Ear Institute, University College London, London, UK.
Ear Institute, University College London, London, UK.
Cortex. 2018 Dec;109:92-103. doi: 10.1016/j.cortex.2018.08.032. Epub 2018 Sep 14.
The brain draws on knowledge of statistical structure in the environment to facilitate detection of new events. Understanding the nature of this representation is a key challenge in sensory neuroscience. Specifically, it is unknown whether real-time perception of rapidly-unfolding sensory signals is driven by a coarse or detailed representation of the proximal stimulus history. We recorded electroencephalography brain responses to frequency outliers in regularly-patterned (REG) versus random (RAND) tone-pip sequences which were generated anew on each trial. REG and RAND sequences were matched in frequency content and span, only differing in the specific order of the tone-pips. Stimuli were very rapid, limiting conscious reasoning in favour of automatic processing of regularity. Listeners were naïve and performed an incidental visual task. Outliers within REG evoked a larger response than matched outliers in RAND. These effects arose rapidly (within 80 msec) and were underpinned by distinct sources from those classically associated with frequency-based deviance detection. These findings are consistent with the notion that the brain continually maintains a detailed representation of ongoing sensory input and that this representation shapes the processing of incoming information. Predominantly auditory-cortical sources code for frequency deviance whilst frontal sources are associated with tracking more complex sequence structure.
大脑利用环境中统计结构的知识来促进新事件的检测。理解这种表示的本质是感觉神经科学的一个关键挑战。具体来说，尚不清楚实时感知快速展开的感觉信号是由近端刺激历史的粗略表示还是详细表示驱动的。我们记录了脑电图对规则（REG）与随机（RAND）音调序列中频率异常值的脑反应，这些序列在每次试验中都是新生成的。REG 和 RAND 序列在频率内容和跨度上匹配，仅在音调的具体顺序上有所不同。刺激非常快，限制了有意识的推理，有利于自动处理规律性。听众是天真的，执行附带的视觉任务。REG 中的异常值比 RAND 中匹配的异常值引起更大的反应。这些效应在 80 毫秒内迅速出现，并且由与经典的基于频率偏差检测相关的来源不同的来源支持。这些发现与大脑不断保持对正在进行的感觉输入的详细表示的概念一致，并且这种表示塑造了传入信息的处理。主要的听觉皮质源对频率偏差进行编码，而额叶源则与跟踪更复杂的序列结构有关。
