Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260, USA.
Proc Natl Acad Sci U S A. 2012 Jan 31;109(5):1719-24. doi: 10.1073/pnas.1114137109. Epub 2012 Jan 17.
Adolescents often respond differently than adults to the same salient motivating contexts, such as peer interactions and pleasurable stimuli. Delineating the neural processing differences of adolescents is critical to understanding this phenomenon, as well as the bases of serious behavioral and psychiatric vulnerabilities, such as drug abuse, mood disorders, and schizophrenia. We believe that age-related changes in the ways salient stimuli are processed in key brain regions could underlie the unique predilections and vulnerabilities of adolescence. Because motivated behavior is the central issue, it is critical that age-related comparisons of brain activity be undertaken during motivational contexts. We compared single-unit activity and local field potentials in the nucleus accumbens (NAc) and dorsal striatum (DS) of adolescent and adult rats during a reward-motivated instrumental task. These regions are involved in motivated learning, reward processing, and action selection. We report adolescent neural processing differences in the DS, a region generally associated more with learning than reward processing in adults. Specifically, adolescents, but not adults, had a large proportion of neurons in the DS that activated in anticipation of reward. More similar response patterns were observed in NAc of the two age groups. DS single-unit activity differences were found despite similar local field potential oscillations. This study demonstrates that in adolescents, a region critically involved in learning and habit formation is highly responsive to reward. It thus suggests a mechanism for how rewards might shape adolescent behavior differently, and for their increased vulnerabilities to affective disorders.
青少年对相同显著激励背景（如同伴互动和愉悦刺激）的反应往往与成年人不同。描绘青少年神经处理差异对于理解这一现象以及药物滥用、情绪障碍和精神分裂症等严重行为和精神脆弱的基础至关重要。我们认为，在关键大脑区域中显著刺激的处理方式与年龄相关的变化可能是青少年独特偏好和脆弱性的基础。由于动机行为是核心问题，因此在激励背景下进行与年龄相关的大脑活动比较至关重要。我们比较了在奖励动机工具任务期间青少年和成年大鼠伏隔核（NAc）和背侧纹状体（DS）中的单个单元活动和局部场电位。这些区域参与动机学习、奖励处理和动作选择。我们报告了 DS 中青少年神经处理的差异，DS 通常与成年人的奖励处理相比，更多地与学习相关。具体来说，青少年，而不是成年人，有很大比例的 DS 神经元在奖励预期时激活。在两个年龄组的 NAc 中观察到更相似的反应模式。尽管局部场电位振荡相似，但仍发现 DS 的单单元活动差异。这项研究表明，在青少年中，一个与学习和习惯形成密切相关的区域对奖励高度敏感。因此，它为奖励如何以不同的方式塑造青少年行为以及他们对情感障碍的易感性提供了一种机制。
