Pellis S M, McKenna M
Department of Psychology, University of Lethbridge, Alta., Canada.
Behav Brain Res. 1995 Apr;68(1):65-73. doi: 10.1016/0166-4328(94)00161-8.
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 adopting tactics of playful defense. The two most common defensive tactics in the juvenile period are evasion, where the recipient swerves or leaps away and facing defense involving rotation to supine, where the attacker is faced and its further attempts to contact the nape are blocked. An unresolved issue is whether the nape contact itself or defense by the recipient alone or in combination with nape contact, are involved in rewarding play fighting. In this study, drug-induced non-playful partners were used to test the 'motivation' for play fighting when only playful nape contact was possible. In drug-trials compared to baseline and saline trials, both neonatally androgenized females (high players) and control, oil-treated, females (low players), decreased the frequency of launching nape attacks. These results suggest that nape contact alone, in the absence of defense by the recipient, is not sufficient reinforcement for such playful activity, irrespective of the initial playfulness of the subjects. However, while nape attacks decrease, other forms of social contact, such as anogenital investigation and climbing over the partner (i.e., crawl overs), increase in frequency. These results suggest that non-playful partners are not neutral targets for normal rats. Rather, the 'non-normal' behavior of the drugged target may affect the subjects' behavior in such a way as to reduce their playfulness for reasons other than reduced reinforcement for play.
幼年大鼠的嬉戏打斗包括对伙伴颈部的嬉戏性攻击，成功接触会导致用鼻子轻轻摩擦颈部区域。此外，这种接触的接受者可能会采取嬉戏性防御策略来保护颈部。幼年时期最常见的两种防御策略是躲避，即接受者突然转向或跳开；以及面对防御，即翻身仰卧，面对攻击者，阻止其进一步接触颈部。一个尚未解决的问题是，颈部接触本身、接受者单独的防御或者与颈部接触相结合，是否参与了对嬉戏打斗的奖励。在这项研究中，使用药物诱导的非嬉戏性伙伴来测试当仅可能进行嬉戏性颈部接触时嬉戏打斗的“动机”。与基线试验和生理盐水试验相比，在药物试验中，新生期雄激素化的雌性大鼠（嬉戏频率高）和对照组经油处理的雌性大鼠（嬉戏频率低）都降低了发起颈部攻击的频率。这些结果表明，在没有接受者防御的情况下，仅颈部接触不足以强化这种嬉戏活动，无论实验对象最初的嬉戏程度如何。然而，虽然颈部攻击减少了，但其他形式的社交接触，如肛门生殖器检查和爬过伙伴（即爬跨），频率却增加了。这些结果表明，非嬉戏性伙伴对正常大鼠来说并非中立目标。相反，药物处理对象的“非正常”行为可能会以某种方式影响实验对象的行为，从而降低它们的嬉戏性，其原因并非嬉戏强化减少。
