Center for Studies in Behavioral Neurobiology, Department of Psychology, Concordia University, 7141 Sherbrooke W., Montreal, QC, H4B 1R6, Canada.
Arch Sex Behav. 2012 Feb;41(1):31-62. doi: 10.1007/s10508-012-9935-5.
Although sexual behavior is controlled by hormonal and neurochemical actions in the brain, sexual experience induces a degree of plasticity that allows animals to form instrumental and Pavlovian associations that predict sexual outcomes, thereby directing the strength of sexual responding. This review describes how experience with sexual reward strengthens the development of sexual behavior and induces sexually-conditioned place and partner preferences in rats. In both male and female rats, early sexual experience with partners scented with a neutral or even noxious odor induces a preference for scented partners in subsequent choice tests. Those preferences can also be induced by injections of morphine or oxytocin paired with a male rat's first exposure to scented females, indicating that pharmacological activation of opioid or oxytocin receptors can "stand in" for the sexual reward-related neurochemical processes normally activated by sexual stimulation. Conversely, conditioned place or partner preferences can be blocked by the opioid receptor antagonist naloxone. A somatosensory cue (a rodent jacket) paired with sexual reward comes to elicit sexual arousal in male rats, such that paired rats with the jacket off show dramatic copulatory deficits. We propose that endogenous opioid activation forms the basis of sexual reward, which also sensitizes hypothalamic and mesolimbic dopamine systems in the presence of cues that predict sexual reward. Those systems act to focus attention on, and activate goal-directed behavior toward, reward-related stimuli. Thus, a critical period exists during an individual's early sexual experience that creates a "love map" or Gestalt of features, movements, feelings, and interpersonal interactions associated with sexual reward.
尽管性行为受到大脑中的激素和神经化学作用的控制，但性体验会引起一定程度的可塑性，使动物能够形成预测性结果的工具性和条件反射性关联，从而指导性行为的强度。这篇综述描述了性体验如何增强性行为的发展，并在大鼠中诱导性条件化的位置和伴侣偏好。在雄性和雌性大鼠中，早期与带有中性甚至有害气味的伴侣进行性体验会导致在随后的选择测试中对有气味的伴侣产生偏好。这些偏好也可以通过与雄性大鼠首次接触有气味的雌性大鼠配对的吗啡或催产素注射来诱导，表明阿片类或催产素受体的药理学激活可以“替代”正常由性刺激激活的与性奖励相关的神经化学过程。相反，条件化的位置或伴侣偏好可以被阿片受体拮抗剂纳洛酮阻断。与性奖励相关的躯体感觉线索（啮齿动物夹克）会引起雄性大鼠的性唤起，以至于没有夹克的配对大鼠会出现明显的交配缺陷。我们提出，内源性阿片类激活是性奖励的基础，它还会在预测性奖励的线索存在下敏化下丘脑和中脑边缘多巴胺系统。这些系统作用于将注意力集中在与性奖励相关的刺激上，并激活针对这些刺激的目标导向行为。因此，个体早期性体验期间存在一个关键时期，会形成与性奖励相关的特征、运动、感觉和人际互动的“爱情地图”或整体印象。
