Babski Helene, Codianni Marcello, Bhandawat Vikas
School of Biomedical Engineering and Health Sciences, Drexel University, USA.
Heliyon. 2024 Apr 20;10(9):e29952. doi: 10.1016/j.heliyon.2024.e29952. eCollection 2024 May 15.
Projection neurons that communicate between different brain regions and local neurons that shape computation within a brain region form the majority of all neurons in the brain. Another important class of neurons is neuromodulatory neurons; these neurons are in much smaller numbers than projection/local neurons but have a large influence on computations in the brain. Neuromodulatory neurons are classified by the neurotransmitters they carry, such as dopamine and serotonin. Much of our knowledge of the effect of neuromodulators comes from experiments in which either a large population of neuromodulatory neurons or the entire population is perturbed. Alternatively, a given neuromodulator is exogenously applied. While these experiments are informative of the general role of the neurotransmitter, one limitation of these experiments is that the role of individual neuromodulatory neurons remains unknown. In this study, we investigate the role of a class of octopaminergic (octopamine is the invertebrate equivalent of norepinephrine) neurons in or fruit fly. Neuromodulation in work along similar principles as humans; and the smaller number of neuromodulatory neurons allow us to assess the role of individual neurons. This study focuses on a subpopulation of octopaminergic descending neurons (OA-DNs) whose cell bodies are in the brain and project to the thoracic ganglia. Using in-vivo whole-cell patch-clamp recordings and anatomical analyses that allow us to compare light microscopy data to the electron microscopic volumes available in the fly, we find that neurons within each cluster have similar physiological properties, including their relation to locomotion. However, neurons in the same cluster with similar anatomy have very different connectivity. Our data is consistent with the hypothesis that each OA-DN is recruited individually and has a unique function within the fly's brain.
在不同脑区之间传递信息的投射神经元以及在一个脑区内塑造计算功能的局部神经元构成了大脑中所有神经元的主体。另一类重要的神经元是神经调质神经元；这类神经元的数量比投射/局部神经元少得多，但对大脑中的计算有很大影响。神经调质神经元根据它们所携带的神经递质进行分类，比如多巴胺和血清素。我们对神经调质作用的许多了解来自于这样的实验，即大量的神经调质神经元群体或整个群体受到干扰。或者，外源性地应用某种特定的神经调质。虽然这些实验有助于了解神经递质的一般作用，但这些实验的一个局限性在于单个神经调质神经元的作用仍然未知。在本研究中，我们调查了果蝇中一类章鱼胺能神经元（章鱼胺相当于脊椎动物中的去甲肾上腺素）的作用。果蝇中的神经调节作用遵循与人类相似的原理；而且神经调质神经元数量较少，这使我们能够评估单个神经元的作用。本研究聚焦于一群章鱼胺能下行神经元（OA-DNs），其细胞体位于大脑中并投射到胸神经节。通过使用体内全细胞膜片钳记录和解剖分析，使我们能够将光学显微镜数据与果蝇中可用的电子显微镜体积数据进行比较，我们发现每个簇内的神经元具有相似的生理特性，包括它们与运动的关系。然而，具有相似解剖结构的同一簇中的神经元具有非常不同的连接性。我们的数据与以下假设一致，即每个OA-DN都是单独被招募的，并且在果蝇大脑中具有独特的功能。
