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How do neurons form new connections in brain plasticity?


I've been reading about brain plasticity and how the brain can "rewire" itself.

One of the things that is not clear to me - how neurons can establish new connections. Does this rewiring mean that neurons can "disconnect" from other neurons to reuse existing dendrites? Or do neurons grow new dendrites to make these new connections, adding to existing ones?

Thank you for your input!


I haven't read anything particularly about dendrites being reshaped, though I would expect them to be as flexible as other parts of the cells.

The more commonly discussed topic (in my literary experience) is reshaping of the axon's branches before forming synaptic terminals. These branches are not fixed even in adults - neurons can grow new and retract old branches, attaching (synapsing) to other cells in new places and removing old connections (see Wikipedia: Synaptogenesis).

Additionally to this actual change in the number of synapses, individual synapses can be regulated in their signal strength by adjusting the number of neurotransmitter receptors in the postsynaptic membrane (Gerrow&Triller, 2010, also see Wikipedia: Synaptic plasticity)


Under conditions where the sensory input to the cortex has been altered, large-scale changes in dendritic branching have been observed after enriched environment experience (e.g. Greenough and Volkmar, 1973) and sensory deprivation (e.g. Tailby et al. 2005). However there is a discrepancy between those post-mortem studies and more modern in vivo studies, where only small-scale changes of the dendritic tips have been observed (Schubert et al. 2013). Large-scale axonal re-arrangements have been also implicated in post-mortem studies after sensory deprivation (e.g. Darian-Smith and Gilbert, 1994) but no such effects have been convincingly described in living animals.

These somewhat different results may be due to several technical limitations: 1) post-mortem studies have utilized injectable tracers and their uptake and/or expression levels may contribute in part to the observed results, 2) in vivo studies have been confined to superficial dendrites due to optical access limitations. Furthermore, these manipulations of the animal's experience are relatively crude ways of probing cortical circuits and do not necessarily reflect the processes that the brain may use under more physiological conditions.

By far the most well described processes under enriched environment experience, sensory deprivation and sensory stimulation, and learning paradigms are microscopic changes at the level of individual synapses. These include increased synaptic turnover (Trachtenberg et al. 2002, Xu et al. 2009), synaptic stabilization (Holtmaat et al. 2006), and synaptic strength changes (Hofer et al. 2009). These microscopic changes provide a very economical way, in comparison to large-scale dendritic or axonal re-arrangements, in which neuronal circuits can be extensively rewired given the enormous potential of dendritic spines and boutons to sample different synaptic partners (Stepanyants et al. 2002).


References

Darian-Smith, C., & Gilbert, C. D. (1994). Axonal sprouting accompanies functional reorganization in adult cat striate cortex. Nature, 368(6473), 737-740. https://doi.org/10.1038/368737a0

Greenough, W. T., & Volkmar, F. R. (1973). Pattern of dendritic branching in occipital cortex of rats reared in complex environments. Experimental Neurology, 40(2), 491-504. https://doi.org/10.1016/0014-4886(73)90090-3

Hofer, S. B., Mrsic-Flogel, T. D., Bonhoeffer, T., & Hübener, M. (2009). Experience leaves a lasting structural trace in cortical circuits. Nature, 457(7227), 313-317. https://doi.org/10.1038/nature07487

Holtmaat, A., Wilbrecht, L., Knott, G. W., Welker, E., & Svoboda, K. (2006). Experience-dependent and cell-type-specific spine growth in the neocortex. Nature, 441(7096), 979-983. https://doi.org/10.1038/nature04783

Schubert, V., Lebrecht, D., & Holtmaat, a. (2013). Peripheral Deafferentation-Driven Functional Somatosensory Map Shifts Are Associated with Local, Not Large-Scale Dendritic Structural Plasticity. Journal of Neuroscience, 33(22), 9474-9487. https://doi.org/10.1523/JNEUROSCI.1032-13.2013

Stepanyants, A., Hof, P. R., & Chklovskii, D. B. (2002). Geometry and structural plasticity of synaptic connectivity. Neuron, 34(2), 275-88. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/11970869

Tailby, C., Wright, L. L., Metha, A. B., & Calford, M. B. (2005). Activity-dependent maintenance and growth of dendrites in adult cortex. Proceedings of the National Academy of Sciences, 102(12), 4631-4636. https://doi.org/10.1073/pnas.0402747102

Trachtenberg, J. T., Chen, B. E., Knott, G. W., Feng, G., Sanes, J. R., Welker, E., & Svoboda, K. (2002). Long-term in vivo imaging of experience-dependent synaptic plasticity in adult cortex. Nature, 420(6917), 788-94. https://doi.org/10.1038/nature01273

Xu, T., Yu, X., Perlik, A. J., Tobin, W. F., Zweig, J. a, Tennant, K.,… Zuo, Y. (2009). Rapid formation and selective stabilization of synapses for enduring motor memories. Nature, 462(7275), 915-9. https://doi.org/10.1038/nature08389


Researchers find a new plasticity mechanism in neural connections

Neurons are able to detect the loss of autaptic synapsis -established by themselves- and recover the reduction of nervous neurotransmission through the formation and promotion of new connections. This is the main conclusion of the new article published in the journal Communications Biology, by researchers Artur Llobet and Cecília Velasco, members of the Faculty of Medicine and Health Sciences, the Institute of Neurosciences of the UB (UBNeuro) and the Bellvitge Institute for Biomedcal Research (IDIBELL).

The team led by Llobet had described in previous studies the ability of SPARC protein -secreted factor by glial cells in the nervous system- to remove synapsis. However, there were many doubts on the used mechanism by this protein and the target synapses.

Surprisingly, a series of following experiments to study the activity of SPARC protein revealed that those neurons exposed to the action of this factor showed an early fall into neurotransmission, an ability that could be then recovered with the present SPARC. Therefore, neurons expressed a new homeostatic presynaptic plasticity mechanism, which contributes to maintain the right neurotransmission levels in the neural circuits.

According to the lecturer Llobet, “we wanted to describe the action selectivity of SPARC on the synapses and we ended up doing research on a new plasticity mechanism”. The fast recovery of autaptic synapses in the experimental trials “shows that neurons could use these contacts to detect a reduction in the neurotransmission and therefore, create new synapses to re-establish the base levels”, notes Cecília Velasco, first author of the study.


Summary

Effective learning takes advantage of the brain’s plasticity. Neural networks are groups of neurons that fire together, creating electrochemical pathways. When you continuously access a memory associated with something new that you’re learning, these neural networks shape themselves according to that activity or memory.

Think of it this way in a city with many road networks, the more cars plying a certain route, the wider it needs to be. When you stop accessing memories associated with what you’re learning, your brain will eventually eliminate, or “prune” the connecting cells or neurons that formed the pathways.

The secret lies in time and conscious effort. So, you become very good at anything by helping your brain reshape itself through consistent practice and persistent effort.

Discussion

What do you think about the ideas shared in this article about neuroplasticity? Does the idea of brain plasticity make any sense to you? Are there some things you used to do badly before that you’ve become much better at? Leave your comments below.

See more articles that can help you become better at learning >>

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How schools should leverage brain plasticity and the neuroscience of learning

Have you ever heard the term “brain plasticity”? This does not mean that the brain is made of plastic, of course. Brain plasticity or neuroplasticity is the unique ability of the brain to change due to forging new connections with other neurons. Research suggests that human brain development takes about 25 years and that the rate of progress depends on nature and nurture. The more connections the brain forms, the faster the course of development will be.

Does that mean that brain development stops at the age of 25 years? This article will examine how the brain develops from birth and the role played by nature and the environment.

How Brain Plasticity Changes At Different Ages‍

From Birth to Age Five

The child’s brain development at this stage is the fastest. It has been proven that the changes and growth in the brain happen most in the earliest years of human life. The quality of experiences that nurture the first few years of a child’s life has a significant role in how their brain develops. Evidence suggests that early childhood care and education, when done successfully, lays the groundwork for cognitive development and executive function throughout the child’s life. The first five years of life are the best opportunity for the brain to make significant progress. Positive experiences in the child’s early life help children to be healthy, capable and successful as adults. High-level abilities like motivation, self-regulation, critical thinking and communication are formed in these early years.

Unfortunately, the opposite is true as well. Trauma, poverty and an unstable childhood can negatively impact a child’s early brain development and eventually affect their adulthood.

Six to Eleven Years Old

As children age, their brain continues to develop. More complex behavioural and cognitive development takes place in middle childhood: between 6 to 11 years of age. In the early part of this stage, the brain goes through a spurt of growth, so by the time children are between 8 or 9 years old, they are expected to have a nearly fully grown, adult-sized brain. Brain development in the latter part of middle childhood is characterised by the growth of specific structures in the brain’s frontal lobe. The frontal lobe sits under the skull at the front of the brain and is responsible for executive functions, such as planning, organising, reasoning, moral judgment and decisions. This is where making good choices becomes intrinsic, rather than influenced by extrinsic motivation.

Adolescence

The prefrontal cortex part of the brain continues to develop at this stage and goes through significant changes before it can fully function as an adult brain. This brain re-modelling is intensive during adolescence until the child’s mid-20s. The physical and hormonal changes in teenagers directly affect the development of the brain. If puberty strikes early, then some of the brain changes will also occur earlier. Research shows that teenagers rely on the part of the brain called the amygdala to make decisions and solve problems.

Re-modelling of the brain is a continuous phenomenon and experienced by everyone, even as they become adults. There are a few scientifically-researched principles for how we remodel our brains in adulthood. These include:

  • Use It Or Lose It: “Pruning” is an essential activity in the human brain. It is a way for the brain to become more efficient. Unused connections in the thinking and processing part of the brain are removed hence, the term “use it or lose it”. Neuroplasticity is the brain’s ability to reorganise itself by forming new neural connections.
  • Use It Or Improve It: The keyword here is “continuous training”. Persistent, continuous brain training and behavioural experiences can enhance what is being learned and aid in forming new connections in the brain thus, learning and relearning occur. This is also true in cases of trauma the brain can be retrained and rehabilitated for individuals to regain knowledge and skills and improve their functional capacity.
  • Learning While You Sleep: It is often discussed how important it is to get a good night's sleep. This is particularly important for brain development and for improving brain plasticity through the creation of new neural pathways. The current evidence suggests that the brain reinforces the neural pathways created while awake during sleep, making a more robust network of neurons.

The Link Between Brain Plasticity Principle and Education

While our brains can change well into adulthood, it is believed that younger minds are easier to train. From a school’s point of view, It is important to consider each individual child’s learning style and age and consider previous experiences they have had in their lives. To help their brain develop, there are some key factors to consider:

  • Time: It is never too early to start. Early intervention is the key to success. Intensify the training for the desired behaviour, rehabilitate as early as possible in unlearning and relearning skills. It is not an easy task, but it is achievable with practice, persistence and patience.
  • Relevance: Creating a meaningful and engaging learning environment helps children develop their cognitive and physical skills and create new neural pathways. To optimise plasticity, the child’s experiences within a learning environment should be directed towards the skills that wish to be acquired. It is also important that these experiences relate to real-world scenarios and can be practised over again.
  • Age:Does age matter? Absolutely! Age and readiness are essential factors in acquiring new skills. Nature and nurture enhance learning. This means children must be physically, cognitively and emotionally ready to learn and develop new skills. Although we have said that it is never too early to start, it is vital to ensure that the teaching styles and learning outcomes are appropriate for the child's age. Physical, cognitive and emotional readiness plays a big part in behavioural change, so it is essential to keep in mind that every child grows and develops at their own pace.
  • Intensity: The saying practice makes perfect holds true for acquiring new knowledge and behaviour for children. By repeating an activity, building memory recall and revisiting learning through different lenses, the connections between neurons in the brain become stronger.

OWIS Applies the Principles of Brain Plasticity for Optimal Learning

Our OWIS educators take all of these aspects of neural plasticity into consideration when teaching students. They understand that some children will be ready to start learning new skills at a younger age than others, so it is important to assess each child’s needs and make adaptations wherever necessary.

Our curriculum also takes these factors into account and has been rigorously tested by the IBO and Cambridge to ensure that learning outcomes and long term development are achieved. We continue to assess our learning programmes and adapt when needed to ensure that we are giving our students lifelong skills.

Inquiry-based Learning and Brain Plasticity

OWIS ensures continuous, timely, meaningful and relevant education for our young learners. Through inquiry-based learning, the students at OWIS think and act on their learning based on the concept’s relevance in every unique child’s experience. Daily hands-on experiences and concept exploration relevant to the students create strong neural connections.

Through inquiry-based learning, the brain works harder to make meaning of their experiences thus, it helps to hone critical and creative thinking. Neuroplasticity suggests that our brain connects, disconnects and creates new connections as we strive, take risks and learn from our experiences. Failure, risk and improvement play an integral process in learning.

Mindfulness: a Key to Reflection

Mindfulness, which is also an essential part of learning at OWIS, boosts neural activity. The brain benefits from both high stimulus and meditative stillness. This also includes the process of metacognition, where the children are given opportunities to think about their own learning. This helps the child create a meditative look on their own performance. We achieve this at OWIS when students plan, assess and construct their learning as they explore a concept.

Student Agency and Ownership of Learning

How do we create opportunities for relevance and profound learning? Simply by allowing our students to take ownership of their learning.

Designing an innovative curriculum where teachers can create remarkable opportunities based on the students’ prior knowledge and what they want to know is an essential part of profound learning experiences. Learning is not something that students are forced to do. Students’ voices and choices are powerful strategies for allowing students to find themselves in their learning.

At OWIS, we value students’ agency and decisions. We recognise that by allowing for student agency, we can help students discover themselves, their skills and abilities. Enabling the students to have a voice in class makes responsible, thoughtful adults who will develop into morally responsible citizens of the world.

At OWIS, we strive to create lifelong learners who are passionate about gaining new skills and knowledge. We use a range of different teaching styles and techniques to ensure that our students’ brain development is given the best opportunity to be the best it can be.

We educate our students relative to their age and ensure that appropriate lessons and play are encouraged at different ages to promote the development of brain plasticity. We understand that each child is an individual and that each student may learn in different ways and that they should be encouraged to find their own learning style so that they can continue to develop their brain plasticity throughout their lives. ‍

Contact us to learn more about how our programmes encourage children to reach their highest potential.


Motor neurons (green) form synapses (highlighted in magenta) on muscle fibers in a fruit fly. MIT neuroscientists have discovered a pathway that contributes to strengthening these synapses.

When the brain forms memories or learns a new task, it encodes the new information by tuning connections between neurons. MIT neuroscientists have discovered a novel mechanism that contributes to the strengthening of these connections, also called synapses.

At each synapse, a presynaptic neuron sends chemical signals to one or more postsynaptic receiving cells. In most previous studies of how these connections evolve, scientists have focused on the role of the postsynaptic neurons. However, the MIT team has found that presynaptic neurons also influence connection strength.

“This mechanism that we’ve uncovered on the presynaptic side adds to a toolkit that we have for understanding how synapses can change,” says Troy Littleton, a professor in the departments of Biology and Brain and Cognitive Sciences at MIT, a member of MIT’s Picower Institute for Learning and Memory, and the senior author of the study, which appears in the Nov. 18 issue of Neuron.

Learning more about how synapses change their connections could help scientists better understand neurodevelopmental disorders such as autism, since many of the genetic alterations linked to autism are found in genes that code for synaptic proteins.

Richard Cho, a research scientist at the Picower Institute, is the paper’s lead author.

Rewiring the brain

One of the biggest questions in the field of neuroscience is how the brain rewires itself in response to changing behavioral conditions — an ability known as plasticity. This is particularly important during early development but continues throughout life as the brain learns and forms new memories.

Over the past 30 years, scientists have found that strong input to a postsynaptic cell causes it to traffic more receptors for neurotransmitters to its surface, amplifying the signal it receives from the presynaptic cell. This phenomenon, known as long-term potentiation (LTP), occurs following persistent, high-frequency stimulation of the synapse. Long-term depression (LTD), a weakening of the postsynaptic response caused by very low-frequency stimulation, can occur when these receptors are removed.

Scientists have focused less on the presynaptic neuron’s role in plasticity, in part because it is more difficult to study, Littleton says.

His lab has spent several years working out the mechanism for how presynaptic cells release neurotransmitter in response to spikes of electrical activity known as action potentials. When the presynaptic neuron registers an influx of calcium ions, carrying the electrical surge of the action potential, vesicles that store neurotransmitters fuse to the cell’s membrane and spill their contents outside the cell, where they bind to receptors on the postsynaptic neuron.

The presynaptic neuron also releases neurotransmitter in the absence of action potentials, in a process called spontaneous release. These “minis” have previously been thought to represent noise occurring in the brain. However, Littleton and Cho found that minis could be regulated to drive synaptic structural plasticity.

To investigate how synapses are strengthened, Littleton and Cho studied a type of synapse known as neuromuscular junctions, in fruit flies. The researchers stimulated the presynaptic neurons with a rapid series of action potentials over a short period of time. As expected, these cells released neurotransmitter synchronously with action potentials. However, to their surprise, the researchers found that mini events were greatly enhanced well after the electrical stimulation had ended.

“Every synapse in the brain is releasing these mini events, but people have largely ignored them because they only induce a very small amount of activity in the postsynaptic cell,” Littleton says. “When we gave a strong activity pulse to these neurons, these mini events, which are normally very low-frequency, suddenly ramped up and they stayed elevated for several minutes before going down.”

Synaptic growth

The enhancement of minis appears to provoke the postsynaptic neuron to release a signaling factor, still unidentified, that goes back to the presynaptic cell and activates an enzyme called PKA. This enzyme interacts with a vesicle protein called complexin, which normally acts as a brake, clamping vesicles to prevent release neurotransmitter until it’s needed. Stimulation by PKA modifies complexin so that it releases its grip on the neurotransmitter vesicles, producing mini events.

When these small packets of neurotransmitter are released at elevated rates, they help stimulate growth of new connections, known as boutons, between the presynaptic and postsynaptic neurons. This makes the postsynaptic neuron even more responsive to any future communication from the presynaptic neuron.

“Typically you have 70 or so of these boutons per cell, but if you stimulate the presynaptic cell you can grow new boutons very acutely. It will double the number of synapses that are formed,” Littleton says.

The researchers observed this process throughout the flies’ larval development, which lasts three to five days. However, Littleton and Cho demonstrated that acute changes in synaptic function could also lead to synaptic structural plasticity during development.

“Machinery in the presynaptic terminal can be modified in a very acute manner to drive certain forms of plasticity, which could be really important not only in development, but also in more mature states where synaptic changes can occur during behavioral processes like learning and memory,” Cho says.

The study is significant because it is among the first to reveal how presynaptic neurons contribute to plasticity, says Maria Bykhovskaia, a professor of neurology at Wayne State University School of Medicine who was not involved in the research.

“It was known that the growth of neural connections was determined by activity, but specifically what was going on was not very clear,” Bykhovskaia says. “They beautifully used Drosophila to determine the molecular pathway.”

Littleton’s lab is now trying to figure out more of the mechanistic details of how complexin controls vesicle release.


Neuroplasticity: The Process Of Rewiring Your Brain and its Everyday Applications

The human brain is an organ of perpetual reconstruction. Composed of, on average, eighty-six billion neurons, the brain’s cells are able to chemically intercommunicate and fire trillions of signals to one another each second. Functioning alongside its immeasurably fast neurological transmissions is the brain’s plasticity. Take the recent case of an epileptic patient publically referred to by the initials of “U.D.”. U.D. was an adolescent boy that had grappled with tumor-induced seizures that failed to abate with the introduction of medication. After having exhausted all other options, both physicians and U.D. 's family agreed to the removal of his tumor. This, however, required the removal of a third of the right hemisphere of his brain. Following the surgery, U.D. was without his right occipital and temporal lobes. Astonishingly, in addition to diminishing his chronic seizures, U.D. suffered minimal permanent damage to his brain. Upon analysis of his brain functioning post surgery, scientists found that his left hemisphere had compensated for the visual and auditory roles that his right hemisphere once maintained.

U.D. serves as a prime model of the brain’s ability to adapt and remodel itself and its functioning. Given the brain’s demonstrated capability in even the most extreme situations, it should come to no surprise that the brain’s neuroplasticity, or ability to create and change its neurons, are affected by a plethora of genetic and environmental factors. Daily habits, such as level of exercise, as well as the internal psychological interpretation of ourselves and the world around us, impact the brain’s biology. Studies have shown that, on a microscopic level, brain rewiring occurs through neurogenesis the process of generating additional neurons in the brain. Stimulating this process can lead to favorable shifts in mental health and general cognitions.

One proven method of increasing the neuroplasticity of the brain is through music. The simple process of listening to music serves as a stimulant for the neurons in the brain and allows for new connections between them to form. A study focusing on the impact of listening to Motzart resulted in an increase of memory and processing functions while, and after, listening to the composer than that of the control group. Music is often used as a method to boost mood and, when paired with the fact that it has the ability to interact with the brain’s cells that betters cognitive function, reinforces the benefit of music to physiologically reshape your cognitions. Another effective tool to activate neuroplasticity is physical exercise. Exercise has been linked to decreasing, and sometimes reversing, the rates at which stress and mental health disorders burden the brain. Through improving neurological functioning and activating endorphins within the body, exercise, especially when done over a sustained period of time, decreases the severity that mentally strenuous situations have on the brain.


How do neurons form new connections in brain plasticity? - Biology

New research identifies how the birth of new neurons can reshape the brain.
Posted Feb 06, 2017


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 (link is external)” 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 (link is external) and Jacques Wadiche (link is external)—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 (link is external) 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 (link is external).)

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:

  1. 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?
  2. 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 (link is external), 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 (link is external) (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 (link is external)."

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 (link is external)


How neurons form new connections

In the human brain, new connections are continually created while synapses that are no longer used disintegrate. To date, little is known about how this process works. Researchers from Germany and The Netherlands have now discovered that the structural plasticity in the visual cortex can be attributed to a simple homeostatic rule.

"And it's not just about learning. Following the amputation of extremities, brain injury, the onset of neurodegenerative diseases, and strokes, huge numbers of new synapses are formed in order to adapt the brain to the lasting changes in the patterns of incoming stimuli", says study leader Markus Butz from the Forschungszentrum Juelich (Juelich Research Center). By using computer simulations, scientists reconstructed the reorganisation of neurons in a way that complies with experimental results from the visual cortex in mice and monkeys.

According to a report published in "PLOS Computational Biology", the new formation of synapses is driven by the effort of the neurons to maintain a predefined electrical activity level. If the average electrical activity falls below a certain level, the neuron actively begins to build new contact points as a basis for new synapses. When the activity level exceeds an upper limit, the number of synapse connections is reduced and thereby counteracts overexcitation.

However, this is not possible without a certain excitation. "A neuron that no longer receives any stimuli loses even more synapses and will die off after some time. We must take this restriction into account if we want the results of our simulations to agree with observations", says Blutz.

"The new growth rule provides structural plasticity with a principle that is almost as simple as that of synaptic plasticity", explains co-author Arjen van Ooyen. But since structural plasticity extends over longer periods of time - from several days to months - it is of prime importance especially for the rehabilitation of patients affected by a neurological disease.

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Neural Plasticity: How to Use Your Mind to Change Your Brain

Mental activity strengthens the neural pathways in your brain associated with what you focus on with your thoughts and feelings. To oversimplify this—but, nonetheless, clearly state what is happening—if you focus on happiness with your thoughts and feelings, you strengthen happiness pathways. If you focus on stress with your thoughts and feelings, you strengthen stress pathways. Every thought you think and feeling you feel, strengthens the circuitry in your brain known as your neural pathways. Neural pathways are the basis of your habits of thinking, feeling, and acting. They are what you believe to be true and why you do what you do. Donald Hebb’s landmark discovery in 1949, “neurons that fire together wire together,” best explains the process of forming, strengthening, and solidifying neural pathways.4 We experience these pathways as our patterns in important areas of our life such as relationships, food, money, career, health and happiness levels.


Sources

2. Herculano-Houzel S. The human brain in numbers: a linearly scaled-up primate brain . Front Hum Neurosci. 20093:31. Published 2009 Nov 9. doi:10.3389/neuro.09.031.2009

3. The University of Queensland. What are neurotransmitters?

4. Cherry, Kendra. VeryWellHealth: Synapses in the Nervous System.

5. Wikipedia: Neuroplasticity.

6. Kalat, James W. Biological Psychology . North Carolina State University.

7. Chayer, Cèline & Freedman, Morris. (2001). Frontal lobe functions . Current neurology and neuroscience reports. 1. 547-52. 10.1007/s11910-001-0060-4.


Watch the video: Slow Motion of Neurons Forming New Connections. Your Thoughts Look Like This (January 2022).