Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH, United States.
Neurosci Res. 2024 Jan;198:1-7. doi: 10.1016/j.neures.2023.06.009. Epub 2023 Jun 28.
How do neurons encode the information that underlies cognition, internal states, and behavior? This review focuses on the neural circuit mechanisms underlying sleep in Drosophila and, to illustrate the power of addressing neural coding in this system, highlights a specific circuit mediating the circadian regulation of sleep quality. This circuit exhibits circadian cycling of sleep quality, which depends solely on the pattern (not the rate) of spiking. During the night, the stability of spike waveforms enhances the reliability of spike timing in these neurons to promote sleep quality. During the day, instability of the spike waveforms leads to uncertainty of spike timing, which remarkably produces synaptic plasticity to induce arousal. Investigation of the molecular and biophysical basis of these changes was greatly facilitated by its study in Drosophila, revealing direct connections between genes, molecules, spike biophysical properties, neural codes, synaptic plasticity, and behavior. Furthermore, because these patterns of neural activity change with aging, this model system holds promise for understanding the interplay between the circadian clock, aging, and sleep quality. It is proposed here that neurophysiological investigations of the Drosophila brain present an exceptional opportunity to tackle some of the most challenging questions related to neural coding.
神经元如何编码认知、内部状态和行为的信息？本综述重点介绍了果蝇睡眠的神经回路机制，并通过阐明一个特定的调节睡眠质量的昼夜节律回路，说明了在该系统中解决神经编码的力量。该回路表现出睡眠质量的昼夜节律循环，这仅取决于尖峰的模式（而非速率）。在夜间，尖峰波形的稳定性增强了这些神经元中尖峰定时的可靠性，从而提高了睡眠质量。在白天，尖峰波形的不稳定性导致尖峰定时的不确定性，从而显著产生突触可塑性以引起觉醒。通过在果蝇中的研究，极大地促进了对这些变化的分子和生物物理基础的研究，揭示了基因、分子、尖峰生物物理特性、神经编码、突触可塑性和行为之间的直接联系。此外，由于这些神经活动模式随年龄而变化，这个模型系统有望理解昼夜节律钟、衰老和睡眠质量之间的相互作用。这里提出，对果蝇大脑的神经生理学研究为解决与神经编码相关的一些最具挑战性的问题提供了绝佳机会。
