Posts Tagged ‘fear’

Summary: Newly identified ‘extinction neurons’ in the hippocampus suppress fearful memories when activated, and allow the memories to return when deactivated. The findings may provide new treatment avenues for PTSD, phobias, and anxiety.

Neuroscientists at The University of Texas at Austin have discovered a group of cells in the brain that are responsible when a frightening memory re-emerges unexpectedly, like Michael Myers in every “Halloween” movie. The finding could lead to new recommendations about when and how often certain therapies are deployed for the treatment of anxiety, phobias and post-traumatic stress disorder (PTSD).

In the new paper, out today in the journal Nature Neuroscience, researchers describe identifying “extinction neurons,” which suppress fearful memories when they are activated or allow fearful memories to return when they are not.

Since the time of Pavlov and his dogs, scientists have known that memories we thought we had put behind us can pop up at inconvenient times, triggering what is known as spontaneous recovery, a form of relapse. What they didn’t know was why it happened.

“There is frequently a relapse of the original fear, but we knew very little about the mechanisms,” said Michael Drew, associate professor of neuroscience and the senior author of the study. “These kinds of studies can help us understand the potential cause of disorders, like anxiety and PTSD, and they can also help us understand potential treatments.”

One of the surprises to Drew and his team was finding that brain cells that suppress fear memories hid in the hippocampus. Traditionally, scientists associate fear with another part of the brain, the amygdala. The hippocampus, responsible for many aspects of memory and spatial navigation, seems to play an important role in contextualizing fear, for example, by tying fearful memories to the place where they happened.

The discovery may help explain why one of the leading ways to treat fear-based disorders, exposure therapy, sometimes stops working. Exposure therapy promotes the formation of new memories of safety that can override an original fear memory. For example, if someone becomes afraid of spiders after being bitten by one, he might undertake exposure therapy by letting a harmless spider crawl on him. The safe memories are called “extinction memories.”

“Extinction does not erase the original fear memory but instead creates a new memory that inhibits or competes with the original fear,” Drew said. “Our paper demonstrates that the hippocampus generates memory traces of both fear and extinction, and competition between these hippocampal traces determines whether fear is expressed or suppressed.”

Given this, recommended practices around the frequency and timing of exposure therapy may need revisiting, and new pathways for drug development may be explored.

In experiments, Drew and his team placed mice in a distinctive box and induced fear with a harmless shock. After that, when one of the mice was in the box, it would display fear behavior until, with repeated exposure to the box without a shock, the extinction memories formed, and the mouse was not afraid.

Scientists were able to artificially activate the fear and suppress the extinction trace memories by using a tool called optogenetics to turn the extinction neurons on and off again.

“Artificially suppressing these so-called extinction neurons causes fear to relapse, whereas stimulating them prevents fear relapse,” Drew said. “These experiments reveal potential avenues for suppressing maladaptive fear and preventing relapse.”

The studies were led by graduate student Anthony Lacagnina of The University of Texas at Austin, with contributions from Emma Brockway, Chelsea Crovetti, Francis Shue, Meredith McCarty and Kevin Sattler of The University of Texas; and Sean Lim, Sofia Leal Santos and Christine Denny of Columbia University.

https://neurosciencenews.com/ptsd-hippocampus-fear-10966/

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by PETER DOCKRILL

When bad things happen, we don’t want to remember. We try to block, resist, ignore – but we should perhaps be doing the opposite, researchers say.

A new study led by scientists in Texas suggests the act of intentionally forgetting is linked to increased cerebral engagement with the unwanted information in question. In other words, to forget something, you actually need to focus on it.

“A moderate level of brain activity is critical to this forgetting mechanism,” explains psychologist Tracy Wang from the University of Texas at Austin.

“Too strong, and it will strengthen the memory; too weak, and you won’t modify it.”

Trying to actively forget unwanted memories doesn’t just help prevent your brain from getting overloaded.

It also lets people move on from painful experiences and emotions they’d rather not recall, which is part of the reason it’s an area of active interest to neuroscientists.

“We may want to discard memories that trigger maladaptive responses, such as traumatic memories, so that we can respond to new experiences in more adaptive ways,” says one of the researchers, Jarrod Lewis-Peacock.

“Decades of research has shown that we have the ability to voluntarily forget something, but how our brains do that is still being questioned.”

Much prior research on intentional forgetting has focussed on brain activity in the prefrontal cortex, and the brain’s memory centre, the hippocampus.

In the new study, the researchers monitored a different part of the brain called the ventral temporal cortex, which helps us process and categorise visual stimuli.

In an experiment with 24 healthy young adults, the participants were shown pictures of scenes and people’s faces, and were instructed to either remember or forget each image.

During the experiment, each of the participants had their brain activity monitored by functional magnetic resonance imaging (fMRI) machines.

When the researchers examined activity in the ventral temporal cortex, they found that the act of forgetting effectively uses more brain power than remembering.

“Pictures followed by a forget instruction elicited higher levels of processing in [the] ventral temporal cortex compared to those followed by a remember instruction,” the authors write in their paper.

“This boost in processing led to more forgetting, particularly for items that showed moderate (vs. weak or strong) activation.”

Of course, forgetting specific images on demand in a contrived laboratory experiment is very different to moving on from painful or traumatic memories of events experienced in the real world.

But the mechanisms at work could be the same, researchers say, and figuring out how to activate them could be a huge benefit to people around the world who need to forget things, but don’t know how.

Especially since this finding in particular challenges our natural intuition to suppress things; instead, we should involve more rather than less attention to unwanted information, in order to forget it.

“Importantly, it’s the intention to forget that increases the activation of the memory,” Wang says.

“When this activation hits the ‘moderate level’ sweet spot, that’s when it leads to later forgetting of that experience.”

The findings are reported in JNeurosci.

https://www.sciencealert.com/to-forget-something-you-need-to-think-about-it-neuroscientists-reveal


Pinpoint stimulation of a cluster of nerve cells in the brains of mice encouraged timid responses to a perceived threat, whereas stimulation of an adjacent cluster induced boldness and courage.

Researchers at the Stanford University School of Medicine have identified two adjacent clusters of nerve cells in the brains of mice whose activity level upon sighting a visual threat spells the difference between a timid response and a bold or even fierce one.

Located smack-dab in the middle of the brain, these clusters, or nuclei, each send signals to a different area of the brain, igniting opposite behaviors in the face of a visual threat. By selectively altering the activation levels of the two nuclei, the investigators could dispose the mice to freeze or duck into a hiding space, or to aggressively stand their ground, when approached by a simulated predator.

People’s brains probably possess equivalent circuitry, said Andrew Huberman, PhD, associate professor of neurobiology and of ophthalmology. So, finding ways to noninvasively shift the balance between the signaling strengths of the two nuclei in advance of, or in the midst of, situations that people perceive as threatening may help people with excessive anxiety, phobias or post-traumatic stress disorder lead more normal lives.

“This opens the door to future work on how to shift us from paralysis and fear to being able to confront challenges in ways that make our lives better,” said Huberman, the senior author of a paper describing the experimental results. It was published online May 2 in Nature. Graduate student Lindsey Salay is the lead author.

Perilous life of a mouse
There are plenty of real threats in a mouse’s world, and the rodents have evolved to deal with those threats as best they can. For example, they’re innately afraid of aerial predators, such as a hawk or owl swooping down on them. When a mouse in an open field perceives a raptor overhead, it must make a split-second decision to either freeze, making it harder for the predator to detect; duck into a shelter, if one is available; or to run for its life.

To learn how brain activity changes in the face of such a visual threat, Salay simulated a looming predator’s approach using a scenario devised some years ago by neurobiologist Melis Yilmaz Balban, PhD, now a postdoctoral scholar in Huberman’s lab. It involves a chamber about the size of a 20-gallon fish tank, with a video screen covering most of its ceiling. This overhead screen can display an expanding black disc simulating a bird-of-prey’s aerial approach.

Looking for brain regions that were more active in mice exposed to this “looming predator” than in unexposed mice, Salay pinpointed a structure called the ventral midline thalamus, or vMT.

Salay mapped the inputs and outputs of the vMT and found that it receives sensory signals and inputs from regions of the brain that register internal brain states, such as arousal levels. But in contrast to the broad inputs the vMT receives, its output destination points were remarkably selective. The scientists traced these outputs to two main destinations: the basolateral amygdala and the medial prefrontal cortex. Previous work has tied the amygdala to the processing of threat detection and fear, and the medial prefrontal cortex is associated with high-level executive functions and anxiety.

Further inquiry revealed that the nerve tract leading to the basolateral amygdala emanates from a nerve-cell cluster in the vMT called the xiphoid nucleus. The tract that leads to the medial prefrontal cortex, the investigators learned, comes from a cluster called the nucleus reuniens, which snugly envelopes the xiphoid nucleus.

Next, the investigators selectively modified specific sets of nerve cells in mice’s brains so they could stimulate or inhibit signaling in these two nerve tracts. Exclusively stimulating xiphoid activity markedly increased mice’s propensity to freeze in place in the presence of a perceived aerial predator. Exclusively boosting activity in the tract running from the nucleus reuniens to the medial prefrontal cortex in mice exposed to the looming-predator stimulus radically increased a response seldom seen under similar conditions in the wild or in previous open-field experiments: The mice stood their ground, right out in the open, and rattled their tails, an action ordinarily associated with aggression in the species.

Thumping tails

This “courageous” behavior was unmistakable, and loud, Huberman said. “You could hear their tails thumping against the side of the chamber. It’s the mouse equivalent of slapping and beating your chest and saying, ‘OK, let’s fight!’” The mice in which the nucleus reuniens was stimulated also ran around more in the chamber’s open area, as opposed to simply running toward hiding places. But it wasn’t because nucleus reuniens stimulation put ants in their pants; in the absence of a simulated looming predator, the same mice just chilled out.

In another experiment, the researchers showed that stimulating mice’s nucleus reuniens for 30 seconds before displaying the “looming predator” induced the same increase in tail rattling and running around in the unprotected part of the chamber as did vMT stimulation executed concurrently with the display. This suggests, Huberman said, that stimulating nerve cells leading from the nucleus reunions to the prefrontal cortex induces a shift in the brain’s internal state, predisposing mice to act more boldly.

Another experiment pinpointed the likely nature of that internal-state shift: arousal of the autonomic nervous system, which kick-starts the fight, flight or freeze response. Stimulating either the vMT as a whole or just the nucleus reuniens increased the mice’s pupil diameter — a good proxy of autonomic arousal.

On repeated exposures to the looming-predator mockup, the mice became habituated. Their spontaneous vMT firing diminished, as did their behavioral responses. This correlates with lowered autonomic arousal levels.

Human brains harbor a structure equivalent to the vMT, Huberman said. He speculated that in people with phobias, constant anxiety or PTSD, malfunctioning circuitry or traumatic episodes may prevent vMT signaling from dropping off with repeated exposure to a stress-inducing situation. In other experiments, his group is now exploring the efficacy of techniques, such as deep breathing and relaxation of visual fixation, in adjusting the arousal states of people suffering from these problems. The thinking is that reducing vMT signaling in such individuals, or altering the balance of signaling strength from their human equivalents of the xiphoid nucleus and nucleus reuniens may increase their flexibility in coping with stress.

Reference:
Salay, L. D., Ishiko, N., & Huberman, A. D. (2018). A midline thalamic circuit determines reactions to visual threat. Nature. doi:10.1038/s41586-018-0078-2

http://med.stanford.edu/news/all-news/2018/05/scientists-find-fear-courage-switches-in-brain.html


The study simulated long-term consumption of three cups of coffee a day.

It is well known that memory problems are the hallmarks of Alzheimer’s disease. However, this dementia is also characterized by neuro-psychiatric symptoms, which may be strongly present already in the first stages of the disorder. Known as Behavioural and Psychological Symptoms of Dementia (BPSD), this array of symptoms — including anxiety, apathy, depression, hallucinations, paranoia and sundowning (or late-day confusion) — are manifested in different manners depending on the individual patient, and are considered the strongest source of distress for patients and caregivers.


Coffee and caffeine: good or bad for dementia?

Caffeine has recently been suggested as a strategy to prevent dementia, both in patients with Alzheimer’s disease and in normal ageing processes. This is due to its action in blocking molecules — adenosine receptors — which may cause dysfunctions and diseases in old age. However, there is some evidence that once cognitive and neuro-psychiatric symptoms develop, caffeine may exert opposite effects.

To investigate this further, researchers from Spain and Sweden conducted a study with normal ageing mice and familial Alzheimer’s models. The research, published in Frontiers in Pharmacology, was conducted from the onset of the disease up to more advanced stages, as well as in healthy age-matched mice.

“The mice develop Alzheimer’s disease in a very close manner to human patients with early-onset form of the disease,” explains first author Raquel Baeta-Corral, from Universitat Autònoma de Barcelona, Spain. “They not only exhibit the typical cognitive problems but also a number of BPSD-like symptoms. This makes them a valuable model to address whether the benefits of caffeine will be able to compensate its putative negative effects.”

“We had previously demonstrated the importance of the adenosine A1 receptor as the cause of some of caffeine’s adverse effects,” explains Dr. Björn Johansson, a researcher and physician at the Karolinska University Hospital, Sweden.

“In this study, we simulated a long oral treatment with a very low dose of caffeine (0.3 mg/mL) — equivalent to three cups of coffee a day for a human — to answer a question which is relevant for patients with Alzheimer’s, but also for the ageing population in general, and that in people would take years to be solved since we would need to wait until the patients were aged.”

Worsened Alzheimer’s symptoms outweigh cognition benefits

The results indicate that caffeine alters the behavior of healthy mice and worsens the neuropsychiatric symptoms of mice with Alzheimer’s disease. The researchers discovered significant effects in the majority of the study variables — and especially in relation to neophobia (a fear of everything new), anxiety-related behaviors, and emotional and cognitive flexibility.

In mice with Alzheimer’s disease, the increase in neophobia and anxiety-related behaviours exacerbates their BPSD-like profile. Learning and memory, strongly influenced by anxiety, got little benefit from caffeine.

“Our observations of adverse caffeine effects in an Alzheimer’s disease model, together with previous clinical observations, suggest that an exacerbation of BPSD-like symptoms may partly interfere with the beneficial cognitive effects of caffeine. These results are relevant when coffee-derived new potential treatments for dementia are to be devised and tested,” says Dr. Lydia Giménez-Llort, researcher from the INc-UAB Department of Psychiatry and Legal Medicine, Universitat Autònoma de Barcelona, and lead researcher of the project.

The results of the study form part of the PhD thesis of Raquel Baeta-Corral, first author of the article, and are the product of a research led by Lydia Giménez-Llort, Director of the Medical Psychology Unit, Department of Psychiatry and Legal Medicine and researcher at the UAB Institute of Neuroscience, together with Dr Björn Johansson, Researcher at the Department of Molecular Medicine and Surgery, Karolinska Institutet and the Department of Geriatrics, Karolinska University Hospital, Sweden, under the framework of the Health Research Fund project of the Institute of Health Carlos III.

Long-term caffeine worsens symptoms associated with Alzheimer’s disease

BY JEFF HADEN

Courage isn’t just a willingness to confront pain or fear. Courage, like character, also involves doing the right thing when no one is watching… or will ever know what you’ve done.

When you think of courage you may think of physical bravery, but there are many other forms of courage. After all, “Courage is not the absence of fear, but the triumph over it.” That means courage – sometimes remarkable courage – is required in business and entrepreneurship: Taking a chance when others will not; following your vision, no matter where it takes you; standing up for what you believe in, especially when your beliefs are unpopular; or simply doing the right thing even though easier options exist.

1. They Have the Courage to Believe the Unbelievable
Most people try to achieve the achievable. That’s why most goals and targets are incremental rather than massive or even inconceivable. Incremental is safe. Believable is safe. Why? Because you’re less likely to fall short. You’re less likely to fail. You’re less likely to lose credibility and authority. A few people do expect more from themselves and from others. But they don’t stop there. They also show you how to get to “more.” And they bring you along for what turns out to be an unbelievable ride.

2. They Have the Courage to be Patient
When things go poorly, giving up or making a change is often the easiest way out. It takes more courage to be patient, to believe in yourself, or to show people you believe in them. Showing patience in others also shows you care. And when you show you truly care about the people around you, even when others clamor for a change, they may find ways to do things that will amaze everyone — including themselves.

3. They Have the Courage to Say, “No.”
They have the courage to say no to requests for unusual favors, for unreasonable demands on your time, or to people who are only concerned with their own interests? Saying yes is the easy move. Saying no, when you know you’ll later resent or regret having said yes, is much harder — but is often the best thing to do, both for you and for the other person.

4. They Have the Courage to Take an Unpopular Stand
Many people try to stand out in a superficial way: clothes, or interests, or public displays of support for popular initiatives. They’re conspicuous for reasons of sizzle, not steak. It takes real courage to take an unpopular stand. And it takes real courage to take risks not just for the sake of risk but for the sake of the reward you believe is possible, and by your example to inspire others to take a risk in order to achieve what they believe is possible.

5. They Have the Courage to Ask for Help
No one does anything worthwhile on his or her own. Even the most brilliant, visionary, fabulously talented people achieve their success through collective effort. Still, it takes courage to sincerely and humbly say, “Can you help me?” Asking for help shows vulnerability. But it also shows respect and a willingness to listen. And those are qualities every great leader possesses.

6. They Have the Courage to Show Genuine Emotion
Acting professionally is actually fairly easy. Acting professionally while also remaining openly human takes courage–the willingness to show sincere excitement, sincere appreciation, and sincere disappointment, not just in others, but also in yourself. It takes real bravery to openly celebrate, openly empathize, and openly worry. It’s hard to be professional and also remain a person.

7. They Have the Courage to Forgive
When an employee makes a mistake –- especially a major mistake –- it’s easy to forever view that employee through the lens of that mistake. But one mistake, or one weakness, or one failing is also just one part of a person. It’s easy to fire, to punish, to resent; it’s much harder to step back, set aside a mistake, and think about the whole person. It takes courage to move past and forget mistakes and to treat an employee, a colleague, or a friend as a whole person and not just a living reminder of an error, no matter how grievous that mistake may have been.

8. They Have the Courage to Stay the Course
It’s easy to have ideas. It’s a lot harder to stick with your ideas in the face of repeated failure. It’s incredibly hard to stay the course when everyone else feels you should give up. Every day, hesitation, uncertainty, and failure causes people to quit. It takes courage to face the fear of the unknown and the fear of failure. But how many ideas could turn out well if you trust your judgment, your instincts, and your willingness to overcome every obstacle?

9. They Have the Courage to Lead by Permission
Every boss has a title. In theory that title confers the right to direct, to make decisions, to organize and instruct and discipline. The truly brave leader forgets the title and leads by making people feel they work with, not for, that person. It takes courage to not fall back on a title but to instead work to earn respect–and through gaining that respect earn the permission to lead.

10. They Have the Courage to Succeed Through Others
Great teams are made up of people who know their roles, set aside personal goals, willingly help each other, and value team success over everything else. Great business teams win because their most talented members are willing to sacrifice to make others successful and happy.

11. They Have the Courage to Say, “I’m Sorry.”
We all make mistakes and we all have things we need to apologize for: Words, actions, omissions, failing to step up, step in, show support. It takes courage to say, “I’m sorry.” It takes even more courage not to add, “But I was really mad, because…” or “But I did think you were…” or any words that in any way places the smallest amount of blame back on the other person.

12. They Have the Courage to Take the Hit
A customer is upset. A coworker is frustrated. A supplier feels shortchanged. An investor is impatient. Whatever the issue, the courageous people step up and take the hit. They support others. They support their teams. They willingly take responsibility and draw negative attention to themselves because to do otherwise is not just demotivating and demoralizing, it also undermines other people’s credibility and authority. Courageous people never throw others under the bus, even if that shines a negative spotlight on themselves.

http://www.inc.com/ss/jeff-haden/qualities-remarkably-courageous-people