Researches have recently developed a tool that may help in mapping the neural networks of living organisms using light. Observing these electrical signals of neurons can lead to numerous advancements in our understanding of neural circuitry.
In a collaborative study between Viviana Gradinaru, Frances Arnold and Barbara Dickinson, they developed a method to sense neuronal activity with light. These researchers used a protein named Archaerhodopsin (Arch) and exploited its light responsive qualities. They were able to optimize Arch through a process known as directed evolution. Using this method they created a variant of the Arch protein, called archer1 that acted as a voltage sensor under a red light and an inhibitor under a green light, while generating a light intensive enough to detect. When this protein acts as a voltage sensor it can show which neurons are active and synaptically connected and which aren’t under certain stimuli.
These researchers were able to test Archer1 in the worm C. elegans, which was chosen for its near transparent tissue that made it ideal for observing the luminescent protein. This was the first place they were able to observe the circuits of the neurons light up if they were expressed and dim down if they were repressed. For future studies they hope to make Archer1 bright enough to be detected through opaque tissue and accurate enough to detect voltage changed in more complex, behaving mammals. This study can prove to help us in our understanding of neural networks.
Original papers:
http://www.pnas.org/content/111/36/13034
http://www.nature.com/ncomms/2014/140915/ncomms5894/full/ncomms5894.html (You can only read abstracts; you have to pay to read the full text)
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