10 Mind-Boggling Psychiatric Treatments

Nobody ever claimed a visit to the doctor was a pleasant way to pass the time. But if you’re timid about diving onto a psychiatrist’s couch or paranoid about popping pills, remember: It could be worse. Like getting-a-hole-drilled-into-your-skull worse. Or having-a-doctor-infect-you-with-malaria-to-cure-you worse. Think of it this way. After finding out what’s not going to happen to you, that couch is going to start looking a lot more comfortable.

1) INSULIN-COMA THERAPY

The coma-therapy trend began in 1927. Viennese physician Manfred Sakel accidentally gave one of his diabetic patients an insulin overdose, and it sent her into a coma. But what could have been a major medical faux pas turned into a triumph. The woman, a drug addict, woke up and declared her morphine craving gone. Then Sakel (who really isn’t earning our trust here) made the same mistake with another patient, who also woke up claiming to be cured.

Before long, Sakel was intentionally testing the therapy with other patients and reporting a 90 percent recovery rate, particularly among schizophrenics. Strangely, however, Sakel’s treatment success remains a mystery. Presumably, a big dose of insulin causes blood sugar levels to plummet, which starves the brain of food and sends the patient into a coma. But why this unconscious state would help psychiatric patients is anyone’s guess.

Regardless, the popularity of insulin therapy faded, mainly because it was dangerous. Slipping into a coma is no walk in the park, and between one and two percent of treated patients died as a result.

2) TREPANATION

Ancient life was not without its hazards. Between wars, drunken duels, and the occasional run-in with an inadequately domesticated pig, it’s no surprise that archaic skulls tend to have big holes in them.

But not all holes are created with equal abandon. Through the years, archaeologists have uncovered skulls marked by a carefully cut circular gap, which shows signs of being made long before the owner of the head passed away. These fractures were no accident; they were the result one of the earliest forms of psychiatric treatment called trepanation .

The basic theory behind this "therapy" holds that insanity is caused by demons lurking inside the skull. Boring a hole in the patient’s head creates a door through which the demons can escape, and - viola! - out goes the crazy. Despite the peculiarity of the theory and lack of major-league anesthetics, trepanation was by no means a limited phenomenon. From the Neolithic era to the early 20th century, cultures all over the world used it was way to cure patients of their ills.

Doctors eventually phased out the practice as less, er, invasive procedures were developed. Average Joes, on the other hand, didn’t follow suit. Trepanation patrons still exist. In fact, they even have their own organizations - and websites! Check out the International Trepanation Advocacy Group at www.trepan.com if you’re still curious.

3) ROTATIONAL THERAPY

Charles Darwin’s grandfather Erasmus Darwin was a physician, philosopher, and scientist, but he wasn’t particularly adept at any of the three. Consequently, his ideas weren’t always taken seriously. Of course, this could be because he liked to record them in bad poetic verse (sample: "By immutable immortal laws / Impress’d in Nature by the great first cause, / Say, Muse! How rose from elemental strife / Organic forms, and kindled into life"). It could also be because his theories were a bit far-fetched, such as his spinning-couch treatment.

Darwin’s logic was that sleep could cure disease and that spinning around really fast a great way to induce the slumber. Nobody paid much attention to it at first, but later, American physician Benjamin Rush adapted the treatment for psychiatric purposes. He believed that spinning would reduce brain congestion and, in turn cure mental illness. He was wrong. Instead, Rush just ended up with dizzy patients who were still crazy. These days, rotating chairs are limited to the study of vertigo and space sickness.

4) HYDROTHERAPY

If the word "hydrotherapy" conjures up images of Hollywood stars lazily soaking in rich, scented baths, then you probably weren’t an early 20th-centruy mental patient.

Building off the idea that a dip in the water is often calming, psychiatrists of yore attempted to remedy various symptoms with corresponding liquid treatments. For instance, hyperactive patients got warm, tiring baths, while lethargic patients received stimulating sprays. Some doctors, however, got a bit too zealous about the idea, prescribing therapies that sounded more like punishment than panacea. One treatment involved mummifying the patient in towels soaked in ice-cold water. Another required the patient to remain continuously submerged in a bath for hours even days-which might not sound so bad, except they were strapped in and only allowed out to use the restroom.

Finally, some doctors ordered the use of high-pressure jets. Sources indicate that at least one patient was strapped to the wall in the crucification position (never a good sign) and blasted with water from a fire hose. Like many extreme treatments, hydrotherapy was eventually replaced with psychiatric drugs, which tended to be more effective - and more pleasant.

5) MESMERISM

Much like Yoda, Austrian physician Franz Mesmer (1734-1815) believed that an invisible force pervaded everything in existence, and that disruptions in this force caused pain and suffering. But Mesmer’s ideas would have been of little use to Luke Skywalker. His basic theory was that the gravity of the moon affected the body’s fluids in much the same way it caused ocean tides, and that some diseases accordingly waxed and waned with the phases of the moon. The dilemma, then, was to uncover what could be done about gravity’s pernicious effects. Mesmer’s solution: use magnets.

After all, gravity and magnetism were both about objects being attracted to each other. Thus, placing magnets on certain areas of a patient’s body might be able to counteract the disruptive influence of the moon’s gravity and restore the normal flow of bodily fluids. Surprisingly, many patients praised the treatment as a miracle cure, but the medical community dismissed it as supposititious hooey and chalked up his treatment successes to the placebo effect.

Mesmer and his theories were ultimately discredited, but he still left his mark. Today, he’s considered the father of modern hypnosis because of his inadvertent discovery of the power of suggestion, and his name lives on in the English word "mesmerize."

6) MALARIA THERAPY

Ah, if only we’re talking about about a therapy for malaria. Instead, this is malaria as therapy-specifically, as a treatment for syphilis. There was no cure for the STD until the early 1900s, when Viennese neurologist Wagner von Jauregg got the idea to treat syphilis sufferers with malaria-infected blood. Predictably, these patients would develop the disease, which would cause an extremely high fever that would kill the syphilis bacteria. Once that happened, they were given the malaria drug quinine, cured and sent home happy and healthy.

The treatment did have its share of side effects -that nasty sustained fever, for one - but it worked and it was a whole lot better than dying. In fact, Von Jauregg won the Nobel Prize for malaria therapy, and the treatment remained in use until the development of penicillin came along and gave doctors a better, safer way to sure the STD.

7) CHEMICALLY INDUCED SEIZURES

Nobody ever said doctors had flawless logic. A good example: seizure therapy. Hungarian pathologist Ladislas von Meduna pioneered the idea. He reasoned that, because schizophrenia was rare in epileptics, and because epileptics seemed blissfully happy after seizures, then giving schizophrenics seizures would make them calmer.

In order to do this von Meduna tested numerous seizure-inducing drugs (including such fun candidates as strychnine, caffeine, and absinthe) before settling on metrazol, a chemical that stimulates the circulatory and respiratory systems. And although he claimed the treatment cured the majority of his patients, opponents argues that the method was dangerous and poorly understood.

To this day, no one is quite clear on why seizures can help ease some schizophrenic symptoms, but many scientists believe the convulsions release chemicals otherwise lacking in patient’s brains. Ultimately, the side effects (including fractured bones and memory loss) turned away both doctors and patients.

8) HYSTERIA THERAPY

Once upon a time, women suffering from pretty much any type of mental illness were lumped together as victims of hysteria. The Greek physician Hippocrates popularized the term, believing hysteria encompassed conditions ranging from nervousness to fainting fits to spontaneous muteness. The root cause, according to him, was a wandering womb.

So, whither does it wander? Curious about Hippocrates’ theory, Plato asked himself that very question. He claimed that is the uterus "remains unfruitful long beyond its proper time, it gets discontented and angry and wanders in every direction through the body, closes up the passages of breath, and, by obstructing respiration, drives women to extremity."

Consequently, cures for hysteria involved finding a way to "calm down" the uterus. And while there was no dearth of methods for doing this (including holding foul-smelling substances under the patient’s nose to drive the uterus away from the chest), Plato believed that the only sure-fire way to solve the problem was to get married and have babies. After all, the uterus always ended up in the right place when it came time to bear a child.

Although "womb-calming" as psychiatric treatment died out long ago, hysteria as a diagnosis hung around until the 20th century, when doctors began identifying conditions such as depression, post-traumatic stress disorder, and phobias.

9) PHRENOLOGY

Around the turn of the 19th century, German physician Franz Gall developed phrenology, a practice based on the idea that people’s personalities are depicted in the bumps and depressions of their skulls.

Basically, Gall believed that the parts of the brain a person used more often would get bigger, like muscles. Consequently, these pumped-up areas would take up more skull space, leaving visible bumps in those places on your head. Gall then tried to determine which parts of the skull corresponded to which traits. For instance, bumps over the ears meant you were destructive; a ridge at the top of the head indicated benevolence; and thick folds on the back of the neck were signs of a sexually oriented personality.

In the end, phrenologists did little to make their mark in the medical field, as they couldn’t treat personality issues, only diagnose them (and inaccurately, at that). By the early 1900s, the fad had waned, and modern neuroscience had garnered dominion over the brain.

10) LOBOTOMY

Everybody’s favorite psychiatric treatment, the modern lobotomy was the brainchild of Egas Moniz, a Portuguese doctor. Moniz believed that mental illness were generally caused by problems in the neurons of the frontal lobe, the part of the brain just behind the forehead. So when he heard about a monkey whose violent, feces-throwing urges had been curbed by cute to the frontal lobe, Moniz was moved to try out the same thing on his patients. (The lobe-cutting, not the feces-throwing.) He believed the technique could cure insanity while leaving the rest of the patient’s mental function relatively normal, and his (admittedly fuzzy) research seemed to support that.

The accolades flooded in, and (in one of the lower points in the Karolinska Institute’s history) Moniz was awarded the Nobel Prize in 1949.

After the lobotomy rage hit American shores, Dr. Walter Freeman took to traveling the country in his "lobotomobile" (no, really), performing the technique on everyone from catatonic schizophrenics to disaffected housewives. His road-ready procedure involved inserting a small ice pick into the brain through the eye socket and wiggling it around a bit.

While some doctors thought he’s found a way to save hopeless cases from the horrors of life-long institutionalization, others noted that Freeman didn’t bother with sterile techniques, had no surgical training whatsoever, and tended to be a bit imprecise when describing his patient’s recovery.

As the number of lobotomies increased, a major problem became apparent. The patients weren’t just calm; they were virtual zombies who scarcely responded to the world around them. Between that and the bad press received in films and novels such as One Flew Over the Cuckoo’s Nest, the treatment soon fell out of favor.

Bonus: Father Hell Hath No Fury Like a Therapist Scorned

In the end, all 10 of these psychiatric treatments came under fire from critics and were shunned by the medical community. And the physicians involved usually went down with them. But not Franz Mesmer, the man behind mesmerism (see entry #5). He wasn’t going out without a fight - several, actually.

Mesmer’s career was plagued by various opponents, one of whom was a priest named Father Hell (Don’t worry. We had the name fact-checked, twice). Apparently, the good Maximilian Hell tried to take credit for Mesmer’s magnet-based psychiatric treatment. In response, a furious Mesmer replied by writing a dissertation explaining that the idea was his first. Unfortunately for Mesmer’s argument, he plagiarized much of said dissertation.

In the end, though, it didn’t matter much. Mesmer abandoned the practice in favor of his own personal magnetism. Somewhere along the way, he’d noticed that he could obtain equally good results by simply placing his hands on a patient’s affected body part and concluded that he himself must be giving off magnetic energy.

Many people, including Father Hell, worried about a placebo effect, and controversy erupted once again. And again, Mesmer took great offense to his critics and defended his practices vehemently.

At one point, he even wrote an open letter to Marie Antoinette that belittled the Austrian royal family. Bad move. This prompted an irritated Louis XVI to appoint two commissions to investigate the magnetism fad. (For the record, members included Benjamin Franklin and Dr. Joseph Guillotin, after whom the guillotine was named.) One report concluded that Mesmer’s results were likely attributable to the power of suggestion. That would’ve been bad enough, but another, confidential, report insinuated that Mesmer had a particular fondness for laying his hands on the bodies of young and beautiful women.

Top 10 Unsolved Mysteries of the Brain

Of all the objects in the universe, the human brain is the most complex: There are as many neurons in the brain as there are stars in the Milky Way galaxy. So it is no surprise that, despite the glow from recent advances in the science of the brain and mind, we still find ourselves squinting in the dark somewhat.

But we are at least beginning to grasp the crucial mysteries of neuroscience and starting to make headway in addressing them. Even partial answers to these 10 questions could restructure our understanding of the roughly three-pound mass of gray and white matter that defines who we are.

1. How is information coded in neural activity?

Neurons, the specialized cells of the brain, can produce brief spikes of voltage in their outer membranes. These electrical pulses travel along specialized extensions called axons to cause the release of chemical signals elsewhere in the brain. The binary, all-or-nothing spikes appear to carry information about the world: What do I see? Am I hungry? Which way should I turn? But what is the code of these millisecond bits of voltage? Spikes may mean different things at different places and times in the brain. In parts of the central nervous system (the brain and spinal cord), the rate of spiking often correlates with clearly definable external features, like the presence of a color or a face. In the peripheral nervous system, more spikes indicates more heat, a louder sound, or a stronger muscle contraction.

As we delve deeper into the brain, however, we find populations of neurons involved in more complex phenomena, like reminiscence, value judgments, simulation of possible futures, the desire for a mate, and so on—and here the signals become difficult to decrypt. The challenge is something like popping the cover off a computer, measuring a few transistors chattering between high and low voltage, and trying to guess the content of the Web page being surfed.

It is likely that mental information is stored not in single cells but in populations of cells and patterns of their activity. However, it is currently not clear how to know which neurons belong to a particular group; worse still, current technologies (like sticking fine electrodes directly into the brain) are not well suited to measuring several thousand neurons at once. Nor is it simple to monitor the connections of even one neuron: A typical neuron in the cortex receives input from some 10,000 other neurons.

Although traveling bursts of voltage can carry signals across the brain quickly, those electrical spikes may not be the only—or even the main—way that information is carried in nervous systems. ­Forward-looking studies are examining other possible information couriers: glial cells (poorly understood brain cells that are 10 times as common as neurons), other kinds of signaling mechanisms between cells (such as newly discovered gases and peptides), and the biochemical cascades that take place inside cells.

2. How are memories stored and retrieved?

When you learn a new fact, like someone’s name, there are physical changes in the structure of your brain. But we don’t yet comprehend exactly what those changes are, how they are orchestrated across vast seas of synapses and neurons, how they embody knowledge, or how they are read out decades later for retrieval.

One complication is that there are many kinds of memories. The brain seems to distinguish short-term memory (remembering a phone number just long enough to dial it) from long-term memory (what you did on your last birthday). Within long-term memory, declarative memories (like names and facts) are distinct from non­declarative memories (riding a bicycle, being affected by a subliminal message), and within these general categories are numerous subtypes. Different brain structures seem to support different kinds of learning and memory; brain damage can lead to the loss of one type without disturbing the others.

Nonetheless, similar molecular mechanisms may be at work in these memory types. Almost all theories of memory propose that memory storage depends on synapses, the tiny connections between brain cells. When two cells are active at the same time, the connection between them strengthens; when they are not active at the same time, the connection weakens. Out of such synaptic changes emerges an association. Experience can, for example, fortify the connections between the smell of coffee, its taste, its color, and the feel of its warmth. Since the populations of neurons connected with each of these sensations are typically activated at the same time, the connections between them can cause all the sensory associations of coffee to be triggered by the smell alone.

But looking only at associations—and strengthened connections between neurons—may not be enough to explain memory. The great secret of memory is that it mostly encodes the relationships between things more than the details of the things themselves. When you memorize a melody, you encode the relationships between the notes, not the notes per se, which is why you can easily sing the song in a different key.

Memory retrieval is even more mysterious than storage. When I ask if you know Alex Ritchie, the answer is immediately obvious to you, and there is no good theory to explain how memory retrieval can happen so quickly. Moreover, the act of retrieval can destabilize the memory. When you recall a past event, the memory becomes temporarily susceptible to erasure. Some intriguing recent experiments show it is possible to chemically block memories from reforming during that window, suggesting new ethical questions that require careful consideration.

3. What does the baseline activity in the brain represent?

Neuroscientists have mostly studied changes in brain activity that correlate with stimuli we can present in the laboratory, such as a picture, a touch, or a sound. But the activity of the brain at rest—its “baseline” activity—may prove to be the most important aspect of our mental lives. The awake, resting brain uses 20 percent of the body’s total oxygen, even though it makes up only 2 percent of the body’s mass. Some of the baseline activity may represent the brain restructuring knowledge in the background, simulating future states and events, or manipulating memories. Most things we care about—reminiscences, emotions, drives, plans, and so on—can occur with no external stimulus and no overt output that can be measured.

One clue about baseline activity comes from neuroimaging experiments, which show that activity decreases in some brain areas just before a person performs a goal-directed task. The areas that decrease are the same regardless of the details of the task, hinting that these areas may run baseline programs during downtime, much as your computer might run a disk-defragmenting program only while the resources are not needed elsewhere.

In the traditional view of perception, information from the outside world pours into the senses, works its way through the brain, and makes itself consciously seen, heard, and felt. But many scientists are coming to think that sensory input may merely revise ongoing internal activity in the brain. Note, for example, that sensory input is superfluous for perception: When your eyes are closed during dreaming, you still enjoy rich visual experience. The awake state may be essentially the same as the dreaming state, only partially anchored by external stimuli. In this view, your conscious life is an awake dream.

4. How do brains simulate the future?

When a fire chief encounters a new blaze, he quickly makes predictions about how to best position his men. Running such simulations of the future—without the risk and expense of actually attempting them—allows “our hypotheses to die in our stead,” as philosopher Karl Popper put it. For this reason, the emulation of possible futures is one of the key businesses that intelligent brains invest in.

Yet we know little about how the brain’s future simulator works because traditional neuroscience technologies are best suited for correlating brain activity with explicit behaviors, not mental emulations. One idea suggests that the brain’s resources are devoted not only to processing stimuli and reacting to them (watching a ball come at you) but also to constructing an internal model of that outside world and extracting rules for how things tend to behave (knowing how balls move through the air). Internal models may play a role not only in motor acts, like catching, but also in perception. For example, vision draws on significant amounts of information in the brain, not just on input from the retina. Many neuroscientists have suggested over the past few decades that perception arises not simply by building up bits of data through a hierarchy but rather by matching incoming sensory data against internally generated expectations.

But how does a system learn to make good predictions about the world? It may be that memory exists only for this purpose. This is not a new idea: Two millennia ago, Aristotle and Galen emphasized memory as a tool in making successful predictions for the future. Even your memories about your life may come to be understood as a special subtype of emulation, one that is pinned down and thus likely to flow in a certain direction.

5. What are emotions?

We often talk about brains as information-processing systems, but any account of the brain that lacks an account of emotions, motivations, fears, and hopes is incomplete. Emotions are measurable physical responses to salient stimuli: the increased heartbeat and perspiration that accompany fear, the freezing response of a rat in the presence of a cat, or the extra muscle tension that accompanies anger. Feelings, on the other hand, are the subjective experiences that sometimes accompany these processes: the sensations of happiness, envy, sadness, and so on. Emotions seem to employ largely unconscious machinery—for example, brain areas involved in emotion will respond to angry faces that are briefly presented and then rapidly masked, even when subjects are unaware of having seen the face. Across cultures the expression of basic emotions is remarkably similar, and as Darwin observed, it is also similar across all mammals. There are even strong similarities in physiological responses among humans, reptiles, and birds when showing fear, anger, or parental love.

Modern views propose that emotions are brain states that quickly assign value to outcomes and provide a simple plan of action. Thus, emotion can be viewed as a type of computation, a rapid, automatic summary that initiates appropriate actions. When a bear is galloping toward you, the rising fear directs your brain to do the right things (determining an escape route) instead of all the other things it could be doing (rounding out your grocery list). When it comes to perception, you can spot an object more quickly if it is, say, a spider rather than a roll of tape. In the realm of memory, emotional events are laid down differently by a parallel memory system involving a brain area called the amygdala.

One goal of emotional neuroscience is to understand the nature of the many disorders of emotion, depression being the most common and costly. Impulsive aggression and violence are also thought to be consequences of faulty emotion regulation.

6. What is intelligence?

Intelligence comes in many forms, but it is not known what intelligence—in any of its guises—means biologically. How do billions of neurons work together to manipulate knowledge, simulate novel situations, and erase inconsequential information? What happens when two concepts “fit” together and you suddenly see a solution to a problem? What happens in your brain when it suddenly dawns on you that the killer in the movie is actually the unsuspected wife? Do intelligent people store knowledge in a way that is more distilled, more varied, or more easily retrievable?

We all grew up with the near-future promise of smart robots, but today we have little better than the Roomba robotic vacuum cleaner. What went wrong? There are two camps for explaining the weak performance of artificial intelligence: Either we do not know enough of the fundamental principles of brain function, or we have not simulated enough neurons working together. If the latter is true, that’s good news: Computation gets cheaper and faster each year, so we should not be far from enjoying life with Asimovian robots who can effectively tend our households. Yet most neuroscientists recognize how distant we are from that dream. Currently, our robots are little more intelligent than sea slugs, and even after decades of clever research, they can barely distinguish figures from a background at the skill level of an infant.

Recent experiments explore the possible relationship of intelligence to the capacity of short-term memory, the ability to quickly resolve cognitive conflict, or the ability to store stronger associations between facts; the results are not yet conclusive. Many other possibilities—better restructuring of stored information, more parallel processing, or superior emulation of possible futures—have not yet been probed by experiments.

Intelligence may not be underpinned by a single mechanism or a single neural area. Whatever intelligence is, it lies at the heart of what is special about Homo sapiens. Other species are hardwired to solve particular problems, while our ability to abstract allows us to solve an open-ended series of problems. This means that studies of intelligence in mice and monkeys may be barking up the wrong family tree.

7. How is time represented in the brain?

Hundred-yard dashes begin with a gunshot rather than a strobe light because your brain can react more quickly to a bang than to a flash. Yet as soon as we get outside the realm of motor reactions and into the realm of perception (what you report that you saw and heard), the story changes. When it comes to awareness, the brain goes through a good deal of trouble to synchronize incoming signals that are processed at very different speeds.

For example, snap your fingers in front of you. Although your auditory system processes information about the snap about 30 milliseconds faster than your visual system, the sight of your fingers and the sound of the snap seem simultaneous. Your brain is employing fancy editing tricks to make simultaneous events in the world feel simultaneous to you, even when the different senses processing the information would individually swear otherwise.

For a simple example of how your brain plays tricks with time, look in the mirror at your left eye. Now shift your gaze to your right eye. Your eye movements take time, of course, but you do not see your eyes move. It is as if the world instantly made the transition from one view to the next. What happened to that little gap in time? For that matter, what happens to the 80 milliseconds of darkness you should see every time you blink your eyes? Bottom line: Your notion of the smooth passage of time is a construction of the brain. Clarifying the picture of how the brain normally solves timing problems should give insight into what happens when temporal calibration goes wrong, as may happen in the brains of people with dyslexia. Sensory inputs that are out of sync also contribute to the risk of falls in elderly patients.

8. Why do brains sleep and dream?

One of the most astonishing aspects of our lives is that we spend a third of our time in the strange world of sleep. Newborn babies spend about twice that. It is inordinately difficult to remain awake for more than a full day-night cycle. In humans, continuous wakefulness of the nervous system results in mental derangement; rats deprived of sleep for 10 days die. All mammals sleep, reptiles and birds sleep, and voluntary breathers like dolphins sleep with one brain hemisphere dormant at a time. The evolutionary trend is clear, but the function of sleep is not.

The universality of sleep, even though it comes at the cost of time and leaves the sleeper relatively defenseless, suggests a deep importance. There is no universally agreed-upon answer, but there are at least three popular (and nonexclusive) guesses. The first is that sleep is restorative, saving and replenishing the body’s energy stores. However, the high neural activity during sleep suggests there is more to the story. A second theory proposes that sleep allows the brain to run simulations of fighting, problem solving, and other key actions before testing them out in the real world. A third theory—the one that enjoys the most evidence—is that sleep plays a critical role in learning and consolidating memories and in forgetting inconsequential details. In other words, sleep allows the brain to store away the important stuff and take out the neural trash.

Recently, the spotlight has focused on REM sleep as the most important phase for locking memories into long-term encoding. In one study, rats were trained to scurry around a track for a food reward. The researchers recorded activity in the neurons known as place cells, which showed distinct patterns of activity depending upon the rats’ location on the track. Later, while the rats dropped off into REM sleep, the recordings continued. During this sleep, the rats’ place cells often repeated the exact same pattern of activity that was seen when the animals ran. The correlation was so close, the researchers claimed, that as the animal “dreamed,” they could reconstruct where it would be on the track if it had been awake—and whether the animal was dreaming of running or standing still. The emerging idea is that information replayed during sleep might determine which events we remember later. Sleep, in this view, is akin to an off-line practice session. In several recent experiments, human subjects performing difficult tasks improved their scores between sessions on consecutive days, but not between sessions on the same day, implicating sleep in the learning process.

Understanding how sleeping and dreaming are changed by ­trauma, drugs, and disease—and how we might modulate our need for sleep—is a rich field to harvest for future clues.

9. How do the specialized systems of the brain integrate with one another?

To the naked eye, no part of the brain’s surface looks terribly different from any other part. But when we measure activity, we find that different types of information lurk in each region of the neural territory. Within vision, for example, separate areas process motion, edges, faces, and colors. The territory of the adult brain is as fractured as a map of the countries of the world.

Now that neuroscientists have a reasonable idea of how that territory is divided, we find ourselves looking at a strange assortment of brain networks involved with smell, hunger, pain, goal setting, temperature, prediction, and hundreds of other tasks. Despite their disparate functions, these systems seem to work together seamlessly. There are almost no good ideas about how this occurs.

Nor is it understood how the brain coordinates its systems so rapidly. The slow speed of spikes (they travel about one foot per second in axons that lack the insulating sheathing called myelin) is one hundred-millionth the speed of signal transmission in digital computers. Yet a human can recognize a friend almost instantaneously, while digital computers are slow—and usually unsuccessful—at face recognition. How can an organ with such slow parts operate so quickly? The usual answer is that the brain is a parallel processor, running many operations at the same time. This is almost certainly true, but what slows down parallel-processing digital computers is the next stage of operations, where results need to be compared and decided upon. Brains are amazingly fast at this. So while the brain’s ability to do parallel processing is impressive, its ability to rapidly synthesize those parallel processes into a single, behavior-guiding output is at least as significant. An animal running must go left or right around a tree; it cannot do both.

There is no special anatomical location in the brain where information from all the different systems converges; rather, the specialized areas all interconnect with one another, forming a network of parallel and recurring links. Somehow, our integrated image of the world emerges from this complex labyrinthine network of brain structures. Surprisingly little study has been done on large, loopy networks like the ones in the brain—probably in part because it is easier to think about brains as tidy assembly lines than as dynamic networks.

10. What is consciousness?

Think back to your first kiss. The experience of it may pop into your head instantly. Where was that memory before you became conscious of it? How was it stored in your brain before and after it came into consciousness? What is the difference between those states

An explanation of consciousness is one of the major unsolved problems of modern science. It may not turn out to be a single phenomenon; nonetheless, by way of a preliminary target, let’s think of it as the thing that flickers on when you wake up in the morning that was not there, in the exact same brain hardware, moments before.

Neuroscientists believe that consciousness emerges from the material stuff of the brain primarily because even very small changes to your brain (say, by drugs or disease) can powerfully alter your subjective experiences. The heart of the problem is that we do not yet know how to engineer pieces and parts such that the resulting machine has the kind of private subjective experience that you and I take for granted. If I give you all the Tinkertoys in the world and tell you to hook them up so that they form a conscious machine, good luck. We don’t have a theory yet of how to do this; we don’t even know what the theory will look like.

One of the traditional challenges to consciousness research is studying it experimentally. It is probable that at any moment some active neuronal processes correlate with consciousness, while others do not. The first challenge is to determine the difference between them. Some clever experiments are making at least a little headway. In one of these, subjects see an image of a house in one eye and, simultaneously, an image of a cow in the other. Instead of perceiving a house-cow mixture, people perceive only one of them. Then, after some random amount of time, they will believe they’re seeing the other, and they will continue to switch slowly back and forth. Yet nothing about the visual stimulus changes; only the conscious experience changes. This test allows investigators to probe which properties of neuronal activity correlate with the changes in subjective experience.

The mechanisms underlying consciousness could reside at any of a variety of physical levels: molecular, cellular, circuit, pathway, or some organizational level not yet described. The mechanisms might also be a product of interactions between these levels. One compelling but still speculative notion is that the massive feedback circuitry of the brain is essential to the production of consciousness.

In the near term, scientists are working to identify the areas of the brain that correlate with consciousness. Then comes the next step: understanding why they correlate. This is the so-called hard problem of neuroscience, and it lies at the outer limit of what material explanations will say about the experience of being human.

The Human Brain: Marvel or Mess?

Let others rhapsodize about the elegant design and astounding complexity of the human brain—the most complicated, most sophisticated entity in the known universe, as they say.

David Linden, a professor of neuroscience at Johns Hopkins University, doesn't see it that way. To him, the brain is a "cobbled-together mess."

Impressive in function, sure. But in its design the brain is "quirky, inefficient and bizarre... a weird agglomeration of ad hoc solutions that have accumulated throughout millions of years of evolutionary history," he argues in his new book, "The Accidental Mind," from Harvard University Press.

More than another salvo in the battle over whether biological structures are the products of supernatural design or biological evolution (though Linden has no doubt it's the latter), research on our brain's primitive foundation is cracking such puzzles as why we cannot tickle ourselves, why we are driven to spin narratives even in our dreams and why reptilian traits persist in our gray matter.

Just as the mouse brain is a lizard brain "with some extra stuff thrown on top," Linden writes, the human brain is essentially a mouse brain with extra toppings.

That's how we wound up with two vision systems. In amphibians, signals from the eye are processed in a region called the midbrain, which, for instance, guides a frog's tongue to insects in midair and enables us to duck as an errant fastball bears down on us. Our kludgy brain retains this primitive visual structure even though most signals from the eye are processed in the visual cortex, a newer addition. If the latter is damaged, patients typically say they cannot see a thing. Yet if asked to reach for an object, many of them can grab it on the first try. And if asked to judge the emotional expression on a face, they get it right more often than chance would predict—especially if that expression is anger.

They're not lying about being unable to see. In such "blindsight," people who have lost what most of us think of as vision are seeing with the amphibian visual system. But because the midbrain is not connected to higher cognitive regions, they have no conscious awareness of an object's location or a face's expression. Consciously, the world looks inky black. But unconsciously, signals from the midbrain are merrily zipping along to the amygdala (which assesses emotion) and the motor cortex (which makes the arm reach out).

Primitive brains control movement with the cerebellum. Tucked in the back of the brain, this structure also predicts what a movement will feel like, and sends inhibitory signals to the somatosensory cortex, which processes the sense of touch, telling it not to pay attention to expected sensations (such as the feeling of clothes against your skin or the earth beneath your soles). This is why you can't tickle yourself: the reptilian cerebellum has kept the sensation from registering in the feeling part of the brain. Failing to register feelings caused by your own movements claims another victim: your sense of how hard you are hitting someone. Hence, "but Mom, he hit me harder!"

Neurons have hardly changed from those of prehistoric jellyfish. "Slow, leaky, unreliable," as Linden calls them, they tend to drop the ball: at connections between neurons, signals have a 70 percent chance of sputtering out. To make sure enough signals do get through, the brain needs to be massively interconnected, its 100 billion neurons forming an estimated 500 trillion synapses.

This interconnectedness is far too great for our paltry 23,000 or so genes to specify. The developing brain therefore finishes its wiring out in the world (if they didn't, a baby's head wouldn't fit through the birth canal). Sensory feedback and experiences choreograph the dance of neurons during our long childhood, which is just another name for the period when the brain matures.

With modern parts atop old ones, the brain is like an iPod built around an eight-track cassette player. One reptilian legacy is that as our eyes sweep across the field of view, they make tiny jumps. At the points between where the eyes alight, what reaches the brain is blurry, so the visual cortex sees the neural equivalent of jump cuts. The brain nevertheless creates a coherent perception out of them, filling in the gaps of the jerky feed. What you see is continuous, smooth. But as often happens with kludges, the old components make their presence felt in newer systems, in this case taking a system that worked well in vision and enlisting it higher-order cognition. Determined to construct a seamless story from jumpy input, for instance, patients with amnesia will, when asked what they did yesterday, construct a story out of memory scraps.

It isn't only amnesiacs whose brains confabulate. There is no good reason why dreams, which consolidate memories, should take a narrative form. If they're filing away memories, we should just experience memory fragments as each is processed. The cortex's narrative drive, however, doesn't turn off during sleep. Like an iPod turning on that cassette player, the fill-in-the-gaps that works so well for jumpy eye movements takes the raw material of memory and weaves it into a coherent, if bizarre, story. The reptilian brain lives on.