How studying damage to the prefrontal lobe has helped unlock the brain’s mysteries

Until the last few decades, the frontal lobes of the brain were shrouded in mystery and erroneously thought of as nonessential for normal function—hence the frequent use of lobotomies in the early 20th century to treat psychiatric disorders. Now a review publishing August 28 in the Cell Press journal Neuron highlights groundbreaking studies of patients with brain damage that reveal how distinct areas of the frontal lobes are critical for a person’s ability to learn, multitask, control their emotions, socialize, and make real-life decisions. The findings have helped experts rehabilitate patients experiencing damage to this region of the brain.

Although fairly common, damage to the prefrontal lobes (also called the prefrontal cortex) is often overlooked and undiagnosed because patients do not manifest obvious deficits. For example, patients with prefrontal brain damage do not lose any of their senses and often have preserved motor and language abilities, but they may manifest social abnormalities or difficulties with high-level planning in everyday life situations.

"In this review, we aimed to highlight a blend of new studies using cutting edge research techniques to investigate brain damage, but also to relate these new studies to original studies, some of which were published more than a century ago," said lead author Dr. Sara Szczepanski, of the University of California, Berkeley. "There is currently a large push to better understand the functions of the prefrontal cortex, and we believe that our review will make an important contribution to this understanding."

In addition to revealing the functions of different areas within the prefrontal cortex, studies have also demonstrated the flexibility of the region, which has helped experts optimize cognitive therapy techniques to enable patients with brain damage to learn new skills and compensate for their impairments.

The review indicates that by studying patients with damage to the prefrontal cortex, investigators can gain insights into this still-mysterious region of the brain that is critical for complex human skills and behavior.

SA’s Taung Child’s skull and brain not human-like in expansion

The Taung Child, South Africa’s premier hominin discovered 90 years ago by Wits University Professor Raymond Dart, never seizes to transform and evolve the search for our collective origins.

By subjecting the skull of the first australopith discovered to the latest technologies in the Wits University Microfocus X-ray Computed Tomography (CT) facility, researchers are now casting doubt on theories that Australopithecus africanus shows the same cranial adaptations found in modern human infants and toddlers – in effect disproving current support for the idea that this early hominin shows infant brain development in the prefrontal region similar to that of modern humans.

The results have been published online in the prestigious journal Proceedings of the National Academy of Sciences (PNAS) on Monday, 25 August 2014 at 21:00 SAST (15:00 EST), in an article titled: New high resolution CT data of the Taung partial cranium and endocast and their bearing on metopism and hominin brain evolution.

The Taung Child has historical and scientific importance in the fossil record as the first and best example of early hominin brain evolution, and theories have been put forward that it exhibits key cranial adaptations found in modern human infants and toddlers.

To test the ancientness of this evolutionary adaptation, Dr Kristian J. Carlson, Senior Researcher from the Evolutionary Studies Institute at the University of the Witwatersrand, and colleagues, Professor Ralph L. Holloway from Columbia University and Douglas C. Broadfield from Florida Atlantic University, performed an in silico dissection of the Taung fossil using high-resolution computed tomography.

"A recent study has described the roughly 3 million-year-old fossil, thought to have belonged to a 3 to 4-year-old, as having a persistent metopic suture and open anterior fontanelle, two features that facilitate post-natal brain growth in human infants when their disappearance is delayed," said Carlson.

Comparisons with the existing hominin fossil record and chimpanzee variation do not support this evolutionary scenario.

Citing deficiencies in how the Taung fossil material has been recently assessed, the researchers suggest physical evidence does not incontrovertibly link features of the Taung skull, or its endocast, to early prefrontal lobe expansion, a brain region implicated in many human behaviors.

The authors also debate the previously offered theoretical basis for this adaptation in A. africanus. By refuting the presence of these features in the Taung Child, the researchers dispute whether these structures were selectively advantageous in hominin evolution, particularly in australopiths.

Thus, results of the new study show that there is still no evidence for this kind of skull adaptation that evolved before Homo, nor is there evidence for a link between such skull characteristics and the proposed accompanying early prefrontal lobe expansion, Carlson said.

Influenced by Self-Interest, Humans Less Concerned About Inequity To Others

Strongly influenced by their self-interest, humans do not protest being overcompensated, even when there are no consequences, researchers in Georgia State University’s Brains and Behavior Program have found.

This could imply that humans are less concerned than previously believed about the inequity of others, researchers said. Their findings are published in the journal Brain Connectivity. These findings suggest humans’ sense of unfairness is affected by their self-interest, indicating the interest humans show in others’ outcomes is a recently evolved propensity.

It has long been known that humans show sensitivity when they are at a disadvantage by refusing or protesting outcomes more often when they are offered less money than a social partner. But the research team of physics graduate students Bidhan Lamichhane and Bhim Adhikari and Brains and Behavior faculty Dr. Sarah Brosnan, associate professor of psychology, and Dr. Mukesh Dhamala, associate professor of physics and astronomy, reports that, contrary to expectations, humans do not show any sensitivity when they are overcompensated. They conclude that humans are more interested in their own outcomes than those of others.

“A true sense of fairness means that I get upset if I get paid more than you because I don’t think that’s fair,” Brosnan said. “We thought that people would protest quite a bit in the fixed decision game because it’s a cost-free way to say, ‘This isn’t fair.’ But that’s not what we saw at all. People protested higher offers at roughly the same rate that they refused offers where they got more, indicating that this lack of refusal in advantaged situations may not be because of the cost of refusing. It may just be because people don’t care as much as we thought they did if they’re getting more than someone else.”

The researchers also used functional magnetic resonance imaging (fMRI) to study the underlying brain mechanisms from 18 participants, who played three two-person economic exchange games that involved inequity in their favor and not in their favor. Overcompensated offers triggered a different brain circuit than undercompensated offers and indicate that people may be responding to overcompensation as if it were a reward. This could explain the lack of refusals in this unfair situation, researchers said.

Each game involved three offers for how $100 would be split: fair (amount between $40 to $60), unfair-low (disadvantageous to the subject, amount between $0 to $20) and unfair-overcompensated (advantageous to the subject, amount between $80 to $100). Participants played 30 rounds of each game and earned about two percent of the total amount from the games.

In the first two games, the subject received an offer for how much money they would receive and were then asked whether they wanted to reject or accept it. In the Ultimatum Game, if the responder rejected the offer, neither player received any money, leading to a fair outcome. In the Impunity Game, if the subject rejected the offer, only he or she lost the payoff, meaning the outcome was even more unfair than the offer. The subject got nothing, but the partner still got their proposed amount. In the Fixed Decision Game, the subject could choose to protest or not protest the offers, but this didn’t change the outcome for either player. This allowed subjects to protest offers without an associated cost.

The blood-oxygen level dependent signals of the brain were recorded by an MRI scanner as participants played the games. The results of brain response provided new insights into the functional role of the dorsolateral prefrontal cortex and related networks of brain regions for advantageous inequity and protest.

A network of brain regions consisting of the left caudate, right cingulate and right thalamus had a higher level of activity for overcompensated offers than for fair offers. For protest, a different network, consisting of the right dorsolateral prefrontal cortex, left ventrolateral prefrontal cortex and left substantia nigra, came into play. The researchers also mapped out how the brain activity flow occurred within these networks during decision-making.

ADHD children make poor decisions due to less differentiated learning processes

Which shirt do we put on in the morning? Do we drive to work or take the train? From which takeaway joint do we want to buy lunch? We make hundreds of different decisions every day. Even if these often only have a minimal impact, it is extremely important for our long-term personal development to make decisions that are as optimal as possible. People with ADHD often find this difficult, however. They are known to make impulsive decisions, often choosing options which bring a prompt but smaller reward instead of making a choice that yields a greater reward later on down the line. Researchers from the University Clinics for Child and Adolescent Psychiatry, University of Zurich, now reveal that different decision-making processes are responsible for such suboptimal choices and that these take place in the middle of the frontal lobe.

Mathematical models help to understand the decision-making processes

In the study, the decision-making processes in 40 young people with and without ADHD were examined. Lying in a functional magnetic resonance imaging scanner to record the brain activity, the participants played a game where they had to learn which of two images carried more frequent rewards. In order to understand the impaired mechanisms of participants with ADHD better, learning algorithms which originally stemmed from the field of artificial intelligence were used to evaluate the data. These mathematical models help to understand the precise learning and decision-making mechanisms better. “We were able to demonstrate that young people with ADHD do not inherently have difficulties in learning new information; instead, they evidently use less differentiated learning patterns, which is presumably why sub-optimal decisions are often made”, says first author Tobias Hauser.

Multimodal imaging affords glimpses inside the brain

In order to study the brain processes that triggered these impairments, the authors used multimodal imaging methods, where the participants were examined using a combined measurement of functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) to record the electrical activity and the blood flow in the brain. It became apparent that participants with ADHD exhibit an altered functioning in the medial prefrontal cortex – a region in the middle of the frontal lobe. This part of the brain is heavily involved in decision-making processes, especially if you have to choose between several options, and in learning from errors. Although a change in activity in this region was already discovered in other contexts for ADHD, the Zurich researchers were now also able to pinpoint the precise moment of this impairment, which already occurred less than half a second after a feedback, i.e. at a very early stage.

Psychologist Tobias Hauser, who is now researching at the Wellcome Trust Centre for Neuroimaging, University College London, is convinced that the results fundamentally improve our understanding of the mechanisms of impaired decision-making behavior in people with ADHD. The next step will be to study the brain messenger substances. “If our findings are confirmed, they will provide key clues as to how we might be able to design therapeutic interventions in future,” explains Hauser.

Literature:

Tobias U. Hauser, Reto Iannaccone, Juliane Ball, Christoph Mathys, Daniel Brandeis, Susanne Walitza & Silvia Brem: Role of Medial Prefrontal Cortex in Impaired Decision Making in Juvenile Attention-Deficit/Hyperactivity Disorder, in: JAMA Psychiatry

Our connection to content

Using neuroscience tools, Innerscope Research explores the connections between consumers and media.

It’s often said that humans are wired to connect: The neural wiring that helps us read the emotions and actions of other people may be a foundation for human empathy.

But for the past eight years, MIT Media Lab spinout Innerscope Research has been using neuroscience technologies that gauge subconscious emotions by monitoring brain and body activity to show just how powerfully we also connect to media and marketing communications.

“We are wired to connect, but that connection system is not very discriminating. So while we connect with each other in powerful ways, we also connect with characters on screens and in books, and, we found, we also connect with brands, products, and services,” says Innerscope’s chief science officer, Carl Marci, a social neuroscientist and former Media Lab researcher.

With this core philosophy, Innerscope — co-founded at MIT by Marci and Brian Levine MBA ’05 — aims to offer market research that’s more advanced than traditional methods, such as surveys and focus groups, to help content-makers shape authentic relationships with their target consumers.

“There’s so much out there, it’s hard to make something people will notice or connect to,” Levine says. “In a way, we aim to be the good matchmaker between content and people.”

Read more

How we form habits and change existing ones

Much of our daily lives are taken up by habits that we’ve formed over our lifetime. An important characteristic of a habit is that it’s automatic— we don’t always recognize habits in our own behavior. Studies show that about 40 percent of people’s daily activities are performed each day in almost the same situations. Habits emerge through associative learning. “We find patterns of behavior that allow us to reach goals. We repeat what works, and when actions are repeated in a stable context, we form associations between cues and response,” Wendy Wood explains in her session at the American Psychological Association’s 122nd Annual Convention.

What are habits?

Wood calls attention to the neurology of habits, and how they have a recognizable neural signature. When you are learning a response you engage your associative basal ganglia, which involves the prefrontal cortex and supports working memory so you can make decisions. As you repeat the behavior in the same context, the information is reorganized in your brain. It shifts to the sensory motor loop that supports representations of cue response associations, and no longer retains information on the goal or outcome. This shift from goal directed to context cue response helps to explain why our habits are rigid behaviors.

There is a dual mind at play, Wood explains. When our intentional mind is engaged, we act in ways that meet an outcome we desire and typically we’re aware of our intentions. Intentions can change quickly because we can make conscious decisions about what we want to do in the future that may be different from the past. However, when the habitual mind is engaged, our habits function largely outside of awareness. We can’t easily articulate how we do our habits or why we do them, and they change slowly through repeated experience. “Our minds don’t always integrate in the best way possible. Even when you know the right answer, you can’t make yourself change the habitual behavior,” Wood says.

Participants in a study were asked to taste popcorn, and as expected, fresh popcorn was preferable to stale. But when participants were given popcorn in a movie theater, people who have a habit of eating popcorn at the movies ate just as much stale popcorn as participants in the fresh popcorn group. “The thoughtful intentional mind is easily derailed and people tend to fall back on habitual behaviors. Forty percent of the time we’re not thinking about what we’re doing,” Wood interjects. “Habits allow us to focus on other things…Willpower is a limited resource, and when it runs out you fall back on habits.”

How can we change our habits?

Public service announcements, educational programs, community workshops, and weight-loss programs are all geared toward improving your day-to-day habits. But are they really effective? These standard interventions are very successful at increasing motivation and desire. You will almost always leave feeling like you can change and that you want to change. The programs give you knowledge and goal-setting strategies for implementation, but these programs only address the intentional mind.

In a study on the “Take 5” program, 35 percent of people polled came away believing they should eat 5 fruits and vegetables a day. Looking at that result, it appears that the national program was effective at teaching people that it’s important to have 5 servings of fruits and vegetables every day. But the data changes when you ask what people are actually eating. Only 11 percent of people reported that they met this goal. The program changed people’s intentions, but it did not overrule habitual behavior.

According to Wood, there are three main principles to consider when effectively changing habitual behavior. First, you must derail existing habits and create a window of opportunity to act on new intentions. Someone who moves to a new city or changes jobs has the perfect scenario to disrupt old cues and create new habits. When the cues for existing habits are removed, it’s easier to form a new behavior. If you can’t alter your entire environment by switching cities— make small changes. For instance, if weight-loss or healthy eating is your goal, try moving unhealthy foods to a top shelf out of reach, or to the back of the freezer instead of in front.

The second principle is remembering that repetition is key. Studies have shown it can take anywhere from 15 days to 254 days to truly form a new habit. “There’s no easy formula for how long it takes,” Wood says. Lastly, there must be stable context cues available in order to trigger a new pattern. “It’s easier to maintain the behavior if it’s repeated in a specific context,” Wood emphasizes. Flossing after you brush your teeth allows the act of brushing to be the cue to remember to floss. Reversing the two behaviors is not as successful at creating a new flossing habit. Having an initial cue is a crucial component.

(Image caption: Brain image showing activity in the amygdala, the area of the brain involved with emotion. The amydgala was more active during the graphic scenarios only when the harm being described was intentional. Credit: Marois Lab / Vanderbilt)

Fault trumps gruesome evidence when it comes to meting out punishment

Issues of crime and punishment, vengeance and justice date back to the dawn of human history, but it is only in the last few years that scientists have begun exploring the basic nature of the complex neural processes in the brain that underlie these fundamental behaviors.

Now a new brain imaging study – published online Aug. 3 by the journal Nature Neuroscience – has identified the brain mechanisms that underlie our judgment of how severely a person who has harmed another should be punished. Specifically, the study determined how the area of the brain that determines whether such an act was intentional or unintentional trumps the emotional urge to punish the person, however gruesome the harm may be.

“A fundamental aspect of the human experience is the desire to punish harmful acts, even when the victim is a perfect stranger. Equally important, however, is our ability to put the brakes on this impulse when we realize the harm was done unintentionally,” said Rene Marois, the Vanderbilt University professor of psychology who headed the research team. “This study helps us begin to elucidate the neural circuitry that permits this type of regulation.”

The study

In the experiment, the brains of 30 volunteers (20 male, 10 female, average age 23 years) were imaged using functional MRI (fMRI) while they read a series of brief scenarios that described how the actions of a protagonist named John brought harm to either Steve or Mary. The scenarios depicted four different levels of harm: death, maiming, physical assault and property damage. In half of them, the harm was clearly identified as intentional and in half it was clearly identified as unintentional.

Two versions of each scenario were created: one with a factual description of the harm and the other with a graphic description. For example, in a mountain climbing scenario where John cuts Steve’s rope, the factual version states, “Steve falls 100 feet to the ground below. Steve experiences significant bodily harm from the fall and he dies from his injuries shortly after impact.” And the graphic version reads, “Steve plummets to the rocks below. Nearly every bone in his body is broken upon impact. Steve’s screams are muffled by thick, foamy blood flowing from his mouth as he bleeds to death.”

After reading each scenario the participants were asked to list how much punishment John deserved on a scale from zero (no punishment) to nine (most severe punishment the subject endorsed).

Analysis of the responses

When the responses were analyzed, the researchers found that the manner in which the harmful consequences of an action are described significantly influences the level of punishment that people consider appropriate: When the harm was described in a graphic or lurid fashion then people set the punishment level higher than when it was described matter-of-factly. However, this higher punishment level only applied when the participants considered the resulting harm to be intentional. When they considered it to be unintentional, the way it was described didn’t have any effect.

“What we’ve shown is that manipulations of gruesome language leads to harsher punishment, but only in cases where the harm was intentional. Language had no effect when the harm was caused unintentionally,” summarized Michael Treadway, a post-doctoral fellow at Harvard Medical School and lead author of the study.

According to the researchers, the fact that the mere presence of graphic language could cause participants to ratchet up the severity of the punishments suggests that photographs, video and other graphic materials sampled from a crime scene is likely to have an even stronger impact on an individual’s desire to punish.

“Although the underlying scientific basis of this effect wasn’t known until now, the legal system recognized it a long time ago and made provisions to counteract it,” said Treadway. “Judges are permitted to exclude relevant evidence from a trial if they decide that its probative value is substantially outweighed by its prejudicial nature.”

Underlying neuroanatomy

The fMRI scans revealed the areas of the brain that are involved in this complex process. They found that the amygdala, an almond-shaped set of neurons that plays a key role in processing emotions, responded most strongly to the graphic language condition. Like the punishment ratings themselves, however, this effect in the amygdala was only present when harm was done intentionally. Moreover, in this situation the researchers found that the amygdala showed stronger communication with the dorsolateral prefrontal cortex (dlPFC), an area that is critical for punishment decision-making. When the harm was done unintentionally, however, a different regulatory network – one involved in decoding the mental states of other people – became more active and appeared to suppress amygdala responses to the graphic language, thereby preventing the amygdala from affecting decision-making areas in dlPFC.

“This is basically a reassuring finding,” said Marois. “It indicates that, when the harm is not intended, we don’t simply shunt aside the emotional impulse to punish. Instead, it appears that the brain down-regulates the impulse so we don’t feel it as strongly. That is preferable because the urge to punish is less likely to resurface at a future date.”