Finding ways to image neurons — the active nerve cells that transmit signals throughout our bodies — without interfering with their function has been difficult. For example, electrodes and fluorescent dyes employed to "see" a neuron's activity under a high-power microscope have the potential to skew results. What's more, these techniques also limit the number of neurons that can be studied at once, which hinders researchers' understanding of how the nerve cells work collectively.

But one research team from Switzerland says it has found a way to capture neuronal activities in real time without disturbing the cells themselves. They reported their results in the Journal of Neuroscience.

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The method, called digital holographic microscopy (DHM), is noninvasive, meaning it does not penetrate or modify the neuron. Instead of recording information using lenses, DHM relies on light to create holographic images that are modified by computer algorithms to be compared in real-time. The same method has been used by material scientists as well as biologists comparing phases of other living cells.


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In their analysis, researchers measured mice neurons' responses to glutamate and GABA — both common neurotransmitters in the brain — in a cell dish. Their goal was to determine whether DHM allowed them to see in real-time what happens to water and nutrient movement during cell signaling. The method proved useful in imaging neuron phases and activity within the cell.

In a press release, Pierre Magistretti, an author of the study, compares the imaging technique to determining a rock's shape in the ocean. The idea is that an object's shape and composition can be deduced by looking at how it distorts the waves of energy that hit it. During DHM, he says, a single laser wavelength can be aimed at a neuron and recorded as it reflects through the other side. Comparing the distorted wavelength with a reference one allows computer algorithms to build a picture of the cell.

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Yet its potential for drug testing is what makes using DHM on neurons exciting. This way, researchers can test drugs' interactions with petri-dish brain neurons and gauge their responses without tampering with the cells. He says the approach will be useful in finding new ways to test the effectiveness of drugs for neurodegenerative diseases such as Alzheimer's and Parkinson's.

Photo courtesy Lyncee Tec



Video courtesy EPFLNews