Ernest Gallo Clinic and Research Center, Wheeler Center for the Neurobiology of Addiction, and Department of Neurology, University of California, San Francisco, Emeryville, California 94608, USA.
J Neurosci. 2011 May 4;31(18):6820-30. doi: 10.1523/JNEUROSCI.6491-10.2011.
The nucleus accumbens (NAc) is involved in many reward-related behaviors. The NAc has two major components, the core and the shell. These two areas have different inputs and outputs, suggesting that they contribute differentially to goal-directed behaviors. Using a discriminative stimulus (DS) task in rats and inactivating the NAc by blocking excitatory inputs with glutamate antagonists, we dissociated core and shell contributions to task performance. NAc core but not shell inactivation decreased responding to a reward-predictive cue. In contrast, inactivation of either subregion induced a general behavioral disinhibition. This reveals that the NAc actively suppresses actions inappropriate to the DS task. Importantly, selective inactivation of the shell but not core significantly increased responding to the nonrewarded cue. To determine whether the different contributions of the NAc core and shell depend on the information encoded in their constituent neurons, we performed electrophysiological recording in rats performing the DS task. Although there was no firing pattern unique to either core or shell, the reward-predictive cue elicited more frequent and larger magnitude responses in the NAc core than in the shell. Conversely, more NAc shell neurons selectively responded to the nonrewarded stimulus. These quantitative differences might account for the different behavioral patterns that require either core or shell. Neurons with similar firing patterns could also have different effects on behavior due to their distinct projection targets.
伏隔核（NAc）参与许多与奖励相关的行为。NAc 有两个主要组成部分，核心和壳。这两个区域有不同的输入和输出，这表明它们对目标导向行为有不同的贡献。我们使用大鼠的辨别性刺激（DS）任务，并通过使用谷氨酸拮抗剂阻断兴奋性输入来使 NAc 失活，从而将核心和壳的贡献分离到任务表现中。NAc 核心但不是壳失活减少了对奖励预测线索的反应。相比之下，两个亚区的失活都会导致一般的行为抑制解除。这表明 NAc 积极抑制与 DS 任务不相关的动作。重要的是，壳的选择性失活而不是核心失活显著增加了对无奖励线索的反应。为了确定 NAc 核心和壳的不同贡献是否取决于其组成神经元编码的信息，我们在执行 DS 任务的大鼠中进行了电生理记录。尽管没有独特的核心或壳神经元放电模式，但奖励预测线索在 NAc 核心中比在壳中引起更频繁和更大幅度的反应。相反，更多的 NAc 壳神经元对无奖励刺激有选择性反应。这些定量差异可能解释了需要核心或壳的不同行为模式。具有相似放电模式的神经元也可能由于其不同的投射目标而对行为产生不同的影响。
