Chapter 14. Attention and Consciousness
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By JOSEPH LEDOUX IN this age of terror, we struggle to figure out how to protect ourselves — especially, of late, from active shooters. One suggestion, promoted by the Federal Bureau of Investigation and Department of Homeland Security, and now widely disseminated, is “run, hide, fight.” The idea is: Run if you can; hide if you can’t run; and fight if all else fails. This three-step program appeals to common sense, but whether it makes scientific sense is another question. Underlying the idea of “run, hide, fight” is the presumption that volitional choices are readily available in situations of danger. But the fact is, when you are in danger, whether it is a bicyclist speeding at you or a shooter locked and loaded, you may well find yourself frozen, unable to act and think clearly. Freezing is not a choice. It is a built-in impulse controlled by ancient circuits in the brain involving the amygdala and its neural partners, and is automatically set into motion by external threats. By contrast, the kinds of intentional actions implied by “run, hide, fight” require newer circuits in the neocortex. Contemporary science has refined the old “fight or flight” concept — the idea that those are the two hard-wired options when in mortal danger — to the updated “freeze, flee, fight.” While “freeze, flee, fight” is superficially similar to “run, hide, fight,” the two expressions make fundamentally different assumptions about how and why we do what we do, when in danger. Why do we freeze? It’s part of a predatory defense system that is wired to keep the organism alive. Not only do we do it, but so do other mammals and other vertebrates. Even invertebrates — like flies — freeze. If you are freezing, you are less likely to be detected if the predator is far away, and if the predator is close by, you can postpone the attack (movement by the prey is a trigger for attack). © 2015 The New York Times Company
Scientists showed that they could alter brain activity of rats and either wake them up or put them in an unconscious state by changing the firing rates of neurons in the central thalamus, a region known to regulate arousal. The study, published in eLIFE, was partially funded by the National Institutes of Health. “Our results suggest the central thalamus works like a radio dial that tunes the brain to different states of activity and arousal,” said Jin Hyung Lee, Ph.D., assistant professor of neurology, neurosurgery and bioengineering at Stanford University, and a senior author of the study. Located deep inside the brain the thalamus acts as a relay station sending neural signals from the body to the cortex. Damage to neurons in the central part of the thalamus may lead to problems with sleep, attention, and memory. Previous studies suggested that stimulation of thalamic neurons may awaken patients who have suffered a traumatic brain injury from minimally conscious states. Dr. Lee’s team flashed laser pulses onto light sensitive central thalamic neurons of sleeping rats, which caused the cells to fire. High frequency stimulation of 40 or 100 pulses per second woke the rats. In contrast, low frequency stimulation of 10 pulses per second sent the rats into a state reminiscent of absence seizures that caused them to stiffen and stare before returning to sleep. “This study takes a big step towards understanding the brain circuitry that controls sleep and arousal,” Yejun (Janet) He, Ph.D., program director at NIH’s National Institute of Neurological Disorders and Stroke (NINDS).
Link ID: 21711 - Posted: 12.19.2015
By Geoffrey S. Holtzman In November 1834, a 9-year-old boy named Major Mitchell was tried in Maine on one charge of maiming and one charge of felonious assault with intent to maim. He had lured an 8-year-old classmate into a field, beaten him with sticks, attempted to drown him in a stream, and castrated him with a piece of tin. Yet what makes this case so remarkable is neither the age of the defendant nor the violence of his crime, but the nature of his trial. Mitchell’s case marks the first time in U.S. history that a defendant’s attorney sought leniency from a jury on account of there being something wrong with the defendant’s brain. More recently, there has been an explosion in the number of criminals who have sought leniency on similar grounds. While the evidence presented by Mitchell’s defense was long ago debunked as pseudoscience (and was rightly dismissed by the judge), the case for exculpating Major Mitchell may actually be stronger today than it was 181 years ago. In a curious historical coincidence, recent advances in neuroscience suggest that there really might have been something wrong with Major Mitchell’s brain and that neurological deficits really could have contributed to his violent behavior. The case provides a unique window through which to view the relationship between 19th-century phrenology—the pseudoscientific study of the skull as an index of mental faculties—and 21st-century neuroscience. As you might expect, there is a world of difference between the two, but maintaining that difference depends crucially on the responsible use of neuroscience. Major Mitchell’s story cautions against overlooking neuroscience’s limitations, as well as its ability to be exploited for suspect purposes. © 2015 The Slate Group LLC.
The road map of conscious awareness has been deciphered. Now that we know which brain pathways control whether someone is awake or unconscious, we may be able to rouse people from a vegetative or minimally conscious state. In 2007, researchers used deep brain stimulation to wake a man from a minimally conscious state. It was quite remarkable, says Jin Lee at Stanford University in California. The 38-year-old had suffered a severe brain injury in a street mugging six years earlier. Before his treatment he was unable to communicate and had no voluntary control over his limbs. When doctors stimulated his thalamus – a central hub that sends signals all around the brain – his speech and movement gradually returned. However, attempts to treat other people in a similar way have failed. The problem lies with the crudeness of the technique. “Deep brain stimulation is done without much knowledge of how it actually alters the circuits in the brain,” says Lin. The technique involves attaching electrodes to the brain and using them to stimulate the tissue beneath. Unfortunately, the electrodes can also stimulate unintended areas, which means it is hard to work out exactly what is happening in people’s brains. “There are a lot of fibres and different cells in the thalamus and working out what was going on in the brain was very difficult,” says Lin. “So we wanted to figure it out.” © Copyright Reed Business Information Ltd.
By Ariana Eunjung Cha Attention-deficit/hyperactivity disorder is often thought of a boy thing. In explaining the jump in cases in recent years, numerous researchers, educators and parents have theorized that perhaps boys are hardwired to be more impulsive, wiggly and less able to stay on task in the early years than their female counterparts. That may be a myth. A study published in The Journal of Clinical Psychiatry on Tuesday shows a surprising 55 percent increase in prevalence of diagnoses among girls — from 4.7 percent to 7.3 percent from 2003 to 2011. The rise in cases in girls mirrors a similar but less-sharp rise in cases in boys from a prevalence of 11.8 to 16.5 percent. During the same period, the researchers found an increase in cases across all races and ethnicities but especially in Hispanic children. In all children, the prevalence increased from 8.4 percent to 12 percent. The analysis, conducted by George Washington University biostatistician Sean D. Cleary and his co-author Kevin P. Collins of Mathematica Policy Research, was based on data from the National Survey of Children's Health in which parents were asked whether they had been told by a doctor or other health care provider that their child has ADHD.
By John Horgan How does matter make mind? More specifically, how does a physical object generate subjective experiences like those you are immersed in as you read this sentence? How does stuff become conscious? This is called the mind-body problem, or, by philosopher David Chalmers, the “hard problem.” I expressed doubt that the hard problem can be solved--a position called mysterianism--in The End of Science. I argue in a new edition that my pessimism has been justified by the recent popularity of panpsychism. This ancient doctrine holds that consciousness is a property not just of brains but of all matter, like my table and coffee mug. Panpsychism strikes me as self-evidently foolish, but non-foolish people—notably Chalmers and neuroscientist Christof Koch—are taking it seriously. How can that be? What’s compelling their interest? Have I dismissed panpsychism too hastily? These questions lured me to a two-day workshop on integrated information theory at New York University last month. Conceived by neuroscientist Guilio Tononi (who trained under the late, great Gerald Edelman), IIT is an extremely ambitious theory of consciousness. It applies to all forms of matter, not just brains, and it implies that panpsychism might be true. Koch and others are taking panpsychism seriously because they take IIT seriously. © 2015 Scientific American
Link ID: 21673 - Posted: 12.03.2015
Aimee Cunningham For a child with attention deficit hyperactivity disorder, meeting the daily expectations of home and school life can be a struggle that extends to bedtime. The stimulant medications commonly used to treat ADHD can cause difficulty falling and staying asleep, a study finds. And that can make the next day that much harder. As parents are well aware, sleep affects a child's emotional and physical well-being, and it is no different for those with ADHD. "Poor sleep makes ADHD symptoms worse," says Katherine M. Kidwell, a doctoral student in clinical psychology at the University of Nebraska, Lincoln, who led the study. "When children with ADHD don't sleep well, they have problems paying attention the next day, and they are more impulsive and emotionally reactive." Stimulant medications boost alertness, and some studies have found a detrimental effect on children's sleep. However, other studies have concluded that the stimulants' ameliorating effects improve sleep. The drugs include amphetamines such as Adderall and methylphenidate such as Ritalin. To reconcile the mixed results on stimulants and children's sleep, Kidwell and her colleagues undertook a meta-analysis, a type of study that summarizes the results of existing research. The team found nine studies that met their criteria. These studies compared children who were taking stimulant medication with those who weren't. The studies also randomly assigned children to the experimental group or the control group and used objective measures of sleep quality and quantity, such as assessing sleep in a lab setting or with a wristwatch-like monitor at home rather than a parent's report. © 2015 npr
By Virginia Morell Was that fish on your plate once a sentient being? Scientists have long believed that the animals aren’t capable of the same type of conscious thought we are because they fail the “emotional fever” test. When researchers expose birds, mammals (including humans), and at least one species of lizard to new environments, they experience a slight rise in body temperature of 1°C to 2°C that lasts a while; it’s a true fever, as if they were responding to an infection. The fever is linked to the emotions because it’s triggered by an outside stimulus, yet produces behavioral and physiological changes that can be observed. Some scientists argue that these only occur in animals with sophisticated brains that sense and are conscious of what’s happening to them. Previous tests suggested that toads and fish don’t respond this way. Now, a new experiment that gave the fish more choices shows the opposite. Researchers took 72 zebrafish and either did nothing with them or placed them alone in a small net hanging inside a chamber in their tank with water of about 27°C; zebrafish prefer water of about 28°C. After 15 minutes in the net, the team released the confined fish. They could then freely swim among the tank’s five other chambers, each heated to a different temperature along a gradient from 17.92°C to 35°C. (The previous study used a similar setup but gave goldfish a choice between only two chambers, both at higher temperatures.) The stressed fish spent more time—between 4 and 8 hours—in the warmer waters than did the control fish, and raised their body temperatures about 2°C to 4°C, showing an emotional fever, the scientists report online today in the Proceedings of the Royal Society B. Thus, their study upends a key argument against consciousness in fish, they say. © 2015 American Association for the Advancement of Science.
Jon Hamilton A look at the brain's wiring can often reveal whether a person has trouble staying focused, and even whether they have attention deficit hyperactivity disorder, known as ADHD. A team led by researchers at Yale University reports that they were able to identify many children and adolescents with ADHD by studying data on the strength of certain connections in their brains. "There's an intrinsic signature," says Monica Rosenberg, a graduate student and lead author of the study in Nature Neuroscience. But the approach isn't ready for use as a diagnostic tool yet, she says. The finding adds to the evidence that people with ADHD have a true brain disorder, not just a behavioral problem, says Mark Mahone, director of neuropsychology at the Kennedy Krieger institute in Baltimore. "There are measurable ways that their brains are different," he says. The latest finding came from an effort to learn more about brain connections associated with attention. Initially, the Yale team used functional MRI, a form of magnetic resonance imaging, to monitor the brains of 25 typical people while they did something really boring. Their task was to watch a screen that showed black-and-white images of cities or mountains and press a button only when they saw a city. © 2015 npr
Alva Noë For some time now, I've been skeptical about the neuroscience of consciousness. Not so much because I doubt that consciousness is affected by neural states and processes, but because of the persistent tendency on the part of some neuroscientists to think of consciousness itself as a neural phenomenon. Nothing epitomizes this tendency better than Francis Crick's famous claim — he called it his "astonishing hypothesis" — that you are your brain. At an interdisciplinary conference at Brown not so long ago, I heard a prominent neuroscientist blandly assert, as if voicing well-established scientific fact, that thoughts, feelings and beliefs are specific constellations of matter that are located (as it happens) inside the head. My own view — I laid this out in a book I wrote a few years back called Out of Our Heads — is that the brain is only part of the story, and that we can only begin to understand how the brain makes us consciousness by realizing that brain functions only in the setting of our bodies and our broader environmental (including our social and cultural) situation. The skull is not a magical membrane, my late collaborator, friend and teacher Susan Hurley used to say. And there is no reason to think the processes supporting consciousness are confined to what happens only on one side (the inside) of that boundary. There is a nice interview on the Oxford University Press website with Anil Seth, the editor of a new Oxford journal Neuroscience of Consciousness. It's an informative discussion and makes the valuable point that the study of consciousness is interdisciplinary. © 2015 npr
Link ID: 21631 - Posted: 11.14.2015
By Katherine Ellison Last year, Sinan Sonmezler of Istanbul refused to keep going to school. His eighth-grade classmates called him “weird” and “stupid,” and his teachers rebuked him for his tendency to stare out the window during class. The school director told his parents he was “lazy.” Sinan has attention-deficit hyperactivity disorder, a condition still little understood in many parts of the world. “He no longer believes he can achieve anything, and has quit trying,” said Sinan’s father, Umit Sonmezler, a mechanical engineer. While global diagnoses of A.D.H.D. are on the rise, public understanding of the disorder has not kept pace. Debates about the validity of the diagnosis and the drugs used to treat it — the same that have long polarized Americans — are now playing out from Northern and Eastern Europe to the Middle East and South America. Data from various nations tell a story of rapid change. In Germany, A.D.H.D. diagnosis rates rose 381 percent from 1989 to 2001. In the United Kingdom, prescriptions for A.D.H.D. medications rose by more than 50 percent in five years to 657,000 in 2012, up from 420,000 in 2007. Consumption of A.D.H.D. medications doubled in Israel from 2005 to 2012. The surge in use of the medications has prompted skepticism that pharmaceutical firms, chasing profits in an $11 billion international market for A.D.H.D. drugs, are driving the global increase in diagnoses. In 2007, countries outside the United States accounted for only 17 percent of the world’s use of Ritalin. By 2012, that number had grown to 34 percent. © 2015 The New York Times Company
Link ID: 21618 - Posted: 11.10.2015
Doubts are emerging about one of our leading models of consciousness. It seems that brain signals thought to reflect consciousness are also generated during unconscious activity. A decade of studies have lent credence to the global neuronal workspace theory of consciousness, which states that when something is perceived unconsciously, or subliminally, that information is processed locally in the brain. In contrast, conscious perception occurs when the information is broadcast to a “global workspace”, or assemblies of neurons distributed across various brain regions, leading to activity over the entire network. Proponents of this idea, Stanislas Dehaene at France’s national institute for health in Gif-sur-Yvette, and his colleagues, discovered that when volunteers view stimuli that either enter conscious awareness or don’t, their brains show identical EEG activity for the first 270 milliseconds. Then, if perception of the stimuli is subliminal, the brain activity peters out. However, when volunteers become conscious of the stimuli, there is a sudden burst of widespread brain activity 300 ms after the stimulus. This activity is characterised by an EEG signal called P3b, and has been called a neural correlate of consciousness. Brian Silverstein and Michael Snodgrass at the University of Michigan in Ann Arbor, and colleagues wondered if P3b could be detected during unconscious processing of stimuli. © Copyright Reed Business Information Ltd.
Link ID: 21603 - Posted: 11.05.2015
Scientists have come up with a questionnaire they say should help diagnose a condition called face blindness. Prosopagnosia, as doctors call it, affects around two in every 100 people in the UK and is the inability to recognise people by their faces alone. In its most extreme form, people cannot even recognise their family or friends. Milder forms, while still distressing, can be tricky to diagnose, which is why tests are needed. People with prosopagnosia often use non-facial cues to recognise others, such as their hairstyle, clothes, voice, or distinctive features. Some may be unaware they have the condition, instead believing they have a "bad memory for faces". But prosopagnosia is entirely unrelated to intelligence or broader memory ability. One [anonymous] person with prosopagnosia explains: "My biggest problem is seeing the difference between ordinary-looking people, especially faces with few specific traits. "I work at a hospital with an awful lot of employees and I often introduce myself to colleagues with whom I have worked several times before. I also often have problems recognising my next-door neighbour, even though we have been neighbours for eight years now. She often changes clothes, hairstyle and hair colour. When I strive to recognise people, I try to use technical clues like clothing, hairstyle, scars, glasses, their dialect and so on." Doctors can use computer-based tests to see if people can spot famous faces and memorise and recognise a set of unfamiliar faces. And now Drs Richard Cook, Punit Shah and City University London and Kings College London have come up with a 20-item questionnaire to help measure the severity of someone's face blindness. © 2015 BBC
Link ID: 21598 - Posted: 11.04.2015
By Christian Jarrett Neuroscientists, for obvious reasons, are really interested in finding out what’s different about the brains of people with unpleasant personalities, such as narcissists, or unsavory habits, like porn addiction. Their hope is that by studying these people’s brains we might learn more about the causes of bad character, and ways to helpfully intervene. Now to the list of character flaws that've received the brain-scanner treatment we can apparently add sexism — a new Japanese study published in Scientific Reports claims to have found its neurological imprint. The researchers wanted to know whether there is something different about certain individuals’ brains that potentially predisposes them to sexist beliefs and attitudes (of course, as with so much neuroscience research like this, it’s very hard to disentangle whether any observed brain differences are the cause or consequence of the trait or behavior that’s being studied, a point I’ll come back to). More specifically, they were looking to see if people who publicly endorse gender inequality have brains that are anatomically different from people who believe in gender equality. In short, it seems the answer is yes. Neuroscientist Hikaru Takeuchi at Tohoku University and his colleagues have identified two brain areas where people who hold sexist attitudes have different levels of gray-matter density (basically, a measure of how many brain cells are packed into a given area), as compared with people who profess a belief in gender equality (their study doesn’t speak to any subconsciously held sexist beliefs). What’s more, these neural differences were correlated with psychological characteristics that could help explain some people’s sexist beliefs. © 2015, New York Media LLC.
By ALEX HUTCHINSON WHEN marketing researchers at the University of Pennsylvania’s Wharton School rigged shopping carts at a major East Coast supermarket with motion-tracking radio-frequency tags, they unwittingly stumbled on a metaphor for our path through the aisles of life. Route data from more than 1,000 shoppers, matched to their purchases at checkout, revealed a clear pattern: Drop a bunch of kale into your cart and you’re more likely to head next to the ice cream or beer section. The more “virtuous” products you have in your basket, the stronger your temptation to succumb to vice. Such hedonic balancing acts are neither unpredictable — who, after all, hasn’t rewarded themselves with a piece of cake or an extra beer after a killer workout? — nor inherently bad. But an emerging body of research into what psychologists call the “licensing effect” suggests that this tit-for-tat tendency is deeply wired in us, operating even when we’re not aware of it. And in a world where we’re bombarded by pitches for an endless array of health-boosting products of dubious efficacy, that can be a problem. The key insight underlying the licensing effect, which was first described in 2006 by Uzma Khan, then a professor of marketing at Carnegie Mellon University, and Ravi Dhar of the Yale School of Management, is that our choices are contingent: Since we each have a fairly stable self-concept of how good/bad, healthy/unhealthy or selfish/altruistic we are, when one decision swings too far from this self-concept, we automatically take action to balance it out. © 2015 The New York Times Company
Dyscalculia is like dyslexia — but for those who have trouble with math instead of reading. But not enough people know about it, according to a neuroscientist. "There is a lack of awareness among teachers and educators," said Daniel Ansari, professor and Canada Research Chair in Developmental Cognitive Neuroscience at the University of Western Ontario. Individuals with dyscalculia have trouble with simple calculations. "If I ask you what is 1 + 3, you don't need to calculate. Four will pop in to your head, it is stored in your long-term memory," he said. But those with dyscalculia will have to use their hands to count. Scientists have known about dyscalculia since the 1940's but little research has been done on it, even though it is probably just as common as dyslexia, says Ansari. Currently, there is no existing universal form of testing for dyscalculia. But Ansari has come up with screening tests for children in kindergarten. He says it's important to diagnose dyscalculia early on, so individuals can learn to adapt and improve their skills before it's too late. "We don't just need math to be good in school but to function in society," said Ansari. He says research has shown poor math skills can lead to an increased chance of unemployment, imprisonment or mortgage default. ©2015 CBC/Radio-Canada.
Link ID: 21564 - Posted: 10.26.2015
In a study of mice, scientists discovered that a brain region called the thalamus may be critical for filtering out distractions. The study, published in Nature and partially funded by the National Institutes of Health, paves the way to understanding how defects in the thalamus might underlie symptoms seen in patients with autism, attention deficit hyperactivity disorder (ADHD), and schizophrenia. “We are constantly bombarded by information from our surroundings,” said James Gnadt, Ph.D., program director at the NIH’s National Institute of Neurological Disorders and Stroke (NINDS). “This study shows how the circuits of the brain might decide which sensations to pay attention to.” Thirty years ago Dr. Francis Crick proposed that the thalamus “shines a light” on regions of the cortex, which readies them for the task at hand, leaving the rest of the brain’s circuits to idle in darkness. “We typically use a very small percentage of incoming sensory stimuli to guide our behavior, but in many neurological disorders the brain is overloaded,” said Michael Halassa, M.D., Ph.D., the study’s senior author and an assistant professor at New York University’s Langone Medical Center. “It gets a lot of sensory input that is not well-controlled because this filtering function might be broken.” Neuroscientists have long believed that an area at the very front of the brain called the prefrontal cortex (PFC) selects what information to focus on, but how this happens remains unknown. One common theory is that neurons in the PFC do this by sending signals to cells in the sensory cortices located on the outer part of the brain. However, Dr. Halassa’s team discovered that PFC neurons may instead tune the sensitivity of a mouse brain to sights and sounds by sending signals to inhibitory thalamic reticular nucleus (TRN) cells located deep inside the brain.
Link ID: 21545 - Posted: 10.22.2015
Susan Gaidos CHICAGO — Teens like high-tech gadgets so much that they often use them all at once. While doing homework or playing video games, teens may listen to music or watch TV, all the while texting their friends. Some of these multitaskers think they are boosting their ability to attend to multiple activities, but in fact are more likely impairing their ability to focus, psychologist Mona Moisala of the University of Helsinki, reported October 18 at the annual meeting of the Society for Neuroscience. Moisala and colleagues tested 149 adolescents and young adults, ages 13 to 24, who regularly juggle multiple forms of media or play video games daily. Each participant had to focus attention on sentences (some logical, some illogical) under three conditions: without any distractions, while listening to distracting sounds, and while both listening to a sentence and reading another sentence. Using functional MRI to track brain activity, the researchers found that daily gaming had no effect on participants’ ability to focus. Those who juggle multiple forms of electronic media, however, had more trouble paying attention. Multitaskers performed lower overall, even when they weren’t being distracted. Brain images showed that the multitaskers also showed a higher level of activity in the right prefrontal cortex, an area of the brain implicated in problem solving and in processing complex thoughts and emotions. “Participants with the highest reported frequency of multimedia use showed the highest levels of brain activation in this area,” Moisala said. “In addition, these adolescents did worse on the task.” © Society for Science & the Public 2000 - 2015
Link ID: 21529 - Posted: 10.20.2015
by Bethany Brookshire It’s happened to all of us at one time or another: You’re walking through a crowd, and suddenly a face seems incredibly familiar — so much so that you do a double-take. Who is that? How do you know them? You have no idea, but something about their face nags at you. You know you’ve seen it before. The reason you know that face is in part because of your perirhinal cortex. This is an area of the brain that helps us to determine familiarity, or whether we have seen an object before. A new study of brain cells in this area finds that firing these neurons at one frequency makes the brain treat novel images as old hat. But firing these same neurons at another frequency can make the old new again. “Novelty and familiarity are both really important,” says study coauthor Rebecca Burwell, a neuroscientist at Brown University in Providence, R.I. “They are important for learning and memory and decision making.” Finding a cache of food and knowing it is new could be useful for an animal’s future. So is recognizing a familiar place where the pickings were good in the past. But knowing that something is familiar is not quite the same thing as knowing what that thing is. “You’re in a crowd and you see a familiar face, and there’s a feeling,” Burwell explains. “You can’t identify them, you don’t know where you met them, but there’s a sense of familiarity.” It’s different from recalling where you met the person, or even who the person is. This is a sense at the base of memory. And while scientists knew the perirhinal cortex was involved in this sense of familiarity, how that feeling of new or old was coded in the brain wasn’t fully understood. © Society for Science & the Public 2000 - 2015
Link ID: 21511 - Posted: 10.14.2015
By ERICA GOODE Women who suffer from anorexia are often thought of as having an extraordinary degree of self-control, even if that discipline is used self-destructively. But a new study suggests that the extreme dieting characteristic of anorexia may instead be well-entrenched habit — behavior governed by brain processes that, once set in motion, are inflexible and slow to change. The study’s findings may help explain why the eating disorder, which has the highest mortality rate of any mental illness, is so stubbornly difficult to treat. But they also add to increasing evidence that the brain circuits involved in habitual behavior play a role in disorders where people persist in making self-destructive choices no matter the consequences, like cocaine addiction or compulsive gambling. In the case of anorexia, therapists often feel helpless to interrupt the relentless dieting that anorexic patients pursue. Even when patients say they want to recover, they often continue to eat only low-fat, low-calorie foods. Neither psychiatric medications nor talk therapies that are used successfully for other eating disorders are much help in most cases. And research suggests that 50 percent or more of hospitalized anorexic patients who are discharged at a normal weight will relapse within a year. “The thing about people with anorexia nervosa is that they can’t stop,” said Dr. Joanna E. Steinglass, an associate professor in clinical psychiatry at the New York State Psychiatric Institute at Columbia University Medical Center and a co-author of the new study, which appears in the journal Nature Neuroscience. “They come into treatment saying they want to get better, and they can’t do it,” Dr. Steinglass added. Karin Foerde, a research scientist at the psychiatric institute and Columbia, was the lead author on the study. © 2015 The New York Times Company