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First Comprehensive Census of Cell Types in Brain Area Controlling Movement

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Credit: SciePro/Shutterstock; BRAIN Initiative Cell Census Network, Nature, 2021

The primary motor cortex is the part of the brain that enables most of our skilled movements, whether it’s walking, texting on our phones, strumming a guitar, or even spiking a volleyball. The region remains a major research focus, and that’s why NIH’s Brain Research Through Advancing Innovative Neurotechnologies® (BRAIN) Initiative – Cell Census Network (BICCN) has just unveiled two groundbreaking resources: a complete census of cell types present in the mammalian primary motor cortex, along with the first detailed atlas of the region, located along the back of the frontal lobe in humans (purple stripe above).

This remarkably comprehensive work, detailed in a flagship paper and more than a dozen associated articles published in the journal Nature, promises to vastly expand our understanding of the primary motor cortex and how it works to keep us moving [1]. The papers also represent the collaborative efforts of more than 250 BICCN scientists from around the world, teaming up over many years.

Started in 2013, the BRAIN Initiative is an ambitious project with a range of groundbreaking goals, including the creation of an open-access reference atlas that catalogues all of the brain’s many billions of cells. The primary motor cortex was one of the best places to get started on assembling an atlas because it is known to be well conserved across mammalian species, from mouse to human. There’s also a rich body of work to aid understanding of more precise cell-type information.

Taking advantage of recent technological advances in single-cell analysis, the researchers categorized into different types the millions of neurons and other cells in this brain region. They did so on the basis of morphology, or shape, of the cells, as well as their locations and connections to other cells. The researchers went even further to characterize and sort cells based on: their complex patterns of gene expression, the presence or absence of chemical (or epigenetic) marks on their DNA, the way their chromosomes are packaged into chromatin, and their electrical properties.

The new data and analyses offer compelling evidence that neural cells do indeed fall into distinct types, with a high degree of correspondence across their molecular genetic, anatomical, and physiological features. These findings support the notion that neural cells can be classified into molecularly defined types that are also highly conserved or shared across mammalian species.

So, how many cell types are there? While that’s an obvious question, it doesn’t have an easy answer. The number varies depending upon the method used for sorting them. The researchers report that they have identified about 25 classes of cells, including 16 different neuronal classes and nine non-neuronal classes, each composed of multiple subtypes of cells.

These 25 classes were determined by their genetic profiles, their locations, and other characteristics. They also showed up consistently across species and using different experimental approaches, suggesting that they have important roles in the neural circuitry and function of the motor cortex in mammals.

Still, many precise features of the cells don’t fall neatly into these categories. In fact, by focusing on gene expression within single cells of the motor cortex, the researchers identified more potentially important cell subtypes, which fall into roughly 100 different clusters, or distinct groups. As scientists continue to examine this brain region and others using the latest new methods and approaches, it’s likely that the precise number of recognized cell types will continue to grow and evolve a bit.

This resource will now serve as a springboard for future research into the structure and function of the brain, both within and across species. The datasets already have been organized and made publicly available for scientists around the world.

The atlas also now provides a foundation for more in-depth study of cell types in other parts of the mammalian brain. The BICCN is already engaged in an effort to generate a brain-wide cell atlas in the mouse, and is working to expand coverage in the atlas for other parts of the human brain.

The cell census and atlas of the primary motor cortex are important scientific advances with major implications for medicine. Strokes commonly affect this region of the brain, leading to partial or complete paralysis of the opposite side of the body.

By considering how well cell census information aligns across species, scientists also can make more informed choices about the best models to use for deepening our understanding of brain disorders. Ultimately, these efforts and others underway will help to enable precise targeting of specific cell types and to treat a wide range of brain disorders that affect thinking, memory, mood, and movement.


[1] A multimodal cell census and atlas of the mammalian primary motor cortex. BRAIN Initiative Cell Census Network (BICCN). Nature. Oct 6, 2021.


NIH Brain Research Through Advancing Innovative Neurotechnologies® (BRAIN) Initiative (NIH)

BRAIN Initiative – Cell Census Network (BICCN) (NIH)

NIH Support: National Institute of Mental Health; National Institute of Neurological Disorders and Stroke

NIH’s Nobel Winners Demonstrate Value of Basic Research

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Credit: Niklas Elmehed © Nobel Prize Outreach

Last week was a big one for both NIH and me. Not only did I announce my plans to step down as NIH Director by year’s end to return to my lab full-time, I was reminded by the announcement of the 2021 Nobel Prizes of what an honor it is to be affiliated an institution with such a strong, sustained commitment to supporting basic science.

This year, NIH’s Nobel excitement started in the early morning hours of October 4, when two NIH-supported neuroscientists in California received word from Sweden that they had won the Nobel Prize in Physiology or Medicine. One “wake up” call went to David Julius, University of California, San Francisco (UCSF), who was recognized for his groundbreaking discovery of the first protein receptor that controls thermosensation, the body’s perception of temperature. The other went to his long-time collaborator, Ardem Patapoutian, Scripps Research Institute, La Jolla, CA, for his seminal work that identified the first protein receptor that controls our sense of touch.

But the good news didn’t stop there. On October 6, the 2021 Nobel Prize in Chemistry was awarded to NIH-funded chemist David W.C. MacMillan of Princeton University, N.J., who shared the honor with Benjamin List of Germany’s Max Planck Institute. (List also received NIH support early in his career.)
The two researchers were recognized for developing an ingenious tool that enables the cost-efficient construction of “greener” molecules with broad applications across science and industry—including for drug design and development.

Then, to turn this into a true 2021 Nobel Prize “hat trick” for NIH, we learned on October 12 that two of this year’s three Nobel winners in Economic Sciences had been funded by NIH. David Card, an NIH-supported researcher at University of California, Berkley, was recognized “for his empirical contributions to labor economics.” He shared the 2021 prize with NIH grantee Joshua Angrist of Massachusetts Institute of Technology, Cambridge, and his colleague Guido Imbens of Stanford University, Palo Alto, CA, “for their methodological contributions to the analysis of causal relationships.” What a year!

The achievements of these and NIH’s 163 past Nobel Prize winners stand as a testament to the importance of our agency’s long and robust history of investing in basic biomedical research. In this area of research, scientists ask fundamental questions about how life works. The answers they uncover help us to understand the principles, mechanisms, and processes that underlie living organisms, including the human body in sickness and health.

What’s more, each advance builds upon past discoveries, often in unexpected ways and sometimes taking years or even decades before they can be translated into practical results. Recent examples of life-saving breakthroughs that have been built upon years of fundamental biomedical research include the mRNA vaccines for COVID-19 and the immunotherapy approaches now helping people with many types of cancer.

Take the case of the latest Nobels. Fundamental questions about how the human body responds to medicinal plants were the initial inspiration behind the work of UCSF’s Julius. He’d noticed that studies from Hungary found that a natural chemical in chili peppers, called capsaicin, activated a subgroup of neurons to create the painful, burning sensation that most of us have encountered from having a bit too much hot sauce. But what wasn’t known was the molecular mechanism by which capsaicin triggered that sensation.

In 1997, having settled on the best experimental approach to study this question, Julius and colleagues screened millions of DNA fragments corresponding to genes expressed in the sensory neurons that were known to interact with capsaicin. In a matter of weeks, they had pinpointed the gene encoding the protein receptor through which capsaicin interacts with those neurons [1]. Julius and team then determined in follow-up studies that the receptor, later named TRPV1, also acts as a thermal sensor on certain neurons in the peripheral nervous system. When capsaicin raises the temperature to a painful range, the receptor opens a pore-like ion channel in the neuron that then transmit a signal for the unpleasant sensation on to the brain.

In collaboration with Patapoutian, Julius then turned his attention from hot to cold. The two used the chilling sensation of the active chemical in mint, menthol, to identify a protein called TRPM8, the first receptor that senses cold [2, 3]. Additional pore-like channels related to TRPV1 and TRPM8 were identified and found to be activated by a range of different temperatures.

Taken together, these breakthrough discoveries have opened the door for researchers around the world to study in greater detail how our nervous system detects the often-painful stimuli of hot and cold. Such information may well prove valuable in the ongoing quest to develop new, non-addictive treatments for pain. The NIH is actively pursuing some of those avenues through its Helping to End Addiction Long-termSM (HEAL) Initiative.

Meanwhile, Patapoutian was busy cracking the molecular basis of another basic sense: touch. First, Patapoutian and his collaborators identified a mouse cell line that produced a measurable electric signal when individual cells were poked. They had a hunch that the electrical signal was generated by a protein receptor that was activated by physical pressure, but they still had to identify the receptor and the gene that coded for it. The team screened 71 candidate genes with no luck. Then, on their 72nd try, they identified a touch receptor-coding gene, which they named Piezo1, after the Greek word for pressure [4].

Patapoutian’s group has since found other Piezo receptors. As often happens in basic research, their findings have taken them in directions they never imagined. For example, they have discovered that Piezo receptors are involved in controlling blood pressure and sensing whether the bladder is full. Fascinatingly, these receptors also seem to play a role in controlling iron levels in red blood cells, as well as controlling the actions of certain white blood cells, called macrophages.

Turning now to the 2021 Nobel in Chemistry, the basic research of MacMillan and List has paved the way for addressing a major unmet need in science and industry: the need for less expensive and more environmentally friendly catalysts. And just what is a catalyst? To build the synthetic molecules used in drugs and a wide range of other materials, chemists rely on catalysts, which are substances that control and accelerate chemical reactions without becoming part of the final product.

It was long thought there were only two major categories of catalysts for organic synthesis: metals and enzymes. But enzymes are large, complex proteins that are hard to scale to industrial processes. And metal catalysts have the potential to be toxic to workers, as well as harmful to the environment. Then, about 20 years ago, List and MacMillan, working independently from each other, created a third type of catalyst. This approach, known as asymmetric organocatalysis [5, 6], builds upon small organic molecule catalysts that have a stable framework of carbon atoms, to which more active chemical groups can attach, often including oxygen, nitrogen, sulfur, or phosphorus.

Organocatalysts have gone on to be applied in ways that have proven to be more cost effective and environmentally friendly than using traditional metal or enzyme catalysts. In fact, this precise new tool for molecular construction is now being used to build everything from new pharmaceuticals to light-absorbing molecules used in solar cells.

That brings us to the Nobel Prize in the Economic Sciences. This year’s laureates showed that it’s possible to reach cause-and-effect answers to questions in the social sciences. The key is to evaluate situations in groups of people being treated differently, much like the design of clinical trials in medicine. Using this “natural experiment” approach in the early 1990s, David Card produced novel economic analyses, showing an increase in the minimum wage does not necessarily lead to fewer jobs. In the mid-1990s, Angrist and Imbens then refined the methodology of this approach, showing that precise conclusions can be drawn from natural experiments that establish cause and effect.

Last year, NIH added the names of three scientists to its illustrious roster of Nobel laureates. This year, five more names have been added. Many more will undoubtedly be added in the years and decades ahead. As I’ve said many times over the past 12 years, it’s an extraordinary time to be a biomedical researcher. As I prepare to step down as the Director of this amazing institution, I can assure you that NIH’s future has never been brighter.


[1] The capsaicin receptor: a heat-activated ion channel in the pain pathway. Caterina MJ, Schumacher MA, Tominaga M, Rosen TA, Levine JD, Julius D. Nature 1997:389:816-824.

[2] Identification of a cold receptor reveals a general role for TRP channels in thermosensation. McKemy DD, Neuhausser WM, Julius D. Nature 2002:416:52-58.

[3] A TRP channel that senses cold stimuli and menthol. Peier AM, Moqrich A, Hergarden AC, Reeve AJ, Andersson DA, Story GM, Earley TJ, Dragoni I, McIntyre P, Bevan S, Patapoutian A. Cell 2002:108:705-715.

[4] Piezo1 and Piezo2 are essential components of distinct mechanically activated cation channels. Coste B, Mathur J, Schmidt M, Earley TJ, Ranade S, Petrus MJ, Dubin AE, Patapoutian A. Science 2010:330: 55-60.

[5] Proline-catalyzed direct asymmetric aldol reactions. List B, Lerner RA, Barbas CF. J. Am. Chem. Soc. 122, 2395–2396 (2000).

[6] New strategies for organic catalysis: the first highly enantioselective organocatalytic Diels-AlderReaction. Ahrendt KA, Borths JC, MacMillan DW. J. Am. Chem. Soc. 2000, 122, 4243-4244.


Basic Research – Digital Media Kit (NIH)

Curiosity Creates Cures: The Value and Impact of Basic Research (National Institute of General Medical Sciences/NIH)

Explaining How Research Works (NIH)

NIH Basics, Collins FS, Science, 3 Aug 2012. 337; 6094: 503.

NIH’s Commitment to Basic Science, Mike Lauer, Open Mike Blog, March 25, 2016

Nobel Laureates (NIH)

The Nobel Prize in Physiology or Medicine 2021 (The Nobel Assembly at the Karolinska Institutet, Stockholm, Sweden)

Video: Announcement of the 2021 Nobel Prize in Physiology or Medicine (YouTube)

The Nobel Prize in Chemistry 2021 (The Nobel Assembly at the Karolinska Institutet)

Video: Announcement of the 2021 Nobel Prize in Chemistry (YouTube)

The Nobel Prize in Economic Sciences (The Nobel Assembly at the Karolinska Institutet)

Video: Announcement of the 2021 Nobel Prize in Economic Sciences (YouTube)

Julius Lab (University of California San Francisco)

The Patapoutian Lab (Scripps Research, La Jolla, CA)

Benjamin List (Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany)

The MacMillan Group (Princeton University, NJ)

David Card (University of California, Berkeley)

Joshua Angrist (Massachusetts Institute of Technology, Cambridge)

NIH Support:

David Julius: National Institute of Neurological Diseases and Stroke; National Institute of General Medical Sciences; National Institute of Dental and Craniofacial Research

Ardem Patapoutian: National Institute of Neurological Diseases and Stroke; National Institute of Dental and Craniofacial Research; National Heart, Lung, and Blood Institute

David W.C. MacMillan: National Institute of General Medical Sciences

David Card: National Institute on Aging; Eunice Kennedy Shriver National Institute of Child Health and Human Development

Joshua Angrist: Eunice Kennedy Shriver National Institute of Child Health and Human Development

Learning to Protect Communities with COVID-19 Home Testing Programs

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Credit: Say Yes! COVID Test

With most kids now back in school, parents face a new everyday concern: determining whether their child’s latest cough or sneeze might be a sign of COVID-19. If so, parents will want to keep their child at home to protect other students and staff, while also preventing the spread of the virus in their communities. And if it’s the parent who has a new cough, they also will want to know if the reason is COVID-19 before going to work or the store.

Home tests are now coming online to help concerned people make the right choice quickly. As more COVID-19 home tests enter the U.S. marketplace, research continues to help optimize their use. That’s why NIH and the Centers for Disease Control and Prevention (CDC) are teaming up in several parts of the country to provide residents age 2 and older with free home-testing kits for COVID-19. These reliable, nasal swab tests provide yes-or-no answers in about 15 minutes for parents and anyone else concerned about their possible exposure to the novel coronavirus.

The tests are part of an initiative called Say Yes! COVID Test (SYCT) that’s evaluating how best to implement home-testing programs within range of American communities, both urban and rural. The lessons learned are providing needed science-based data to help guide public health officials who are interested in implementing similar home-testing programs in communities throughout their states.

After successful eight-week pilot programs this past spring and summer in parts of North Carolina, Tennessee, and Michigan, SYCT is partnering this fall with four new communities. They are Fulton County, GA; Honolulu County, HI; and Louisville Metro, KY; with another community in the Midwest to be announced later this month.

The Georgia and Hawaii partnerships, launched on September 20, are already off to a flying start. In Fulton County, home to Atlanta and several small cities, 21,673 direct-to-consumer orders (173,384 tests) have already been received. In Honolulu County, demand for the tests has exceeded all expectations, with 91,000 orders received in the first week (728,000 tests). The online ordering has now closed in Hawaii, and the remaining tests will be distributed on the ground through the local public health department.

SYCT offers the Quidel QuickVue® At-Home COVID-19 test, which is supplied through the NIH Rapid Acceleration of Diagnostics (RADx) initiative. The antigen test uses a self-collected nasal swab sample that is placed in a test tube containing solution, followed by a test strip. Colored lines that appear on the test strip indicate a positive or negative result—similar to a pregnancy test.

The program allows residents in participating counties to order free home tests online or for in-person pick up at designated sites in their community. Each resident can ask for eight rapid tests, which equals two weekly tests over four weeks. An easy-to-navigate website like this one and a digital app, developed by initiative partner CareEvolution, are available for residents to order their tests, sign-up for testing reminders, and allow voluntary test result reporting to the public health department.

SYCT will generate data to answer several important questions about self or home-testing. They include questions about consumer demand, ensuring full community access, testing behavior, willingness to report test results, and, above all, effectiveness in controlling the spread of SARS-CoV-2, the coronavirus that causes COVID-19

Researchers at the University of North Carolina-Chapel Hill; Duke University, Durham, NC; and the UMass Chan Medical School, Worcester, MA, will help crunch the data and look for guiding themes. They will also conduct a study pre- and post-intervention to evaluate levels of SARS-CoV-2 in the community, including using measures of virus in wastewater. In addition, researchers will compare their results to other counties similar in size and infection rates, but that are not participating in a free testing initiative.

The NIH and CDC are exploring ways to scale a SYCT-like program nationally to communities experiencing surges in COVID-19. The Biden Administration also recently invoked the Defense Production Act to purchase millions of COVID-19 home tests to help accelerate their availability and offer them at a lower cost to more Americans. That encompasses many different types of people, including concerned parents who need a quick-and-accurate answer on whether their children’s cough or sneeze is COVID-19.


COVID-19 Research (NIH)

Say Yes! COVID Test

Rapid Acceleration of Diagnostics (RADx) (NIH)

NIH Support: National Institute of Biomedical Imaging and Bioengineering; National Heart, Lung, and Blood Institute; National Institute on Minority Health and Health Disparities

Most Vaccine-Hesitant People Remain Willing to Change Their Minds

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A young black woman looks thoughful. A graph show changes in willingness to recieve the vaccine
Credit: fizkes/Shutterstock; adapted from Siegler, JAMA Netw Open. 2021

As long and difficult as this pandemic has been, I remain overwhelmingly grateful for the remarkable progress being made, including the hard work of so many people to develop rapidly and then deploy multiple life-saving vaccines. And yet, grave concerns remain that vaccine hesitancy—the reluctance of certain individuals and groups to get themselves and their children vaccinated—could cause this pandemic to go on much longer than it should.

We’re seeing the results of such hesitancy in the news every day, highlighting the rampant spread of COVID-19 that’s stretching our healthcare systems and resources dangerously thin in many places. The vast majority of those currently hospitalized with COVID-19 are unvaccinated, and most of those tragic 2,000 deaths each day could have been prevented. The stories of children and adults who realized too late the importance of getting vaccinated are heartbreaking.

With these troubling realities in mind, I was encouraged to see a new study in the journal JAMA Network Open that tracked vaccine hesitancy over time in a random sample of more than 4,600 Americans. This national study shows that vaccine hesitancy isn’t set in stone. Over the course of this pandemic, hesitancy has decreased, and many who initially said no are now getting their shots. Many others who remain unvaccinated lean toward making an appointment.

The findings come from Aaron Siegler and colleagues, Emory University, Atlanta. They were interested in studying how entrenched vaccine hesitancy would be over time. The researchers also wanted to see how often those who were initially hesitant went on to get their shots.

To find out, they recruited a diverse, random, national sampling of individuals from August to December 2020, just before the first vaccines were granted Emergency Use Approval and became widely available. They wanted to get a baseline, or starting characterization, on vaccine hesitancy. Participants were asked two straightforward questions, “Have you received the COVID-19 vaccine?” and “How likely are you to get it in the future?” From March to April 2021, the researchers followed up by asking participants the same questions again when vaccines were more readily available to many (although still not all) adults.

The survey’s initial results showed that nearly 70 percent of respondents were willing to get vaccinated at the outset, with the other 30 percent expressing some hesitancy. The good news is among the nearly 3,500 individuals who answered the survey at follow-up, about a third who were initially vaccine hesitant already had received at least one shot. Another third also said that they’d now be willing to get the vaccine, even though they hadn’t just yet.

Among those who initially expressed a willingness to get vaccinated, about half had done so at follow up by spring 2021 (again, some still may not have been eligible). Forty percent said they were likely to get vaccinated. However, 7 percent of those who were initially willing said they were now less likely to get vaccinated than before.

There were some notable demographic differences. Folks over age 65, people who identified as non-Hispanic Asians, and those with graduate degrees were most likely to have changed their minds and rolled up their sleeves. Only about 15 percent in any one of these groups said they weren’t willing to be vaccinated. Most reluctant older people ultimately got their shots.

The picture was more static for people aged 45 to 54 and for those with a high school education or less. The majority of those remained unvaccinated, and about 40 percent still said they were unlikely to change their minds.

At the outset, people of Hispanic heritage were as willing as non-Hispanic whites to get vaccinated. At follow-up, however, fewer Hispanics than non-Hispanic whites said they’d gotten their shots. This finding suggests that, in addition to some hesitancy, there may be significant barriers still to overcome to make vaccination easier and more accessible to certain groups, including Hispanic communities from Central and South America.

Willingness among non-Hispanic Blacks was consistently lowest, but nearly half had gotten at least one dose of vaccine by the time they completed the second survey. That’s comparable to the vaccination rate in white study participants. For more recent data on vaccination rates by race/ethnicity, see this report from the Kaiser Family Foundation.

Overall, while a small number of respondents grew more reluctant over time, most people grew more comfortable with the vaccines and were more likely to say they’d get vaccinated, if they hadn’t already. In fact, by the end of the study, the hesitant group had shrunk from 31 to 15 percent. It’s worth noting that the researchers checked the validity of self-reported vaccination using antibody tests and the results matched up rather well.

This is all mostly good news, but there’s clearly more work to do. An estimated 70 million eligible Americans have yet to get their first shot, and remain highly vulnerable to infection and serious illness from the Delta variant. They are capable of spreading the virus to other vulnerable people around them (including children), and incubating the next variants that might provide more resistance to the vaccines and therapies. They are also at risk for Long COVID, even after a relatively mild acute illness.

The work ahead involves answering questions and addressing concerns from people who remain hesitant. It’s also incredibly important to reach out to those willing, but unvaccinated, individuals, to see what can be done to help them get their shots. If you happen to be one of those, it’s easy to find the places near you that have free vaccines ready to administer. Go to, or punch 438829 on your cell phone and enter your zip code—in less than a minute you will get the location of vaccine sites nearby.

Nearly 400 million COVID-19 vaccine doses have been administered in communities all across the United States. More than 600,000 more are being administered on average each day. And yet, more than 80,000 new infections are still reported daily, and COVID-19 still steals the lives of about 2,000 mostly unvaccinated people each day.

These vaccines are key for protecting yourself and ultimately beating this pandemic. As these findings show, the vast majority of Americans understand this and either have been vaccinated or are willing to do so. Let’s keep up the good work, and see to it that even more minds will be changed—and more individuals protected before they may find it’s too late.


[1] Trajectory of COVID-19 vaccine hesitancy over time and association of initial vaccine hesitancy with subsequent vaccination. Siegler AJ, Luisi N, Hall EW, Bradley H, Sanchez T, Lopman BA, Sullivan PS. JAMA Netw Open. 2021 Sep 1;4(9):e2126882.


COVID-19 Research (NIH)

COVID-19 Vaccinations in the United States (Centers for Disease Control and Prevention, Atlanta)

Aaron Siegler (Emory University, Atlanta)

NIH Support: National Institute for Allergy and Infectious Diseases

New Microscope Technique Provides Real-Time 3D Views

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Most of the “cool” videos shared on my blog are borne of countless hours behind a microscope. Researchers must move a biological sample through a microscope’s focus, slowly acquiring hundreds of high-res 2D snapshots, one painstaking snap at a time. Afterwards, sophisticated computer software takes this ordered “stack” of images, calculates how the object would look from different perspectives, and later displays them as 3D views of life that can be streamed as short videos.

But this video is different. It was created by what’s called a multi-angle projection imaging system. This new optical device requires just a few camera snapshots and two mirrors to image a biological sample from multiple angles at once. Because the device eliminates the time-consuming process of acquiring individual image slices, it’s up to 100 times faster than current technologies and doesn’t require computer software to construct the movie. The kicker is that the video can be displayed in real time, which isn’t possible with existing image-stacking methods.

The video here shows two human melanoma cells, rotating several times between overhead and side views. You can see large amounts of the protein PI3K (brighter orange hues indicate higher concentrations), which helps some cancer cells divide and move around. Near the cell’s perimeter are small, dynamic surface protrusions. PI3K in these “blebs” is thought to help tumor cells navigate and survive in foreign tissues as the tumor spreads to other organs, a process known as metastasis.

The new multi-angle projection imaging system optical device was described in a paper published recently in the journal Nature Methods [1]. It was created by Reto Fiolka and Kevin Dean at the University of Texas Southwestern Medical Center, Dallas.

Like most technology, this device is complicated. Rather than the microscope and camera doing all the work, as is customary, two mirrors within the microscope play a starring role. During a camera exposure, these mirrors rotate ever so slightly and warp the acquired image in such a way that successive, unique perspectives of the sample magically come into view. By changing the amount of warp, the sample appears to rotate in real-time. As such, each view shown in the video requires only one camera snapshot, instead of acquiring hundreds of slices in a conventional scheme.

The concept traces to computer science and an algorithm called the shear warp transform method. It’s used to observe 3D objects from different perspectives on a 2D computer monitor. Fiolka, Dean, and team found they could implement a similar algorithm optically for use with a microscope. What’s more, their multi-angle projection imaging system is easy-to-use, inexpensive, and can be converted for use on any camera-based microscope.

The researchers have used the device to view samples spanning a range of sizes: from mitochondria and other tiny organelles inside cells to the beating heart of a young zebrafish. And, as the video shows, it has been applied to study cancer and other human diseases.

In a neat, but also scientifically valuable twist, the new optical method can generate a virtual reality view of a sample. Any microscope user wearing the appropriately colored 3D glasses immediately sees the objects.

While virtual reality viewing of cellular life might sound like a gimmick, Fiolka and Dean believe that it will help researchers use their current microscopes to see any sample in 3D—offering the chance to find rare and potentially important biological events much faster than is possible with even the most advanced microscopes today.

Fiolka, Dean, and team are still just getting started. Because the method analyzes tissue very quickly within a single image frame, they say it will enable scientists to observe the fastest events in biology, such as the movement of calcium throughout a neuron—or even a whole bundle of neurons at once. For neuroscientists trying to understand the brain, that’s a movie they will really want to see.


[1] Real-time multi-angle projection imaging of biological dynamics. Chang BJ, Manton JD, Sapoznik E, Pohlkamp T, Terrones TS, Welf ES, Murali VS, Roudot P, Hake K, Whitehead L, York AG, Dean KM, Fiolka R. Nat Methods. 2021 Jul;18(7):829-834.


Metastatic Cancer: When Cancer Spreads (National Cancer Institute)

Fiolka Lab (University of Texas Southwestern Medical Center, Dallas)

Dean Lab (University of Texas Southwestern)

Microscopy Innovation Lab (University of Texas Southwestern)

NIH Support: National Cancer Institute; National Institute of General Medical Sciences

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