Inter-ocular contrast normalization in human visual cortex.
Inter-ocular contrast normalization in human visual cortex.
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DOI：
10.1167/9.3.13
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发表时间：
2009-03-20
影响因子：
1.8
通讯作者：
Heeger DJ
中科院分区：
文献类型：
--
作者：
Moradi F;Heeger DJ
大脑将来自两只眼睛的视觉信息结合起来，形成一个连贯的感知，即使眼睛的输入是不同的。然而，目前尚不清楚来自两只眼睛的输入如何在视觉皮层中组合。我们测量功能磁共振成像反应单目提出的光栅，或对光栅提出单眼或dichoptically与几种组合的对比度。光栅具有相同取向或正交取向（即，格子）。观察员进行了一项艰巨的任务，在固定，以尽量减少自上而下的调制刺激诱发的反应。只有当对比度较低（<10%）时，兼容光栅（相同方向）的双视呈现才比单光栅的单眼呈现诱发更大的活动。一个假设每只眼睛活动线性总和的模型无法解释10%或更高对比度下的双眼反应。然而，具有双眼对比度归一化的模型，使得每只眼睛的活动减少了另一只眼睛的增益，非常适合结果。正交光栅的dichoptic介绍诱发更大的活动比单眼介绍一个单一的光栅的所有对比度。然而，引起的活动，由dichoptic格子是等同于引起的单眼格子。引入一个起始的闪烁（在另一只眼睛之前刺激一只眼睛500 ms，这在注意力集中的视觉下导致闪光抑制）对结果没有影响;对双眼和单眼格子的反应再次相等。我们的结论是，当注意力被转移时，V1中的眼间抑制可以通过归一化模型来解释，在该模型中，正交方向之间的相互抑制不依赖于眼睛的起源，也不依赖于发病时间，并且交叉方向抑制比眼间（相同方向）抑制弱。
The brain combines visual information from the two eyes and forms a coherent percept, even when inputs to the eyes are different. However, it is not clear how inputs from the two eyes are combined in visual cortex. We measured fMRI responses to single gratings presented monocularly, or pairs of gratings presented monocularly or dichoptically with several combinations of contrasts. Gratings had either the same orientation or orthogonal orientations (i.e., plaids). Observers performed a demanding task at fixation to minimize top-down modulation of the stimulus-evoked responses. Dichoptic presentation of compatible gratings (same orientation) evoked greater activity than monocular presentation of a single grating only when contrast was low (<10%). A model that assumes linear summation of activity from each eye failed to explain binocular responses at 10% contrast or higher. However, a model with binocular contrast normalization, such that activity from each eye reduced the gain for the other eye, fitted the results very well. Dichoptic presentation of orthogonal gratings evoked greater activity than monocular presentation of a single grating for all contrasts. However, activity evoked by dichoptic plaids was equal to that evoked by monocular plaids. Introducing an onset asynchrony (stimulating one eye 500 ms before the other, which under attentive vision results in flash suppression) had no impact on the results; the responses to dichoptic and monocular plaids were again equal. We conclude that when attention is diverted, inter-ocular suppression in V1 can be explained by a normalization model in which the mutual suppression between orthogonal orientations does not depend on the eye of origin, nor on the onset times, and cross-orientation suppression is weaker than inter-ocular (same orientation) suppression.
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影响因子：
1.8
作者：
Boynton, GM;Demb, JB;Heeger, DJ
通讯作者：
Heeger, DJ
影响因子：
1.8
作者：
BAUMAN, LA;BONDS, AB
通讯作者：
BONDS, AB
影响因子：
2
作者：
B端chert, M;Greenlee, MW;Hennig, J
通讯作者：
Hennig, J
影响因子：
16.2
作者：
Alais, David;Parker, Amanda
通讯作者：
Parker, Amanda
影响因子：
16.2
作者：
Baccus, SA;Meister, M
通讯作者：
Meister, M