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unexpectedtech:

Being able to switch neurons on and off and monitor how they communicate with one another is crucial for understanding and, ultimately, treating a host of brain disorders, including Parkinson’s disease, Alzheimer’s, and even psychiatric disorders such as severe depression.

Doctors and researchers today commonly use electrodes — on the scalp or implanted within the brain — to deliver zaps of electricity to stimulate cells. Unfortunately, these electrodes activate huge swaths of neural territory, made up of thousands or even millions of cells, of many different types. That makes it impossible to tease out the behavior of any given cell, or even of particular cell types, to understand cellular communication and how it contributes to the disease process.

Ideally, nerve cells would be activated in a non-invasive way that is also highly targeted. A promising method for doing this is photostimulation — essentially, controlling cells with light. Stanford University researchers and other have used altered mammalian nerve cells to carry light-sensitive proteins from single-celled algae, allowing the scientists to rapidly flip the cells on and off, just with flashes of light (optogenetics). The problem with this process, however, is that the light-controlled cells must be genetically altered.

An alternative, says the UW team, led by electrical engineer Lih Y. Lin and biophysicist Fred Rieke, is to use quantum dots, which confine electrons within three spatial dimensions. When these otherwise trapped electrons are excited by electricity, they emit light, but at very precise wavelengths, determined both by the size of the quantum dot and the material from which it is made. Because of this specificity, quantum dots are being explored for a variety of applications, including in lasers, optical displays, solar cells, light-emitting diodes, and even medical imaging devices.