electron microscopy
Celebrating the Power of Connection This Holiday Season
Posted on by Lawrence Tabak, D.D.S., Ph.D.
Happy holidays to one and all! This short science video brings to mind all those twinkling lights now brightening the night, as we mark the beginning of winter and shortest day of the year. This video also helps to remind us about the power of connection this holiday season.
It shows a motor neuron in a mouse’s primary motor cortex. In this portion of the brain, which controls voluntary movement, heavily branched neural projections interconnect, sending and receiving signals to and from distant parts of the body. A single motor neuron can receive thousands of inputs at a time from other branching sensory cells, depicted in the video as an array of blinking lights. It’s only through these connections—through open communication and cooperation—that voluntary movements are possible to navigate and enjoy our world in all its wonder. One neuron, like one person, can’t do it all alone.
This power of connection, captured in this award-winning video from the 2022 Show Us Your Brains Photo and Video contest, comes from Forrest Collman, Allen Institute for Brain Science, Seattle. The contest is part of NIH’s Brain Research Through Advancing Innovative Neurotechnologies® (BRAIN) Initiative.
In the version above, we’ve taken some liberties with the original video to enhance the twinkling lights from the synaptic connections. But creating the original was quite a task. Collman sifted through reams of data from high-resolution electron microscopy imaging of the motor cortex to masterfully reconstruct this individual motor neuron and its connections.
Those data came from The Machine Intelligence from Cortical Networks (MICrONS) program, supported by the Intelligence Advanced Research Projects Activity (IARPA). It’s part of the Office of the Director of National Intelligence, one of NIH’s governmental collaborators in the BRAIN Initiative.
The MICrONS program aims to better understand the brain’s internal wiring. With this increased knowledge, researchers will develop more sophisticated machine learning algorithms for artificial intelligence applications, which will in turn advance fundamental basic science discoveries and the practice of life-saving medicine. For instance, these applications may help in the future to detect and evaluate a broad range of neural conditions, including those that affect the primary motor cortex.
Pretty cool stuff. So, as you spend this holiday season with friends and family, let this video and its twinkling lights remind you that there’s much more to the season than eating, drinking, and watching football games.
The holidays are very much about the power of connection for people of all faiths, beliefs, and traditions. It’s about taking time out from the everyday to join together to share memories of days gone by as we build new memories and stronger bonds of cooperation for the years to come. With this in mind, happy holidays to one and all.
Links:
“NIH BRAIN Initiative Unveils Detailed Atlas of the Mammalian Primary Motor Cortex,” NIH News Release, October 6, 2021
Forrest Collman (Allen Institute for Brain Science, Seattle)
Brain Research Through Advancing Innovative Neurotechnologies® (BRAIN) Initiative (NIH)
Show Us Your Brains Photo and Video Contest (BRAIN Initiative)
The Amazing Brain: Capturing Neurons in Action
Posted on by Lawrence Tabak, D.D.S., Ph.D.
With today’s powerful imaging tools, neuroscientists can monitor the firing and function of many distinct neurons in our brains, even while we move freely about. They also possess another set of tools to capture remarkable, high-resolution images of the brain’s many thousands of individual neurons, tracing the form of each intricate branch of their tree-like structures.
Most brain imaging approaches don’t capture neural form and function at once. Yet that’s precisely what you’re seeing in this knockout of a movie, another winner in the Show Us Your BRAINs! Photo and Video Contest, supported by NIH’s Brain Research through Advancing Innovative Neurotechnologies® (BRAIN) Initiative.
This first-of-its kind look into the mammalian brain produced by Andreas Tolias, Baylor College of Medicine, Houston, and colleagues features about 200 neurons in the visual cortex, which receives and processes visual information. First, you see a colorful, tightly packed network of neurons. Then, those neurons, which were colorized by the researchers in vibrant pinks, reds, blues, and greens, pull apart to reveal their finely detailed patterns and shapes. Throughout the video, you can see neural activity, which appears as flashes of white that resemble lightning bolts.
Making this movie was a multi-step process. First, the Tolias group presented laboratory mice with a series of visual cues, using a functional imaging approach called two-photon calcium imaging to record the electrical activity of individual neurons. While this technique allowed the researchers to pinpoint the precise locations and activity of each individual neuron in the visual cortex, they couldn’t zoom in to see their precise structures.
So, the Baylor team sent the mice to colleagues Nuno da Costa and Clay Reid, Allen Institute for Brain Science, Seattle, who had the needed electron microscopes and technical expertise to zoom in on these structures. Their data allowed collaborator Sebastian Seung’s team, Princeton University, Princeton, NJ, to trace individual neurons in the visual cortex along their circuitous paths. Finally, they used sophisticated machine learning algorithms to carefully align the two imaging datasets and produce this amazing movie.
This research was supported by Intelligence Advanced Research Projects Activity (IARPA), part of the Office of the Director of National Intelligence. The IARPA is one of NIH’s governmental collaborators in the BRAIN Initiative.
Tolias and team already are making use of their imaging data to learn more about the precise ways in which individual neurons and groups of neurons in the mouse visual cortex integrate visual inputs to produce a coherent view of the animals’ surroundings. They’ve also collected an even-larger data set, scaling their approach up to tens of thousands of neurons. Those data are now freely available to other neuroscientists to help advance their work. As researchers make use of these and similar data, this union of neural form and function will surely yield new high-resolution discoveries about the mammalian brain.
Links:
Tolias Lab (Baylor College of Medicine, Houston)
Nuno da Costa (Allen Institute for Brain Science, Seattle)
R. Clay Reid (Allen Institute)
H. Sebastian Seung (Princeton University, Princeton, NJ)
Machine Intelligence from Cortical Networks (MICrONS) Explorer
Brain Research through Advancing Innovative Neurotechnologies® (BRAIN) Initiative (NIH)
Show Us Your BRAINs Photo & Video Contest (BRAIN Initiative)
NIH Support: BRAIN Initiative; Common Fund
Mammalian Brain Like You’ve Never Seen It Before
Posted on by Dr. Francis Collins
Credit: Gao et. al, Science
Researchers are making amazing progress in developing new imaging approaches. And they are now using one of their latest creations, called ExLLSM, to provide us with jaw-dropping views of a wide range of biological systems, including the incredibly complex neural networks within the mammalian brain.
In this video, ExLLSM takes us on a super-resolution, 3D voyage through a tiny sample (0.0030 inches thick) from the part of the mouse brain that processes sensation, the primary somatosensory cortex. The video zooms in and out of densely packed pyramidal neurons (large yellow cell bodies), each of which has about 7,000 synapses, or connections. You can also see presynapses (cyan), the part of the neuron that sends chemical signals; and postsynapes (magenta), the part of the neuron that receives chemical signals.
At 1:45, the video zooms in on dendritic spines, which are mushroom-like nubs on the neuronal branches (yellow). These structures, located on the tips of dendrites, receive incoming signals that are turned into electrical impulses. While dendritic spines have been imaged in black and white with electron microscopy, they’ve never been presented before on such a vast, colorful scale.
The video comes from a paper, published recently in the journal Science [1], from the labs of Ed Boyden, Massachusetts Institute of Technology, Cambridge, and the Nobel Prize-winning Eric Betzig, Janelia Research Campus of the Howard Hughes Medical Institute, Ashburn, VA. Like many collaborations, this one comes with a little story.
Four years ago, the Boyden lab developed expansion microscopy (ExM). The technique involves infusing cells with a hydrogel, made from a chemical used in disposable diapers. The hydrogel expands molecules within the cell away from each other, usually by about 4.5 times, but still locks them into place for remarkable imaging clarity. It makes structures visible by light microscopy that are normally below the resolution limit.
Though the expansion technique has worked well with a small number of cells under a standard light microscope, it hasn’t been as successful—until now—at imaging thicker tissue samples. That’s because thicker tissue is harder to illuminate, and flooding the specimen with light often bleaches out the fluorescent markers that scientists use to label proteins. The signal just fades away.
For Boyden, that was a problem that needed to be solved. Because his lab’s goal is to trace the inner workings of the brain in unprecedented detail, Boyden wants to image entire neural circuits in relatively thick swaths of tissue, not just look at individual cells in isolation.
After some discussion, Boyden’s team concluded that the best solution might be to swap out the light source for the standard microscope with a relatively new imaging tool developed in the Betzig lab. It’s called lattice light-sheet microscopy (LLSM), and the tool generates extremely thin sheets of light that illuminate tissue only in a very tightly defined plane, dramatically reducing light-related bleaching of fluorescent markers in the tissue sample. This allows LLSM to extend its range of image acquisition and quickly deliver stunningly vivid pictures.
Telephone calls were made, and the Betzig lab soon welcomed Ruixuan Gao, Shoh Asano, and colleagues from the Boyden lab to try their hand at combining the two techniques. As the video above shows, ExLLSM has proved to be a perfect technological match. In addition to the movie above, the team has used ExLLSM to provide unprecedented views of a range of samples—from human kidney to neuron bundles in the brain of the fruit fly.
Not only is ExLLSM super-resolution, it’s also super-fast. In fact, the team imaged the entire fruit fly brain in 2 1/2 days—an effort that would take years using an electron microscope.
ExLLSM will likely never supplant the power of electron microscopy or standard fluorescent light microscopy. Still, this new combo imaging approach shows much promise as a complementary tool for biological exploration. The more innovative imaging approaches that researchers have in their toolbox, the better for our ongoing efforts to unlock the mysteries of the brain and other complex biological systems. And yes, those systems are all complex. This is life we’re talking about!
Reference:
[1] Cortical column and whole-brain imaging with molecular contrast and nanoscale resolution. Gao R, Asano SM, Upadhyayula S, Pisarev I, Milkie DE, Liu TL, Singh V, Graves A, Huynh GH, Zhao Y, Bogovic J, Colonell J, Ott CM, Zugates C, Tappan S, Rodriguez A, Mosaliganti KR, Sheu SH, Pasolli HA, Pang S, Xu CS, Megason SG, Hess H, Lippincott-Schwartz J, Hantman A, Rubin GM, Kirchhausen T, Saalfeld S, Aso Y, Boyden ES, Betzig E. Science. 2019 Jan 18;363(6424).
Links:
Video: Expansion Microscopy Explained (YouTube)
Video: Lattice Light-Sheet Microscopy (YouTube)
How to Rapidly Image Entire Brains at Nanoscale Resolution, Howard Hughes Medical Institute, January 17, 2019.
Synthetic Neurobiology Group (Massachusetts Institute of Technology, Cambridge)
Eric Betzig (Janelia Reseach Campus, Ashburn, VA)
NIH Support: National Institute of Neurological Disorders and Stroke; National Human Genome Research Institute; National Institute on Drug Abuse; National Institute of Mental Health; National Institute of Biomedical Imaging and Bioengineering
Snapshots of Life: An Elegant Design
Posted on by Dr. Francis Collins
Credit: David Sleboda and Thomas Roberts, Brown University, Providence, RI
Over the past few years, my blog has highlighted winners from the annual BioArt contest sponsored by the Federation of American Societies for Experimental Biology (FASEB). So, let’s keep a good thing going with one of the amazing scientific images that captured top honors in FASEB’s latest competition: a scanning electron micrograph of the hamstring muscle of a bullfrog.
That’s right, a bullfrog, For decades, researchers have used the American bullfrog, Rana catesbeiana, as a model for studying the physiology and biomechanics of skeletal muscles. My own early work with electron microscopy, as a student at Yale in the 1970s, was devoted to producing images from this very tissue. Thanks to its disproportionately large skeletal muscles, this common amphibian has played a critical role in helping to build the knowledge base for understanding how these muscles work in other organisms, including humans.
Revealed in this picture is the intricate matrix of connective tissue that holds together the frog’s hamstring muscle, with the muscle fibers themselves having been digested away with chemicals. And running diagonally, from lower left to upper right, you can see a band of fibrils made up of a key structural protein called collagen.
Merry Microscopy and a Happy New Technique!
Posted on by Dr. Francis Collins
Seasons Greetings! What looks like a humble wreath actually represents an awe-inspiring gift to biomedical research: a new imaging technique that adds a dash of color to the formerly black-and-white world of electron microscopy (EM). Here the technique is used to visualize the uptake of cell-penetrating peptides (red) by the fluid-filled vesicles (green) of the endosome (gray), a cellular compartment involved in molecular transport. Without the use of color to draw sharp contrasts between the various structures, such details would not be readily visible.
This innovative technique has its origins in a wonderful holiday story. In December 2003, Roger Tsien, a world-renowned researcher at the University of California, San Diego (UCSD), decided to give himself a special present. With the lab phones still and email traffic slow for the holidays, Tsien decided to take advantage of the peace and quiet to spend two weeks alone at the research bench, pursuing an intriguing, yet seemingly wacky, idea. He wanted to find a way to deposit ions of a rare earth metal, called lanthanum, directly into cells as the vital first step in creating a new imaging technique designed to infuse EM with some much-needed color. After the holidays, when the lab returned to its usual hustle and bustle, Tsien handed off his project to Stephen Adams, a research scientist in his lab, thereby setting in motion a nearly 13-year quest to perfect the colorful new mode of EM.
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