Filming Nearly Every Cell in a Living Animal

The Janelia method that films nearly every cell of a living vertebrate at once, read through Frontier's evidence lens.

In 2013, a Janelia lab filmed more than 80% of the roughly 100,000 neurons in a larval zebrafish brain, and it was rightly called a landmark. Thirteen years later, the same campus has widened the lens from one organ to the entire animal. A method named WHOLISTIC records the activity of nearly every cell in a living vertebrate at the same time, from the neurons in its brain to the cells lining its gut, its kidney, its blood vessels, and its muscles, while the animal swims, eats, and sleeps.

The result was published in Nature on September 9, 2026 - Nature. It is not a drug, not a device you will buy, and not a headline most people saw. It is something quieter and, by Frontier's reading, more consequential: a new way of seeing that turns the whole body of an animal into a single, synchronized movie of cellular signaling. That is exactly the kind of result Frontier exists to surface, because its significance is easy to miss and hard to overstate.

This guide explains what WHOLISTIC actually is, how you build a microscope and a sensor that can watch an entire living animal, what the whole-body view revealed that a brain-only view could not, and why Frontier scores it a 70 out of 100. It also draws the line, honestly, between recording a phenomenon and understanding it, because the two are not the same thing, and the gap between them is where most of the work still lies.

Contents

1. The result, in one paragraph
2. The observability gap: why we only ever watched one organ
3. The microscopy, explained from first principles
4. Getting a sensor into every cell
5. The problem nobody advertises: motion
6. What the whole-body view revealed
7. WHOLISTIC versus prior whole-brain imaging
8. Frontier's read: evidence, impact, and novelty
9. The trade-offs, and the gap between recording and understanding
10. What comes next

1. The result, in one paragraph

WHOLISTIC stands for WHole Organism Live Imaging System for recording Tissue and IntraCellular activity, and the acronym is doing honest work: the point is to record intracellular activity across a whole organism at once. It was developed by Virginie Ruetten, a postdoctoral scientist in the lab of Janelia Senior Group Leader Misha Ahrens, working with collaborators at University College London, Virginia Tech, and Tsinghua University - EurekAlert. The system combines three things that had never been made to work together at this scale: a way to place a fluorescent activity sensor inside essentially every cell of a small transparent vertebrate, a microscope fast and gentle enough to image that entire body in three dimensions over hours, and a stack of computation that keeps track of each individual cell even as the animal's organs move.

The animal is the larval zebrafish, roughly one week old and small enough that its whole body fits within the working range of a microscope, yet complex enough to carry the same organ systems a human has: a brain and spinal cord, a heart and blood vessels, a gut, a liver, a pancreas, kidneys, gills, and skeletal muscle. By capturing the activity of all of these systems concurrently, the method reveals body-wide circuits, patterns of coordinated signaling that cross the boundaries between organs and that no single-organ recording could have seen. The work was first posted as a preprint in August 2025 and formally published a year later - bioRxiv. Frontier logs it as a 2026 breakthrough at a Frontier Score of 70, which places it at the top band of the year's index.

2. The observability gap: why we only ever watched one organ

To understand why this is a breakthrough rather than an increment, start with the structural problem, not the microscope. Biology has always been forced to choose its frame. You can study a molecule, or a cell, or a tissue, or an organ, or a whole animal, but historically you could not watch more than one of those levels at once with any real resolution. The tools were built around the boundaries of academic fields: neuroscientists imaged brains, cardiologists studied hearts, nephrologists studied kidneys, and each field developed instruments tuned to its own organ. The result is a map of the body assembled from separate photographs taken at different times under different conditions, then stitched together by inference.

That division is not how the body works. As Ahrens put it, evolution "didn't care whether a decision was implemented in the brain's prefrontal cortex or in a connection between the brainstem and the bladder" - phys.org. A living animal is a single integrated system in which the nervous system, the vasculature, the immune system, and the organs are in constant conversation, mostly through the same ancient signaling currency: calcium. Nearly every cell in the body raises and lowers its internal calcium concentration to signal, whether it is a neuron firing, a muscle contracting, or a cell responding to stress. If you could watch calcium everywhere at once, you would be watching the body talk to itself.

The reason nobody had done it is not that the idea is new. It is that the observability gap was a hard engineering wall. Ruetten framed the achievement precisely: "This work bridges two fundamental scales of biology, the cell and the organism, such that we can now fill that observability gap" - phys.org. The bridge matters because so much of physiology and medicine lives in the connections between organs rather than inside any one of them. A body-wide view is a precondition for asking, and answering, questions that field-by-field science was structurally unable to pose.

The lineage here runs directly through Janelia's own history. The Ahrens lab pioneered whole-brain calcium imaging in this same animal more than a decade ago, developing ways to outfit neurons with sensors that light up when calcium changes - Janelia. Ahrens has spent his career pushing the frontier of how much of a nervous system can be watched at once, and the whole-brain work is the reason larval zebrafish became a workhorse of systems neuroscience in the first place - Wikipedia. The field then spent years relaxing the constraints one at a time: a later advance recorded neurons at cellular resolution in a freely swimming fish rather than an immobilized one, chasing the goal of watching a brain during natural behavior - Nature Methods.

WHOLISTIC is the logical, and far harder, extension of that program: take the trick that worked for one organ and make it work for all of them at once. That is the sense in which this is a breakthrough of scope rather than of a single new physical principle, a distinction that matters a great deal when we get to Frontier's score. It is also why the achievement is best measured against the specific history of imaging in this animal, not against microscopy in general. Each prior step widened the frame a little; WHOLISTIC widened it to the edges of the body.

3. The microscopy, explained from first principles

To film cellular activity, you need two things: a way to make active cells emit light, and a way to collect that light in three dimensions fast enough to catch the activity as it happens. The first is chemistry and genetics, covered in the next section. The second is optics, and it is worth building up from the ground because the specific choice the team made runs against the reflex of the field.

Fluorescence is the starting point. A fluorescent molecule absorbs light at one color and re-emits it at another, slightly redder color a fraction of a moment later. If you engineer a molecule whose brightness depends on how much calcium is around it, then a cell that is signaling literally glows brighter than a cell that is quiet. Shine in blue light, collect the green glow, and you have turned an invisible chemical event into a measurable image. Do that fast enough and you have a movie. The catch is that a living body is not a clean sheet of glass. It is dense, layered tissue that scatters light in every direction, so photons coming back from a cell 100 micrometers deep are smeared and diluted by everything between that cell and the lens.

Here is where the interesting decision lives. The dominant tool for fast, gentle, whole-brain imaging in this animal has been light-sheet microscopy, which illuminates a single thin plane of the specimen from the side and images it from above, so that only the plane in focus is ever lit. Light-sheet is fast and causes little photodamage, and the Ahrens lab helped make it the standard for whole-brain work - Nature Methods. But a light sheet has to travel cleanly across the specimen to form a thin plane, and in the dense, pigmented, three-dimensional bulk of a whole body rather than the relatively clear brain, that sheet degrades. The team tested the options and reached a conclusion that surprises anyone steeped in the light-sheet era: for whole-body volumetric imaging, spinning-disk confocal microscopy was the most robust to tissue scattering and diffraction - preLights.

A confocal microscope rejects scattered light with a physical trick: it images through a pinhole that only lets through light originating from the exact plane in focus, discarding the blurred haze from above and below. A spinning-disk version puts thousands of pinholes on a rotating disk so the whole field is scanned in parallel many times a second, recovering much of the speed a single scanning pinhole would cost you. The practical geometry the team used tells you the scale: a field of view of roughly 800 by 600 micrometers, imaged in steps of about 9 micrometers through a depth of about 130 micrometers, using a 20x, 0.75 numerical-aperture objective - bioRxiv. The system trades the raw volumetric speed of the fastest brain-only methods for the one property whole-body imaging cannot do without: clean signal from deep, scattering tissue.

It is worth situating that choice in the wider effort to see deep into living systems, because scattering is the universal enemy of live imaging and different labs have attacked it differently. Some approaches fight it with adaptive optics that measure and cancel the distortion tissue imposes, an idea that has let other microscopes capture detailed three-dimensional movies of cells deep inside living organisms - Janelia. Others, like two-photon methods, use longer-wavelength light that penetrates tissue better. WHOLISTIC's answer is neither exotic optics nor a new laser: it is the older, unglamorous, and in this regime more reliable physics of confocal rejection, scaled up with a spinning disk to recover speed. The lesson is that the "best" microscope is entirely a function of the sample, and a whole body is a fundamentally different sample from a brain.

The whole pipeline, from labeled animal to a map of body-wide circuits, has five stages, and it is worth seeing them together before we take each apart.

That diagram is the argument of the paper in miniature. No single stage is unprecedented on its own. The achievement is that all five had to be solved together and made to hand off cleanly, because a failure at any one stage collapses the whole enterprise: a sensor that fades over hours, a microscope that cooks the animal, a motion-correction step that loses track of a cell, or a segmentation that cannot tell two neighbors apart would each be enough to make a body-wide recording unreadable.

4. Getting a sensor into every cell

The chemistry of the sensor is the second half of the imaging problem, and it is where the deepest genetic engineering went. The workhorse family of activity sensors is the genetically encoded calcium indicator, or GECI. The best known is GCaMP, a protein assembled from a jellyfish fluorescent protein fused to a calcium-binding domain. When calcium binds, the protein changes shape and its fluorescence jumps, so the brightness of a GCaMP-expressing cell tracks its calcium level in near real time. Because a GECI is a protein, an animal's own cells can be instructed to build it from a gene, which is what makes whole-body labeling even thinkable: you do not inject a dye into every cell, you write the sensor into the genome and let the animal manufacture it everywhere.

WHOLISTIC uses GCaMP7f, a fast green calcium indicator, as its primary sensor, with a red indicator, jRGECO1b, available for experiments that need a second color - bioRxiv. The hard part was not the sensor itself but getting it expressed uniformly in nearly every cell type and keeping that expression stable for the life of the experiment. Earlier attempts to drive a GECI from a ubiquitous promoter had failed in a telling way: expression was either confined to the first few cells of the embryo or was hopelessly sparse - WHOLISTIC resource. The team engineered transgenic zebrafish lines, built around a tTA/TRE amplification system, that drive sustained, high-fidelity sensor expression across more than 15 cell types at once - preLights. The tTA/TRE design is a two-part genetic amplifier: a broadly expressed driver protein binds a response element that in turn switches on the sensor gene, which is what lets a single genetic construct light up tissues as different as brain, kidney, and muscle without dropping out in half of them. Getting an animal to build a bright, non-toxic sensor uniformly in every tissue, and to keep building it for hours under a microscope, is a genetics problem at least as demanding as the optics.

Those lines are the quiet foundation of everything else, and the team has released them, along with data and protocols, as an open resource - WHOLISTIC resource. This matters more than it sounds. A whole-body activity map is only interpretable if you can trust that the label reaches the cells you care about, evenly, without silencing some tissues and saturating others. Uniform pancellular expression is the difference between a movie of the whole body and a movie of whichever cells happened to light up. The genetics, in other words, is not a preliminary step; it is a load-bearing part of the result, and it is the piece most likely to let other labs reproduce and extend the work.

There is one more genetic layer that makes the recordings interpretable. A calcium movie tells you which cells are active, but not what those cells are. To close that gap, the team paired live imaging with Whole-Body Expansion Microscopy, an enzyme-free protocol that physically swells a fixed specimen to about 5 times its size so that densely packed cells separate and can be identified - bioRxiv. It comes in two flavors that answer two questions: an immunofluorescence version reads protein markers to say what type a cell is, and an in situ hybridization version reads which genes a cell is transcribing. You film the living animal, then expand a matched specimen to read off, cell by cell, which glowing dot in the movie was a neuron, which was a chondrocyte, and which was a cell of the kidney tubule.

None of this works without solving the mundane but decisive problem of holding a small animal steady in the same orientation across different instruments, which is why the resource includes companion methods for mounting a larval zebrafish reproducibly across microscope configurations - PubMed. Mapping a live activity movie onto an expanded, stained anatomy only works if the two datasets can be registered to each other, and that registration begins with the physical geometry of how the fish was held. It is a reminder that a breakthrough at this scale is an assembly of dozens of unglamorous solved problems, any one of which, left unsolved, would break the chain.

5. The problem nobody advertises: motion

Here is the constraint that makes whole-body imaging genuinely different from whole-brain imaging, and it is the part most likely to be underappreciated by anyone who has not tried it. A brain, held still, is a nearly rigid object. A whole living body is not. The gut peristalses, the heart beats, blood vessels dilate and constrict, muscles contract, and the whole animal periodically tries to swim. Every one of those movements shifts the position of the very cells you are trying to track. A neuron in a clamped brain stays in roughly the same voxel for an hour. A cell in the viscera can slide, deform, and return, over and over, for the entire recording.

If you cannot follow a cell through that motion, you cannot measure its activity, because you no longer know which cell you are looking at from one frame to the next. This is why so much whole-body physiology has been done on anesthetized, paralyzed, or dead tissue: motion is easier to eliminate than to model. WHOLISTIC takes the harder path. It uses a custom, multi-scale iterative optical-flow algorithm that estimates the local motion fields throughout the body and warps each frame so that individual cells stay registered to one another, enabling stable tracking of single cells over hours even in the moving viscera - preLights. Optical flow is the same broad idea that lets a video codec follow a moving object between frames, applied here to non-rigid, three-dimensional biological tissue.

Once motion is corrected, the cells still have to be separated from one another and from the background, a step called segmentation. The team used Voluseg, a method built on constrained non-negative matrix factorization that decomposes the raw volumetric video into a set of individual cell signals - bioRxiv. Matrix factorization, in plain terms, assumes the messy recording is a sum of a manageable number of underlying sources (the cells) each with its own footprint and its own activity trace, and it solves for those sources. The output is what makes the whole thing scientifically usable: a time series of activity for each of a very large number of individual cells, spread across every tissue in the body.

It is worth pausing on the fact that the computation is not a convenience bolted onto the optics. It is co-equal with the microscope. The reason a body-wide movie was impossible before is as much that nobody could keep track of cells in a moving body as that nobody could image deep enough. This is the same structural lesson that shows up across modern data-heavy science, where the instrument and the algorithm that reads it are increasingly inseparable, a pattern we traced in our guide to AI reconstructing the structure of the Earth's core from seismic data. In both cases the raw signal is overwhelming and largely uninterpretable until computation turns it into something a human can reason about.

6. What the whole-body view revealed

A new instrument earns its keep by showing something the old ones could not. WHOLISTIC did, and the findings share a common shape: they are all about coordination across organs, exactly the kind of body-wide circuit that a single-organ recording is blind to by construction. None of these is a cure or a therapy. Each is a demonstration that the whole-body frame surfaces real biology, and together they are the evidence that the method is a discovery engine rather than a pretty picture.

The clearest example is the body's response to low oxygen. When the fish was made hypoxic, the team watched, in real time, a mesenteric artery constrict and blood flow to the gut fall to near-complete cessation, shunting the limited oxygen elsewhere - bioRxiv. Crucially, they could see the control signal for this redistribution originating in the brainstem, and they confirmed the causal link directly: optogenetically inhibiting the hindbrain instantly restored perfusion to the gut - preLights. That is a complete brain-to-organ circuit, observed and then tested, in a living animal. It is precisely the sort of connection that neuroscience and cardiovascular physiology, studied separately, could infer but never watch.

Several other findings extend the pattern into systems rarely imaged at cellular resolution in a behaving animal. During periods of motor quiescence, the fish's ependymal cells, which line the fluid-filled cavities of the brain and spinal cord, produced high-amplitude traveling calcium waves with a period of roughly 3 to 7 minutes, a rhythm the team connects to states resembling rest or sleep - bioRxiv. In the kidney, the nephron parcellated into 11 functional compartments and showed pulsating traveling waves of activity along its length. In the musculature, the team found a previously undescribed functional synergy between the cervical-epaxial muscles and the abdominal muscles, linked to their shared innervation.

Beyond those, the whole-body view produced a set of observations that read almost as a menu of what becomes visible when nothing is out of frame:

• Vagal-to-sphincter circuit - a direct, topographically organized pathway from motor vagal neurons to the gastropharyngeal sphincter.
• Ketamine and the meninges - the anesthetic stimulated cells of the meninges alongside neurons, a non-neuronal effect easy to miss in a brain-only recording.
• Cold-responsive chondrocytes - cartilage cells that responded to cold, identified from their activity signature - EurekAlert.

The through-line is that many of these phenomena are not hidden because they are small. They are hidden because they span organs, and the frame was always too narrow to contain both ends of the connection at once. Ahrens' summary is the honest version of the ambition: "There are no hidden parts anymore, in the end, and at that point, I think we have a chance for a real, full understanding" - phys.org. That is a claim about the frame, not yet a claim about understanding, and the distinction is the subject of section 9.

7. WHOLISTIC versus prior whole-brain imaging

WHOLISTIC did not arrive from nowhere, and the fairest way to judge it is against the specific lineage of functional imaging in this same animal. For more than a decade the frontier was defined by the brain, and progress there was measured largely in speed: how many complete volumes of the brain you could capture per second, because faster imaging catches faster neural events. Seeing that progression makes it obvious both how far the field has come and how deliberately WHOLISTIC steps off the speed axis.

Read left to right, the chart is a story about acceleration. The 2013 light-sheet method captured the whole brain at 0.8 volumes per second while resolving more than 80% of its roughly 100,000 neurons - Janelia. By 2017, extended-field light-field microscopy pushed whole-brain volumetric imaging to 77 volumes per second in a freely swimming fish, at the cost of spatial resolution that only held up when active neurons were sparse - eLife. By 2026, a remote-scanning light-sheet system imaging a voltage indicator reached 200.8 volumes per second, though it covered only about a quarter of the brain's neurons - Nature Methods. Each step bought speed, and each paid for it somewhere else.

WHOLISTIC is deliberately absent from that chart, and that is the point. It does not compete on volumes per second; its spinning-disk confocal recordings run on the order of seconds per volume and unfold over multi-hour sessions. What it changes is not the speed of the recording but the scope: instead of a fraction of one organ, it captures nearly every cell across more than fifteen cell types in nearly every tissue of the body. The field spent a decade optimizing the vertical axis, resolution and speed within the brain. WHOLISTIC rotates the question onto a new axis entirely, breadth across the whole organism, which is why comparing it on frame rate misses what it is for.

The table below sets the methods side by side on the dimensions that actually distinguish them. It is a comparison of capabilities, not a ranking, because these tools answer different questions and a single score would flatten that.

The comparison also clarifies why the microscope choice was not a step backward. Light-sheet and light-field are the right tools for imaging a mostly transparent brain as fast as possible. They are the wrong tools for imaging deep through the dense, scattering, moving bulk of a whole body over hours, which is the regime where spinning-disk confocal's scattering rejection wins. There is a longer history of engineering isotropic, whole-animal imaging at Janelia that WHOLISTIC builds on, including the Keller lab's work on whole-animal imaging with high spatio-temporal resolution - Janelia. WHOLISTIC's contribution is to marry that imaging ambition to a pancellular sensor and a motion-correction pipeline, and thereby to make the whole body, not just the whole brain, the unit of observation.

8. Frontier's read: evidence, impact, and novelty

Frontier scores every breakthrough on three measured pillars, Evidence, Impact, and Novelty, and traces each number back to a public record you can check yourself against the live index. WHOLISTIC lands at 70 out of 100, which is worth unpacking because a 70 is neither a shrug nor a coronation. It is what a genuinely novel, rigorously evidenced enabling method looks like when its largest consequences are still ahead of it. For context, the highest score anywhere in Frontier's 2026 index also sits at 70, as we laid out in our ranking of the latest scientific breakthroughs of 2026, so this result is at the ceiling of the year rather than the middle of the pack.

On evidence, WHOLISTIC scores high, and deservedly. The work is peer-reviewed in Nature, backed by an openly available preprint, and released with transgenic lines, data, and protocols so that others can reproduce it - WHOLISTIC resource. More importantly, the central biological claim is not merely observational. The hypoxia circuit was tested causally with optogenetics, and cell identities were validated anatomically with expansion microscopy. A method paper that both demonstrates a capability and uses it to make a falsifiable, tested claim is about as strong as evidence gets at this stage of a technology's life.

On novelty, the score is high but honestly bounded. Nothing in WHOLISTIC is a new law of physics. GECIs, confocal microscopy, optical flow, matrix factorization, and expansion microscopy all predate it. The novelty is in the integration and the scale: nobody had previously recorded cellular activity across nearly an entire vertebrate body, simultaneously, in a behaving animal, and the pancellular transgenic lines and motion pipeline that make it possible are themselves new. Frontier deliberately does not award maximum novelty to an integration of known parts, however impressive, and that ceiling is part of why the score is 70 rather than higher.

On impact, the pillar is where the honest tension sits, and it explains the rest of the number. The potential impact is field-creating: WHOLISTIC gives whole-organism physiology, a discipline that has largely been theoretical, an actual instrument. As Ahrens put it, the method lets "physiology, neuroscience, behavior, cell biology" connect - HHMI. But realized impact, as opposed to potential, is still small: this is a platform whose payoff depends on what the community discovers with it over the next several years, and on how far it generalizes beyond a one-week-old fish. Frontier scores what is demonstrated, not what is promised, which is why a result this significant is calibrated at 70 and flagged as under-covered: outside a handful of specialist outlets, a body-wide movie of a living vertebrate went almost unremarked, which is precisely the coverage gap Frontier is built to catch.

9. The trade-offs, and the gap between recording and understanding

No honest account of this work can stop at the highlights, and Frontier's rigor cuts both ways. The first and most fundamental caveat is the one the field has lived with for a century: the larval zebrafish is a model organism, not a human. It is chosen precisely because it is small, transparent, and genetically tractable, the qualities that make whole-body imaging possible at all, and those same qualities are what make it unlike a large, opaque, warm-blooded mammal. A body-wide circuit found in a fish is a hypothesis about mammals, not a fact about them, and the leap from one to the other has failed often enough in biology that it should never be assumed.

The second caveat is physical and unavoidable: phototoxicity. Every photon you use to image a living cell also deposits energy in it, and over a multi-hour recording that dose can perturb or damage the very biology you are trying to observe. This is the deep reason the field loved light-sheet in the first place, because illuminating only the plane in focus minimizes the dose. Spinning-disk confocal buys scattering rejection but is not free of this tension, and any whole-body result has to be read with the question of how much the light itself shaped what was seen. The team's multi-hour sessions are impressive precisely because keeping an animal healthy under continuous imaging is hard, but the ceiling is real and it bounds how long and how often you can watch.

The third caveat is the most important and the least discussed, and it applies to the entire genre of large-scale activity recording. Recording is not understanding. A movie of nearly every cell in a body produces a staggering volume of correlated time series, and correlation across organs is a starting point for a hypothesis, not a mechanism. Knowing that the brainstem and a gut artery are active together does not by itself tell you the wiring, the direction of causation, or the molecular signal in between. WHOLISTIC's own strongest result, the hypoxia circuit, earned its weight only because the team followed the correlation with a causal optogenetic test. The map is not the territory, and a body-wide activity map, for all its beauty, is still a map that has to be turned into causal, mechanistic knowledge one tested link at a time.

That gap is not a flaw in this work; it is the shape of the work ahead, and it is shared by every data-rich corner of modern biology. The same challenge, converting an overwhelming stream of measurements into validated mechanism, runs through modern biomedicine, from imaging to the computational design of therapeutics we examined in our explainer on AI-designed cancer vaccines. In each case the instrument or the algorithm has raced ahead of interpretation, and the scientific value is realized only when the flood of data is disciplined back into testable claims. WHOLISTIC's honesty about this, pairing observation with causal tests and anatomical validation, is part of why its evidence score is high, and it is the template for how the follow-on work should be judged.

10. What comes next

The near-term trajectory is legible from the paper itself. The team is already extending the approach to Danionella, a fish that stays transparent into adulthood, which would push whole-body imaging from a one-week-old larva toward a mature vertebrate and its full behavioral repertoire - phys.org. The pancellular transgenic strategy has already been ported, with a dedicated Danionella sensor line, which suggests the extension is engineering rather than invention - WHOLISTIC resource. If it works in an adult, the questions it can address widen sharply, from development and disease progression to the physiology of complex behavior, all observed body-wide.

The deeper bottleneck is not the microscope; it is the analysis. A body-wide, hours-long, cellular-resolution recording generates data at a scale that outstrips a human's ability to explore it by hand, and the field's honest constraint is now interpretive rather than optical. This is where computation, and increasingly machine learning, becomes decisive: motion correction and segmentation like the optical-flow and Voluseg steps here are only the first layer, and finding the meaningful body-wide circuits inside the correlations will demand analysis methods as carefully validated as the imaging. The instrument has moved the frontier; the tools that read it now have to catch up, and how quickly they do will determine how much of the promised impact is realized.

For a reader deciding how much weight to put on this, the framework is straightforward. Watch three things: whether the method generalizes beyond the larval zebrafish, whether the body-wide correlations it surfaces convert into causally tested circuits rather than accumulating as suggestive maps, and whether the open resource is actually adopted by labs outside Janelia. If those move in the right direction over the next few years, a 70 today will look conservative, because the impact pillar that is currently bounded by "demonstrated, not promised" will start to fill in. If they stall, WHOLISTIC will remain a beautiful and important instrument in search of the discoveries it was built to enable. Either way, it belongs on Frontier's index at the top band of the year, and it deserves far more attention than a body-wide movie of a living animal has so far received. The full evidence-scored picture, updated as the follow-on work lands, lives in the Frontier index.

This guide reflects the record as of September 20, 2026, drawing on the Nature paper published September 9, 2026 and its August 2025 preprint. Imaging specifications and biological findings are reported from the primary sources cited inline; where an exact figure (such as the precise volumetric acquisition rate of WHOLISTIC) was not stated in the sources available, it is described qualitatively rather than invented. Frontier Scores are recomputed as new evidence arrives, so verify the current number against the live index.