In our first installment of The Art of Neuroscience, a recurring online gallery series here at The Beautiful Brain that will feature outstanding images of the brain produced by science, we are given a taste of a newly developed neuron-staining technique that reveals entire, glowing networks of neurons. By using protein markers derived from the rabies virus, James Marshel, Takuma Mori, Kristina Nielsen and Edward Callaway, of The Salk Institute for Biological Studies in California, were able to label the networks of neurons each cell relies on to manage its activity. While neurons only have two destinies at a given moment – fire or don’t – they collect information from thousands of other neurons to make their decision.
The researchers were able to do this because of the nature of rabies – it follows a “retrograde” infection pathway, infecting one neuron and subsequently all the neurons giving it orders upstream. By using striking fluorescent dyes, Marshel et al labeled the rabies proteins and illuminated these webs of neurons:
“Each single neuronal network exists in a tangled web of as many as trillions of connections between billions of neurons spanning the entire brain, confounding attempts to identify detailed circuits and relate circuits to functions in vivo. We sought to overcome this logistical barrier and facilitate the direct analysis of the fine-scale structure and function of single neuronal networks by developing and validating a robust and reliable technique to target a single neuron and its monosynaptic inputs for independent gene expression and detailed cell labeling (Marshel et al, 2010).”
Images/ Marshel, James H., Mori, Takuma, Nielsen, Kristina J. and Callaway, Edward M. “Targeting Single Neuronal Networks for Gene Expression and Cell Labeling In Vivo,” Neuron. Vol. 67 Issue 4, (August 2010), Pages 562-574.