Tag Archives: #reward

Mirror, Mirror…Viewing Your Own Face, Even Subconsciously, is Rewarding (Neuroscience)

Researchers from Osaka University find that subconscious viewing of your own face can activate reward pathways

As humans, we each have a powerful ability to easily recognize our own face. But now, researchers from Japan have uncovered new information about how our cognitive systems enable us to distinguish our own face from those of others, even when the information is presented subliminally.

In a study published this month in Cerebral Cortex, researchers from Osaka University have revealed that a central element of the dopamine reward pathway in the brain was activated when participants were subliminally shown images of their face. This provides new clues regarding the underlying processes of the brain involved in self-facial recognition.

When we are exposed to a subliminal image of our face–meaning we are not fully aware of it–many brain regions are activated in addition to those that process face information. Furthermore, our brain responds differently to supraliminal (conscious) and subliminal (subconscious) images of our face compared to faces of others. However, whether we use the same or different neural networks to process subliminal versus supraliminal faces has not been established, something the researchers at Osaka University aimed to address with this research.

“We are better at recognizing our own face compared to faces of others, even when the information is delivered subliminally,” says lead author of the study Chisa Ota. “However, little is known about whether this advantage involves the same brain or different areas that are activated by supraliminal presentation of our face.”

To address this, the researchers used functional magnetic resonance imaging (fMRI) to examine the differences between brain activity elicited by subliminally presented images of the faces of participants and faces of others. They also examined brain activation produced by subliminally presented images of faces with modified features.

“The results provided us with new insights regarding the neural mechanisms of the self-face advantage,” explains Tamami Nakano, senior author. “We found that activation in the ventral tegmental area, which is a central component of the dopamine reward pathway, was stronger for subliminal presentations of the participant’s face compared with faces of others.”

Instead, subliminal presentation of the faces of others induced activation in the amygdala of the brain, which is known to respond to unfamiliar information. This difference in brain responses to the face of the participant or those of others was consistent even when the faces were modified, as long as the shapes of the facial features were retained.

“Our findings indicate that the dopamine reward pathway is involved in enhanced processing of one’s own face even when the information is subliminal”, says Tamami Nakano. “Furthermore, discrimination of one’s own face from those of others appear to rely on the information of facial parts.”

These findings advance the understanding of the neural mechanisms of subliminal self-facial processing. Given that the dopamine reward pathway is automatically involved in unconscious self-facial processing, this research may have applications in efforts to unconsciously manipulate motivation.

The article, “Self-face activates the dopamine reward pathway without awareness” was published in Cerebral Cortex at DOI: https://doi.org/10.1093/cercor/bhab096

Featured image: Subliminal presentation of face (upper) and brain regions showing self-face related activation (bottom). © Osaka University


Provided by Osaka University

Why Opioids Cannot Fix Chronic Pain? (Medicine)

Researchers say that emotional pain and chronic pain are related, and painkillers, ultimately, make things worse.

A broken heart is often harder to heal than a broken leg. Now researchers say that a broken heart can contribute to lasting chronic pain.

Pain experts at UW Medicine say emotional pain activates many of the same limbic brain centers as physical pain. © Gettyimages

In a reflections column published Dec. 21 in the Annals of Family Medicine, pain experts Mark Sullivan and Jane Ballantyne at the University of Washington School of Medicine, say emotional pain and chronic physical pain are bidirectional. Painkillers, they said, ultimately make things worse.

Their argument is based on new epidemiological and neuroscientific evidence, which suggests emotional pain activates many of the same limbic brain centers as physical pain. This is especially true, they said, for the most common chronic pain syndromes – back pain, headaches, and fibromyalgia.

Opioids may make patients feel better early on, but over the long term these drugs cause all kinds of havoc on their well-being, the researchers said.

“Their social and emotional functioning is messed up under a wet blanket of opioids,” Sullivan said.

The researchers said new evidence suggests that the body’s reward system may be more important than tissue damage in the transition from acute to chronic pain.

By reward system, they are referring, in part, to the endogenous opioid system, a complicated system connected to several areas of the brain, The system includes the natural release of endorphins from pleasurable activities.

When this reward system is damaged by manufactured opioids, it perpetuates isolation and chronic illness and is a strong risk factor for depression, they said.

“Rather than helping the pain for which the opioid was originally sought, persistent opioid use may be chasing the pain in a circular manner, diminishing natural rewards from normal sources of pleasure, and increasing social isolation,“ they wrote.

Both Sullivan and Ballantyne prescribe opioids for their patients and say they have a role in short-term use.

“Long-term opioid therapy that lasts months and perhaps years should be a rare occurrence because it does not treat chronic pain well, it impairs human social and emotional function, and can lead to opioid dependence or addiction,” they wrote.

What Sullivan recommends is if patients are on high-dose long-term opioids and they are not having clear improvement in pain and function, they need to taper down or switch to buprenorphine. If available, a multidisciplinary pain program using a case manager to monitor their care and well-being, similar to those for diabetes and depression care, may be of benefit.

Reference: Mark D. Sullivan and Jane C. Ballantyne, “When Physical and Social Pain Coexist: Insights Into Opioid Therapy”, The Annals of Family Medicine December 2020, https://www.annfammed.org/content/early/2020/12/15/afm.2591 DOI: https://doi.org/10.1370/afm.2591

Provided by University of Washington Health and Medical Sciences

Scientists Reveal Regions of The Brain Where Serotonin Promotes Patience (Neuroscience)

Serotonin keeps mice waiting longer for food, depending on where in the brain it’s released.

We’ve all been there. Whether we’re stuck in traffic at the end of a long day, or eagerly anticipating the release of a new book, film or album, there are times when we need to be patient. Learning to suppress the impulse for instant gratification is often vital for future success, but how patience is regulated in the brain remains poorly understood.

Serotonin-releasing neurons (green arrows) from the dorsal raphe nucleus (DRN) penetrate many other areas of the brain, including the nucleus accumbens (NAc), orbitofrontal cortex (OFC) and medial prefrontal cortex (mPFC). ©OIST

Now, in a study on mice conducted by the Neural Computation Unit at the Okinawa Institute of Science and Technology Graduate University (OIST), the authors, Dr. Katsuhiko Miyazaki and Dr. Kayoko Miyazaki, pinpoint specific areas of the brain that individually promote patience through the action of serotonin. Their findings were published 27th November in Science Advances.

“Serotonin is one of the most famous neuromodulators of behavior, helping to regulate mood, sleep-wake cycles and appetite,” said Dr. Katsuhiko Miyazaki. “Our research shows that release of this chemical messenger also plays a crucial role in promoting patience, increasing the time that mice are willing to wait for a food reward.”

Their most recent work draws heavily on previous research, where the unit used a powerful technique called optogenetics – using light to stimulate specific neurons in the brain – to establish a causal link between serotonin and patience.

The scientists bred genetically engineered mice which had serotonin-releasing neurons that expressed a light-sensitive protein. This meant that the researchers could stimulate these neurons to release serotonin at precise times by shining light, using an optical fiber implanted in the brain.

The researchers found that stimulating these neurons while the mice were waiting for food increased their waiting time, with the maximum effect seen when the probability of receiving a reward was high but when the timing of the reward was uncertain.

“In other words, for the serotonin to promote patience, the mice had to be confident that a reward would come but uncertain about when it would arrive,” said Dr. Miyazaki.

In the previous study, the scientists focused on an area of the brain called the dorsal raphe nucleus – the central hub of serotonin-releasing neurons. Neurons from the dorsal raphe nucleus reach out into other areas of the forebrain and in their most recent study, the scientists explored specifically which of these other brain areas contributed to regulating patience.

The team focused on three brain areas that had been shown to increase impulsive behaviors when they were damaged – a deep brain structure called the nucleus accumbens, and two parts of the frontal lobe called the orbitofrontal cortex and the medial prefrontal cortex.

“Impulse behaviors are intrinsically linked to patience – the more impulsive an individual is, the less patient – so these brain areas were prime candidates,” explained Dr. Miyazaki.

Good things come to those who wait (or not…)

In the study, the scientists implanted optical fibers into the dorsal raphe nucleus and also one of either the nucleus accumbens, the orbitofrontal cortex, or the medial prefrontal cortex.

The researchers trained mice to perform a waiting task where the mice held with their nose inside a hole, called a “nose poke”, until a food pellet was delivered. The scientists rewarded the mice in 75% of trials. In some test conditions, the timing of the reward was fixed at six or ten seconds after the mice started the nose poke and in other test conditions, the timing of the reward varied.

In the remaining 25% of trials, called the omission trials, the scientists did not provide a food reward to the mice. They measured how long the mice continued performing the nose poke during omission trials – in other words, how patient they were – when serotonin-releasing neurons were and were not stimulated.

When the researchers stimulated serotonin-releasing neural fibers that reached into the nucleus accumbens, they found no increase in waiting time, suggesting that serotonin in this area of the brain has no role in regulating patience.

The scientists studied the effect of stimulating serotonin-releasing neurons (black arrows) in the medial prefrontal cortex (mPFC), the orbitofrontal cortex (OFC) and nucleus accumbens (NAc) on waiting time, under variable time trials (e.g. food delivered after 2,6 or 10 seconds) and under fixed time trials (e.g. food delivered after 6 seconds). No effect was seen when neurons in the NAc were stimulated. A weak effect led to a small increase in waiting time when neurons in the mPFC were stimulated in variable time trials. A strong effect was seen when neurons in the OFC were stimulated in variable time trials and a weak effect was seen in fixed time trials. The thickness of the dashed arrows indicate the strength of the effect. © OIST

But when the scientists stimulated serotonin release in the orbitofrontal cortex and the medial prefrontal cortex while the mice were holding the nose poke, they found the mice waited longer, with a few crucial differences.

In the orbitofrontal cortex, release of serotonin promoted patience as effectively as serotonin activation in the dorsal raphe nucleus; both when reward timing was fixed and when reward timing was uncertain, with stronger effects in the latter.

But in the medial prefrontal cortex, the scientists only saw an increase in patience when the timing of the reward was varied, with no effect observed when the timing was fixed.

“The differences seen in how each area of the brain responded to serotonin suggests that each brain area contributes to the overall waiting behavior of the mice in separate ways,” said Dr. Miyazaki.

Modelling patience

To investigate this further, the scientists constructed a computational model to explain the waiting behavior of the mice.

The model assumes that the mice have an internal model of the timing of reward delivery and keep estimating the probability that a reward will be delivered. They can therefore judge over time whether they are in a reward or non-reward trial and decide whether or not to keep waiting. The model also assumes that the orbitofrontal cortex and the medial prefrontal cortex use different internal models of reward timing, with the latter being more sensitive to variations in timing, to calculate reward probabilities individually.

The researchers found that the model best fitted the experimental data of waiting time by increasing the expected reward probability from 75% to 94% under serotonin stimulation. Put more simply, serotonin increased the mice’s belief that they were in a reward trial, and so they waited longer.

Importantly, the model showed that stimulation of the dorsal raphe nucleus increased the probability from 75% to 94% in both the orbital frontal cortex and the medial prefrontal cortex, whereas stimulation of the brain areas separately only increased the probability in that particular area.

“This confirmed the idea that these two brain areas are calculating the probability of a reward independently from each other, and that these independent calculations are then combined to ultimately determine how long the mice will wait,” explained Dr. Miyazaki. “This sort of complementary system allows animals to behave more flexibly to changing environments.”

Ultimately, increasing our knowledge of how different areas of the brain are more or less affected by serotonin could have vital implications in future development of drugs. For example, selective serotonin reuptake inhibitors (SSRIs) are drugs that boost levels of serotonin in the brain and are used to treat depression.

“This is an area we are keen to explore in the future, by using depression models of mice,” said Dr. Miyazaki. “We may find under certain genetic or environmental conditions that some of these identified brain areas have altered functions. By pinning down these regions, this could open avenues to provide more targeted treatments that act on specific areas of the brain, rather than the whole brain.”

References: Katsuhiko Miyazaki, Kayoko W. Miyazaki, Gaston Sivori, Akihiro Yamanaka, Kenji F. Tanaka, Kenji Doya, “Serotonergic projections to the orbitofrontal and medial prefrontal cortices differentially modulate waiting for future rewards”, Science Advances 27 Nov 2020: Vol. 6, no. 48, eabc7246 DOI: 10.1126/sciadv.abc7246

Provided by OIST

Scientists Identify Brain cells That Help Drive Bodily Reaction to Fear, Anxiety (Neuroscience)

A feat of basic neuroscience co-led by UNC School of Medicine scientists, the discovery of a set of arousal-related neurons could help scientists develop better treatments for anxiety disorders, psychiatric illnesses.

Strong emotions such as fear and anxiety tend to be accompanied and reinforced by measurable bodily changes including increased blood pressure, heart rate and respiration, and dilation of the eyes’ pupils. These so-called “physiological arousal responses” are often abnormally high or low in psychiatric illnesses such as anxiety disorders and depression. Now scientists at the UNC School of Medicine have identified a population of brain cells whose activity appears to drive such arousal responses.

Pnoc neurons in the BNST shown in green. ©Hiroshi Nomura, PhD

The scientists, whose study is published in Cell Reports, found that artificially forcing the activity of these brain cells in mice produced an arousal response in the form of dilated pupils and faster heart rate, and worsened anxiety-like behaviors.

The finding helps illuminate the neural roots of emotions, and point to the possibility that the human-brain counterpart of the newly identified population of arousal-related neurons might be a target of future treatments for anxiety disorders and other illnesses involving abnormal arousal responses.

“Focusing on arousal responses might offer a new way to intervene in psychiatric disorders,” said first author Jose Rodríguez-Romaguera, PhD, assistant professor in the UNC Department of Psychiatry and member of the UNC Neuroscience Center, and co-director of the Carolina Stress Initiative at the UNC School of Medicine.

Rodríguez-Romaguera and co-first author Randall Ung, PhD, an MD-PhD student and adjunct assistant professor in the Department of Psychiatry, led this study when they were members of the UNC laboratory of Garret Stuber, PhD, who is now at the University of Washington.

“This work not only identifies a new population of neurons implicated in arousal and anxiety, but also opens the door for future experiments to systematically examine how molecularly defined cell types contribute to complex emotional and physiological states,” Stuber said. “This will be critical going forward for developing new treatments for neuropsychiatric disorders.”

Anxiety disorders, depression, and other disorders featuring abnormally high or low arousal responses affect a large fraction of the human population, including tens of millions of adults in the United States alone. Treatments may alleviate symptoms, but many have adverse side effects, and the root causes of these disorders generally remain obscure.

Untangling these roots amid the complexity of the brain has been an enormous challenge, one that laboratory technology has only recently begun to surmount.

Rodríguez-Romaguera, Ung, Stuber and colleagues examined a brain region within the amygdala called the BNST (bed nucleus of the stria terminalis), which has been linked in prior research to fear and anxiety-like behaviors in mice.

Increasingly, scientists view this region as a promising target for future psychiatric drugs. In this case, the researchers zeroed in on a set of BNST neurons that express a neurotransmitter gene, Pnoc, known to be linked to pain sensitivity and more recently to motivation.

The team used a relatively new technique called two-photon microscopy to directly image BNST Pnoc neurons in the brains of mice while the mice were presented with noxious or appealing odors – stimuli that reliably induce fear/anxiety and reward behaviors, respectively, along with the appropriate arousal responses. In this way, the scientists found that activity in these neurons tended to be accompanied by the rapid dilation of the pupils of the mice when the animals were presented with either of these odor stimuli.

The researchers then used another advanced technique called optogenetics – using light to control genetically engineered cells – to artificially drive the activity of the BNST Pnoc neurons. They found that spurring on BNST Pnoc activity triggered a pupillary response, as well as increased heart rate. Optogenetically driving the neurons while the mice underwent an anxiety-inducing maze test (traditionally used to assess anxiety drugs) increased the animals’ signs of anxiety, while optogenetically quieting the neurons had the opposite effect.

“Essentially we found that activating these BNST Pnoc neurons drives arousal responses and worsens anxiety-like states,” Rodríguez-Romaguera said.

The discovery is mainly a feat of basic neuroscience. But it also suggests that targeting arousal-driving neurons such as BNST Pnoc neurons with future drugs might be a good way to reduce abnormally strong responses to negative stimuli in anxiety disorders, for example, and to boost abnormally weak responses to positive stimuli in depression.

The study uncovered evidence that BNST Pnoc neurons are not all the same but differ in their responses to positive or negative stimuli, and the researchers are now cataloguing these BNST Pnoc neuron sub-groups.

“Even this small part of the amygdala is a complex system with different types of neurons,” Ung said. Teasing this apart will help us understand better how this system works.”

References: https://www.cell.com/cell-reports/fulltext/S2211-1247(20)31351-6?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS2211124720313516%3Fshowall%3Dtrue

Provided by University of North Calorina Health Care

New Insight Into How Brain Neurons Influence Choices (Neuroscience)

When you are faced with a choice — say, whether to have ice cream or chocolate cake for dessert — sets of brain cells just above your eyes fire as you weigh your options. Animal studies have shown that each option activates a distinct set of neurons in the brain. The more enticing the offer, the faster the corresponding neurons fire.

By studying animals choosing between two drink options, researchers at Washington University School of Medicine in St. Louis have discovered that the activity of certain neurons in the brain leads directly to the choice of one option over another. The findings could lead to better understanding of how decision-making goes wrong in conditions such as addiction and depression. ©Mike Worful.

Now, a study in monkeys by researchers at Washington University School of Medicine in St. Louis has shown that the activity of these neurons encodes the value of the options and determines the final decision. In the experiments, researchers let animals choose between different juice flavors. By changing the neurons’ activity, the researchers changed how appealing the monkeys found each option, leading the animals to make different choices. The study is published Nov. 2 in the journal Nature.

A detailed understanding of how options are valued and choices are made in the brain will help us understand how decision-making goes wrong in people with conditions such as addiction, eating disorders, depression and schizophrenia.

“In a number of mental and neuropsychiatric disorders, patients consistently make poor choices, but we don’t understand exactly why,” said senior author Camillo Padoa-Schioppa, PhD, a professor of neuroscience, of economics and of biomedical engineering. “Now we have located one critical piece of this puzzle. As we shed light on the neural mechanisms underlying choices, we’ll gain a deeper understanding of these disorders.”

In the 18th century, economists Daniel Bernoulli, Adam Smith and Jeremy Bentham suggested that people choose among options by computing the subjective value of each offer, taking into consideration factors such as quantity, quality, cost and the probability of actually receiving the promised offer. Once computed, values would be compared to make a decision. It took nearly three centuries to find the first concrete evidence of such calculations and comparisons in the brain. In 2006, Padoa-Schioppa and John Assad, PhD, a professor of neurobiology at Harvard Medical School, published a groundbreaking paper in Nature describing the discovery of neurons that encode the subjective value offered and chosen goods. The neurons were found in the orbitofrontal cortex, an area of the brain just above the eyes involved in goal-directed behavior.

At the time, though, they were unable to demonstrate that the values encoded in the brain led directly to choosing one option over another.

“We found neurons encoding subjective values, but value signals can guide all sorts of behaviors, not just choice,” Padoa-Schioppa said. “They can guide learning, emotion, perceptual attention, and aspects of motor control. We needed to show that value signals in a particular brain region guide choices.”

To examine the connection between values encoded by neurons and choice behavior, researchers performed two experiments. The study was conducted by first authors Sébastien Ballesta, PhD, then a postdoctoral researcher, and Weikang Shi, a graduate student, with the help of Katherine Conen, PhD, then a graduate student, who designed one of the experiments. Ballesta is now an associate professor at the University of Strasbourg in Strasbourg, France; Conen is now at Brown University.

In one experiment, the researchers repeatedly presented monkeys with two drinks and recorded the animals’ selections. The drinks were offered in varying amounts and included lemonade, grape juice, cherry juice, peach juice, fruit punch, apple juice, cranberry juice, peppermint tea, kiwi punch, watermelon juice and salted water. The monkeys often preferred one flavor over another, but they also liked to get more rather than less, so their decisions were not always easy. Each monkey indicated its choice by glancing toward it, and the chosen drink was delivered.

Then, the researchers placed tiny electrodes in each monkey’s orbitofrontal cortex. The electrodes painlessly stimulate the neurons that represent the value of each option. When the researchers delivered a low current through the electrodes while a monkey was offered two drinks, neurons dedicated to both options began to fire faster. From the perspective of the monkey, this meant that both options became more appealing but, because of the way values are encoded in the brain, the appeal of one option increased more than that of the other. The upshot is that low-level stimulation made the animal more likely to choose one particular option, in a predictable way.

In another experiment, the monkeys saw first one option, then the other, before they made a choice. Delivering a higher current while the monkey was considering one option disrupted the computation of value taking place at that time, making the monkey more likely to choose whichever option was not disrupted. This result indicates that values computed in the orbitofrontal cortex are a necessary part of making a choice.

“When it comes to this kind of choices, the monkey brain and the human brain appear very similar,” Padoa-Schioppa said. “We think that this same neural circuit underlies all sorts of choices people make, such as between different dishes on a restaurant menu, financial investments, or candidates in an election. Even major life decisions like which career to choose or whom to marry probably utilize this circuit. Every time a choice is based on subjective preferences, this neural circuit is responsible for it.”

References: Ballesta, S., Shi, W., Conen, K.E. et al. Values encoded in orbitofrontal cortex are causally related to economic choices. Nature (2020). https://doi.org/10.1038/s41586-020-2880-x link: https://www.nature.com/articles/s41586-020-2880-x

Provided by Washington University School Of Medicine

The Cobra Effect: No Loophole Goes Unexploited (Psychology)

The Cobra Effect describes the unintended consequences and perverse outcomes that can occur when organizations or governments offer rewards, bounties, or incentives to encourage people to take some specific, pro-social action. Such programs can sometimes tempt unscrupulous individuals to find and exploit flaws or weaknesses that will allow them to claim the reward through fraud or deceit. When the program is overrun by such corruption, it collapses into failure, sometimes leaving matters worse than before any incentives were offered.

Economist Horst Siebert coined the term “cobra effect” based on the following: When the British ruled India, the city of Delhi was infested with cobras. To enlist the public’s help in eradicating the snakes, officials offered a bounty on cobra skins. Soon, however, a cottage industry of cobra farming sprang up. People were breeding them for their skins. The British paid out more and more money, but the cobra infestation did not abate. And cobra farming only added to the problem. When authorities finally got wise to the scam and withdrew the bounty, the farmers set their now-worthless cobras free. In this case, truly the road to hell was paved with good intention – and cobra skins.

A current example

This week Brigham Young University issued the following warning: “Students who…have intentionally exposed themselves or others to [Covid-19] will be immediately suspended from the university and may be permanently dismissed.” BYU apparently received credible information that some students were trying to become infected in order to score a bigger paycheck when donating plasma.

Healthy individuals are paid $50 per visit by a plasma donation center near the BYU campus. However, the same donation center offers $100 per visit for those with Covid-19 “convalescent plasma.” Like entrepreneurs seeking to capitalize on a niche market, some students may have seen Covid-19 as an opportunity to apply what they learned in Economics 101 about supply and demand.

Other examples

In 2008 the police in Oakland, California conducted a gun buy-back program. Presumably, the goal was to reduce criminals’ easy access to firearms. Anyone could turn in a firearm and walk away with $250, no questions asked.

A newspaper account called the buy-back program “a poorly organized fiasco.” (This raises the question: What distinguishes a poorly organized fiasco from a fiasco that has been well-organized? I assume that an incompetent fiasco would be worthy of contempt, whereas a skillfully managed fiasco would merit grudging respect. But that is an ontological question beyond the scope of this post.) What could have gone so wrong with the buy-back? Let us count the ways:

• “The first two people in line at one of the three buyback locations were gun dealers with 60 firearms packed in the trunk of their cars.”
• They “bought a dozen guns from seniors living in an assisted-living facility.”
• Rather than getting guns off the streets, some less-than-trustworthy individuals were turning in their cheap weapons and using the $250 bounty to buy a better gun.
• So many people rushed to turn in guns that the police department ran out of money and had to give IOUs, leaving the department with a $170,000 debt.

With the recent Paycheck Protection Program, Congress set up a program whose flawed execution allowed grifters to obtain millions of dollars to meet payroll expenses, when there were few if any employees and scarcely any payroll to meet.

Anticipating and avoiding perverse outcomes and unintended consequences requires the ability to apply second-order thinking skills to planning and problem-solving. First-order thinking is linear and simplistic: How do we get rid of the cobras? Let’s offer a bounty to people for killing them. Second-order thinking is

• Analytical. The who, what, when, where, why, and how of the project, its planning, and its execution.
• Critical. What are our assumptions, what could go wrong, how could external influences affect our plans and the outcome, and on what evidence are we confident in our plans and assumptions?
• Skeptical. What can go wrong and how, what is the probability of that happening, and what unintended consequences or perverse outcomes might ensue?

This article is republished here from Psychology Today Under Common Creative licences.

Nerve Cell Activity Shows How Confident We Are (Neuroscience)

Should I or shouldn’t I? The activity of individual nerve cells in the brain tells us how confident we are in our decisions. This is shown by a recent study by researchers at the University of Bonn. The result is unexpected – the researchers were actually on the trail of a completely different evaluation mechanism. The results are published in the journal Current Biology.

The participants had to choose between two different snacks. The further they moved the slider to the left or right end, the more confident they were in their choice. © AG Mormann/Uni Bonn

You are sitting in a café and want to enjoy a piece of cake with your cappuccino. The Black Forest gateau is just too rich for you and is therefore quickly eliminated. Choosing between the carrot cake and the rhubarb crumble is much trickier: The warm weather favors the refreshingly fruity cake. Carrot cake, however, is one of your all-time favorites. So what to do?

Every day we have to make decisions, and we are much more confident about some of them than others. Researchers at the University Hospital Bonn have now identified nerve cells in the brain whose activity indicates the confidence in decisions. A total of twelve men and women took part in their experiment. “We showed them photos of two different snacks, for example a chocolate bar and a bag of chips,” explains Prof. Dr. Dr. Florian Mormann from the Department of Epileptology. “They were then asked to use a slider to indicate which of these alternatives they would rather eat.” The more they moved the slider from its center position towards the left or right photo, the more confident they were in their decision.

Fire rate and confidence are related

Participants had to judge a total of 190 different snack pairs in this way. At the same time, the scientists recorded the activity of 830 nerve cells each in the so-called temporal lobe. “We discovered that the frequency of the electrical pulses in some neurons, in other words their ‘firing rate’, changed with increasing decision confidence,” explains Mormann’s colleague Alexander Unruh-Pinheiro. “For instance, some fired more frequently, the more confident the respective test person was in their decision.”

Ultra-fine electrodes implanted in the temporal lobes of epileptic patients enable researchers to visualize the activity of individual nerve cells. © Christian Burkert

It is the first time that such a correlation between activity and decision confidence has been identified. The affected neurons are located in a brain region that plays a role in memory processes. “It is possible that we not only store what decision we made, but also how confident we were in it,” speculates Mormann. “Perhaps such a learning process saves us from future wrong decisions.”

Ethical reasons usually prohibit the study of the state of individual neurons in living humans. However, the participants in the study suffered from a severe form of epilepsy. In this form of the disease, the characteristic seizures always start in the same area of the brain. One possible treatment is therefore to remove this epileptic focus surgically. To pinpoint the exact location of the defective site, the doctors at the Clinic for Epileptology implant several electrodes in the patient. These are distributed over the entire potentially affected area. At the same time, they also allow an insight into the functioning of individual nerve cells in the brain.

Researchers at the University of Bonn were originally looking for a completely different phenomenon: When we make a decision, we assign a subjective value to each of the alternatives. “There is evidence that this subjective value is also reflected in the activity of individual neurons,” says Mormann. “The fact that we instead came across this connection between fire behavior and decision confidence surprised even us.”

References: Alexander Unruh-Pinheiro, Michael R. Hill, Bernd Weber, Jan Boström, Christian E. Elger, Florian Mormann: Single Neuron Correlates of Decision Confidence in the Human Medial Temporal Lobe. Current Biology; http://dx.doi.org/10.1016/j.cub.2020.09.021 link: https://www.cell.com/current-biology/fulltext/S0960-9822(20)31352-X?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS096098222031352X%3Fshowall%3Dtrue#main-menu

Provided by University Of Bonn