Small Saccades and Image Complexity during Free Viewing of Natural Images in Schizophrenia.
Small Saccades and Image Complexity during Free Viewing of Natural Images in Schizophrenia.
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DOI：
10.3389/fpsyt.2013.00037
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发表时间：
2013
影响因子：
4.7
通讯作者：
Maldonado PE
中科院分区：
文献类型：
--
作者：
Egaña JI;Devia C;Mayol R;Parrini J;Orellana G;Ruiz A;Maldonado PE
在精神分裂症中，患者在执行简单的视觉任务（如反跳跃或平滑追踪）时表现出功能障碍。在更多的生态场景中，例如自由观看自然图像，患者似乎进行更少和更长的视觉注视，并显示更短的扫描路径。目前尚不清楚这些测量结果是否反映了他们进行基本眼球运动（如扫视和注视）的熟练程度的变化，或者与高级机制（如探索或注意力）有关。我们利用自由探索的自然图像的不同复杂性作为一个模型的生态背景下，正常运作的视觉控制机制可以准确地测量。我们使用标准的SR-Research眼动仪算法（SR）将视觉探索量化为欧几里得距离、扫描路径、扫视和视觉注视。然后，我们将此结果与包括微扫视（EM）的计算进行了比较。我们评估了8名精神分裂症患者和相应的健康对照（HC）。接下来，我们测试了扫视和注视次数的减少，以及先前在精神分裂症患者中报道的持续时间的增加，是否是由于未检测到的微扫视的发生率增加。我们发现，当使用标准SR算法时，患者显示较短的扫描路径以及更少和更短的扫视和注视。当我们采用EM算法时，患者和HC之间这些参数的差异不再显著。另一方面，我们发现图像复杂性在探索行为中起着重要的作用，这一因素解释了精神分裂症患者眼动行为的大部分差异。这些结果有助于阐明精神分裂症中受影响的视觉运动控制机制，并有助于找到诊断和治疗这种疾病的适当标志物。
In schizophrenia, patients display dysfunctions during the execution of simple visual tasks such as antisaccade or smooth pursuit. In more ecological scenarios, such as free viewing of natural images, patients appear to make fewer and longer visual fixations and display shorter scanpaths. It is not clear whether these measurements reflect alterations in their proficiency to perform basic eye movements, such as saccades and fixations, or are related to high-level mechanisms, such as exploration or attention. We utilized free exploration of natural images of different complexities as a model of an ecological context where normally operative mechanisms of visual control can be accurately measured. We quantified visual exploration as Euclidean distance, scanpaths, saccades, and visual fixation, using the standard SR-Research eye tracker algorithm (SR). We then compared this result with a computation that includes microsaccades (EM). We evaluated eight schizophrenia patients and corresponding healthy controls (HC). Next, we tested whether the decrement in the number of saccades and fixations, as well as their increment in duration reported previously in schizophrenia patients, resulted from the increasing occurrence of undetected microsaccades. We found that when utilizing the standard SR algorithm, patients displayed shorter scanpaths as well as fewer and shorter saccades and fixations. When we employed the EM algorithm, the differences in these parameters between patients and HC were no longer significant. On the other hand, we found that image complexity plays an important role in exploratory behaviors, demonstrating that this factor explains most of differences between eye-movement behaviors in schizophrenia patients. These results help elucidate the mechanisms of visual motor control that are affected in schizophrenia and contribute to the finding of adequate markers for diagnosis and treatment for this condition.