Li Yaju, Noguchi Yasuki
Department of Psychology, Graduate School of Humanities, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe 657-8501, Japan.
Cereb Cortex Commun. 2022 Apr 9;3(2):tgac015. doi: 10.1093/texcom/tgac015. eCollection 2022.
Previous studies have shown that a rate of temporal decline in visual working memory (vWM) highly depends on a number of memory items. When people retain the information of many (≥ 4) stimuli simultaneously, their memory representations are fragile and rapidly degrade within 2-3 s after an offset (called the "competition" among memory items). When a memory load is low (1 or 2 items), in contrast, the fidelity of vWM is preserved for a longer time because focused attention to the small number of items prevents the temporal degradation. In the present study, we explored neural correlates of this load-dependent decline of vWM in the human brain. Using electroencephalography and a classical change-detection task, we recorded neural measures of vWM that have been reported previously, such as the contralateral delay activity (CDA) and a suppression of alpha power (8-12 Hz). Results indicated that the load-dependent decline of vWM was more clearly reflected in the change in power and speed of alpha/beta rhythm than CDA, suggesting a close relationship of those signals to an attention-based preservation of WM fidelity.
先前的研究表明，视觉工作记忆（vWM）随时间衰退的速率高度依赖于记忆项目的数量。当人们同时保留许多（≥4）刺激的信息时，他们的记忆表征很脆弱，并且在刺激消失后2 - 3秒内迅速衰退（这被称为记忆项目之间的“竞争”）。相比之下，当记忆负荷较低（1或2个项目）时，vWM的保真度能在更长时间内得以保持，因为对少量项目的集中注意力可防止随时间衰退。在本研究中，我们探究了人类大脑中这种依赖负荷的vWM衰退的神经关联。使用脑电图和经典的变化检测任务，我们记录了先前已报道的vWM的神经指标，如对侧延迟活动（CDA）和α波功率（8 - 12Hz）的抑制。结果表明，与CDA相比，依赖负荷的vWM衰退在α/β节律的功率和速度变化中体现得更为明显，这表明这些信号与基于注意力的WM保真度保持密切相关。
