4 
The pattern of playful defense used during play fighting by male rats (Rattus norvegicus) castrated at birth was compared to that of sham-operated and untreated controls during the juvenile phase and after puberty. The neonatal castrates failed to exhibit the age-related changes in playful defense present in intact male rats of the same age. Following […]
7 
play fighting is often difficult to differentiate from inhibited or immature serious fighting because both may utilize many of the same behavior patterns. In the rat the two behaviors involve different targets of attack. During play fighting, snout or oral contact is directed at the opponent’s nape of the neck, whereas during serious fighting, male […]
7 
Adolescent and adult rats exhibit at least two distinct ultrasonic vocalizations that reflect distinct emotional states. Rats exhibit 22-kHz calls during social defeat, drug withdrawal, as well as in anticipation of aversive events. In contrast, 50-kHz calls are exhibited in high rates during play behavior, mating, as well as in anticipation of rewarding events. The […]
9 
The experience of peer play during the juvenile phase in rats is known to be important for the development of adult social competence. Adult social competence is also compromised by damage to the orbitofrontal cortex (OFC), an area known to be involved in social behavior. We therefore hypothesized that the functioning of the OFC in […]
9 
Studies using laboratory rats have yielded compelling evidence that engaging in social play with peers during the juvenile period is important for the development of a range of skills, including cognitive, emotional, and social ones. In part, these play-induced effects on these skills arise from the developmental effects of play on the maturation of executive […]
10
The effects of radical neonatal decortication on the social play of juvenile rats, as well as the effects of neonatal ablation of frontal or parietal cortex, were examined in this series of experiments. When total decorticates were tested in like-lesioned pairs, the frequency of pinning was reduced by about 50% and their average pin durations […]
5 
Social play of juvenile rats was analyzed following administration of either the serotonin receptor agonist quipazine (1, 2.5, 5 and 10 mg/kg) or the antagonist methysergide at the same doses. Quipazine reduced pinning at all doses, while methysergide did so at only the highest two. An interaction study using the lowest doses of the agents […]
6 
Social play between pairs of individually housed juvenile rats was studied by measuring pinning frequencies occurring during rough-and tumble play. Low doses of morphine increased play, and opioid blockade with naloxone reduced play. Dominance, as measured by which pinned which most, was markedly reduced by naloxone and slightly increased by morphine. These effects were most […]
8 
Social play – that is, play directed toward others – is a readily recognizable feature of childhood. In nonhuman animals, social play, especially seemingly competitive rough-and-tumble play or play fighting, has been the most studied of all forms of play. After several decades of study, researchers of play fighting in laboratory rats have pieced together […]
7
Adult male rats reared as pairmates from weaning were tested in a neutral arena with both members of another pair (one at a time). The unfamiliar pairs were found to engage in play fighting, although they were more likely to escalate the encounter into serious fighting than were pairs of familiar rats. Based on their […]
2
Enucleated juvenile rats were compared to sighted juveniles, and tested over six trials. In some of these trials, the vibrissae were clipped and the test chamber was flooded with white noise. Even though the enucleated rats played, they did so in an atypical manner. They tended to initiate more playful and other social contacts, and […]
4
play fighting by juvenile rats involves playful attacks directed at the partner’s nape, where successful contact leads to gentle rubbing of the snout into the nape area. In addition, the recipient of such contact may defend the nape by adoping tactics of playful defense. The two most common defensive tactics in the juvenile period are […]
10
Although decorticated rats are able to engage in play, their play is abnormal in three ways. First, decorticates do not display the normal, age-related shifts in defensive strategies during development. Second, decorticates do not modify their defensive tactics in response to the social identity of their partners. Third, decorticates display a global shift in defensive […]
8 Fifteen?day?old rats were subjected to one of three housing conditions: mother?and?peer (family), peer, and isolation conditions. At 24 days of age, all subjects were rehoused individually. In Experiment 1, play behaviors were monitored in like?raised pairs. Despite their gross lack of social experience, isolation?reared subjects did not exhibit a deficit in frequencies of rough?and?tumble play. […]
4
Neonatal male rats were either injected subcutaneously with testosterone propionate (TP) or oil vehicle. When weaned, each treated pup was paired with an untreated male sibling. The play fighting of TP?and oil?treated rats were compared at the juvenile phase (30-36 days), and in adulthood (84-90 days). In the juvenile phase, the rate of initiating playful […]
0
The dorsal immobility response (DIR) is typically seen in the infants of many altricial mammalian species. Lifting the animal into the air by the nape of the neck is the primary releasing stimulus. Functionally, this response appears to facilitate carrying of the infants by the adults. When grasped by the nape and lifted into the […]
6 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 […]
8
Early childhood autism is characterized by deficits in social approach and play behaviors, socio-emotional relatedness, and communication/speech abnormalities, as well as repetitive behaviors. These core neuropsychological features of autism can be modeled in laboratory rats, and the results may be useful for drug discovery and therapeutic development. We review data that show that rats selectively […]
6 play fighting in rats is most frequent in the juvenile phase (30-40 days), and then wanes following puberty. During the juvenile phase, the most commonly used defensive tactic to block access to the nape (i.e., the play target) is to rotate around the longitudinal axis to supine. From this position of lying on its back, […]
5
From weaning until sexual maturity, the rates at which young male rats hold each other supine during play fighting appear to become progressively asymmetrical. These changes have been previously thought to reflect an initial lack of dominance and a later development of dominance?subordinance relationships. In this paper it is shown that pairs of male rats […]
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