Melbourne School of Psychological Sciences, The University of Melbourne, Parkville, Victoria 3010, Australia.
J Neurosci. 2012 Sep 5;32(36):12488-98. doi: 10.1523/JNEUROSCI.1708-12.2012.
Perceptual decision making is believed to be driven by the accumulation of sensory evidence following stimulus encoding. More controversially, some studies report that neural activity preceding the stimulus also affects the decision process. We used a multivariate pattern classification approach for the analysis of the human electroencephalogram (EEG) to decode choice outcomes in a perceptual decision task from spatially and temporally distributed patterns of brain signals. When stimuli provided discriminative information, choice outcomes were predicted by neural activity following stimulus encoding; when stimuli provided no discriminative information, choice outcomes were predicted by neural activity preceding the stimulus. Moreover, in the absence of discriminative information, the recent choice history primed the choices on subsequent trials. A diffusion model fitted to the choice probabilities and response time distributions showed that the starting point of the evidence accumulation process was shifted toward the previous choice, consistent with the hypothesis that choice priming biases the accumulation process toward a decision boundary. This bias is reflected in prestimulus brain activity, which, in turn, becomes predictive of future decisions. Our results provide a model of how non-stimulus-driven decision making in humans could be accomplished on a neural level.
感知决策被认为是在刺激编码后，根据感官证据的积累来驱动的。更有争议的是，一些研究报告称，刺激前的神经活动也会影响决策过程。我们使用多变量模式分类方法来分析人类脑电图 (EEG)，从空间和时间分布的脑信号模式中解码感知决策任务中的选择结果。当刺激提供了可区分的信息时，选择结果可以通过刺激编码后的神经活动来预测；当刺激没有提供可区分的信息时，选择结果可以通过刺激前的神经活动来预测。此外，在没有可区分信息的情况下，最近的选择历史会在随后的试验中启动选择。拟合到选择概率和反应时间分布的扩散模型表明，证据积累过程的起点向先前的选择转移，这与选择启动会使积累过程偏向决策边界的假设一致。这种偏差反映在刺激前的大脑活动中，而刺激前的大脑活动反过来又可以预测未来的决策。我们的结果提供了一个模型，说明人类如何在神经水平上完成非刺激驱动的决策。
