The possibility that asphyxia may influence social processes was evaluated in two experiments. In the first, juvenile rats were asphyxiated and their play behavior (as measured by pins and dorsal contacts) was measured immediately and 30 min following recovery. Although the asphyxiated rats’ play was substantially reduced immediately following recovery, they exhibited no play changes […]
Juvenile play experiences promote behavioral flexibility in rats. If other early positive experiences, such as tactile stimulation, are given prior to exposure to psychostimulants, the behavioral response to the drug is attenuated. The objective of the present study was to determine if the experience of juvenile play behavior would attenuate the response to nicotine. Two […]
A cataleptic animal clings in a vertical position, unmoving, for abnormally long periods by supporting some of its weight on its hindlegs, grasping with the forepaws, flexing its forelimbs, and holding the head horizontal. When the head is snugly wrapped with a bandage, the head slowly falls backward, the neck hyperextends, the forelimbs extend and […]
A potent convulsant, trimethylolpropane phosphate (TMPP), was evaluated for long-term effects on measures of social behaviors and anxiety in Long- Evans rats. Animals received three to four daily treatments of TMPP (0.1 mg/kg/ml) beginning at age 23 days in Experiment 1 and 73 days in Experiment 2. Gregariousness was measured in juvenile play and adult […]
Previously it was found that during the loss of postural support induced by combined administration of haloperidol and morphine, rats became markedly hypothermic. The present work was a more detailed study of this hypothermia. Morphine alone (20 mg/kg) produced a slight hyperthermia (1∞C) in female rats and no effect in males. Haloperidol alone (5 mg/kg) […]
Juvenile male rats frequently play more than female rats, but the presence of sex differences is affected by testing conditions and may also depend on the strain of rat. In this experiment, we tested play and defensive behaviors in male and female Long-Evans, Sprague-Dawley, and Wistar rats. When observed with a cage mate during the […]
Differences in the play behavior of 2 strains of rats suggest that different components of play fighting can be modified independently. The development of play fighting in cross-strain pairs of familiar and unfamiliar rats was examined to determine whether interacting with a noncongruent pairmate would alter the pattern of play typical for each strain. In […]
Bouts of pelage cleaning can be readily evoked in laboratory rodents under conditions of exposure to novelty. Such novelty-induced grooming is described as stereotyped and rostro-caudal in its progression. The patterned structure of novelty-induced grooming makes it particularly attractive for research on the organizational and motivational underpinnings of co-ordinated behaviour. Micro-characteristics of stereotyped novelty-induced grooming […]
Dead reckoning is an on-line form of spatial navigation used by an animal to identify its present location and return directly to a starting location, even after circuitous outward trips. At present, it is not known which of several self-movement cues (efferent copy from movement commands, proprioceptive information, sensory flow, or vestibular information) are used […]
This study investigated the effect of postnatal tactile stimulation (TS) on juvenile behavior, adult amphetamine (AMPH) sensitization, and the interaction of TS and AMPH on prefrontal cortical (PFC) thickness and striatum size. Pups received TS by stroking daily with a feather duster from birth till weaning and were tested, as juveniles, in behavioral tasks including […]
When playing, rats emit 50-kHz calls which may function as play signals. A previous study using devocalized rats provides support for the hypothesis that 50-kHz function to promote and maintain playful interactions (Kisko et al., 2015). However, in that study, all pairs were cage mates and familiar with each other’s playful tendencies that could have […]
Play involves neural circuits that encompass motivational, emotional and reward systems, such that the removal of the cortex does not impair the development, frequency, form or reward value of playing. However, the ability to ‘play with play’, that is, the ability to modify how play is performed with changing salient features of the context, does […]
The evidence that frequency modulated (FM) 50 kHz ultrasonic vocalizations (USVs) reflect a positive emotional state in rats is reviewed. Positive emotional states in humans are measured by facial-vocal displays (e.g., Duchenne smiling and laughter), approach behavior, and subjective self-report of feeling states. In laboratory animals, only facial-vocal displays, along with approach behavior can be […]
To the best of our knowledge, the basic biological values of all mammalian brains were built upon the same basic plan, laid out in consciousness-creating affective circuits that are concentrated in subcortical regions, far below the neocortical “thinking cap ” that is so highly developed in humans. Mental life would be impossible without this foundation. […]
Juvenile rats sustaining dopamine depletions by intraventricular injections of 6-hydroxydopamine (6-OHDA) as neonates were used to study the role of the striatum in controlling play fighting. As juveniles, the rats exhibited all the behavior elements typical of play fighting. However, they were more likely to use defensive tactics that shortened the playful contact between partners; […]
Can animal models provide insights into human empathy and promote nurturance? There is a growing recognition of how animals respond to the affective states of other animals (1, 2), including the show of empathy, a state once thought to be unique to primates. On page 1427 of this issue, Ben-Ami Bartal et al. (3) demonstrate […]
Rats reared with playful peers during the juvenile period have a modified prefrontal cortex and improved executive functions, whereas ones reared with less playful partners, such as an adult, do not. It has been hypothesized that peer-peer play fighting creates unique experiences that tax executive functions and so influence the refinement of the prefrontal cortex. […]
Ultrasonic vocalizations (USV) are widely studied in mice and rats, and in case of rats, the bulk of empirical evidence is based on outbred rats, which in most studies belong to either Long Evans, Sprague-Dawley or Wistar stocks. It is known that these stocks can differ in terms of specific brain variables and also behaviorally, […]
In the traditional model for sexual differentiation in mammals, the female phenotype is the default condition. That is, the female-typical pattern will persist unless acted upon by hormones early in development. The frequency of play fighting in rats, as in most other mammals, is sexually differentiated, and conforms to the traditional model. Males engage in […]
Whether it is that animals are young so that they can play, or whether it is that they play because they are young, play should be more prevalent in species that have a greater degree of postnatal development. This hypothesis is tested by comparative analyses within two mammalian orders (primates and muroid rodents) using independent […]
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