Takahashi J S, Menaker M
J Neurosci. 1982 Jun;2(6):815-28. doi: 10.1523/JNEUROSCI.02-06-00815.1982.
The suprachiasmatic nuclei (SCN) of the hypothalamus are necessary for the persistence of free running circadian activity rhythms in house sparrows. Suprachiasmatic lesions abolish circadian locomotor rhythms in constant darkness. The locomotor activity of lesioned sparrows was analyzed with two different power spectral analysis methods and was found to be arrhythmic. There was a weak correlation between the extent of damage to the SCN and the relative amplitude of the power spectral density in the circadian frequency range. In light-dark cycles (LD 12:12), the locomotor behavior of lesioned sparrows was rhythmic and similar to that of intact birds. However, entrainment was disrupted in SCN-lesioned sparrows exposed to a short photoperiod light cycle (LD 1:24). These results demonstrate that the SCN are crucial for the generation of overt circadian rhythmicity in birds. The fact that SCN lesions abolish circadian rhythms in sparrows and several mammalian species suggests that vertebrate circadian organization may be based on differentially weighted interactions among the pineal, the SCN, and perhaps other brain regions.
下丘脑的视交叉上核（SCN）对于家麻雀自由运行的昼夜节律活动的持续存在是必需的。视交叉上核损伤会消除在持续黑暗中的昼夜运动节律。用两种不同的功率谱分析方法分析了损伤麻雀的运动活动，发现其无节律。SCN损伤程度与昼夜频率范围内功率谱密度的相对幅度之间存在微弱的相关性。在明暗周期（LD 12:12）中，损伤麻雀的运动行为有节律，且与完整鸟类相似。然而，暴露于短光周期光循环（LD 1:24）的SCN损伤麻雀的昼夜节律被破坏。这些结果表明，SCN对于鸟类明显的昼夜节律性的产生至关重要。SCN损伤会消除麻雀和几种哺乳动物的昼夜节律这一事实表明，脊椎动物的昼夜节律组织可能基于松果体、SCN以及或许其他脑区之间不同权重的相互作用。
