Representation, Storage, and Decay in Auditory-Verbal Working Memory

这项拟议的研究的首要目标是显著提高我们对言语工作记忆背后的神经机制的理解。几十年来对言语工作记忆认知心理的研究表明，人们记住言语信息的主要方式是通过潜声排练，或内部言语。换句话说，为了让语言信息在意识中高高在上，我们利用自己的能力与自己进行内部对话。在Baddeley和他的同事的经典言语工作记忆模型中，语音环路，内部语言被分解为两个交流成分：运动/发音过程和语音/听觉成分。在过去的20年里，认知神经科学试图了解这两种成分是如何“映射”到大脑上的。然而，我们对言语工作记忆的机制基础仍然知之甚少。因此，虽然我们知道，在语言信息的在线维护过程中，运动/听觉皮质区域都是“活跃的”，但我们对这些区域进行的计算很少。*在这项提议中，我们使用了一系列功能磁共振成像(FMRI)研究，以阐明语言记忆是在大脑的听觉皮质编码的。随着多体素模式分析(MVPA)技术的出现，现在可以捕捉和可靠地识别编码特定刺激或认知状态的神经激活的分布模式。在这里，我们利用功能磁共振成像技术的这一非凡发展，对听觉记忆提取和内部语音过程中表现出来的听觉皮质活动模式进行“解码”。首先，我们将检验这一假设，即由外部和内部语言引起的活动模式在听觉皮质中具有共同的代表性基础。其次，我们将测试一个关于内在语言的重要描述，该描述表明，它是由于运动到感觉的放电而出现的，而运动到感觉的放电是内部监控电路的一部分，对语音产生中的错误纠正至关重要。最后，我们将研究感知言语的“表面特征”，如性别和口音，是如何被结合到工作记忆中被激活的听觉记忆痕迹中的。*虽然这项提议的重点是听觉-言语通道，但其含义超出了这个“模型子系统”，因为我们从当前的一系列实验中学到的将与其他记忆领域相关和适用。此外，这项工作的一个关键目标是继续追求一套统一的原则，这些原则是不同类型记忆的存储、表征和激活的基础，包括言语记忆、视觉空间记忆、短期记忆和长期记忆、情景记忆和语义记忆。因此，这项工作是一个更大的跨越职业生涯的计划的一部分，其长期目标是设计出对人类记忆更连贯、更少分割的理解。

The overarching goal of the proposed research is to significantly advance our understanding of the neural mechanisms underlying verbal working memory. Decades of research on the cognitive psychology of verbal working memory have shown that the primary way in which people keep verbal information in mind is through subvocal rehearsal, or inner speech. In other words, to keep verbal information aloft in consciousness we make use of our capacity to carry on an internal conversation with ourselves. In Baddeley and colleagues' classic model of verbal working memory, the phonological loop, inner speech is decomposed into two communicating components: a motor/articulatory process and a phonological/auditory component. In the last 20 years, cognitive neuroscience has tried to understand how these two components "map" on to the brain. However, we still have a poor understanding of the mechanistic basis of verbal working memory. Thus, while we know that during the online maintenance of verbal information both motor/ and auditory cortical areas are "active", we have a poor of the computations carried out by these regions.***In this proposal we use a series of functional magnetic resonance imaging (fMRI) studies to elucidate memories for speech are coded in the brain's auditory cortex. With the advent of multivoxel pattern analysis (MVPA) techniques, it is now possible to capture and reliably identify distributed patterns of neural activation that code for particular stimuli or cognitive states. Here we take advantage of this extraordinary development in fMRI technology to "decode" the patterns of activity in auditory cortex that are manifested during auditory memory retrieval and inner speech. First, we will test the hypothesis that patterns of activity evoked by external and inner speech share a representational basis in auditory cortex. Second, we will test a prominent account of inner speech that suggests that it emerges as a result of motor-to-sensory discharges that are part of an internal monitoring circuit important for error correction in speech production. Last, we will investigate how "surface features" of perceived speech, such as gender and accent, are incorporated into the auditory memory traces that are activated during working memory.***Although the focus of this proposal is in the auditory-verbal modality, the implications go beyond this "model subsystem" because the what we learn from the current set of experiments will be relevant and applicable to other memory domains. Furthermore, a key aim of this work is to continue to pursue a set of unifying principles that underlie the storage, representation, and activation of different kinds of memory, including verbal, visuospatial, short- and long-term, episodic and semantic. This work, therefore, is part of a larger career-spanning program with the long-term goal of devising a more coherent and less compartmentalized understanding of human memory.**