Corticofugal regulation of predictive coding.
Corticofugal regulation of predictive coding.
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DOI：
10.7554/elife.73289
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发表时间：
2022-03-15
期刊：
影响因子：
7.7
通讯作者：
Geffen MN
中科院分区：
文献类型：
--
作者：
Lesicko AMH;Angeloni CF;Blackwell JM;De Biasi M;Geffen MN
感觉系统必须考虑到背景因素和先前的经验，才能自适应地与动态的外部环境接触。在中枢听觉系统中，神经元根据统计背景调整它们对声音的反应。这些反应调制可以通过分层预测编码透镜来理解：在称为重复抑制的过程中，对重复刺激的反应逐渐减少，而意外刺激产生预测误差信号。预测误差沿听觉层级从下丘(IC)到听觉皮质(AC)递增，提示这些区域可能参与了层级预测编码。自上而下预测线索的一个潜在基础是从AC到皮质下结构的大量下行投射，尽管这个系统在预测处理中的作用从未被直接评估过。我们测试了清醒小鼠听觉皮质-丘脑反馈的光遗传失活对IC神经元对旨在测试预测错误和重复抑制的刺激的反应的影响。皮质-丘脑通路的失活导致IC预测误差的降低。重复抑制不受皮质-丘脑失活的影响，这表明这一指标可能反映了自下而上感觉输入的疲劳，而不是预测性加工。我们还发现IC单位的群体表现出重复增强，即随着刺激重复而放电的顺序增加。皮质-丘脑失活导致中央核团重复增强减少，提示这是一种自上而下的现象。负预测错误是对可预测而不是不可预测序列中的音调的更强反应，在皮质-丘脑失活期间，壳IC单位中的负性预测错误被抑制。预测编码指标的这些变化源于对标准和异常语境的反应中的双向调制，使得IC中的单位在没有皮质输入的情况下对每个语境的反应更相似。我们还研究了麻醉状态和清醒状态之间的这些指标如何比较，通过在两种条件下从相同的单元进行记录。我们发现，预测编码和异常检测的度量因动物的麻醉状态而异，在中央IC出现负预测错误，在没有麻醉的情况下重复增强和预测错误更普遍。总体而言，我们的结果表明，AC通过直接反馈向皮质下大脑区域提供关于声音统计背景的线索，调节预测和重复的处理。
Sensory systems must account for both contextual factors and prior experience to adaptively engage with the dynamic external environment. In the central auditory system, neurons modulate their responses to sounds based on statistical context. These response modulations can be understood through a hierarchical predictive coding lens: responses to repeated stimuli are progressively decreased, in a process known as repetition suppression, whereas unexpected stimuli produce a prediction error signal. Prediction error incrementally increases along the auditory hierarchy from the inferior colliculus (IC) to the auditory cortex (AC), suggesting that these regions may engage in hierarchical predictive coding. A potential substrate for top-down predictive cues is the massive set of descending projections from the AC to subcortical structures, although the role of this system in predictive processing has never been directly assessed. We tested the effect of optogenetic inactivation of the auditory cortico-collicular feedback in awake mice on responses of IC neurons to stimuli designed to test prediction error and repetition suppression. Inactivation of the cortico-collicular pathway led to a decrease in prediction error in IC. Repetition suppression was unaffected by cortico-collicular inactivation, suggesting that this metric may reflect fatigue of bottom-up sensory inputs rather than predictive processing. We also discovered populations of IC units that exhibit repetition enhancement, a sequential increase in firing with stimulus repetition. Cortico-collicular inactivation led to a decrease in repetition enhancement in the central nucleus of IC, suggesting that it is a top-down phenomenon. Negative prediction error, a stronger response to a tone in a predictable rather than unpredictable sequence, was suppressed in shell IC units during cortico-collicular inactivation. These changes in predictive coding metrics arose from bidirectional modulations in the response to the standard and deviant contexts, such that the units in IC responded more similarly to each context in the absence of cortical input. We also investigated how these metrics compare between the anesthetized and awake states by recording from the same units under both conditions. We found that metrics of predictive coding and deviance detection differ depending on the anesthetic state of the animal, with negative prediction error emerging in the central IC and repetition enhancement and prediction error being more prevalent in the absence of anesthesia. Overall, our results demonstrate that the AC provides cues about the statistical context of sound to subcortical brain regions via direct feedback, regulating processing of both prediction and repetition.