Comparison of photopic negative response measurements in the time and time-frequency domains.
Comparison of photopic negative response measurements in the time and time-frequency domains.
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DOI：
10.1007/s10633-016-9558-6
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发表时间：
2016-10
影响因子：
1.4
通讯作者：
McAnany, J. Jason
中科院分区：
文献类型：
--
作者：
Kundra, Hansa;Park, Jason C.;McAnany, J. Jason
使用时间和时频域分析比较全视野明视负反应（PhNR）的测量值以及PhNR的受试者内变化。记录了20名正常视力受试者（年龄24至65岁）的全视野ERG，这些受试者由长波长脉冲（3 cd s m-2）和短波长适应场（12.5 cd m-2）引起。从每个受试者获得3至10个波形，并使用PhNR的标准时域分析以及离散小波变换（DWT）来分析每个波形，以提取对应于PhNR的时频分量。推导并比较了PhNR的三种不同测量：1）PhNR谷值处的振幅; 2）刺激开始后72 ms处的振幅; 3）对应于PhNR的11 Hz、60至120 ms DWT频率箱中的能量。此外，还评价了每项指标通过b波使PhNR正常化的效果。计算每个定义的变异系数（CV），以评价受试者内变异。在谷值和72 ms处测量的PhNR幅度显著相关（r = 0.88，p < 0.001）。此外，通过DWT导出的PhNR能量与在谷值（r = 0.64，p = 0.002）和72 ms（r = 0.60，p = 0.005）处测量的振幅显著相关。谷值、72 ms和DWT测量值的平均（± SD）受试者内CV分别为26%（15%）、49%（26%）和30%（15%）。b波振幅（即PhNR/B）的标准化对受试者内CV的影响最小，而b波和PhNR振幅之和（即PhNR/[B+PhNR]）的标准化显著降低了所有三项测量的CV（所有条件下的平均CV均小于17%）。虽然每种PhNR定义都有优点和缺点，但所有三个指标都提供了类似的PhNR估计值。然而，受试者内CV对于在72 ms时进行的测量相对较高，表明基于固定时间点的定义可能会引入变异性。在某些条件下，通过PhNR和b波振幅之和进行归一化后，受试者内变异的显著降低可能是有利的。
To compare measurements of the full-field photopic negative response (PhNR), as well as intra-subject variation in the PhNR, using time and time-frequency domain analyses. Full-field ERGs were recorded from 20 normally-sighted subjects (ages 24 to 65 years) elicited by a long-wavelength pulse (3 cd s m−2) presented against a short wavelength adapting field (12.5 cd m−2). Three to 10 waveforms were obtained from each subject and each waveform was analyzed using standard time domain analyses of the PhNR, as well as a discrete wavelet transform (DWT) to extract time-frequency components that correspond to the PhNR. Three different measures of the PhNR were derived and compared: 1) amplitude at the PhNR trough; 2) amplitude at 72 ms following stimulus onset; 3) energy in the 11 Hz, 60 to 120 ms DWT frequency bin that corresponds to the PhNR. In addition, the effect of normalizing the PhNR by the b-wave was evaluated for each of the measures. Coefficients of variation (CVs) were computed for each definition to evaluate intra-subject variation. PhNR amplitudes measured at the trough and at 72 ms were significantly correlated (r = 0.88, p < 0.001). Additionally, PhNR energy derived by DWT was significantly correlated with the amplitude measured at the trough (r = 0.64, p = 0.002) and at 72 ms (r = 0.60, p = 0.005). Mean (± SD) intra-subject CVs were 26% (15%), 49% (26%), and 30% (15%), for measures at the trough, 72 ms, and DWT, respectively. Normalization by the b-wave amplitude (i.e. PhNR/b) had minimal effect on the intra-subject CVs, whereas normalization by the sum of the b-wave and PhNR amplitudes (i.e. PhNR/[b+PhNR]) substantially reduced the CVs for all three measures (mean CVs were less than 17% for all conditions). Although each PhNR definition has advantages and disadvantages, all three metrics provide similar estimates of the PhNR. Intra-subject CVs, however, were relatively high for measurements made at 72 ms, indicating that definitions based on a fixed time-point may introduce variability. The substantial decrease in intra-subject variation after normalization by the sum of the PhNR and b-wave amplitudes may be advantageous under some conditions.
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