Brain Facts:
Memory

Brain
—Lies of Omission

The brain commits may lies of omission, as it discards most of the information in the world as soon as it is deemed to be unremarkable.

Change Blindness

Throwing away information, taking mental shortcuts, and inventing plausible stories come together in what psychologists call “change blindness.”

Cancer therapy can save your life, but it can also cause “chemo brain,” the mental fogginess and memory and concentration problems that can persist for years after treatment has ended.

Crystallized vs. Fluid Intelligence

Eyewitness
—Unreliable

Eyewitnesses are notoriously unreliable, in part because they imagine—as most of us do—that they see and remember more detail than they really can.

Lawyers can use this knowledge to discredit witnesses by tempting them to say they saw something that the lawyer can disapprove, casting doubt on the rest of the witness’s testimony.

Hippocampus

The hippocampus is a subcortical structure that is divided into two parts, which are connected by a band of fibers. It is believed to play an important role in memory.

Hippocampus
—Central Organ for Learning

The hippocampus, near the amygdala in the midbrain, is our central organ for learning. This structure enables us to convert the content of ‘working memory’—new information held briefly in the prefrontal cortex—into long-term form for storage.

Hippocampus
—Cortisol

The Cortisol stimulates the amygdala while it impairs the hippocampus, forcing our attention on the emotions we feel, while restricting our ability to take in new information. Instead we imprint what is upsetting us. After a day when a student gets panicked by a pop quiz, he’ll remember the details of that panic far more than any of the material in the quiz.

Hippocampus
—Neuropeptide  Receptors

The hippocampus of the brain, without which we cannot learn anything new, is a nodal point for neuropeptide receptors, containing virtually all of them.

Hippocampus
—Retention of Memories

Everything that happens to us in life, all the details that we will remember, depends on the hippocampus to stay with us. The continual retention of memories demands a frenzy of neuronal activity. In fact, the vast majority of neurogenesis—the brain’s production of new neurons and laying down of connections to other—takes place in the hippocampus.

Human Brain

Because the human brain packs so much circuitry in so little space, it creates continuous pressure to extinguish connections the brain no longer needs, not make space for those it must have. The adage “use it or lose it” refers to this ruthless neural Darwinism, where brain circuits vie with one another to survive. Those neurons we lose are “pruned,’ disappearing like twigs cut from a tree.

Learn
—Declarative Memory

One study showed that a combination of smell and sleep improved declarative-memory consolidation. The game involved a specialized 52-card deck resplendent with 26 pairs of animals. You turn all cards face down, and then start selecting two cards to find matches. It is a test of declarative memory. The one with the most correct pairs wins the game.

In the experiment, the control groups played the game normally. But the experimental groups didn’t. They played the game in the presence of rose scent. Then everybody went to bed. The control groups were allowed to sleep unperturbed. Soon after the snoring began in the experimental groups, however, the researchers filled their room with the same rose scent. Upon awakening, the subjects were tested on their knowledge of where the matches had been discovered on the previous day. Those subjects without the scent answered correctly 86 percent of the time. Those re-exposed to the scent answered correctly 97 percent of the time. Brain imaging experiments showed the direct involvement of the hippocampus. It is quite possible that the smell enhanced recall during the offline processing that normally occurs during sleep.

In the highly competitive world of school performance, there are parent who would die to give their kids an 11 percent edge over competition.

Memories

Our memories are in part reconstructions. Whenever we retrieve a memory, the brain rewrites it a bit, updating the past according to our present concerns and understanding. At the cellular level, LeDoux explains, retrieving a memory means it will be “reconsolidated,” slightly altered chemically by a new protein synthesis that will help store it anew after being updated.

Thus each time we bring a memory to mind, we adjust its very chemistry: the next time we retrieve it, that memory will come up as we last modified it. The specifics of the new consolidation depend on when we learn as we recall it. If we merely have a flare-up of the same fear, we deepen our fearfulness.

Memory

Memory defines who we are, now and at every moment. It also defines our future, because without memory ability, we cannot make plans and think ahead. And, of course, without memory, it’s as if we have no past.

Memory biases may either enhance or impair the recall of memory, or they may alter the content of what we report remembering.
There are many memory biases including the humor effect, positivity effect and the generation effect.

Humor effect states that humorous items are more easily remembered than non-humorous ones.

Positivity affects states that older adults favor positive over negative information in their memories.

Memory Strategies

Memory strategies activate a network of brain regions known to be involved in spatial navigation and memory.

Memory
—Antioxidants

Swiss researchers recently found that high blood levels of antioxidant vitamin C and beta-carotene actually predicted a superior memory in old age. In a large ongoing study of aging, Walter J. Perrig, Ph.D., and colleagues at the University of Berne recently tested the memory performance of 442 healthy men and women ages sixty-five to ninety-four: Dr. Perrig compared their memory scores with blood samples, taken recently and twenty-two years previously. Strikingly, those with the most blood vitamin C and beta-carotene, at both time periods, scored highest on test of memory involving recall, recognition, and vocabulary.

Psychologists have found that thought patterns used to recall the past and imagine the future are strikingly similar. Using functional magnetic resonance imaging to show the brain at work, they have observed the same regions activated in a similar pattern whenever a person remembers an event from the past or imagines himself in a future situation. This challenges long-standing beliefs that thoughts about the future develop exclusively in the frontal lobe.

Remembering your past may go hand-in-hand with envisioning your future! It's an important link researchers found using high-tech brain scans. It's answering questions and may one day help those with memory loss.

For some, the best hope of 'seeing' the future leads them to seek guidance -- perhaps from an astrologist. But it's not very scientific. Now, psychologists at Washington University are finding that your ability to envision the future does in fact goes hand-in-hand with remembering the past. Both processes spark similar neural activity in the brain.

"You might look at it as mental time travel--the ability to take thoughts about ourselves and project them either into the past or into the future," says Kathleen McDermott, Ph.D. and Washington University psychology professor. The team used "functional magnetic resonance imaging" -- or fMRI -- to "see" brain activity. They asked college students to recall past events and then envision themselves experiencing such an event in their future. The results? Similar areas of the brain "lit up" in both scenarios.

"We're taking these images from our memories and projecting them into novel future scenarios," says psychology professor Karl Szpunar.

Most scientists believed thinking about the future was a process occurring solely in the brain's frontal lobe. But the fMRI data showed a variety of brain areas were activated when subjects dreamt of the future.

"All the regions that we know are important for memory are just as important when we imagine our future," Szpunar says.
Researchers say besides furthering their understanding of the brain -- the findings may help research into amnesia, a curious psychiatric phenomenon. In addition to not being able to remember the past, most people who suffer from amnesia cannot envision or visualize what they'll be doing in the future -- even the next day.

BACKGROUND: Researchers from Washington University in St. Louis have used advanced brain imaging techniques to show that remembering the past and envisioning the future may go hand-in-hand, with each process showing strikingly similar patterns of activity within precisely the same broad network of brain regions. This suggests that envisioning the future may be a critical prerequisite for many higher-level planning processes in the brain.

WHAT IS fMRI: Magnetic resonance imaging (MRI) uses radio waves and a strong magnetic field rather than X-rays to take clear and detailed pictures of internal organs and tissues. fMRI uses this technology to identify regions of the brain where blood vessels are expanding, chemical changes are taking place, or extra oxygen is being delivered. These are indications that a particular part of the brain is processing information and giving commands to the body. As a patient performs a particular task, the metabolism will increase in the brain area responsible for that task, changing the signal in the MRI image. So by performing specific tasks that correspond to different functions, scientists can locate the part of the brain that governs that function.

ABOUT THE STUDY: The researchers relied on fMRI to capture patterns of brain activation as college students were given 10 seconds to develop a vivid mental image of themselves or a famous celebrity participating in a range of common life experiences. Presented with a series of memory cues -- such as getting lost, spending time with a friend, or attending a birthday party -- participants were asked to recall a related event from their own past; to envision themselves experiencing such an event in their future life; or to picture a famous celebrity (specifically, former U.S. president Bill Clinton) participating in such an event.

WHAT THEY FOUND: Comparing images of brain activity in response to the 'self-remember' and 'self future' event cues, researchers found a surprisingly complete overlap among regions of the brain used for remembering the past and those used for envisioning the future. The study clearly demonstrates that the neural network underlying future thoughts is not only happening in the brain's frontal cortex. Although the frontal lobes play an important role in carrying out future-oriented operations -- such as anticipation, planning and monitoring -- the spark for these activities may be the process of envisioning yourself in a specific future event. And that's an activity based on the same brain network used to remember memories about our own lives. Also, patterns of activity suggest that the visual and spatial context for our imagined future is often pieced together using our past experiences, including memories of specific body movements: data our brain has stored as we navigated through similar settings in the past.

Smith and Squire assessed the brain activity associated with the recollection of old and new memories. They recruited 15 healthy male participants, and used functional magnetic resonance imaging (fMRI) to scan their brains while they answered 160 questions about news events that took place at different periods of time during the past 30 years. The study sounds simple, but the design of the experiments was actually somewhat complex, because the researchers had to overcome a number of confounding variables.

First, when one is asked to recall any given memory, the brain encodes not only the questions that were asked to cue the retrieval, but also the resulting recollection, so the associated activity could therefore interfere with that which is being assessed. Second, more recent memories are likely to be richer and more vivid than older ones, so the strength of the fMRI signal could be related not just to the time at which a recalled event occurred but also to the richness of the participants' recollection of it. Finally, recalled memories could be strongly associated with personal events in the participants' lives, which could make them easier to remember.

Physical Activity
Short Term Memory

Not every weapon in the cognitive arsenal is improved by exercise. Short-term memory skill and certain types of reaction times appear to be unrelated to physical activity. And, while nearly everyone shows some improvement, the degree of benefit varies quite a bit among individuals. Most important, these data, strong as they were, showed only an association, not a cause.

Study Oxytocin
—Improves  Human Ability to Recognize Faces but not Places

Oxytocin, a hormone involved in child-birth and breast-feeding, helps people recognize familiar faces, according to new research in the January 7 issue of The Journal of Neuroscience. Study participants who had one dose of an oxytocin nasal spray showed improved recognition memory for faces, but not for inanimate objects.

“This is the first paper showing that a single dose of oxytocin specifically improves recognition memory for social, but not for nonsocial, stimuli,” said Ernst Fehr, PhD, an economist at the University of Zurich who has studied oxytocin’s effect on trust and is unaffiliated with the new study. “The results suggest an immediate, selective effect of the hormone: strengthening neuronal systems of social memory,” Fehr said.

In mice, oxytocin has been shown to be important in social recognition — remembering that another mouse is familiar. Unlike humans, who use visual cues, mice use smell to recognize and distinguish other mice.

In humans, oxytocin increases social behaviors like trust, but its role in social memory has been unclear. “Recognizing a familiar face is a crucial feature of successful social interaction in humans,” said Peter Klaver, PhD, at the University of Zurich, the senior author of the new study, which was led by Ulrike Rimmele, PhD, at New York University. “In this study, we investigated for the first time the systematic effect of oxytocin on social memory in humans,” Klaver said.

Klaver and colleagues had study participants use a nasal spray containing either oxytocin or a placebo and then showed them images of faces and inanimate objects, including houses, sculptures, and landscapes. Participants were given a surprise test when they returned the next day — they were shown some of the images they had seen the day before as well as some new ones and were asked to distinguish between images that were “new,” images that they specifically “remembered” being presented, and images they recognized (“knew”) as familiar but could not recall the presentation context.

Volunteers who used the oxytocin spray more accurately recognized the faces they had seen before than did those in the placebo group. However, the two groups did not differ in recognizing the other, nonsocial images, suggesting that oxytocin specifically improved social memory and that different mechanisms exist for social and nonsocial memory. Further analysis showed that oxytocin selectively improved the discrimination of new and familiar faces — participants with oxytocin were less likely to mistakenly characterize unfamiliar faces as familiar. “Together, our data indicate that oxytocin in humans immediately strengthens the capability to correctly recognize and discriminate faces,” Klaver said.

“The study highlights the parallels in social information processing in mice and man, and adds further support to the notion that oxytocin plays a critical role,” said Larry Young, PhD, at Emory University, an expert on oxytocin who is unaffiliated with the current study. “This has important implications for disorders such as autism, where social information processing is clearly impaired,” Young said.

The research was supported by the Swiss National Science Foundation, the Swiss Federal Institute of Sports, and the University of Zurich.

Study
—Jet Lag

Jet lag is not simply annoying; in repeated doses, it can be dangerous to your brain’s health. People who frequently cross many time zones can experience brain damage and memory problems. In one study, flight attendants with five years of service who repeatedly took less than five days between long trips were compared to flight attendants who had two weeks or more between trips. Both groups flew the same number of miles overall. The short-interval group had less volume in the temporal lobe—a part of the brain involved in learning and memory. This group also had problem on a memory test, suggesting that frequent travel had damaged their brain.

The brain damage probably resulted from stress hormones, which are release during jet lag and are known to damage the temporal lobe and memory.

Study
—Brain  Mass Building

A recent study published in the journal Nature found that three months of mental training can alter brain structure and, in essence, build brain muscle.  After the study, volunteers were given MRI brain scans, they were taught to juggle—a mentally challenging task. After three months of juggling, the brain scans were repeated. The time the scans showed significant increase in the volume of gray matter—the outer rim of the brain that is responsibility for thinking and complex reasoning. Either their brain cells had grown larger and developed more extensive connection, or the number of brain cells had increased enough to build brain bulk. However, when the volunteers gave up their new hobby, their brains shrank back to their previous sizes. You can build brain muscle but you have to continue your mental activity to sustain the benefits.

Synapses

Study of hippocampus: Depending on their size, dendritic spines contain from 1-20 (typically three) calcium channels that function as molecular gates. They open in response to electrical stimulation and allow calcium to flow into dendritic spines. Calcium, in turn, triggers biochemical events in the dendrite that modify synaptic strength and thereby encode memories.

Smith and Squire therefore designed their experiments so that they could assess the effects of the age of a memory independently of both the encoding of the test questions and richness of the recollection of the memory. At the beginning of the task, the researchers presented in random order blocks of questions about events in each time period, and they asked participants to indicate whether or not they knew the answer. About 10 minutes later, while still in the scanner, the participants were asked three questions about each news event. First, they were asked to recall the original question they had been asked about the event (to assess how well they had encoded the information). Then, they were asked the answer to that question (to assess the accuracy of recall) and, finally, how much they knew about each of the events (to assess the richness of each memory).

In general, the participants' ability to recall any given news event decreased in relation to the amount of time that had passed since the event had occurred. As expected, they were better able to recollect more recent events than older ones. The researchers also found that the participants' memory of the questions they had been asked, and of the content of each news event, was independent of how long ago the events had occurred. The richness of the participants' memories was also unrelated to when a particular event occurred; the memories of events that occurred in the distant past were often as rich as those of more recent events.

In their analyses, the researchers used only those fMRI data from the questions that had been answered correctly. This data set showed that medial temporal lobe structures (the hippocampus and amygdala) exhibited gradually decreasing activity as the participants recalled progressively older memories. This drop in activity was true for memories of news events that occurred up to 12 years before, but the recollection of events that took place longer than 12 years was associated with a constant level of activity in those areas. The opposite activation pattern was observed in areas of the frontal, parietal and lateral temporal lobes: activity in these areas increased with the age of the news event being recalled, but remained constant during the recollection of more recent events.

Vision
—Blind

Blind people are no better at detecting faint sounds than sighted people…Blind people do have better memory, especially for language.

Visual
—Short Term Memory

Working memory is that collection of temporary storage buffers with fixed capacities and frustratingly short life spans. Visual short-term memory is the slice of that buffer dedicated to storing visual information.  Most of us can hold about four objects at a time in that buffer, so it’s a pretty small space. And it appears to be getting smaller. Recent data show that as the complexity of the objects increases, the number of objects capable of being captured drops. The evidence also suggest that the number of objects and complexity of objects are engaged by different systems in the brain, turning the whole notion of short-term capacity on its head.