page_title: Brainbow
section_title: History and development
hierarchical_section_title: Brainbow / History and development
caption_attribution_description: English: Mouse neurons labeled with fluorescent tags. Such “color coded” brain cells promise new solutions to formerly intractable problems with resolving closely packed neurons and tracing their axons and dendrites reliably over long distances. It seems unlikely that neural information processing will ever be understood without solving such problems and reconstructing circuits in far more detail that presently possible.
context_page_description: Brainbow is a process by which individual neurons in the brain can be distinguished from neighboring neurons using fluorescent proteins. By randomly expressing different ratios of red, green, and blue derivatives of green fluorescent protein in individual neurons, it is possible to flag each neuron with a distinctive color. This process has been a major contribution to the field of connectomics, traditionally known as hodology, which is the study of neural connections in the brain.
  The technique was originally developed in 2007 by a team led by Jeff W. Lichtman and Joshua R. Sanes, both at Harvard University. The original technique has recently been adapted for use with other model organisms including Drosophila melanogaster, Caenorhabditis elegans, and Arabidopsis thaliana.
  While earlier labeling techniques allowed for the mapping of only a few neurons, this new method allows more than 100 differently mapped neurons to be simultaneously and differentially illuminated in this manner. The resulting images can be quite striking and have won awards in science photography competitions.
context_section_description: The Brainbow neuroimaging technique was initially developed by a team of researchers at Harvard University in 2007. At the time they were working at Washington University in St. Louis. This particular group of scientists was led by professors Jeff W. Lichtman and Joshua R. Sanes, both of whom specialize in molecular and cellular biology and are highly renowned for their work.  The team constructed Brainbow using a two-step process: first, a specific genetic construct was generated that could be recombined in multiple arrangements to produce one of either three or four colors based on the particular fluorescent proteins (XFPs) being implemented.  Next, multiple copies of the same transgenic construct were inserted into the genome of the target species, resulting in the random expression of different XFP ratios and subsequently causing different cells to exhibit a variety of colorful hues.
  Brainbow was originally created as an improvement over more traditional neuroimaging techniques, such as Golgi staining and dye injection, both of which presented severe limitations to researchers in their ability to visualize the intricate architecture of neural circuitry in the brain.  While older techniques were only able to stain cells with a constricted range of colors, often utilizing bi- and tri-color transgenic mice to unveil limited information in regards to neuronal structures, Brainbow is much more flexible in that it has the capacity to fluorescently label individual neurons with up to approximately 100 different hues so that scientists can identify and even differentiate between dendritic and axonal processes.  By revealing such detailed information about neuronal connectivity and patterns, sometimes even in vivo, scientists are often able to infer information regarding neuronal interactions and their subsequent impact upon behavior and function.  Thus, Brainbow filled the void left by previous neuroimaging methods.
  With the recent advent of Brainbow in neuroscience, researchers are now able to construct specific maps of neural circuits and better investigate how these relate to various mental activities and their connected behaviors (i.e. Brainbow reveals information about the interconnections between neurons and their subsequent interactions that affect overall brain functionality).  As a further extrapolation of this method, Brainbow can therefore also be used to study both neurological and psychological disorders by analyzing differences in neural maps.
caption: A brainbow of mouse neurons from Smith, 2007
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