Neuroscience

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Posts tagged motivation

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Scientists Discover Area of Brain Responsible for Exercise Motivation Scientists at Seattle Children’s Research Institute have discovered an area of the brain that could control a person’s motivation to exercise and participate in other rewarding activities – potentially leading to improved treatments for depression. Dr. Eric Turner, a principal investigator in Seattle Children’s Research Institute’s Center for Integrative Brain Research, together with lead author Dr. Yun-Wei (Toni) Hsu, have discovered that a tiny region of the brain – the dorsal medial habenula – controls the desire to exercise in mice. The structure of the habenula is similar in humans and rodents and these basic functions in mood regulation and motivation are likely to be the same across species.   Exercise is one of the most effective non-pharmacological therapies for depression. Determining that such a specific area of the brain may be responsible for motivation to exercise could help researchers develop more targeted, effective treatments for depression.  “Changes in physical activity and the inability to enjoy rewarding or pleasurable experiences are two hallmarks of major depression,” Turner said. “But the brain pathways responsible for exercise motivation have not been well understood. Now, we can seek ways to manipulate activity within this specific area of the brain without impacting the rest of the brain’s activity.”  Dr. Turner’s study, titled “Role of the Dorsal Medial Habenula in the Regulation of Voluntary Activity, Motor Function, Hedonic State, and Primary Reinforcement,” was published today by the Journal of Neuroscience and funded by the National Institute of Mental Health and National Institute on Drug Abuse. The study used mouse models that were genetically engineered to block signals from the dorsal medial habenula. In the first part of the study, Dr. Turner’s team collaborated with Dr. Horacio de la Iglesia, a professor in University of Washington’s Department of Biology, to show that compared to typical mice, who love to run in their exercise wheels, the genetically engineered mice were lethargic and ran far less. Turner’s genetically engineered mice also lost their preference for sweetened drinking water.  “Without a functioning dorsal medial habenula, the mice became couch potatoes,” Turner said. “They were physically capable of running but appeared unmotivated to do it.”  In a second group of mice, Dr. Turner’s team activated the dorsal medial habenula using optogenetics – a precise laser technology developed in collaboration with the Allen Institute for Brain Science. The mice could “choose” to activate this area of the brain by turning one of two response wheels with their paws. The mice strongly preferred turning the wheel that stimulated the dorsal medial habenula, demonstrating that this area of the brain is tied to rewarding behavior.   Past studies have attributed many different functions to the habenula, but technology was not advanced enough to determine roles of the various subsections of this area of the brain, including the dorsal medial habenula.  “Traditional methods of stimulation could not isolate this part of the brain,” Turner said. “But cutting-edge technology at Seattle Children’s Research Institute makes discoveries like this possible.”  As a professor in the University of Washington Department of Psychiatry and Behavioral Sciences, Dr. Turner treats depression and hopes this research will make a difference in the lives of future patients.  “Working in mental health can be frustrating,” Turner said. “We have not made a lot of progress in developing new treatments. I hope the more we can learn about how the brain functions the more we can help people with all kinds of mental illness.”

Scientists Discover Area of Brain Responsible for Exercise Motivation

Scientists at Seattle Children’s Research Institute have discovered an area of the brain that could control a person’s motivation to exercise and participate in other rewarding activities – potentially leading to improved treatments for depression.

Dr. Eric Turner, a principal investigator in Seattle Children’s Research Institute’s Center for Integrative Brain Research, together with lead author Dr. Yun-Wei (Toni) Hsu, have discovered that a tiny region of the brain – the dorsal medial habenula – controls the desire to exercise in mice. The structure of the habenula is similar in humans and rodents and these basic functions in mood regulation and motivation are likely to be the same across species.  

Exercise is one of the most effective non-pharmacological therapies for depression. Determining that such a specific area of the brain may be responsible for motivation to exercise could help researchers develop more targeted, effective treatments for depression. 

“Changes in physical activity and the inability to enjoy rewarding or pleasurable experiences are two hallmarks of major depression,” Turner said. “But the brain pathways responsible for exercise motivation have not been well understood. Now, we can seek ways to manipulate activity within this specific area of the brain without impacting the rest of the brain’s activity.” 

Dr. Turner’s study, titled “Role of the Dorsal Medial Habenula in the Regulation of Voluntary Activity, Motor Function, Hedonic State, and Primary Reinforcement,” was published today by the Journal of Neuroscience and funded by the National Institute of Mental Health and National Institute on Drug Abuse. The study used mouse models that were genetically engineered to block signals from the dorsal medial habenula. In the first part of the study, Dr. Turner’s team collaborated with Dr. Horacio de la Iglesia, a professor in University of Washington’s Department of Biology, to show that compared to typical mice, who love to run in their exercise wheels, the genetically engineered mice were lethargic and ran far less. Turner’s genetically engineered mice also lost their preference for sweetened drinking water. 

“Without a functioning dorsal medial habenula, the mice became couch potatoes,” Turner said. “They were physically capable of running but appeared unmotivated to do it.” 

In a second group of mice, Dr. Turner’s team activated the dorsal medial habenula using optogenetics – a precise laser technology developed in collaboration with the Allen Institute for Brain Science. The mice could “choose” to activate this area of the brain by turning one of two response wheels with their paws. The mice strongly preferred turning the wheel that stimulated the dorsal medial habenula, demonstrating that this area of the brain is tied to rewarding behavior.  

Past studies have attributed many different functions to the habenula, but technology was not advanced enough to determine roles of the various subsections of this area of the brain, including the dorsal medial habenula. 

“Traditional methods of stimulation could not isolate this part of the brain,” Turner said. “But cutting-edge technology at Seattle Children’s Research Institute makes discoveries like this possible.” 

As a professor in the University of Washington Department of Psychiatry and Behavioral Sciences, Dr. Turner treats depression and hopes this research will make a difference in the lives of future patients. 

“Working in mental health can be frustrating,” Turner said. “We have not made a lot of progress in developing new treatments. I hope the more we can learn about how the brain functions the more we can help people with all kinds of mental illness.”

Filed under motivation habenula exercise depression optogenetics neuroscience science

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Difficulty assessing effort drives motivation deficits in schizophrenia

Individuals with schizophrenia often have trouble engaging in daily tasks or setting goals for themselves, and a new study from San Francisco State University suggests the reason might be their difficulty in assessing the amount of effort required to complete tasks.

The research, detailed in an article published this week in the Journal of Abnormal Psychology, can assist health professionals in countering motivation deficits among patients with schizophrenia and help those patients function normally by breaking up larger, complex tasks into smaller, easier-to-grasp ones.

"This is one of the first studies to carefully and systematically look at the daily activities of people with schizophrenia — what those people are doing, what goals are they setting for themselves," said David Gard, an associate professor of psychology at SF State who has spent years researching motivation and emotion. "We knew that people with schizophrenia were not engaging in a lot of goal-directed behavior. We just didn’t know why."

In 2011, Gard received a grant from the National Institute of Mental Health to study the reasons behind this difficulty in goal setting. An earlier article detailing other research from this study, published in May in the journal Schizophrenia Research, showed that when people with schizophrenia do set goals for themselves, they set them for the same reasons as persons without: to connect with others. But motivation deficits are still common among these individuals, and his latest study set out to pinpoint the reason.

Through a series of cognitive assessments and random phone calls, Gard and his colleagues at SF State and the University of California, San Francisco collected data from 47 people with and 41 people without schizophrenia. Participants were called four times a day, randomly throughout the day, for a week and asked about their current mood, as well as what they were doing; how much enjoyment they were getting out of it; and what their goals for the rest of the day were. The results were coded by variables such as how much pleasure they were getting out of their daily activities and how much effort was involved, then compared that with the results from the cognitive assessments.

Gard and his fellow researchers found that, while people with schizophrenia engage in low-impact, pleasurable goals — such as watching TV or eating food for enjoyment — as much as others, they have greater difficulty with more complex undertakings or goals requiring more effort.

"There’s something breaking down in the process around assessing high-effort, high-reward goals," Gard said. "When the reward is high and the effort is high, that’s when people with schizophrenia struggle to hold in mind and go after the thing that they want for themselves."

The findings indicate that health-care providers who want to help individuals with schizophrenia set goals for themselves should break larger tasks into smaller, simpler ones with small rewards. For example, instead of guiding a patient specifically toward the larger goal of getting in physical shape, a provider could instead encourage them to gradually walk a little bit more every day.

"That’s something we would do for everyone else, but it might have been avoided in patients with schizophrenia because we thought they weren’t experiencing as much pleasure from their activities as they actually are," Gard added. "We can help them to identify things that are pleasurable and reward them toward larger goals."

(Source: news.sfsu.edu)

Filed under schizophrenia motivation goal-directed behavior psychology neuroscience science

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Study reveals brain mechanism behind chronic pain’s sapping of motivation

Chronic pain is among the most abundant of all medical afflictions in the developed world. It differs from a short-term episode of pain not only in its duration, but also in triggering in its sufferers a psychic exhaustion best described by the question, “Why bother?”

A new study in mice, conducted by investigators at the Stanford University School of Medicine, has identified a set of changes in key parts of the brain that may explain chronic pain’s capacity to stifle motivation. The discovery could lead to entirely new classes of treatment for this damaging psychological consequence of chronic pain.

Many tens of millions of people in the United States suffer persistent pain due to diverse problems including migraines, arthritis, lower back pain, sports injuries, irritable bowel syndrome and shingles. For many of these conditions, there are no good treatments, and a crippling loss of mojo can result.

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“With chronic pain, your whole life changes in a way that doesn’t happen with acute pain,” said Robert Malenka, MD, PhD, the Nancy Friend Pritzker Professor in Psychiatry and Behavioral Sciences and the study’s senior author. “Yet this absence of motivation caused by chronic pain, which can continue even when the pain is transiently relieved, has been largely ignored by medical science.”

A series of experiments in mice by Malenka and his colleagues, described in a study published Aug. 1 in Science, showed that persistent pain causes changes in a set of nerve cells in a deep-brain structure known to be important in reward-seeking behavior: the pursuit of goals likely to yield pleasurable results. Malenka’s lab has been studying this brain structure, the nucleus accumbens, for two decades.

“We showed that those brain changes don’t go away when you transiently relieve the mice’s pain,” Malenka said. The experiments also indicated that the mice’s diminished motivation to perform reward-generating tasks didn’t stem from their pain’s rendering them incapable of experiencing pleasure or from any accompanying physical impairment, he said.

How pain and reward interact

“This study is important — to my knowledge, the first to explain how pain and reward interact. It begins to get to an understanding of why it’s such a struggle for people undergoing chronic pain to get through the day,” said Howard Fields, MD, PhD, a professor of neurology at the University of California-San Francisco and founder of that school’s pain management center.

Fields, who did not participate in the Malenka group’s study but wrote an accompanying perspective piece published simultaneously in Science, described the psychological effect of chronic pain as “the clouding of the future. There’s no escape from it. You want it to end, but it doesn’t.” As a result, people become pessimistic and irritable, he said. “People come to expect the next day is going to wind up being painful. It just takes the edge off of life’s little pleasures — and big pleasures, for that matter.”

The experiments were spearheaded by the study’s first author, Neil Schwartz, PhD, a postdoctoral scholar in Malenka’s lab. “You can’t just ask a hungry mouse how motivated it is to pursue its heart’s desire,” Malenka said. “But there are ways of asking that mouse, ‘How hard are you willing to work for food?’”

Schwartz, Malenka and their associates looked at lab mice enduring chronic paw pain due either to persistent inflammation or to nerve damage. The mice also happened to be hungry. The scientists trained the mice to poke their noses into a hole to get a food pellet. At first, a single nose poke earned a pellet. But over time, the number of nose pokes required for a reward was increased. In essence, the researchers were asking these mice: How hard are you willing to work for food? Will you poke your nose into that hole once to satisfy your hunger? Ten times? Even 150 times?

Fading motivation

Within a week after the onset of chronic pain, the animals grew increasingly less likely to work hard for food than pain-free control animals were. The researchers next explored three possible explanations: Were the mice unable to work because their pain was too severe? Did something about being in pain cause them to not value the food reward as much? Or was their failure to seek food due simply to a lack of motivation? Additional tests showed that the mice had no movement problems. “Like other research groups, we found that they can scamper around just fine,” said Malenka. Also, when the mice were given free access to food, they ate just as much as the animals who weren’t in pain — so they still valued the food. But they were less willing to put in an effort to obtain food than mice who’d suffered no pain.

Moreover, the difference didn’t disappear even when the scientists relieved the mice’s pain with analgesics. “They were in demonstrably less pain, but they were still less willing to work,” Malenka said.

The Stanford scientists then focused on the nucleus accumbens, a brain structure known to be involved in computing the behavioral strategies that prompt us to seek or avoid things that can affect our survival. They found that chronic pain permanently changed certain connections to the nucleus accumbens, causing an enduring downshift in the excitation transmitted by them. Importantly, Malenka’s group showed that a particular brain chemical called galanin plays a critical role in this enduring suppression of nucleus accumbens excitability.

Galanin is a short signaling-protein snippet secreted by certain cells in various places in the brain. While its presence in the brain has been known for a good 60 years or so, galanin’s role is not well-defined and probably differs widely in different brain structures. There have been hints, though, that galanin activity might play a role in pain. For example, it’s been previously shown in animal models that galanin levels in the brain increase with the persistence of pain.

Possible therapies?

Schwartz, Malenka and their peers identified receptors for galanin on a set of nerve cells in the nucleus accumbens and demonstrated that disabling galanin’s signaling via this receptor prevented the long-term suppression of motivation seen in mice — and people — with chronic pain. This suggests that therapeutic compounds with similar effects could someday be developed, although they would have to be carefully targeted so as to not disrupt galanin signaling in other important brain circuits.

“There’s no reason to think this finding won’t generalize to people,” said Fields of UCSF. “Our brains have galanin, and a nucleus accumbens, just as mouse brains do. However, before jumping from mice to humans it would be wise to test other animal species. If the same things happen in a non-rodent species that happen in mice, then it’s probable they happen in humans, too.”

(Source: med.stanford.edu)

Filed under pain chronic pain motivation reward nucleus accumbens neuroscience science

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Brain activity in sex addiction mirrors that of drug addiction Pornography triggers brain activity in people with compulsive sexual behaviour – known commonly as sex addiction – similar to that triggered by drugs in the brains of drug addicts, according to a University of Cambridge study published in the journal PLOS ONE. However, the researchers caution that this does not necessarily mean that pornography itself is addictive. Although precise estimates are unknown, previous studies have suggested that as many as one in 25 adults is affected by compulsive sexual behaviour, an obsession with sexual thoughts, feelings or behaviour which they are unable to control. This can have an impact on a person’s personal life and work, leading to significant distress and feelings of shame. Excessive use of pornography is one of the main features identified in many people with compulsive sexual behaviour. However, there is currently no formally accepted definition of diagnosing the condition. In a study funded by the Wellcome Trust, researchers from the Department of Psychiatry at the University of Cambridge looked at brain activity in nineteen male patients affected by compulsive sexual behaviour and compared them to the same number of healthy volunteers. The patients started watching pornography at earlier ages and in higher proportions relative to the healthy volunteers. “The patients in our trial were all people who had substantial difficulties controlling their sexual behaviour and this was having significant consequences for them, affecting their lives and relationships,” explains Dr Valerie Voon, a Wellcome Trust Intermediate Clinical Fellow at the University of Cambridge. “In many ways, they show similarities in their behaviour to patients with drug addictions. We wanted to see if these similarities were reflected in brain activity, too.” The study participants were shown a series of short videos featuring either sexually explicit content or sports whilst their brain activity was monitored using functional magnetic resonance imaging (fMRI), which uses a blood oxygen level dependent (BOLD) signal to measure brain activity. The researchers found that three regions in particular were more active in the brains of the people with compulsive sexual behaviour compared with the healthy volunteers. Significantly, these regions – the ventral striatum, dorsal anterior cingulate and amygdala – were regions that are also particularly activated in drug addicts when shown drug stimuli. The ventral striatum is involved in processing reward and motivation, whilst the dorsal anterior cingulate is implicated in anticipating rewards and drug craving. The amygdala is involved in processing the significance of events and emotions. The researchers also asked the participants to rate the level of sexual desire that they felt whilst watching the videos, and how much they liked the videos. Drug addicts are thought to be driven to seek their drug because they want – rather than enjoy – it. This abnormal process is known as incentive motivation, a compelling theory in addiction disorders. As anticipated, patients with compulsive sexual behaviour showed higher levels of desire towards the sexually explicit videos, but did not necessarily rate them higher on liking scores. In the patients, desire was also correlated with higher interactions between regions within the network identified – with greater cross-talk between the dorsal cingulate, ventral striatum and amygdala – for explicit compared to sports videos. Dr Voon and colleagues also found a correlation between brain activity and age – the younger the patient, the greater the level of activity in the ventral striatum in response to pornography. Importantly, this association was strongest in individuals with compulsive sexual behaviour. The frontal control regions of the brain – essentially, the ‘brakes’ on our compulsivity – continue to develop into the mid-twenties and this imbalance may account for greater impulsivity and risk taking behaviours in younger people. The age-related findings in individuals with compulsive sexual behaviours suggest that the ventral striatum may be important in developmental aspects of compulsive sexual behaviours in a similar fashion as it is in drug addictions, although direct testing of this possibility is needed. “There are clear differences in brain activity between patients who have compulsive sexual behaviour and healthy volunteers. These differences mirror those of drug addicts,” adds Dr Voon. “Whilst these findings are interesting, it’s important to note, however, that they could not be used to diagnose the condition. Nor does our research necessarily provide evidence that these individuals are addicted to porn – or that porn is inherently addictive. Much more research is required to understand this relationship between compulsive sexual behaviour and drug addiction.” Dr John Williams, Head of Neuroscience and Mental Health at the Wellcome Trust, says: “Compulsive behaviours, including watching porn to excess, over-eating and gambling, are increasingly common. This study takes us a step further to finding out why we carry on repeating behaviours that we know are potentially damaging to us. Whether we are tackling sex addiction, substance abuse or eating disorders, knowing how best, and when, to intervene in order to break the cycle is an important goal of this research.”

Brain activity in sex addiction mirrors that of drug addiction

Pornography triggers brain activity in people with compulsive sexual behaviour – known commonly as sex addiction – similar to that triggered by drugs in the brains of drug addicts, according to a University of Cambridge study published in the journal PLOS ONE. However, the researchers caution that this does not necessarily mean that pornography itself is addictive.

Although precise estimates are unknown, previous studies have suggested that as many as one in 25 adults is affected by compulsive sexual behaviour, an obsession with sexual thoughts, feelings or behaviour which they are unable to control. This can have an impact on a person’s personal life and work, leading to significant distress and feelings of shame. Excessive use of pornography is one of the main features identified in many people with compulsive sexual behaviour. However, there is currently no formally accepted definition of diagnosing the condition.

In a study funded by the Wellcome Trust, researchers from the Department of Psychiatry at the University of Cambridge looked at brain activity in nineteen male patients affected by compulsive sexual behaviour and compared them to the same number of healthy volunteers. The patients started watching pornography at earlier ages and in higher proportions relative to the healthy volunteers.

“The patients in our trial were all people who had substantial difficulties controlling their sexual behaviour and this was having significant consequences for them, affecting their lives and relationships,” explains Dr Valerie Voon, a Wellcome Trust Intermediate Clinical Fellow at the University of Cambridge. “In many ways, they show similarities in their behaviour to patients with drug addictions. We wanted to see if these similarities were reflected in brain activity, too.”

The study participants were shown a series of short videos featuring either sexually explicit content or sports whilst their brain activity was monitored using functional magnetic resonance imaging (fMRI), which uses a blood oxygen level dependent (BOLD) signal to measure brain activity.

The researchers found that three regions in particular were more active in the brains of the people with compulsive sexual behaviour compared with the healthy volunteers. Significantly, these regions – the ventral striatum, dorsal anterior cingulate and amygdala – were regions that are also particularly activated in drug addicts when shown drug stimuli. The ventral striatum is involved in processing reward and motivation, whilst the dorsal anterior cingulate is implicated in anticipating rewards and drug craving. The amygdala is involved in processing the significance of events and emotions.

The researchers also asked the participants to rate the level of sexual desire that they felt whilst watching the videos, and how much they liked the videos. Drug addicts are thought to be driven to seek their drug because they want – rather than enjoy – it. This abnormal process is known as incentive motivation, a compelling theory in addiction disorders.

As anticipated, patients with compulsive sexual behaviour showed higher levels of desire towards the sexually explicit videos, but did not necessarily rate them higher on liking scores. In the patients, desire was also correlated with higher interactions between regions within the network identified – with greater cross-talk between the dorsal cingulate, ventral striatum and amygdala – for explicit compared to sports videos.

Dr Voon and colleagues also found a correlation between brain activity and age – the younger the patient, the greater the level of activity in the ventral striatum in response to pornography. Importantly, this association was strongest in individuals with compulsive sexual behaviour. The frontal control regions of the brain – essentially, the ‘brakes’ on our compulsivity – continue to develop into the mid-twenties and this imbalance may account for greater impulsivity and risk taking behaviours in younger people. The age-related findings in individuals with compulsive sexual behaviours suggest that the ventral striatum may be important in developmental aspects of compulsive sexual behaviours in a similar fashion as it is in drug addictions, although direct testing of this possibility is needed.

“There are clear differences in brain activity between patients who have compulsive sexual behaviour and healthy volunteers. These differences mirror those of drug addicts,” adds Dr Voon. “Whilst these findings are interesting, it’s important to note, however, that they could not be used to diagnose the condition. Nor does our research necessarily provide evidence that these individuals are addicted to porn – or that porn is inherently addictive. Much more research is required to understand this relationship between compulsive sexual behaviour and drug addiction.”

Dr John Williams, Head of Neuroscience and Mental Health at the Wellcome Trust, says: “Compulsive behaviours, including watching porn to excess, over-eating and gambling, are increasingly common. This study takes us a step further to finding out why we carry on repeating behaviours that we know are potentially damaging to us. Whether we are tackling sex addiction, substance abuse or eating disorders, knowing how best, and when, to intervene in order to break the cycle is an important goal of this research.”

Filed under addiction compulsive sexual behavior brain activity amygdala motivation neuroscience science

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Understanding Binge Eating and Obesity Researchers at the University of Cambridge have developed a novel method for evaluating the treatment of obesity-related food behavior. In an effort to further scientific understanding of the underlying problem, they have published the first peer-reviewed video of their technique in JoVE, the Journal of Visualized Experiments. In the video, the authors demonstrate their means of objectively studying the drivers and mechanisms of overconsumption in humans. To do this, they assesses their subject’s willingness to work or pay for food, and they simultaneously track the corresponding brain activity using an MRI scanner. “We present alternative ways of exploring attitudes to food by using indirect, objective measures—such as measuring the amount of energy exerted to obtain or view different foods, as well as determining brain responses during the anticipation and consumption of desirable foods,” said the lab’s principal investigator, Dr. Paul Fletcher. He and his colleagues use participant hand-grip intensity (referred to as “grip force” in the video) to calculate the motivation for a given food reward. According to Dr. Fletcher, typical approaches for evaluating anti-obesity type drugs rely on more subjective methods—like having test subjects self-report their ratings of hunger and cravings.   “When a person is asked how much they subjectively desire a food, they may feel pressured to give a ‘correct’ rather than a true answer,” said Dr. Fletcher, “[Our] grip force task may, under certain circumstances, present a more accurate reflection of what they really want.” Dr. Fletcher and his colleagues brought the technique to JoVE after using it in their earlier publication, “Food images engage subliminal motivation to seek food,” published in 2011. They decided to publish a video capturing the protocol “Because it offered the opportunity to demonstrate the methods more fully,” he said. In the video, Dr. Fletcher expands on the purpose of publishing the method with JoVE. “Individuals new to the technique may struggle because there aren’t many examples of grip-force tasks published in the literature, and there are no full and clear descriptions of how to design and set up the tasks,” he said. With rising concerns surrounding obesity, researchers can use the technique presented in the JoVE video to determine the efficacy of a potential emerging market in anti-obesity medicine.

Understanding Binge Eating and Obesity

Researchers at the University of Cambridge have developed a novel method for evaluating the treatment of obesity-related food behavior. In an effort to further scientific understanding of the underlying problem, they have published the first peer-reviewed video of their technique in JoVE, the Journal of Visualized Experiments.

In the video, the authors demonstrate their means of objectively studying the drivers and mechanisms of overconsumption in humans. To do this, they assesses their subject’s willingness to work or pay for food, and they simultaneously track the corresponding brain activity using an MRI scanner.

“We present alternative ways of exploring attitudes to food by using indirect, objective measures—such as measuring the amount of energy exerted to obtain or view different foods, as well as determining brain responses during the anticipation and consumption of desirable foods,” said the lab’s principal investigator, Dr. Paul Fletcher. He and his colleagues use participant hand-grip intensity (referred to as “grip force” in the video) to calculate the motivation for a given food reward.

According to Dr. Fletcher, typical approaches for evaluating anti-obesity type drugs rely on more subjective methods—like having test subjects self-report their ratings of hunger and cravings.  

“When a person is asked how much they subjectively desire a food, they may feel pressured to give a ‘correct’ rather than a true answer,” said Dr. Fletcher, “[Our] grip force task may, under certain circumstances, present a more accurate reflection of what they really want.”

Dr. Fletcher and his colleagues brought the technique to JoVE after using it in their earlier publication, “Food images engage subliminal motivation to seek food,” published in 2011. They decided to publish a video capturing the protocol “Because it offered the opportunity to demonstrate the methods more fully,” he said.

In the video, Dr. Fletcher expands on the purpose of publishing the method with JoVE. “Individuals new to the technique may struggle because there aren’t many examples of grip-force tasks published in the literature, and there are no full and clear descriptions of how to design and set up the tasks,” he said.

With rising concerns surrounding obesity, researchers can use the technique presented in the JoVE video to determine the efficacy of a potential emerging market in anti-obesity medicine.

Filed under binge eating obesity motivation reward processing food reward decision making psychology neuroscience science

145 notes

Overlapping Neural Systems Represent Cognitive Effort and Reward Anticipation Anticipating a potential benefit and how difficult it will be to obtain it are valuable skills in a constantly changing environment. In the human brain, the anticipation of reward is encoded by the Anterior Cingulate Cortex (ACC) and Striatum. Naturally, potential rewards have an incentive quality, resulting in a motivational effect improving performance. Recently it has been proposed that an upcoming task requiring effort induces a similar anticipation mechanism as reward, relying on the same cortico-limbic network. However, this overlapping anticipatory activity for reward and effort has only been investigated in a perceptual task. Whether this generalizes to high-level cognitive tasks remains to be investigated. To this end, an fMRI experiment was designed to investigate anticipation of reward and effort in cognitive tasks. A mental arithmetic task was implemented, manipulating effort (difficulty), reward, and delay in reward delivery to control for temporal confounds. The goal was to test for the motivational effect induced by the expectation of bigger reward and higher effort. The results showed that the activation elicited by an upcoming difficult task overlapped with higher reward prospect in the ACC and in the striatum, thus highlighting a pivotal role of this circuit in sustaining motivated behavior. Full article

Overlapping Neural Systems Represent Cognitive Effort and Reward Anticipation

Anticipating a potential benefit and how difficult it will be to obtain it are valuable skills in a constantly changing environment. In the human brain, the anticipation of reward is encoded by the Anterior Cingulate Cortex (ACC) and Striatum. Naturally, potential rewards have an incentive quality, resulting in a motivational effect improving performance. Recently it has been proposed that an upcoming task requiring effort induces a similar anticipation mechanism as reward, relying on the same cortico-limbic network. However, this overlapping anticipatory activity for reward and effort has only been investigated in a perceptual task. Whether this generalizes to high-level cognitive tasks remains to be investigated. To this end, an fMRI experiment was designed to investigate anticipation of reward and effort in cognitive tasks. A mental arithmetic task was implemented, manipulating effort (difficulty), reward, and delay in reward delivery to control for temporal confounds. The goal was to test for the motivational effect induced by the expectation of bigger reward and higher effort. The results showed that the activation elicited by an upcoming difficult task overlapped with higher reward prospect in the ACC and in the striatum, thus highlighting a pivotal role of this circuit in sustaining motivated behavior.

Full article

Filed under neuroimaging reward processing reward motivation performance cingulate cortex psychology neuroscience science

144 notes

Brain discovery could help schizophrenics The discovery of brain impairment in mice may eventually lead to better therapies for people with schizophrenia and major depression. Studying rodents that have a gene associated with mental illness, Michigan State University neuroscientist Alexander Johnson and colleagues found a link between a specific area of the prefrontal cortex, and learning and behavioral deficits. While much work needs to be done, the discovery is a major step toward better understanding mental illness. While antipsychotic drugs can treat hallucinations related to schizophrenia, there essentially is no treatment for other symptoms such as lack of motivation or anhedonia, the inability to experience pleasure. “This study may well suggest that if we start targeting these brain-behavior mechanisms in people with mental illness, it may help to alleviate some of the cognitive and motivational symptoms, which to date remain largely untreated with current drug therapies,” said Johnson, MSU assistant professor of psychology. The study is published in the Proceedings of the National Academy of Sciences. Schizophrenia, a disabling brain disorder marked by paranoia and hearing voices that aren’t there, affects some 2.4 million Americans and runs in families, according to the National Institute of Mental Health. The researchers conducted a series of experiments with two groups of mice – those with the gene associated with mental illness and those without the gene (or the control group). In one experiment, related to cognition, the mice were presented with tasty food when they responded on one side of a conditioning box. After repeated feedings, the food was switched to the other side of the box. The mice with the mental illness gene had a much more difficult time learning to adapt to the new side. In another experiment, related to motivation, the mice had to respond an increasing number of times each time they wanted food. By the end of the three-hour session, all mice with the mental illness gene stopped responding for food, while half of the control group continued on. Johnson said the deficiencies may suggest a problem in the prefrontal cortex area known as the orbitofrontal cortex, and that further research should target this area.

Brain discovery could help schizophrenics

The discovery of brain impairment in mice may eventually lead to better therapies for people with schizophrenia and major depression.

Studying rodents that have a gene associated with mental illness, Michigan State University neuroscientist Alexander Johnson and colleagues found a link between a specific area of the prefrontal cortex, and learning and behavioral deficits.

While much work needs to be done, the discovery is a major step toward better understanding mental illness. While antipsychotic drugs can treat hallucinations related to schizophrenia, there essentially is no treatment for other symptoms such as lack of motivation or anhedonia, the inability to experience pleasure.

“This study may well suggest that if we start targeting these brain-behavior mechanisms in people with mental illness, it may help to alleviate some of the cognitive and motivational symptoms, which to date remain largely untreated with current drug therapies,” said Johnson, MSU assistant professor of psychology.

The study is published in the Proceedings of the National Academy of Sciences.

Schizophrenia, a disabling brain disorder marked by paranoia and hearing voices that aren’t there, affects some 2.4 million Americans and runs in families, according to the National Institute of Mental Health.

The researchers conducted a series of experiments with two groups of mice – those with the gene associated with mental illness and those without the gene (or the control group).

In one experiment, related to cognition, the mice were presented with tasty food when they responded on one side of a conditioning box. After repeated feedings, the food was switched to the other side of the box. The mice with the mental illness gene had a much more difficult time learning to adapt to the new side.

In another experiment, related to motivation, the mice had to respond an increasing number of times each time they wanted food. By the end of the three-hour session, all mice with the mental illness gene stopped responding for food, while half of the control group continued on.

Johnson said the deficiencies may suggest a problem in the prefrontal cortex area known as the orbitofrontal cortex, and that further research should target this area.

Filed under orbitofrontal cortex schizophrenia learning motivation psychology neuroscience science

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The motivation to move: Study finds rats calculate ‘average’ of reward across several tests Suppose you had $1,000 to invest in the stock market. How would you decide to pick one stock over another? Scientists have made great progress in understanding the neuroscience behind how people choose between similar options. But what happens when neither choice is right? During an economic downturn, for instance, your best option might be not to invest at all, but to wait for market conditions to improve. Using an unusual decision-making study, Harvard researchers exploring the question of motivation found that rats will perform a task faster or slower depending on the size of the benefit they receive, suggesting that they maintain a long-term estimate of whether it’s worth it to them to invest energy in a task. As described in an April 14 paper in Nature Neuroscience, a research team led by Naoshige Uchida, associate professor of molecular and cellular biology, found that rats averaged how much benefit they received over as many as five trials. When their brains were impaired in one region, however, the rats based their actions solely on the prior trial. “This is a new framework to think about decision-making,” Uchida said. “There have been many studies that focused on action selection or choices, but the question of the overall pace or rate of performance has been largely ignored.” To get at those decision-making questions, Uchida and his team designed the experiment. In each trial, rats were presented with an apparatus that had three holes. Based on whether a sweet or sour odor was delivered through the middle hole, rats went either left or right to receive a water reward. On one side they received a large reward; the other side delivered a smaller reward. “What we measured was, after getting the reward, how quickly they went back to initiate the next trial,” Uchida said. What researchers found, Uchida said, was surprising. When rats received, on average, a larger reward, they were more likely to quickly initiate the next trial, which suggested that they weren’t reacting merely to the prior result, but were “averaging the size of the reward from several previous trials.” “They essentially calculate the average over the previous five or six trials, and adjust their performance accordingly,” Uchida said. “They’re making a calculation to determine whether they’re getting something out of the task or not. If it’s worth it for them, they go faster. If not, they go slower.” When researchers impaired part of the striatum, a brain structure that is part of the basal ganglia and is thought to be involved with associative thinking, in the rats’ brains, however, that calculation changed. Rather than considering the average of multiple trials, the rats chose whether to go slower or faster based solely on the prior result. “They still go faster or slower depending on the size of the reward, but they base that decision only on the size of the reward they just got,” Uchida said. “So the rat becomes very myopic. They only care about what just happened, and they don’t take other trials into account.” In addition to shedding new light on how decision-making happens, the study may also offer some hope for people suffering from Parkinson’s disease. “This part of the striatum receives a great deal of inputs from dopamine neurons, so it may be related to Parkinson’s disease,” Uchida said. “Some people now think Parkinson’s may actually be related to the motivation, or ‘vigor’ to perform some movement. So if we can identify brain regions that are involved in the regulation of general motivation, it’s possible that it could be contributing to the symptoms of Parkinson’s disease.” Going forward, Uchida said, he hopes to study the role dopamine plays in regulating motivation and decision making, as well as working to understand what role other areas of the striatum might play in the process. “There are some interesting similarities between this part of the striatum in rats and in humans,” he said. “One is that this area receives very heavy inputs from the prefrontal cortex. That’s an area that may be important in integrating information over a longer period of time. Deconstructing this process is a critical step to understanding our behavior, and this could go a long way toward that.”

The motivation to move: Study finds rats calculate ‘average’ of reward across several tests

Suppose you had $1,000 to invest in the stock market. How would you decide to pick one stock over another? Scientists have made great progress in understanding the neuroscience behind how people choose between similar options.

But what happens when neither choice is right?

During an economic downturn, for instance, your best option might be not to invest at all, but to wait for market conditions to improve.

Using an unusual decision-making study, Harvard researchers exploring the question of motivation found that rats will perform a task faster or slower depending on the size of the benefit they receive, suggesting that they maintain a long-term estimate of whether it’s worth it to them to invest energy in a task.

As described in an April 14 paper in Nature Neuroscience, a research team led by Naoshige Uchida, associate professor of molecular and cellular biology, found that rats averaged how much benefit they received over as many as five trials. When their brains were impaired in one region, however, the rats based their actions solely on the prior trial.

“This is a new framework to think about decision-making,” Uchida said. “There have been many studies that focused on action selection or choices, but the question of the overall pace or rate of performance has been largely ignored.”

To get at those decision-making questions, Uchida and his team designed the experiment.

In each trial, rats were presented with an apparatus that had three holes. Based on whether a sweet or sour odor was delivered through the middle hole, rats went either left or right to receive a water reward. On one side they received a large reward; the other side delivered a smaller reward.

“What we measured was, after getting the reward, how quickly they went back to initiate the next trial,” Uchida said.

What researchers found, Uchida said, was surprising. When rats received, on average, a larger reward, they were more likely to quickly initiate the next trial, which suggested that they weren’t reacting merely to the prior result, but were “averaging the size of the reward from several previous trials.”

“They essentially calculate the average over the previous five or six trials, and adjust their performance accordingly,” Uchida said. “They’re making a calculation to determine whether they’re getting something out of the task or not. If it’s worth it for them, they go faster. If not, they go slower.”

When researchers impaired part of the striatum, a brain structure that is part of the basal ganglia and is thought to be involved with associative thinking, in the rats’ brains, however, that calculation changed. Rather than considering the average of multiple trials, the rats chose whether to go slower or faster based solely on the prior result.

“They still go faster or slower depending on the size of the reward, but they base that decision only on the size of the reward they just got,” Uchida said. “So the rat becomes very myopic. They only care about what just happened, and they don’t take other trials into account.”

In addition to shedding new light on how decision-making happens, the study may also offer some hope for people suffering from Parkinson’s disease.

“This part of the striatum receives a great deal of inputs from dopamine neurons, so it may be related to Parkinson’s disease,” Uchida said. “Some people now think Parkinson’s may actually be related to the motivation, or ‘vigor’ to perform some movement. So if we can identify brain regions that are involved in the regulation of general motivation, it’s possible that it could be contributing to the symptoms of Parkinson’s disease.”

Going forward, Uchida said, he hopes to study the role dopamine plays in regulating motivation and decision making, as well as working to understand what role other areas of the striatum might play in the process.

“There are some interesting similarities between this part of the striatum in rats and in humans,” he said. “One is that this area receives very heavy inputs from the prefrontal cortex. That’s an area that may be important in integrating information over a longer period of time. Deconstructing this process is a critical step to understanding our behavior, and this could go a long way toward that.”

Filed under brain motivation decision-making reward striatum associative thinking rats neuroscience science

314 notes

Dopamine regulates the motivation to act The widespread belief that dopamine regulates pleasure could go down in history with the latest research results on the role of this neurotransmitter. Researchers have proved that it regulates motivation, causing individuals to initiate and persevere to obtain something either positive or negative. The neuroscience journal Neuron publishes an article by researchers at the Universitat Jaume I of Castellón that reviews the prevailing theory on dopamine and poses a major paradigm shift with applications in diseases related to lack of motivation and mental fatigue and depression, Parkinson’s, multiple sclerosis, fibromyalgia, etc. and diseases where there is excessive motivation and persistence as in the case of addictions. "It was believed that dopamine regulated pleasure and reward and that we release it when we obtain something that satisfies us, but in fact the latest scientific evidence shows that this neurotransmitter acts before that, it actually encourages us to act. In other words, dopamine is released in order to achieve something good or to avoid something evil", explains Mercè Correa. Studies had shown that dopamine is released by pleasurable sensations but also by stress, pain or loss. These research results however had been skewed to only highlight the positive influence, according to Correa. The new article is a review of the paradigm based on the data from several investigations, including those conducted over the past two decades by the Castellón group in collaboration with the John Salamone of the University of Connecticut (USA), on the role of dopamine in the motivated behaviour in animals. The level of dopamine depends on individuals, so some people are more persistent than others to achieve a goal. “Dopamine leads to maintain the level of activity to achieve what is intended. This in principle is positive, however, it will always depend on the stimuli that are sought: whether the goal is to be a good student or to abuse of drugs” says Correa. High levels of dopamine could also explain the behaviour of the so-called sensation seekers as they are more motivated to act. Application for depression and addiction To know the neurobiological parameters that make people be motivated by something is important to many areas such as work, education or health. Dopamine is now seen as a core neurotransmitter to address symptoms such as the lack of energy that occurs in diseases such as depression. “Depressed people do not feel like doing anything and that’s because of low dopamine levels,” explains Correa. Lack of energy and motivation is also related to other syndromes with mental fatigue such as Parkinson’s, multiple sclerosis or fibromyalgia, among others. In the opposite case, dopamine may be involved in addictive behaviour problems, leading to an attitude of compulsive perseverance. In this sense, Correa indicates that dopamine antagonists which have been applied so far in addiction problems probably have not worked because of inadequate treatments based on a misunderstanding of the function of dopamine.

Dopamine regulates the motivation to act

The widespread belief that dopamine regulates pleasure could go down in history with the latest research results on the role of this neurotransmitter. Researchers have proved that it regulates motivation, causing individuals to initiate and persevere to obtain something either positive or negative.

The neuroscience journal Neuron publishes an article by researchers at the Universitat Jaume I of Castellón that reviews the prevailing theory on dopamine and poses a major paradigm shift with applications in diseases related to lack of motivation and mental fatigue and depression, Parkinson’s, multiple sclerosis, fibromyalgia, etc. and diseases where there is excessive motivation and persistence as in the case of addictions.

"It was believed that dopamine regulated pleasure and reward and that we release it when we obtain something that satisfies us, but in fact the latest scientific evidence shows that this neurotransmitter acts before that, it actually encourages us to act. In other words, dopamine is released in order to achieve something good or to avoid something evil", explains Mercè Correa.

Studies had shown that dopamine is released by pleasurable sensations but also by stress, pain or loss. These research results however had been skewed to only highlight the positive influence, according to Correa. The new article is a review of the paradigm based on the data from several investigations, including those conducted over the past two decades by the Castellón group in collaboration with the John Salamone of the University of Connecticut (USA), on the role of dopamine in the motivated behaviour in animals.

The level of dopamine depends on individuals, so some people are more persistent than others to achieve a goal. “Dopamine leads to maintain the level of activity to achieve what is intended. This in principle is positive, however, it will always depend on the stimuli that are sought: whether the goal is to be a good student or to abuse of drugs” says Correa. High levels of dopamine could also explain the behaviour of the so-called sensation seekers as they are more motivated to act.

Application for depression and addiction

To know the neurobiological parameters that make people be motivated by something is important to many areas such as work, education or health. Dopamine is now seen as a core neurotransmitter to address symptoms such as the lack of energy that occurs in diseases such as depression. “Depressed people do not feel like doing anything and that’s because of low dopamine levels,” explains Correa. Lack of energy and motivation is also related to other syndromes with mental fatigue such as Parkinson’s, multiple sclerosis or fibromyalgia, among others.

In the opposite case, dopamine may be involved in addictive behaviour problems, leading to an attitude of compulsive perseverance. In this sense, Correa indicates that dopamine antagonists which have been applied so far in addiction problems probably have not worked because of inadequate treatments based on a misunderstanding of the function of dopamine.

Filed under dopamine motivation depression addiction neurotransmitters neuroscience science

282 notes

Dopamine Not About Pleasure (Anymore) To John Salamone, professor of psychology and longtime researcher of the brain chemical dopamine, scientific research can be very slow-moving. “It takes a long time for things to change in science,” he says. “It’s like pulling on the steering wheel of an ocean liner, then waiting for the huge ship to slowly turn.” Salamone has spent most of his career battling a particular long-held scientific idea: the popular notion that high levels of brain dopamine are related to experiences of pleasure. As increasing numbers of studies show, he says, the famous neurotransmitter is not responsible for pleasure, but has to do with motivation. He summarizes and comments on the evidence for this shift in thinking in a Nov. 8 review in the Cell Press journal Neuron.

Dopamine Not About Pleasure (Anymore)

To John Salamone, professor of psychology and longtime researcher of the brain chemical dopamine, scientific research can be very slow-moving.

“It takes a long time for things to change in science,” he says. “It’s like pulling on the steering wheel of an ocean liner, then waiting for the huge ship to slowly turn.”

Salamone has spent most of his career battling a particular long-held scientific idea: the popular notion that high levels of brain dopamine are related to experiences of pleasure. As increasing numbers of studies show, he says, the famous neurotransmitter is not responsible for pleasure, but has to do with motivation.

He summarizes and comments on the evidence for this shift in thinking in a Nov. 8 review in the Cell Press journal Neuron.

Filed under dopamine neurotransmitters addiction motivation neuron brain neuroscience psychology science

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