The brain undergoes substantial maturation during adolescence, and repeated exposure to ethanol at this time has been shown to result in long-lasting behavioral and neural consequences. During the broad period of adolescence, different neuronal populations and circuits are refined between early and late adolescence, suggesting the possibility that ethanol exposure at these differing times may lead to differential outcomes. The goal of the current study was to evaluate the impact of adolescent intermittent ethanol (AIE) during early and late adolescence on the formation of goal-directed and habitual behavior in adulthood. Male and female Sprague–Dawley rats were exposed to ethanol via intragastric gavage (4.0 g/kg, 25% v/v) every other day from postnatal day (P) 25–45 or P45–65, considered early and late adolescence, respectively. In adulthood (~P70 early or ~ P90 late), rats were gradually food-restricted and began operant training on a fixed ratio 1 schedule. Rats were then transitioned onto random interval schedules and eventually underwent a sensory-specific satiation procedure as a model of reward devaluation. Few differences as a result of adolescent ethanol exposure were found during instrumental training. Following reward devaluation, rats exposed to water and ethanol during early adolescence exhibited reductions in lever pressing, suggestive of a goal-directed response pattern. In contrast, late AIE males and females demonstrated persistent responding following both devalued and non-devalued trials, findings representative of a habitual behavior pattern. The shifts from goal-directed to habitual behavior noted only following late AIE contribute to the growing literature identifying specific behavioral consequences as a result of ethanol exposure during distinct developmental periods within adolescence. More work is needed to determine whether the greater habit formation following late AIE is also associated with elevated habitual ethanol consumption.

大脑在青春期经历了实质性的成熟，此时反复接触乙醇已被证明会导致长期的行为和神经后果。在青春期的广泛时期，不同的神经元群体和回路在青春期早期和晚期之间得到完善，这表明在这些不同时间接触乙醇可能会导致不同的结果。本研究的目的是评估青春期早期和晚期青少年间歇性乙醇 (AIE) 对成年期目标导向和习惯行为形成的影响。雄性和雌性 Sprague-Dawley 大鼠从出生后第 25-45 天或第 45-65 天开始每隔一天通过灌胃（4.0 g/kg，25% v/v）暴露于乙醇，分别考虑青春期早期和晚期. 在成年期（~P70 早期或~P90 晚期），大鼠逐渐限制食物并开始以固定比例 1 的时间表进行操作训练。然后将大鼠转变为随机间隔时间表，并最终接受特定感官的饱足程序作为奖励贬值的模型。在器乐训练期间，几乎没有发现青少年乙醇暴露导致的差异。在奖励贬值之后，在青春期早期暴露于水和乙醇的大鼠表现出杠杆按压的减少，这表明目标导向的反应模式。相比之下，晚期 AIE 男性和女性在贬值和非贬值试验后表现出持续反应，这些发现代表了一种习惯性行为模式。仅在晚期 AIE 之后才注意到的从目标导向到习惯行为的转变有助于越来越多的文献确定青春期不同发育时期乙醇暴露导致的特定行为后果。需要更多的工作来确定晚期 AIE 后更大的习惯​​形成是否也与习惯性乙醇消耗量增加有关。