Department of Psychology, Rice University, MS-25, P.O. Box 1892, Houston, TX, USA.
Department of Psychology, University of Notre Dame, Notre Dame, IN, USA.
Cereb Cortex. 2019 Apr 1;29(4):1398-1413. doi: 10.1093/cercor/bhy037.
Buffer versus embedded processes accounts of short-term memory (STM) for phonological information were addressed by testing subjects' perception and memory for speech and non-speech auditory stimuli. Univariate and multivariate (MVPA) approaches were used to assess whether brain regions recruited in recognizing speech were involved in maintaining speech representations over a delay. As expected, a left superior temporal region was found to support speech perception. However, contrary to the embedded processes approach, this region failed to show a load effect, or any sustained activation, during a maintenance delay. Moreover, MVPA decoding during the maintenance stage was unsuccessful in this region by a perception classifier or an encoding classifier. In contrast, the left supramarginal gyrus showed both sustained activation and a load effect. Using MVPA, stimulus decoding was successful during the delay period. In addition, a functional connectivity analysis showed that, as memory load increased, the left temporal lobe involved in perception became more strongly connected with the parietal region involved in maintenance. Taken together, the findings provide greater support for a buffer than embedded processes account of phonological STM.
对语音信息的短期记忆（STM）的缓冲区与嵌入式过程的解释，通过测试对象对语音和非语音听觉刺激的感知和记忆来解决。使用单变量和多变量（MVPA）方法来评估识别语音时所涉及的大脑区域是否参与维持延迟期间的语音表示。正如预期的那样，发现左颞上区域支持语音感知。然而，与嵌入式过程方法相反，在维持延迟期间，该区域没有表现出负载效应或任何持续的激活。此外，在维持阶段，感知分类器或编码分类器都无法在该区域进行 MVPA 解码。相比之下，左缘上回显示出持续的激活和负载效应。使用 MVPA，在延迟期间成功进行了刺激解码。此外，功能连接分析表明，随着记忆负荷的增加，参与感知的左颞叶与参与维持的顶叶区域的连接变得更强。总之，这些发现为语音 STM 的缓冲区解释提供了比嵌入式过程解释更大的支持。
