ABSTRACT

Actions are guided by a combination of external cues, internal intentions, and stored knowledge. Self-initiated voluntary actions, produced without immediate external cues, may be preceded by a slow EEG Readiness Potential (RP) that progressively increases prior to action. The cognitive significance of this neural event is controversial. Some accounts link the RP to the fact that timing of voluntary actions is generated endogenously, without external constraints. Others link it to the unique role of a planning process, and therefore of temporal expectation, in voluntary actions. In many previous experiments, actions are unconstrained by external cues, but also potentially involve preplanning and anticipation. To separate these factors, we developed a reinforcement learning paradigm where participants learned, through trial and error, the optimal time to act. If the RP reflects freedom from external constraint, its amplitude should be greater early in learning, when participants do not yet know when to act. Conversely, if the RP reflects planning, it should be greater later on, when participants have learned, and plan in advance, the time of action. We found that RP amplitudes grew with learning, suggesting that this neural activity reflects planning and anticipation for the forthcoming action, rather than freedom from external constraint.

摘要

行动由外部线索、内部意图和存储知识的组合指导。自发的自愿行动， 在没有直接外部线索的情况下产生的，可能会出现缓慢的 EEG 准备电位 (RP)，该电位在行动之前逐渐增加。这种神经事件的认知意义是有争议的。一些帐户将 RP 与以下事实联系起来，即自愿行动的时间是内生的，没有外部约束。其他人将其与计划过程的独特作用联系起来，因此与自愿行动中的时间期望有关。在之前的许多实验中，行动不受外部线索的约束，但也可能涉及预先计划和预期。为了分离这些因素，我们开发了一种强化学习范式，参与者通过反复试验来学习最佳行动时间。如果 RP 反映了不受外部约束的影响，则在学习早期其幅度应该更大，当参与者还不知道何时采取行动时。相反，如果 RP 反映了计划，那么当参与者已经了解并提前计划行动时间时，它应该更大。我们发现 RP 振幅随着学习而增长，这表明这种神经活动反映了对即将发生的行动的计划和预期，而不是不受外部约束的影响。