Nine neuron types filmed simultaneously in living animals

Researchers have developed a method called Neuroplex. It combines two existing techniques: calcium imaging via a miniscope (a small wearable microscope mounted on a rodent’s head) and multiplexed confocal spectral imaging in living tissue. The result is that the researchers can simultaneously track nine distinct subgroups of neurons while an animal moves freely. All nine are visible through the same optical fiber lens.

This opens a new kind of experiment. Researchers can now observe which combinations of cell types are active during a specific behavior. Previously, they had to choose in advance: which two populations do we want to see? Now that choice is far less limiting. That increases the chance of detecting functional patterns that would otherwise remain invisible.

Relevant for aging research

Brain aging involves the loss of specific cell types and changes in communication between neuronal subnetworks. To understand that properly, you need to observe multiple populations at once. Until now that was technically impossible in a freely behaving animal. It was only feasible in brain slices outside the body or in anesthetized animals. Neuroplex moves that boundary.

The technique is also valuable for research into Alzheimer’s and Parkinson’s disease, where early changes in specific cell groups may play a role long before symptoms appear. By tracking those populations simultaneously in animal disease models, researchers can better map the sequence of decline.

What still needs work

The current version of Neuroplex has been tested in mice. Extending it to other animal models, and eventually to clinical applications in humans, requires further validation. Analyzing nine simultaneous signals also places high demands on computing power and software. As a methodological advance, however, this approach sets a new standard for in-vivo neuroscience.

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