Elliott Mark A
School of Psychology, National University of Ireland Galway Galway, Ireland.
Front Psychol. 2014 Sep 12;5:990. doi: 10.3389/fpsyg.2014.00990. eCollection 2014.
Synchronization of spatially distributed neural assemblies at frequencies in the range 30-70 Hz (the "gamma" band) may be instrumental in grouping stimulus features. In agreement with this we have shown that detection reaction times to a grouping target stimulus are expedited when the stimulus is preceded by repeated presentation of a priming stimulus, presented below detection thresholds in a matrix that flickers at particular frequencies in the 27-68 Hz range. This dynamic priming effect can be partly explained as a function of the return phase of the priming stimulus relative to the premask matrix, indicating one of the primary consequences of repeating stimulation is pre-activation of a priming response relative to prime-stimulus presentation. However, this cannot entirely explain the relationship that develops between the timing of stimulus events (in this instance the time of target relative to priming-stimulus presentations) and response. By varying the frequency and phase of priming-stimulus and target presentations we discovered that given a particular relationship between the phase of target presentation relative to the return phase of the prime, target coding is expedited by a prime that achieves its maximum activation at a phase that would precede priming-stimulus presentation by several tens of milliseconds. However, and in addition, the cognition concerned is flexible enough to be able to achieve an identical prime retroactively, that is to say at a phase during or subsequent to priming-stimulus presentation. This occurs because of a different relationship between the phase of target presentation (defined relative to prime frequency) and the frequency of premask-matrix presentation. On this basis, it can be concluded that by virtue of the relationship between its dynamics and the timing of stimulus events, microstructural cognition functions in a temporal context that can shift from past to future states. Consequently and at the lowest level of psychological function, the conventional, one-dimensional model of time flow-from future to past states does not fully explain how cognition can function. In fact depending upon the interaction in phase between different coding frequencies, the same form of cognition can anticipate or retroactively code events. Consequently, and in so far as our cognition at this level provides a content structure for consciousness, our psychological lives may be fundamentally based upon the ability of our cognitive states to travel backwards and forwards across very short intervals of time.
空间分布的神经集合在30 - 70赫兹范围（“伽马”波段）内的频率同步，可能有助于对刺激特征进行分组。与此一致的是，我们已经表明，当在矩阵中以27 - 68赫兹范围内的特定频率闪烁、低于检测阈值呈现的启动刺激重复呈现于分组目标刺激之前时，对分组目标刺激的检测反应时间会加快。这种动态启动效应可以部分解释为启动刺激相对于前置掩蔽矩阵的返回相位的函数，这表明重复刺激的主要后果之一是相对于启动刺激呈现而言对启动反应的预激活。然而，这并不能完全解释刺激事件的时间安排（在这种情况下是目标相对于启动刺激呈现的时间）与反应之间发展起来的关系。通过改变启动刺激和目标呈现的频率和相位，我们发现，给定目标呈现相位相对于启动刺激返回相位的特定关系，当启动刺激在比启动刺激呈现提前几十毫秒的相位达到其最大激活时，目标编码会加快。然而，除此之外，相关认知足够灵活，能够追溯地实现相同的启动，也就是说在启动刺激呈现期间或之后的某个相位。这是由于目标呈现相位（相对于启动频率定义）与前置掩蔽矩阵呈现频率之间的不同关系而发生的。在此基础上，可以得出结论，由于其动态与刺激事件时间安排之间的关系，微观结构认知在一个可以从过去状态转变为未来状态的时间背景中起作用。因此，在心理功能的最低层面上，传统的、从未来到过去状态的一维时间流动模型并不能完全解释认知如何发挥作用。事实上，取决于不同编码频率之间的相位相互作用，相同形式的认知可以预期或追溯地编码事件。因此，就我们在这个层面的认知为意识提供内容结构而言，我们的心理生活可能从根本上基于我们的认知状态在非常短的时间间隔内来回穿梭的能力。
