Laboratorium voor Neuro-en Psychofysiologie, Departement of Neurosciences, Campus Gasthuisberg, B 3000 Leuven, Belgium.
Department of Medical Physiology, University of Szeged, Dóm square 10, 6720 Szeged, Hungary.
Cereb Cortex. 2018 Jan 1;28(1):250-266. doi: 10.1093/cercor/bhw374.
Humans are sensitive to statistical regularities in their visual environment, but the nature of the underlying neural statistical learning signals still remains to be clarified. As in human behavioral and neuroimaging studies of statistical learning, we exposed rhesus monkeys to a continuous stream of images, presented without interstimulus interval or reward association. The stimulus set consisted of 3 groups of 5 images each (quintets). The stimulus order within each quintet was fixed, but the quintets were presented repeatedly in a random order without interruption. Thus, only transitional probabilities defined quintets of images. Postexposure recordings in inferior temporal (IT) cortex showed an enhanced response to stimuli that violated the exposed sequence. This enhancement was found only for stimuli that were not predicted by the just preceding stimulus, reflecting a temporally adjacent stimulus relationship, and was sensitive to stimulus order. By comparing IT responses with sequences with and without statistical regularities, we observed a short latency, transient response suppression for stimuli of the sequence with regularities, in addition to a later sustained response enhancement to stimuli that violated the sequence with regularities. These findings constrain models of mechanisms underlying neural responses in predictable temporal sequences, such as predictive coding.
人类对视觉环境中的统计规律很敏感，但潜在的神经统计学习信号的性质仍有待阐明。在对恒河猴进行的统计学习的人类行为和神经影像学研究中，我们向其展示了一连串没有刺激间隔或奖励关联的图像。刺激集由每组 5 张图片组成（五重奏）。每组内的刺激顺序是固定的，但五重奏会以随机顺序重复播放，中间没有中断。因此，只有过渡概率定义了图像的五重奏。在颞下回（IT）皮层的暴露后记录显示，对违反暴露序列的刺激的反应增强。这种增强仅适用于不受前一个刺激预测的刺激，反映了时间上相邻的刺激关系，并且对刺激顺序敏感。通过比较具有和不具有统计规律的 IT 响应，我们观察到对于具有规律性的序列中的刺激，除了对违反具有规律性的序列的刺激的后期持续反应增强之外，还存在潜伏期短、瞬态反应抑制。这些发现限制了预测性编码等可预测时间序列中神经反应机制的模型。
