Snapshots of Life: The Brain’s Microscopic Green Trash Bins

Zebrafish brain

Credit: Marina Venero Galanternik, Daniel Castranova, Tuyet Nguyen, and Brant M. Weinstein, NICHD, NIH

There are trash bins in our homes, on our streets, and even as a popular icon on our desktop computers. And as this colorful image shows, trash bins of the cellular variety are also important in the brain.

This image—a winner in the Federation of American Societies for Experimental Biology’s 2017 BioArt competition—shows the brain of an adult zebrafish, a popular organism for studying how the brain works. It captures dense networks of blood vessels (red) lining the outer surface of the brain. Next to many of these vessels sit previously little-studied cells called fluorescent granular perithelial cells (yellowish green). Researchers now believe these cells, often shortened to FGPs, act much like trash receptacles that continuously take in and store waste products to keep the brain tidy and functioning well.

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Snapshots of Life: The Birth of New Neurons

Radial Glia in Oil

Credit: Kira Mosher, University of California, Berkeley

After a challenging day at work or school, sometimes it may seem like you are down to your last brain cell. But have no fear—in actuality, the brains of humans and other mammals have the potential to produce new neurons throughout life. This remarkable ability is due to a specific type of cell—adult neural stem cells—so beautifully highlighted in this award-winning micrograph.

Here you see the nuclei (purple) and arm-like extensions (green) of neural stem cells, along with nuclei of other cells (blue), in brain tissue from a mature mouse. The sample was taken from the subgranular zone of the hippocampus, a region of the brain associated with learning and memory. This zone is also one of the few areas in the adult brain where stem cells are known to reside.

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Unraveling the Biocircuitry of Obesity

Mouse neurons

Caption: Mouse neurons (purple), with their nuclei (blue) and primary cilia (green).
Credit: Yi Wang, Vaisse Lab, UCSF

Obesity involves the complex interplay of diet, lifestyle, genetics, and even the bacteria living in the gut. But there are other less-appreciated factors that are likely involved, and a new NIH-supported study suggests one that you probably never would have imagined: antenna-like sensory projections on brain cells.

The study in mice, published in the journal Nature Genetics [1], suggests these neuronal projections, called primary cilia, are a key part of a known “hunger circuit,” which receives signals from other parts of the body to control appetite. The researchers add important evidence in mouse studies showing that changes in the primary cilia can produce a short circuit, impairing the brain’s ability to regulate appetite and leading to overeating and obesity.

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Snapshots of Life: Growing Mini-Brains in a Dish

Brain grown in a lab dish

Credit: Collin Edington and Iris Lee, Department of Biomedical Engineering, MIT

Something pretty incredible happens—both visually and scientifically—when researchers spread neural stem cells onto a gel-like matrix in a lab dish and wait to see what happens. Gradually, the cells differentiate and self-assemble to form cohesive organoids that resemble miniature brains!

In this image of a mini-brain organoid, the center consists of a clump of neuronal bodies (magenta), surrounded by an intricate network of branching extensions (green) through which these cells relay information. Scattered throughout the mini-brain are star-shaped astrocytes (red) that serve as support cells.

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Creative Minds: Seeing Memories in a New Light

Steve Ramirez

Steve Ramirez/Joshua Sariñana

Whether it’s lacing up for a morning run, eating blueberry scones, or cheering on the New England Patriots, Steve Ramirez loves life and just about everything in it. As an undergraduate at Boston University, this joie de vivre actually made Ramirez anxious about choosing just one major. A serendipitous conversation helped him realize that all of the amazing man-made stuff in our world has a common source: the human brain.

So, Ramirez decided to pursue neuroscience and began exploring the nature of memory. Employing optogenetics (using light to control brain cells) in mice, he tagged specific neurons that housed fear-inducing memories, making the neurons light sensitive and amenable to being switched on at will.

In groundbreaking studies that earned him a spot in Forbes 2015 “30 Under 30” list, Ramirez showed that it’s possible to reactivate memories experimentally in a new context, recasting them in either a more negative or positive behavior-changing light [1–3]. Now, with support from a 2016 NIH Director’s Early Independence Award, Ramirez, who runs his own lab at Boston University, will explore whether activating good memories holds promise for alleviating chronic stress and psychiatric disease.

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