Posts Tagged ‘Hippocampus’

Suggestible You 6

March 22, 2017

“Suggestible You” is the title of a book by Erik Vance.  The subtitle is “The Curious Science of Your Brain’s Ability to Deceive, Transform, and Heal.  This post is about the placebo response and related phenomena.   This is the sixth post on this book.

This post is on nocebos.  Remember that placebo is Latin for “I shall please.”  Nocebo means “I shall harm.”  So nocebos can be thought of as negative placebos.

In 1886 a physician named John Mackenzie was treating a woman with a serious case of hay fever and asthma.  For a variety of reasons, he was not convinced that the patient’s condition was fully authentic.  For her next visit he place a rose in his office.  As soon as she sat it she had powerful allergic reaction that brought on an asthma attack.  The flower was artificial and served as the nocebo.

Cholecystokinin (CCK) is a key messenger in activating intestinal functions, including digestion and the release of gastric acid and bile.  It also plays a role in making you feel full after a good meal.  But if you inject CCK into someone, it causes anxiety and nausea and can induce panic attacks.  It also seems to increase pain by lessening the impact of internal opioids.  Fabrizio Benedetti set up an experiment with patients recovering from  minor surgery in which he gave them a drug and told them it would make their pain worse when it was actually just saline.  The patients did report more pain with the saltwater injection.  Then Benedetti blocked their brains’  CCK release with another drug.  Now the patients felt better when the CCK was blocked.  Vance wrote,”What opioids are for placebos is what CCK is for nocebos; a mechanism giving expectation power in the body.  And whereas blocking opioids killed the placebo response and made patients feel worse, blocking CCK actually supercharged pain relief by allow the brain’s internal pharmacy to run wild.”

Nocebo effects are much easier to create than placebo effects.  Negative expectations can be stronger than positive expectations.  Vance note that nocebos and placebos in the brain take two different routes.  They look similar, go to similar places, share some of the same highways, but still are totally different routes, and nocebos take all the best shortcuts.  This does make  sense, as the aversion to pain is fundamental not just to being human, but also to being alive.  Colloca notes that although the nocebo affects the same reward/expectation regions in the brain, it also includes one more that placebos do not:  fear.  The hippocampus plays a key role in the storage of memories and it also plays a key role in fear conditioning anxiety.  Brain imaging indicates that while the hippocampus is mostly absent from placebo effects, it lights up during the experience of nocebos.

Fear is at the heart of nocebos, and fear is a powerful emotion.  Fear headlines in the news elicit much stronger responses that do pleasant ones.  In 2014, even before anyone had died of Ebola in the United States, 25% of Americans were worried they or their families could contract it.  Thousands of people visited doctors claiming they had signs of the virus, and 650 of those people had symptoms serious enough for their cases to be passed on to federal officials.  As it turned out, only four people in the United States had the disease:  a visitor who got it in Liberia, two nurses who had treated him, and a doctor who had been working in an Ebola.

So we need to be careful to not let our fears get out of hand.  And let us hope that doctors make more use of nocebos in treating pain.

Memories from Infancy and Early Childhood

January 27, 2017

This post is based on Chapter 1, “I Remember Being Born” in “THE MEMORY ILLUSION” a book by the psychologist Julia Shaw, Ph.D.  Many millions of people remember being a baby.  Fewer people, but still in the millions remember being born, and even fewer people, but still in the millions remember being in the womb.  These people are wrong as “research has long established that as adults we cannot accurately retrieve memories from our infancy and early childhood.  To put it simply, the brains of babies are not yet physiologically capable of forming and storing long-term memories.  People have these misconceptions about remembering due to the creative component of memory that strives to make meaning of the world.

The estimated average age at which we can begin to form memories that last into adulthood is 3.5 years of age, but according to some such as Qi Wang of Cornell University this figure is likely to depend on the individual and can be anywhere between 2 and 5 years of age.

The parts of the brain responsible for long-term memory, including part of the frontal lobe and the hippocampus, begin to grow at around eight or nine months.  According to Harvard professor Jerome Kagan, one clue that children start to develop memory at about nine months is that this is typically when they become less willing to leave their parents.  Being able to miss their mothers is taken as a sign that the infants have a memory of their mother having just been present, and notice when she leaves.  “If you’re five months old, it’s out of sight, out of mind.  You’re less likely to cry because you just forgot that you mother was ever there, so it’s not as frightening.”

Long-term memory capabilities develop quickly as we age, both in duration and complexity.  We increasingly understand how the world around us works and what we should consider important.  The basic functions of long-term autobiographical memory are established within the first fews years of life.  But the main structures involved in memory (the hippocampus and related cognitive structures) actually continue to mature well into early adulthood.  This finding has contributed to the notion of an ‘extended adolescence’ that lasts all the way to the age of 25, since the brain continues substantial maturation until at least this age.

The baby brain  at two to four weeks of age is about 36% of the final adult volume, 72% at one year of age, and 83% of the final adult volume by two years.  By the age of 9 the brain reaches about 95% of the adult volume, and it is not until about the age of 13 that our brains reach their full adult size.

While the baby brains undergo rapid growth they also undergo massive neuronal pruning.  That is. individual neurons disappear.  This process begins almost from birth, and finishes by the time we hit puberty.  According to Maja Abitz and her team, adults actually have a whopping 41% fewer neurons than newborn babies in important parts of the brain that play a role in memory and thinking, such as the mediodorsal nucleus of the thalamus.

There is also an overproduction of synaptic connections in infancy followed by persistence of high levels of synaptic density into late childhood or adolescence.  As we enter late childhood, our brains start to become better at knowing what connections we need to keep and which are superfluous.  From there on until mid-adolescence our brains undergo a short of spring-cleaning.  So perhaps “when you were five years old you could list all of the dinosaurs, but did you really need all that information?  Probably not, says your brain and erases the connections and neurons responsible for much of this knowledge.”  “So, due to structural insufficiencies, as well as organizational and linguistic deficits, memories of early childhood events cannot last into childhood.

This research does not suggest that just because we cannot remember them, that early childhood events are unimportant.  According to a 2012 review of the long-term repercussions of adversity experience in early life by medical doctor Jack Shonkoff and his colleagues experiencing adversity, even at an age before we can consciously remember it as adult, can have lasting effects.  “Early experiences and environmental influences can leave a lasting signature of the genetic predisposition that affect emerging brain architecture and long-term health.”

To read more about the negative effects in early childhood read the healthy memory blog post,”Turning on Genes in the Brain.”  The single best predictor of the healthy growth of a baby is to ask its mother, “Did you want this child?”  In 2005 scientists at the University of Wisconsin-Madison designed a study showing what can happen to children whose parents answer “no” to this question.  The researchers studied children who were “reared in extremely aberrant social environments where they were deprived of the kind of caregiving typical for our species.”  This meant that for seven to forty-two months after their birth, the twelve girls and six boys had lived in Russian or Romanian orphanages  that the World Health Organization described as poor to appalling.  These environments were generally void of stimulation and human interaction.  The children seldom experienced the love and caring of adults who recognized and responded to their needs.These children were adopted by American families.  Within a year, most of their medical problems—ear infections and stomach problems, malnutrition and delayed growth—vanished.  Nevertheless, due to their legacy of neglect many of the children were diagnosed with attachment disorders, an inability to form emotional bonds to those closest to them

© Douglas Griffith and healthymemory.wordpress.com, 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 healthymemory.wordpress.com with appropriate and specific direction to the original content.

A High Risk But Viable Alternative to Kurzweil’s Singularity

December 7, 2016

Kurzweil’s Singularity consists of uploading the information in human biological brains into the silicon of computer hardware.  Kurzweil even regards this as possibly occurring during his own lifetime, so Kurzweil is doing everything possible to extend his life.  HM has previously indicated that this is highly unlikely because Kurzweil is ignoring the reality that silicon and biology differ.

The 29 October 2016 issue of the “New Scientist” has an article titled, “$100 million project to make intelligence-boosting implant.”  Entrepreneur Bryan Johnson launched the company Kernel earlier this year.  Johnson is working with Theodore Berger at the University of Southern California, who is looking at the hippocampus.  Healthy memory blog readers should know that the hippocampus is a key brain region involved in the retrieval of memories.  There is a hippocampus in each hemisphere, so we have two hippocampi.

Berger is working with people who already have electrical implants in their brains to treat epileptic seizures.  Instead of using these implants to stimulate the brain, his team has been harnessing them to record brain activity, to learn more about how our memory works.   Johnson says that once we know how a healthy brain functions, we should be able to mimic it.  The goal is to restore function in people with memory disorders by stimulating the same pattern of activity.  Berger has had enough success with animals that he has begun experiments with people.

Johnson says, “The idea is that if you have a loss of memory function, then you could build a prosthetic for the hippocampus that would help restore the circuitry and restore memory.”

It is both appropriate and fair that people with memory disorders will be the first to try the device.  Johnson says, “The first potential superhumans are those who have deficits to start with.”  He then plans to develop the prosthesis to enhance memory and potentially other functions in healthy people.  His vision of the future is one in which it is normal for people to walk around with chips in their brains, providing them with a cognitive boost.

Johnson has put up $100 million of his own to go on developing such a device.  It will be as tiny and easy to implant as possible, while still being able to record or stimulate multiple neurons.  The research also involved working on ways to develop rules that underly patterns of activity that dictate normal brain function for an individual.

Johnson says “If we can mimic the natural function of the brain, then I posit the question, what can’t we do?”  Could we learn a thousand times faster?  Could we choose which memories to keep and which to get rid of?  Could we have a connection with our computers?”

Note that Johnson is asking questions and not making promises.  To be sure this is high risk research, but it is one that is based on viable approach, unlike Kurzweil’s proposal.  Johnson has identified necessary first steps on the way to a marriage between the brain and silicon.

© Douglas Griffith and healthymemory.wordpress.com, 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 healthymemory.wordpress.com with appropriate and specific direction to the original content.

Computers in Our Brains

August 25, 2016

This post is based primarily on an article by Elizabeth Dworkin in the 17 April 2106 issue of the Washington Post titled “Putting a computer in your brain is no longer science fiction.”  It describe the research done by Silicon technology entrepreneur Bryan Johnson at his company Kernel, website is kernel.com.  It does not appear that Johnson has already put a computer into the brain, but rather is in the process of designing a computer to put into the brain.  The article also cites work by biomedical researcher Theodore Berger who has worked on a chip-assisted hippocampus for rats.  This work has yet to advance to humans.  And it probably will be many years before any fruits from this research will be realized.

This post is filed under transactive memory, which included posts on using external technology to build a healthy memory.  Now work is progressing on moving computer technology inside the brain.  Of course, anything that assists memory health will be welcomed.

An interesting conjecture is how this new technology would be used.  The statistics reported in the immediately preceding post made HM wonder to what extent people were making use of the biological memory they had.  It may be that when some people age their cognitive activity decreases.  And it may be that this failure to use it that is the primary cause of dementia.  This appears to be even more likely when there is evidence that people who have the defining physical features of Alzheimer’s never show any of the behavioral or cognitive symptoms.

So a reasonable question is how many people would benefit from computer implants?  It would be surprising if no one benefited, but it is not a forgone conclusion that everyone would benefit.  Some people might shut down cognitively even given a computer enhancements.  Of course, this is just a conjecture by HM.

HM would hope that people would still engage in the activities advocated by HM, to include growth mindsets, meditation, and mindfulness, in addition to general practices for personal health.

© Douglas Griffith and healthymemory.wordpress.com, 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 healthymemory.wordpress.com with appropriate and specific direction to the original content.

Neuroplasticity and Neurogenesis

June 8, 2016

Chapters 2 and 3 of Sharon Begley’s “Train Your MInd, Change Your Brain” cover neuroplasticity and neurogenesis.  Prior to discussing neuroplasticity, how learning takes place needs to be discussed.  To explain how learning takes place psychologist Donald Hebb conceived of cell assemblies.  He proposed that learning and memory were based on the strengthening of synapses.
Somehow either the neuron that fires first in the chain (the presynaptic neuron) or the neuron that fires next (the postsynaptic neuron), or both, change in such a way that the firing of the first is more likely to cause the firing of the second.  Learning and memory involve the firing of large assemblies of these cells.  Hence Hebb’s theory is called cell assembly theory.  Hebb’s maxim is that cells that fire together wire together.

Virtually all the research on neuroplasticity involved animals.  This is because surgery was almost always required. Sensory  or motor connections might be severed, and then observations would be made regarding the effects of these operations.  Sometimes connections were rewired so that animals would see sound or hear light. The late nineteenth psychologist William James had wondered , were scientists were able to alter neuron’s paths so that exciting the ear activates the visual cortex and exciting the eye the auditory cortex, we would be able to  “hear the lightning and see the thunder.”  So James was correct.  And all this research invalidated the longstanding dogma that the nervous system could not be rewired or rewire itself underscoring the reality that the nervous system can and does rewire itself.

The longstanding dogma that new neurons  could not be created, neurogenesis, was more difficult to disprove.   Before cells divide, they make a copy of their DNA.  As cells can’t conjure the double helix out of thin air, biochemicals snag the requisite ingredients from within the cell and assemble them.  One element of DNA, thymidine, lets a radioactive  molecules glom on to it.  When the thymidine becomes incorporated into the brand-new DNA, the DNA has a spot of radioactivity, which can be detected experimentally.  Old DNA does not have this glow.

Joseph Altman, a new neuroscientist at MIT, decided to try the new trick on brains.  By scanning neurons for tell tale glows he figured he would be able to detect newborn DNA, and newborn cells.  He found neurons of adult rats, cats,  and guinea pigs with thymidine—indicating that they had been born after Altman had injected them with the tracer.  He published these finding in three prestigious scientific journals in 1965, 1967, and 1970, yet his claims were ignored,   Altman was denied tenure at MIT and joined the faculty of Purdue University.

Research was done using nonhuman  animals with rich environments.  That is animals who lived in enriched environments with exercise wheels and novel features were compared to animals living in impoverished environments.  The formation and survival  of new neurons increased 15% in a part of the hippocampus called the dentate gyros, which is involved in learning and memory.

To this point humans had not been involved in the research, the reason being that noninvasive brain imaging could not address this issue.  Brains needed to be taken from   dead research participants.  Oncologists injected BrdU into cancer patients because is marks every newborn cell.  This allowed them to assess how many new cancer cells were developing.  The researchers were able to enlist the cooperation of oncologists and their patients.  After these patients succumbed to cancer, their brains could be examined to see if any new  noncancerous cells had been generated.  Thanks to these patients and their oncologists, new neurons, indicating neurogenesis, were found in the hippocampus.

An interesting find was that forced exercise does not promote neurogenesis.  The neuroscientist Gage explained to the Dalai Lama, “Running voluntarily increases neurogenesis and increases learning even in very, very old animals.  It seems like the effects of running on neurogenesis and on learning are dependent on volition.  It has to be a voluntary act.  It is not just the physical activity.

When the neuroscientist Fred Gage sat down with the Dalai Lama it was clear that new neurons arise from neural stem cells in the adult human brain, which persist and support ongoing neurogenesis.  This discovery expanded the possibilities for neuroplasticity.  The neural electrician is not restricted to working with existing wiring, he can run whole new cables through the brain.

In humans new neurons might do more than help with learning.  The hippocampus plays an important role in depression.  In many people suffering from depression, the dentate gyrus oaf the hippocampus  has drastically shrunk.  There is a question of cause and effect, whether another factor caused the hippocampus to shrink leading to depression, or whether depression caused the shrinkage.

New research suggests that people who are suffering from depression are unable to recognize novelty.  Gage said this to the Dalai Lama, “You hear this a lot with depressed people.  Things just look the same.  There is nothing exciting in life.”  “There is also evidence,” Gage said, “that if you can get someone with depression to exercise, his depression lifts.”  So neurogenesis might be the ultimate anti-depressant.  When it is impaired for any reason, the joy of seeing life with new eyes and finding surprises and novelty in the world vanishes.  But when it is restored the world is seen anew.

It is clear that chronic stress impairs neurogenesis, at least in mice.  Gage’s colleague, Peter Ericsson suspects that holds lessons for humans also.  “In lab animals, chronic stress dramatically decreases neurogenesis as well as spatial memory..  When people under stress experience severe memory problems—forgetting their way to work, going into the kitchen and then no remembering why they went in—it is likely that what they’re experiencing is the very negative of stress on the function of the hippocampus due to decreased neurogenesis.”

Can You Remember Things that Never Happened?

March 24, 2016

This post is based largely on portions of the fourth chapter in Elixir J. Sternberg’s Book “Neurologic and the Brain’s idea Rationale Behind Our Irrational Behavior.” The title of this post is the same as the title of Chapter 4.  Regular readers of the health memory blog should know the answer to the question posed in the title.  The answer is “yes.”  Elizabeth Loftus and others have done extensive research in this area.  They have a variety of methodologies for implanting false memories so that they are definitely believed.  I saw an example of one of these experiments on the PBS program NOVA.  In this case the research participants were convinced of a crime that they never had committed.  To find previous posts on this topic enter “Loftus” into the search block of the healthy memory blog.

Sternberg begins the chapter with a quote from Gabriel Garcia Marquez that largely captures the workings of our memories.  “He was still too young to know that the heart’s memory eliminates the bad and magnifies the good, and that thanks to artifice we manage to endure the burden of the past.”

A research group in Israel filmed a young woman, with no history of memory problems for two days straight.  Except for the cameras they were ordinary days.  At various intervals over the next few years she filled out questionnaires that tested her memories of those days.  The researchers used fMRI while she was filling out these questionnaires.  Over time the more distorted her memory became for the details.  What was especially interesting was how her brain activity changed over time while filling out the recall questionnaires.  As time passed and the memory errors accumulated, her memory appeared to be less endless reliant on the activity of the hippocampus.  The fMRI revealed reduced activation there as her recollection became more distant.  Other regions of the brain, including the medial prefrontal cortex and associated regions, became more and more active.  The medial prefrontal cortex is associated with self-centered thinking.  Her memory was accessing not simply a record from a neurological file, but a representation stored across multiple systems.  Her memory drifted away from accurately recording the details of that time period and instead became focused on her.

“To a large extent, our memories define us.  Our personal history forges our self-image and assembles our store of knowledge.  When the unconscious system in the brain encodes our memories, it is shaping who we are.  It doesn’t record our experiences impartially as a video camera would, because it focuses on our role in the story, on the aspects that we care about.   At any given moment, there is a context of how we are feeling, our emotions at that instant, what we are expecting or dreading, and what that moment means to us.  It is on that basis that the brain begins to compose its first draft.”

Three years after 9/11, two groups of New York City residents were enrolled in an experiment to learn how their emotions at the time of the attacks might have affected their memory.  The first group of people who were in downtown Manhattan that day close to the World Trade Center, and who personally witnessed the events of that day,  The second group consisted of people who were in midtown several miles away.  As would be expected, the downtown group rated their memories as being more vivid, more complete, and more emotional instances that the midtown group did.  And they had more confidence in the accuracy of their memories, but the neurological results revealed a different story.

The hippocampus is the area key to episodic memory, of which recalling 9/11 is a conspicuous example, but depending on the type of memory being accessed, other areas of the brain may be recruited to varying degrees.  For example, the amygdala may be activated when the memory is of an emotional nature, and the posterior parahippocampal cortex will become more involved when the brain attempts to access the more meticulous spatial details surrounding the event.  The members of the midtown group showed activation of the posterior  parahippocampal cortex as they recalled the details of 9/11, but only trivial amygdala activity.  It was just the opposite for the downtown group.  They exhibited striking activity in the amygdala but not in the posterior parahippocampal cortex.  This neuroimaging suggests that the downtown group recalled the events of the day for their emotional impact at the expense of remembering peripheral details.  Studies have revealed that the more emotionally  affected people are in recalling 9/11, the better they are at consistently describing the central events of what happened to them that day, but the worse they are at providing reliable description of the emotionally  neutral details.

There is a technical difference between telling a lie and confabulation.  A person telling a lie knows that he is telling a lie.  However, a person confabulating is trying to make a coherent story where substantial memory loss has occurred.  The chapter begins and ends with a man with both severe mental and addiction problems and a faulty memory.  He continually tries to put together a coherent story from the scraps of memory he can access, because he does not want to admit that he does not know.  Although his is a clinical case, we all work to make coherent stories from what memories we can find.  The unconscious system takes a self-centered egocentric approach to construct good narratives.

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 healthymemory.wordpress.com, 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 healthymemory.wordpress.com with appropriate and specific direction to the original content.

The Hippocampus: Key to the Future of Human Memory

February 13, 2016

As I was perusing “The Scientific American BRAVE NEW BRAIN”  by Judith Horstman  I came across a page titled “An Artificial Hippocampus.”  This caused me to speculate about an artificial hippocampus.  Actually each of us has two hippocampi, as there is one hippocampus in each hemisphere.  The importance of these hippocampi was noticed as the result of surgery done on an epileptic patient to protect him from the violent seizures he was having.  The surgery removed most of both his hippocampi, which prevented him from storing any new memories.

I have my own personal story regarding defective hippocampi.  It occurred during the later stage of my Mom’s dementia.  I would visit her and fortunately she remembered me and was glad to see me.  However, if an attendant took her to the bathroom when she returned she acted as if I had just arrived.  Clearly both her hippocampi were shot.

As the hippocampus is required for the storage of new memories, it clearly is key to he future of human memory.  Effectively functioning artificial hippocampi would provide the vehicle for storing new memories, for new learning.

We have yet to develop an artificial hippocampus that works.  I believe preliminary work is being done with animals.  Researchers are recording from the hippocampi of these animals as they learn new tasks.  Then they will try to transfer these recordings to the hippocampi of new naive animals who have not learned the task to see if they can use these recordings to perform these new tasks.  I don’t know if any successful trials have been run.  But this is exactly the type of research that needs to be done before an artificial hippocampus can be developed.  I believe that the course of this research will necessarily take a long time.

If an artificial hippocampus is developed, we know that this is a necessary structure for the storage of new memories.  However, we cannot be sure that the hippocampus alone is a sufficient solution.  There may be more to the storage of new memories of which we are unaware.

© Douglas Griffith and healthymemory.wordpress.com, 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 healthymemory.wordpress.com with appropriate and specific direction to the original content.

Cognitive Shields Protecting Against Dementia

April 22, 2015

This post is based largely on “Cognitive Shields” by Andrew Merluzzi in the .  Psychological Science Observer (February 2015, 21-28).   There have been many previous Healthymemory blog posts about autopsies of people who have exhibited no symptoms of Alzheimer’s while alive, but who nevertheless have the so-called amyloid plaques and neurofibrillary tangles which provide the definitive basis for diagnosing the disease.  Now I have a percentage to place on this statement.  About a third of post-mortem brains with the telltale features of dementia—protein tangles or miniature strokes-came from people who never exhibited symptoms during life.

The explanation that has been offered for this is that certain individuals might build buffers over their lifetimes called cognitive reserve.  This post provides information on research on the cognitive shields that build this cognitive reserve.  Actively engaging the brain can boost older adult’s recall power.  One experiment randomly more than 200 adults (ages 60-90) to engage in a particular type of activity for 15 hours a week over the course of three months.  Some activities required significant cognitive investment such as digital photography or quilting.  The other participants engaged in more leisurely activities such as listening to classical music or completing word puzzles.  At the end of the experiment participants who engaged in digital photography or quilting showed a significant improvement in memory compared to the leisurely activity participants.

Another experiment  recruited 16 older adults to play a video game called “Neuroracer.”   Participants attempted to drive a car down a virtual road, keeping constant speed and lane position.  As they were doing this they also had to pay attention to sporadically appearing shapes, pressing a button whenever they observed a green circle.  The game became more difficult as performance improved.  The comparison group played an easier version of the game where they had to drive or pay attention to shapes, but not simultaneously.  The group who played the more difficult version of the game scored better on unrelated cognitive tests. Brain imaging with an EEG revealed noticeable differences at the neural level.  Participants who played the difficult version of the game  showed more coherent activation patterns in cognitive control networks including the prefrontal cortex.  These cognitive gains were still apparent six months later.

Physical exercise is also important as it increases the flow of oxygen to the brain.  See the healthy memory blog post “To Improve Your Memory, Build Your Hippocampus” (use the healthy memory blog search box).

Another study investigated whether exercise can induce neuroprotective effects for people who have a genetic risk for Alzheimer’s.  One hundred older adults many who carried the APOE gene which increases the risk of Alzheimer’s were studied.  The participants explained their normal exercise habits and had their brains scanned twice over a period of 18 months.  It was found that exercise was critically important for the at risk group with the APOE gene.  People with this gene who didn’t exercise exhibited a 3% decrease in hippocampal volume over time.  Those carrying the gene who did incorporate exercise into their lives—more than 15 minutes of moderate exercise at least three days a week—didn’t show any decreases in hippocampal volume.  The conjectures for this result are that staying active might reduce inflammation in the brain and promote neural growth in the hippocampus building  up cognitive and brain reserve.

Research has also found that bilingual older adults have more robust white matter then monolingual adults.  This suggests that the myelin on axons in these her bundles is more intact, which would help  to buffer against age-related changes in the size and structure of the brain.  Sone also argue that it might never be too late to learn another language.  But this does take commitment.

There are many more healthy memory blog posts on the cognitive reserve and the benefits of both cognitive and physical exercise.  It is important that this information be disseminated.  People should know that they need not be passive victims of dementia, nor should they wait for a medical treatment or vaccine to treat or prevent Alzheimer’s.  To a large exert we control our own fates and should take action.

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 healthymemory.wordpress.com, 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 healthymemory.wordpress.com 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 healthymemory.wordpress.com, 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 healthymemory.wordpress.com with appropriate and specific direction to the original content.

Memory and Endurance

January 14, 2013

Diane Van Deren is one of the world’s elite ultra runners. She has run more than 1500 kilometers over 22 days. Note that that is kilometers, not meters. She has run for as long as 20 hours in a single day. When she is asked to estimate the amount of time she has been running she has underestimated her time by as much as 8 hours.

Her incredible endurance needs to be understood in the context of her memory. She, like the individuals in the immediately preceding post on Memory and Obesity, has had brain surgery to treat epilepsy.1 This surgery undoubtedly involved areas of the brain affecting the transfer of information into long term memory, such as the hippocampus.

It is hoped that this surgery effectively dealt with her epilepsy. It did have the benefit of letting her get into a more zen-like state that lets her run for longer without feeling so much strain, but the loss of the ability to retain new information is an unfortunate trade.

1De Lante, C. (2012). Stuck in the Present. New Scientist, 6 October, p.41.

Social Intuition and Social Context

April 18, 2012

Social intuition is one of the dimensions of Davidson’s Six Dimensions of Emotional Style1 (See the Healthymemory Blog post “The Six Dimensons of Emotional Style”). The two immediately preceding blog posts have discussed the Outlook and Reslience dimensions. Social intuition refers to how attuned individuals are to social signals and to their ability to pick up social cues. People with autism are at the pathological end of this dimension. Others are deficient in their social interactions being mildly puzzled by the behaviors of others. People high in social intuition can read others like a book.

The brain structures most relevant to social intuition are the fusiform gyrus and the amygdala. High levels of activity in the fusiform gyrus and low to moderate levels in the amygdala are typical of people who are moderate to highly socially intuitive. Low levels of activity in the fusiform gyrus and high levels of activity in the amygdala characterize people who are puzzled by social interactions. Studies of the autistic brain have confirmed this heightened level of activity.

Social context is similar to social intuition with these two differences. Social context refers to how one responds to the what is present and happening in the environment in general. It also involves a different brain structure. The brain structure central to social context is the hippocampus. The hippocampus should be familiar to readers of the Healthymemory blog due to its importance in memory (try entering “hippocampus” into the search box and see how many hits you get). Post Traumatic Stress Disorder (PTSD) can be regarded as a disorder of disrupted context. Studies have shown PTSD is associated with losses in the volume of the hippocampus. This diminished hippocampus has difficulty forming memories of the context in which something occurred thus conflating the dangers of a war zone with the relatively safety of home. Davidson has concluded that unusually low levels of activity in the hippocampus underlies the “tuned out” end of the sensitivity to context dimension. At the tuned in extreme high levels of activity in the hippocampus can lead to too much focus on context can make one overly self-conscious and socially inhibited. It can also lead to an obsessive need to please other people. At the other end of the continuum, too little activation of the hippocampus can lead to a lack of focus on context that might cause one to overlook something that is important or even dangerous. So Sensitivity to Social Context is another “Goldilocks” variable. Too much or too little can be bad. It needs to be “Just Right.”

Connections between the hippocampus and other brain regions, particularly the prefrontal cortex are also important. The hippocampus needs to communicate with the executive functions in the prefrontal cortex and well as memories held in long term storage. Stronger connections increase sensitivity to context. Weaker connections decrease sensitivity to social context.

Later posts will indicate how you change where you are on these social dimensions.

1Davidson, R.J. & Begley, S. (2112). The Emotional Life of Your Brain. New York: Hudson Street Press.

What is the Analogy Between Mental and Physical Exercise?

March 28, 2012

There is a clear analogy between mental, or cognitive, exercise and physical exercise. Athletes will engage in mental exercise that benefits their physical performance. So ice skaters and gymnasts will mentally rehearse their routines. Divers will run through their dives in their mind. Batters might imagine hitting that hanging curve ball out of the park. Physical exercise can enlarge your hippocampus (See the Healthymemory Blog Post, “To Improve Your Memory, Build Your Hippocampus”. The mental demands of memorizing and navigating all the streets of London enlarges the hippocampus of apprentice London cab drivers preparing for their licensing exam.

So both cognitive and physical exercise assist in keeping and enhancing a healthy memory. A modern society provides many devices that keep us from doing physical exercise, so some people decide to by pass these devices and walk to the store and climb the stairs to derive the benefits of physical exercise.

Similarly, there are many devices that help us avoid cognitive exercise. Spell checkers were discussed in the immediately preceding blog post. But we can rely on digital devices to relieve our memories of needing to remember phone numbers, addresses, or appointments. We can look up information as needed on the internet. So our cognitive demands have been reduced substantially analogous to our physical demands.

So why not consider eschewing some of this technology to afford cognitive exercise similar to taking the stairs rather than the elevator, or walking rather than driving to some destination? Use your personal memory rather than transactive memory. You will find a host of techniques for remembering information under the Healthymemory Blog category “Mnemonic Techniques.” There are also free websites to help you master these techniques see

http://www.neuromod.org/ and http://www.thememorypage.net/. Still, for very important appointments I recommend that you use transactive memory as a backup and either write it down or enter it into your digital device! (See the Healthymemory Blog post, “An Embarrassing Failure of Transactive Memory,” and “Another Embarrassing Failure of Transactive Memory)

© Douglas Griffith and healthymemory.wordpress.com, 2012. 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 healthymemory.wordpress.com with appropriate and specific direction to the original content.

Age-Proof Your Brain

February 15, 2012

Age-Proof Your Brain: 10 Easy Ways to Keep Your Mind Fit Forever is a recent article in AARP The Magazine.1 Articles like this are summarized periodically in the healthymemory blog. There are many, many things you can do to age proof your brain, but articles like these are helpful in suggesting a manageable handful from which to choose (“31 Ways to Get Smarter in 2012” was a similar posting earlier this year). Some of the ways presented in the AARP article do not readily fall into specific healthymemory blog categories, although most have been mentioned in passing in healthymemory blog posts.

Finding your purpose is a general recommendation strongly endorsed by the healthymemory blog. The AARP article cites a study done at the Rush University Medical Center of more than 950 older adults. The study ran for seven years and it was found that participants who approached life with clear intentions and goals at the start of the study were less likely to develop Alzheimer’s disease over the following seven years.

Maintaining a healthy lifestyle is implicit, but not usually specifically mentioned in healthymemory blog posts. It is important to Reduce your risks. Chronic health conditions, such as diabetes, obesity, and hypertension are associated with dementia. Diabetes approximately doubles the risk of Alzheimer’s and other forms of dementia. So it is important to follow doctor’s orders regarding diet, exercise and taking prescribed medications on schedule.

It is important to Check for vitamin deficiences. Vitamin deficiences, especially vitamin B12 can also affect brain vitality. Research from Rush University Medical Center found that older adults at risk of vitamin B12 deficiencies, had smaller brains and scored lowest on tests measuring thinking, reasoning and memory.

Diet is another topic discussed infrequently in the healthymemory blog, but as the AARP article notes “Your brain enjoys spices as much as your taste buds do. Herbs and spices such as black pepper, cinnamon, oregano, basil, parsley, ginger and vanilla are high in antioxidants.” Antioxidants are important to brain health. Curcumin, an active ingredient in turmeric is common in Indian curries. Indians have a lower incidence of Alzheimer’s. One theory is that curcumin bonds to amyloid plaques that accumulate in the brains of people with Alzheimer’s. Animal studies have shown that curcumin reduces amyloid plaques and lowers inflammation levels. A study with humans found that people who ate curried foods often had higher scores on standard cognitive tests.

Another diet recommendation is to Eat like a Greek. The Mediterranean Diet rich in fish, vegetables, fruit, nuts, and beans reduced Alzheimer’s risk by 34 to 48 percent in a study done by Columbia University. Omega-3 fatty acids in fish are important in heart health and are suspected of also being important for brain health. Generally speaking, what is healthy for the heart is healthy for the brain.

Exercise is another activity that is good for both heart and brain. According to the AARP article, higher exercise levels can reduce dementia risk by 30 to 40 percent compared to low activity levels. People who exercise regularly also tend to have better cognition and memory than inactive people. Exercise helps your hippocampi, subdcortical memory structures well known to readers of the healthymemory blog (See the Healthymemory Blog post, “To Improve Your Memory, Build Your Hippocampus, and do a search using the term “Hippocampus”.) Experts recommend 150 minutes a week of moderate activity, although as little as 15 minutes of exercise three times a week can be helpful. So Get moving.

And Pump some iron. Older women participating in a yearlong weight-training program did 13 percent better on tests of cognitive function that did a group of women who did balance and toning exercises. According to Tereas Liu-Ambrose, “Resistance training may increase the levels of growth factors in the brain such as IGFI, which nourish and protect nerve cells.”

Say “Omm” refers to meditation. Meditation techniques can usually be found under the healthymemory blog post category “Mnemonic Techniques.” The AARP article discusses a study of mindfulness-based stress reduction (MBSR). MBSR involves focusing one’s attention on sensations, feelings, and states of mindfulness. This has been shown to reduce harmful stress hormones. At the end of an eight week study MRI scans of participants’ brains showed that the density of gray matter in the hippocampus increased significantly in the MBSR group, compared to a control group. Studies have found that other types of meditation have also been beneficial. Search the healthymemory blog on “meditation” to find related healthymemory blog posts.

The remaining two recommendations fall under the healthymemory blog category “Ttansactive Memory.” Get a (social) life means interact with your fellow human beings for a healthy memory. The AARP articles mentions a University of Michigan Study in which research participants did better on tests of short-term memory after just 10 minutes of conversation with another person. There are two types of transactive memory. One type refers to the memories of our fellow humans, and the practice of seeking them out and swapping information between our swapping memories is beneficial.

Seek out new skills can involve both types of transactive memory: human and technological. So learning new things from our fellow humans, as well as from periodicals, books, and the internet is beneficial to our brains and our memories. The important point is to continue to grow cognitively and to not just do things that you routinely do.

1http://www.aarp.org/health/brain-health/info-01-2012/boost-brain-health.html

Happy Holidays from Healthymemory Blog!

December 24, 2011

The Healthymemory Blog will be taking a brief hiatus until 2012. Although there will be no new posts until 2012, there are 258 posts for your perusal. As its name implies, the Healthymemory Blog is devoted to the promotion of healthy memories. Posts are divided into three categories:

Human memory includes relevant posts regarding how memory works, its strengths and failures, as well as factors and practices that benefit memory.

Mnemonic techniques includes relevant posts on techniques that not only improve recall, but also provide beneficial brain and cognitive exercise.

Transactive memory includes posts on how to interact with fellow humans and to best use technology to promote cognitive growth.

The overall objective is to promote cognitive health throughout our lives, and not to just reduce or stop cognitive decline, but to continue to grow mentally as we age.

How Using Mnemonic Techniques Exercises the Brain

December 18, 2011

The Healthymemory Blog has a category labeled “Mnemonic Techniques.” Not all of the posts in this category are strictly speaking mnemonic techniques. Posts on specific activities you can do to foster a healthy memory, meditation, for example, are also included here. But the mnemonic techniques specific to remembering specific items of information are touted as being doubly beneficial as they not only directly improve memory, but they also provide good mental exercise for the brain. Today’s post elaborates on how the different parts of the brain are exercised.

The first action that needs to be taken on information that you want to remember is to pay attention. Paying attention involves using working memory. This involves the dorsolateral prefrontal cortex. Maintaining information here requires glucose metabolism. The initially encoding is done in the hippocampi (there is one hippocampus in each of the two brain hemispheres) from which it is distributed throughout the rest of the brain. This distribution is needed to determine the meaning, or lack of meaning, of this information. Where there is meaning, this meaning is used to elaborate the meaning by relating it to other associations in the associative cortex. When there is little or no meaning, then the mnemonic provides a means of making the apparently meaningless information meaningful. This involves recoding, which involves the dorsolateral prefrontal cortex activating other associations found in the associative cortex. Often the technique involves the formation of a visual image which activates associative networks in both cerebral hemispheres via transmissions across the corpus callosum. There is no central memory center in the brain. Rather information is stored throughout the brain. Sensory information in the sensory portions, motor information in the motor portions, and verbal and semantic information is the associative portions. Information that you know well likely has many many links to other items of information, the job of the mnemonic technique is to establish solid new links to this new information you want to remember.

Mnemonic techniques require you to pay attention. Paying attention increases the glucose metabolism to the brain. This, in turn, activates the all important hippocampi and activates memory pathways throughout the associative and sensory cortices of the brain.

Click on the Category “Mnemonic Techniques” and you find a comprehensive listing of mnemonic techniques along with descriptions of the techniques and exercises. Try starting at the bottom of the category and proceeding up. There is a specific Healthymemory Blog post, “Memory Course”, which suggests an order in which the mnemonic techniques should be approached.

There are also some websites for learning and developing proficiency in mnemonic techniques. One is www.NeuroMod.org. Click on the Human Memory Site. Then click on the “read more” link under your preferred language. You can open up an account and record and track your progress. Another site is www.Thememorypage.net. Both of these websites are free.

© Douglas Griffith and healthymemory.wordpress.com, 2011. 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 healthymemory.wordpress.com with appropriate and specific direction to the original content.

Review of The Washington Post’s The Aging Brain

December 7, 2011

This piece1 is informative and offers some good advice, but is woefully deficient in some areas that should have been included. The article is basically an annotated diagram that begins with the first step of the eye seeing something. The second step is the information arriving at the visual cortex that identifies what the eyes see. The third step is the information flowing through the associative cortex to develop further understanding. The fourth step is the information arriving at the hippocampus (actually it should be hippocampi as there is one hippocampus in each hemisphere of the brain. Information must be processed by these hippocampi if it is to be recalled later. People who have lost their hippocampi via surgery, accidents, or dementia, are unable to learn/remember new information. But it is the prefrontal cortext decides whether this new information warrants processing by the hippocampi for later use. The prefrontal cortex is an important part of the brain as it not only decides what is worth remembering, but it is involved in all the decisions we make and is responsible for regulating our behavior. Unfortunately, it is late maturing (not until our twenties) and early to decline (sometime after age 50). So far this description is accurate and it is understood that there would be similar, but not identical stages of processing for other modalities of information.

There is another section of the article on how to slow the effects of aging that provides the following advice:

Calm Down – this is good advice as the piece correctly states that stress can destroy synapses , it fouls up the hippocampus and the prefrontal cortex. It does not mention that the various types of meditation are beneficial in helping us to calm down.

Exercise – this is good advice as the increased blood flow and oxygen uptake it engenders is beneficial to the brain.

Make friends – more good advice. There have been a number of Healthymemory Blog Post extolling the benefits of socialization.

Sleep well – more good advice. Getting adequate sleep is important not only to general health, but is also critical to important brain and memory processes.

Ask about estrogen – Ladies, you can judge this one for yourselves. This recommendation is based on one study. Given the somewhat uneven results from estrogen therapies, some skepticism might be in order.

Do what you do best – Although it is true that expertise is maintained well into old age and that you are less likely to lose what you know well, it is a somewhat misleading strategy for slowing the effects of aging. Although it is fine to continuing growing in your area of expertise, it would be a mistake not to expand into some new areas. Research has indicated that maintaining brain and cognitive health should not be a reactive, defensive matter, but rather a proactive effort to continue growing cognitive competence.

An interesting question to ask, is why does the prefrontal cortex start to decline after age 50? Is it solely a matter of aging? There is the Dumbledore Hypothesis regarding the effects of aging on the brain (See the Healthymemory Blog posts, “More on Attention and Cognitive Control,”, “Passing 65,” and “Memory and Aging.). This hypothesis fits well with the Two System View of Cognition (see the Healthymemory Blog post “The Two System View of Cognition.”). According to this view, there are two primary means of processing information. System One is fast and automatic. It is the result of prior learning. This is the system that is doing the majority of the processing when we converse, drive a car, etc. System Two is slow, effortful, and demands attention. This is what is at work when we are trying to learning something new, to solve a math problem, or recognize something that is illogical or contradictory in what the person we are conversing with has said (or in our own conversation if we recognize something illogical or contradictory in what we have said. According to the Dumbledore Hypothesis as we age we increasingly rely on System One processing because we have learned much and don’t need to do as much processing as a younger person who does not have such a wealth of experience to draw upon. The problem is that since we do less System Two processing we use our prefrontal cortex less. The use it or lose it advice that we know from physical exercise also applies to cognitive exercise. When we use our prefrontal cortex more glucose is sent there. So the loss in the functioning in the prefrontal cortex might not be solely do to aging. It might be in part, perhaps in large part, to a loss in the frequency of its use.

So the new idea is to challenge our minds and to continue to learn new things as we age. (See the Healthymemory Blog post, “A Quote Worth Pondering.”) It is not too late to learn a new language, or new subject matter. These activities will engage the prefrontal cortex. Mnemonic techniques have the benefit of not only being a technique that enhances memory, but are also means of providing cognitive exercise that exercises the prefrontal cortex and activates both cortices of the brain. So aging should not cause us to be reactive and defensive, but we should go on offense, be proactive, and continue to grow cognitively.

1Berkowitz, B. & Cuadra, C. (2011). The Aging Brain in The Washington Post Health & Science Section, E1, 6 December.

© Douglas Griffith and healthymemory.wordpress.com, 2011. 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 healthymemory.wordpress.com with appropriate and specific direction to the original content.

Memory and Its Underlying Brain Structures

December 4, 2011

A variety of Healthymemory Blog posts have discussed the various brain structures underlying memory. As a book1 I have been reading has provided a succinct overview describing the interacting structures and areas of the brain that are responsible for memory I have decided to write the following post.

The initially encoding is done in the hippocampi (there is one hippocampus in each of the two brain hemispheres) from which it is distributed throughout the rest of the brain. This distribution is needed to determine the meaning, or lack of meaning, of this information. This takes place in short term or working memory. Meaningless information is quickly lost without further processing. Even the current instance of meaningful information will be lost without further processing (for example I need to meet Fred for lunch or I need to remember this for the examination). This working memory is maintained in an active mental state within the dorsolateral prefrontal cortex of the frontal lobes. Maintaining information here requires glucose metabolism.

This glucose metabolism is the physiological indication of paying attention. So when you are performing a task that requires you to pay attention, glucose metabolism is required. It is interesting to note that as you become more proficient in performing the task, the rate of glucose metabolism actually decreases. This indicates that you need to pay less attention due to your increase in proficiency.

The successful storing of information in long term memory via the hippocampi requires the establishing of links to other items in long term memory. Mnemonic techniques are developed to make what appears to be inherently meaningless into something meaningful so it can be linked to other items I long term memory for later retrieval. There is no central memory center in the brain. Rather information is stored throughout the brain. Sensory information in the sensory portions, motor information in the motor portions, and verbal and semantic information is the associative portions. Information that you know well likely has many many links to other items of information. Some memory theorists have likened human memory to a hologram. Holograms differ from photographs in that the entire image can be reconstructed from portions of the hologram. So if you break a hologram into two pieces, the entire hologram can be reconstructed from either piece, but the resulting image will be less distinct.

Memory theorists make a distinction between information being available in memory and information being accessible in memory. Information that can be readily retrieved is said to be accessible. However, if you cannot retrieve something at a given time, it is likely that that information is still not available in memory, but it is still accessible. Moreover, even after you have consciously given up trying to recall this information, it sometimes happens that at a later point in time when you are consciously thinking about something else, that this apparently lost memory pops into consciousness.

So how does this relate to maintaining and growing a healthy memory? Engaging in activities requiring significant amounts of attention increase the metabolic activity going to your working memory. This metabolic activity will decrease as you become more proficient in the activity. In many respects this is analogous to the effects of physical activity on cardiopulmonary activity. It should be noted that this practice effect is the result of transferring information to long term memory so less attention is required.

To maintain and grow long term memory developing new associative pathways throughout the brain is required. This will not be done by simply surfing the internet (which is primarily a working memory exercise). Long term memory growth is a matter of pursuing knowledge and skill in more depth to develop and strengthen associative pathways so that they are more resistant to forgetting. In other words, increasing the accessibility of the information. The very act of retrieving information is beneficial even if your initial retrieval attempts are unsuccessful. The searching for information activates memory pathways, some of which might have been long inactive. The memory search can reactivate them. Moreover, your memory will likely continuing working even after you have consciously given up the attempt.

1Restak, R., (2009). Think Smart: A Neuroscientist’s Prescription for Improving Brain Performance. New York: Riverhead Books.

© Douglas Griffith and healthymemory.wordpress.com, 2011. 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 healthymemory.wordpress.com with appropriate and specific direction to the original content.

To Improve Your Memory, Build Your Hippocampus

April 24, 2011

A previous post, “If You Do Not Like Mnemonic Techniques, Try Walking”, was a little thin given the importance of the topic. So I’ve gone to the original article1. The hippocampus is a component of the brain that is critical to memory function. Unfortunately, the hippocampus shrinks 1-2% annually in older adults without dementia, and this loss of volume increases the risk of developing cognitive impairment. This experiment was undertaken to assess whether exercise and what kind of exercise might mitigate this decline.

Participants between the ages of 55 and 80 years old were recruited, who did not have any pertinent diseases or disabilities. 120 participants were randomly assigned: half to a stretching and resistance training control group, and half to an aerobic walking group. Sessions for each group were held three times a week and lasted roughly one hour. Participants in the aerobic group started walking for ten minutes the first week and increased walking durations by five minute increments until a duration of 40 minutes was reached by week seven. Each session began and ended with approximately 5 minutes of stretching. The control group engaged in four muscle-toning exercises using dumbbells or resistance bands, two exercises designed to improve balance, one yoga sequence and one exercise of their choice. The program lasted for one year. MRIs, fitness, and short term memory were assessed before the program began, 6 months into the program, and at the end of the one-year program. Blood samples were taken at the beginning and end of the program.

Aerobic exercise (walking) increased hippocampal volume by 2%. This increase effectively reverses the expected age-related loss by 1 to 2 years. Moreover, increased hippocampal volume was positively correlated with improvements in short term memory performance. Increased hippocampal volume was also associated with greater levels of serum Brain-derived neurotrophic factor (BDNF), which helps support the survival of existing neurons and encourages the growth and differentiation of new neurons and synapses.

Hippocampal volume did decrease in the control group, but higher preintervention fitness partially attenuated the decline. The control group also exhibited improvement in short term memory performance.

Changes in fitness are associated with increased hippocampal volume. The aerobic exercise group showed a 7.78% improvement in maximal oxygen consumption (VO2) after intervention, whereas the stretching control group showed a 1/11% in VO2 max.

So although both exercise regimes were beneficial, the aerobic regime appeared to be more beneficial, especially with respect to its beneficial effects on hippocampal volume. Given the importance of the hippocampus to brain and memory, this finding is extremely important. Moreover, this aerobic exercise regimen was fairly mild and undemanding.

1Erickson, K.I., Voss, M.W., Prakash, R.S., Basak, C., Szabo, A., Chaddock, L., Kim, J.S., Heo, S., White, S.M., Wojcicki, T.R., Malley, E., Viera, V.J., Martin, S.A., Pence, B.D., Woods, J.A., McAuley, E., & Kramer, A.F. (2011). Exercise Training Increases Size of Hippocampus and Improves Memory. PNAS Early Edition, www.pnas.org/cgi/doi/10.1073/pnas.10159550108.

Take a Nap: Sleep is Important for a Healthy Memory

December 5, 2010

A recent article1 in the SharpBrains blog relates a study by Matthew Walker presented at this year’s American Association for the Advancement of Science (AAAS) convention. Young adults were separated into two groups: one that napped and one that didn’t. At noon, both groups performed a learning task. At 2 PM the napping group took a 90 minute nap while the other group remained awake. Then both groups performed more learning tasks. The group that had napped performed better than the group that remained awake.

Readers of the Healthymemory Blog should be familiar with the role of the hippocampus. The hippocampus is critical for learning. These researchers interpreted their findings as supporting the notion that a function of sleep is to clear away all the clutter stored in the hippocampus to make room for new information. Walker said “Sleep is critical to learning. It’s like the brain is a sponge. Sleep wrings certain key regions out so you’re able to soak up new information the next day. It’s as though the e-mail box in your hippocampus is full and, until you sleep and clear out those fact e-mails, you’re not going to receive any more mail. It’s just going to bounce until you sleep and move it to another folder.

We spend about one-third of our lives sleeping. So sleep must serve some important functions. There is much theory and conjecture regarding why we sleep, but experiments such as this one provide empirical evidence. It is well established that sleep is good for you. Getting the appropriate amount of sleep is tied to a better immune system, metabolic control, memory, learning, and emotional functioning.

It is said that pulling an all-nighter the night before an exam can decrease the ability to remember information by about 40 percent. Personally, I worked my way through the entire educational system receiving a Ph.D and I never pulled an all-nighter.

As we get older, we tend to sleep less. Learning proficiency also declines. Walker is interested in investigating whether there is a cause and effect relationship here. It is also interesting to speculate regarding the direction of any cause and effect. If we continue to learn and remain mentally active as we age, will our sleep increase proportionately. Perhaps this observed relationship is due to disengaging from life and new experiences when we age, which results in reduced sleep and perhaps even neurogenerative decline. Remaining mentally active, as advocated by the Healthy Memory Blog, might reduce or eliminate this decline.

1http://www.sharpbrains.com/blog/2010/10/18/take-that-nap-it-may-boost-your-learning.

© Douglas Griffith and healthymemory.wordpress.com, 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 healthymemory.wordpress.com with appropriate and specific direction to the original content.

Stroke: Then, Now, and Tomorrow

August 11, 2010

This blog post is another in the series inspired by the book, The Scientific American Brave New Brain.1 That book presents a table contrasting the way the brain once was regarded, the way it is presently regarded and some conjectures about what tomorrow might hold. Formerly stroke damage was regarded as mostly irreversible. It was believed that if improvement was not seen after several months, it would never be seen. Unfortunately, this prognosis was dictated by the then current view of the brain, that brain cells cannot be replaced when they die and that the brain is hardwired and cannot be changed. The debunking of these views was covered in the preceding blog posts, “Neurogenesis,” and “Neuroplasticity.”

Given our current understanding of the brain regarding both neurogenesis and neuroplasticity, the potential recovery of stroke victims has become optimistic. Research and clinical results have confirmed this optimism. Now treatments are undertaken that would never have been considered under the previous views of the brain. Moreover, treatments are undertaken for much longer periods as it has been shown that stroke victims can regain functions even years after a stroke with ongoing therapy. A previous Healthymemory Blog post, “Transactive Memory: An Aid to Short and Long Term Memory and to Stroke Recovery,” expounds, as the title indicates, on how transactive memory can aid in stroke recovery.

According to Brave New Brain, the future will bring new technologies to prevent damage, renew damaged areas, and replace neurons. One particularly interesting project discussed in the book is the development of an artificial hippocampus. One cannot overemphasize the important role the hippocampus (actually there are two hippocampi, one in each hemisphere of the brain) plays. Perhaps important role is in the long term storage of memories. If the hippocampus does not function properly, new memories are no longer formed (enter “hippocampus” into the search box to find more Healthymemory Blog Posts discussing the hippocampus.).

One should not underestimate the difficulties this project needs to address. First of all, it needs either to identify information to be stored in long term memory or to have this information pre-identified. Storing everything in long term memory would be overwhelming and stultifying. Then you would need to learn how to code the information for memory storage. Finally, you would need to know where to send this information. It is likely that it would need to be sent to many places in the brain. Moreover, the where to send requirement would probably be determined or influenced by the kind of information to be stored. An effective artificial hippocampus probably remains something to be developed in the distant future, if it is ever developed. Nevertheless, it is an important structure, one that certainly warrants investigation. What is learned, even given the ultimate failure of the project, could be quite valuable in our understanding of how human memory works.

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

© Douglas Griffith and healthymemory.wordpress.com, 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 healthymemory.wordpress.com with appropriate and specific direction to the original content.

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July 15, 2010

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Can Technology Be Harmful to a Healthy Memory?

June 13, 2010

A piece by Nicholas Carr in the Outlook Section of the Washington Post, “In Google we trust, a bit too much,” (June 6, 2010 B3) raised some interesting questions about the possible harmful effects of technology. The specific Google feature addressed in this piece was the directions one can request from Google. Of course directions can be found in a variety of sources besides Google, but the general concern was using Global Positioning Systems (GPS) for navigating ourselves. The Healthymemory Blog previously presented the study (“How Memory Works”) regarding the size of the hippocampi of London cab drivers. The hippocampus (its plural being hippocampi) is a brain structure essential for effective memory, particularly for the storage and retrieval of new memories. To receive a license as a London cab driver there is a test that requires the candidate driver to commit to memory the entire map of London. Drivers who earn this license had hippocampi that are larger then normal. The neuroscientist who led this study, Eleanor Maguire, fears that if London cab drivers adopt satellite navigation, their hippocampi will shrink with the consequent loss of much of their remarkable navigation sense. She is quoted as saying “We very much hope that they don’t start using it.”

So one expressed fear is that increasing reliance on GPS systems will result in the loss of our navigational skills (personally, I have little in the way of skill to lose here). Carr raises the larger fear that shrinking hippocampi, due to an increasing reliance on technology, could result in increases in Alzheimer’s Disease and senile dementia.

Readers of the Healthymemory Blog might regard this as a contradiction of the one of the premises of the blog that technology can results in increases in brain health. There is no real contradiction here. Whether technology is helpful or harmful depends on how technology is used. When one considers the potential of future technology, for example, the translation of written and spoken foreign languages, there is the possibility that we could become mental weaklings all too dependent on this technology. One can find a ready analogy to physical fitness where some of us are obese and/or in poor physical condition due to the many options in transportation that technology offers as well as the many options in sedentary entertainment.

However, technology can be used to enhance healthy memories. There are so many opportunities to learn new and interesting information and skills that do exercise our hippocampi. Getting information into our brains so that is retrievable exercises our hippocampi. Even learning how to find and retrieve information from transactive memory exercises our hippocampi. Moreover, we can exercise our hippocampi directly by using the mnemonic techniques presented in the Healthymemory Blog to learn new information.

© Douglas Griffith and healthymemory.wordpress.com, 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 healthymemory.wordpress.com with appropriate and specific direction to the original content.