Department of Psychological Sciences, Rice University, Houston, TX 77005, USA; Department of Psychology, Vanderbilt University, Nashville, TN 37240, USA.
Department of Psychological Sciences, Rice University, Houston, TX 77005, USA.
Cortex. 2021 May;138:72-89. doi: 10.1016/j.cortex.2021.01.020. Epub 2021 Feb 12.
Buffer accounts of verbal short-term memory (STM) assume dedicated buffers for maintaining different types of information (e.g., phonological, visual) whereas embedded processes accounts argue against the existence of buffers and claim that STM consists of the activated portion of long-term memory (LTM). We addressed this debate by determining whether STM recruits the same neural substrate as LTM, or whether additional regions are involved in short-term storage. Using fMRI with representational similarity analysis (RSA), we examined the representational correspondence of multi-voxel neural activation patterns with the theoretical predictions for the maintenance of both phonological and semantic codes in STM. We found that during the delay period of a phonological STM task, phonological representations could be decoded in the left supramarginal gyrus (SMG) but not the superior temporal gyrus (STG), a speech processing region, for word stimuli. Whereas the pattern in the SMG was specific to phonology, a different region in the left angular gyrus showed RSA decoding evidence for the retention of either phonological or semantic codes, depending on the task context. Taken together, the results provide clear support for a dedicated buffer account of phonological STM, although evidence for a semantic buffer is equivocal.
语音工作记忆（STM）的缓冲区假设为维持不同类型的信息（例如，语音、视觉）提供专用缓冲区，而嵌入式处理假设则反对缓冲区的存在，并声称 STM 由长期记忆（LTM）的激活部分组成。我们通过确定 STM 是否招募与 LTM 相同的神经基质，或者是否有其他区域参与短期存储，来解决这场争论。我们使用功能磁共振成像（fMRI）和表示相似性分析（RSA），研究了多体素神经激活模式的表示对应关系，以及理论预测在 STM 中维持语音和语义代码的对应关系。我们发现，在语音 STM 任务的延迟期间，对于词刺激，语音表示可以在左顶下小叶（SMG）中解码，但不能在语音处理区域的颞上回（STG）中解码。虽然 SMG 中的模式是特定于语音的，但左角回中的另一个区域显示 RSA 解码证据表明，根据任务上下文，保留语音或语义代码。总的来说，结果为语音 STM 的专用缓冲区假设提供了明确的支持，尽管语义缓冲区的证据存在争议。
