How Sleep Resets the Brain

dendrites

Caption: Colorized 3D reconstruction of dendrites. Neurons receive input from other neurons through synapses, most of which are located along the dendrites on tiny projections called spines.
Credit: The Center for Sleep and Consciousness, University of Wisconsin-Madison School of Medicine

People spend about a third of their lives asleep. When we get too little shut-eye, it takes a toll on attention, learning and memory, not to mention our physical health. Virtually all animals with complex brains seem to have this same need for sleep. But exactly what is it about sleep that’s so essential?

Two NIH-funded studies in mice now offer a possible answer. The two research teams used entirely different approaches to reach the same conclusion: the brain’s neural connections grow stronger during waking hours, but scale back during snooze time. This sleep-related phenomenon apparently keeps neural circuits from overloading, ensuring that mice (and, quite likely humans) awaken with brains that are refreshed and ready to tackle new challenges.

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Creative Minds: The Worm Tissue-ome Teaches Developmental Biology for Us All

C. elegans

Caption: An adult Caenorhabditis elegans, 5 days
Credit: Coleen Murphy, Princeton University, Princeton, NJ

In the nearly 40 years since Nobel Prize-winning scientist Sydney Brenner proposed using a tiny, transparent soil worm called Caenorhabditis elegans as a model organism for biomedical research, C. elegans has become one of the most-studied organisms on the planet. Researchers have determined that C. elegans has exactly 959 cells, 302 of which are neurons. They have sequenced and annotated its genome, developed an impressive array of tools to study its DNA, and characterized the development of many of its tissues.

But what researchers still don’t know is exactly how all of these parts work together to coordinate this little worm’s response to changes in nutrition, environment, health status, and even the aging process. To learn more, 2015 NIH Director’s Pioneer Award winner Coleen Murphy of Princeton University, Princeton, NJ, has set out to analyze which genes are active, or transcribed, in each of the major tissues of adult C. elegans, building the framework for what’s been dubbed the C. elegans “tissue-ome.”

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LabTV: Curious About a Mother’s Bond

Bianca JonesThe bond between a mother and her child is obviously very special. That’s true not only in humans, but in mice and other animals that feed and care for their young. But what exactly goes on in the brain of a mother when she hears her baby crying? That’s one of the fascinating questions being explored by Bianca Jones Marlin, the young neuroscience researcher featured in this LabTV video.

Currently a postdoctoral fellow at New York University School of Medicine, Marlin is particularly interested in the influence of a hormone called oxytocin, popularly referred to as the “love hormone,” on maternal behaviors. While working on her Ph.D.in the lab of Robert Froemke, Marlin tested the behavior and underlying brain responses of female mice—both mothers and non-mothers—upon hearing distress cries of young mice, which are called pups. She also examined how those interactions changed with the addition of oxytocin.

I’m pleased to report that the results of the NIH-funded work Marlin describes in her video appeared recently in the highly competitive journal Nature [1]. And what she found might strike a chord with all the mothers out there. Her studies show that oxytocin makes key portions of the mouse brain more sensitive to the cries of the pups, almost as if someone turned up the volume.

In fact, when Marlin and her colleagues delivered oxytocin to the brains (specifically, the left auditory cortexes) of mice with no pups of their own, they responded like mothers themselves! Those childless mice quickly learned to perk up and fetch pups in distress, returning them to the safety of their nests.

Marlin says her interest in neuroscience arose from her experiences growing up in a foster family. She witnessed some of her foster brothers and sisters struggling with school and learning. As an undergraduate at Saint John’s University in Queens, NY, she earned a dual bachelor’s degree in Biology and Adolescent Education before getting her license to teach 6th through 12th grade Biology. But Marlin soon decided she could have a greater impact by studying how the brain works and gaining a better understanding of the biological mechanisms involved in learning, whether in the classroom or through life experiences, such as motherhood.

Marlin welcomes the opportunity that the lab gives her to “be an explorer”—to ask deep, even ethereal, questions and devise experiments aimed at answering them. “That’s the beauty of science and research,” she says. “To be able to do that the rest of my life? I’d be very happy.”

References:

[1] Oxytocin enables maternal behaviour by balancing cortical inhibition. Marlin BJ, Mitre M, D’amour JA, Chao MV, Froemke RC. Nature. 2015 Apr 23;520(7548):499-504.

Links:

LabTV

Froemke Lab (NYU Langone)

Science Careers (National Institute of General Medical Sciences/NIH)

Careers Blog (Office of Intramural Training/NIH)

Scientific Careers at NIH

 

Neuroscience: The Power of Curiosity to Inspire Learning

Snowflakes activating the brainWhen our curiosity is piqued, learning can be a snap and recalling the new information comes effortlessly. But when it comes to things we don’t care about—the recipe to that “delicious” holiday fruitcake or, if we’re not really into football, the results of this year’s San Diego County Credit Union Poinsettia Bowl—the new information rarely sticks.

To probe why this might be so, neuroscientists Charan Ranganath and Matthias Gruber, and psychologist Bernard Gelman, all at the University of California at Davis, devised a multi-step experiment to explore which regions of the brain are activated when we are curious, and how curiosity enhances our ability to learn and remember.

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Can Something in Young Blood Give a Boost to Old Brains?

Fountain of youth with bloodInfusing blood from younger creatures into older ones in hopes of halting—or even reversing—the aging process may sound like a macabre scene straight out of “Game of Thrones.” However, several scientific studies have shown that when older animals receive blood from younger counterparts, it improves the function of stem cells throughout the body, boosting tissue regeneration and healing. What’s not been clear is whether this activity can also rejuvenate the brain’s cognitive powers.

Let’s face it: aging is tough on the brain. The number of neural stem cells shrinks, producing fewer neurons; and many of the genes that promote brain development and neural connections become less active. To find out if young blood might hold some of the answers to this complex problem, two teams of NIH-funded researchers—one in Massachusetts and the other in California—recently turned to mice as a model system.

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