BOLD fMRI response of early visual areas to perceived contrast in human amblyopia
BOLD fMRI response of early visual areas to perceived contrast in human amblyopia
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DOI：
10.1152/jn.2000.84.4.1907
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发表时间：
2000-10-01
影响因子：
2.5
通讯作者：
Menon, RS
中科院分区：
文献类型：
--
作者：
Goodyear, BG;Nicolle, DA;Menon, RS
在这项研究中，我们使用时间二选一强制选择心理物理程序来测量观察者对每只眼睛 22% 物理对比度光栅的感知，作为空间频率的函数，在四名单侧弱视受试者和六名视力正常的受试者中。还使用标准阶梯法测量对比度阈值。此外，血氧水平依赖性 (BOLD) 功能磁共振成像 (fMRI) 用于测量早期视觉皮层区域内的神经元对相同 22% 物理对比光栅的单眼呈现的神经元反应，作为空间频率的函数。对于所有六名视力正常的受试者和三名弱视受试者，心理物理学测量的作为空间频率函数的 22% 对比度感知对于双眼来说是相同的。然而，正如预期的那样，所有受试者的弱视眼的阈值对比度均升高。无论是否存在弱视，每只眼睛对“激活”体素内 22% 物理对比度的 fMRI 响应幅度都是相同的，作为空间频率的函数。然而，弱视刺激期间“激活”的功能磁共振成像体素总是比正常眼睛刺激期间少。这些结果与弱视患者对比度阈值升高的假设是一致的，因为在弱视刺激期间做出反应的神经元较少，并且反映对比度感知的反应神经元的平均放电率在弱视中不受影响。
In this study, we used a temporal two-alternative forced choice psychophysical procedure to measure the observer's perception of a 22% physical contrast grating for each eye as a function of spatial frequency in four subjects with unilateral amblyopia and in six subjects with normal vision. Contrast thresholds were also measured using a standard staircase method. Additionally, blood-oxygenation-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) was used to measure the neuronal response within early visual cortical areas to monocular presentations of the same 22% physical contrast gratings as a function of spatial frequency. For all six subjects with normal vision and for three subjects with amblyopia, the psychophysically measured perception of 22% contrast as a function of spatial frequency was the same for both eyes. Threshold contrast, however, was elevated for the amblyopic eye for all subjects, as expected. The magnitude of the fMRI response to 22% physical contrast within "activated" voxels was the same for each eye as a function of spatial frequency, regardless of the presence of amblyopia. However, there were always fewer "activated" fMRI voxels during amblyopic stimulation than during normal eye stimulation. These results are consistent with the hypotheses that contrast thresholds are elevated in amblyopia because fewer neurons are responsive during amblyopic stimulation, and that the average firing rate of the responsive neurons, which reflects the perception of contrast, is unaffected in amblyopia.