Ongoing Activity Fluctuations in hMT plus Bias the Perception of Coherent Visual Motion
Ongoing Activity Fluctuations in hMT plus Bias the Perception of Coherent Visual Motion
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DOI：
10.1523/jneurosci.4398-08.2008
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发表时间：
2008-12-31
影响因子：
5.3
通讯作者：
Kleinschmidt, Andreas
中科院分区：
文献类型：
--
作者：
Hesselmann, Guido;Kell, Christian A.;Kleinschmidt, Andreas
我们最近已经证明，基线期间正在进行的活动的内在波动对报告的模糊视觉刺激的知觉决定有影响(Hesselmann等人，2008年)。为了测试这一结果是否从视觉对象领域推广到其他知觉和神经系统，目前的研究调查了运动敏感脑区持续信号波动对连贯视觉运动感知的影响。我们使用动态随机点显示分别为每个受试者确定运动一致性阈值。在功能磁共振成像(FMRI)中，出现短暂的阈值下、阈值上和阈值周围的相干运动，它们之间存在较长且可变的相互刺激间隔。在每一次试验中，受试者报告他们是否感觉到了“连贯”或“随机”的运动，并分别分析了fMRI信号时间进程作为刺激和感知类型的函数。在右侧运动敏感的枕颞叶皮质(HMT+)，对周围刺激的连贯知觉比随机知觉产生更大的刺激诱发反应。在这些连贯试验中，该区域的刺激前基线活动也显著高于随机试验。然而，与我们之前的研究一样，持续活动和诱发活动之间的关系不是相加的，而是与知觉结果相互作用的。因此，我们的数据表明，基线活动的内源性波动对随后的知觉决策具有一般性影响。尽管功能神经成像中使用的主流分析技术没有捕捉到基线对诱发反应的这种非加性效应，但它符合理论框架中的假设，例如预测性编码。
We have recently shown that intrinsic fluctuations of ongoing activity during baseline have an impact on perceptual decisions reported for an ambiguous visual stimulus (Hesselmann et al., 2008). To test whether this result generalizes from the visual object domain to other perceptual and neural systems, the current study investigated the effect of ongoing signal fluctuations in motion-sensitive brain regions on the perception of coherent visual motion. We determined motion coherence thresholds individually for each subject using a dynamic random dot display. During functional magnetic resonance imaging ( fMRI), brief events of subliminal, supraliminal, and periliminal coherent motion were presented with long and variable interstimulus intervals between them. On each trial, subjects reported whether they had perceived "coherent" or "random" motion, and fMRI signal time courses were analyzed separately as a function of stimulus and percept type. In the right motion-sensitive occipito-temporal cortex (hMT+), coherent percepts of periliminal stimuli yielded a larger stimulus-evoked response than random percepts. Prestimulus baseline activity in this region was also significantly higher in these coherent trials than in random trials. As in our previous study, however, the relation between ongoing and evoked activity was not additive but interacted with perceptual outcome. Our data thus suggest that endogenous fluctuations in baseline activity have a generic effect on subsequent perceptual decisions. Although mainstream analytical techniques used in functional neuroimaging do not capture this nonadditive effect of baseline on evoked response, it is in accord with postulates from theoretical frameworks as, for instance, predictive coding.