Contrast-dependent, contextual response modulation in primary visual cortex and lateral geniculate nucleus of the cat
Contrast-dependent, contextual response modulation in primary visual cortex and lateral geniculate nucleus of the cat
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DOI：
10.1111/j.1460-9568.2006.04681.x
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发表时间：
2006-03-01
影响因子：
3.4
通讯作者：
Sato, H
中科院分区：
文献类型：
--
作者：
Sadakane, O;Ozeki, H;Sato, H
在初级视皮层（V1）中，神经元对其经典感受野（CRF）内呈现刺激的反应，会受到同时在其周边区域（感受野周边，SRF）呈现的另一刺激的调制。我们研究了猫V1中，SRF刺激相对于刺激对比度的调制效应的本质。在研究的51个V1神经元中，大的SRF刺激（40度×30度）仅诱导对CRF刺激反应的抑制，且随着SRF刺激对比度的增加，抑制作用增强。SRF抑制的对比度敏感性与CRF反应的对比度敏感性不相关。通过独立控制CRF和SRF刺激的对比度，我们研究了SRF效应是否随CRF反应强度而变化。增加CRF刺激的对比度会使SRF刺激的有效对比度范围上移，这表明在高对比度下，需要高对比度的SRF刺激来抑制对CRF刺激的强烈反应。为了评估SRF对V1神经元抑制效应的可能来源，我们还研究了外侧膝状体核中28个神经元的SRF效应的对比度依赖性。我们的结果表明，在皮层下水平获得的SRF效应，对V1中的效应有很大贡献。综上所述，我们得出结论，沿着丘脑皮层投射，SRF调制呈现出一种增益控制机制，该机制根据CRF刺激的对比度来调节SRF的抑制效应。此外，在低刺激对比度下，SRF效应可能具有易化作用，这可能是由于总和野的扩大。
In the primary visual cortex (V1), the responses of neurons to stimuli presented in their classical receptive fields (CRFs) are modulated by another stimulus concurrently presented in their surround (receptive field surround, SRF). We studied the nature of the modulatory effects of SRF stimulation with respect to stimulus contrast in cat V1. In 51 V1 neurons studied, large SRF stimuli (40 degrees x 30 degrees) induced only the suppression of responses to CRF stimulation and the suppressive effects became stronger as the contrast for SRF stimulation increased. The contrast sensitivity of SRF suppression did not correlate with that of CRF responses. By independently controlling contrast of CRF and SRF stimuli, we studied whether SRF effects vary with CRF response magnitude. Increasing contrast for CRF stimulation caused an upward shift of the range of effective contrasts for SRF stimulation, indicating that a high contrast for SRF stimulation is required for suppressing strong responses to CRF stimulation at high contrasts. To assess the possible origin of the suppressive SRF effect on V1 neurons, we also investigated the contrast dependency of SRF effects in 28 neurons from the lateral geniculate nucleus. Our results suggest that SRF effects obtained at the subcortical level strongly contribute to those in V1. Taken together, we conclude that along the thalamocortical projections, SRF modulation exhibits a gain-control mechanism that scales the suppressive SRF effect depending on the contrast for CRF stimulation. In addition, SRF effects can be facilitatory at low stimulus contrasts potentially due to the enlargement of the summation field.