INTERRUPTED ONGOING BEHAVIOUR IN 2 SPECIES OF VOLE (MICROTUS AGRESTIS AND CLETHRIONOMYS BRITANNICUS) .2. EXTENDED ANALYSIS OF MOTIVATIONAL VARIABLES UNDERLYING FLEEING AND GROOMING BEHAVIOUR

Experiments were designed to examine two previously proposed variables: (a) an 'activity tendency' which results in increased probability of fleeing; (b) an 'optimal arousal' range in which grooming is most likely to occur. Wild-trapped Microtus agrestis and Clethrionomys britannicus were individually housed and tested in the previously employed experimental alley. The probability of fleeing behaviour was greatly increased when overt locomotion was either concurrent with or ceased within 10 sec of the experimental disturbance. The concept of a temporarily persisting 'activity tendency' which in itself affects fleeing was supported. Amphetamine increased fleeing and Nembutal decreased fleeing to an extent that could not be accounted for solely in terms of current or recently ceased locomotion. Differences between species and cover conditions were equivocal, perhaps due to the high tendency of individually housed animals to flee. Two main techniques for studying the previously defined 'optimal arousal' model for grooming were (1) to examine integration of home pen cover plus amphetamine and Nembutal with species differences in grooming, (2) attempt to manipulate 'arousal' over a wide range with the two drugs. Cover and 0·8 mg per kg amphetamine produced more grooming in Microtus while no cover and 15 mg per kg Nembutal produced more grooming in Clethrionomys, as predicted from the 'arousal' model. Further, the drug and cover inputs combined in their effect. Each species showed an overall non-linear relationship between drug dose and grooming as expected from the model. Certain inconsistencies with the model were also noted in the present experiments, however, and the possibility that both 'arousal' and 'conflict' models are necessary is discussed. The increase in grooming intensity was again noted, particularly under amphetamine, as was the increased probability and vigour of other simple motor patterns with this drug. Problems of integration of multiple inputs with patterned outputs are discussed further. © 1968.