Cross-orientation suppression in human visual cortex
Cross-orientation suppression in human visual cortex
复制标题
DOI：
10.1152/jn.00540.2011
复制
发表时间：
2011-11-01
影响因子：
2.5
通讯作者：
Heeger, David J.
中科院分区：
文献类型：
--
作者：
Brouwer, Gijs Joost;Heeger, David J.
Brouwer GJ Heeger DJ.人类视觉皮层中的交叉定向抑制。J Neurophysiol 106：2108-2119，2011.首次发表于2011年7月20日; doi：10.1152/jn.00540.2011。在人类初级视皮层（V1）中测量交叉取向抑制以测试归一化模型。受试者观察垂直目标光栅（不同对比度），有或没有叠加的水平掩模光栅（固定对比度）。我们使用功能性磁共振成像（fMRI）来测量具有不同方向调谐的几个假设通道（对应于神经元亚群）中的每一个的活动，并将这些方向选择性响应与归一化模型拟合。对于最大调谐到目标方向的V1通道，响应随目标对比度增加而增加，但在添加水平掩模时受到抑制，这明显表现为该通道响应的对比度增益的偏移。对于最大限度地调整到掩模方向的通道，当掩模不存在时，所有目标对比度都会引起恒定的基线响应;当掩模存在时，响应随着目标对比度的增加而降低。归一化模型提供了一个很好的适合的对比度响应函数与掩模和没有。在对照实验中，目标和掩模呈现在时间上交错，并且我们没有发现对比度增益的偏移，即，没有证据表明是被压制的我们的结论是，归一化模型可以解释在人类视觉皮层的交叉方向抑制。这里采用的方法可以广泛地应用于推断，同时，在人类大脑中的几个亚群的神经元，跨越特定的刺激或特征空间的反应，并表征它们的相互作用。此外，它使我们能够研究刺激如何由整个神经群体的推断活动来表示。
Brouwer GJ, Heeger DJ. Cross-orientation suppression in human visual cortex. J Neurophysiol 106: 2108-2119, 2011. First published July 20, 2011; doi:10.1152/jn.00540.2011.-Cross-orientation suppression was measured in human primary visual cortex (V1) to test the normalization model. Subjects viewed vertical target gratings (of varying contrasts) with or without a superimposed horizontal mask grating (fixed contrast). We used functional magnetic resonance imaging (fMRI) to measure the activity in each of several hypothetical channels (corresponding to subpopulations of neurons) with different orientation tunings and fit these orientation-selective responses with the normalization model. For the V1 channel maximally tuned to the target orientation, responses increased with target contrast but were suppressed when the horizontal mask was added, evident as a shift in the contrast gain of this channel's responses. For the channel maximally tuned to the mask orientation, a constant baseline response was evoked for all target contrasts when the mask was absent; responses decreased with increasing target contrast when the mask was present. The normalization model provided a good fit to the contrast-response functions with and without the mask. In a control experiment, the target and mask presentations were temporally interleaved, and we found no shift in contrast gain, i.e., no evidence for suppression. We conclude that the normalization model can explain cross-orientation suppression in human visual cortex. The approach adopted here can be applied broadly to infer, simultaneously, the responses of several subpopulations of neurons in the human brain that span particular stimulus or feature spaces, and characterize their interactions. In addition, it allows us to investigate how stimuli are represented by the inferred activity of entire neural populations.