Erhart Mira, Czoschke Stefan, Fischer Cora, Bledowski Christoph, Kaiser Jochen
Institute of Medical Psychology, Medical Faculty, Goethe University Frankfurt am Main, Frankfurt am Main, Germany.
International Max Planck Research School - Translational Psychiatry (IMPRS-TP), Max Planck Institute of Psychiatry, Munich, Germany.
Front Neurosci. 2021 Feb 19;15:637877. doi: 10.3389/fnins.2021.637877. eCollection 2021.
Research on visual working memory has shown that individual stimulus features are processed in both specialized sensory regions and higher cortical areas. Much less evidence exists for auditory working memory. Here, a main distinction has been proposed between the processing of spatial and non-spatial sound features. Our aim was to examine feature-specific activation patterns in auditory working memory.
We collected fMRI data while 28 healthy adults performed an auditory delayed match-to-sample task. Stimuli were abstract sounds characterized by both spatial and non-spatial information, i.e., interaural time delay and central frequency, respectively. In separate recording blocks, subjects had to memorize either the spatial or non-spatial feature, which had to be compared with a probe sound presented after a short delay. We performed both univariate and multivariate comparisons between spatial and non-spatial task blocks.
Processing of spatial sound features elicited a higher activity in a small cluster in the superior parietal lobe than did sound pattern processing, whereas there was no significant activation difference for the opposite contrast. The multivariate analysis was applied using a whole-brain searchlight approach to identify feature-selective processing. The task-relevant auditory feature could be decoded from multiple brain regions including the auditory cortex, posterior temporal cortex, middle occipital gyrus, and extended parietal and frontal regions.
In summary, the lack of large univariate activation differences between spatial and non-spatial processing could be attributable to the identical stimulation in both tasks. In contrast, the whole-brain multivariate analysis identified feature-specific activation patterns in widespread cortical regions. This suggests that areas beyond the auditory dorsal and ventral streams contribute to working memory processing of auditory stimulus features.
视觉工作记忆的研究表明，个体刺激特征在专门的感觉区域和更高层次的皮质区域均得到处理。而关于听觉工作记忆的证据则少得多。在此，有人提出空间和非空间声音特征的处理之间存在主要区别。我们的目的是研究听觉工作记忆中特定特征的激活模式。
我们收集了28名健康成年人在执行听觉延迟样本匹配任务时的功能磁共振成像（fMRI）数据。刺激是分别以空间和非空间信息为特征的抽象声音，即双耳时间延迟和中心频率。在不同的记录块中，受试者必须记住空间或非空间特征，该特征必须与短延迟后呈现的探测声音进行比较。我们对空间和非空间任务块进行了单变量和多变量比较。
与声音模式处理相比，空间声音特征的处理在顶上小叶的一个小簇中引发了更高的活动，而相反对比则没有显著的激活差异。多变量分析采用全脑搜索光方法来识别特征选择性处理。与任务相关的听觉特征可以从包括听觉皮层、颞叶后皮质、枕中回以及顶叶和额叶扩展区域在内的多个脑区中解码出来。
总之，空间和非空间处理之间缺乏大的单变量激活差异可能归因于两项任务中的相同刺激。相比之下，全脑多变量分析在广泛的皮质区域中识别出了特定特征的激活模式。这表明，除了听觉背侧和腹侧流之外的区域也有助于听觉刺激特征的工作记忆处理。
