Posts Tagged rewire
The brain’s complex network of neurons enables us to interpret and effortlessly navigate and interact with the world around us. But when these links are damaged due to injury or stroke, critical tasks like perception and movement can be disrupted. New research is helping scientists figure out how to harness the brain’s plasticity to rewire these lost connections, an advance that could accelerate the development of neuro-prosthetics.
A new study authored by Marc Schieber, M.D., Ph.D., and Kevin Mazurek, Ph.D. with the University of Rochester Medical Center Department of Neurology and the Del Monte Institute for Neuroscience, which appears in the journal Neuron, shows that very low levels of electrical stimulation delivered directly to an area of the brain responsible for motor function can instruct an appropriate response or action, essentially replacing the signals we would normally receive from the parts of the brain that process what we hear, see, and feel.
“The analogy is what happens when we approach a red light,” said Schieber. “The light itself does not cause us to step on the brake, rather our brain has been trained to process this visual cue and send signals to another parts of the brain that control movement. In this study, what we describe is akin to replacing the red light with an electrical stimulation which the brain has learned to associate with the need to take an action that stops the car.”
The findings could have significant implications for the development of brain-computer interfaces and neuro-prosthetics, which would allow a person to control a prosthetic device by tapping into the electrical activity of their brain.
To be effective, these technologies must not only receive output from the brain but also deliver input. For example, can a mechanical arm tell the user that the object they are holding is hot or cold? However, delivering this information to the part of the brain responsible for processing sensory inputs does not work if this part of the brain is injured or the connections between it and the motor cortex are lost. In these instances, some form of input needs to be generated that replaces the signals that combine sensory perception with motor control and the brain needs to “learn” what these new signals mean.
“Researchers have been interested primarily in stimulating the primary sensory cortices to input information into the brain,” said Schieber. “What we have shown in this study is that you don’t have to be in a sensory-receiving area in order for the subject to have an experience they can identify.”
A similar approach is employed with cochlear implants for hearing loss which translate sounds into electrical stimulation of the inner ear and, over time, the brain learns to interpret these inputs as sound.
In the new study, the researchers detail a set of experiments in which monkeys were trained to perform a task when presented with a visual cue, either turning, pushing, or pulling specific objects when prompted by different lights. While this occurred, the animals simultaneously received a very mild electrical stimulus called a micro-stimulation in different areas of the premotor cortex — the part of the brain that initiates movement — depending upon the task and light combination.
The researchers then replicated the experiments, but this time omitted the visual cue of the lights and instead only delivered the micro-stimulation. The animals were able to successfully identify and perform the tasks they had learned to associate with the different electrical inputs. When the pairing of micro-stimulation with a particular action was reshuffled, the animals were able to adjust, indicating that the association between stimulation and a specific movement was learned and not fixed.
“Most work on the development of inputs to the brain for use with brain-computer interfaces has focused primarily on the sensory areas of the brain,” said Mazurek. “In this study, we show you can expand the neural real estate that can be targeted for therapies. This could be very important for people who have lost function in areas of their brain due to stroke, injury, or other diseases. We can potentially bypass the damaged part of the brain where connections have been lost and deliver information to an intact part of the brain.”
[Infographic] This nifty infographic is a great introduction to neuroplasticity and cognitive therapy
It’s startling to think about how we’ve got a spaceship billions of miles away rendezvousing with Pluto, yet here on Earth there are major aspects of our own anatomy that we’re almost completely ignorant about. We’ve climbed Everest, sent men to the moon, and invented the Internet — but we still don’t know how our brains work. The positive outlook is that many health, science, and research specialists believe we’re on the precipice of some major neuroscientific breakthroughs.
One example of a recent discovery with major implications is our further understanding of neuroplasticity. Simply put, we used to think our brain was what it was — unchangeable, unalterable. We were stuck with what nature gave us. In actuality, our brains are like plastic. We can alter neurochemistry to change beliefs, thoughts processes, emotions, etc. You are the architect of your brain. You also have the power to act against dangerous impulses such as addiction. The therapeutic possibilities here are endless.
Below, broken up into two parts, is a terrific infographic detailing the essence of what we know about neuroplasticity and how it works. It was created by the folks at Alta Mira, a San Francisco-area rehabilitation and recovery center.
Want a high-res, unedited version of the image above? Your wish is my command.
You can ask many different experts, and neuroplasticity will be explained in many different ways. The purpose of this website is not to get into technical jargon that overwhelms the stroke patient but rather to educate persons about stroke rehabilitation in simple laymen terms. In stroke recovery, neuroplasticity basically refers to the ability of the brain to rewire or reorganize itself after injury. Various studies over the past decade have shown that the adult brain can “rewire” itself when damaged. Studies have also shown that the adult brain can create new neurons, a phenomenon called neurogenesis. These new neurons require support from neighboring cells, blood supply, and connection with other neurons to survive. Certain requirements must be met during rehabilitation for neurogenesis and plasticity to actually change the brain. Rehabilitation involving neuroplasticity principles requires repetition of task and task specific practice to be effective. What this means for the stroke patient is that going to see your therapist for a one hour visit (or even a 3 hour visit) is not enough to lead to neuroplastic changes in the brain. Patients need to think of physical, occupational, and speech therapy as an adjunct to stroke recovery. It’s up to the patient to make the most of recovery by continuously using the injured parts of the body and mind outside of therapy sessions in everyday life.
A good comparison would be how one learns multiplication. A teacher doesn’t just show a multiplication table a couple of times to her students for the concept to be mastered. Instead, students have to practice over and over to learn and master multiplication. A child doesn’t learn how to walk overnight. It requires much practice. A baseball player doesn’t become elite just by playing a few games of baseball. You must take control of your stroke recovery process and be willing to invest a lot of time and energy if you want to see change especially with moderate to severe stroke. It’s also important to keep using a skill once you have mastered it – use it or lose it as you often hear in rehab.
Please note that plasticity doesn’t mean that one can practice every task over and over and accomplish them all. Stroke is much more complicated than that. Different parts of the brain control different body functions and the brain adapts better to some areas of damage more than others. Scientists have identified certain areas of the brain that yield neurogenesis but have not identified it in all areas of the brain. If you want to learn more about your specific stroke, ask your neurologist specifically what areas of your brain were affected. The neurologist will also be able to tell you what problems you can expect because of that damage (e.g. speech deficits, vision deficits, dizziness, difficulties with balance, etc.) You can further improve your rehabilitation by specifically targeting the weaknesses caused by your stroke.
In my opinion, neuroplasticity doesn’t necessarily change exercise and therapeutic activities done in stroke rehabilitation but rather emphasizes that more repetition and task specific practice is needed. Probably the most commonly used therapy that is based on neuroplasticity is constraint induced therapy. Constraint induced therapy involves limiting the movement of the non-affected or stronger arm and instead using the affected or weaker arm more frequently and intensely. There has been some positive research results with constraint induced therapy, however, it requires much effort and patience from the stroke patient. Some other treatments that may help with brain reorganization include interactive metronome, brain retraining software and websites, mirror box therapy, and robotic and gait devices that assist with movement repetition.
Research is still needed in the area of brain plasticity and stroke rehabilitation. Scientists have demonstrated that brain reorganization can occur, but only limited rehab treatments have been developed that address neuroplasticity. The stroke patient, however, armed with the knowledge that brain rewiring occurs with repetition, can improve their rehabilitation outcomes by application of this concept in their daily lives. Remember, therapy is an adjunct to recovery. You cannot go to therapy sessions and expect positive outcomes without applying what you have learned on a consistent daily basis.
Temporary sensory deprivation may improve recovery following a stroke by making space for the brain to rewire itself, suggests new research by the Washington University School of Medicine in St. Louis, MO.
The team revealed that mice were more likely to recover use of a front paw after a stroke if they had their whiskers trimmed.
A rodent’s whiskers are an important sensory organ with a rich nerve supply.
The animal can move its whiskers forwards and backwards to explore stationary objects and can keep them still to explore moving objects, all the while sending sensory information to the brain.
The researchers suggest that clipping a mouse’s whiskers stops the brain from receiving sensory signals, leaving the affected area more “plastic” and able to rewire itself to perform other tasks.
Implications for stroke rehabilitation
A stroke occurs when either a clot or rupture in a blood vessel in the brain blocks the blood supply and stops the affected area from receiving the oxygen and nutrients that it needs to keep cells alive and working.
When the affected area of the brain stops receiving the blood that it needs, brain cells die and the corresponding part of the body stops working properly or fails to work at all.
Often, the approach to rehabilitation therapy that individuals receive following a stroke focuses on helping them to compensate for the disability. The researchers propose that their study points to an alternative approach.
“Our findings,” says senior study author Jin-Moo Lee, a professor of neurology, “suggest that we may be able to stimulate [stroke] recovery by temporarily vacating some brain real estate and making that region of the brain more plastic.”
“One way to do that might be by immobilizing a healthy limb,” he adds.
Every year, around 140,000 people die from stroke in the United States, where it accounts for 1 out of every 20 deaths. The estimated cost of stroke — including medical care, drugs, and missed work days — is around $34 billion per year.
Brain remaps functions to nearby areas
There are more than 6.5 million stroke survivors in the U.S. Thanks to the brain’s plasticity, or ability to adapt, many survivors naturally recover some amount of function. An example is a survivor who cannot move an arm at first but finds that a few days later, they can start to wiggle their fingers.
Research using brain imaging shows that in such cases, the brain has rewired control of the fingers to a “neighbouring undamaged area.”
The extent of recovery is closely linked to how well the brain remaps sensory and control functions from the damaged to the undamaged area.
However, the cost of this plasticity is that the brain is constantly trying to free up “real estate” on which to build the new circuits. One way that unused real estate becomes available is when signaling to and from an area stops — for example, when a limb is amputated.
Prof. Lee and his colleagues wondered whether sensory deprivation might be a way to free up real estate near a stroke-injured area, and if the brain would use this opportunity to remap the disabled functions to that area.
Mice with trimmed whiskers healed quicker
To test this idea, they induced stroke in two groups of mice such that it impaired their ability to control their right forepaw.
Following the stroke, they trimmed off the whiskers of one group of mice and left them intact in the other group. Then, they observed the animals’ recovery and their use of the forepaws.
By week 4 after the stroke, the mice with trimmed whiskers had started to use the right forepaw again, and by week 8, they were using them as well as the left forepaw.
However, the mice with intact whiskers recovered much more slowly; by week 4, they were still not using their right forepaw and had only partly recovered use of it by week 8.
Scans of the mice’s brains showed marked differences in both the stroke-affected and neighboring areas. In the brains of the mice with the trimmed whiskers, the activity associated with forepaw use had moved to the area that is normally associated with use of whiskers.
However, in the mice with intact whiskers, the forepaw activity moved to any of several areas next to the injured site.
The following short video from the Washington University School of Medicine sums up the results in the mice:
Whisker-use activity returned to former area
The team allowed the mice with trimmed whiskers to grow them back after they had recovered full use of their right forepaw.
Scans of the animals’ brains taken 4 weeks later showed that whisker-use activity had returned to its former place in the brain. Also, forepaw control stayed in its new place with the mice continuing to show full use of both paws.
The study did not investigate whether the mice that had had their whiskers trimmed lost some ability to use their whiskers.
But the researchers say that there is evidence that when a brain function moves into another part of the brain, it does not impede the function associated with that area.
Prof. Lee gives the examples of musicians and taxi drivers: in musicians, the part of the brain that controls finger movement is unusually large, as is the part that controls navigation in taxi drivers.
“Developing those skills doesn’t cause musicians and taxi drivers to lose any other abilities. They are probably just using their brains more efficiently,” he explains.
He says that their findings show that it may be possible to improve outcomes following stroke by “enhancing plasticity in targeted regions of the brain.”
“We may have to rethink how we do stroke rehabilitation.”
Prof. Jin-Moo Lee
[Abstract] Autonomous rehabilitation at stroke patients home for balance and gait: safety, usability and compliance of a virtual reality system.
Background: New technologies, such as telerehabilitation and gaming devices offer the possibility for patients to train at home. This opens the challenge of safety for the patient as he is called to exercise neither with a therapist on the patients’ side nor with a therapist linked remotely to supervise the sessions.
Aim: To study the safety, usability and patient acceptance of an autonomous telerehabilitation system for balance and gait (the REWIRE platform) in the patients home.
Design: Cohort study.
Setting: Community, in the stroke patients’ home.
Population: 15 participants with first-ever stroke, with a mild to moderate residual deficit of the lower extremities.
Method: Autonomous rehabilitation based on virtual rehabilitation was provided at the participants’ home for twelve weeks. The primary outcome was compliance (the ratio between days of actual and scheduled training), analysed with the two-tailed Wilcoxon Mann- Whitney test. Furthermore safety is defined by adverse events. The secondary endpoint was the acceptance of the system measured with the Technology Acceptance Model. Additionally, the cumulative duration of weekly training was analysed.
Results: During the study there were no adverse events related to the therapy. Patients performed on average 71% (range 39 to 92%) of the scheduled sessions. The Technology Acceptance Model Questionnaire showed excellent values for stroke patients after the training. The average training duration per week was 99 ±53min.
Conclusion: Autonomous telerehabilitation for balance and gait training with the REWIRE-system is safe, feasible and can help to intensive rehabilitative therapy at home.
Clinical Rehabilitation Impact: Telerehabilitation enables safe training in home environment and supports of the standard rehabilitation therapy.
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.)
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
Neuroscientist Michael Merzenich looks at one of the secrets of the brain’s incredible power: its ability to actively re-wire itself. He’s researching ways to harness the brain’s plasticity to enhance our skills and recover lost function.