Department of Neurology, UZ Brussel, Centre for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels, Belgium.
National MS Center Melsbroek, Melsbroek, Belgium.
PLoS One. 2018 Mar 15;13(3):e0194388. doi: 10.1371/journal.pone.0194388. eCollection 2018.
The paced serial addition test (PSAT) is regularly used to assess cognitive deficits in various neuropsychiatric conditions. Being a complex test, it reflects the status of multiple cognitive domains such as working memory, information processing speed and executive functioning. Two versions of the PSAT exist. One uses auditory stimuli through spoken numbers and is known as the PASAT, while the other one presents patients with visual stimuli and is called PVSAT. The PASAT is considered more frustrating by patients, and hence the visual version is usually preferred. Research has suggested that an interference might exist between patients' verbal answers and the auditory presentation of stimuli. We therefore removed the verbal response in this study, and aimed to investigate differences in functional brain activity through functional magnetic resonance imaging.
Fifteen healthy controls performed the two test versions inside an MRI scanner-switching between stimulus modality (auditory vs. visual) as well as inter-stimulus frequency (3s vs. 2s). We extracted 11 independent components from the data: attentional, visual, auditory, sensorimotor and default mode networks. We then performed statistical analyses of mean network activity within each component, as well as inter-network connectivity of each component pair during the different task types.
Unsurprisingly, we noted an effect of modality on activity in the visual and auditory components. However, we also describe bilateral frontoparietal, anterior cingulate and insular attentional network activity. An effect of frequency was noted only in the sensorimotor network. Effects were found on edges linking visual and auditory regions. Task modality influenced an attentional-sensorimotor connection, while stimulus frequency had an influence on sensorimotor-default mode connections.
Scanner noise during functional MRI may interfere with brain activation-especially during tasks involving auditory pathways. The question whether to use PVSAT or PASAT for an fMRI study is, therefore, an important one. Specific effects of both modalities should be known to study designers. We conclude that both tests should not be considered interchangeable, as significant changes were brought to light during test performance in different modalities.
paced serial addition test（PSAT）常用于评估各种神经精神疾病中的认知缺陷。作为一种复杂的测试，它反映了工作记忆、信息处理速度和执行功能等多个认知领域的状态。PSAT 有两种版本。一种使用通过口语数字呈现的听觉刺激，称为 PASAT，另一种则向患者呈现视觉刺激，称为 PVSAT。PASAT 被患者认为更具挫败感，因此通常更喜欢视觉版本。研究表明，患者的口头回答与听觉刺激呈现之间可能存在干扰。因此，在本研究中我们去除了口头回答，并旨在通过功能磁共振成像研究功能脑活动的差异。
15 名健康对照者在 MRI 扫描仪内进行两种测试版本，在刺激模式（听觉与视觉）以及刺激间频率（3 秒与 2 秒）之间切换。我们从数据中提取了 11 个独立成分：注意力、视觉、听觉、感觉运动和默认模式网络。然后，我们对每个成分内的平均网络活动以及不同任务类型下每个成分对的网络间连接进行了统计分析。
不出所料，我们注意到模式对视觉和听觉成分活动的影响。然而，我们还描述了双侧额顶叶、前扣带和脑岛注意力网络的活动。仅在感觉运动网络中注意到频率的影响。在连接视觉和听觉区域的边缘上发现了效应。任务模式影响注意力-感觉运动连接，而刺激频率对感觉运动-默认模式连接有影响。
功能磁共振成像期间的扫描仪噪声可能会干扰大脑激活-特别是在涉及听觉通路的任务中。因此，对于 fMRI 研究，使用 PVSAT 还是 PASAT 是一个重要问题。研究设计者应该了解这两种模式的特定影响。我们的结论是，这两种测试不应被视为可互换的，因为在不同模式下进行测试时会发现明显的变化。
