Visualizing the Distribution of Synapses from Individual Neurons in the Mouse Brain

PLoS One

Liqun Luo¹  Kristina D. Micheva¹  Stephen J. Smith²  Ling Li²  Bosiljka Tasic²  Vsevolod M. Ivanov²  Maria L. Spletter³ 

[1] Department of Molecular and Cellular Physiology, Stanford University, Stanford, California, United States of America;Howard Hughes Medical Institute, Department of Biology, Stanford University, Stanford, California, United States of America;Lynbrook High School, San Jose, California, United States of America

关键词: Synapses;    Axons;    Neurons;    Neuronal dendrites;    Presynaptic terminals;    Purkinje cells;    Granule cells;    Fluorescence imaging;   

DOI  :  10.1371/journal.pone.0011503

学科分类：医学（综合）

来源: Public Library of Science

【 摘 要 】

Background Proper function of the mammalian brain relies on the establishment of highly specific synaptic connections among billions of neurons. To understand how complex neural circuits function, it is crucial to precisely describe neuronal connectivity and the distributions of synapses to and from individual neurons.Methods and Findings In this study, we present a new genetic synaptic labeling method that relies on expression of a presynaptic marker, synaptophysin-GFP (Syp-GFP) in individual neurons in vivo. We assess the reliability of this method and use it to analyze the spatial patterning of synapses in developing and mature cerebellar granule cells (GCs). In immature GCs, Syp-GFP is distributed in both axonal and dendritic regions. Upon maturation, it becomes strongly enriched in axons. In mature GCs, we analyzed synapses along their ascending segments and parallel fibers. We observe no differences in presynaptic distribution between GCs born at different developmental time points and thus having varied depths of projections in the molecular layer. We found that the mean densities of synapses along the parallel fiber and the ascending segment above the Purkinje cell (PC) layer are statistically indistinguishable, and higher than previous estimates. Interestingly, presynaptic terminals were also found in the ascending segments of GCs below and within the PC layer, with the mean densities two-fold lower than that above the PC layer. The difference in the density of synapses in these parts of the ascending segment likely reflects the regional differences in postsynaptic target cells of GCs.Conclusions The ability to visualize synapses of single neurons in vivo is valuable for studying synaptogenesis and synaptic plasticity within individual neurons as well as information flow in neural circuits.

【 授权许可】

CC BY