Influence of uncertainty and surprise on human corticospinal excitability during preparation for action
Influence of uncertainty and surprise on human corticospinal excitability during preparation for action
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DOI：
10.1016/j.cub.2008.04.051
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发表时间：
2008-05-20
期刊：
影响因子：
9.2
通讯作者：
Rothwell, John C.
中科院分区：
文献类型：
--
作者：
Bestmann, Sven;Harrison, Lee M.;Rothwell, John C.
行动是由先验的感官信息引导的[1-10]，这本身就是不确定的。然而，运动系统是如何通过当前感官信息的反复试验内容来塑造的，这在很大程度上仍未被探索。先前的研究表明，在特定情境下学习到的条件概率，可以用来预先影响运动系统的输出[11-14]。为了验证这一点，我们使用经颅磁刺激（TMS）来读取指令延迟任务中准备行动时的皮质脊髓兴奋性（CSE）[15,16]。我们系统地通过改变指导性视觉线索的有效性来改变即将发生的行动的不确定性。我们在逐个试验的基础上使用两个信息论量来预测行动之前CSE的变化：熵（平均不确定性）和惊喜（视觉线索传达的刺激绑定信息）[17-19]。我们的数据表明，在行动准备过程中，人类的CSE根据指导行动的视觉事件所传达的熵和惊喜而变化。对于即将发生的行动和事件传达的低惊喜的低熵试验，CSE增加。在反应时间上观察到相应的影响。我们认为，运动输出是根据大脑中动态表示的上下文概率而有偏差的。
Actions are guided by prior sensory information [1-10], which is inherently uncertain. However, how the motor system is sculpted by trial-by-trial content of current sensory information remains largely unexplored. Previous work suggests that conditional probabilities, learned under a particular context, can be used preemptively to influence the output of the motor system [11-14]. To test this we used transcranial magnetic stimulation (TMS) to read out corticospinal excitability (CSE) during preparation for action in an instructed delay task [15,16]. We systematically varied the uncertainty about an impending action by changing the validity of the instructive visual cue. We used two information-theoretic quantities to predict changes in CSE, prior to action, on a trial-by-trial basis: entropy (average uncertainty) and surprise (the stimulus-bound information conveyed by a visual cue) [17-19]. Our data show that during preparation for action, human CSE varies according to the entropy and surprise conveyed by visual events guiding action. CSE increases on trials with low entropy about the impending action and low surprise conveyed by an event. Commensurate effects were observed in reaction times. We suggest that motor output is biased according to contextual probabilities that are represented dynamically in the brain.