Lamaze Angélique, Stanewsky Ralf
Institut für Neuro und Verhaltensbiologie, Westfälische Wilhelms University, Münster, Germany.
Front Physiol. 2020 Jan 8;10:1540. doi: 10.3389/fphys.2019.01540. eCollection 2019.
is a powerful genetic model to study the circadian clock. Recently, three drosophilists received the Nobel Prize for their intensive past and current work on the molecular clockwork (Nobel Prize 2017). The brain clock is composed of about 150 clock neurons distributed along the lateral and dorsal regions of the protocerebrum. These clock neurons control the timing of locomotor behaviors. In standard light-dark (LD) conditions (12-12 h and constant 25°C), flies present a bi-modal locomotor activity pattern controlled by the clock. Flies increase their movement just before the light-transitions, and these behaviors are therefore defined as anticipatory. Two neuronal oscillators control the morning and evening anticipation. Knowing that the molecular clock cycles in phase in all clock neurons in the brain in LD, how can we explain the presence of two behavioral activity peaks separated by 12 h? According to one model, the molecular clock cycles in phase in all clock neurons, but the neuronal activity cycles with a distinct phase in the morning and evening oscillators. An alternative model takes the environmental condition into consideration. One group of clock neurons, the dorso-posterior clock neurons DN1p, drive two peaks of locomotor activity in LD even though their neuronal activity cycles with the same phase (late night/early morning). Interestingly, the locomotor outputs they control differ in their sensitivity to light and temperature. Hence, they must drive outputs to different neuropil regions in the brain, which also receive different inputs. Since 2010 and the presentation of the first specific DN1p manipulations, many studies have been performed to understand the role of this group of neurons in controlling locomotor behaviors. Hence, we review what we know about this heterogeneous group of clock neurons and discuss the second model to explain how clock neurons that oscillate with the same phase can drive behaviors at different times of the day.
是研究生物钟的强大遗传模型。最近，三位果蝇学家因其过去和当前在分子生物钟机制方面的深入研究而获得诺贝尔奖（2017年诺贝尔奖）。大脑生物钟由大约150个时钟神经元组成，这些神经元分布在原脑的外侧和背侧区域。这些时钟神经元控制着运动行为的时间。在标准的明暗（LD）条件下（12小时光照 - 12小时黑暗，温度恒定在25°C），果蝇呈现出由生物钟控制的双峰运动活动模式。果蝇在光照转换前增加运动，因此这些行为被定义为预期行为。两个神经元振荡器控制早晨和傍晚的预期行为。已知在LD条件下，分子生物钟在大脑中所有时钟神经元中同步循环，那么我们如何解释存在两个相隔12小时的行为活动峰值呢？根据一种模型，分子生物钟在所有时钟神经元中同步循环，但神经元活动在早晨和傍晚振荡器中具有不同的相位循环。另一种模型考虑了环境条件。一组时钟神经元，即背侧后时钟神经元DN1p，在LD条件下驱动运动活动的两个峰值，尽管它们的神经元活动在相同相位（深夜/凌晨）循环。有趣的是，它们控制的运动输出对光和温度的敏感度不同。因此，它们必须将输出驱动到大脑中不同的神经纤维区域，这些区域也接收不同的输入。自2010年首次进行特定的DN1p操作以来，已经进行了许多研究以了解这组神经元在控制运动行为中的作用。因此，我们回顾了我们对这一异质时钟神经元群体的了解，并讨论了第二种模型，以解释相位相同的时钟神经元如何在一天中的不同时间驱动行为。
