Interactions between rhythmic and feature predictions to create parallel time-content associations

The brain is inherently proactive, constantly predicting the when (moment) and what (content) of future input in order to optimize information processing. Previous research on such predictions has mainly studied the ‘when’ or ‘what’ domain separately, missing to investigate the potential integration of both types of predictive information. In the absence of such integration, temporal cues are assumed to enhance any upcoming content at the predicted moment in time (general temporal predictor). However, if the when and what prediction domain were integrated, a much more flexible neural mechanism may be proposed in which temporal-feature interactions would allow for the creation of multiple concurrent time-content predictions (parallel time-content predictor). Here, we used a temporal association paradigm in two experiments in which sound identity was systematically paired with a specific time delay after the offset of a rhythmic visual input stream. In Experiment 1, we revealed that participants associated the time delay of presentation with the identity of the sound. In Experiment 2, we unexpectedly found that the strength of this temporal association was negatively related to the EEG steady-state evoked responses (SSVEP) in preceding trials, showing that after high neuronal responses participants responded inconsistent with the time-content associations, similar to adaptation mechanisms. In this experiment, time-content associations were only present for low SSVEP responses in previous trials. These results tentatively show that it is possible to represent multiple time-content paired predictions in parallel, however future 32 research is needed to investigate this interaction further.

大脑天生具备前瞻性加工特性，会持续预测未来输入信息的时机与内容，以此优化信息处理效率。既往针对此类预测机制的研究大多仅单独探讨“时机”或“内容”单一维度，未能同时考察两类预测信息的潜在整合路径。若缺乏此类整合，时间线索通常会在预测时刻对所有即将到来的内容信息产生增强效应（通用时间预测机制）。而若将时机与内容预测维度进行整合，则可提出更为灵活的神经机制：时间-特征交互作用能够支持生成多项并发的时间-内容预测（并行时间-内容预测机制）。

本研究通过两项实验采用时间关联范式，将声音身份与节律性视觉输入流偏移后的特定延迟时间进行系统配对。实验1结果显示，被试能够将刺激呈现的延迟时间与声音身份建立稳定关联。实验2中我们意外发现，该时间关联的强度与前一试次的脑电稳态诱发电位（steady-state evoked responses, SSVEP）呈负相关：即当神经元反应水平较高时，被试的行为表现与时间-内容关联不符，这一现象与适应机制类似。此外，该实验中仅在前一试次脑电稳态诱发电位反应较低时，才存在显著的时间-内容关联。

上述结果初步证实了并行表征多项时间-内容配对预测的可行性，但未来仍需开展更多研究以深入探究该交互作用的具体机制。