Uncertainty and invariance in the human visual cortex.
Uncertainty and invariance in the human visual cortex.
复制标题
人类视觉皮层的不确定性和不变性。
DOI：
10.1152/jn.01367.2005
复制
发表时间：
2006
影响因子：
2.5
通讯作者：
Kourtzi,Zoe
中科院分区：
文献类型：
--
作者：
Tjan,BoscoS;Lestou,Vaia;Kourtzi,Zoe
输入噪声干扰系统行为的方式取决于系统的内部处理结构。在视觉心理物理学中，使用外部噪声方法（即，将噪声添加到视觉刺激）作为系统识别的工具。在这里，我们表明，外部噪声影响处理的视觉场景在不同的皮层区域沿着人类腹侧视觉通路，从retinotopic区域更高的枕颞区涉及视觉形状处理。我们发现，当刺激的对比度保持不变时，离视网膜输入越远的皮层区域的活动越多，用功能磁共振成像（fMRI）测量，取决于视觉刺激的信噪比（SNR）。当分别分析正确和不正确反应的试验时，观察到类似的结果模式。我们通过将信号检测理论扩展到功能磁共振成像数据分析来解释这些发现。这种方法揭示了顺序排序的决策阶段在皮层利用功能磁共振成像响应和刺激信噪比之间的关系。特别是，我们的研究结果提供了新的证据表明，枕颞区腹侧视觉通路形成了一个级联的决策阶段，信号的不确定性和功能的不变性程度增加。
The way in which input noise perturbs the behavior of a system depends on the internal processing structure of the system. In visual psychophysics, there is a long tradition of using external noise methods (i.e., adding noise to visual stimuli) as tools for system identification. Here, we demonstrate that external noise affects processing of visual scenes at different cortical areas along the human ventral visual pathway, from retinotopic regions to higher occipitotemporal areas implicated in visual shape processing. We found that when the contrast of the stimulus was held constant, the further away from the retinal input a cortical area was the more its activity, as measured with functional magnetic resonance imaging (fMRI), depended on the signal-to-noise ratio (SNR) of the visual stimulus. A similar pattern of results was observed when trials with correct and incorrect responses were analyzed separately. We interpret these findings by extending signal detection theory to fMRI data analysis. This approach reveals the sequential ordering of decision stages in the cortex by exploiting the relation between fMRI response and stimulus SNR. In particular, our findings provide novel evidence that occipitotemporal areas in the ventral visual pathway form a cascade of decision stages with increasing degree of signal uncertainty and feature invariance.