The flexible approach hypothesis: unification of effort and cue-responding hypotheses for the role of nucleus accumbens dopamine in the activation of reward-seeking behavior.
The flexible approach hypothesis: unification of effort and cue-responding hypotheses for the role of nucleus accumbens dopamine in the activation of reward-seeking behavior.
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DOI：
10.1523/jneurosci.3958-10.2010
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发表时间：
2010-12-08
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影响因子：
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通讯作者：
Nicola SM
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文献类型：
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作者：
Nicola SM
伏隔核释放的多巴胺被认为有助于做出努力寻求奖励的决定。这一假设得到了以下发现的支持：与需要较少努力的任务相比，需要较高努力程度的任务的执行更容易受到减少伏隔核多巴胺功能的操作的干扰。然而，一些低努力提示响应任务的表现高度依赖于伏隔多巴胺。为了协调这些不同的结果，我们对执行各种操作任务的大鼠进行了详细的行为观察，并确定了将多巴胺受体拮抗剂注射到伏隔核中如何影响动物行为的特定方面。引人注目的是，一旦动物开始一系列操作反应，拮抗剂就不会影响继续该反应链直到奖励交付的能力。相反，当老鼠离开操作区时，拮抗剂会严重损害返回的能力。我们表明，这种损害是特定于动物必须在每次接近场合确定一组新的接近动作的情况；这种行为被称为“灵活做法”。高强度的操作任务和一些低强度的提示响应任务都需要伏隔核中的多巴胺受体激活，因为动物暂停其反应并探索腔室，而伏隔核多巴胺需要通过灵活的操作方法来终止这些暂停。灵活方法假说为理解伏隔核及其多巴胺投射对寻求奖励行为的贡献提供了一个统一的框架。
Dopamine released in the nucleus accumbens is thought to contribute to the decision to exert effort to seek reward. This hypothesis is supported by findings that performance of tasks requiring higher levels of effort is more susceptible to disruption by manipulations that reduce accumbens dopamine function than tasks that require less effort. However, performance of some low effort cue responding tasks is highly dependent on accumbens dopamine. To reconcile these disparate results, we made detailed behavioral observations of rats performing various operant tasks and determined how injection of dopamine receptor antagonists into the accumbens influenced specific aspects of the animals’ behavior. Strikingly, once animals began a chain of operant responses, the antagonists did not affect the ability to continue the chain until reward delivery. Instead, when rats left the operandum, the antagonists severely impaired the ability to return. We show that this impairment is specific to situations in which the animal must determine a new set of approach actions on each approach occasion; this behavior is called “flexible approach.” Both high effort operant tasks and some low effort cue responding tasks require dopamine receptor activation in the accumbens because animals pause their responding and explore the chamber, and accumbens dopamine is required to terminate these pauses with flexible approach to the operandum. The flexible approach hypothesis provides a unified framework for understanding the contribution of the accumbens and its dopamine projection to reward-seeking behavior.