Posts Tagged ‘Neurogenesis’

Less Hippocampus, More Caudate Nucleus

January 24, 2020

This post is based on text from Wayfinding, a book by M.R. O’Connor.
Bohbot is concerned that the conditions of modern Life are leading us to flex the hippocampus less while spurring us to rely on the caudate nucleus. She says, “Maybe in the past we never had to go on autopilot. Having jobs in one location and lives being more habitual is new. Industrialization learned to capitalize on the habit-memory-learning system.” HM is in strong agreement with Dr. Bohbot.

Chronic stress, untreated depression, insomnia, and alcohol abuse all can shrink hippocampal volume. Anxiety alone has been shown to impact the spatial learning and memory of rats. Stress and depression seem to affect neurogenesis in the hippocampus, whereas exercise seems to improve learning, memory and resistance to depression, which spurs a proliferation of new neurons. Patients with PTSD have been shown to have lower hippocampal volume. One of the consequences of effective treatment for this disorder such as the use of antidepressants and changes in environment, is increased hippocampal volume.

Bohbot has been led by the widespread prevalence of these conditions to be concerned that by the time children enter young adulthood, they might already have relatively shrunken hippocampal volume that makes them susceptible to cognitive and emotional impairments and behavioral problems. An over reliance on stimulus-response navigation strategies seems connected to a host of destructive yet seemingly unrelated behaviors. Because the circuit is located in the striatum, a brain area involved in addiction, Bohbot started to wonder: Would people who rely on a response strategy to navigate show any difference in substance abuse from those who relied on spatial strategies? In 2013 she published a study of 55 young adults that showed those who relied on response strategies in navigating had double the amount of lifetime alcohol consumption, in addition to more use of cigarettes and marijuana. In a different study of 255 children, she found that those with ADHD symptoms primarily rely on caudate nucleus stimulus strategies. Recently, Bohbot and Greg West showed that ninety hours of in-lab action video games will shrink the hippocampus of young adults who used their caudate nucleus. This is the first clear evidence that the activities we engage in can have negative impact on the hippocampus.

In 2017, Bohbot along with ten researchers published a report called, “Global Determinants of Navigational Ability,’ in which they looked at the performance of 2.5 million people globally on a virtual spatial navigation task. Then they broke the data down to understand whether there were similar profiles in cognitive abilities among countries. The data are that spatial navigation ability starts declining in early adulthood, around nineteen years of age, and steadily slips in old age. People from rural ares were significantly better at the game. When it came to countries themselves, Australians, South Africans, and North American showed generally good spatial orientation skills, but the real outliers were Nordic countries.

Developing Emotional Intelligence

March 10, 2019

This title of this post is the same as the title of a chapter in Daniel Goleman’s book “The Brain and Emotional Intelligence: New Insights.” Every day the brain generates 10,000 stem cells that split into two. One becomes a daughter line that continues making stem cells, and the other migrates to wherever it’s needed in the brain and becomes that kind of cell. That destination is often where the cell is needed for new learning. Over the next four months, that new cell forms about 10,000 to created new neural circuitry.

The state of the art in mapping this neural circuitry coming out of labs like Richard Davidson’s have massive computing power. Innovative software tools for brain imaging can track and show this new connectivity at the single-cell level. Neurogenesis adds power to our understanding of neuroplasticity, that the brain continually reshapes itself according to the experiences we have. If we are changing a habit like trying to get better at listening, then that circuitry grows accordingly. However, when we are trying to overcome a bad habit, we’re up against the thickness of the circuitry for something we’ve practiced and repeated thousands of times. Goleman asks, “So what are the brain lessons for coaching or for working on our own to enhance an emotional intelligence skill?”

Number one, is to get committed. Mobilize the motivating power in the left prefrontal areas. If you’re a coach, you’ve got to engage the person, get them enthused about achieving the goal of change. Here it helps to draw on their dreams, their vision for themselves, where they want to be in the future. Then work from where they are to what they might improve to help them get where they want to go in life. Change this section from the third person to the second person for self instruction.

Be very practical. Don’t take on trying to learn too much all at once. Operationalize your goal at the level of a specific behavior. Make it practical, so you can know exactly what to do and when. For example, say someone has a bad habit of multi-tasking and essentially ignoring others, which undermines the full attention that can lead to rapport and good chemistry. You have to break the habit of multitasking. So the person might make up an intentional learning plan that says something like: at every naturally occurring opportunity-when a person walks into your office, stand, or you come up to a person—you turn off your cell phone and your beeper, turn away from your computer, turn off your daydream or your preoccupation and pay full attention. That gives you a precise piece of behavior to try to change. Goleman continues, “So what will help you with that? Noticing when a moment like that is about to come and doing the right thing. Doing the wrong thing is a bit that you have become an Olympic level master at—your neural working has made it a default option, what you do automatically. The neural connectivity for that is strong. When you start to form the new better habit, you’re essentially creating new circuitry that competes with your old habit in a kind of neural Darwinism. To make the new habit strong enough, you’ve got to use the power of neuroplasticity—you have to do it over and over again.

If you persist in the better habit, that new circuitry will connect and become more and more powerful, until one day you’ll do the right thing in the right way without a second thought. That means the circuitry has become so connected and thick that this is the brain’s new default option. With that change in the brain, the better habit will become your automatic choice.

For how long and how many times does an action have to be repeated until it’s hard-wired? A habit begins to be hard-wired the first time you practice it. How often you have to repeat so that it becomes the new default of the brain depends in part on how strong the old habit is that it will replace. It usually takes three to six months of using all naturally occurring practice opportunities before the new habit becomes more natural than the old.”

Mental rehearsal is another practice opportunity that can occur whenever you have a little free time. Mental rehearsal activates the same neural circuitry as does the real activity. Olympic athletes spend off-season running through the moves in their brain. This counts as practice time. It increase their ability to perform when the real time comes.

Goleman writes that Richard Boyatwzis has used this method with his MBA students at the Weatherhead School of management at Case Western University. He’s followed these students into their jobs as much as seven years later and found the competencies they had enhanced in his class were still rated as strong by their co-workers.

Ten Fundamentals of Brain Plasticity

August 3, 2016

These ten fundamentals come from Dr. Merzenich’s book, “Soft-Wired” with elaboration and comments by Healthy Memory (HM).

1. Change is mostly limited to those situations in which the brain is in the mood for it.
If you force it the learning will be inefficient and of poor quality.  I find it surprising that Dr. Merzenich, in spite of his participation in the conferences at Mind and Life Institute in Dharmsala, India  with the Dalai Lama that have demonstrated the pronounced effects of meditation, he makes no mention of meditation.  Meditation is one of the best, if not the best, means of restoring the mind.

2.  The harder we try, the more we are motivated, the more alert we are, and the better (or worse) the outcome, the bigger the brain change.
Once again HM marvels that Dr. Merzenich, in spite of his participation in the conferences at Mind and Life Institute in Dharmsala, India  with the Dalai Lama that have demonstrated the pronounced effects of meditation.  Meditation provides an ideal means of gaining control of one’s attention, and an ideal means of focusing attention.

3.  What actually changes in the brain are the strength of the connections that are engage together, moment by moment, in time.
Both neurorgenesis, the forming of new neurons, and synaptogenesis, the forming of new connections among neurons are involved.  It is also important to realize that these neurons are not necessarily adjacent to each other.  Neurons transmit signals through axons that can be quite long.  So a single neuron in the prefrontal cortex can be sending a signal to another neuron in a distant part of the brain.  These connections can be quite long and complicated.  Their interactions have been described as being conversations within the brain.

4.  Learning-driven changes in connections increase cell-to-cell cooperation, which is crucial for increasing reliability.
So the process of learning involves increasing this cell-to-cell cooperation, cells which can be quite far apart depending upon the type of learning, and the reliability of the learning.

5.  The brain also strengthens the connections between those teams of neurons representing separate moments of activity that represent each little part of an action or thought.
So these signals need to be strengthened in terms of the time sequence of the actions or thoughts.

6  Initial changes are just temporary.
So with the exception of certain extraordinary conditions, these changes will be lost unless they are strengthened by further activity.

7.  The brain is changed by internal mental rehearsal in the same ways, and involving precisely the same processes, that construct changes with the external world
So thinking alone will strengthens these processes.  Thinking and mental rehearsal are very important.

8.  Memory guides and controls most learning.
Indeed, memory is key.  Memory is a device for time travel.  It reviews what it can find in memory and then uses it to solve problems, to consider alternative courses of action, to make a joke, or for pleasure.

9.  Every moment of learning provides a moment of opportunity for the brain to stabilize and to reduce the disruptive power of—potentially interfering and background or “noise.
This is all good.

10.  Brain plasticity is a two-way street; it is just as easy to generate negative changes as it is to produce positive ones.
So brain activity can be destructive.  Thinking negative thoughts and having a fixed mindset are damaging and do not allow us to fulfill our potential.  HM is reminded of an incident that took place in his last place of employment.  He was riding down in an elevator and one of the fellow passengers in the elevator remarked to his friend, that when he retired he was going to do absolutely nothing.  If all he could find on television were Luci reruns,, he would just watch “I Love Lucy.”  HM would place a large wager that serious dementia was not too far in this individual’s future.

HM would like to add a couple of more comments.
Please read the healthy memory blog post “The Myth of Cognitive Decline”, and “More on the Myth of Cognitive Decline.”  The longer we live, the more we have in memory, and if we have growth mindsets we have even more in memory.  This might appear to slow us down, but in reality we have rich mindsets with brains with many long interconnections within them.  In addition to adding to these mindsets it is healthy to review old memories.  Writing a biography or a family history can be enriching.

It is also important to realize that our brains continue to work even when you stop thinking about something.  My wife and I are frustrated when we know something, the name of an actress,for example, but can’t remember it.  We become frustrated, but find that the name comes into consciousness, unsolicited at some later time.  HM thinks this is very healthy, so he resists trying to google something that he is sure he knows.  He will try for a while to remember it.  He knows that when he stops consciously thinking about it, his brain will continue searching and will probably eventually find it.  HM believes that this unconscious bran activity is reactivating memory circuits and providing for memory health.

© Douglas Griffith and, 2016. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and with appropriate and specific direction to the original content.

Now What?

June 16, 2016

“Now What” is the title of the final chapter in Sharon Begley’s outstanding book, “Train Your Mind, Change Your Brain:  How a New Science Reveals Our Extraordinary Potential to Transform Ourselves.”   The answer to this question is that the future has arrived and that we are the beneficiaries of a revolution in the understanding of the brain and human potential.

There are three key discoveries.  One is that neurons are created until we die.
The second is neuroplasticity that the brain can rewire itself.
The third is that we can effect these changes with how with think, that is, with our minds.  Hence the title, “Train Your Mind, Change Your Brain.

Sometimes there are problems in the brain, and these can be corrected  by the way we think and exercises that can effectively make corrections to our neuroplastici brains.  But we can also build upon and improve our minds.  The future is virtually limitless.
Begley reviews some of the exciting research of Merzenich, which shall not be reviewed here as there shall be many future posts about the work of Merzenich.

A critical topic is that of secular ethics, a term Healthymemor believes was coined by the Dalai Lama.  The Dalai lama does not proselytize for Buddhism.  Rather he argues for a new basis for a modern ethics, one that appeals to the billions of people who adhere to different religions or to no religion, one that supports basic values such as personal responsibility, altruism, and compassion.

The problem is that a scientific literate person or anyone who gives a cursory glance at newspaper science stories may well react to that a message with some skepticism.  Modern science seems to be offering a radically different view of human responsibility.  Critics call this view neurogenetic determinism, the belief, ascendant from the early 1990s and propelled by the mystique of modern genetics, that ascribes causal power to the genres one inherent from one’s parents.  Should a reader still adhere to this view they are urged to read or reread all the posts devoted to Begleys book.  Genes are affected by the environment and, what is important, are epigenetic, which refers to what is read out from genes.  The environment has strong effects as do meditative practices.  There is a related wrong view and that is strict determinism.  We are victims to neither our genes nor to our environments.  Our minds, how we think about the world along with meditative practices, can and do effect changes.

Healthy memory shall conclude this post with the Begley’s final paragraph.  “The conscious act of thinking about one’s thoughts in a different way changes the very brain circuits that do that thinking, as studies show how psychotherapy changes the minds of people with depression show.  Such willfully induced brain changes require focus, training, and effort, but a growing number of studies show how real those changes are.  They come from within.  As discoveries of neuroplasticity, and this self-directed neuroplasticity, trickle down to clinics and schools and plain old living rooms, the ability to willfully change the brain will become a central part of our lives—and our understanding what it means to be human.”

More on the Hippocampus: Key to Human Memory

February 14, 2016

I neglected to mention in the previous post another, and perhaps more promising approach, than an artificial  hippocampus is to enhance neurogenesis in the hippocampus.  Neurogenesis in the hippocampus is supposed to continue throughout our lifetime, but it is likely that cognitive deficits are due to decreases or stoppages in hippocampal neurogenesis.  So restarting and/or enhancing neurogenesis might improve cognitive functioning.

© Douglas Griffith and, 2016. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and with appropriate and specific direction to the original content.

The Adult Brain Makes New Neurons and Effortful Learning Keeps Them Alive

October 19, 2014

The title of this blog post is the same title as an article in Current Directions in Psychological Science 2014 23:311 (DOI: 10.1177/0963721414540167) by Tracey J. Shors of Rutgers University.. The healthymemory blog has posted many pieces emphasizing that new neurons continue to be developed until we die. The hippocampus produces thousands of new neurons each day. Unfortunately a significant number of them die and do so within just a few weeks after their birth. So the critical question is how to save these neurons from an untimely death.

As the title states the answer is effortful learning. Although the cited research did not involve human subjects, two important facts need to be remembered. It is difficult and expensive to conduct similar research with humans. And findings from the vast majority of research using non-human subjects do generalize to population of humans.

It has been noted many times in the healthymemory blog that physical exercise facilitates neurogenssis. However, many of these new cells do not survive. It takes effortful learning for there to be a lasting preferential effect on the survival of these new neurons.

Fortunately Dr. Shors concluded the article with a discussion of the relevance of these findings for humans. Here are four recommendations:

  1. spacing trials of training or learning over longer periods of time. (which has been discussed in previous healthymemory blog posts).

  2. Self-testing (which has been mentioned on previous healthymemory blog posts).

  3. varying the conditions of training or learning

  4. interleaving different topics and/or skills within the same training session.

The fourth item on interleaving different topics or skills might sound like a contradiction of the many healthymemory blog posts warning against the dangers of multi-tasking. The difference here is the time laps between switching. Here the time laps are substantially longer than those commonly done in multi-tasking.

The four recommendations provide vice on how to do new learning. The two important points for the survival of new neurons are:

  1. Learn new knowledge of skills.

  2. The learning should be effortful, requiring mental effort.

You Can Teach an Old Dog New Tricks

October 8, 2014

This post is based on “Old dog, new tricks” in The Scientific Guide to a Better You: New Scientist: The Collection. The saying “you can’t teach an old dog new tricks” has been around for a long, long time. Too long, in fact, to hold under the new findings in science. Neurogenesis continues as long as we live, as well as the ability to learn new things.

I had long believed that there was a critical age for language acquisition. The idea was that we were designed to pick up languages naturally at an early age. However, after the onset of puberty, the task became more difficult. A study by Ellen Bialystok at York University in Toronto, Canada, disabused me of this notion. She studied US census records that detailed the linguistic skills of more than 2 million Hispanic and Chinese immigrants. If there had been a “critical period” for learning a second language in infancy should have created a sharp difference between those who changed country in early childhood and those who were uprooted in adolescence. There was no sharp difference. Rather there was a very gradual decline with age among immigrants. This could reflect differences in environment as well as adults’ rusty brain circuits. It is not that old dogs can’t learn, but rather a matter of old dogs not expending the effort to learn.

Gary Marcus, a psychologist devoted himself to learning how to play the guitar when he was 38. He wrote a book on his experience titled Guitar Zero. Initially his family laughed at him, but eventually they saw that he was that he was making progress. Typically adults are impatient when learning to play a new instrument. They do not want to put up with the frustration associated with this learning, something to which most students adapt.

Another study by Uang Zang at the University of Minnesota in Minneapolis focused on the acquisition of foreign accents in adults. When the adults were given recordings that mimicked the exaggerated baby talk of cooing mothers, the adults progressed quite rapidly.

Volunteers visiting Virginia Penhune’s lab at Concordia University in Montreal learned to press keys in a certain sequence, the adult volunteers outperformed the younger volunteers.

Juggling is a challenging ask of hand-eye coordination. Nearly 1,000 volunteers from all age groups learned to juggle over six training sessions. Although the 60 to 80-year olds started slowly, they soon caught up with the 30-year-olds. At the end of the six session all adults were juggling more confidently than the 5 to 10 year olds.

Adults also tend to hamper progress with their own perfectionism, whereas children jump onto tasks while adults are agonizing over the mechanics of movement. Adults tend to conceptualize exactly what is required. Gabriele Wulf of the University of Nevada at Las Vegas says “Adults think so much more about what they are doing. Children just copy what they see.” Wulf’s work shows that we should focus on the outcome of our actions rather than on the intricacies of movement. Similarly overly rigid practice regimes can stifle long term learning. For example, it is better to shoot around the court, rather than trying to perfect a shot from a particular position. Even if one really feels compelled to do this, they should intersperse their shooting with shots from different positions on the court.

We also may have a tendency to lose confidence as we get older, and this can have a big impact on performance. In one study half the students were given a sham test on pitching a ball in which they were told that their performance was above average. They performed better on a test than a ground that had practiced but had not been given sham feedback.

One of the big problems we adults have is finding time to learn. We work, have errands and commitments to others including our families. However, babies have all the time in the world to learn. Food, drink, even their personal hygiene is taking care of for them. Gradually some obligations develop, but some of them regard learning and they still have gobs of time to learn. When we are freed of these obligations, we adults should not forget to take advantage of this additional time to learn new things and to engage in new pursuits.

To address the short amount of time that working adults have, the cognitive scientist Ed Cooke has developed a website, that works to integrate learning into the adult day and to take some of the pain out of testing.

It is also important to remember that exercise is important and the amount of exercise can be fairly modest. (See the healthymemory blog post, “To improve your memory, build you hippocampus.”)

Why Have We Stopped Getting Smarter?

September 10, 2014

“Why Have We Stopped Getting Smarter” is the subtitle of a an article in the NewScientist August 23 2014 titled “Dumbing Down.” I feel compelled to post about this article because it is a likely sign of the ending of, or perhaps even a reversal of, the Flynn Effect. I have written several posts on the Flynn Effect (type “Flynn Effect” into the healthymemory blog search box to find them.). The Flynn Effect is the increase in IQ scores that has been occurring over the past several decades. This has required the repeated re-norming of IQ tests so that the average remains at 100. Well that increase has now stopped and might even be reversing.

The New Scientist article goes into several explanations as to why this has happened. One of them is that smarte r people are having fewer children, so that dumber people are contributing more to the average wih the result that the average IQ has stopped increasing and might even have begun to decrease.. There seems to be a belief among some that we have stopped getting smarter and might even be dumbing down, hence the title and subtitle of the article.

This is ironic because Flynn himself used the effect to argue that IQ tests were not accurately measuring intelligence. He argued that had there been true increases in intelligence, society would have advanced much more than it has, and would be in much less trouble than it is in. So I think he would also argue that the end and possible reversal of the Flynn Effect does not mean that we have stopped getting smarter or that we are dumbing down.

Knowing and believing one’s IQ score can be a problem. Those with high scores might reason that they do not need to learn or apply themselves because they are blessed with so much brain power. On the other hand, those who know and believe their low IQ scores might think that they lack sufficient brain power and concede defeat.

Of course readers of the healthymemory blog should believe that they should use whatever brain power they have to best advantage. Moreover, their goal should be to continue to learn and grow their cognitive capacity as long as they live. They should also know that neurogenesis provides for this growth as long as the maintain their physical health and grow the health of their memories by following some of the activities (there are way to many to follow them all) they find in the healthymemory blog.

© Douglas Griffith and, 2014. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and with appropriate and specific direction to the original content.

Why Our Brains Never Fill Up

September 7, 2014

The answer to this question can be found in the September/October 2012 Scientific American Mind in the article “Making New Memories.” Actually readers of the healthymemory blog should already know the answer to this question. The answer is neurogenesis. Neurogenesis is a process that does not stop when we age. It continues until we die. Now the hippocampus is one of only two sites in the adult brain were new neurons grow. They grow in the region of the hippocampus called the dentate gyrus. The rate of neurogenesis in the hippocampus is estimated to be 1400 neurons a day. This is important as the hippocampus plays a central role in memory.

There is an expression, neurons that fire together wire together. This expression captures the concept of the Canadian psychologist Donald O. Hebb’s Cell Assembly Theory. One problem has been that most cell assemblies are associated to other cell assemblies and so forth and so forth. Although this is the basis for cognitive enrichment, how are all these cell assemblies distinguished? In 1995 the psychologists James L. McClelland, Randall C. O’Reilley, and Bruce L. McNaughton proposed that the cerebral cortex forges these connections and the hippocampus tags cell assemblies so that distinct memories are filed away. But where did these new neurons come from to keep these memories distinct? At that time it was thought that we only have the neurons with which we are born. We even lose many of those neurons very early in life. It was not until the late 1990’s that neurogenesis was discovered. Subsequent research has indicated that this neurogenesis continues until we die. So these neurons are being created just when they are most needed! See the healthymemory blog post, “What is Neuroplasticity and How Does It Work.”

So key to keeping and maintaining your memory is to build a healthy hippocampus. To learn how to build your hippocampus, see the healthymemory blog post, “”To Improve Your Memory, Build Your Hippocampus.”

Growing old is no excuse for old dogs not learning new tricks. Growing old is no excuse for not continuing to learn and do new things. Cognitive decline is a myth. See the healthymemory blog post, “The Myth of Cognitive Decline.” Cognition might slow down as we age and, although there are some biological factors underlying part of this, the brain adapts. Apparent slowness and occasional forgetfulness, so called “senior moments,” are likely the result of the vast amounts of information that are stored in the elderly brain. This is especially true of the elderly brain that has spent a lifetime growing and learning. It takes more time to process and retrieve information from this enlarged network. Apparent slowness might well be due to cognitive richness rather than cognitive decline.

© Douglas Griffith and, 2014. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and with appropriate and specific direction to the original content.

The Benefits of Physical Exercise

June 5, 2014


This post is taken from Nurturing the Older Brain and Mind by Greenwald and Parasurman.  They write in the summary of their chapter on physical exercise, “Of the various experiential and lifestyle factors in cognitive aging, which they have reviewed in their book, physical exercise is probably the one whose effects are best understood.  They reviewed literature on non-human in addition to human subjects.  They write, “There is strong evidence that aerobic exercise can reduce and in some cases eliminate cognitive deficits associated with healthy aging.”    Exercise benefits neurogenesis and synaptic plasticity.  Neurotrophins also are produced as a result of exercise and mediate  the beneficial effects of exercise. They also note that there is a growing understanding of the neural mechanisms that underlie such benefits.  They note that the mechanisms appear to be centered on the dentate gyrus.   The dentate gyrus is important for the formation of new memories.

Although knowing the neural mechanisms of the benefits of exercise is good, many readers would like to know how much exercise is “enough.”  Unfortunately, there is little information on this topic.  All I can cite is a previous healthy memory blog post, “To Improve Your Memory, Build Your Hippocampus.”  In that study people benefited from walking briskly for 45 minutes three days a week for six months.  So there is evidence that that amount is sufficient.  So if you enjoy exercising, please do more, if you do not, try to do something of the order of 45 minutes a day for three days a week.  I have a hunch that any physical exercise one does is beneficial, but data regarding the minimum amount that is beneficial is woefully lacking.  It is good to do something you enjoy.  The feeling both doing and after a workout can be quite enjoyable.  Frankly, I find exercising easier than dieting and nutrition, to which we shall turn next.

© Douglas Griffith and, 2014. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and with appropriate and specific direction to the original content.

A Neurocognitive Framework for Ameliorating Cognitive Aging

May 31, 2014

This post is taken from a chapter with the same name, “Ameliorating Cognitive Aging:  A Neurocognitive Framework”  in the book Nurturing the Older Brain and Mind  by Greenwood and Parasuraman.  Brain aging needs to be dealt with.  There is cortical shrinkage and there are white matter changes.  The shrinkage and white matter changes have a small effect on cognitive performance.  Neurotransmitter  dysfunction is a matter of more concern.  Then there are genetic factors.  First of all there is the genotype, then the gene expression from this genotype.  Although some individuals suffer from a genetic predisposition to dementia, these are not deterministic, but rather predispositions.  That is, given such and such experiences or external factors, the likelihood of dementia increases.  Then there are epigenetics, which determine how the genes are actuated.  Epigenetics are affected  by lifestyle and experiential factors such that favorable factors can enhance the probability of favorable genetic readouts.

Turning to the lifestyle and experiential factors, education, exercise, diet, learning and training, and combinations of these factors enhance the likelihood of good cognitive performance throughout one’s lifespan.   More details on these individual factors will be provided in subsequent healthymemory blog posts.

Then there is the matter of neuronal plasticity that includes neurogenesis, synaptogenesis, dendritic arborization, and network reorganization.   An example of network reorganization is the greater use of both hemispheres as we age.  When I was a graduate student I was taught that our nervous system was fixed and could not be modified when damaged or was damaged to aging.  Fortunately, what I was taught as a graduate student has been found to be woefully in error.  These processes can occur well into old age.  But they need to be activated by new learning and experiences for them to occur.

Next there is cognitive plasticity.  Top-down processing strategies can be used to make better use of our accumulated knowledge.  Then there are our well-developed prefrontal lobes for effective executive functioning.

I have often written of the importance of building a cognitive reserve.  Although advice was provided as to how to build one’s cognitive reserve, Greenwood and Parasuraman have provided the first neurocognitive framework to explain how this occurs.

© Douglas Griffith and, 2014. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and with appropriate and specific direction to the original content.

REST, Epigenesis, Neuroplasticity, Cognitive Reserve, & Alzheimer’s

April 8, 2014

The March 19 Washington Post published an article written by Angela Zimm, “Fetal brain protein reactivates in old age, may fight dementia.” The research was conducted by scientists at Harvard University and published in the journal Nature. It reported that a protein called REST is depleted in the brains of people with Alzheimer’s. It was found at a level three times as high in people who did not experience dementia even when their brains had indications of the disease. According to Yanker, a professor of genetics at Harvard Medical School in Boston, “There’s a long-standing puzzle in neurology why a large percentage of the aging population when they die have enough abnormalities in the brain to classify as Alzheimer’s, though they don’t develop the dementia.”
This is a rarely publicized fact about Alzheimer’s, that there are many people who do not exhibit the symptoms of dementia even though their brains at autopsy are found to have the so-called tell tale neurofibrillary tangles and amyloid plaques. These are the only signs that allow a conclusive diagnosis of Alzheimer’s . So it appears that these tangles and plaques might be a necessary, but not a sufficient condition for Alzheimer’s disease. Most research on Alzheimer’s has been on attacking the tangles and plaques.
The only explanation that has been offered is that the people with the tangles and plaques, but not Alzheimer’s have built up a cognitive reserve to fend off this disease. Indeed, this is one of the exhortations of the healthymemory blog, to build up a cognitive reserve/. However, what has been lacking to this point is an explanation as to how this cognitive reserve is built up. The process of epigenesis is one possible mechanism for the release and maintenance of the REST protein. Possible mechanisms for building a cognitive reserve can be found in the healthymemory blog, “What is Neuroplasticity and How Does it Work”, and include, in addition to epigenesis, synaptogenesis, myleinogenesis, and neurogenesis. The healthymemory blog post, “Supporting Neuroplasticity” lists some specific practices that could aid in building a cognitive reserve.

© Douglas Griffith and, 2014. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and with appropriate and specific direction to the original content.

What is Neuroplasticity and How Does It Work?

March 15, 2014

Neuroplasticity is the ability of the brain to change its structure in response to experience.”1

What follows is a brief synopsis as to how this change is accomplished. We have an average of ten thousand connections linking an average neuron to other neurons. Given that there a hundred billion neurons, there are hundreds of trillions of synaptic linkages. Moreover there are trillions of glial cells supporting the effort. One type of glial cell is the oligodendrocyte. When we develop skills after many hours of practice the oligodendrocytes produce myelin. Mylein is a fatty sheath that coils around the neuron’s axon that sends signals to other neurons. When myelin is present, the speed of the action potential down the axon is 100 times faster. Myelin also decreases the time for recovery before the next firing, the refractory period. This refractory period is 30 times shorter. So the enhanced functoning of a myleinated circuit is 3,000 (30 times 100) faster than a non-myleinated circuit. This provides the basis for the phenomena performances we sometimes see.

Synaptogenesis is the process by which synapses are created or strengthened. Myleinogenesis the process by which these circuits become much faster. In addition to these two ways in which the brain changes as the result of experience there is neurogenesis. Neurogenesis occurs throughout the entire life span and involves the differentiation of neuro stem cells into fully mature neurons in the brain. This process may take from two to three months in contrast to the more rapid synaptogenesis that occurs within minutes to hours and becomes consolidated over days or weeks. Studies have identified this more slowly occurring neurogenesis in the hippocampal region, but it is expected that this will be found in other areas in the future. Of course, the hippocampus is important for its central role in memory. Research has also shown that physical exercise benefits hippocampal growth (see the healthymemory blog post, “To Improve Your Memory, Build Your Hippocakmpus.”)

Epigenesis is the process by which experience alters the regulation of gene expression by way of changing the various molecules (histones and methyl) on the chromosome. Understand that genes themselves are not changed. Rather the way that information is read out from the genes is changed. This is how experience and genetics interact.

SNAG is the acronym to explain how these processes result in neuroplasticity. SNAG stands for stimulating neural activation and growth. Add to this the expression that neurons that fire together , wire together. That’s how we learn, but this is also the basis for remembering. Neurons that have not fired together for a long time, can result in that memory circuit being difficult to find. The memory is likely still available, but not currently accessible. That’s why healthy memory recommends revisiting old memory circuits. When you can’t remember something, sometimes it is good not to look it up, but to keep trying to remember. Even if this attempt fails, your nonconscious mind is apt to keep looking for it, and it might suddently pop into memory hours or even days later.

Remember to use your mind to control, exercise, and grow neural circuits. This is the fundamental means of keeping a memory healthy.

1Siegel, D. J. (2012). Pocket Guide to Interpersonal Neurobiology. New York: Norton & Company. This blog post is based primarily on this reference.

© Douglas Griffith and, 2014. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and with appropriate and specific direction to the original content.

The Brain

March 11, 2014

Within the triangle of well-being (see the immediately preceding post) it is important to have some understanding of the brain, as that is the organ that the mind needs to control and grow. All of the following are estimates:1

  • There are 1 million neuronal connections formed every second.

  • There are 100 billion nerve cells in the brain.

  • It computes 100 trillion instructions per second compared to the 25 billion instruction per second done by a typical desktop computer.

  • There are 500 trillion synaptic connections in an adult human brain.

Moreover, there are trillions of glial cells providing support.

It is also important to know that neurogenesis occurs throughout the entire life span and involves the differentiation of neuro stem cells into fully mature neurons in the brain.

This brain is one tremendous device we have. Unfortunately, the brain frequently seems to have a mind of its own. And it requires dedicated focused attention for the brain to grow and fulfill its potential.

Transactive memory is a resource consisting of the memories of our fellow humans. These memories can be accessed through direct personal relationships or through technology. Technology brings us the wisdom of the ancients. It also allows us to profit from the mistakes of our predecessors.

Mindfulness and meditation help our minds control our brains including our emotions. They also develop our attentional powers so we are able to grow and achieve in desired directions.

Our brains are a terrible thing to waste. But our minds can prevent our brains from being wasted.

1Huang, G.T. (2008). Essence of thought. New Scientist, 31 May, 30-33.

© Douglas Griffith and, 2014. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and with appropriate and specific direction to the original content.


July 27, 2010

This blog post was inspired by the book, The Scientific American Brave New Brain.1 When I was a graduate student I learned that neurogenesis, the creation of neurons, might occur after birth in other species, but not in humans. Moreover, this was dogma. There was no question about it. Recent research has invalidated this dogma. Neurogenesis has been found in at least two sections of the human brain: the olfactory bulbs and the dentate gyrus of the hippocampus. The hippocampus is critically involved in learning and memory. It is difficult to underestimate the significance of this finding. Well into old-age new brain cells continue to develop. It is likely that neurogenesis occurs in other parts of the brain, but that remains to be documented.

This turns out to be sort of a good news/bad news story. Neurogenesis does occur, but these new brain cells disappear if they are not used. Moreover, it appears that simple use is not sufficient. They need to be challenged and exercised hard if they are to survive.

A reasonable question is whether we can do anything to generate new brain cells. Most of the research in this area has used animals for subjects. Rats and mice that exercise on a running wheel produce twice as many new cells than sedentary rats do. Eating anti-oxidant-rich blueberries seems to generate new neurons in the rat hippocampus as do changes in their cages or new toys.

One experiment injected rats with a drug, BrdU (bromodeoxyuridine), that marks only new cells. A week later half of the treated rats were assigned to a training program whereas the other group stayed in their home cages. Rats that successfully completed the training course retained many more newborn neurons than did the stay at home group or rats who failed to complete the training course.

So although we do not yet have proof that mental activity will either produce neurogenisis or maintain more of the cells normally produced through neurogenesis, it should not be surprising when such evidence appears. Indeed, it is reasonable to engage in these activities now. Two activities are recommended by the Healthymemory Blog to further brain health. One is the use of mnemonic techniques, which not only enhance memory performance, but also make demands on both hemispheres of the brain. Note that there is a whole category of blog posts devoted to this to topic. The other recommendation is to use technology, the internet being a prime example, to provide challenges to the brain. Blog posts on this topic can be found in the category Transactive Memory.

The conjecture offered in Brave New Brain is that in the future new cells will be generated at will, where and when you need them. How this will be done remains to be. Perhaps we shall learn how different types of cognitive activity produce neurogenesis in specific parts of the brain. Or perhaps it will be learned how brain stimulation can produce neurogenesis. The benefits of meditation are also mentioned. It is noted that exercise was not very popular in the 1950s, but has become commonplace today. Perhaps meditation will become just as popular in the future. Healthymemory Blog posts on meditation and similar restorative activities include “Restoring Attentional Resources,” More on Restoring Attentional Resources,” and “The Relaxation Response.”

1Horstman, J. (2010). San Francisco” Jossey-Bass.

© Douglas Griffith and, 2010. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and with appropriate and specific direction to the original content.