Walker Gary A, Ohzawa Izumi, Freeman Ralph D
Group in Vision Science, School of Optometry, University of California, Berkeley, Berkeley, CA 94720-2020, USA.
J Neurosci. 2002 Jul 1;22(13):5659-68. doi: 10.1523/JNEUROSCI.22-13-05659.2002.
By definition, the region outside the classical receptive field (CRF) of a neuron in the visual cortex does not directly activate the cell. However, the response of a neuron can be influenced by stimulation of the surrounding area. In previous work, we showed that this influence is mainly suppressive and that it is generally limited to a local region outside the CRF. In the experiments reported here, we investigate the mechanisms of the suppressive effect. Our approach is to find the position of a grating patch that is most effective in suppressing the response of a cell. We then use a masking stimulus at different contrasts over the grating patch in an attempt to disinhibit the response. We find that suppressive effects may be partially or completely reversed by use of the masking stimulus. This disinhibition suggests that effects from outside the CRF may be local. Although they do not necessarily underlie the perceptual analysis of a figure-ground visual scene, they may provide a substrate for this process.
根据定义，视觉皮层中神经元经典感受野（CRF）之外的区域不会直接激活该细胞。然而，神经元的反应会受到周围区域刺激的影响。在之前的工作中，我们表明这种影响主要是抑制性的，并且通常局限于CRF之外的局部区域。在此报道的实验中，我们研究了这种抑制作用的机制。我们的方法是找到对抑制细胞反应最有效的光栅斑块的位置。然后我们在光栅斑块上使用不同对比度的掩蔽刺激，试图解除抑制反应。我们发现，使用掩蔽刺激可能会部分或完全逆转抑制作用。这种去抑制表明CRF之外的影响可能是局部的。虽然它们不一定是图形-背景视觉场景感知分析的基础，但它们可能为这一过程提供了一个基础。
