Scientists used to believe that the brain stopped making new brain cells past a certain age. But that believe changed in the late 1990’s as a result of several studies which were performed on mice at the Salk Institute.
After conducting maze tests, neuroscientist Fred H. Gage and his colleagues examined brain samples collected from mice. What they found challenged long standing believes held about neurogenesis, or the creation of new neurons.
To their astonishment, they discovered that the mice were creating new neurons. Their brains were regenerating themselves.
All of the mice showed evidence of neurogenesis but the brains of the athletic mice showed even more.
These mice, the ones that scampered on running wheels, were producing two to three times as many new neurons as the mice that didn’t exercise.
The difference between the mice who performed well on the maze tests and those that floundered was exercise.
That’s great for the mice, but what about humans?
To find out if neurogensis occurred in adult humans, Gage and his colleagues obtained brain tissue from deceased cancer patients who had donated their bodies to research. While still living, these people were injected with the same type of compound used on Gage’s mice to detect new neuron growth. When Gage dyed their brain samples, he saw new neurons. Like in the mice study, they found evidence of neurogenesis – the growth of new brain cells.
From the mice study, it appears that those who exercise produce even more new brain cells than those who don’t. Several studies on humans seem to suggest the same thing.
Studies performed at both the University of Illinois at Urbana- Champaign and Columbia University in New York City have shown that exercise benefits brain function. The test subjects were given aerobic exercises such as walking for at least one hour three times a week. After 6 months they showed significant improvements in memory as measured by a word-recall test. Using fMRI scans they also showed increases in blood flow to the hippocampus (part of the brain associated with memory and learning). Scientists suspect that the blood pumping into that part of the brain was helping to produce fresh neurons.
Dr. Patricia A. Boyle and her colleagues of Rush Alzheimer’s Disease Center in Chicago found that the greater a person’s muscle strength, the lower their likelihood of being diagnosed with Alzheimer’s. The same was true for the loss of mental function that often precedes full-blown Alzheimer’s.
Neuroscientist Gage, by the way, exercises just about every day, as do most colleagues in his field. As Scott Small a neurologist at Columbia explains,
I constantly get asked at cocktail parties what someone can do to protect their mental functioning. I tell them, ‘Put down that glass and go for a run.
So if you want to grow some new brain cells and improve your brain function, go get some exercise!
Source: How to Make New Brain Cells and Improve Brain Function | Online Brain Games Blog
- Using a drug already approved for clinical trials, researchers were able to reduce brain damage and boost the growth of new brain cells in mice suffering from strokes.
- The research offers new hope to those dealing with the aftermath of strokes, which are the fifth leading cause of death in the United States.
OLD DRUG, NEW TREATMENT
Researchers from the University of Manchester have developed a new treatment that could limit the damage caused by strokes and also promote repair in the affected area of the brain. What’s more, the drug they’re using has already been clinically approved.
The researchers’ study is published in Brain, Behavior and Immunity, and it recounts how they developed their treatment using mice bred to develop ischemic strokes, the most prevalent type of stroke and one that occurs when an artery that supplies oxygen-rich blood to the brain is blocked. Soon after the mice experienced a stroke, the researchers treated them with interleukin-1 receptor antagonist (IL-1Ra), an anti-inflammatory drug that is already licensed for use in treating rheumatoid arthritis.
They noticed a reduction in the amount of brain damage typically observed after a stroke and also noted that the drug boosted neurogenesis (the birth of new cells) in the areas that did experience brain damage in the days following the treatment. The mice even regained the motor skills they lost due to the stroke.
HOPE FOR A CURE
Stroke is the fifth leading cause of death in the United States and about 800,000 people suffer from one each year, according to the Centers for Disease Control and Prevention (CDC). They occur when the flow of blood to the brain is interrupted, usually due to a blood clot or a buildup of fat that broke off from the arteries and traveled to the brain. The condition is extremely dangerous because brain cells can die within a few minutes of the stroke, causing permanent damage or even death.
We still don’t have a treatment to adequately prevent or reverse the damage to the brain caused by strokes, but the Manchester researchers believe that their development could change that. Though they are still in early stages of clinical trials, they hope to eventually move on to larger trials and eventually human testing. Together with other research, this new study offers hope to the thousands of people whose lives are impacted by strokes worldwide.
Source: This FDA Approved Drug Could Permanently Repair Brain Damage in Stroke Victims
For over a decade, neuroscientists have been trying to figure out how neurogenesis (the birth of new neurons) and neuroplasticity (the malleability of neural circuits) work together to reshape how we think, remember, and behave.
This week, an eye-opening new study, “Adult-Born Neurons Modify Excitatory Synaptic Transmission to Existing Neurons” reported how newborn neurons (created via neurogenesis) weave themselves into a “new and improved” neural tapestry. The January 2017 findings were published in the journal eLife.
During this state-of-the-art study on mice, neuroscientists at the University of Alabama at Birmingham (UAB) found that the combination of neurogenesis and neuroplasticity caused less-fit older neurons to fade into oblivion and die off as the sprightly, young newborn neurons took over existing neural circuits by making more robust synaptic connections.
For their latest UAB study, Linda Overstreet-Wadiche and Jacques Wadiche—who are both associate professors in the University of Alabama at Birmingham Department of Neurobiology—focused on neurogenesis in the dentate gyrus region of the hippocampus.
The dentate gyrus is an epicenter of neurogenesis responsible for the formation of new episodic memories and the spontaneous exploration of novel environments, among other functions.
More specifically, the researchers focused on newly born granule cell neurons in the dentate gyrus that must become wired into a neural network by forming synapses via neuroplasticity in order to stay alive and participate in ongoing neural circuit function.
There are only two major brain regions that are currently believed to have the ability to continually give birth to new neurons via neurogenesis in adults; one is the hippocampus (long-term and spatial memory hub) the second is the cerebellum (coordination and muscle memory hub). Notably, granule cells have the highest rate of neurogenesis. Both the hippocampus and cerebellum are packed, chock-full with granule cells.
Interestingly, moderate to vigorous physical activity (MVPA) is one of the most effective ways to stimulate neurogenesis and the birth of new granule cells in the hippocampus and the cerebellum. (As a cornerstone of The Athlete’s Way platform, I’ve been writing about the link between MVPA and neurogenesis for over a decade. To read a wide range of Psychology Today blog posts on the topic click on this link.)
Drawing of Purkinje cells (A) and granule cells (B) from pigeon cerebellum by Santiago Ramón y Cajal, 1899. Source: Instituto Santiago Ramón y Cajal, Madrid, Spain
Granule cells were first identified by Santiago Ramón y Cajal, who made beautiful sketches in 1899 that illustrate how granule cells create synaptic connections with Purkinje cells in the cerebellum. His breathtaking and Nobel Prize-winning illustrations are currently on a museum tour across the United States (on loan from the Instituto Santiago Ramón y Cajal in Madrid, Spain) as part of “The Beautiful Brain” traveling art exhibit.
(As a side note, the olfactory bulb is the only other subcortical brain area known to have high rates of neurogenesis. Speculatively, this could be one reason that scent plays such an indelible and ever-changing role in our memory formation and ‘remembrance of things past.’)
Neurogenesis and Neuroplasticity Work Together to Rewire Neural Circuitry
One of the key aspects of neural plasticity is called Neural Darwinism, or “neural pruning,” which means that any neuron that isn’t ‘fired-and-wired’ together into a network is likely to be extinguished. The latest UAB research suggests that newborn neurons play a role in expediting this process by “winning out” in a survival of the fittest type of neuronal battle against their more elderly or worn out counterparts.
Long before there were neuroscientific studies on neuroplasticity and neurogenesis, Henry David Thoreau unwittingly described the process of how the paths that one’s mind travels can become hardwired (when you get stuck in a rut) by describing a well-worn path through the woods. In Walden, Thoreau writes,
“The surface of the earth is soft and impressible by the feet of men; and so with the paths which the mind travels. How worn and dusty, then, must be the highways of the world, how deep the ruts of tradition and conformity!”
From a psychological standpoint, the latest UAB discovery presents the exciting possibility that when adult-born neurons weave into existing neural networks that new memories are created and older memories may be modified.
Through neurogenesis and neuroplasticity, it may be possible to carve out a fresh and unworn path for your thoughts to travel upon. One could speculate that this process opens up the possibility to reinvent yourself and move away from the status quo or to overcome past traumatic events that evoke anxiety and stress. Hardwired fear-based memories often lead to avoidance behaviors that can hold you back from living your life to the fullest.
Future Research on Neurogenesis Could Lead to New PTSD Treatments
Granule cells in the dentate gyrus are part of a neural circuit that processes sensory and spatial input from other areas of the brain. By integrating sensory and spatial information, the dentate gyrus has the ability to generate unique and detailed memories of an experience.
Before this study, Overstreet-Wadiche and her UAB colleagues had a few basic questions about how the newly born granule cells in the dentate gyrus function. They asked themselves two specific questions:
- Since the number of neurons in the dentate gyrus increases by neurogenesis while the number of neurons in the cortex remains the same, does the brain create additional synapses from the cortical neurons to the new granule cells?
- Or do some cortical neurons transfer their connections from mature granule cells to the new granule cells?
Through a series of complex experiments with mice, Overstreet-Wadiche et al. found that some of the cortical neurons in the cerebral cortex transferred all of their former connections with older granule cells (that may have been worn out or past their prime) to the freshly born granule cells that were raring to go.
This revolutionary discovery opens the door to examine how the redistribution of synapses between old and new neurons helps the dentate gyrus stay up to date by forming new connections.
One of the key questions the researchers want to dive deeper into during upcoming experiments is: “How does this redistribution relate to the beneficial effects of exercise, which is a natural way to increase neurogenesis?”
In the future, it’s possible that cutting-edge research on neurogenesis and neuroplasticity could lead to finely-tuned neurobiological treatments for ailments such as post-traumatic stress disorder (PTSD) and dementia. In a statement to UAB, Overstreet-Wadiche said,
“Over the last 10 years there has been evidence supporting a redistribution of synapses between old and new neurons, possibly by a competitive process that the new cells tend to ‘win.’ Our findings are important because they directly demonstrate that, in order for new cells to win connections, the old cells lose connections.
So, the process of adult neurogenesis not only adds new cells to the network, it promotes plasticity of the existing network. It will be interesting to explore how neurogenesis-induced plasticity contributes to the function of this brain region.
Neurogenesis is typically associated with improved acquisition of new information, but some studies have also suggested that neurogenesis promotes ‘forgetting’ of existing memories.”
Aerobic Exercise Is the Most Effective Way to Stimulate Neurogenesis and Create Adult-Born Neurons
For the past 10 years, the actionable advice I’ve given in The Athlete’s Way has been rooted in the belief that through the daily process of working out anyone can stimulate neurogenesis and optimize his or her mindset and outlook on life via neuroplasticity.
“The Athlete’s Way” program is designed to reshape neural networks and optimize your mindset. Since the beginning, this program has been based on the discovery that aerobic activity produces brain-derived neurotrophic factor (BDNF) and stimulates the birth of new neurons through neurogenesis. I describe my philosophy in the Introduction to The Athlete’s Way,
“Shifting the focus from thinner thighs to stronger minds makes this exercise book unique. The Athlete’s Way does not focus just on sculpting six-pack abs or molding buns of steel. We are more interested in bulking up your neurons and reshaping your synapses to create an optimistic, resilient, and determined mindset. The goal is transformation from the inside out.
My mission is to get this message to you so that you can use neurobiology and behavioral models to help improve your life through exercise. I am a zealot about the power of sweat to transform people’s lives by transforming their minds. My conviction is strong and authentic because I have lived it.”
I created The Athlete’s Way along with the indispensable help of my late father, Richard Bergland, who was a visionary neuroscientist, neurosurgeon, and author of The Fabric of Mind (Viking).
A decade ago, when I published The Athlete’s Way: Sweat and the Biology of Bliss (St. Martin’s Press) I put neurogenesis and neuroplasticity in the spotlight. At the time, the discovery of neurogenesis was brand new, and still a radical notion in mainstream neuroscience.
In the early 21st century, most experts still believed that human beings were born with all the neurons they would have for their entire lifespan. If anything, it was believed that people could only lose neurons or “kill brain cells” as we got older.
Understandably, when I published The Athlete’s Way in 2007 there were lots of skeptics and naysayers who thought my ideas about reshaping mindset using a combination of neurogenesis and neuroplasticity through moderate to vigorous physical activity were ludicrous.
For the past 10 years, I’ve kept my antennae up and my finger on the pulse of all the latest research on neurogenesis and neuroplasticity hoping to find additional empirical evidence that gives more scientific credibility to my system of belief and The Athlete’s Way methodology.
Needless to say, I was over the moon and ecstatic this morning when I read about the new research by Linda Overstreet-Wadiche and Jacques Wadiche that pinpoints the specifics of how adult-born neurons modify existing neural circuits. This is fascinating stuff!
These are exciting times in neuroscience. Modern day neuroscientific techniques are poised to solve many more riddles regarding the complex mechanism by which neurogenesis and neuroplasticity work together as a dynamic duo to reshape our neural networks and functional connectivity between brain regions. Stay tuned for future empirical evidence and scientific research on neurogenesis and neuroplasticity in the months and years ahead.
In the meantime, if you’d like to read a free excerpt from The Athlete’s Way that provides some simple actionable advice and practical ways for you to stimulate neurogenesis and rewire your brain via neuroplasticity and moderate to vigorous physical activity—check out these pages from a section of my book titled: “Neuroplasticity and Neurogenesis: Combining Neuroscience and Sport.”
Elena W Adlaf, Ryan J Vaden, Anastasia J Niver, Allison F Manuel, Vincent C Onyilo, Matheus T Araujo, Cristina V Dieni, Hai T Vo, Gwendalyn D King, Jacques I Wadiche, Linda Overstreet-Wadiche. Adult-born neurons modify excitatory synaptic transmission to existing neurons. eLife, 2017; 6 DOI: 10.7554/eLife.19886
Source: How Do Neuroplasticity and Neurogenesis Rewire Your Brain? | Psychology Today
Neural stem cells (NSCs) give rise to neurons during development. NSCs persist and neurogenesis continues in restricted regions of postnatal and adult brains. Adult-born neurons integrate into existing neural circuits by synaptic connections and participate in the regulation of brain function. Thus, understanding NSCs and neurogenesis may be crucial in the development of new strategies for brain repair. Here, we introduce the lineage of NSCs from embryonic to adult stages and summarize recent studies on maturation and integration of adult-born neurons. We also discuss the regulation and potential functions of adult neurogenesis in physiological and pathological conditions.
Get access to the full text of this article
Source: The role of neurogenesis during development and in the adult brain – Jin – 2016 – European Journal of Neuroscience – Wiley Online Library
FEBRUARY 3, 2017
Summary: Researchers report adult neurogenesis not only helps increase the number of cells in a neural network, it also promotes plasticity in the existing network. Additionally, they have identified the role the Bax gene plays in synaptic pruning.
Source: University of Alabama at Birmingham.
One goal in neurobiology is to understand how the flow of electrical signals through brain circuits gives rise to perception, action, thought, learning and memories.
Linda Overstreet-Wadiche, Ph.D., and Jacques Wadiche, Ph.D., both associate professors in the University of Alabama at Birmingham Department of Neurobiology, have published their latest contribution in this effort, focused on a part of the brain that helps form memories — the dentate gyrus of the hippocampus.
The dentate gyrus is one of just two areas in the brain where new neurons are continuously formed in adults. When a new granule cell neuron is made in the dentate gyrus, it needs to get ‘wired in,’ by forming synapses, or connections, in order to contribute to circuit function. Dentate granule cells are part of a circuit that receive electrical signals from the entorhinal cortex, a cortical brain region that processes sensory and spatial input from other areas of the brain. By combining this sensory and spatial information, the dentate gyrus can generate a unique memory of an experience.
Overstreet-Wadiche and UAB colleagues posed a basic question: Since the number of neurons in the dentate gyrus increases by neurogenesis while the number of neurons in the cortex remains the same, does the brain create additional synapses from the cortical neurons to the new granule cells, or do some cortical neurons transfer their connections from mature granule cells to the new granule cells?
Their answer, garnered through a series of electrophysiology, dendritic spine density and immunohistochemistry experiments with mice that were genetically altered to produce either more new neurons or kill off newborn neurons, supports the second model — some of the cortical neurons transfer their connections from mature granule cells to the new granule cells.
This opens the door to look at how this redistribution of synapses between the old and new neurons helps the dentate gyrus function. And it opens up tantalizing questions. Does this redistribution disrupt existing memories? How does this redistribution relate to the beneficial effects of exercise, which is a natural way to increase neurogenesis?
“Over the last 10 years there has been evidence supporting a redistribution of synapses between old and new neurons, possibly by a competitive process that the new cells tend to ‘win,’” Overstreet-Wadiche said. “Our findings are important because they directly demonstrate that, in order for new cells to win connections, the old cells lose connections. So, the process of adult neurogenesis not only adds new cells to the network, it promotes plasticity of the existing network.”
The study opens the door to look at how this redistribution of synapses between the old and new neurons helps the dentate gyrus function. NeuroscienceNews.com image is for illustrative purposes only.
“It will be interesting to explore how neurogenesis-induced plasticity contributes to the function of this brain region,” she continued. “Neurogenesis is typically associated with improved acquisition of new information, but some studies have also suggested that neurogenesis promotes ‘forgetting’ of existing memories.”
The researchers also unexpectedly found that the Bax gene, known for its role in apoptosis, appears to also play a role in synaptic pruning in the dentate gyrus.
“There is mounting evidence that the cellular machinery that controls cell death also controls the strength and number of synaptic connections,” Overstreet-Wadiche said. “The appropriate balance of synapses strengthening and weakening, collectively termed synaptic plasticity, is critical for appropriate brain function. Hence, understanding how synaptic pruning occurs may shed light on neurodevelopmental disorders and on neurodegenerative diseases in which a synaptic pruning gone awry may contribute to pathological synapse loss.”
ABOUT THIS NEUROSCIENCE RESEARCH ARTICLE
All of the work was performed in the Department of Neurobiology at UAB. In addition to Overstreet-Wadiche and Wadiche, co-authors of the paper, “Adult born neurons modify excitatory synaptic transmission to existing neurons,” published in eLife, are Elena W. Adlaf, Ryan J. Vaden, Anastasia J. Niver, Allison F. Manuel, Vincent C. Onyilo, Matheus T. Araujo, Cristina V. Dieni, Hai T. Vo and Gwendalyn D. King.
Much of the data came from the doctoral thesis research of Adlaf, a former UAB Neuroscience graduate student who is now a postdoctoral fellow at Duke University.
Funding: Funding for this research came from Civitan International Emerging Scholars awards, and National Institutes of Health awards or grants NS098553, NS064025, NS065920 and NS047466.
Source: Jeff Hansen – University of Alabama at Birmingham
Image Source: NeuroscienceNews.com image is in the public domain.
Original Research: Full open access research for “Adult-born neurons modify excitatory synaptic transmission to existing neurons” by Elena W Adlaf, Ryan J Vaden, Anastasia J Niver, Allison F Manuel, Vincent C Onyilo, Matheus T Araujo, Cristina V Dieni, Hai T Vo, Gwendalyn D King, Jacques I Wadiche, and Linda Overstreet-Wadiche in eLife. Published online January 30 2017 doi:10.7554/eLife.19886
Did You Know How Loud Balloons Can Be?
Adult-born neurons are continually produced in the dentate gyrus but it is unclear whether synaptic integration of new neurons affects the pre-existing circuit. Here we investigated how manipulating neurogenesis in adult mice alters excitatory synaptic transmission to mature dentate neurons. Enhancing neurogenesis by conditional deletion of the pro-apoptotic gene Bax in stem cells reduced excitatory postsynaptic currents (EPSCs) and spine density in mature neurons, whereas genetic ablation of neurogenesis increased EPSCs in mature neurons. Unexpectedly, we found that Bax deletion in developing and mature dentate neurons increased EPSCs and prevented neurogenesis-induced synaptic suppression. Together these results show that neurogenesis modifies synaptic transmission to mature neurons in a manner consistent with a redistribution of pre-existing synapses to newly integrating neurons and that a non-apoptotic function of the Bax signaling pathway contributes to ongoing synaptic refinement within the dentate circuit.
“Adult-born neurons modify excitatory synaptic transmission to existing neurons” by Elena W Adlaf, Ryan J Vaden, Anastasia J Niver, Allison F Manuel, Vincent C Onyilo, Matheus T Araujo, Cristina V Dieni, Hai T Vo, Gwendalyn D King, Jacques I Wadiche, and Linda Overstreet-Wadiche in eLife. Published online January 30 2017 doi:10.7554/eLife.19886
Source: Brain Plasticity: How Adult Born Neurons Get Wired – Neuroscience News