Most fMRI studies investigating smooth pursuit (SP) related brain activity have used simple synthetic stimuli such as a sinusoidally moving dot. However, real-life situations are much more complex and SP does not occur in isolation but within sequences of saccades and fixations. This raises the question whether the same brain networks for SP that have been identified under laboratory conditions are activated when following moving objects in a movie. Here, we used the publicly available studyforrest data set that provides eye movement recordings along with 3 T fMRI recordings from 15 subjects while watching the Hollywood movie "Forrest Gump". All three major eye movement events, namely fixations, saccades, and smooth pursuit, were detected with a state-of-the-art algorithm. In our analysis, smooth pursuit (SP) was the eye movement of interest, while saccades were acting as the steady state of viewing behaviour due to their lower variability. For the fMRI analysis we used an event-related design modelling saccades and SP as regressors initially. Because of the interdependency of SP and content motion, we then added a new low-level content motion regressor to separate brain activations from these two sources. We identified higher BOLD-responses during SP than saccades bilaterally in MT+/V5, in middle cingulate extending to precuneus, and in the right temporoparietal junction. When the motion regressor was added, SP showed higher BOLD-response relative to saccades bilaterally in the cortex lining the superior temporal sulcus, precuneus, and supplementary eye field, presumably due to a confounding effect of background motion. Only parts of V2 showed higher activation during saccades in comparison to SP. Taken together, our approach should be regarded as proof of principle for deciphering brain activity related to SP, which is one of the most prominent eye movements besides saccades, in complex dynamic naturalistic situations.

中文翻译：

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跟随阿甘正传：在免费电影观看期间平滑追求相关的大脑激活

大多数调查平滑追踪 (SP) 相关大脑活动的 fMRI 研究都使用了简单的合成刺激，例如正弦移动点。然而，现实生活中的情况要复杂得多，SP 并不是孤立发生的，而是在一系列的扫视和注视中发生的。这就提出了一个问题，当跟随电影中的移动物体时，是否会激活在实验室条件下识别的相同的 SP 大脑网络。在这里，我们使用了公开可用的 studyforrest 数据集，该数据集在观看好莱坞电影“阿甘正传”时提供眼动记录以及来自 15 名受试者的 3 T fMRI 记录。所有三个主要的眼球运动事件，即注视、扫视和平滑追踪，都是用最先进的算法检测到的。在我们的分析中，平滑追踪 (SP) 是感兴趣的眼球运动，而扫视因其较低的可变性而充当观看行为的稳定状态。对于 fMRI 分析，我们最初使用与事件相关的设计建模扫视和 SP 作为回归量。由于 SP 和内容运动的相互依赖性，我们随后添加了一个新的低级内容运动回归器，以将大脑激活与这两个来源分开。我们在 MT+/V5、延伸至楔前叶的中间扣带回和右侧颞顶交界处发现 SP 期间的 BOLD 反应高于双侧眼跳。当添加运动回归器时，SP 相对于上颞沟、楔前叶和辅助眼场内衬的皮层中的双侧眼跳表现出更高的 BOLD 反应，这可能是由于背景运动的混杂效应。与 SP 相比，只有部分 V2 在扫视期间显示出更高的激活。综上所述，我们的方法应被视为破译与 SP 相关的大脑活动的原理证明，SP 是复杂动态自然环境中除扫视之外最突出的眼球运动之一。