Department of Psychology, University of Toronto Mississauga, 3359 Mississauga Rd N., Mississauga, ON L5L 1C6, Canada.
Behav Brain Res. 2011 Jun 20;220(1):91-9. doi: 10.1016/j.bbr.2011.01.033. Epub 2011 Jan 26.
The mechanisms by which childhood abuse and/or neglect become risk factors for the development of drug addiction, problem gambling, and other disorders of behavioral inhibition are unknown. The loss of behavioral inhibition is often triggered by reward-related cues that acquire incentive salience. This study examined whether inadequate early-life social experience in rats affects the incentive salience of reward-related cues. Rats were deprived of early-life social experience with the mother and litter through artificial-rearing (AR). A group of AR rats (AR+STM) received additional tactile stimulation that mimicked maternal licking, a critical component of rat maternal care. Control rats were maternally reared (MR). The incentive salience attributed to a food cue was measured in adult rats using a conditioned approach task, where a conditional stimulus (CS; lever) was paired with food delivery, and in a conditional reinforcement task. The dependent measures were approach towards the CS (sign-tracking) versus approach towards the place of food delivery (goal-tracking) and instrumental responding for the CS. AR rats made significantly more sign-tracking responses than MR rats. AR rats also made more instrumental responses when reinforced with the CS. AR+STM rats' responses were intermediate to MR and AR rats. Thus, inadequate early-life social experience enhanced the incentive salience of a reward-related cue in adulthood. Replacement of maternal licking partially reversed this effect. These results highlight a potential link between early-life social adversity and susceptibility to disorders of behavioral inhibition.
童年期虐待和/或忽视成为药物成瘾、问题赌博和其他行为抑制障碍发展的风险因素的机制尚不清楚。行为抑制的丧失通常是由获得激励显著性的与奖励相关的线索引发的。本研究探讨了大鼠早期生活中缺乏社会经验是否会影响与奖励相关的线索的激励显著性。通过人工饲养（AR）剥夺了大鼠早期的母婴和同窝社会体验。一组 AR 大鼠（AR+STM）接受了额外的触觉刺激，模拟了母鼠的舔舐，这是大鼠母性照顾的关键组成部分。对照大鼠进行了母婴饲养（MR）。使用条件接近任务测量成年大鼠对食物线索的激励显著性，其中条件刺激（CS；杠杆）与食物传递配对，以及在条件强化任务中。依赖措施是对 CS 的接近（标记跟踪）与对食物传递位置的接近（目标跟踪）以及对 CS 的工具反应。AR 大鼠比 MR 大鼠做出了更多的标记跟踪反应。用 CS 强化时，AR 大鼠也做出了更多的工具反应。AR+STM 大鼠的反应介于 MR 和 AR 大鼠之间。因此，早期生活中的社会经验不足会增强成年后与奖励相关的线索的激励显著性。对母鼠舔舐的替代部分逆转了这种效应。这些结果强调了早期生活中的社会逆境与行为抑制障碍易感性之间的潜在联系。
