By James Cavuoto, editor
October 5, 2026 | A new high-speed microscope from MIT could give neuroscientists a more direct way to observe how neurons communicate across an entire brain—an advance with implications for basic neuroscience, neurotechnology tool development, and future efforts to map distributed neural circuits in real time.
The system, adapted for fast, high-volumetric-rate imaging, allowed researchers to track electrical activity across the zebrafish brain on a millisecond timescale. In demonstrations, the microscope revealed brain-wide patterns of neural activity triggered by ultraviolet light, capturing signals that conventional calcium imaging techniques can miss.
“All of the parts of the brain are connected together, so if you want to truly understand the brain, you have to understand how all the neurons work together as an emergent whole,” said Ed Boyden, the Y. Eva Tan Professor in Neurotechnology at MIT; a professor of biological engineering, media arts and sciences, and brain and cognitive sciences; and a member of MIT’s McGovern Institute for Brain Research, Yang Tan Collective, and the Koch Institute for Integrative Cancer Research.
Boyden is senior author of the study, which appears in Nature Methods (DOI: 10.1038/s41592-026-03179-7). Former J. Douglas Tan Postdoctoral Fellow Zeguan Wang and former MIT research scientist Jie Zhang are lead authors of the paper.
For years, neuroscientists have relied heavily on calcium imaging to infer neural activity. The method is powerful, but it is indirect: calcium ions enter neurons after electrical impulses, making calcium signals a proxy for firing activity. That delay can make it difficult to observe fast, single-spike events across large neural populations.
“Calcium imaging inherently is very slow, so you’re talking about imaging activity on the order of seconds or even minutes,” Zhang said. “Typically that is too slow for us to be able to see a lot of these high-speed neural activities. Neurons compute using electrical activity, so with voltage imaging, you can get direct observation of that.”
The MIT team’s approach builds on genetically encoded voltage indicators—fluorescent proteins that can be expressed in neurons and report electrical impulses through changes in fluorescence. Previous efforts using these indicators have generally focused on small groups of neurons or localized brain regions. The challenge has been to scale voltage imaging to whole-brain volumes while retaining the speed needed to resolve millisecond-scale neural events.
To reach that scale, the researchers modified a light sheet microscope, which uses a sheet of laser light to illuminate thin slices of a sample and assemble three-dimensional images. Standard light sheet systems can cover large volumes, but not fast enough to capture single-neuron voltage dynamics across an entire brain. MIT’s implementation increased camera acquisition speed and used remote refocusing to accelerate volumetric scanning.
“Different groups of neurons that are distributed across the brain coordinate together at millisecond timescales to generate a lot of behaviors and brain computations,” Wang said. “To understand the principles, we need the technology to observe their activity at the same time, across the whole brain, so we are not missing any important participant neurons.”
The resulting platform can scan the entire zebrafish brain 200 times per second—once every five milliseconds—giving investigators a view of neural dynamics that is both brain-wide and fast enough to follow electrical signaling.
In larval zebrafish, the researchers engineered neurons to express Positron2-Kv, a voltage indicator. Although the signal was not present in every neuron, roughly one quarter of neurons produced usable signals—enough to observe brain-wide activity patterns, including single voltage spikes and rapid spike bursts during resting states.
When the fish were exposed to ultraviolet light, the microscope captured activity in the optic tectum, which receives and processes visual input from the retina. The activity then propagated across the tectum. The system also detected spontaneous activity sequences across sets of neurons in the cerebellum and hindbrain, suggesting that the platform could help researchers identify how distributed circuits coordinate during sensory processing and behavior.
The team is now working to increase the percentage of neurons that can be imaged across the brain, while also improving the microscope’s speed and resolution. They also hope to extend the approach to other experimental models, including mice—an important step if the technology is to become broadly useful for neurotechnology developers and neuroscience labs studying larger and more complex nervous systems.
More immediately, the work could provide a new hypothesis-generation tool for systems neuroscience. By allowing researchers to see how neurons distributed across a brain participate in fast network events, the microscope may help reveal how brain activity relates to behavior, sensory processing, and internal states.
“A big question is simply to understand how neurons work together as a network. And this might be the first time that you could do that, because you can image the voltage of neurons distributed throughout the network,” Boyden said.
