Over ten years ago, the first light-sensitive
proteins derived from microbial opsins were injected into specific areas of the
brain to manipulate neuronal activity. Depending on the properties of the
opsins, they can either stimulate or inhibit a colony of neurons in response to
light. This technique, known as Optogenetics, was a breakthrough for
Neuroscientists. This method not only proves that we are capable of controlling
cell action without the use of invasive electrodes, but can also show how behavior
changes when a specific brain region is turned “on” or “off.” Many optogenetic
studies that have been done in the past refer to the activation of a group of
cells in a specific location in the brain, but this recent article: “Next-Generation
Optogenetic Molecules Control Single Neurons,” written by Anne Trafton, a new
method is introduced for targeting only one neuron at a time.
Scientists at MIT and Paris Descartes University
developed a new, more powerful, light-sensitive proteins along with “holographic
light-shaping that can focus light on a single cell” (Trafton). Many
optogenetic studies include a large light that shines over a group of neurons,
but in single-cell optogenetics, the light shape is reduced to just a width of 2-photons!
This allows us to have precise, independent, and localized control over which
neuron is getting stimulated, as well as excellent timing of the activation –
responding consistently every time, and variability less than a millisecond.
With this discovery, we can learn more about the
way neurons are connected to each other, in questioning if a neighboring neuron
is controlling the other or if it receives stimulation from other signals far
away. A professor at the Institute of Neurology in London is planning on using single-cell
optogenetics in his studies of “diseases caused by mutations of proteins
involved in synaptic communication between neurons” (Trafton). The more
advancements in optogenetics technology, the more we can start to see how one
single neuron can change a behavior. Soon enough, we might be able to determine
what exactly a thought or feeling actually is.
The implications of this technique are vast, yet one exciting advancement in particular sticks out to me. I wonder if the ability to stimulate only one neuron at a time and study its inputs and outputs will eventually make it possible to create a detailed functional map of individual neurons in the brain of model organisms! This could hugely elevate our understanding of how exactly signals travel in the brain, and as you mentioned, could be immensely helpful in disease treatment. I hope to see more research utilizing this technique in the future, and possibly some advancements made to bring optogenetics into human trials.
ReplyDeleteIt was interesting to see how optogenetics has been able to go from a colony of neurons being stimulated by light to being able to stimulate a single neuron at a time. This allows us to stimulate a neuron without using invasive electrodes while still having the precision to locate the correct neuron. As you mentioned, the temporal resolution is astonishingly accurate as well with the variability being less than a millisecond. It will be interesting to see if we could apply this to learn about neural networks as well as terminal diseases such as cancer. If we could target the malignant growths of cells with optogenetics, it could even be the gateway to the cure for cancer.
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