Relationship between saccadic eye movements and cortical activity as measured by fMRI: quantitative and qualitative aspects
Relationship between saccadic eye movements and cortical activity as measured by fMRI: quantitative and qualitative aspects
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DOI：
10.1007/s002210100844
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发表时间：
2001-11-01
影响因子：
2
通讯作者：
Mergner, T
中科院分区：
文献类型：
--
作者：
Kimmig, H;Greenlee, MW;Mergner, T
我们利用功能性磁共振成像（fMRI）研究了跳眼活动（反映在跳眼的发生频率和幅度上）与大脑皮层血氧水平依赖性（BOLD）变化之间的定量关系。此外，我们研究了皮层活动的定量变化与扫视任务中扫视活动的质变相关。所有实验都需要同时获取eve运动和fMRI数据。为此，我们使用了一种新的高分辨率边缘跟踪技术来记录核磁共振断层成像中的夏娃运动。在前两个实验系列中，我们改变了扫视刺激（目标跳跃）的频率和幅度。在第三个系列中，我们改变了任务难度，受试者进行亲扫视或反扫视。研究的脑容量包括额叶和补叶，顶叶和纹状皮层，以及顶枕皮层的运动敏感区。所有这些区域都表现出与眼跳相关的BOLD反应。这些区域的反应与扫视频率高度相关，表明随着时间的推移，扫视的重复加工被整合到BOLD反应中。相比之下。眼跳振幅的变化没有可比较的BOLD变化。这一发现表明，在大多数皮层区域，眼跳振幅的编码是拓扑的，而不是活动依赖的。在对比正反扫视的实验中，我们发现在V“反”任务中BOLD的激活比在“正”任务中要高。对比两种任务的眼跳参数发现，眼跳频率和累计幅度具有可比性，而“反”任务的反应时间比“亲”任务的反应时间更长。后一项发现被认为表明在“反”任务中比“亲”任务中需要更多的皮层加工，这可以解释观察到的BOLD激活差异。我们认为，定量分析眼跳参数（尤其是眼跳频率和潜伏期）对于解释fMRI视觉刺激下观察到的BOLD变化很重要。
We investigated the quantitative relationship between saccadic activity (as reflected in frequency of occurrence and amplitude of saccades) and blood oxygenation level dependent (BOLD) changes in the cerebral cortex using functional magnetic resonance imaging (fMRI). Furthermore, we investigated quantitative changes in cortical activity associated with qualitative changes in the saccade task for comparable levels of saccadic activity. All experiments required the simultaneous acquisition of eve movement and fMRI data. For this purpose we used a new high-resolution limbus-tracking technique for recording eve movements in the magnetic resonance tomograph. In the first two experimental series we varied both frequency and amplitude of saccade stimuli (target jumps'). In the third series we varied task difficulty, subjects performed either pro-saccades or anti-saccades. The brain volume investigated comprised the frontal and supplementary eve fields, parietal as well as striate cortex, and the motion sensitive area of the parieto-occipital cortex. All these regions showed saccade-related BOLD responses. The responses in these regions were highly correlated with saccade frequency, indicating that repeated processing of saccades is integrated over time in the BOLD response. In contrast. there was no comparable BOLD change with variation of saccade amplitude. This finding speaks for a topological rather than activity-dependent coding of saccade amplitudes in most cortical regions. In the experiments comparing pros anti-saccades we found higher BOLD activation in the V "anti" task than in the "pro" task. A comparison of saccade parameters revealed that saccade frequency and cumulative amplitude were comparable between the two tasks, whereas reaction times were longer in the "anti" task than the pro task. The latter finding is taken to indicate a more demanding cortical processing in the "anti" task than the "pro" task, which could explain the observed difference in BOLD activation. We hold that a quantitative analysis of saccade parameters (especially saccade frequency and latency) is important for the interpretation of the BOLD changes observed with visual stimuli in fMRI.