The Behavioral and Cognitive Neuroscience Program, CUNY Graduate Center, New York, New York, USA.
Department of Psychology, The City College of New York, New York, New York, USA.
Brain Connect. 2022 Dec;12(10):892-904. doi: 10.1089/brain.2021.0171. Epub 2022 Jun 1.
One manipulation used to study the neural basis of working memory (WM) is to vary the information load at encoding, then measure activity and connectivity during maintenance in the delay period. A hallmark finding is increased delay activity and connectivity between frontoparietal brain regions with increased load. Most WM studies, however, employ simple stimuli during encoding and unfilled intervals during the delay. In this study, we asked how delay period activity and connectivity change during low and high load maintenance of complex stimuli. Twenty-two participants completed a modified Sternberg WM task with two or five naturalistic scenes as stimuli during scalp electroencephalography (EEG). On each trial, the delay was filled with phase-scrambled scenes to provide a visual perceptual control with similar color and spatial frequency as presented during encoding. Functional connectivity during the delay was assessed by the phase-locking value (PLV). Results showed reduced theta/alpha delay activity amplitude during high compared with low WM load across frontal, central, and parietal sources. A network with higher connectivity during low load consisted of increased PLV between (1) left frontal and right posterior temporal sources in the theta/alpha bands, (2) right anterior temporal and left central sources in the alpha and lower beta bands, and (3) left anterior temporal and posterior temporal sources in the theta, alpha, and lower beta bands. The findings suggest a role for interhemispheric connectivity during WM maintenance of complex stimuli with load modulation when limited attentional resources are essential for filtering. Impact statement The patterns of brain connectivity subserving working memory (WM) have largely been investigated to date using simple stimuli, including letters, digits, and shapes and during unfilled WM delay intervals. Fewer studies describe functional connectivity changes during the maintenance of more naturalistic stimuli in the presence of distractors. In the present study, we employed a scene-based WM task during electroencephalography in healthy humans and found that during low-load WM maintenance with distractors increased interhemispheric connectivity in frontotemporal networks. These findings suggest a role for increased interhemispheric connectivity during maintenance of complex stimuli when attentional resources are essential for filtering.
一种用于研究工作记忆 (WM) 神经基础的操作方法是在编码时改变信息负载，然后在延迟期间测量维持过程中的活动和连接。一个显著的发现是，随着负载的增加，额顶叶脑区之间的延迟活动和连接增加。然而，大多数 WM 研究在编码期间使用简单的刺激，在延迟期间使用未填充的间隔。在这项研究中，我们想知道在低负荷和高负荷维持复杂刺激时，延迟期间的活动和连接如何变化。 22 名参与者在头皮脑电图 (EEG) 期间完成了一项修改后的 Sternberg WM 任务，任务中使用两个或五个自然场景作为刺激。在每次试验中，延迟期间充满了相位混淆的场景，以提供与编码期间呈现的相似颜色和空间频率的视觉感知控制。通过相位锁定值 (PLV) 评估延迟期间的功能连接。 结果表明，与低 WM 负载相比，高 WM 负载时，额顶叶来源的θ/α 延迟活动幅度降低。在低负载时，一个连接性更高的网络包括在θ/α 频段中（1）左额和右后颞源之间，（2）α 和较低β 频段中右前颞和左中央源之间，以及（3）θ、α 和较低β 频段中左前颞和后颞源之间的 PLV 增加。 研究结果表明，在存在干扰时，复杂刺激的 WM 维持需要注意力资源过滤，此时半球间连接可能在负载调节中起作用。 研究意义 迄今为止，工作记忆 (WM) 的脑连接模式主要使用简单的刺激（包括字母、数字和形状）进行研究，并且在 WM 延迟间隔期间没有填充。在存在干扰的情况下，使用更自然的刺激维持 WM 时，功能连接变化的研究较少。在本研究中，我们在健康人类中使用基于场景的 WM 任务进行脑电图，并发现，在存在干扰时，低负载 WM 维持期间，额颞网络中的半球间连接增加。这些发现表明，在注意力资源对过滤至关重要的情况下，复杂刺激维持期间增加半球间连接可能起作用。
