Sturman David A, Mandell Daniel R, Moghaddam Bita
Department of Neuroscience.
Behav Neurosci. 2010 Feb;124(1):16-25. doi: 10.1037/a0018463.
Adolescence is associated with the development of brain regions linked to cognition and emotion. Such changes are thought to contribute to the behavioral and neuropsychiatric vulnerabilities of this period. We compared adolescent (Postnatal Days 28-42) and adult (Postnatal Day 60+) rats as they performed a simple instrumental task and extinction. Rats were trained to poke into a hole for a food-pellet reinforcer. After six days of training, rats underwent extinction sessions in which the previously rewarded behavior was no longer reinforced. During extinction, we examined the effects of continued presentation of a cue light and food restriction. Adults and adolescents exhibited similar performance during training, although adolescents made more task-irrelevant pokes, consistent with increased exploration. Adults made more premature pokes, which could indicate a more exclusive focus on the task. During extinction, adolescents made more perseverative (previously reinforced) pokes than adults. This behavior was strongly modulated by the combination of motivational factors present (food restriction and cue light), indicating that adolescents were differentially sensitive to them. Furthermore, food restriction induced greater open-field activity in adolescents but not in adults. Thus, as the neural circuitry of motivated behavior develops substantially during adolescence, so too does the behavioral sensitivity to motivational factors. Understanding how such factors differently affect adolescents may shed light on mechanisms that lead to the development of disorders that are manifested during this period.
青春期与与认知和情感相关的脑区发育有关。这种变化被认为是导致这一时期行为和神经精神易损性的原因。我们比较了青春期（出生后第28 - 42天）和成年（出生后第60天及以上）大鼠在执行简单工具性任务和消退过程中的表现。大鼠被训练戳进一个洞以获取食物颗粒强化物。经过六天的训练后，大鼠进入消退阶段，在此期间先前得到奖励的行为不再得到强化。在消退过程中，我们研究了持续呈现提示灯和食物限制的影响。成年大鼠和青春期大鼠在训练期间表现出相似的行为，尽管青春期大鼠做出了更多与任务无关的戳刺动作，这与探索行为增加一致。成年大鼠做出了更多过早的戳刺动作，这可能表明它们对任务的专注度更高。在消退过程中，青春期大鼠比成年大鼠做出了更多持续性（先前得到强化的）戳刺动作。这种行为受到当前存在的动机因素（食物限制和提示灯）组合的强烈调节，表明青春期大鼠对这些因素的敏感性不同。此外，食物限制在青春期大鼠中诱导出更大的旷场活动，但在成年大鼠中没有。因此，随着动机行为的神经回路在青春期大量发育，对动机因素的行为敏感性也在增加。了解这些因素如何不同地影响青春期大鼠可能有助于揭示导致在此期间出现的疾病发展的机制。
