Jayne Jubb

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Name that smell—if you can’t, it could be an indicator of a problem somewhere in your brain. New research suggests that scratch-and-sniff smell tests could become an easy and cheap way to detect signs of traumatic brain injury and neurodegenerative ailments.

Recent research found that a diminished sense of smell predicted frontal lobe damage in 231 soldiers who had suffered blast-related injuries on the battlefield. In the Department of Defense study led by Michael Xydakis of the Uniformed Services University of the Health Sciences, subjects with low scores on a smell test were three times as likely to show evidence of frontal lobe damage during brain imaging than those whose sense of smell was normal.

When the sense of smell is working properly, it acts as a matchmaker between odourant molecules in the air and memories stored in the brain. Those memories are not housed in a single place, but extend across many regions. Because different smell signals have to take a variety of paths to reach their destinations, arranging their travel requires a lot of coordination. This unique feature makes an individual’s ability to describe and verbally name an odour extremely challenging and cognitively demanding.

A damaged sense of smell, therefore, can indicate that the ability to make those connections has been hampered by disease, a lack of sleep or, as shown in Xydakis’s study, injury to the brain. The new results add to a growing understanding of the link between brain damage and an impaired sense of smell. Researchers have been working for years to use olfaction tests to track damage to the brain caused by neurodegenerative ailments such as Parkinson’s and Alzheimer’s diseases.

Kim Good, an associate professor in the psychiatry department at Dalhousie University in Nova Scotia, is currently recruiting subjects for a cohort study that aims to better understand the link between olfaction and Parkinson’s, which could improve early identification and intervention. Olfactory deficits are as common as tremor in Parkinson’s, and they help rule out other competing diagnoses.

Smell is also the first sense to be affected by Alzheimer’s, with the hallmark protein tangles of the disease appearing early in the olfactory bulb. Last January psychiatrist Davangere Devanand of Columbia University and his colleagues reported the results of a four-year-long cohort study in Manhattan, which found that scores on a multiple-choice scratch-and-sniff test in which participants had to identify 40 scents were good predictors of cognitive decline.

It’s not hard to imagine such exams becoming a routine part of primary care for older patients. The beauty of olfaction tests is that testing is easy and can be done in the family GP’s office.

Why Smell is Special

The unique characteristics of our sense of smell make sniff tests ideal for diagnosing brain injury. Here are some of the most interesting scientific findings about this unusual sense:

■ The adult brain can generate new neurons in the olfactory bulb, the brain region that processes smells. This area is one of just a few regions that continue to grow new neurons during adulthood.

■ Individuals vary in how they perceive odours and whether or not they can detect certain scents, and yet humans seem to universally enjoy the smell of vanilla.

■ Anosmia, a condition in which people completely lose their sense of smell, can be debilitating. Sufferers often report feeling disconnected from their surroundings, and many become severely depressed.

■ Romantic couples can unconsciously sense their partner’s emotional state from their sweat—and the longer they have lived together, the better they are at it.

■ Babies locate their mother’s nipples in part by learning a smell map of the breasts.

Have an enjoyable June, and take time to smell the flowers (unless you have hay fever…) !

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When neuroscientist George Koob proposed creating a vaccine for addiction 25 years ago, his colleagues thought he was wasting his time. The immune system evolved to prevent infections, not highs from illegal drugs. Prevailing wisdom holds that treating addiction requires months or years of psychotherapy to help addicts change their thought patterns, a difficult process that does not consistently work. But Koob, then at the Scripps Research Institute, wanted addicts to be able to see their doctor for a shot that could keep them from getting high when their motivation to stay clean waned.

His premise was simple. Vaccines against infectious diseases work by priming the body to produce antibodies that stick to the invading pathoge, preventing it from causing illness. Koob, who now directs the National Institute on Alcohol Abuse and Alcoholism, believed that the body could be duped into producing antibodies to drugs of abuse. The antibodies would biochemically block these drugs from creating a high, thereby eliminating the incentive to use them. Unlike traditional vaccines, howeever, this approach would aim to treat, rather than prevent, drug abuse.

More than two decades after Koob proposed his idea, scientists are finally making headway on affordable vaccines against addictive drugs. A vaccine for cocaine has seen success in early human trials, and one against heroin is making its way toward the clinic. A potential vaccine to combat methamphetamine addiction has shown promise in rodents.

Yet the approach is not without its critics. No addiction vaccine has proved effective in a largescale investigation in people, and the first such vaccine (for nicotine addiction) to be put to that test did not fare well. Because environmental factors are instrumental in perpetuating addiction, many experts argue that the problem is unlikely to succumb to a strictly biochemical attack. Still, for a disease that often stubbornly persists despite available treatments, vaccines could be an important addition to the toolbox.

Scourge of Their Lives

Nearly one in 12 Americans is addicted to illegal drugs, according to the latest data from the Substance Abuse and Mental Health Services Administration. The National Institute on Drug Abuse estimates that abuse of alcohol, tobacco and illicit drugs together cost the economy more than $600 billion a year.

Addictions remain difficult to treat. First a user generally heads to detox, during which addicts abstain from using a drug so that it is eliminated from the body. Patients in detox centers receive around-the-clock support to manage the often intense physical and psychiatric symptoms that accompany this process. After detox, some people spend weeks or months in rehabilitation at a live-in facility; others simply attend weekly outpatient psychotherapy either individually or in groups. They often have to rely on willpower and motivation to try to stay clean. The limits of this do-it-yourself approach to addiction treatment are reflected in abysmally high relapse rates, which range from 40 to 60 percent for cocaine, heroin and methamphetamines.

Most psychotherapies used to treat addiction help an addict reduce and resist his or her cravings by avoiding places and people linked to drug taking—their triggers—and developing support networks to help them kick the habit. In addition, doctors may prescribe medications such as methadone and buprenorphine for addiction to heroin and other opiates that reduce withdrawal symptoms and cravings and temper the high. But these medications do not completely eliminate cravings, and users may not remember to take them every day. Drugs that combat nicotine addiction are partially effective at best, and no medications exist for dependence on cocaine, methamphetamines or alcohol.

Thus, for many addicts, getting and staying clean seems like an impossible dream….

Sleeping Rats

Koob wanted to help people overcome this frustration by interfering with the biochemistry of drug taking. After a user injects, inhales or ingests a drug, it travels through the bloodstream and crosses the blood-brain barrier, a sheath of cells that lines brain capillaries and protects the brain from many toxic substances and other molecules in the bloodstream. Once inside the brain, molecules of the drug (or its metabolised products) bind to specific targets, setting off a series of chemical events that produce feelings of euphoria. Methadone treats heroin withdrawal and cravings—and can block its high—by acting at opiate receptors much more slowly and mildly than heroin. Koob wanted to intervene sooner, before a drug crossed the blood-brain barrier. So he decided to push the idea of the addiction vaccine.

Like an infectious disease vaccine, an addiction vaccine mobilises the immune system to fight a foreign substance. The vaccine trains the immune system to make antibodies that specifically target the “invader.” These antibodies will then rapidly kill the pathogen or deactivate the drug whenever they encounter it in the bloodstream. Because they act by sticking to a drug molecule, antidrug antibodies have the added benefit of creating a compound that is too big to cross the blood-brain barrier.

For scientists, the goal of the vaccine was to coax the immune system into responding to something that does not ordinarily provoke a reaction. Koob and Scripps medicinal chemist Kim Janda decided to attach the drug molecule—cocaine in this case—to a protein from a virus that does incite an immune reaction. This technique causes the immune system to react to the combination molecule, creating antibodies that will bind to various parts of it. Many of these antibodies will then also attach to a cocaine molecule when it enters the body alone. The vaccine thus prompts a subset of immune cells to build an arsenal against cocaine.

Next Koob, Janda and their colleagues injected their vaccine into rats immediately after the animals were exposed to cocaine. Ordinarily, when get high for the first time on a stimulant such as cocaine, they become hyperactive and restless; they fail to eat and stay awake for extended periods. In contrast, after these rats took a huge hit of cocaine they were able to fall asleep. The rats had become immune to the effects of cocaine.

Several other laboratories, including that of neuroscientist Thomas Kosten of the Baylor College of Medicine, also developed cocaine vaccines that proved effective in animals. Instead of using a viral protein, Kosten and his colleagues attached cocaine to a toxin produced by the bacterium that causes cholera. In 2002 the researchers gave 24 former cocaine users their vaccine to test its safety and to see whether it would trigger the hoped-for antibody production in people similar to those who might eventually receive the vaccine therapy. Although the treatment proved benign, it failed to produce high levels of antibodies in 25 to 30 percent of patients.

Booster Shots

In a larger follow-up study published in 2009, Kosten’s team injected 109 drug users either with the vaccine or with saline—and gave the participants four booster shots over the next 12 weeks to try to raise the percentage of those able to make adequate antibodies. The researchers also tested the addicts’ urine three times a week for 24 weeks for cocaine and other drugs and monitored the level of anticocaine antibodies in their bloodstream. Only 38 percent of the vaccine recipients had high levels of those antibodies, yet nearly all produced some antibodies, and as a group they were 22 percent less likely to have a cocaine-positive urine test than were those who received saline injections. In addition, those who produced large amounts of antibodies were significantly more likely to have cut their cocaine usage by half.

Still, Kosten’s vaccine left a considerable number of cocaine addicts without adequate antibody protection. It also did not affect their desire to use, which means that they might not come back for booster shots. So Koob and his colleagues kept pursuing their virus-based vaccine and came up with a combination of chemicals that included a new viral protein. In a study published in 2013 Crystal, Koob, Janda and their colleagues injected their latest manipulation of the cocaine molecule into four female rhesus macaques monkeys that had become dependent on cocaine; a fifth received a saline injection.

The macaques that received the vaccine produced very high levels of antibodies to cocaine. When the monkeys were then injected with cocaine, positron- emission tomography (PET) brain scans showed that very little of the drug bound to its molecular target, the dopamine transporter in the brain [see illustration below]. What is more, the animals showed no behavioural signs of a drug high, such as restlessness or insomnia. Koob and Janda are currently planning a preliminary safety trial of their vaccine in humans.

The pair is also now putting the finishing touches to a heroin vaccine. A vaccine for heroin is trickier to make because heroin is rapidly metabolised into morphine and 6-monoacetylmorphine, both of which act on the brain’s opioid receptors. An effective vaccine therefore has to spur the production of antibodies against heroin’s breakdown products as well as the drug itself. So Koob and Janda made three vaccines in one: they separately attached the virus protein to heroin and its two major metabolites.

In 2013 Koob, Janda and their colleagues tested their compound vaccine in rats addicted to heroin. These animals spent many of their waking hours either searching for or taking heroin, delivered by intravenous infusion whenever the rats pressed a lever. The researchers then removed the heroin and injected half the rats with three doses of vaccine. After 30 days, the vaccinated rats were once again offered heroin. Although the animals tried to get high, they stopped pushing the lever after several minutes, presumably because they were not getting any reward. The rats that had not been vaccinated, in contrast, kept obsessively pressing the lever for heroin.

Whether the vaccine will work in humans is still an open question, however. Human addicts might be more determined than rats to get high, so if a vaccine thwarts that high, instead of giving up, people might wind up taking more of a substance, leading to a massive overdose. In addition, humans have access to other addictive substances. If you have an addict who seriously wants to use drugs and is vaccinated, then the next option could be to use a different drug that the vaccine doesn’t act against….

The Other Half of Addiction

Even if vaccines do not produce such rebound effects, many addiction specialists believe the approach is too narrowly focused on biochemistry to be of much benefit in the real world. A complex interplay between individual psychology and environment is at least half the equation of addiction. Maybe the vaccine would help with the part of addiction that is biological, but what can be done about the other half?

The nicotine vaccine NicVAX, produced by Nabi Biopharmaceuticals, provides a cautionary tale. In large-scale clinical trials conducted from 2009 to 2011, the vaccine (which is nicotine attached to a bacterial antigen) performed no better than placebo in getting people to quit smoking. Koob and other researchers believe, however, that the devil is in the details. They expect other combinations of pathogen proteins and drug molecules—whether nicotine, heroin or cocaine—to fare better.

Koob concedes that vaccines are only part of the solution to the addiction puzzle. “Vaccines aren’t going to cure addiction by any stretch,” he says. “But they will put up an enormous barrier.” If vaccines can help even a fraction of addicts get off drugs, Koob and Janda believe their work will have been worth the effort.

REFERENCES

• Cocaine Vaccine for the Treatment of Cocaine Dependence in Methadone- Maintained Patients: A Randomized, Double-Blind, Placebo-Controlled Efficacy Trial. Bridget A. Martell et al. in Archives of General Psychiatry, 66, No. 10, pages 1116–1123; October 2009.
• A Vaccine Strategy That Induces Protective Immunity against Heroin. Neil Stowe et al. in Journal of Medicinal Chemistry, Vol. 54, No. 14, pages 5195–5204; July 28, 2011.
• Dynamic Vaccine Blocks Relapse to Compulsive Intake of Heroin. Joel E. Schlosburg et al. in Proceedings of the National Academy of Sciences USA, 110, No. 22, pages 9036–9041; May 28, 2013.
• Adenovirus Capsid-Based Anti-Cocaine Vaccine Prevents Cocaine from Binding to the Nonhuman Primate CNS Dopamine Transporter. Anat Maoz et al. in Neuropsychopharmacology, 38, No. 11, pages 2170–2178; October 2013.
• A Shot at Quitting. Carrie Arnold in Scientific American Mind, Vol. 26, No. 1, pages 43-47; January/February 2015

How do hours of Facebook and constant streams of WhatsApp, tweets and text messages affect our cognition and mental health? Scientists are beginning to find out….

Green with FaceBook Envy

Spending a lot of time on Facebook is linked to diminished well-being, according to many studies. Yet questions linger about cause and effect—perhaps people who are already lonely simply spend more time on social media. New studies reveal that Facebook can indeed affect mood and mental state, and whether the effect is positive or negative depends heavily on how a person interacts with his or her contacts. Several of the new findings reveal that when Facebook hurts, the underlying culprit is—you guessed it— envy.

A study published in February 2015 in Computers in Human Behavior surveyed 736 college students and found that when Facebook evoked envy, it increased symptoms of depression. But a March 2015 study from the same journal found that Facebook use can actually decrease depression if users sign on seeking social connection and support and then feel they have received it.

Those studies did not attempt to figure out why some people experienced envy and others did not, but other studies have found that the way a user interacts with Facebook may be crucial. For example, researchers at the University of Michigan and KU Leuven in Belgium tracked 173 students’ habits over time and found that passive use—browsing news feeds, for example—led to reduced well-being by increasing feelings of envy. Active use, such as posting and commenting, had no such effect, according to the two studies, published in April 2015 in the Journal of Experimental Psychology: General.

Another important factor seems to be how close you are to the people with whom you interact. Two related experiments published in November 2015 in Computers in Human Behavior were the first to explore the role of relationship strength in users’ emotional responses to posts on the site. Among a sample of 207 American adults and 194 German college students, the researchers found that people more often felt positive emotions than negative ones when browsing the site, and their emotions were amplified when reading posts from someone they knew well.

Empathy is apparently more pronounced when the relationship is closer, so one is more likely to ‘catch’ the happiness of a close friend than a casual acquaintance. Close friends can inspire envy, too, but the researchers found that this type of envy tended to be benign—the overall reaction to a friend’s good news was usually positive.

The takeaway, the experts say, is that you can control how Facebook makes you feel. If you tend to compare yourself with others or get envious easily, you might consider limiting your time spent on social-networking sites or make a conscious effort to use them in active rather than passive ways. It is not technology such as Facebook that affects our feelings per se but rather how we use it.

Waiting for that Email

There’s nothing like firing off a carefully crafted e-mail and then waiting for what seems like an eternity for a reply. When you finally do get an answer, you might still be frustrated. What do you make of the fact that it is only 10 words long?

We now have some clues about typical email response patterns, thanks to a recent study drawing on 16 billion emails sent by more than two million people. The participants were Yahoo Mail users who allowed their anonymised data to be used in what appears to be the largest-ever analysis of email behaviour. The researchers, based at the University of Southern California and Yahoo Labs, used algorithms to mine data about the times messages were sent and the number of words they contained, among other factors. Here are some of the surprising revelations:

■ The most likely length of a reply is just five words.

■ More than 90 percent of replies are sent within a day.

■ The younger you are, the faster and shorter your reply.

■ Messages sent on weekday mornings got the fastest responses.

■ E-mails with attachments took twice as long to get a reply as those without.

The researchers included only users who wrote to one another at least five times in the months covered by the study period. After mining the data, the researchers found they could use their algorithm to predict when an email conversation was nearing its end. For the first half of a dialogue, correspondents usually developed similar reply times and email lengths, lobbing messages back and forth at a regular clip. Yet that similarity decreased as the conversation trailed off. Many conversations ended with a long lag before one correspondent sent a final brief reply.

Of note to the anxious emailer: the more words in a reply, the longer it tended to take for the writer to send it—but only up to 100 words. Beyond that, the time for a reply actually dropped slightly, except for in the oldest age group. So if you’re expecting a hefty reply to your mission-critical missive, it won’t necessarily take any longer than a 100-word message. That may be some comfort while you wait on the edge of your seat.

How the younger sexes text

Texting has become the most popular form of communication among people under 30. One recent study found that students spend less than six minutes, on average, on schoolwork before being distracted by social media and texting. For a small percentage of teens, texting becomes compulsive—they may try to text less and fail or feel anxiety and frustration if they are kept away from texting. A new study from the American Psychological Association eval- uated how 211 girls and 192 boys communicated via text and found notable gender differences in overall behaviour and compulsive use:

■ Teenage girls use texting for social connection, whereas boys mostly use it to convey information.

■ Boys and girls send about the same number of texts every day, but girls are more likely to become compulsive texters.

■ Teenage girls who compulsively text see a steeper decline in their grades than their compulsive male counterparts. The researchers suggest the social content of girls’ messages may be more likely to distract them from their academic tasks.

■ Compulsive texting also appears to affect girls’ mental health more than boys’, perhaps because girls are more prone to text about negative feelings and to ruminate on those feelings.

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Now that I have your attention, then I may be about to disappoint you.

We are going to be considering whether the size of Woody Allen’s second favourite organ really matters….The Brain.

Does a bigger brain make you necessarily smarter or wiser?

Adjectives such as “highbrow” and “lowbrow” have their origin in the belief, much expounded by 19th-century brain researchers, of a close correspondence between a high forehead—that is, a big brain—and intelligence. Is this true?

Bigger is slightly better

The human brain continues to grow until it reaches its peak size in the third to fourth decade of life. An MRI study of 46 adults of mainly European descent found that the average male had a brain volume of 1,274 cm³ and that the average female brain measured 1,131 cm³. Of course, there is considerable variability in brain volume, ranging from 1,053 to 1,499 cm³ in men and between 975 and 1,398 cm³ in women. As the density of brain matter is just a little bit above that of water plus some salts, the average male brain weighs about 1,325 grams, close to the proverbial three pounds often cited in American texts.

Removing brains after their owners died revealed that Russian novelist Ivan Turgenev’s brain broke the two-kilogram barrier, coming in at 2,021 grams, whereas writer Anatole France’s brain could barely bring half of that weight on the scale at 1,017 grams. (Note that postmortem measures are not directly comparable to data obtained from living brains.) In other words, gross brain size varies considerably across healthy adults.

What about cleverness? We all know from our day-to-day interactions that some people just don’t get it and take a long time to understand a new concept; others have great mental powers. Individuals differ in their ability to understand new ideas, to adapt to new environments, to learn from experience, to think abstractly, to plan and to reason. Psychologists have sought to capture these differences in mental capacities via a number of closely related concepts such as general intelligence (g, or general cognitive ability) and fluid and crystalline intelligence. These differences in people’s ability to figure things out on the spot and to retain and apply insights that they learned in the past to current circumstances are assessed by psychometric intelligence tests. These observations are reliable, in that different tests strongly correlate with one another. They are also stable across decades. That is, measures such as the intelligence quotient (IQ) can be repeatedly and reliably obtained from the same subjects nearly 70 years later.

Differences in general intelligence, assessed in this way, correlate with success in life, with social mobility and job performance, with health and with life span. In a study of one million Swedish men, an increase in IQ by one standard deviation, a measure of variability, was associated with an amazing 32 percent reduction in mortality. Smarter people do better in life. Whereas a high IQ may not predispose people to be happy or to understand the finer points of personal relationships, the highly intelligent are more likely to be found among hedge-fund managers than among supermarket checkout clerks.

What about any numerical relation between brain size and intelligence? Such correlations were difficult to establish in the past when only pathologists had access to skulls and their content. With structural MRI imaging of brain anatomy, such measurements are now routine. In healthy volunteers, total brain volume weakly correlates with intelligence, with a correlation value between 0.3 and 0.4 out of a possible 1.0. In other words, brain size accounts for between 9 and 16 percent of the overall variability in general intelligence. Functional scans, used to look for brain areas linked to particular mental activities, reveal that the parietal, temporal and frontal regions of the cortex, along with the thickness of these regions, correlate with intelligence but, again, only modestly so. Thus, on average, a bigger brain is associated with somewhat higher intelligence. Whether a big brain causes high intelligence or, more likely, whether both are caused by other factors remains unknown.

Recent experiments take into account the particular connections among neurons in certain regions of an individual’s brain, much like a neural fingerprint. They do better at predicting fluid intelligence (the capacity to solve problems in novel situations, to find and match patterns, to reason independently of specific domains of knowledge), explaining about 25 percent of the variance in this measure from one person to the next.

Our ignorance when it comes to how intelligence arises from the brain is accentuated by several further observations. As alluded to earlier, the adult male’s brain is 150 grams heavier than the female’s organ. In the neocortex, the part of the forebrain responsible for perception, memory, language and reasoning, this disparity translates to 23 billion neurons for men versus 19 billion for women. As no difference exists in the average IQ between the two genders, why is there a difference in the basic number of switching elements?

It is also well established that the cranial capacity of Homo neanderthalensis, the proverbial caveman, was 150 to 200 cm3 bigger than that of modern humans. Yet despite their larger brain, Neandertals became extinct between 35,000 and 40,000 years ago, when Homo sapiens shared their European environment. What’s the point of having big brains if your small-brained cousins outcompete you?

Brain size across species

Our lack of understanding of the multiplicity of causes that contribute to intelligence becomes even more apparent when looking outside the genus Homo. Many animals are capable of sophisticated behaviours, including sensory discrimination, learning, decision making, planning and highly adaptive social behaviours.

Consider honeybees. They can recognise faces, communicate the location and quality of food sources to their sisters via the waggle dance, and navigate complex mazes with the help of cues they store in short-term memory. And a scent blown into a hive can trigger a return to the site where the bees previously encountered this odour, a type of associative memory that guides them back and that was made famous by Marcel Proust in his Remembrance of Things Past (À la Recherche du Temps Perdu). The insect does all of this with fewer than one million neurons that weigh around one thousandth of a gram, less than one millionth the size of the human brain. Yet are we really a million times smarter? Certainly not if I look at how well we govern ourselves.

The prevailing rule of thumb holds that the bigger the animal, the bigger its brain. After all, a bigger creature has more skin that has to be innervated and more muscles to control and requires a larger brain to service its body. Thus, it makes sense to control for overall size when studying brain magnitude. By this measure, humans have a relative brain-to-body mass of about 2 percent. What about the big mammals—elephants, dolphins and whales? Their brains far outweigh those of puny humans, up to 10 kilograms for some whales. Given their body mass, ranging from 7,000 kg (for male African elephants) up to 180,000 kg (for the blue whale), their brain-to-body ratio is under a tenth of a percent. Our brains are far bigger relative to our size than those of these creatures. Smugness is not in store, though. We are outclassed by shrews, molelike mammals, whose brain takes up about 10 percent of their entire body mass. Even some birds beat us on this measure. Hmm.

One small consolation is an invention of neuroanatomists called the encephalization quotient (EQ). It is the ratio of the mass of the brain of the species under investigation relative to a standard brain belonging to the same taxonomic group. Thus, if we consider all mammals and compare them against the cat as a reference animal (which therefore has an EQ of 1), people come out on top with an EQ of 7.5. Stated differently, the human brain is 7.5 times bigger than the brain of a typical mammal weighing as much as we do. Apes and monkeys come in at or below five, as do dolphins and other cetaceans. We finally made it to the top, validating our ineradicable belief in humanity’s exceptionalism.

Yet it is not quite clear what all this means in terms of the cellular constituents of brains. Neuroscientists always assumed that humans have more nerve cells where it counts, in the neocortex, than any other species on the planet, no matter the size of their brain.

A 2014 study of 10 long-finned pilot whales from the Faeroe Islands plays havoc with this hypothesis. Caught as part of a local hunt in the cold waters of the North Atlantic, between Scotland and Iceland, these graceful mammals—also known as blackfish—are actually dolphins. The number of nerve cells making up their highly convolved neocortex was estimated in a few sample slices and then extrapolated to the entire structure. The total came to an astonishing 37.2 billion neurons. Astonishing because this implies that the long-finned pilot whale has about twice as many neocortical neurons as humans do!

If what matters for cognitive performance is the number of neocortical neurons, these dolphins should be smarter than all other extant creatures, including us. Whereas the highly playful and social dolphins exhibit a variety of skills, including the ability to recognize themselves in a mirror, they do not possess language or any readily discernible powers of abstraction that stand out from those of other nonhuman animals. So what gives? Is the complexity of the nerve cells themselves substantially less than cells found in people, or is the way these neurons communicate or learn less sophisticated? We don’t know.

People forever ask for the single thing that distinguishes humans from all other animals, on the supposition that this one magical property would explain our evolutionary success—the reason we can build vast cities, put people on the moon, write Anna Karenina and compose Eroica. For a while it was assumed that the secret ingredient in the human brain could be a particular type of neuron, so-called spindle or von Economo neurons, after Baron Constantin von Economo (1876–1931).

But we now know that not only great apes but also whales, dolphins and elephants have these neurons in their frontal cortex. So it’s not brain size, relative brain size or absolute number of neurons that distinguishes us. Perhaps our wiring has become more streamlined, our metabolism more efficient, our synapses more sophisticated.

As Charles Darwin surmised, it is very likely a combination of a great many different factors that jointly, over the gradual course of evolution, made us distinct from other species. We are unique, but so is every other species, each in its own way.

References:

The Evolution of the Brain, the Human Nature of Cortical Circuits, and Intellectual Creativity. Javier DeFelipe in Frontiers in Neuroanatomy, Vol. 5, Article No. 29. Published online May 16, 2011.

Quantitative Relationships in Delphinid Neocortex. Heidi S. Mortensen et al. in Frontiers in Neuroanatomy, Vol. 8, Article No. 132. Published online November 26, 2014.

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At any given time, at least one in five adults reports being on a diet, but the majority don’t keep the weight off. A huge amount of scientific evidence tells us that dieting does not promote lasting weight loss. In fact, many dieters end up gaining back more weight after they quit.

When I say “diet,” I am referring to eating regimens that require cutting potions, severely restricting calories, or eliminating entire food groups: carbs, fats, sweets, whatever. Despite such deprivations, diets remain alluring because they offer a clear and quick prescription dictating what you should and should not eat. These tactics are meant to tame erratic eating behaviours and revise poor food choices. But the truth is that such strategies hardly ever work because they are too extreme and thus almost impossible to maintain over the long term.

In trawling through many papers & articles about losing weight it seems that the best advice from psychologists and researchers are: Do not diet. Do not cut out groups of foods or count calories. Do not try to eat very little or deprive yourself. Such strategies backfire because of psychological effects that every dieter is all too familiar with: intense cravings for foods you have eliminated, bingeing on junk food after falling off the wagon, an intense preoccupation with food. A growing body of research shows why these tendencies undermine most people’s diet efforts and confirms that the way around these pitfalls is moderation. Making small changes to your eating patterns, ones you can build on slowly over time, is truly the best pathway to lasting weight loss. Although you may have heard this message of moderation before, the evidence is finally too overwhelming to ignore.

Effective weight management is particularly important when we consider (most of the studies have been conducted in the States) that two thirds of Americans older than 20 are overweight or obese. With the rise in obesity rates and related health problems, such as diabetes and heart disease—both of which are leading causes of death in the U.S.—it has become even more critical for us all to approach weight loss armed with a keen understanding of what really works and what doesn’t. Let’s start with what doesn’t.

Why Typical Diets Fail

1. The “what the hell effect”

Studies have consistently revealed that dieting usually leads to weight gain, not weight loss. In a 2013 review published online in Frontiers in Psychology, investigators reported that 15 of 20 studies showed that dieting predicted weight gain in adolescents and adults of normal weight.

One problem with diets is that once you give into temptation after restricting yourself, you are more likely to binge. This tendency, which psychologists dub the “what the hell effect,” undermines attempts to lose weight. A 2010 study by psychologists at the University of Toronto demonstrated this effect in people who believed they had broken their diet. In the study, 106 female students—some of whom were dieting and some of whom were not—all received identical slices of pizza. Some of the students saw a person carrying another slice that was either bigger or smaller than the one they got, and others did not see another slice. After they ate the pizza, the participants were asked to taste-test a range of cookies. Women who weren’t dieting and dieters who thought they had eaten a smaller than usual slice or who didn’t see a comparison slice ate a small amount of cookies. But dieters who thought they had violated their diet by eating a bigger slice ate more cookies than everyone else.

The researchers suggest that these women believed they had already blown their diet—so what the hell, might as well pig out on cookies. This study and many others like it confirm that violating or even thinking you have gone off your diet is enough to abandon self-control.

2. Ironic processing

Some diets promise you’ll avoid feelings of deprivation by letting you eat as much as you want of certain food groups while totally eliminating others. The trouble is that when you eliminate your favourite foods—a requirement of most weight-loss regimens—you develop a deeper longing for them. Vow to avoid pasta, and you will soon find yourself dreaming about the plate of spaghetti bolognese or a vegetarian lasagne.

Food preoccupation is an inevitable result of dieting. Psychologists call this phenomenon “ironic processing”—suppressing a thought makes it more salient. It became famous when the late social psychologist Daniel Wegner did a series of experiments—the white bear studies—in which he asked subjects to avoid all thoughts of a white bear. Guess what creature relentlessly prowled through their minds…

Many studies over the years have shown that people who try to eliminate food groups end up craving those foods intensely. One published last year confirms that finding and adds to mounting evidence that not only do people crave the forbidden food, they eat more of it when they get a chance. The study compared eating patterns in 23 normal-weight nondieters who restricted their intake of palatable foods, such as doughnuts and ice cream (again, American studies….), and 23 similar people who merely recorded their snack intake. The researchers found that participants who restricted themselves reported craving and eating more treats, whereas those who simply monitored their snacks did not. This growing line of research suggests that for most, eliminating foods entirely will backfire badly.

In fact, treating yourself to indulgences may help you avoid the pitfalls of craving and overeating forbidden foods. In a 2012 study, 144 obese men and women were put on a strict, low-calorie diet for 16 weeks. About half ate a regular breakfast—300 calories—and the rest consumed a larger breakfast— 600 calories—which included something sweet, such as a doughnut or chocolate (and ate less at dinner to make up for it). In the second half of the study, participants tried to maintain their meal plans on their own for 16 more weeks. The participants kept food diaries and continued to receive counselling from a dietician.

After the initial 16 weeks of close monitoring, the small breakfast group had lost a few more pounds than the large breakfast group (33 versus 30 pounds). But in the self-maintenance 16-week period, the small breakfast group regained 25 pounds, whereas the large breakfast group continued to shrink, dropping 15 additional pounds. Notably the small breakfast group reported increased cravings for sweets, fats and fast foods at the end of the study, whereas the large breakfast group reported reduced cravings in each category. Although eating dessert for breakfast is not necessarily the fastest or healthiest route to weight loss, these findings demonstrate that it is possible to have your cake and lose weight, too.

3. Mental fatigue

Although efforts to change your eating behaviours require attention and record keeping, especially at the beginning, focusing too much energy on what you eat reduces your ability to do other, potentially more important things. Studies that examine the mental energy available to dieters versus nondieters consistently reveal that dieters have more difficulty learning new information, solving problems and exerting self-control.

Overthinking your food choices may also have negative consequences for your mental health. A 2010 study in Appetite looked at the mental toll of eating chocolate among dieters and nondieters. The nondieters were not particularly distracted by this indulgence, but the dieters could no longer think clearly, becoming consumed with thoughts, such as “Why did I eat that?” and “What should I eat later today to make up for eating that?’

Another experiment published in 2010 found that women who restricted their caloric intake and recorded what they ate exhibited elevated cortisol levels, a marker of biological stress. Even women who simply monitored their meals without trying to restrict calories reported feeling more stressed, and they ended up gaining weight. The bottom line is, for most people, that diets not only backfire, they also take a heavy toll on our physical and mental well-being.

What You Should Do

1. Start with your head

If you want to improve your body, you must also improve your mind-set. Decades of research show that individuals who are dissatisfied with their bodies are less successful at losing weight. Studies also show that it is possible for anyone to learn to feel good about his or her body.

In a 2014 study, women with eating disorders, including some who binged or who were over-weight, received compassion-focused therapy— an approach aimed at reducing feelings of shame and improving self-esteem. Over the 12-week treatment, women who exhibited greater improvements in self-compassion and reductions in body shame were also more likely to develop better eating habits.

One simple way to improve your self-esteem, according to many findings, is to write positive affirmations on a regular basis. Happiness research has consistently shown that focusing on what you do like—“I have nice eyes”—and on health rather than appearance-related goals—“I want to run a 5K this year”—can help you develop a healthier mind-set and self-image.

2. Simple, slow and steady

When setting a weight loss goal, it is natural to want to accomplish it immediately. Yesterday please rather than tomorrow! But to maintain a more svelte figure, you need to make gradual, sustainable changes to your diet: for example, drinking less alcohol and juice, substituting diet drinks for (sparkling) water, and eating dessert on four nights a week instead of seven. Making even small changes such as these may sound like a “diet,” which I have just told you to avoid, but it is not, for one important reason: this slow, steady approach allows you to adjust to a new routine at your own pace without the intense effort and denial that typical diet plans require.

Apparently most people trying to lose between 2 and 20 kg will benefit from this slow-to-moderate approach to weight loss, but it is important to note that individuals whose health is at serious risk because of obesity will likely need more drastic measures and should consult a doctor.

A large body of research supports the idea that making simple, gradual changes to your eating patterns is the best way to promote lasting weight loss. Robust evidence for this approach comes from a 2008 study, which demonstrated that overweight and obese adults who made very modest changes to their daily calorie intake and physical activity levels lost four times more weight than those following regimens that involved more extreme calorie restriction. The moderate group lost 10 pounds in one month, and they sustained the weight loss over the next three months.

In support of this approach, a 2015 study published in PLOS ONE found that women who successfully modified their diet and exercise habits over time set small, achievable behaviour change goals, had realistic expectations about their weight loss and were internally motivated to lose weight. The women who relapsed or failed to change their habits tended to have unrealistic expectations, lower motivation and self-confidence, and less satisfaction with their progress.

Some of the most compelling data on effective weight-loss strategies comes from the National Weight Control Registry (NWCR), which surveyed more than 4,000 people who lost at least 14 kg and kept it off for at least a year. The best tactics, according to the seminal 2006 report, included self-monitoring, such as limiting certain foods, keeping track of portion sizes and calories, planning meals and incorporating exercise into the daily routine.

Such advice may appear to conflict with the research I described earlier on the pitfalls of restriction and mental fatigue, but the truth seems to be (based on the research) that, to lose weight, it is important to find the right balance. For instance, before making changes to your diet, you need to understand your current eating patterns, which may require considerable thought and attention. Most overweight individuals, when they are not trying to diet, tend to eat erratically— consuming junk food, snacking a lot and indulging cravings on a whim. Becoming aware of these habits, the good and bad, will allow you to tailor them.

As you begin to make small tweaks to your daily eating, start to plan a few meals you like that you can cycle through on a regular basis, so you don’t have to think too hard about what you’re going to eat every day. According to the NWCR data, people who plan their meals are 1.5 times more likely to maintain their weight loss. The NWCR data also show that limiting the variety of foods you eat can help you sustain your weight. You don’t have to eat the same foods every day, but generally reducing the array of options makes grocery shopping less stressful.

3. Work it out

We all know by now that exercise is essential for all-around health. Yet study after study shows that working out is not terribly effective for weight loss on its own. When combined with better eating habits, however, exercise appears to help people slim down. A 2012 study looked at the effects of diet or exercise, or both or neither, in a group of overweight or obese post-menopausal women. Dieters could consume between 1,200 to 2,000 calories a day, depending on their initial weight, and exercisers ramped up to 45 minutes or more of cardio five days a week. After 12 months, those in the combined diet and exercise group lost the most weight— about 19.5 pounds (8.9 kg)—although the diet-only group was not far behind, losing 15.8 pounds (7.2 kg). Those who only exercised lost 4.4 pounds (2kg) and the control group, who didn’t exercise or eat differently, lost 1.5 pounds (0.7 kg) over the year.

Once your goal weight is achieved, exercise may be crucial for keeping the scale steady. Most people who have slimmed down report that routine physical activity is an important part of their maintenance regimen. Exercise has many physiological benefits; it even appears to moderate the brain’s reaction to pleasurable foods. In a small 2012 study, overweight or obese participants underwent an initial brain scan while looking at images of food. Then they were put on a six-month exercise regimen. At six months, the exercisers showed decreased activity in the insula, which regulates emotions, in response to images of palatable treats. They did not, however, report changes in dietary restraint, food cravings or hunger, suggesting that the neural effects are subtle—perhaps helpful during weight maintenance but not strong enough to induce weight loss.

Incorporating exercise into your life should be a gradual process. You don’t have to run marathons to reap psychological and physical rewards. Going for a lunchtime walk or biking to work is a way to integrate activity into your daily routine. You can also increase your movements in small ways by taking the stairs instead of the lift or washing your car instead of driving through the car wash. Being disciplined is important, but making exercise fun and sustainable is also essential.

4. Don’t do it alone

Receiving social support is key to losing weight. Consulting a doctor or nutritionist is one way to elicit support and provide greater accountability.

Research also demonstrates the role romantic partners play in encouraging weight loss. Research has shown that men are better able to adopt and stick with healthier eating habits when they receive support and encouragement from their spouse. Similarly, friends, co-workers and online weight-loss buddies can keep you on track by offering inspiration, praise and partners in crime. More systematic help has been shown to be useful, too, such as becoming a member of Weight Watchers or other support groups or participating in the community of users of smart-phone apps such as MyFitnessPal and Lose It!

After decades of diet studies, we can no longer ignore the fact that the majority of evidence points toward these small, sustainable steps as the best way to lose weight. That message may not be as sexy or exciting as the latest fad diet, but the science is clear: moderation leads to changes that will last for the rest of your life. Creating good habits takes time, patience and resolve, and you will inevitably encounter setbacks along the way. But the key is to never give up—and in a few short months, you may find yourself on the road to the body and active way of life you’ve always dreamed about.

References:

■ Dietary and Physical Activity Behaviors among Adults Successful at Weight Loss Maintenance. Judy Kruger, Heidi Michels Blanck and Cathleen Gillespie
in International Journal of Behavioral Nutrition and Physical Activity, Vol. 3, Article No. 17. Published online July 19, 2006.

■ Dieting and Restrained Eating as Prospective Predictors of Weight Gain. Michael R. Lowe, Sapna D. Doshi, Shawn N. Katterman and Emily H. Feig in Frontiers in Psychology, Vol. 4, Article No. 577. Published online September 2, 2013.

■ Smart People Don’t Diet: How the Latest Science Can Help You Lose Weight Permanently. Charlotte N. Markey. Da Capo/Lifelong Books, 2014.

From Our Archives

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Textbooks have traditionally taught that when it comes to the immune system, the brain and body are separate entities. When exposed to foreign objects such as bacteria or transplant tissue, the body stirs up a torrent of immune activity: white blood cells devour invading pathogens and burst compromised cells; antibodies tag outsiders for destruction. Except, that is, in the brain, where the blood-brain barrier bars both foreign bodies and immune cells from entry. New research, however, uncovered a previously unknown line of communication between our brain and immune system. The report in July in Nature adds to a fast-growing body of research linking the brain and bodily defenses.

As early as 1921, scientists recognised that the brain is different, immunologically speaking. Tissue grafted into the central nervous system sparks a far less hostile response than tissue grafted to other parts of the body, prompting scientists to consider the brain “immunologically privileged.” Experts have long pointed to the brain’s apparent lack of lymphatic drainage as one reason for this privilege. The lymphatic system is our body’s third set of vessels, along with arteries and veins. Lymph nodes—stationed periodically along the vessel network—serve as storehouses for immune cells. In most parts of the body, foreign invaders trigger the release of these cells through the vessels into the bloodstream.

The new study discovered that the brain is connected to the lymphatic system after all. Working primarily with mice, neuroscientist professor Jonathan Kipnis and his group identified a hitherto undetected network of lymphatic vessels in the meninges—the membranes that surround the brain and spinal cord—that shuttle fluid and immune cells from the cerebrospinal fluid to the deep cervical lymph nodes in the neck. Kipnis and his colleagues had previously shown that a type of white blood cell called a T cell (see picture on right) in the meninges is associated with significant influence on cognition and hence were curious about the role of meningeal immunity on brain function. Using neuroimaging on mouse meninges, the team noticed that T cells were present in vessels separate from arteries and veins.

The newly discovered vessels, which were also identified in human samples, could explain the long-standing conundrum of how the immune system manages to contribute to neurological and psychiatric disease. For example, some cases of multiple sclerosis are thought to result from autoimmune activity in response to an infection in the central nervous system and cerebrospinal fluid. Although Kipnis says that it is too early to speculate he does think that alteration in these vessels may affect disease progression in those neurological disorders with a prominent immune component, such as multiple sclerosis, autism and Alzheimer’s disease.

Some mental illnesses, including depression and schizophrenia, have also been linked with abnormal immune activity and inflammation. Yet scientists have not been able to uncover the underlying mechanism. The new finding suggests a tantalising target for research and, perhaps one day, medicines.

In light of the news, the textbooks might need some revising since it is becoming increasingly clear that the central nervous system is immune-different rather than immune-privileged.

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“Awesome” has become a common descriptor, yet genuine awe is a profound emotion: the intake of breath at a starry night sky, a shiver down your spine during live music or a lump in your throat at the sight of a silent vast crowd holding candles aloft. Can this feeling make us better people? A recent paper in the Journal of Personality and Social Psychology suggests that it does.

Philosophers long ago suggested that awe binds people together. New research carried out at Professor Dacher Keltner’s lab in Berkeley proves that awe can make people less self-involved and more attuned to the needs of the larger group.

In the first of five studies, the researchers ascertained, through a representative national survey, that people who report feeling awe more often are, in fact, more generous. When given raffle tickets and offered the chance to donate some, those who frequently felt awe gave away more tickets.

Then the researchers conducted four other experiments in which they induced awe in some participants and other emotions such as pride or amusement in others. They evoked awe through videos of breathtaking natural scenes and by taking subjects outside to gaze upward at towering eucalyptus trees.

In every case, those who experienced awe behaved in what psychologists call a more “prosocial” way, being more helpful or making more ethical decisions. The participants who had gazed up at the trees, for example, picked up more pens that were “accidentally” dropped by an undercover researcher than other subjects outside who had gazed at a building.

By making us feel like a small part of something grander, awe shifts our attention from our own needs to those of the greater good. Some researchers have speculated that awe might have evolved as the response to a powerful leader. Maintaining social hierarchies and ensuring membership in a group can boost odds of survival.

One of the researchers suggests that people try keeping an “awe diary” for two weeks and every day soak up whatever evokes it—a sunset, a bird’s feathers. Shifting your focus toward something vast is can put your problems in perspective and open you to the greater world. It turns out that awe might also make it healthier too…..

Negative emotions have been linked to poor health outcomes, such as heart disease and even a shorter life span. Research suggests inflammation may be responsible for this link, at least in part. The molecules involved in inflammation are essential for our body’s response to infection and injury, but high levels over the long term have been linked to everything from diabetes to depression.

Few studies have assessed the health effect of positive emotions, so a team led by Jennifer Stellar of the University of Toronto (who also began studying awe in Keltner’s lab at Berkeley) conducted two studies to investigate the link. In the first, 94 students completed a questionnaire to determine how often they had experienced various emotions during the past month. The scientists then took a saliva sample to assess levels of a molecule that promotes inflammation called interleukin-6 (IL-6). They found more positive emotion was associated with lower levels of IL-6.

In the second experiment, 105 students completed online questionnaires designed to assess their tendency to experience several specific positive emotions. They later visited the lab to provide saliva samples. Joy, contentment, pride and awe were all associated with lower levels of IL-6, but awe was the only emotion that significantly predicted levels using a strict statistical test.

These results do not establish whether awe actually causes changes in IL-6 levels. In fact, the authors caution that the relation probably operates in both directions: having a healthier, less stressful life may allow a person to experience more awe. They point out that awe is associated with curiosity and desire to explore, which they contrast with the social withdrawal that often accompanies illness or injury. We know positive emotions are important for well-being, but these initial findings suggest they’re also good for our body.

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The arrival of a child brings big changes in the brains of the new mothers and fathers. Mothers experience a near immediate shift, thanks in part to the hormones involved in giving birth and nursing. Fathers’ brains tend to change in different and more subtle ways.

Is ‘Baby Brain’ a Myth?

As many as four out of every five pregnant women say that they suffer from “pregnancy brain”—deficits in memory and cognitive ability that arise during pregnancy, making women more forgetful and slow-witted. Yet studies on the phenomenon have generally not supported these claims: although some have found evidence of problems on certain types of tasks, others, including a recent paper published by researchers in Utah, have found no signs of cognitive problems at all. Some experts believe that pregnancy brain and its postnatal cousin, “baby brain,” could largely be a product of confirmation bias: pregnant women and new mums expect to experience brain fog and therefore believe they are actually affected. Others argue that the mental symptoms might simply be too difficult to confirm in a laboratory setting.

In the most recent study, researchers at Brigham Young University gave cognitive and neuropsychological tests to 21 women in their third trimester of pregnancy and then tested them again six months after they gave birth. They administered the same tests at similar intervals to 21 women who had never been pregnant. They found no differences between the groups no matter when they were tested, including before and after giving birth. These findings mesh with those from a 2003 study, which found that pregnant women did not score differently from nonpregnant women on tests of verbal memory, divided attention and focused attention.

There is variety in the results, but overall most studies suggest there are few to no memory impairments associated with pregnancy. Researchers think the reason the myth persists may be that women selectively look for evidence that supports the cultural expectation. For example, when a pregnant woman loses her car keys, she might blame pregnancy brain—without recalling the times she lost her car keys before she was pregnant.

There is also another possibility, too. In a 2011 study, a team at the University of British Columbia found that although pregnant women did not display any problems on cognitive tests given in a lab, they were less likely than nonpregnant women to remember to call the lab when asked and to return a questionnaire on time. It is possible that lab-based measures do not reveal differences, because labs are typically quiet environments with minimal distractions, in contrast with everyday life.

Motherhood Can Be a Lonely Place

Entering motherhood is a rite of passage for most women. For many new mums, however, the first months and years can be a lonely place. A new study finds that several types of social support are crucial for staving off negative feelings.

Although only 10 to 15 percent of mothers from Western nations will develop a full-blown case of postpartum depression (PPD), many more will experience some serious symptoms of depression. Feelings of PPD are on a continuum, with PPD at the end. Even if PPD can be diagnosed clinically, there is no standard for measuring where the remaining 85 to 90 percent of mothers land on the scale. Researchers estimate that most first-time mothers are overwhelmed.

Becoming a mother is a major transition. New mothers give up autonomy, sleep and relationships to tend to the relentless needs of a baby. On top of that, they are also expected to be in a constant state of bliss and fulfillment with their new role. There can be a lot of pressure to be the perfect mother, and women can be afraid to say they are not coping.

Making matters worse, research that demonstrates the importance of early childhood experiences in determining future success and happiness puts additional pressure on mums to get it right. Also, for working mothers, who are used to a productive mindset and established social routines, it can be difficult to adapt to the repetitive life of meeting the basic daily needs of a baby. Many women appear to go back to work because of the loneliness.

According to a recent study from Patricia Leahy-Warren at University College Cork in Ireland published in the Journal of Clinical Nursing, mothers with strong social support who have confidence in their ability to parent were 75 percent less likely to be depressed than mothers who had neither advantage. There are four parts to social support: hands-on, emotional, informational and appraisal, meaning affirmation that a mother is doing a good job.

Mums require a network of people to meet these four types of social needs. Generally they lean most on their partner, then their own mother, then sisters. Health professionals, other family and friends can be an important part of a mother’s community. Good social support will also boost a mother’s confidence and ability to parent, Leahy-Warren says, which has a significant positive influence on her mental well-being.

Father’s brain shifts are different

Most investigations of brain changes have focused on mothers, but scientists have recently begun looking more closely at fathers. Neural circuits that support parental behaviours appear more robust in mums a few weeks after the baby is born, whereas in dads the growth can take several months.

A study in Social Neuroscience analysed 16 dads several weeks after their baby’s birth and again a few months later. At each check, the researchers administered a multiple-choice test to check for signs of depression and used MRI to image the brain. Compared with the earlier scans, MRI at three to four months postpartum showed growth in the hypothalamus, amygdala and other regions that regulate emotion, motivation and decision making. Furthermore, dads with more growth in these brain areas were less likely to show depressive.

Although some physiological brain changes are similar in new mums and dads, other changes seem different and could relate to the roles of each parent, as shownn in the brain diagrams below.).

A 2014 behavioral study of expectant fathers showed that midpregnancy ultrasound imaging was a “magic moment” in the dads’ emerging connection with their baby. Yet the emotional bond was different than it is in expectant moms. Instead of thinking about cuddling or feeding the baby, dads-to-be focused on the future: they imagined saving money for higher education or walking down the aisle at their daughter’s wedding.

It is interesting how little dads’ images centred on an infant, instead of what we might assume they would focus on such as putting the baby down for a sleep or changing nappies.

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After wandering round a unfamiliar part of town, can you sense which direction to travel back to get to your car or the station? If so, you can thank your entorhinal cortex, a brain area recently identified as being responsible for our sense of direction. Variation in the signal in this area might even explain why some people are better navigators than others.

The new work adds to a growing understanding of how our brains knows where we are. Groundbreaking discoveries in this field won last year’s Nobel Prize in Physiology or Medicine for John O’Keefe, a neuroscientist at University College in London, who discovered ‘place cells’ in the hippocampus, a brain region most associated with memory. These cells activate when we move into a specific location so that groups of them form a map of the environment.

O’Keefe shared the prize with his former students Edvard Moser and May-Britt Moser, both now at the Kavli Institute for Systems Neuroscience in Norway, who discovered ‘grid cells’ in the entorhinal cortex, a region adjacent to the hippocampus. Grid cells have been called the brain’s GPS system. They are thought to tell us where we are relative to where we started.

A third type – head-direction cells, also found in the entorhinal region – fires when we face a certain direction. Together these specialised neurons appear to enable navigation, but precisely how is still unclear. For instance, in addition to knowing which direction we are facing, we need to know which direction to travel. Little was known about ho or where such a goal-direction signal might me generated in the brain until the new study.

A team of researchers asked 16 volunteers to familiarise themselves with a virtual environment consisting of a square courtyard with a landscape (such as forest or a mountain) on each wall and a unique object in each corner. They then scanned the participants’ brains while showing them views from the environment and asking them to indicate in which direction different objects lay.

The entorhinal region displayed a distinct pattern of activity when volunteers faced each direction – consistent with how head-direction cells should behave. The researchers discovered, however, that the same pattern appeared whether the volunteers were facing a specific direction or just thinking about it. The finding suggests that the same mechanism that signals head direction also simulates goal direction. How, exactly, the brain switches back and forth is unclear, but the researchers think the brain probably signal which direction you are facing until you consciously decide to think about where you want to go, at which point the same cells then run the simulation.

Interestingly, the more consistently the participants’ goal-direction signals were, the better they were able to correctly recall in which direction the target objects lay, potentially offering a brain-based explanation for the differences in navigational ability. Such results should be interpreted carefully, however. There are apparently many ways worse performance can lead to weaker effects; for instance, if a participant’s attention lapses, he or she will not only perform worse but also produce less relevant brain activity.

This work may have clinical relevance. The ability to navigate is often an early casualty of dementias such as Alzheimer’s disease because the entorhinal region is one of the first areas to be affected. One group of neuroscientists is now working with doctors to develop tests to help identify deficits and potentially measure disease progression.

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Sometimes a solution just appears out of nowhere. Intuition!

This is the name we give to the uncanny ability to quickly and effortlessly know the answer, unconsciously, either without or well before knowing why. The conscious explanation comes later, if at all, and involves a much more deliberate process.

Understanding computer code, deciphering a differential equation, diagnosing a tumour from the shadowy patterns on an x-ray image, telling a fake from an authentic painting, knowing when to hold and when to fold in poker. Experts decide in a flash, without thought.

Intuition arises within a well-defined cognitive domain. It may take years of training to develop, and it does not easily transfer from one domain of expertise to another. Chess mastery is useless when playing bridge. Professionals, who may spend a lifetime honing their skills, are much in demand for their proficiency.

Let us consider a series of elegant experiments in functional brain imaging that finger one brain structure as being centrally involved in intuition. Shogi is a Japanese strategy game played on a nine-by-nine board, with two sets of 20 distinct pieces facing each other. It is much more complex than chess, given that captured pieces can be dropped into an empty position anywhere on the board at the discretion of the capturer. This rule multiplies the number of possible moves available at any point in the game and prevents the steady attrition of the two opposing armies that face off in a chess match.

Keiji Tanaka of the RIKEN Brain Science Institute outside Tokyo led a group of cognitive neuroscientists who studied the brains of shogi players, using functional MRI to search for the neural signatures of proficiency. First, subjects inside the scanner looked at drawings of shogi boards taken either from tournament games or from randomly shuffled board positions. They also looked at sketches that had nothing to do with shogi: games of chess and Chinese chess, as well as pictures of faces and houses.

In professional players, pictures of board positions taken from real shogi games activated a piece of cortex, the precuneus in the parietal lobe (located at the top of the brain toward the back), much more strongly than any of the other catgories of pictures. That is, a region of their parietal cortex read out certain perceptual features associated with shogi games and distinguished them from random board positions. Experts see configurations of pieces, lines of control, a weakened defense or an imminent attack—patterns that amateurs do not notice.

In a second experiment, Tanaka and his group presented players with check-matelike shogi puzzles while they lay in the scanner. Subjects had to find the next move that would lead, inexorably, to the capture of the king. They had to do this within one second, pushing them to rely on their intuition because there was no time to analyse the various moves, countermoves, countercountermoves, and so on. When they controlled for confounding cognitive factors, the scientists found nothing activated in the cortex. They did, however, isolate a small region in the front of the caudate nucleus, under the cortex, that reliably and very distinctly turned on in professional shogi players. The caudate was less reliably and less prominently activated when amateur players tried to find the correct move. And when subjects had up to eight seconds to more deliberately search for the best solution, this subcortical region remained silent.

Special-Purpose Hardware

This elegant finding links intuition with the caudate nucleus, which is part of the basal ganglia—a set of interlinked brain areas responsible for learning, executing habits and automatic behaviours. The basal ganglia receive massive input from the cortex, the outer, rindlike surface of the brain. Ultimately these structures project back to the cortex, creating a series of cortical–basal ganglia loops. In one interpretation, the cortex is associated with conscious perception and the deliberate and conscious analysis of any given situation, novel or familiar, whereas the caudate nucleus is the site where highly specialised expertise resides that allows you to come up with an appropriate answer without conscious thought. In computer engineering parlance, a constantly used class of computations (namely those associated with playing a strategy game) is downloaded into special-purpose hardware, the caudate, to lighten the burden of the main processor, the cortex.

So far these experiments relate the task of generating shogi moves to brain activity. Of course, we are not allowed to infer causation from correlation. Just because two things are associated does not imply that one causes the other. As research progresses, the causal structure of intuition and brain activity could be probed by inhibiting or blocking the caudate nucleus to see whether doing so prevents the rapid generation of correct shogi moves. Regrettably there are no reliable technologies to turn bits of brain deep inside the skull on and off in a way conducive to the long-term health of the subject! ;=)

Instead Tanaka and his collaborators wondered whether novices who learn to play shogi wire up their caudate nucleus in a similar manner to that of experts. They recruited naive volunteers and subjected them to an intensive 15-week regime of daily play on a simplified computer version of the game. Motivated by prize money, the subjects improved over the approximately 100 days of training, during which they accumulated total practice time ranging from 37 to 107 hours.

Asking subjects in these experiments to quickly come up with the best next move led to increased cortical activity, but that activity did not change over the training period, nor did it correlate with the fraction of correct responses. In contrast, changes in blood flow in the front of the caudate nucleus evolved over the course of training in parallel with better performance. Furthermore, the strength of the caudate signal at the end of the training correlated with how much subjects improved over time. The more the subject learned, the larger the caudate signal.

It appears that the site of fast, automatic, unconscious cognitive operations—from where a solution materialises all of a sudden—lies in the basal ganglia, linked to, but apart from, the cortex. These studies begin to provide a telling hint of what happens when the brain brings the output of unconscious processing into awareness. My intuition tells me that the last word on this subject has not been written by a long way!