Developmental Biology, Institute of Biology 1, Faculty of Biology, Albert-Ludwigs-University Freiburg, Hauptstrasse 1, 79104 Freiburg, Germany; Centre for Biological Signalling Studies (BIOSS), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany.
Developmental Biology, Institute of Biology 1, Faculty of Biology, Albert-Ludwigs-University Freiburg, Hauptstrasse 1, 79104 Freiburg, Germany; Centre for Biological Signalling Studies (BIOSS), Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany.
Curr Biol. 2017 Feb 6;27(3):318-333. doi: 10.1016/j.cub.2016.11.059. Epub 2017 Jan 12.
The vertebrate diencephalic A11 system provides the sole dopaminergic innervation of hindbrain and spinal cord and has been implicated in modulation of locomotion and sensory processes. However, the exact contributions of sensory stimuli and motor behavior to A11 dopaminergic activity remain unclear. We recorded cellular calcium activity in four anatomically distinct posterior tubercular A11-type dopaminergic subgroups and two adjacent hypothalamic dopaminergic groups in GCaMP7a-transgenic, semi-restrained zebrafish larvae. Our analyses reveal the contributions of different sensory modalities and motor states to dopaminergic activity. Each posterior tubercular and hypothalamic subgroup showed distinct activity patterns, while activity was synchronous within individual subgroups. Caudal and dorsomedial hypothalamic dopaminergic neurons are activated following vigorous tail movements and stay active for about 10 s, revealing predominantly post-motor activity. In contrast, posterior tubercular dopaminergic neurons are predominantly sensory driven, with subgroups differentially responding to different tactile or visual sensory modalities. In the anterior subgroups, neuronal response magnitudes are tuned to tactile stimulus intensities, revealing features similar to sensory systems. We identify the lateral line system as source for this tactile tuning. In contrast, the posterior subgroup is responsive to distinct moving visual stimuli. Specifically, translational forward stimuli, which may indicate insufficient rheotaxis and drift, induce dopaminergic activity, but backward or rotational stimuli not. The activation of posterior tubercular dopaminergic neurons by sensory stimuli, and their projections onto peripheral mechanosensory systems, suggests a participation of A11-type neurons in the feedback regulation of sensory systems. Together with the adjacent hypothalamic neurons, they may serve to set basic behavioral states.
脊椎动物的间脑 A11 系统为后脑和脊髓提供了唯一的多巴胺能神经支配，并被认为参与了运动和感觉过程的调节。然而，感觉刺激和运动行为对 A11 多巴胺能活性的确切贡献仍不清楚。我们在 GCaMP7a 转基因、半约束斑马鱼幼虫中记录了四个解剖上不同的后结节 A11 型多巴胺能亚群和两个相邻下丘脑多巴胺能亚群的细胞钙活性。我们的分析揭示了不同感觉模态和运动状态对多巴胺能活性的贡献。每个后结节和下丘脑亚群都显示出不同的活动模式，而在单个亚群内活动是同步的。强烈的尾部运动后，尾侧和背内侧下丘脑多巴胺能神经元被激活，并保持大约 10 s 的活跃状态，主要表现为运动后活动。相比之下，后结节多巴胺能神经元主要受感觉驱动，不同的亚群对不同的触觉或视觉感觉模态有不同的反应。在前亚群中，神经元的反应幅度被触觉刺激强度调谐，显示出与感觉系统相似的特征。我们确定侧线系统是这种触觉调谐的来源。相比之下，后亚群对不同的运动视觉刺激有反应。具体来说，平移向前的刺激，这可能表明不足的趋流性和漂移，诱导多巴胺能活性，但向后或旋转的刺激不诱导。感觉刺激对后结节多巴胺能神经元的激活及其对周围机械感觉系统的投射表明 A11 型神经元参与了感觉系统的反馈调节。与相邻的下丘脑神经元一起，它们可能有助于设定基本的行为状态。
