Scientists Capture Synaptic Transmission in a Live Animal for the First Time

Studying the neurons within a mammal can be difficult. Yet even more difficult is charting the chemical signals that neurons use to communicate to one another. Known as "synaptic transmission," this communication is critical for the brain and spinal cord to quickly process the huge amount of incoming stimuli. Now, though, researchers have observed and measured synaptic transmission in a live animal for the very first time.

In this case, the researchers used a technique called "optogenetics." This method uses light to precisely control the activity of specific neurons in living, even moving, animals in real time. This precision is critical in being able to study the hundreds of different neuron types, and understand higher brain functions such as thought, behavior, language, memory or even mental disorders.

Optogenetics works by inserting the gene of a light-sensitive protein into live neurons, from a single cell to an entire family of them. The genetically modified neurons then produce the light-sensitive protein, which sits on their outsides. There, it acts as a genetic channel and when light is shown on the neuron, the channel opens up and allows electrical ions to flow into the cell.

In this case, the researchers stimulated single neurons of anesthetized mice to see if the method could be used to record synaptic transmissions. It turns out that the researchers were correct and were both able to record and analyze the synaptic transmissions from light-sensitive neurons to interneurons.

Currently, the scientists are now aiming to explore other neuronal connections in the mouse barrel cortex. They also want to try the technique on mice that are awake to see how switching neuronal activity on and off with a light can affect higher brain functions.

The findings are published in the journal Neuron.

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