Harvey Jessica-Lily, Demetriou Lysia, McGonigle John, Wall Matthew B
School of Psychology and Neuroscience, University of St. Andrews, St Andrews, United Kingdom.
Division of Brain Sciences, Imperial College London, London, United Kingdom.
PeerJ. 2018 Sep 11;6:e5540. doi: 10.7717/peerj.5540. eCollection 2018.
Functional magnetic resonance imaging (fMRI) is a popular method for examining pharmacological effects on the brain; however, the BOLD response is dependent on intact neurovascular coupling, and potentially modulated by a number of physiological factors. Pharmacological fMRI is therefore vulnerable to confounding effects of pharmacological probes on general physiology or neurovascular coupling. Controlling for such non-specific effects in pharmacological fMRI studies is therefore an important consideration, and there is an additional need for well-validated fMRI task paradigms that could be used to control for such effects, or for general testing purposes.
We have developed two variants of a standardized control task that are short (5 minutes duration) simple (for both the subject and experimenter), widely applicable, and yield a number of readouts in a spatially diverse set of brain networks. The tasks consist of four functionally discrete three-second trial types (plus additional null trials) and contain visual, auditory, motor and cognitive (eye-movements, and working memory tasks in the two task variants) stimuli. Performance of the tasks was assessed in a group of 15 subjects scanned on two separate occasions, with test-retest reliability explicitly assessed using intra-class correlation coefficients.
Both tasks produced robust patterns of brain activation in the expected brain regions, and region of interest-derived reliability coefficients for the tasks were generally high, with four out of eight task conditions rated as 'excellent' or 'good', and only one out of eight rated as 'poor'. Median values in the voxel-wise reliability measures were also >0.7 for all task conditions, and therefore classed as 'excellent' or 'good'. The spatial concordance between the most highly activated voxels and those with the highest reliability coefficients was greater for the sensory (auditory, visual) conditions than the other (motor, cognitive) conditions.
Either of the two task variants would be suitable for use as a control task in future pharmacological fMRI studies or for any other investigation where a short, reliable, basic task paradigm is required. Stimulus code is available online for re-use by the scientific community.
功能磁共振成像（fMRI）是一种用于研究药物对大脑影响的常用方法；然而，血氧水平依赖（BOLD）反应取决于完整的神经血管耦合，并且可能受到多种生理因素的调节。因此，药物功能磁共振成像容易受到药物探针对一般生理学或神经血管耦合的混杂影响。因此，在药物功能磁共振成像研究中控制此类非特异性效应是一个重要的考虑因素，并且还需要经过充分验证的功能磁共振成像任务范式，可用于控制此类效应或用于一般测试目的。
我们开发了一种标准化控制任务的两个变体，它们简短（持续5分钟）、简单（对受试者和实验者而言）、广泛适用，并在空间上不同的一组脑网络中产生多个读数。这些任务由四种功能上离散的三秒试验类型（加上额外的空试验）组成，并包含视觉、听觉、运动和认知（眼动以及两个任务变体中的工作记忆任务）刺激。在15名受试者的一组中评估了这些任务的表现，这些受试者在两个不同的时间进行扫描，并使用组内相关系数明确评估了重测可靠性。
两个任务在预期的脑区均产生了强大的脑激活模式，并且任务的感兴趣区域衍生的可靠性系数总体较高，八个任务条件中有四个被评为“优秀”或“良好”，只有八个中的一个被评为“差”。所有任务条件的体素级可靠性测量中的中值也>0.7，因此被归类为“优秀”或“良好”。与其他（运动、认知）条件相比，感觉（听觉、视觉）条件下激活程度最高的体素与可靠性系数最高的体素之间的空间一致性更大。
两个任务变体中的任何一个都适合在未来的药物功能磁共振成像研究中用作控制任务，或用于任何其他需要简短、可靠、基本任务范式的研究。刺激代码可在线获取，供科学界重新使用。
