medial prefrontal cortex

Why psychopathic brains overvalue immediate rewards

Joshua Buckholtz wants to change the way you think about psychopaths — and he’s willing to go to prison to do it.

An associate professor of psychology at Harvard, Buckholtz is the senior author of a study that relies on brain scans of nearly 50 prison inmates to help explain why psychopaths make poor decisions that often lead to violence or other anti-social behavior.

What they found, he said, is that psychopaths’ brains are wired in a way that leads them to overvalue immediate rewards and neglect the future consequences of potentially dangerous or immoral actions. The study is described in a July 5 paper in Neuron.

“For years, we have been focused on the idea that psychopaths are people who cannot generate emotion and that’s why they do all these terrible things,” Buckholtz said. “But what we care about with psychopaths is not the feelings they have or don’t have, it’s the choices they make. Psychopaths commit an astonishing amount of crime, and this crime is both devastating to victims and astronomically costly to society as a whole.”

“And even though psychopaths are often portrayed as cold-blooded, almost alien predators, we have been showing that their emotional deficits may not actually be the primary driver of these bad choices. Because it’s the choices of psychopaths that cause so much trouble, we’ve been trying to understand what goes on in their brains when they make decisions that involve trade-offs between the costs and benefits of action,” he continued. “In this most recent paper … we are able to look at brain-based measures of reward and value and the communication between different brain regions that are involved in decision-making.”

Obtaining the scans used in the study, however, was no easy feat — where most studies face an uphill battle in bringing subjects into the lab, Buckholtz’s challenge was in bringing the scanner to his subjects.

The solution came in form of a “mobile” scanner transported in a tractor-trailer. The scanner is typically used for cancer screenings in rural areas. After trucking the equipment to two medium-security prisons in Wisconsin, the team, which included collaborators at the University of Wisconsin, Madison, and the University of New Mexico, would spend days calibrating the scanner, and then work to scan as many volunteers as possible as quickly as possible.

“It was a huge undertaking,” he said. “Most MRI scanners, they’re not going anywhere, but in this case, we’re driving this inside a prison and then in very quick succession we have to assess and scan the inmates.”

The team ultimately scanned the brains of 49 inmates over two hours as they took part in a delayed gratification test that asked them to choose between two options: receive a smaller amount of money immediately, or a larger amount at a later time. The results of the tests were then fit to a model that allowed researchers not only to measure how impulsive each participant’s behavior was, but to identify brain regions that played a role in assessing the relative value of such choices.

What they found, Buckholtz said, was people who scored high for psychopathy showed greater activity in a region called the ventral striatum — known to be involved in evaluating the subjective reward — for the more immediate choice.

“So the more psychopathic a person is, the greater the magnitude of that striatal response,” Buckholtz said. “That suggests that the way they are calculating the value rewards is dysregulated — they may overrepresent the value of immediate reward.”

When Buckholtz and colleagues began mapping which brain regions were connected to the ventral striatum, it became clear why.

“We mapped the connections between the ventral striatum and other regions known to be involved in decision-making, specifically regions of the prefrontal cortex known to regulate striatal response,” he said. “When we did that, we found that connections between the striatum and the ventral medial prefrontal cortex were much weaker in people with psychopathy.

That lack of connection is important, Buckholtz said, because this portion of the prefrontal cortex is thought to be important for “mental time-travel” — envisioning the future consequences of actions. There is increasing evidence that the prefrontal cortex uses the outcome of this process to change how strongly the striatum responds to rewards. With that prefrontal modulating influence weakened, the value of the more immediate choice may become dramatically overrepresented.

“The striatum assigns values to different actions without much temporal context,” he said. “We need the prefrontal cortex to make prospective judgements how an action will affect us in the future — ‘If I do this, then this bad thing will happen.’ The way we think of it is if you break that connection in anyone, they’re going to start making bad choices because they won’t have the information that would otherwise guide their decision-making to more adaptive ends.”

The effect was so pronounced, Buckholtz said, that researchers were able to use the degree of connection between the striatum and the prefrontal cortex to accurately predict how many times inmates had been convicted of crimes.

Ultimately, Buckholtz said, his goal is to erase the popular image of psychopaths as incomprehensible, cold-blooded monsters and see them for what they are — human beings whose brains are simply wired differently.

“They’re not aliens, they’re people who make bad decisions,” he said. “The same kind of short-sighted, impulsive decision-making that we see in psychopathic individuals has also been noted in compulsive overeaters and substance abusers. If we can put this back into the domain of rigorous scientific analysis, we can see psychopaths aren’t inhuman, they’re exactly what you would expect from humans who have this particular kind of brain wiring dysfunction.”

Structure/function: The Parietal Lobe

Behold! Your parietal lobe! You can thank this lobe for your ability to slap yourself in the face! You’re welcome!

Because it allows you to know where in space your hand is, where in space your face is, and where they are in relation to each other. Congratulations! If you have parietal lobe issues, you might have issues slapping yourself in the face… among other issues but those are probably not relevant.

More specifically, the parietal lobe is split up into the above sections. First you have the somatosensory cortex

(This post was brought to you by me, figuring out how to “remove background” on an image and abusing this newfound power). So with the hand slapping thing, you will feel both your hand making contact with your face, and your face being slapped, thanks to this doohickey!

The superior and supramarginal cortices are visual, so it guides your movement to, say, pick up a water bottle. And slap yourself in the face, although you can do that with your eyes closed (go ahead, try it). That’s thanks to the posterior cingulate gyrus but we will get there later because it is a LOT. For now we have the friendly, simple

Angular Gyrus, which does what it says. So thinking about your place in space, where you want to go, where you’ve been, which way is north, which way is your house. Boom. Angular Gyrus. The Angular Gyrus and the Supramarginal Gyrus together make up the inferior parietal lobule (sub-lobe)

Now on the OTHER side of the parietal cortex (cut your brain in half, saggitally, to expose this part) (don’t cut, like, YOUR brain in half… couldn’t learn much then, could you) (actually) (we won’t go there). Episodic memory retrieval=who, what, when, where, and emotions of memories.Makes sense this is with visuo-spatial imagery. When you imagine up these memories, you envision the location of these memories and where these memories took place. Self-consciousness is also related to this area (but not exclusively located here. It’s pretty well understood that’s not located in one area but processed throughout the brain. NOW for the REAL doosy

Phew. Look at that. And such a small area. It is primarily known for its role in the Dorsal Stream in visual processing. A lot of its other roles kind of relate to this, as it is also known as the “where” stream. So spacial awareness, movements in space, mental rotation (that skill on IQ tests where they give you the shape and ask you to ID the shape from another angle), mental imagery, manipulation of visual imagery. So your understanding and manipulation of space. Interestingly (possibly connected) math and reading abilities are also highly related to this area. Spatial and non-spatial working memory (temporary memory holding, decision making), response inhibition, and task switching are all related to this area. Which is interesting because they are also all related to the medial prefrontal cortex. Pathway?? (Probably, I haven’t looked into it)

Not labeled here:

Medial Parietal-Pain processing and meditation

Intraparietal Sulcus-Saccadic eye movements, attention, reaching, grasping, tactile manipulation of objects, observing hand movements, passive tool use, object matching and object size and orientation discrimination. (aka REALLY relevant for slapping yourself)

So there you have it. The overall structures and their functions within the parietal lobe! 

2

Oh my god. Ohhhhh my god oh my god oh my. god.

Nothing conclusive or anything but these are neurons from brains of rats that I cared for and collected data on and collected the samples on and stained for weeks (the staining alone took more time than the data collection) and these are MY neurons.

Technically they’re my post-doc’s neurons

technically they’re the rat’s neurons. 

But they are just so beautiful and perfect and real. They’re actual pyramidal neurons in the medial prefrontal cortex with a soma and dendrites and everything.

The Neurological Pleasures of Fast Fashion

The Atlantic has an article today on the neurological pleasures of fast fashion. Not much new revealed here, except for the science behind what we already know – people like buying things and getting deals, and the culture of fast fashion has encouraged people to buy things they don’t really need. An excerpt: 

The researchers then showed the subject the item’s price. The medial prefrontal cortex weighed the decision, as the insula, which processes pain, reacted to the cost. Deciding whether to buy put the brain, as the study put it, in a “hedonic competition between the immediate pleasure of acquisition and an equally immediate pain of paying.” The mindset is in line with evidence that shows happiness in shopping comes from the pursuit of goods—from the sensation of wanting something.

While pleasure kicks in just from the act of looking, there’s also pleasure in purchasing, or more specifically, in getting a bargain. The medial prefrontal cortex is the part of the brain that does what’s essentially cost-benefit analysis. “It seemed to be responsive not necessarily to price alone, or how much I like it, but that comparison of the two: how much I like it compared to what you charge me for it,” says Scott Rick, one of the study’s authors, now an assistant professor of marketing at the University of Michigan.

Fast fashion perfectly feeds this neurological process. First, the clothing is incredibly cheap, which makes it easy to buy. Second, new deliveries to stores are frequent, which means customers always have something new to look at and desire. Zara stores famously gets two new shipments of clothes each week, while H&M and Forever21 get clothes daily. These brands are notorious for knocking off high-end designers, allowing the customer to get something at least superficially similar to the original at a small fraction of the cost, and they’re priced lower than the rest of the market, making their products feel like a bargain.

[…] 

The consumption isn’t by any means limited to the U.S. Women in Britain, for instance, now own four times as much clothing as they did in 1980. This glut of clothing is having effects beyond stuffing our closets. About 10.5 million tons of clothes end up in American landfills each year, and secondhand stores receive so much excess clothing that they only resell about 20 percent of it. The remainder is sent to textile recyclers, where it’s either turned into rags or fibers, or, if the quality is high enough, it’s exported and cycled through a cut throat, global, used-clothing business.

You can read the rest here.

Old memories recombine to give a taste of the unknown

Ever tried beetroot custard? Probably not, but your brain can imagine how it might taste by reactivating old memories in a new pattern.

Helen Barron and her colleagues at University College London and Oxford University wondered if our brains combine existing memories to help us decide whether to try something new.

So the team used an fMRI scanner to look at the brains of 19 volunteers who were asked to remember specific foods they had tried.

Each volunteer was then given a menu of 13 unusual food combinations – including beetroot custard, tea jelly, and coffee yoghurt – and asked to imagine how good or bad they would taste, and whether or not they would eat them.

“Tea jelly was popular,” says Barron. “Beetroot custard not so much.”

When each volunteer imagined a new combination, they showed brain activity associated with each of the known ingredients at the same time. It is the first evidence to suggest that we use memory combination to make decisions, says Barron.

Rat Brains Point to Lead's Role in Schizophrenia

A study of the brains of rats exposed to lead has uncovered striking similarities with what is known about the brains of human schizophrenia patients, adding compelling evidence that lead is a factor in the onset of schizophrenia.

Results of the study by scientists at Columbia University’s Mailman School of Public Health appear in the journal Translational Psychiatry.

The researchers found that lead had a detrimental effect on cells in three brain areas implicated in schizophrenia: the medial prefrontal cortex, the hippocampus, and the striatum of rats exposed to lead before birth and in the early part of their lives. Density of brain cells known as Parvalbumin-Positive GABAergic interneurons, or PVGI, declined by approximately a third—at roughly the same percentage decline seen in schizophrenia patients. They also identified higher levels of a dopamine receptor called D2R. Again, the magnitude of the increase matched what has been documented in human schizophrenia patients, and in a previous study of genetically engineered mice.

“The similarities in the brain structure and neuronal systems between what we see in lead-exposed rats and human schizophrenia patients are striking, and adds to a growing body of literature suggesting that early lead exposure primes the brain for schizophrenia later in life,” says senior author Tomás Guilarte, PhD, chair of Environmental Health Sciences at the Mailman School.

(Image caption: Brains of rats exposed to lead (right) had a lower cell density of parvalbumin-positive neurons compared with controls (left))

Cocaine Insights

In a related finding, the researchers found that rats exposed to lead had a much stronger reaction to cocaine than healthy rat controls. In the experiment, lead-exposed rats that were injected with cocaine ran around in their cages at twice the distance of lead-free control rats. The rat behavior is meaningful because it mirrors what is seen in schizophrenia patients, who are known to have a heightened response to the drug.

Schizophrenia is not the only possible consequence of lead exposure. A follow-up experiment will allow the rats to self-administer cocaine in order to test whether lead exposure plays a role in addiction.

“We are currently assessing the impact of lead exposure on both the rewarding and reinforcing properties of addictive drugs like cocaine while exploring the biological underpinnings of how lead exposure plays a role in addiction,” says first author Kirstie Stansfield, PhD, associate research scientist at the Mailman School.