Posts tagged orbitofrontal cortex
Articles and news from the latest research reports.
Gambling with confidence: Are you sure about that?
Life is a series of decisions, ranging from the mundane to the monumental. And each decision is a gamble, carrying with it the chance to second-guess. Did I make the right turn at that light? Did I choose the right college? Was this the right job for me?
Our desire to persist along a chosen path is almost entirely determined by our confidence in the decision: when you are confident that your choice is correct, you are willing to stick it out for a lot longer.
Confidence determines much of our path through life, but what is it? Most people would describe it as an emotion or a feeling. In contrast, scientists at Cold Spring Harbor Laboratory (CSHL) have found that confidence is actually a measureable quantity, and not reserved just for humans. The team, led by CSHL Associate Professor Adam Kepecs, has identified a brain region in rats whose function is required for the animals to express confidence in their decisions.
How do we know when a rat is exhibiting confidence? The researchers devised a method to study decision making in these animals. The rats were offered an odor that they were trained to associate with one of two doors. When they chose the correct door, they were rewarded. This part was easy for the animals: their selections were almost always correct. Things got trickier when Kepecs and his team offered a mixture of the two scents, with one dominating over the other by only a very small percentage. The rats now needed to choose the door representing the dominant odor in order to get their reward – a choice that reflects their best guess.
In work published today in Neuron, the team describes how confidence can be measured simply by challenging a rat to wait for the reward to be revealed behind the door. The time they are willing wait serves as a measure of the confidence in their original decision. “We found that the rats are willing to ‘gamble’ with their time,” Kepecs explains, sometimes waiting as much as 15 seconds, which is an eternity for these animals. “This is something that we can measure and create mathematical models to explain,” says Kepecs. “The time rats are willing to wait predicts the likelihood of correct decisions and provides an objective measure to track the feeling of confidence.”
The researchers hypothesized that a distinct region of the brain might control confidence. Previous work has suggested that the orbitofrontal cortex (OFC), a part of the brain involved in making predictions, might have a role in decision confidence. Kepecs and his team specifically shut off neurons in the OFC, inactivating it, and found that rats no longer exhibited appropriate levels of confidence in their decisions.
“With an inactive OFC, the rats retained the ability to make decisions – their accuracy did not change,” says Kepecs. “And they spent the same amount of time waiting for a reward on average. The only difference is that animals’ willingness to wait for a reward was no longer guided by confidence. They would often wait a long time even when they were wrong.”
The discovery offers a rare glimpse into the neuronal basis of a higher-level cognitive process, and is likely to have implications in human decision-making as well. As Kepecs describes, “we now know that the OFC is critical for making on-the-fly predictions in rats. The human OFC is just a more sophisticated version of the rodent counterpart.” The team is expanding their research to explore how the elusive feelings of confidence are based on objective predictions that influence human decisions as well.
New Study Examines Impact of Violent Media on the Brain
With the longstanding debate over whether violent movies cause real world violence as a backstop, a study published today in PLOS One found that each person’s reaction to violent images depends on that individual’s brain circuitry, and on how aggressive they were to begin with.
The study, which was led by researchers at the Icahn School of Medicine at Mount Sinai and the NIH Intramural Program, featured brain scans which revealed that both watching and not watching violent images caused different brain activity in people with different aggression levels. The findings may have implications for intervention programs that seek to reduce aggressive behavior starting in childhood.
“Our aim was to investigate what is going on in the brains of people when they watch violent movies,” said lead investigator Nelly Alia-Klein, PhD, Associate Professor of Neuroscience and Psychiatry at the Friedman Brain Institute and Icahn School of Medicine at Mount Sinai. “We hypothesized that if people have aggressive traits to begin with, they will process violent media in a very different way as compared to non-aggressive people, a theory supported by these findings.”
After answering a questionnaire, a group of 54 men were split by the research team into two groups—one with individuals possessing aggressive traits, including a history of physical assault, and a second group without these tendencies. The participants’ brains were then scanned as they watched a succession of violent scenes (shootings and street fights) on day one, emotional, but non-violent scenes (people interacting during a natural disaster) on day two, and nothing on day three.
The scans measured the subjects’ brain metabolic activity, a marker of brain function. Participants also had their blood pressure taken every 5 minutes, and were asked how they were feeling at 15 minute intervals.
Investigators discovered that during mind wandering, when no movies were presented, the participants with aggressive traits had unusually high brain activity in a network of regions that are known to be active when not doing anything in particular. This suggests that participants with aggressive traits have a different brain function map than non-aggressive participants, researchers said.
Interestingly, while watching scenes from violent movies, the aggressive group had less brain activity than the non-aggressive group in the orbitofrontal cortex, a brain region associated by past studies with emotion-related decision making and self-control. The aggressive subjects described feeling more inspired and determined and less upset or nervous than non-aggressive participants when watching violent (day 1) versus just emotional (day 2) media. In line with these responses, while watching the violent media, aggressive participants’ blood pressure went down progressively with time while the non-aggressive participants experienced a rise in blood pressure.
“How an individual responds to their environment depends on the brain of the beholder,” said Dr. Alia-Klein. “Aggression is a trait that develops together with the nervous system over time starting from childhood; patterns of behavior become solidified and the nervous system prepares to continue the behavior patterns into adulthood when they become increasingly coached in personality. This could be at the root of the differences in people who are aggressive and not aggressive, and how media motivates them to do certain things. Hopefully these results will give educators an opportunity to identify children with aggressive traits and teach them to be more aware of how aggressive material activates them specifically.”
Scientists Find Possible Neurobiological Basis for Tradeoff Between Honesty, Self-Interest
What’s the price on your integrity? Tell the truth; everyone has a tipping point. We all want to be honest, but at some point, we’ll lie if the benefit is great enough. Now, scientists have confirmed the area of the brain in which we make that decision.
The result was published online this week in Nature Neuroscience.
(Source: newswise.com)
Study cracks how the brain processes emotions
Although feelings are personal and subjective, the human brain turns them into a standard code that objectively represents emotions across different senses, situations and even people, reports a new study by Cornell University neuroscientist Adam Anderson.
“We discovered that fine-grained patterns of neural activity within the orbitofrontal cortex, an area of the brain associated with emotional processing, act as a neural code which captures an individual’s subjective feeling,” says Anderson, associate professor of human development in Cornell’s College of Human Ecology and senior author of the study. “Population coding of affect across stimuli, modalities and individuals,” published online in Nature Neuroscience.
Their findings provide insight into how the brain represents our innermost feelings – what Anderson calls the last frontier of neuroscience – and upend the long-held view that emotion is represented in the brain simply by activation in specialized regions for positive or negative feelings, he says.
“If you and I derive similar pleasure from sipping a fine wine or watching the sun set, our results suggest it is because we share similar fine-grained patterns of activity in the orbitofrontal cortex,” Anderson says.
“It appears that the human brain generates a special code for the entire valence spectrum of pleasant-to-unpleasant, good-to-bad feelings, which can be read like a ‘neural valence meter’ in which the leaning of a population of neurons in one direction equals positive feeling and the leaning in the other direction equals negative feeling,” Anderson explains.
For the study, the researchers presented participants with a series of pictures and tastes during functional neuroimaging, then analyzed participants’ ratings of their subjective experiences along with their brain activation patterns.
Anderson’s team found that valence was represented as sensory-specific patterns or codes in areas of the brain associated with vision and taste, as well as sensory-independent codes in the orbitofrontal cortices (OFC), suggesting, the authors say, that representation of our internal subjective experience is not confined to specialized emotional centers, but may be central to perception of sensory experience.
They also discovered that similar subjective feelings – whether evoked from the eye or tongue – resulted in a similar pattern of activity in the OFC, suggesting the brain contains an emotion code common across distinct experiences of pleasure (or displeasure), they say. Furthermore, these OFC activity patterns of positive and negative experiences were partly shared across people.
“Despite how personal our feelings feel, the evidence suggests our brains use a standard code to speak the same emotional language,” Anderson concludes.
Rats show regret, a cognitive behavior once thought to be uniquely human
New research from the Department of Neuroscience at the University of Minnesota reveals that rats show regret, a cognitive behavior once thought to be uniquely and fundamentally human.
Research findings were recently published in Nature Neuroscience.
To measure the cognitive behavior of regret, A. David Redish, Ph.D., a professor of neuroscience in the University of Minnesota Department of Neuroscience, and Adam Steiner, a graduate student in the Graduate Program in Neuroscience, who led the study, started from the definitions of regret that economists and psychologists have identified in the past.
"Regret is the recognition that you made a mistake, that if you had done something else, you would have been better off," said Redish. "The difficult part of this study was separating regret from disappointment, which is when things aren’t as good as you would have hoped. The key to distinguishing between the two was letting the rats choose what to do."
Redish and Steiner developed a new task that asked rats how long they were willing to wait for certain foods. “It’s like waiting in line at a restaurant,” said Redish. “If the line is too long at the Chinese food restaurant, then you give up and go to the Indian food restaurant across the street.”
In this task, which they named “Restaurant Row,” the rat is presented with a series of food options but has limited time at each “restaurant.”
Research findings show rats were willing to wait longer for certain flavors, implying they had individual preferences. Because they could measure the rats’ individual preferences, Steiner and Redish could measure good deals and bad deals. Sometimes, the rats skipped a good deal and found themselves facing a bad deal.
"In humans, a part of the brain called the orbitofrontal cortex is active during regret. We found in rats that recognized they had made a mistake, indicators in the orbitofrontal cortex represented the missed opportunity. Interestingly, the rat’s orbitofrontal cortex represented what the rat should have done, not the missed reward. This makes sense because you don’t regret the thing you didn’t get, you regret the thing you didn’t do," said Redish.
Redish adds that results from Restaurant Row allow neuroscientists to ask additional questions to better understand why humans do things the way they do. By building upon this animal model of regret, Redish believes future research could help us understand how regret affects the decisions we make.
Sex-specific changes in cerebral blood flow begin at puberty
Puberty is the defining process of adolescent development, beginning a cascade of changes throughout the body, including the brain. Penn Medicine researchers have discovered that cerebral blood flow (CBF) levels decreased similarly in males and females before puberty, but saw them diverge sharply in puberty, with levels increasing in females while decreasing further in males, which could give hints as to developing differences in behavior in men and women and sex-specific pre-dispositions to certain psychiatric disorders. Their findings are available in Proceedings of the National Academy of Science (PNAS).
"These findings help us understand normal neurodevelopment and could be a step towards creating normal ‘growth charts’ for brain development in kids. These results also show what every parent knows: boys and girls grow differently. This applies to the brain as well," says Theodore D. Satterthwaite, MD, MA, assistant professor in the Department of Psychiatry in the Perelman School of Medicine at the University of Pennsylvania. "Hopefully, one day such growth charts might allow us to identify abnormal brain development much earlier before it leads to major mental illness."
Studies on structural brain development have shown that puberty is an important source of sex differences. Previous work has shown that CBF declines throughout childhood, but the effects of puberty on properties of brain physiology such as CBF, also known as cerebral perfusion, are not well known. “We know that adult women have higher blood flow than men, but it was not clear when that difference began, so we hypothesized that the gap between women and men would begin in adolescence and coincide with puberty,” Satterthwaite says.
The Penn team imaged the brains of 922 youth ages 8 through 22 using arterial spin labeled (ASL) MRI. The youth were all members of the Philadelphia Neurodevelopmental Cohort, a National Institute of Mental Health-funded collaboration between the University of Pennsylvania Brain Behavior Laboratory and the Center for Applied Genomics at the Children’s Hospital of Philadelphia.
They found support for their hypothesis.
Age related differences were observed in the amount and location of blood flow in males versus females, with blood flow declining at a similar rate before puberty and diverging markedly in mid-puberty. At around age 16, while male CBF values continue to decline with advanced age, females CBF values actually increased. This resulted in females having notably higher CBF than males by the end of adolescence. The difference between males and females was most notable in parts of the brain that are critical for social behaviors and emotion regulation such as the orbitofrontal cortex. The researchers speculate that such differences could be related to females’ well-established superior performance on social cognition tasks. Potentially, these effects could also be related to the higher risk in women for depression and anxiety disorders, and higher risk of flat affect and schizophrenia in men.
(Source: eurekalert.org)
Brain imaging study reveals what makes some people more susceptible to peer influence
A brain area activated by group decisions can distinguish people more likely to conform to the will of a group, say researchers from UCL.
The team, led by Dr Tali Sharot, UCL Affective Brain Lab, monitored the brain activity of individuals in groups of five people choosing food or drink they’d like to consume before and after being told the most popular choice in their group.
The results showed that people were likely to conform to the most popular choice in their group if their original preference was different.
Caroline Charpentier (UCL Institute of Cognitive Neuroscience) said: “Most people don’t think their everyday decisions, such as having eggs on toast for breakfast or a pint of lager at the pub, are influenced by other people’s preferences.”
She added: “But our results suggest that when other people make different choices than you, for example your friends order beer while you order wine, your brain records this information and this signal is mirrored in your brain later on, for example when you order another drink, making you more likely to choose beer, even if you initially preferred wine”.
The team, led by Dr Tali Sharot, used functional magnetic resonance imaging (fMRI) to monitor the brain responses of 20 volunteers during a decision-making task, while 78 more volunteers completed the task simultaneously on computers located outside the MRI room. They came to the lab in small groups of five.
In one session, volunteers were shown 60 pairs of food and drink items and asked to select which item of each pair they would prefer to consume at the end of the experiment. Straight after making this choice, the participants were told which item most people in their group selected. This part of the experiment provided the volunteers with social feedback.
Volunteers then took part in a following session a few minutes later, when they opted again for which item they would prefer to consume from the same series of pairs, but this time made the choice for themselves and did not receive any social feedback.
After the experiment, the participants completed a personality questionnaire that assessed trait conformity, which measures their general tendency to follow other people’s ideas and behaviours. Comparison of results from the choice experiment and conformity questionnaire indeed showed that people who scored high on trait conformity were about twice as likely to change their food choices to agree with the group decision as people who scored low for conformity.
What differed between the brains of people who were more likely to conform and people who held on to their own opinion?
The imaging study showed that the orbito-frontal cortex (OFC) – a region at the front of the brain that has been associated with emotional and social behaviour – was active during the two choice sessions and distinguished between these two groups of people.
Miss Charpentier said: “The orbito-frontal cortex was the only region specifically activated, and the first area to react to group disagreement. This region was activated both at the time of the initial social conflict (when your friends all choose beer while you prefer wine) and also later when you make an individual choice (when you order another drink for yourself).”
The OFC has previously been associated with emotions and social behaviour. Some clinical studies have suggested that people with brain damage in the OFC may behave inappropriately in groups.
Miss Charpentier concluded: “When OFC activity during the initial social conflict is mirrored in your brain at a later time when you make an individual choice, you are more likely to change your choice and follow the group. This is what happens in ‘high conformers’. In other words, it is the temporal dynamics of the OFC that distinguishes “conformers” from people who hold on to their own initial opinion”.
(Source: ucl.ac.uk)
Brain scans show what makes us drink water and what makes us stop drinking
Drinking water when you’re thirsty is a pleasurable experience. Continuing to drink when you’re not, however, can be very unpleasant. To understand why your reaction to water drinking changes as your thirst level changes, Pascal Saker of the University of Melbourne and his colleagues performed fMRI scans on people as they drank water. They found that regions of the brain associated with positive feelings became active when the subjects were thirsty, while regions associated with negative feelings and with controlling and coordinating movement became active after the subjects were satiated. The research appears in the Proceedings of the National Academy of Sciences.
Mathematical beauty activates same brain region as great art or music
People who appreciate the beauty of mathematics activate the same part of their brain when they look at aesthetically pleasing formula as others do when appreciating art or music, suggesting that there is a neurobiological basis to beauty.
There are many different sources of beauty - a beautiful face, a picturesque landscape, a great symphony are all examples of beauty derived from sensory experiences. But there are other, highly intellectual sources of beauty. Mathematicians often describe mathematical formulae in emotive terms and the experience of mathematical beauty has often been compared by them to the experience of beauty derived from the greatest art.
In a new paper published in the open-access journal Frontiers in Human Neuroscience, researchers used functional magnetic resonance imaging (fMRI) to image the brain activity of 15 mathematicians when they viewed mathematical formulae that they had previously rated as beautiful, neutral or ugly.
The results showed that the experience of mathematical beauty correlates with activity in the same part of the emotional brain – namely the medial orbito-frontal cortex – as the experience of beauty derived from art or music.
Professor Semir Zeki, lead author of the paper from the Wellcome Laboratory of Neurobiology at UCL, said: “To many of us mathematical formulae appear dry and inaccessible but to a mathematician an equation can embody the quintescence of beauty. The beauty of a formula may result from simplicity, symmetry, elegance or the expression of an immutable truth. For Plato, the abstract quality of mathematics expressed the ultimate pinnacle of beauty.”
“This makes it interesting to learn whether the experience of beauty derived from such as highly intellectual and abstract source as mathematics correlates with activity in the same part of the emotional brain as that derived from more sensory, perceptually based, sources.”
In the study, each subject was given 60 mathematical formulae to review at leisure and rate on a scale of -5 (ugly) to +5 (beautiful) according to how beautiful they experienced them to be. Two weeks later they were asked to re-rate them while in an fMRI scanner.
The formulae most consistently rated as beautiful (both before and during the scans) were Leonhard Euler’s identity, the Pythagorean identity and the Cauchy-Riemann equations. Leonhard Euler’s identity links five fundamental mathematical constants with three basic arithmetic operations each occurring once and the beauty of this equation has been likened to that of the soliloquy in Hamlet.
Mathematicians judged Srinivasa Ramanujan’s infinite series and Riemann’s functional equation as the ugliest.
Professor Zeki said: “We have found that activity in the brain is strongly related to how intense people declare their experience of beauty to – even in this example where the source of beauty is extremely abstract. This answers a critical question in the study of aesthetics, namely whether aesthetic experiences can be quantified.”
Professor Zeki added: “We have found that, as with the experience of visual or musical beauty, the activity in the brain is strongly related to how intense people declare their experience of beauty to be – even in this example where the source of beauty is extremely abstract. This answers a critical question in the study of aesthetics, one which has been debated since classical times, namely whether aesthetic experiences can be quantified.”
Heads or tails? Random fluctuations in brain cell activity may determine toss-up decisions
Life presents us with choices all the time: salad or pizza for lunch? Tea or coffee afterward? How we make these everyday decisions has been a topic of great interest to economists, who have devised theories about how we assign values to our options and use those values to make decisions.
An emerging field of study known as neuroeconomics is combining the economists’ insights with scientific study of the brain to learn more about decision-making processes and how they can go awry. In the Dec. 8 issue of Neuron, one of the field’s founders reports new links between brain cell activity and choices where two options have equal appeal.
“Neuroeconomics is not only helpful for the development of better economic theory, it is also relevant from a clinical point of view,” said author Camillo Padoa-Schioppa, PhD, assistant professor of neurobiology, economics and of biomedical engineering at Washington University School of Medicine in St. Louis. “There are a number of conditions that involve impaired economic decision-making, including drug addiction, brain injury, some forms of dementia, schizophrenia and obsessive-compulsive disorder.”
Scientists know that the orbitofrontal cortex, a region of the brain behind and above the eyes, plays a key role in making decisions. Patients with injuries to this part of the brain are often spectacularly bad at making decisions. They may do things like abandon longstanding relationships, gamble away money or lose it to swindlers, or become addicted to drugs.
To study the roles brain cells play in decision-making, Padoa-Schioppa developed a system for presenting primates a choice between two drinks, such as grape juice or apple juice. The type and amount of the drink varies, and researchers record the activity of individual brain neurons as the primates choose.
Based on the decisions of a single animal over multiple trials, scientists infer the subjective value the animal assigns to each drink and then look for ways this value is encoded in brain cells.
“For example, if we offer a larger amount of apple juice versus a smaller amount of grape juice, and the primate chooses each option equally often, we infer that this primate likes the grape juice better than the apple juice,” he explained. “The primate could be getting more juice by choosing the cup with apple juice, but it doesn’t always do so. That implies that the primate values grape juice more than apple juice.”
In 2006, Padoa-Schioppa and Harvard colleague John Assad, PhD, won international attention for using this system to identify brain cells whose firing rates encoded the subjective value of drink choices.
In a new analysis of data from the original experiment, Padoa-Schioppa showed that different groups of cells in the orbitofrontal cortex reflect different stages of the decision-making process.
“Some neurons encode the value of individual drinks; other neurons encode the choice outcome in a binary way ‒ these cells are either firing or silent depending on the chosen drink,” he explained. “Yet other neurons encode the value of the chosen option.”
Padoa-Schioppa then examined how different groups of cells determine decisions between options of equal value. He showed that toss-up decisions seemed to depend on changes in the initial state of the network of neurons in the orbitofrontal cortex.
“The fluctuations in the network took place before the primates were even offered a choice of juices, but they seem to somehow bias the decision,” Padoa-Schioppa said. “Neuronal signals are always noisy. In essence, close-call decisions are partly determined by random noise.”
He also found that decisions on choices of equal value were linked to the ease or difficulty with which nerve cells in parts of the orbitofrontal cortex communicate with each other. This property, known as synaptic efficacy, can be adjusted by the brain as part of the process of encoding information.
According to Padoa-Schioppa, these results provide new insights into the neuronal circuits that underlie economic decisions. He and his colleagues are using them to create a computational model of decision-making.
“The next step is to test that model,” Padoa-Schioppa said. “For example, we would like to bias decisions by artificially manipulating the activity of specific groups of cells.”
(Source: news.wustl.edu)