying the animal's every step or movement. The noise might even have triggered the animal to an excessively high prelearning activity level, which could only decrease. Also the conditioning took place in a shuttlebox equipped with certain acoustic signals, indicating inhibition of activity, which might have been transferred to the postlearning situation in the home-cage. Consequently, the objective of the present work was to investigate the possibility of recording a home-cage open-field ambulation increase after learning using improved 'Direct correspondence to B. Kvist, Ph.D., Department of Psychology, h o Akademi University, Nunnegatan 4, SF-20500 Finland.
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B. KVIST & R-K. SELANDER
methods. Ambulation before and after a noiseless maze-learning procedure was recorded in a completely noiseless and nondisturbing home-cage open field to observe an increase in learning-induced ambulation in a familiar environment.
Subjects Ten 9-rno.-old male Swiss albino mice were each housed in a separate open field (see Apparatus). Food and water were available ad libitum until the beginning of the learning procedure, during which access to food was restricted. The testing started at the same hour every afternoon in a room temperature of approximately 23OC. The animals were housed and tested in a windowless room, which was artificially lit. They were kept on a 12 hr light112 hr dark cycle. Apparatus Ten home-cage open fields, each of which consisted of a circular wooden arena (diameter 40 cm) painted white, with a 20-cm high white wall, were used. The arena was covered with 250 g of shavings. The top of the field was covered with a wire net to which a water bottle was attached. During the activity recordings a circular, colorless plastic film (diameter 40 cm) was placed upon the wire net. The plastic film was divided by thin black lines into 19 partitions. A linear 11-point maze (157 x 22 x 18 cm) made of a galvanized iron plate with detachable partitions, was used for the maze learning. Procedure Home-cage openyield ambulation recordings.-Each animal lived undisturbed in its own home-cage open field during a period of five days. The following two days the open-field ambulation of the mice was recorded. To cause minimal disturbance to the mouse during the recording, the water bottle was removed and a plastic film was laid upon the wire net on the top of the field. The film was divided by thin black lines into 19 partitions to aid marlung the track of the animal on a similarly divided map of the film. The recordings were performed in a manner suggested by Broadhurst (1960), that is, by marking how many times an animal moved from one partition to another. Each move indicated an ambulation score and the sum of scores within a 2-min. period indicated the individual ambulation scores of an animal. To obtain a control group, the ambulation scores recorded on two successive days were averaged and the mice divided into two matched groups of five animals each. After the matching procedure the old shavings were replaced by new ones. During the maze-learning period, open-field arnbulation
HOME-CAGE OPEN-FIELD AMBULATION BY MICE
357
recordings were performed twice daily: about five min. before and about 22 min. after the learning period. Maze learning.-The experimental animals ran the maze on six successive days. Error scores and running times were recorded. The animals were given access to standard laboratory pellets for 2 min, in the goal box and for 20 rnin. in 3-1 glass jars, after which they were put into their home-cage open fields and activity was recorded again. The control group was put into an empty plastic trough (38 x 22 x 15 cm) after their ambulation was recorded to spend exactly the same amount of time there as their matched pairs spent in the maze. After this, the control animals were put into glass jars and were given access to standard laboratory pellets for 22 rnin. ad libitum. All animals received approximately 3 g laboratory pellets in their home-cage open field during the night.
RESULTSAND DISCUSSION The maze was almost completely learned in the six days of experimentation. The group mean of the running time diminished significantly (t, = 6.08, p
O Percepmal and Motor Skills 1990
HOME-CAGE OPEN-FIELD AMBULATION AFTER MAZE LEARNING I N MICE ' BEATRICE KVIST AND RITVA-KAJSA SELANDER h o Akademi UniuersiQ Summary.-The present paper indicates that it is with appropriate methods, i.e., maze learning and a not-previously used home-cage open-field, possible to observe a learning-induced ambulation increase in a Familiar environment lacking novel cues. This finding is at variance with an earlier one achieved by electromagnetic recordmgs indicating a decrease in activity in the home-cage after passive avoidance conditioning.
The idea that learning a new performance activates the learner gave the impetus to the present work. The learning-induced level of general activation in animals lower than primates was thought to be reflected in measurable overt movements. There is now much evidence supporting this line of thought. Firstly, Lagerspetz, Raitis, T i r i , and Lagerspetz (1968) indicated that open-field ambulation in mice increased after active avoidance conditioning as compared to pseudoconditioned mice, w h c h displayed an activity decrease. Secondly, Mitani, Ando, and Nagata (1972) trained white rats in a food-reinforced runway and found that the trained rats displayed higher general activity in an activity wheel than did the untrained control group. Thirdly, Milcovic, Paunovic, and Joffe (1976) observed that open-field activity in rats was generally increased by prior avoidance conditioning. Lagerspetz, Kvist, and Lagerspetz (1980) demonstrated that an increased learning-induced open-field ambulation occurred independent of type of learning task and incentive used. There was, however, a problem with this phenomenon, which seemed to be influenced by the familiarity of the environment, namely, a learning-induced general activation as measured electromagnetically in the home-cage of the animal did not occur after passive avoidance conditioning. The activity level even decreased in comparison with that before learning. This outcome was thought to be due to the fact that the Animex Activity Meter is equipped with an arousing ticking noise, accompanying the animal's every step or movement. The noise might even have triggered the animal to an excessively high prelearning activity level, which could only decrease. Also the conditioning took place in a shuttlebox equipped with certain acoustic signals, indicating inhibition of activity, which might have been transferred to the postlearning situation in the home-cage. Consequently, the objective of the present work was to investigate the possibility of recording a home-cage open-field ambulation increase after learning using improved 'Direct correspondence to B. Kvist, Ph.D., Department of Psychology, h o Akademi University, Nunnegatan 4, SF-20500 Finland.
356
B. KVIST & R-K. SELANDER
methods. Ambulation before and after a noiseless maze-learning procedure was recorded in a completely noiseless and nondisturbing home-cage open field to observe an increase in learning-induced ambulation in a familiar environment.
Subjects Ten 9-rno.-old male Swiss albino mice were each housed in a separate open field (see Apparatus). Food and water were available ad libitum until the beginning of the learning procedure, during which access to food was restricted. The testing started at the same hour every afternoon in a room temperature of approximately 23OC. The animals were housed and tested in a windowless room, which was artificially lit. They were kept on a 12 hr light112 hr dark cycle. Apparatus Ten home-cage open fields, each of which consisted of a circular wooden arena (diameter 40 cm) painted white, with a 20-cm high white wall, were used. The arena was covered with 250 g of shavings. The top of the field was covered with a wire net to which a water bottle was attached. During the activity recordings a circular, colorless plastic film (diameter 40 cm) was placed upon the wire net. The plastic film was divided by thin black lines into 19 partitions. A linear 11-point maze (157 x 22 x 18 cm) made of a galvanized iron plate with detachable partitions, was used for the maze learning. Procedure Home-cage openyield ambulation recordings.-Each animal lived undisturbed in its own home-cage open field during a period of five days. The following two days the open-field ambulation of the mice was recorded. To cause minimal disturbance to the mouse during the recording, the water bottle was removed and a plastic film was laid upon the wire net on the top of the field. The film was divided by thin black lines into 19 partitions to aid marlung the track of the animal on a similarly divided map of the film. The recordings were performed in a manner suggested by Broadhurst (1960), that is, by marking how many times an animal moved from one partition to another. Each move indicated an ambulation score and the sum of scores within a 2-min. period indicated the individual ambulation scores of an animal. To obtain a control group, the ambulation scores recorded on two successive days were averaged and the mice divided into two matched groups of five animals each. After the matching procedure the old shavings were replaced by new ones. During the maze-learning period, open-field arnbulation
HOME-CAGE OPEN-FIELD AMBULATION BY MICE
357
recordings were performed twice daily: about five min. before and about 22 min. after the learning period. Maze learning.-The experimental animals ran the maze on six successive days. Error scores and running times were recorded. The animals were given access to standard laboratory pellets for 2 min, in the goal box and for 20 rnin. in 3-1 glass jars, after which they were put into their home-cage open fields and activity was recorded again. The control group was put into an empty plastic trough (38 x 22 x 15 cm) after their ambulation was recorded to spend exactly the same amount of time there as their matched pairs spent in the maze. After this, the control animals were put into glass jars and were given access to standard laboratory pellets for 22 rnin. ad libitum. All animals received approximately 3 g laboratory pellets in their home-cage open field during the night.
RESULTSAND DISCUSSION The maze was almost completely learned in the six days of experimentation. The group mean of the running time diminished significantly (t, = 6.08, p
