Spatial characteristics of motion-sensitive mechanisms change with age and stimulus spatial frequency
Spatial characteristics of motion-sensitive mechanisms change with age and stimulus spatial frequency
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DOI：
10.1016/j.visres.2011.11.004
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发表时间：
2012-01-15
期刊：
影响因子：
1.8
通讯作者：
Bennett, Patrick J.
中科院分区：
文献类型：
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作者：
Betts, Lisa R.;Sekuler, Allison B.;Bennett, Patrick J.
在灵长类动物视皮层中，视觉神经元感受野的经典区（CRF）和非经典区（nCRF）之间存在着对比度依赖的相互作用。描述单个神经元中CRF和nCRF相互作用的生理模型最近已被应用于年轻成人运动感知中的空间总和和抑制的心理物理测量（Tadin & Lappin，2005）。我们希望确定这样的模型是否可以解释在正常老化中发生的空间抑制的减少（Betts等人，2005年）。我们应用三种模型的持续时间阈值获得在一个简单的运动辨别任务，使用漂移的Gabor刺激，范围从0.5到4 C/deg的空间频率。我们发现，在一个模型中，中央CRF和周围的nCRF表示为空间重叠的兴奋性和抑制性的2D高斯与独立的对比度响应函数，我们称之为增益模型，可以简单地通过增加CRF的空间范围来解释衰老的影响。对另外两种型号进行了评价。大小模型，它改变了CRF的大小作为对比度的函数，产生CRF和nCRF的大小常数，显着偏离生理估计的感受野大小。驱动模型将抑制性nCRF的激活与CRF反应结合起来，对数据进行了合理拟合，并表明nCRF的抑制强度与年龄相关。然而，Drive模型估计CRF尺寸参数等于或甚至略大于nCRF尺寸参数，这与生理学文献不一致。因此，我们的研究结果表明，增益模型提供了最合理的估计感受野的大小。基于这个模型，年龄相关的增加，中央兴奋性感受野的大小相对于抑制周围可能有助于减少空间抑制的行为措施，发现在老年观察员。(C)2011爱思唯尔有限公司保留所有权利。
Contrast-dependent interactions between classical (CRF) and non-classical regions (nCRF) of visual neuron receptive fields are well documented in primate visual cortex. Physiological models that describe CRF and nCRF interactions in single neurons have recently been applied to psychophysical measures of spatial summation and suppression in motion perception of young adults (Tadin & Lappin, 2005). We wished to determine whether such models could account for the reduction in spatial suppression that occurs in normal aging (Betts et al., 2005). We applied three models to duration thresholds obtained in a simple motion discrimination task using drifting Gabor stimuli that ranged in Spatial frequency from 0.5 to 4 c/deg. We found that a model in which the center CRF and surrounding nCRF are represented as spatially-overlapping excitatory and inhibitory 2D Gaussians with independent contrast response functions, which we call the Gain model, could account for the effects of aging simply by increasing the spatial extent of the CRF. Two additional models were evaluated. The Size model, which varied the size of the CRF as a function of contrast, produced CRF and nCRF size constants that departed significantly from physiological estimates of receptive field sizes. The Drive model, which yoked the activation of the suppressive nCRF to the CRF response, yielded reasonable fits to the data and suggested an age-related decline in the strength of suppression from the nCRF. However, the Drive model estimated the CRF size parameter to be equal to, or even slightly larger than, the nCRF size parameter, which is inconsistent with the physiological literature. Our findings therefore suggest that the Gain model provides the most plausible estimates of receptive field sizes. Based on this model, age-related increases in the size of central excitatory receptive fields relative to the inhibitory surrounds may contribute to behavioral measures of reduced spatial suppression found in older observers. (C) 2011 Elsevier Ltd. All rights reserved.