Wednesday, November 12, 2008

Jacking into the Brain--Is the Brain the Ultimate Computer Interface?

How far can science advance brain-machine interface technology? Will we one day pipe the latest blog entry or NASCAR highlights directly into the human brain as if the organ were an outsize flash drive?

By Gary Stix

The cyberpunk science fiction that emerged in the 1980s routinely paraded “neural implants” for hooking a computing device directly to the brain: “I had hundreds of megabytes stashed in my head,” proclaimed the protagonist of “Johnny Mnemonic,” a William Gibson story that later became a wholly forgettable movie starring Keanu Reeves.

The genius of the then emergent genre (back in the days when a megabyte could still wow) was its juxtaposition of low-life retro culture with technology that seemed only barely beyond the capabilities of the deftest biomedical engineer. Although the implants could not have been replicated at the Massachusetts Institute of Technology or the California Institute of Technology, the best cyberpunk authors gave the impression that these inventions might yet materialize one day, perhaps even in the reader’s own lifetime.

In the past 10 years, however, more realistic approximations of technologies originally evoked in the cyberpunk literature have made their appearance. A person with electrodes implanted inside his brain has used neural signals alone to control a prosthetic arm, a prelude to allowing a human to bypass limbs immobilized by amyotrophic lateral sclerosis or stroke. Researchers are also investigating how to send electrical messages in the other direction as well, providing feedback that enables a primate to actually sense what a robotic arm is touching.

But how far can we go in fashioning replacement parts for the brain and the rest of the nervous system? Besides controlling a computer cursor or robot arm, will the technology somehow actually enable the brain’s roughly 100 billion neurons to function as a clandestine repository for pilfered industrial espionage data or another plot element borrowed from Gibson?

Will Human Become Machine?
Today’s Hollywood scriptwriters and futurists, less skilled heirs of the original cyberpunk tradition, have embraced these neurotechnologies. The Singularity Is Near, scheduled for release next year, is a film based on the ideas of computer scientist Ray Kurzweil, who has posited that humans will eventually achieve a form of immortality by transferring a digital blueprint of their brain into a computer or robot.

Yet the dream of eternity as a Max Headroom–like avatar trapped inside a television set (or as a copy-and-paste job into the latest humanoid bot) remains only slightly less distant than when René Descartes ruminated on mind-body dualism in the 17th century. The wholesale transfer of self—a machine-based facsimile of the perception of the ruddy hues of a sunrise, the constantly shifting internal emotional palette and the rest of the mix that combines to evoke the uniquely subjective sense of the world that constitutes the essence of conscious life—is still nothing more than a prop for fiction writers.

Hoopla over thought-controlled prostheses, moreover, obscures the lack of knowledge of the underlying mechanisms of neural functioning needed to feed information into the brain to re-create a real-life cyberpunk experience. “We know very little about brain circuits for higher cognition,” says Richard A. Andersen, a neuroscientist at Caltech.

What, then, might realistically be achieved by interactions between brains and machines? Do the advances from the first EEG experiment to brain-controlled arms and cursors suggest an inevitable, deterministic progression, if not toward a Kurzweilian singularity, then perhaps toward the possibility of inputting at least some high-level cognitive information into the brain? Could we perhaps download War and Peace or, with a nod to The Matrix, a manual of how to fly a
helicopter? How about inscribing the sentence “See Spot run” into the memory of someone who is unconscious of the transfer? How about just the word “see”?

These questions are not entirely academic, although some wags might muse that it would be easier just to buy a pair of reading glasses and do things the old-fashioned way. Even if a pipeline to the cortex remains forever a figment of science fiction, an understanding of how photons, sound waves, scent molecules and pressure on the skin get translated into lasting memories will be more than mere cyberpunk entertainment. A neural prosthesis built from knowledge of these underlying processes could help stroke victims or Alz­heimer’s patients form new memories.

Primitive means of jacking in already reside inside the skulls of thousands of people. Deaf or profoundly hearing-impaired individuals carry cochlear implants that stimulate the auditory nerve with sounds picked up by a microphone—a device that neuroscientist Michael S. Gaz­zaniga of the University of California, Santa Barbara, has characterized as the first successful neuroprosthesis in humans. Arrays of electrodes that serve as artificial retinas are in the laboratory. If they work, they might be tweaked to give humans night vision.

The more ambitious goal of linking directly to the hippocampus, a neural structure involved with forming memories, requires technology that has yet to be invented. The bill of particulars would include ways of establishing reliable connections between neurons and the extracranial world—and a means to translate a digital version of War and Peace into the language that neurons use to communicate with one another. An inkling of how this might be done can be sought by examining leading work on brain-machine interfaces.

Your Brain on Text
Jacking text into the brain requires consideration of whether to insert electrodes directly into tissue, an impediment that might make neural implants impractical for anyone but the disabled. As has been known for nearly a century, the brain’s electrical activity can be detected without cracking bone. What looks like a swimming cap studded with electrodes can transmit signals from a paralyzed patient, thereby enabling typing of letters on a screen or actual surfing of the Web. Niels Birbaumer of the University of Tübingen in Germany, a leading developer of the technology, asserts that trial-and-error stimulation of the cortex using a magnetic signal from outside the skull, along with the electrode cap to record which neurons are activated, might be able to locate the words “see” or “run.” Once mapped, these areas could be fired up again to evoke those memories—at least in theory.

Some neurotechnologists think that if particular words reside in specific spots in the brain (which is debatable), finding those spots would probably require greater precision than is afforded by a wired swim cap. One of the ongoing experiments with invasive implants could possibly lead to the needed fine-level targeting. Philip R. Kennedy of Neural Signals and his colleagues designed a device that records the output of neurons. The hookup lets a stroke victim send a signal, through thought alone, to a computer that interprets it as, say, a vowel, which can then be vocalized by a speech synthesizer, a step toward forming whole words. This type of brain-machine interface might also eventually be used for activating individual neurons.

Still more precise hookups might be furnished by nanoscale fibers, measuring 100 nanometers or less in diameter, which could easily tap into single neurons because of their dimensions and their electrical and mechanical properties. Jun Li of Kansas State University and his colleagues have crafted a brushlike structure in which nano­fiber bristles serve as electrodes for stimulating or receiving neural signals. Li foresees it as a way to stimulate neurons to allay Parkinson’s disease or depression, to control a prosthetic arm or even to flex astronauts’ muscles during long spaceflights to prevent the inevitable muscle wasting that occurs in zero gravity.

Learning the Language
Fulfilling the fantasy of inputting a calculus text—or even plugging in Traveler’s French before going on vacation—would require far deeper insight into the brain signals that encode language and other neural representations.

Unraveling the neural code is one of the most imposing challenges in neuroscience—and, to misappropriate Freud, would likely pave a royal road to an understanding of consciousness. Theorists have advanced many differing ideas to explain how the billions of neurons and trillions of synapses that connect them can ping meaningful messages to one another. The oldest is that the code corresponds to the rate of firing of the voltage spikes generated by a neuron.

Whereas the rate code may suffice for some stimuli, it might not be enough for booting a Marcel Proust or a Richard Feynman, supplying a mental screen capture of a madeleine cake or the conceptual abstraction of a textbook of differential equations. More recent work has focused on the precise timing of the intervals between each spike (temporal codes) and the constantly changing patterns of how neurons fire together (population codes).

Some help toward downloading to the brain might come from a decadelong endeavor to build an artificial hippocampus to help people with memory deficits, which may have the corollary benefit of helping researchers gain insights into the coding process. A collaboration between the University of Southern California and Wake Forest University has worked to fashion a replacement body part for this memory-forming brain structure. The hippocampus, seated deep within the brain’s temporal lobe, sustains damage in stroke or Alzheimer’s. An electronic bypass of a damaged hippocampus could restore the ability to create new memories. The project, funded by the National Science Foundation and the Defense Advanced Research Projects Agency, might eventually go further, enhancing normal memory or helping to deduce the particular codes needed for high-­level cognition.

The two groups—led by Theodore W. Berger at U.S.C. and Samuel Deadwyler at Wake Forest—are preparing a technical paper showing that an artificial hippocampus took over from the biological organ the task of consolidating a rat’s memory of pressing a lever to receive a drop of water. Normally the hippocampus emits signals that are relayed to cortical areas responsible for storing the long-term memory of an experience. For the experiment, a chemical temporarily incapacitated the hippocampus. When the rat pressed the correct bar, electrical input from sensory and other areas of the cortex were channeled through a microchip, which, the scientists say, dispatched the same signals the hippocampus would have sent. A demonstration that an artificial device mimicked hippocampal output would mark a step toward deducing the underlying code that could be used to create a memory in the motor cortex—and perhaps one day to unravel ciphers for even higher-level behaviors.

If the codes for the sentence “See Spot run”—or perhaps an entire technical manual—could be ascertained, it might, in theory, be possible to input them directly to an electrode array in the hippocampus (or cortical areas), evoking the scene in The Matrix in which instructions for flying a helicopter are downloaded by cell phone. Artificial hippocampus research postulates a scenario only slightly more prosaic. “The kinds of examples [the U.S. Department of Defense] likes to typically use are coded information for flying an F-15,” says Berger.

The seeming simplicity of the model of neural input envisaged by artificial hippocampus-related studies may raise more questions than it answers. Would such an implant overwrite existing memories? Would the code for the sentence “See Spot run” be the same for me as it is for you or, for that matter, a native Kurdish speaker? Would the hippocampal codes merge cleanly with other circuitry that provides the appropriate context, a semantic framework, for the sentence? Would “See Spot run” be misinterpreted as a laundry mishap instead of a trotting dog?

Some neuroscientists think the language of the brain may not be deciphered until understanding moves beyond the reading of mere voltage spikes. “Just getting a lot of signals and trying to understand what these signals mean and correlating them with particular behavior is not going to solve it,” notes Henry Markram, director of neuroscience and technology at the Swiss Federal Institute of Technology in Lausanne. A given input into a neuron or groups of neurons can produce a particular output—conversion of sensory inputs to long-term memory by the hippocampus, for instance—through many different pathways. “As long as there are lots of different ways to do it, you’re not even close,” he says.

The Blue Brain Project, which Markram heads, is an attempt that began in 2005 to use supercomputer-based simulations to reverse-engineer the brain at the molecular and cellular levels—modeling first the simpler rat organ and then the human version to unravel the underlying function of neural processes. The latter task awaits a computer that boasts a more than 1,000-fold improvement over the processing power of current supercomputers. The actual code, when it does emerge, may be structured very differently from what appears in today’s textbooks. “I think there will be a conceptual breakthrough that will have significant implications for how we think of reality,” Markram says. “It will be quite a profound thing. That’s probably why it’s such an intractable problem.”

The challenge involved in figuring out how to move information into the brain suggests a practical foreseeable limit for how far neurotechnology might be advanced. The task of forming the multitude of connections that make a memory is vastly different from magnetizing a set of bits on a hard disk. “Complex information like the contents of a book would require the interactions of a very large number of brain cells over a very large area of the nervous system,” observes neuroscientist John P. Donoghue of Brown University. “Therefore, you couldn’t address all of them, getting them to store in their connections the correct kind of information. So I would say based on current knowledge, it’s not possible.”

Writing to the brain may remain a dream lost in cyberspace. But the seeming impossibility does not make Donoghue less sanguine about ultimate expectations for feeding information the other way and developing brain-controlled prostheses for the severely disabled. He has been a leader in studies to implant an array of multiple electrodes into the brain that can furnish a direct line from the cortex to a prosthetic arm or even a wheelchair.

Donoghue predicts that in the next five years brain-machine interfaces will let a paralyzed person pick up a cup and take a drink of water and that, in some distant future, these systems might be further refined so that a person with an upper spinal cord injury might accomplish the unthinkable, perhaps even playing a game of basketball with prosthetics that would make a reality of The Six Million Dollar Man, the 1970s television series. Even without an information pipeline into the brain, disabled patients and basic researchers might still reap the benefits of lesser substitutes. Gert Pfurtscheller of the Graz University of Technology in Austria and his colleagues reported last year on a patient with a spinal cord injury who was able, merely by thinking, to traverse a virtual environment, moving from one end to the other of a simulated street. Duke University’s Miguel A. L. Nicolelis, another pioneer in brain-machine interfaces, has begun to explore how monkeys connected to brain-controlled prosthetic devices begin to develop a kinesthetic awareness, a sense of movement and touch, that is completely separate from sensory inputs into their biological bodies. “There’s some physiological evidence that during the experiment they feel more connected to the robots than to their own bodies,” he says.

The most important consequences of these investigations may be something other than neural implants and robotic arms. An understanding of central nervous system development acquired by the Blue Brain Project or another simulation may let educators understand the best ways to teach children and determine at what point a given pedagogical technique should be applied. “You can build an educational development program that is engineered to, in the shortest possible time, allow you to acquire certain capabilities,” Markram says. If he is right, research on neural implants and brain simulations will produce more meaningful practical benefits than dreams of the brain as a flash drive drawn from 20th-century science-fiction literature.

Note: This article was originally published with the title, "Jacking Into the Brain".

Tuesday, November 11, 2008

WW II vet held in Nazi slave camp breaks silence: 'Let it be known'

* World War II vet held in slave camp witnessed Nazi atrocities first-hand
* Anthony Acevedo, 84, was one of 350 U.S. soldiers held at Buchenwald subcamp
* Only about 165 survived captivity and their subsequent death march, he says
* Survivors signed documents never to speak; Acevedo says now people "must know"

By Wayne Drash, Thelma Gutierrez and Sara Weisfeldt

LOMA LINDA, California (CNN) -- Anthony Acevedo thumbs through the worn, yellowed pages of his diary emblazoned with the words "A Wartime Log" on its cover. It's a catalog of deaths and atrocities he says were carried out on U.S. soldiers held by Nazis at a slave labor camp during World War II -- a largely forgotten legacy of the war.

Acevedo pauses when he comes across a soldier with the last name of Vogel.

"He died in my arms. He wouldn't eat. He didn't want to eat," says Acevedo, now 84 years old. "He said, 'I want to die! I want to die! I want to die!' "

The memories are still fresh, some 60 years later. Acevedo keeps reading his entries, scrawled on the pages with a Schaeffer fountain pen he held dear. See inside Acevedo's diary »

He was one of 350 U.S. soldiers held at Berga am Elster, a satellite camp of the Nazis' notorious Buchenwald concentration camp. The soldiers, working 12-hour days, were used by the German army to dig tunnels and hide equipment in the final weeks of the war. Less than half of the soldiers survived their captivity and a subsequent death march, he says.

Acevedo shows few emotions as he scans the pages of his diary. But when he gets to one of his final entries, the decades of pent-up pain, the horror witnessed by a 20-year-old medic, are too much.

"We were liberated today, April the 23, 1945," he reads.

His body shakes, and he begins sobbing. "Sorry," he says, tears rolling down his face. "I'm sorry." VideoWatch Acevedo's emotional account of being freed »

Acevedo's story is one that was never supposed to be told. "We had to sign an affidavit ... [saying] we never went through what we went through. We weren't supposed to say a word," he says.

The U.S. Army Center of Military History provided CNN a copy of the document signed by soldiers at the camp before they were sent back home. "You must be particularly on your guard with persons representing the press," it says. "You must give no account of your experience in books, newspapers, periodicals, or in broadcasts or in lectures."

The document ends with: "I understand that disclosure to anyone else will make me liable to disciplinary action."

The information was kept secret "to protect escape and evasion techniques and the names of personnel who helped POW escapees," said Frank Shirer, the chief historian at the U.S. Army Center for Military History.

Acevedo sees it differently. For a soldier who survived one of the worst atrocities of mankind, the military's reaction is still painful to accept. "My stomach turned to acid, and the government didn't care. They didn't give a hullabaloo."

It took more than 50 years, he says, before he received 100 percent disability benefits from the U.S. Department of Veterans Affairs.

Despite everything Acevedo endured during the war, little had prepared him for his own father's attitude toward his capture. "My dad told me I was a coward," he says.

"I turned around and got my duffel bag, my luggage, and said, 'This is it, Father. I'm not coming back.' So I took the train the following day, and I didn't see my parents for years, because I didn't want to see them. I felt belittled."

For decades, Acevedo followed the rules and kept his mouth shut. His four children didn't know the extent of his war experience. He says he felt stymied because of the document he signed. "You never gave it a thought because of that paper."

Now, he says it's too important to be forgotten. In recent years, he's attended local high schools to tell his story to today's generation.

"Let it be known," he says. "People have to know what happened."

Born July 31, 1924, in San Bernardino, California, Anthony C. Acevedo is what is known in today's parlance as a "citizen child" -- one who was born in the United States to parents from Mexico. iReport: Tell us your war stories

A Mexican-American, he was schooled in Pasadena, California, but couldn't attend the same classes as his white peers. "We couldn't mix with white people," he says. Both of his parents were deported to Mexico in 1937, and he went with them.

Acevedo returned to the States when he was 17, he says, because he wanted to enlist in the U.S. Army. He received medical training in Illinois before being sent to the European theater.

A corporal, he served as a medic for the 275th Infantry Regiment of the 70th Infantry Division. Acevedo was captured at the Battle of the Bulge after days of brutal firefights with Nazis who surrounded them. He recalls seeing another medic, Murry Pruzan, being gunned down.

"When I saw him stretched out there in the snow, frozen," Acevedo says, shaking his head. "God, that's the only time I cried when I saw him. He was stretched out, just massacred by a machine gun with his Red Cross band."

He pauses. "You see all of them dying out there in the fields. You have to build a thick wall."

Acevedo was initially taken to a prison camp known as Stalag IX-B in Bad Orb, Germany, where thousands of American, French, Italian and Russian soldiers were held as prisoners of war. Acevedo's diary entry reads simply: "Was captured the 6th of January 1945."

For the next several months, he would be known by the Germans only as Prisoner Number 27016. One day while in Stalag IX-B, he says, a German commander gathered American soldiers and asked all Jews "to take one step forward." Few willingly did so. VideoWatch Acevedo describe being selected as an "undesirable" »

Jewish soldiers wearing Star of David necklaces began yanking them off, he says. About 90 Jewish soldiers and another 260 U.S. soldiers deemed "undesirables" -- those who "looked like Jews" -- were selected. Acevedo, who is not Jewish, was among them.

They were told they were being sent to "a beautiful camp" with a theater and live shows.

"It turned out to be the opposite," he says. "They put us on a train, and we traveled six days and six nights. It was a boxcar that would fit heads of cattle. They had us 80 to a boxcar. You couldn't squat. And there was little tiny windows that you could barely see through."

It was February 8, 1945, when they arrived. The new camp was known as Berga am Elster, a subcamp of Buchenwald, the Nazi concentration camp where tens of thousands of Jews and other political prisoners were killed under Adolf Hitler's regime. PhotoSee the horrors of Buchenwald »

Acevedo says he was one of six medics among the 350 U.S. soldiers at Berga. Political prisoners from other countries were held at Berga separate from the Americans. "We didn't mingle with them at all," he says, adding that the U.S. soldiers worked in the same tunnels as the other political prisoners.

"We were all just thin as a rail."

The U.S. prisoners, Acevedo says, were given 100 grams of bread per week made of redwood sawdust, ground glass and barley. Soup was made from cats and rats, he says. Eating dandelion leaves was considered a "gourmet meal."

If soldiers tried to escape, they would be shot and killed. If they were captured alive, they would be executed with gunshots to their foreheads, Acevedo says. Wooden bullets, he says, were used to shatter the inside of their brains. Medics were always asked to fill the execution holes with wax, he says.

"Prisoners were being murdered and tortured by the Nazis. Many of our men died, and I tried keeping track of who they were and how they died."

The soldiers were forced to sleep naked, two to a bunk, with no blankets. As the days and weeks progressed, his diary catalogs it all. The names, prisoner numbers and causes of death are listed by the dozens in his diary. He felt it was his duty as a medic to keep track of everyone.

"I'm glad I did it," he says.

As a medic, he says, he heard of other more horrific atrocities committed by the Nazis at camps around them. "We heard about experiments that they were doing -- peeling the skins of people, humans, political prisoners, making lampshades." VideoWatch Acevedo talk about Nazi atrocities »

He and the other soldiers were once taken to what Acevedo believes was the main camp of Buchenwald, about 30 miles (48 kilometers) from Berga. They noticed large pipes coming from one building.

"We thought we were going to be gassed when we were told to take our clothes off," he says. "We were scared. We were stripped."

"Rumors were around that this was where the political prisoners would be suffocated with gas." It turned out to be a shower, the only time during their captivity they were allowed to bathe.

The main Buchenwald camp was officially liberated on April 11, 1945. But the camp and its subcamps were emptied of tens of thousands of prisoners as American troops neared. The U.S. troops held at the Berga compound were no exception.

"Very definite that we are moving away from here and on foot. This isn't very good for our sick men. No drinking water and no latrines," Acevedo wrote in his diary on April 4, 1945.

He says they began a death march of 217 miles (349 kilometers) that would last three weeks. More than 300 U.S. soldiers were alive at the start of the march, he says; about 165 were left by the end, when they were finally liberated.

Lines of political prisoners in front of them during the march caught the full brunt of angry Nazi soldiers.

"We saw massacres of people being slaughtered off the highway. Women, children," he says. "You could see people of all ages, hanging on barbed wire."

One of his diary entries exemplifies an extraordinary patriotism among soldiers, even as they were being marched to their deaths. "Bad news for us. President Roosevelt's death. We all felt bad about it. We held a prayer service for the repose of his soul," Acevedo wrote on April 13, 1945.

It adds, "Burdeski died today."

To this day, Acevedo still remembers that soldier. He wanted to perform a tracheotomy using his diary pen to save Burdeski, a 41-year-old father of six children. A German commander struck Acevedo in the jaw with a rifle when he asked.

"I'll never forget," he says.

On a recent day, about a dozen prisoners of war held during World War II and their liberators gathered at the Jerry L. Pettis Memorial Veterans Medical Center in Loma Linda, California. Many applauded Acevedo for his heroics.

"Those of us in combat have our own heroes, and those are the medics. And that's Antonio. Thank you, Antonio," one of the men said.

The men gathered there nodded their heads. Two stood to shake Acevedo's hand.

"The people that are in this room really are an endangered species," another man said. "When they're gone, they're gone. ... That is why they should be honored and put in history for generations to come, because there are not that many of them left."

Donald George sat next to Acevedo. The two were captured about a half-mile apart during the Battle of the Bulge. "It's hard to explain how it is to be sitting with a bunch of people that you know they've been through the same thing you've been through," George said.

"Some of us want to talk about it, and some of us don't. Some of us want to cry about it once in a while, and some of us won't. But it's all there," he said.

"We still like to come and be together a couple times a month," George added, before Acevedo finished his sentence: "To exchange what you are holding back inside."

Acevedo says the world must never forget the atrocities of World War II and that for killing 6 million Jews, Hitler was the worst terrorist of all time. He doesn't want the world to ever slide backward.

His message on this Veterans Day, he says, is never to hold animosity toward anybody.

"You only live once. Let's keep trucking. If we don't do that, who's going to do it for us? We have to be happy. Why hate?" he says. "The world is full of hate, and yet they don't know what they want."

Thursday, November 6, 2008

Why Do We Forget Things?

The brain can store a vast number of memories, so why can't we find these memories when we need to? A new study provides insights into this question.

By Edward K. Vogel and Trafton Drew

Our brains are crammed with a massive amount of memories that we have formed over a lifetime of experiences. These memories range from the profound (who am I and how did I get here?) to the most trivial (the license plate of the car at a stoplight). Furthermore, our memories also vary considerably in their precision. Parents, for instance, often know the perils of a fuzzy memory when shopping for a birthday gift for their child: remembering that their son wanted the G.I. Joe with Kung Fu Grip rather than the regular G.I. Joe could make an enormous difference in how well the gift is received. Thus, the “fuzziness” of our memory can often be just as important in our daily lives as being able to remember lots and lots of information in the first place.

Different Levels of Detail for Different Types of Memory?
In the past several decades, cognitive psychologists have determined that there are two primary memory systems in the human mind: a short-term, or “working,” memory that temporarily holds information about just a few things that we are currently thinking about; and a long-lasting memory that can hold massive amounts of information gained through a lifetime of thoughts and experiences. These two memory systems are also thought to differ in the level of detail they provide: working memory provides sharp detail about the few things we are presently thinking about, whereas long-term memory provides a much fuzzier picture about lots of different things we have seen or experienced. That is, although we can hold lots of things in long-term memory, the details of the memory aren’t always crystal-clear and are often limited to just the gist of what we saw or what happened.

A recently published study by Timothy F. Brady, a cognitive neuroscientist at the Massachusetts Institute of Technology, and colleagues suggests that these long-term memories may not be nearly as fuzzy as once thought, however. In their work, the researchers asked subjects to try to remember 3,000 pictures of common objects—including items such as backpacks, remote controls and toasters—that were presented one at a time for just a few seconds each. At the end of this viewing phase, the researchers tested subjects’ memory for each object by showing them two objects and asking which one they had seen before. Not surprisingly, subjects were exceptionally good (more than 90 percent correct) even though there were thousands of objects to remember. This high success rate attests to the massive storage ability of long-term memory. What was most surprising, however, was the amazing level of detail that the subjects had for all of these memories. The subjects were just as good at telling the difference between two pictures of the same object even when the objects differed in an extremely subtle manner, such as a pair of toasters with slightly different slices of bread.

If It’s Not Fuzzy, Why Do We Still Forget Things?
This new work provides compelling evidence that the enormous amount of information we hold in long-term memory is not so uncertain after all. It seems that we actually hold representations of things we’ve seen in a fairly detailed and precise form.

Of course, this finding raises the obvious question: if our memories aren’t all that fuzzy, then why do we often forget the details of things we want to remember? One explanation is that, although the brain contains detailed representations of lots of different events and objects, we can’t always find that information when we want it. As this study reveals, if we’re shown an object, we can often be very accurate and precise at being able to say whether we’ve seen it before. If we’re in a toy store and trying to remember what it was that our son wanted for his birthday, however, we need to be able to voluntarily search our memory for the right answer—without being prompted by a visual reminder. It seems that it is this voluntary searching mechanism that’s prone to interference and forgetfulness. At least that’s our story when we come home without the Kung Fu Grip G.I. Joe.

Are you a scientist? Have you recently read a peer-reviewed paper that you want to write about? Then contact Mind Matters editor Jonah Lehrer, the science writer behind the blog The Frontal Cortex and the book Proust Was a Neuroscientist.