School of Psychology, University of Newcastle, Newcastle, Australia.
School of Psychology, University of Newcastle, Newcastle, Australia.
Neuroscience. 2018 Oct 1;389:41-53. doi: 10.1016/j.neuroscience.2018.05.011. Epub 2018 May 19.
This paper features two studies confirming a lasting impact of first learning on how subsequent experience is weighted in early relevance-filtering processes. In both studies participants were exposed to sequences of sound that contained a regular pattern on two different timescales. Regular patterning in sound is readily detected by the auditory system and used to form "prediction models" that define the most likely properties of sound to be encountered in a given context. The presence and strength of these prediction models is inferred from changes in automatically elicited components of auditory evoked potentials. Both studies employed sound sequences that contained both a local and longer-term pattern. The local pattern was defined by a regular repeating pure tone occasionally interrupted by a rare deviating tone (p=0.125) that was physically different (a 30msvs. 60ms duration difference in one condition and a 1000Hz vs. 1500Hz frequency difference in the other). The longer-term pattern was defined by the rate at which the two tones alternated probabilities (i.e., the tone that was first rare became common and the tone that was first common became rare). There was no task related to the tones and participants were asked to ignore them while focussing attention on a movie with subtitles. Auditory-evoked potentials revealed long lasting modulatory influences based on whether the tone was initially encountered as rare and unpredictable or common and predictable. The results are interpreted as evidence that probability (or indeed predictability) assigns a differential information-value to the two tones that in turn affects the extent to which prediction models are updated and imposed. These effects are exposed for both common and rare occurrences of the tones. The studies contribute to a body of work that reveals that probabilistic information is not faithfully represented in these early evoked potentials and instead exposes that predictability (or conversely uncertainty) may trigger value-based learning modulations even in task-irrelevant incidental learning.
本文有两项研究证实，初次学习对早期相关性过滤过程中后续经验的权重具有持久影响。在这两项研究中，参与者都接触到包含两种不同时间尺度规则模式的声音序列。听觉系统可以很容易地检测到声音中的规则模式，并利用这些规则模式形成“预测模型”，定义在给定情境中最有可能出现的声音特征。这些预测模型的存在和强度是通过听觉诱发电位自动引出的成分变化来推断的。这两项研究都使用了包含局部和长期模式的声音序列。局部模式由一个规则重复的纯音定义，偶尔会被一个罕见的偏离音打断（在一种情况下，p=0.125；在另一种情况下，一个是 30ms，另一个是 60ms），其物理性质不同（在一种情况下，一个是 1000Hz，另一个是 1500Hz）。长期模式由两种音调交替概率的速率定义（即，最初罕见的音调变得常见，而最初常见的音调变得罕见）。这些音调没有与任务相关的关系，参与者被要求在观看带有字幕的电影时忽略它们，将注意力集中在电影上。听觉诱发电位揭示了基于音调最初是罕见和不可预测还是常见和可预测而产生的持久调制影响。结果被解释为证据，即概率（或可预测性）为两个音调赋予了不同的信息值，从而影响了预测模型的更新和施加程度。这些影响在音调的常见和罕见出现时都存在。这些研究为揭示概率信息在这些早期诱发电位中没有被忠实表示的工作提供了补充，而是暴露了可预测性（或者相反的不确定性）即使在与任务无关的偶然学习中，也可能触发基于价值的学习调制。
