Medical Research Council, Cognition and Brain Sciences Unit, Cambridge, UK. kristjan.kalm@ mrc-cbu.cam.ac.uk
J Cogn Neurosci. 2013 Jul;25(7):1111-21. doi: 10.1162/jocn_a_00378. Epub 2013 Feb 28.
Much of what we need to remember consists of sequences of stimuli, experiences, or events. Repeated presentation of a specific sequence establishes a more stable long-term memory, as shown by increased recall accuracy over successive trials of an STM task. Here we used fMRI to study the neural mechanisms that underlie sequence learning in the auditory-verbal domain. Specifically, we track the emergence of neural representations of sequences over the course of learning using multivariate pattern analysis. For this purpose, we use a serial recall task, in which participants have to recall overlapping sequences of letter names, with some of those sequences being repeated and hence learned over the course of the experiment. We show that voxels in the hippocampus come to encode the identity of specific repeated sequences although the letter names were common to all sequences in the experiment. These changes could have not been caused by changes in overall level of activity or to fMRI signal-to-noise ratios. Hence, the present results go beyond conventional univariate fMRI methods in showing a critical contribution of medial-temporal lobe memory systems to establishing long-term representations of verbal sequences.
我们需要记住的很多内容都是由刺激、经历或事件序列组成的。通过多次呈现特定序列，可以建立更稳定的长期记忆，这一点在 STM 任务的连续试验中表现为召回准确性的提高。在这里，我们使用 fMRI 研究了听觉-言语领域中序列学习的神经机制。具体来说，我们使用多元模式分析来跟踪学习过程中序列神经表示的出现。为此，我们使用串行回忆任务，其中参与者必须回忆重叠的字母名称序列，其中一些序列在实验过程中被重复并因此被学习。我们表明，尽管实验中的所有序列都有相同的字母名称，但海马体中的体素开始编码特定重复序列的身份。这些变化不可能是由于整体活动水平或 fMRI 信号与噪声比的变化引起的。因此，目前的结果超越了传统的单变量 fMRI 方法，表明内侧颞叶记忆系统对建立言语序列的长期表示具有关键贡献。
