Center for Neuroscience, University of California, Davis, Davis, California; Department of Psychology, University of California, Davis, Davis, California.
Department of Psychology, University of California, Berkeley, Berkeley, California; Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, California.
Biol Psychiatry Cogn Neurosci Neuroimaging. 2021 Dec;6(12):1157-1164. doi: 10.1016/j.bpsc.2021.04.002. Epub 2021 Apr 17.
People with schizophrenia (SZ) exhibit impaired episodic memory when relating objects to each other in time and space. Empirical studies and computational models suggest that low-frequency neural oscillations may be a mechanism by which the brain keeps track of temporal relationships during encoding and retrieval, with modulation of oscillatory power as sequences are learned. It is unclear whether sequence memory deficits in SZ are associated with altered neural oscillations.
Using electroencephalography, this study examined neural oscillations in 51 healthy control subjects and 37 people with SZ during a temporal sequence learning task. Multiple 5-object picture sequences were presented across 4 study-test blocks in either fixed or random order. Participants answered semantic questions for each object (e.g., living/nonliving), and sequence memory was operationalized as faster responses for fixed versus random sequences. Differences in oscillatory power between fixed versus random sequences provided a neural index of temporal sequence memory.
Although both groups showed reaction time differences in late blocks (blocks 3 and 4), this evidence of sequence memory was reduced in people with SZ relative to healthy control subjects. Decreases in globally distributed prestimulus alpha (8-12 Hz) and beta 1 (13-20 Hz) power for fixed versus random sequences in late blocks were also attenuated in people with SZ relative to healthy control subjects. Moreover, changes in oscillatory power predicted individual reaction time differences and fully mediated the relationship between group and sequence memory.
Disrupted modulation of alpha and beta 1 electroencephalography oscillations is a candidate mechanism of temporal sequence memory deficits in people with SZ.
精神分裂症（SZ）患者在将物体在时间和空间上联系起来时表现出情节记忆受损。实证研究和计算模型表明，低频神经振荡可能是大脑在编码和检索过程中跟踪时间关系的一种机制，随着序列的学习，振荡功率的调制。目前尚不清楚 SZ 中的序列记忆缺陷是否与改变的神经振荡有关。
本研究使用脑电图检查了 51 名健康对照者和 37 名 SZ 患者在时间序列学习任务中的神经振荡。在固定或随机顺序下，跨 4 个学习-测试块呈现多个 5 个物体图片序列。参与者为每个物体回答语义问题（例如，有生命/无生命），并将固定与随机序列的反应时间作为序列记忆的操作化。固定与随机序列之间的振荡功率差异提供了时间序列记忆的神经指标。
尽管两组在后期块（第 3 块和第 4 块）都表现出反应时间差异，但与健康对照组相比，SZ 患者的这种序列记忆减少了。在后期块中，与随机序列相比，固定序列的全局分布的静息期 alpha（8-12 Hz）和 beta1（13-20 Hz）功率下降也在 SZ 患者中减弱。此外，振荡功率的变化预测了个体反应时间差异，并完全介导了组间和序列记忆之间的关系。
alpha 和 beta1 脑电图振荡的调制中断是 SZ 患者时间序列记忆缺陷的候选机制。
