Saturday, June 25, 2016
The price we pay for living is dying. That is, to stay alive, our body must burn oxygen, and that process inevitably yields toxic metabolites called free radicals. Free radicals are highly reactive because the outer shell of electrons is incomplete. Atoms are attracted to other atoms with incomplete electron shells. That is, they share electrons to form a chemical bond. An atom that has a full outer shell tends not to enter into chemical reactions.
The damage comes from the free radical stripping electrons off of target atoms and converting them into a chain-reaction production of free radicals. This changes the target atoms so that their normal function is disabled. Such damage occurs in all sorts of molecules, including the vital molecules RNA and DNA.
So how do anti-oxidant chemicals help? They neutralize radicals by donating electrons to complete the outer shells of free radicals without becoming free radicals themselves. Think of anti-oxidants as scavengers that go around scooping up free radicals and neutralizing them.
Fortunately, nature provides us with chemicals that reduce the amount of free radicals. These are called anti-oxidants because they neutralize free radicals by donating one of their own electrons, ending the electron-"stealing" reaction. The antioxidant nutrients thus reduce cell and tissue damage. The best way to get these anti-oxidants is through eating a good diet. However, as we age, diet is often insufficient to provide enough anti-oxidants, and we need to increase our intake with supplement pills or capsules.
The table below suggests a daily regimen of healthful chemicals, anti-oxidants and a couple of other chemicals that slow aging even though they are not anti-oxidants. The idea is that combining different types of anti-oxidants and other substances known to slow aging should expand the breadth of their coverage and produce additive beneficial effects. Maybe they would act synergistically so that the benefits are super-additive—that is, more than the sum of the benefits of each individual anti-oxidant. This idea has never been tested to my knowledge, but it seems so plausible that I think we would all benefit from the combination. Most benefit might occur when the anti-oxidants are taken on an empty stomach. It is likely that some portion of an anti-oxidant can be inactivated or sequestered by binding with food and thus reducing the absorption into the blood stream. Avoid using sugar, as many are tempted to do with the coffee, tea, or chocolate. I recommend using artificial sweetener.
Omega-3 fatty acids are powerfully anti-inflammatory. Inflammation is a major cause of aging, and these fatty acids, found also in deep sea fish, have well-proven strong benefits on aging.
Finally, I add that other factors also have major anti-aging effects, such as regular exercise and weight control. Regular doctor checkups become increasingly necessary as one ages.
I have written about some of these anti-oxidants before (see references below). Two of the substances on my wellness list, cocoa and melatonin have not been discussed in my previous blogs. In animal studies, cocoa has been shown to improve memory and to increase brain levels of a chemical (brain-derived neurotrophic factor) that promotes connections between neurons. A recent study in seniors revealed that 900 mg of cocoa powder per day for three months produced significant improvements in formal thinking tests. Brain scans showed measurable increases of cerebral blood volume in the hippocampus, the area of the brain that promotes memory formation.
Melatonin has two benefits. It is not only a powerful anti-oxidant, but if taken just before bedtime, it helps you have a sound and more resting sleep.
I can't say that this regimen will make you live longer. But it will make you live better. I know this from personal experience, now that I am about to turn 82. If you have health problems, this regimen will surely help. However, you should check with your physician to identify anything on this list that would be contra-indicated for your particular problem.
Readers wanting to know more about slowing aging and boosting brain function should get Memory Medic's e-book " Improve Your Memory for a Healthy Brain. Memory Is the Canary in Your Brain's Coal Mine" for only 99 cents at Smashwords.com.
Thursday, June 09, 2016
Across the nation, there are three common ways to increase school choice: charter schools, vouchers (subsidies) to help pay for private school, and tax credits for companies that donate supplemental funds for voucher programs. All three approaches have serious deficiencies, and I propose two better alternatives.
But first, what is wrong with the current options? Charter schools are relatively unregulated, compared to regular public schools. They often are special-purpose schools that do not offer solutions for the broad swath of typical students. A common problem with school-choice options such as vouchers and tax credits is that such bills will be tied up in court challenges on the grounds that public money is being diverted to private, profit-making schools. The widely popular Nevada program, for example, is now held up in court.
Voucher programs provide only part, often around a half, of the cost of private schools. In the Nevada plan, the state transfers up to $5,700 per child directly to the parents. But the national average private school tuition is approximately $9,518 per year. Thus the shortfall means that only people who have the means can pay the difference. In other words, voucher programs are a subsidy that clearly discriminates against the poor and minorities. How can that survive court challenge?
Also, think about what happens to a public school when all the middle class students transfer out. Public schools can be undermined in another way as well. In Nevada, for example, all the funds that normally would go to the public school are transferred, thus removing support for overhead costs of running a school (utilities, janitorial service, physical plant maintenance, etc.). In addition, a new bureaucracy has to be created to administer the program and monitor allowable expenditures by every participating parent.
Arm waving and lip service will not do. We must seek better options. One option is to privatize the management of public schools. An innovative approach has been enabled by Louisiana Senate Bill 432, passed on May 12, 2016, which transfers oversight of charter schools to local school boards. In the New Orleans Parish district, historically shamefully inadequate, there is now the opportunity to put schools under contract management. Basically, the program allows the school district to convert all public schools into charter schools, controlled by safeguards from abuse by supervision of the Orleans Parish school board and state law. Each school can have complete autonomy over all areas of school operations, such as school programming, instruction, curriculum, materials and texts, business operations, and personnel management. Further details are provided in the documents listed below.
Parents can send their children to any school in the district, and all schools must use the district-wide enrollment and expulsion system. Schools that develop so much excellence that enrollment limits are reached can create lottery admission policies. This puts enormous pressure on the local board to hire contractors who can upgrade the performance of the other schools. Multiple contractors are not only allowed but encouraged. Boards have the authority for competitive bidding processes that ensure competition among the various schools it also makes sense to allow students to transfer from one public school to another, or even to a public school in an adjacent country. Florida just passed such a law.
In Louisiana, safeguards include the requirement that each charter school must have independent third-party administration and monitoring of state high-stakes tests. The state Department of Education can withhold funding from any school districts that under-perform or abuse these new liberties. Local boards have authority to close a charter school. The state superintendent of education can rescind the charter for any school that is being inappropriately protected by a local school board.
A second option that I propose is to break up mega-enrollment schools into smaller schools-within-a-school as separate units that face open competition for enrollment. Carving out smaller schools would increase school choice because there would be more schools and more competition. They could be managed in the usual ways or as in New Orleans by independent, competing contractors. Note that the philosophy is akin to that used in premier universities like Oxford, where separate small, relatively autonomous "colleges" are embedded within the university.
Inner city schools with enrollments of several thousand or more are common after the sixth grade. This has helped to create the dysfunction in inner city schools. It is a well-documented fact that smaller schools produce better student learning. That is why you don't see private mega-schools. Super-sized schools breed attitude and behavior problems and are bad for education quality because:
- Students become part of a herd collective, losing individuality and personal attention from teachers who know them well.
- Students have less opportunity to hone leadership skills or to participate in key extracurricular activities.
- Behavior and security problems are greater. Teenagers have enough trouble "finding themselves" emotionally and socially without being swallowed up as just another number passed from teacher to teacher who can't possibly know much about everybody's learning and emotional needs and problems.
- Students in mega-schools face fierce and demotivating academic and social competition. Only a few get to participate in the popular extracurricular activities. School can cease to be fun. Almost a third of public school students quit, and many more just drift through. Minorities are especially harmed.
- In this school-within-a-school model, the small schools may grow too large because of population growth in the community. But if that happens, the district can build new schools with the same school-within-a school philosophy. The philosophy
In this school-within-a-school model, the small schools may grow too large because of population growth in the community. But if that happens, the district can build new schools with the same school-within-a school philosophy.
Small schools can still have the same amenities as mega-schools if the districts create shared facilities, such as cafeteria, stadiums, sports arenas, gyms, band rooms, vocational education shops, special-needs or advanced placement teachers, administrative staff, etc. With shared facilities, construction costs are reduced. Support staff might actually be cut if many facilities were shared. For academic instruction in low-enrollment subjects, like calculus, a small band of roving specialty teachers could service several small schools.
There is no justification for extra administrators. The principal and staff that now serve a school of three thousand can just as readily service five schools of 600 each. The core of quality education lies in the teachers, who will do their best if they have autonomy and competition.
In summary, educational policy wonks and legislatures should stop pursuing controversial and flawed choice options and consider these two models. Both offer more choice, do not discriminate against the poor and minorities, do not undermine public schools, easily pass court challenge, and are likely to produce better educated children. The public does not have to embrace subsidies of private schools to get more school choice.
Districts may be slow to implement such reforms, because in many districts, the superintendents and their boards have comfortable cozy relationships. But once parents have access to better options, they will elect the kind of board members who demand real change.
Friday, May 27, 2016
I have written several earlier posts on the value of teaching and learning cursive. A recent infographic provides a nice summary of the advantages of handwriting over the keyboard. Handwriting engages the brain more deeply in creative thinking.
Among its many advantages claimed in the infographic, handwriting:
- Provides children with a clearer understanding of how letters form words, sentences, and meanings.
- Teaches reading skills
- Improves memory retention
- Promotes critical and creative thinking (note taking, mind maps, etc.)
And now there is a slick newway of teaching cursive, invented by Linda Shrewsbury. She analyzed all the alphabet letters to see if there were common pen strokes that were common to many letters. She found that handwriting all the letters could be mastered by learning just four simple pen strokes. So she wrote a book, Cursive Logic, that explains how to learn cursive by first learning these four basic strokes. Instead of spending hours, days, and weeks learning how to copy each letter in an attractive and readable way, you practice the four strokes (which can be mastered in less than an hour). Then with these mastered, you quickly learn how to apply the strokes appropriately to the letters in four short lessons.
Monday, May 23, 2016
Post-traumatic stress disorder (PTSD) is a common form of fear memory, in which a pervasive emotional stress is created by remembering experiences that evoked fear. If our brains could forget the fear memory, PTSD would decay away. Why can't we forget fear memories? In part, it is because they keep getting rehearsed, and much of this rehearsal occurs during our dreams. One major normal function of sleep is to help the brain to strengthen memory of things, good and bad, that happened during wakefulness.
Recent animal research suggests how the brain accomplishes this memory strengthening (called consolidation). More importantly, consolidation is manipulable. The study began with the established understanding that memories are of two kinds: explicit (episodic) and implicit (procedural). Fear memories are episodic; that is, we remember the episodes in our life that were traumatic. Episodic memories are laid down by a structure in the brain known as the hippocampus, a part of the cerebral cortex that is folded underneath the main cortex and has different internal structure and connections with other parts of brain. Moreover, the hippocampal consolidation effect is exerted when it generates a voltage rhythm of roughly 6-10 waves per second that also contains nested higher frequencies (gamma) of about 30-90.
With this background of information, researchers at McGill University in Canada* decided to see how fear memory might be affected by disrupting hippocampal theta rhythm, which in sleep occurs during the REM (dream) stage of sleep. The study was conducted in mice, monitored during their sleep, soon after they were trained to remember certain objects and also after they had learned a conditioned fear memory. The object-learning task was to remember where a novel object had been placed (the hippocampus is also known to provide the brain with spatial location information). The other learning task, and the one relevant to PTSD, involved exposing awake mice to a sound warning followed by electrical shock to their feet. They manifested the associated fear learning by freezing all movement as soon as the sound cue was heard, before the foot-shock was actually delivered.
The key part of the experiment was the ability to shut down theta activity. Other workers had shown that neurons can be made hypersensitive to laser light by injecting their environment with a virus that is fused to a fluorescent protein. The location of neurons that drive theta rhythm is known, and so the researchers injected such a virus into that area and also implanted a fiber optic that could deliver laser light on those neurons. Neuronal activity in this area could be stopped whenever laser light activated the protein.
With both memories of object location and conditioned fear, testing for recall on the next day revealed that memory formation was prevented by blocking theta activity during the preceding REM sleep when the blocking occurred during a critical four-hour period immediately after initial learning. Similar activity disruption during the non-dream, non-theta, stage of sleeping did not prevent either form of memory.
Even if you could use this laser-light technique in humans (and theoretically you can), you might say this approach could not work because it is usually not practical to institute formal therapy within four hours after an initial emotionally traumatic experience. But, a common current PTSD therapy is based on the established phenomenon of re-consolidation of memory. Every time you recall a memory, it has to be re-stored, and thus it is susceptible to modification (by talk therapy, for example). The revised memory can replace the original fear memory. A therapist could have a patient recall the bad experience, go to sleep right away, and receive light blocking of theta to disrupt the re-storage of the bad memory. Perhaps a simpler approach would be to get good dream sleep soon after talk therapy, which might help cement the revised, less traumatic memory.
*It was at McGill, about a half-century ago, that the role of the hippocampus in memory formation was first discovered.
Boyce, Richard, et al. (2016) Causal evidence for the role of REM sleep theta rhythm in contextual memory consolidation. Science. 352, 812-815.
For more information about learning and memory, consult Memory Medic’s recent book, Memory Power 101.
Saturday, April 30, 2016
First, the facts: Common Core (CC) is not working, as measured by its own standards and metrics. After seven years of implementation in 40 states, Associated Press now summarizes the National Report Card that reveals that two-thirds of graduating seniors are not ready for college. Seventy-five percent failed the math test and sixty-three percent failed the reading test.
These dismal findings are no surprise, as we get similar reports every year during CC's reign. Everybody seems to have an explanation, which too often is an excuse—like we don't spend enough money on schools. That conclusion is easily refuted by extensive documentation, and I won't take the time to rehash that evidence here. But let's look at some possible explanations that are widely shared and perhaps real:
Teaching to the Test. The problem with CC is not so much with its standards but with the testing regimen that has been captured by two publishing houses. The federal government education bureaucrats ("educrats") have turned schools into test factories for CC-based testing. In other areas of politics, we would call that crony capitalism. The focus of teaching in many schools is to teach students to pass multiple-choice tests limited to specific standards in only two areas, math and English. In the old days, we practiced learning the multiplication tables; today, kids practice taking tests—again and again. If teaching to the test worked, maybe we could endorse the practice. But it clearly doesn't work. Why? This leads us to other explanations.
One Size Fits All. Federal educrats treat our hugely heterogeneous population as if it were homogeneous. If you live in the Southwest, you know that this part of the country is largely Mexicanized, with huge numbers of students who don't even speak English. The country as a whole is a mixture of suburbia and ghettos. The government promotes multi-culturalism, while at the same time demands that our schools produce a cookie-cutter product. We have Red and Blue states that seem to be moving further apart. We have growing disparities in personal wealth, aspirations, and family structure. It is a fool's errand to think that one size fits all is the remedy for education.
Political Correctness. CC is notorious for its PC curriculum, which contains significant elements of anti-Americanism and leftist doctrine that have little to do with education. Moreover, for many students, such PC is demotivating. Kids do have a capacity for spotting when they are being manipulated by adults. They do not like it, especially when it is imposed in school.
State-centric versus Student-Centric Education. Students live in a different mental world than adults. Our standards of learning are not inherently theirs. Whatever it is we say they must learn has to be put in a context that is meaningful to them. Math, for example, taught as an isolated subject, has little attraction for most students, especially when the only purpose is to pass a federally mandated exam. However, when taught as a necessary component of a shop class or classes in other subjects, math acquires a relevance that even students can value. Language arts, when studied as an end itself, is hardly as motivating as when students learn it to accomplish their own purposes, like perhaps debating with peers, writing persuasive blogs and social media posts, or school publications. I think that educrats have forgotten what it is like to be a youngster.
Trashing Memorization. CC was designed to abandon the old emphasis on memorization and focus on teaching thinking skills. This is most evident in math instruction. Learning to think is of course admirable, but why then do we not see improvement on the tests designed to measure thinking skills? Do educrats not know that you think with what you know, and what you know is what you have memorized?
I have professor colleagues who criticize me for trying to be a "Memory Medic" and help students learn how to memorize more effectively. Teachers seem reluctant to teach memory skills, or maybe they don't know what the skills are. Even if teachers can teach such skills, their principals and superintendents set the demands that are focused on teaching to the test. Teaching learning skills these days is an alien concept.
What schools need to focus on is helping students to develop expertise in something. That may be in band, art, vocational classes, farm projects, or any area where skills are valued. CC does none of that. The real world needs and rewards expertise. Of course, experts can think well in their field of expertise. And why is that? They know their subject.
When a student memorizes information, she not only acquires subject-matter mastery but the personal knowledge of success. Nothing is more motivating than success. A student owns the success. Nobody can take that away. Federal exams remind students of their ignorance. And we expect that to be motivating?
When I went to school decades ago, school was fun, because I was learning cool stuff and nobody was on my back all year long to make the teacher and school to look good with my test scores. Today, a lot of kids hate school. I would too.
"Memory Medic" has three recent books on memory:
1. "Memory Power 101" (Skyhorse) - for a general audience at http://www.skyhorsepublishing.com/book/?GCOI=60239100060310http://www.skyhorsepublishing.com/book/?GCOI=60239100060310
2. "Improve Your Memory for a Healthy Brain. Memory Is the Canary in Your Brain's Coal Mine"- an inexpensive e-book for boomers and seniors in all formats at Smashwords.com, https://www.smashwords.com/books/view/496252https://www.smashwords.com/books/view/496252
3. "Better Grades, Less Effort" - an inexpensive e-book for students at Smashwords.com, https://www.smashwords.com/books/view/24623https://www.smashwords.com/books/view/24623
Tuesday, April 26, 2016
As explained in my memory-improvement book, "Memory Power 101," the most powerful way to remember something is to construct a mental-image representation. All the memory books I have read make the same point. The professional memorizers, "memory athletes" who can memory the sequence of four shuffled decks of cards in five minutes, all use some form of mental imaging that converts each card into a mental-picture representation.
Now a recent experiment documents the power of mental images in a study involving seven experiments that compared memory accuracy with whether or not a drawing was made. College-student volunteers were asked to memorize a list of words, each of which was chosen to be easily drawn. Words were presented one at a time on a video monitor and students were randomly prompted to write the name of the object or make a drawing of it. Each word presentation was timed and a warning buzzer indicated it was time to stop and get ready for the next word display. At the end of the list, a two-minute filler task was presented wherein each student classified 60 sound tones, selected at random, in terms of whether the frequency was low, medium, or high. Then a surprise test was given wherein students were asked to verbally recall in one minute as many words as they could, in any order, whether written or drawn.
In the first two experiments students remembered about twice as many when a drawing representation had been made than when just the word had been written. Three other experiments demonstrated that drawing was more effective because the encoding was deeper. For example, one experiment was conducted like the first two, but included a third condition in which the subjects were to write a list of the physical characteristics of the word (for example, for apple, one might say red, round, tasty, chewy, etc.). This presumably provides a deeper level of encoding than just writing or
Another highly important experiment was conducted that compared drawing and writing with just making a mental image without drawing it. Again, drawing produced the best results, although more words were remembered when mentally imaged than when written.
A follow-on experiment substituted an actual picture of the word instead of requiring the student to actively imagine an image. Here again, best results occurred with drawing, with seeing pictures being more effective than writing the word.
In a sixth experiment, drawing was still superior to writing even if the list of words was made longer or if the encoding time was reduced. In the last experiment, drawing was still beneficial in a way that could not be explained solely by the fact that drawings are more distinctive than writing a word.
The benefits of drawing were seen within and across individuals and across different conditions. The researchers concluded that drawing improves memory by encouraging a seamless integration of semantic, visual, and motor aspects of a memory trace. That makes sense to me.
The processes involved here that account for better memory are 1) elaborating the item to be remembered, 2) making a mental image of it or an alias for it, 3) the motor act of drawing the image, and 4) the reinforcing feedback of thinking about the drawing.
The implications of studies like this have enormous practical application for everyday needs to remember. The principle is that whenever you have something you need to remember, make a mental-image representation of it and then draw it. For example, if you have to remember somebody named "Mike" make a mental image of the person speaking into a microphone (mike). Then roughly draw Mike's main facial features alongside a microphone. There are all sorts of formal schemes for making mental images, even for numbers, as explained in my book. This present study indicates that the making of a mental image is powerfully reinforced when you try to draw it.
To some extent, this memory principle is used in elementary school, where drawing is a huge part of the curriculum. As students get older, teachers abandon drawing and usually so do the students. Perhaps educators need to revisit the idea that drawing has educational value at all grade levels.
Kluger, Jeffrey, (2016) Here's the memory trick that science says works. Time, April 22. http://time.com/4304589/memory-picture-draw/
Wammes, Jeffrey D. et al. (2016. The drawing effect: Evidence for reliable and robust memory benefits in free recall. The Quarterly Journal of Experimental Psychology. 69 (9), 1752-1776. DOI:10.1080/17470218.2015.1094494
Saturday, April 16, 2016
We all think with ideas and information that we hold in working memory. Working memory is like a scratch pad with a succession of content on the pad that is streamed into the brain's thinking apparatus. What is held on the working memory scratch pad is either retrieved from memory or inserted from real-time experience (like what you are reading or hearing).
Source: W. R. Klemm
So, how does organization apply? As the brain seeks information to put on the scratch pad, it has to know where it is. Thinking is slow at best and possibly incoherent if ideas and information are located in disorganized repositories (such as sticky notes, memos, documents located randomly in different places. How can anyone keep a stream of coherent thought going if there is constant interruption trying to find the note or document one needs at each stage of thinking?
The other thing is that working memory has very limited capacity. Thus, when accessing notes and documents to use in thinking, the content needs to be easily extractable in small chunks. Here is an example that we can all relate to. Congress seems wedded to producing omnibus bills of some 2,000 or more pages. Even if legislators read the entire bills, they couldn't digest the content in any coherent way because the bills are not designed for thinking. No surprise then that we end up with incoherent, ineffective, and even destructive legislation.
Common Sense Methods for Organizing. The underlying principle should be to have a place for everything and put everything in its place. Examples:
- Put important items (bills, car keys, purse, etc.) in their own same place.
- Put sticky note reminders in key places.
- Keep a calendar (but remember to check it each day).
- Get a file cabinet and label the files in the most meaningful ways.
- Have a tote bag or briefcase that always has in it what you need for the day.
Be proactive. If information of a given type accumulates over time, don't wait until the end to organize it. Organize as it goes along. For example, my federal tax information accumulates throughout the year. I don't wait until tax time to organize it. As bills, receipts, and the like come in during the year, I file them in file cabinet folders I have already set up for income tax return preparation. Come April, I can put all the information the tax accountant needs in a matter of a few minutes. And it reduces his time, which lowers my tax preparation bill.
Computer Methods. Computers give us access to enormous amounts of information. But the bad news is that the more information, the greater the need for good organization.
In the case of web-site addresses, most browsers have good systems for bookmarks, but after a couple years of saving bookmarks I find that I have not been sufficiently thoughtful as to how I set up folders and sub-folders.
For other kinds of information, the demand for organizational sophistication varies with the home and workplace workload. Here are a few, free, computer tools:
Tools that Synchronize Across Devices
- One-Note On-line is included in Microsoft Windows. It allows creation of separate notebooks, and labeled "pages" within each notebook that accept separately pasted items that can be dragged about the page.
- Evernote helps you keep all sorts of notes in topic-specific notebooks.
- Google Docs is like Evernote, but is document focused.
- Google Calendar helps you track events, set reminders, import appointments straight from Gmail, and is shareable.
- Remember the Milk is a "to-do" reminder. It has specific apps for the web and multiple portable devices and you can connect it to multiple devices. It syncs with Outlook or Google mail.
- TelePixie sends wake-up calls, reminders, and alerts to your mobile phone.
- Sticky Notes comes with Microsoft Windows and is a computer version of the paper sticky notes you put on the refrigerator, walls, and elsewhere. You can keep the notes open all the time on the computer desktop or temporarily closed.
- Stickies is a much more sophisticated system that runs on Windows. Unlike Sticky Notes which appear all at once on the desktop, Stickies notes are separately attached only to whatever document you are working on.
- Flashcards provides a simple way to create flashcards with the information you are trying to learn and drill yourself to help make it stick in your mind.
- WiseMapping is a mind mapping tool that provides you with an awesome way to keep notes in an organized fashion. Items in the map can have attached text commentary. Maps can be shared and exported in multiple formats.
Readers wanting to know more about how the brain works may be interested in Dr. Bill's recent book, Mental Biology (Prometheus).
Saturday, March 12, 2016
The title sounds outrageous. But supporting data comes from research at the most prestigious Salk Institute. Other researchers had made enormous storage capacity estimates for brains, but this new estimate is 10 times greater. The estimate is on the order of petabytes, as much as the entire World Wide Web.
How does anybody come up with such estimates? What is the basic premise? First, memory is quantified in terms of number of bits of information that can be stored and recovered. In the case of brain, the question is how much information can be stored in a synapse, the communicating junction between neurons. Size and operational strength of a synapse are the key variables: strength can be measured in bits and strengths correlate with umber and size synaptic size. Under high magnification, synapses look like a bunch of beads on a string. The newborn brain, there are relatively few “beads,” but these increase in number and size as the baby grows and learns things. Sadly, in old age, many of these beads disappear unless the brain is kept very active.
In the Salk study of rat brains, electron micrographs of the memory-forming structure, the hippocampus, allowed 3-D reconstruction and detection of the diameters of synapses, which are the target synaptic structures in neurons. Synaptic strength correlates with storage capacity, and the strength is measured by the size of synapses, which appear as a round bead attached to a stalk or neck to the supporting neuronal membrane. The size of the bead varies with synaptic strength because synaptic strength is created by more molecular machinery for mediating synaptic communication. Thus, spine bead size is a proxy for synaptic strength and storage capacity.
The investigators found that a small cube of brain tissue contained 26 different bead sizes, each associated with a distinct synaptic strength. The authors state that this equates to an approximate 4.7 bits of information at each synapse. Multiply 4.7 times the trillions of synapses and neurons in the brain and you get phenomenal storage capacity.
While I marvel at the elegant complexity of these research methods, I think the interpretations are a bit simplistic. There are some caveats that the authors overlooked. For one, an assumption is made that that the number of storage bits equals the logarithm of the number of bead sizes. The “bit” is a unit of information in digital communications. Information theory holds that one bit is the probability of a binary random variable that is 0 or 1, or more loosely defined as present or absent. One has to take some liberties to apply this concept to memory storage in brain, because the brain is not a digital computer. It is an analog biological computer.
Then there is the problem that the hippocampus deals only with forming declarative and episodic memories, not procedural memories like touch typing or playing the piano. Thus, the storage capacity, whatever it is, is not estimated for procedural memories. Secondly, declarative and episodic memories are not stored in the hippocampus, but rather stored in a distributed fashion throughout the brain. Since synaptic measures were made only on hippocampal tissue, there are no data for the rest of the brain.
But there is a larger issue. How does one know how many bits it takes to represent different memories? Not all memories are the same and surely they don't all require the same number of storage bits.
Actually, the exact number of bits of information that brains can store is rather irrelevant. By any measure, common experience teaches that nobody utilizes all their memory capacity. Moreover, the amount of information a given person stores varies profoundly depending on such variables as motivation to remember things, use of mnemonics, and level of education. The question that needs answering, given that we have vast amounts of unused storage capacity, is "Why don't we remember more than we do?" Books like my Memory Power 101 provide some practical answers.
Bartol, Thomas M. et al. (2015). Neuroconnectomic upper bound on the variability of synaptic plasticity. eLIfe. Nov. 30. http://dx.doi.org/10.7554/eLife.10778