SENSITIVITY AND INTEGRATION IN A VISUAL PATHWAY FOR CIRCADIAN ENTRAINMENT IN THE HAMSTER (MESOCRICETUS-AURATUS)
SENSITIVITY AND INTEGRATION IN A VISUAL PATHWAY FOR CIRCADIAN ENTRAINMENT IN THE HAMSTER (MESOCRICETUS-AURATUS)
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DOI：
10.1113/jphysiol.1991.sp018660
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发表时间：
1991-07-01
影响因子：
5.5
通讯作者：
TAKAHASHI, JS
中科院分区：
文献类型：
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作者：
NELSON, DE;TAKAHASHI, JS
1. 光诱导的相位变化的昼夜节律的车轮运行活动被用来测量光敏感性的昼夜节律起搏器和视觉通路，传达光信息，它在金黄仓鼠（Mesocricetus auratus）。 通过测量对不同辐照度和持续时间的光刺激的相移响应的幅度来评估对刺激辐照度和持续时间的敏感性。 在昼夜节律的三个不同阶段测量视觉敏感度. 在不同的昼夜节律相位测量的刺激-响应曲线表明，最大相移是视觉响应度作为昼夜节律的函数变化的唯一方面。 刺激-反应曲线的半饱和常数（sigma）在测试的三个昼夜节律相位上没有显著差异。 光对辐照度的敏感性（1/sigma）似乎在昼夜节律中保持恒定。 仓鼠的昼夜节律起搏器和光感受系统，使它更敏感的辐照度较长的持续时间的刺激比辐照度较短的刺激。 该系统对300 s和更长持续时间的刺激的辐照度最敏感。 提出了一个定量模型来解释发生在刺激-响应曲线作为光刺激持续时间的函数的变化. 仓鼠昼夜节律起搏器的光刺激阈值也相当高。 对于最佳刺激持续时间，阈值辐照度（诱导统计学显著反应所需的最小辐照度）约为10（11）光子cm-2 s-1。 该阈值相当于0.1 cd m-2.5的角膜处的亮度。 我们还测量了这种视觉通路对刺激中光子总数的敏感性。 该系统对持续时间在30和3600 s之间的刺激中的光子最敏感。 光积分的最大量子效率出现在300 s刺激. 这些结果表明，传递光信息的哺乳动物昼夜节律起搏器的视觉通路具有几个独特的特点。 这些路径对光辐照度相对不敏感，并且还在相对长的持续时间内整合光输入。 因此，这种视觉系统对持续几分钟的刺激中传递的总光子具有最佳的“调谐”灵敏度。 这些特征一起可能使该视觉系统对环境“噪声”无反应，环境“噪声”会干扰昼夜节律对明暗周期的夹带。
1. Light-induced phase shifts of the circadian rhythm of wheel-running activity were used to measure the photic sensitivity of a circadian pacemaker and the visual pathway that conveys light information to it in the golden hamster (Mesocricetus auratus). The sensitivity to stimulus irradiance and duration was assessed by measuring the magnitude of phase-shift responses to photic stimuli of different irradiance and duration. The visual sensitivity was also measured at three different phases of the circadian rhythm.2. The stimulus-response curves measured at different circadian phases suggest that the maximum phase-shift is the only aspect of visual responsivity to change as a function of the circadian day. The half-saturation constants (sigma) for the stimulus-response curves are not significantly different over the three circadian phases tested. The photic sensitivity to irradiance (1/sigma) appears to remain constant over the circadian day.3. The hamster circadian pacemaker and the photoreceptive system that subserves it are more sensitive to the irradiance of longer-duration stimuli than to irradiance of briefer stimuli. The system is maximally sensitive to the irradiance of stimuli of 300 s and longer in duration. A quantitative model is presented to explain the changes that occur in the stimulus-response curves as a function of photic stimulus duration.4. The threshold for photic stimulation of the hamster circadian pacemaker is also quite high. The threshold irradiance (the minimum irradiance necessary to induce statistically significant responses) is approximately 10(11) photons cm-2 s-1 for optimal stimulus durations. This threshold is equivalent to a luminance at the cornea of 0.1 cd m-2.5. We also measured the sensitivity of this visual pathway to the total number of photons in a stimulus. This system is maximally sensitive to photons in stimuli between 30 and 3600 s in duration. The maximum quantum efficiency of photic integration occurs in 300 s stimuli.6. These results suggest that the visual pathways that convey light information to the mammalian circadian pacemaker possess several unique characteristics. These pathways are relatively insensitive to light irradiance and also integrate light inputs over relatively long durations. This visual system, therefore, possesses an optimal sensitivity of 'tuning' to total photons delivered in stimuli of several minutes in duration. Together these characteristics may make this visual system unresponsive to environmental 'noise' that would interfere with the entrainment of circadian rhythms to light-dark cycles.