Posts Tagged ‘stress’

The 60 souls that signed on for Dr. Alain Brunet’s memory manipulation study were united by something they would rather not remember. The trauma of betrayal.

For some, it was infidelity and for others, a brutal, unanticipated abandonment. “It was like, ‘I’m leaving you. Goodbye,” the McGill University associate professor of psychiatry says.

In cold, clinical terms, his patients were suffering from an “adjustment disorder” due to the termination (not of their choosing) of a romantic relationship. The goal of Brunet and other researchers is to help people like this — the scorned, the betrayed, the traumatized — lose their total recall. To deliberately forget.

Over four to six sessions, volunteers read aloud from a typed script they had composed themselves — a first-person account of their breakup, with as many emotional details as possible — while under the influence of propranolol, a common and inexpensive blood pressure pill. The idea was to purposely reactivate the memory and bring the experience and the stinging emotions it aroused to life again. “How did you feel about that?” they were asked. How do you feel right now? And, most importantly: Has your memory changed since last week?

The investigators had hypothesized that four to six sessions of memory reactivation under propranolol would be sufficient to dramatically blunt the memories associated with their “attachment injury.” Decrease the strength of the memory, Brunet says, and you decrease the strength of the pain.

The study is now complete, and Brunet is hesitant to discuss the results, which have been submitted to a journal for peer review and publication. However, the participants “just couldn’t believe that we could do so much in such a small amount of time,” he confides.

“They were able to turn the page. That’s what they would tell us — ‘I feel like I’ve turned the page. I’m no longer obsessed by this person, or this relationship.’”

Brunet insists he isn’t interested in deleting or scrubbing painful memories out entirely. The idea of memory erasure, of finding the cellular imprint of a specific, discreet memory in the brain, of isolating and inactivating the brain cells behind that memory, unnerves him. ‘It’s not going to come from my lab,” he says, although others are certainly working on it. Memories are part of who we are, what forms our identity, what makes us authentic, “and as long as only one choice exists right now, and it’s toning down a memory, we feel on very solid and comfortable ground,” ethically speaking, Brunet says.

“However, if one day you had two options — I can tone down your memory, or I can remove it altogether, from your head, from your mind — what would you choose?”

The choice might soon be yours.

“If you could erase the memory of the worst day of your life, would you,” Elizabeth Phelps and Stefan Hofmann write in the journal, Nature. “How about your memory of a person who has caused you pain?”

What was once purely science fiction is moving ever closer to clinical reality. Researchers are working on techniques and drugs that might enable us to edit our memories or at least seriously dull their impact — to make the intolerable bearable — by, say, swallowing a pill to block the synaptic changes needed for a memory to solidify. A pill that could be taken hours, even months or years after the event.

Much of the work is based on the theory of memory reconsolidation – the belief that the mere conscious act of recalling or conjuring a memory makes it vulnerable to tinkering or meddling. When a memory is evoked, a reconsolidation window opens for a brief period of time (two to five hours, according to Brunet), during which time the memory returns to a state of “lability.” It becomes pliable, like Play-Doh. It also becomes susceptible to modification, before “reconsolidating” or re-storage. The thought is that propranolol interferes with proteins in the brain needed to lock down the memory again.

A similar line of thinking holds that a memory isn’t an exact impression of the original event, an Iphone video of the past, says Boston University neuroscientist Steve Ramirez. Rather it’s more like Plato’s wax tablet. Press a signet ring into the wax and it leaves an imprint, but the wax can melt when we recall the memory, form again and then melt all over again. “Memory is dynamic,” Ramirez says. It isn’t static. Memories can also be updated with new information when they’re recalled, like hitting “save as” every time you go into a Word file.

But the idea that memories can be edited, softened or dialled down, is more than a little discomfiting to some, and not just for what it means for eyewitness testimony. “We’re not reliable narrators when it comes to some details, and sometimes even entire scenarios,” Ramirez says. More profoundly, without good and bad memories it’s hard to imagine how we would know how to behave, says Dr. Judy Illes, professor of neurology and Canada Research Chair in neuroethics at the University of British Columbia.

Learning doesn’t occur without memory. How do we learn from a bad relationship, if we can’t remember it? “And so now, if we pre-select what memories stick and don’t stick, it almost starts to be like the eugenics of memory,” Illes says. “We ought to think carefully about that.”

She has absolutely no qualms about using memory manipulation for people suffering desperately from post-traumatic stress disorder, people whose burden of suffering from horrifying experiences exceeds any moral argument against using it.

“To me, a PTSD that is profound and debilitating is like a disease of any other and, to the extent that we can have an intervention that treats it, we should vigorously pursue it.”

Even the heartbroken recruited for Brunet’s study were experiencing symptoms congruent with PTSD. We’re geared to form attachments, he says, and not so much to detach.

But memory manipulation has a slippery slope. Would it bleed into not-so-disabling disorders? If someone misbehaves at a cocktail party and would really sooner forget what happened, is that an appropriate use? Isn’t it good to be embarrassed by your past behaviour, to keep you from doing it again? What about war fighters, asks Illes. “If we had a drug that can mitigate a bad memory, could we possibly use it in advance of an act to actually prevent a memory from forming, and therefore enable people to fight less fearfully, and more fiercely, because there’s no consolidation of the acts of crime, or acts of war?”

The pull of moral responsibility — “one’s future ‘oughtness’” — is grounded in our life story, writes bioethicist Dr. Peter DePergola in the Journal of Cognition and Neuroethics. Using blood pressure pills or some other intervention like, say, transcranial direct current stimulation, to deaden or blast away memories of trauma “ultimately undermines one’s ability to seek, identify and act on the good,” DePergola argues.

And how do you manipulate a bad memory, without risking happy, shiny, positive ones? What does a memory even look like in the brain? Can we visualize it? Can we see what happens when positive and negative memories form? And where would all the bad memories go? Saved in glass bottles in the Ministry of Magic?

We can’t go into the brain and erase memories in an Eternal-Sunshine-of-the-Spotless-Mind kind of way, Ramirez says, at least not yet. We can’t touch or poke a memory. However, scientists are starting to get unprecedented glimpses into the physical structure of memory in the brain. The goal is to identify the brain cells a particular memory gloms onto, and artificially manipulate those cells.

The challenge is that human memories aren’t localized to one specific location in the brain. There’s no spot X you can point to, and say, Aha! There it is. Rather, they’re scattered throughout the organ. The sights and sounds and smells and emotions of a memory are going to recruit different corners of the brain that are involved in processing the sights and sounds and smells and emotions, Ramirez says.

“Right now, there are a lot of memories that are asleep in your brain. If I asked you, ‘what did you do last night?’, that memory just woke up. How did that happen? You just did that effortlessly in, like, 500 milliseconds. And yet we don’t know how that process works.”

However, we know that it does happen, and scientists have some pretty good indications of what happens physiologically when we recall a memory, and what it means for that memory to become awake again.

American-Canadian neurosurgeon Wilder Penfield was one of the first to hint at where to look. When Penfield stimulated cells in the hippocampus of people who were undergoing surgery for epilepsy in the 1940s with mild jolts of electricity, specific episodic memories — memories of actual experiences — suddenly popped into their minds. “It was like, ‘I have no idea why, but I’m randomly remembering my 16th birthday and I was walking my cat,’’” Ramirez said on a National Geographic podcast earlier this year.

In experiments that helped open the floodgates, Ramirez and other scientists at MIT reported that they could identify — in mice — the cells that make up part of an engram, the coding for a specific memory, and reactive those same cells using a technology called optogenetics.

Briefly, here’s what they did: Viruses were inserted into the brain cells of genetically modified mice that made the cells glow green in response to light. Next, the researchers isolated cells in the hippocampus of a mouse as the rodents were forming a specific memory — in this case, the memory of receiving a mild electric foot shock while exploring a box.

A day later, the mouse was placed in a different box — different smells, different floor, meaning there should be no reason for them to be fearful. But when those memory cells were activated with a laser, the mouse froze in fear.

More recently, in a paper published earlier this year, Ramirez and co-author Briana Chen mapped out which cells in the hippocampus were being activated when male mice made new memories of positive (meeting a female mouse) and negative (those mild electric foot zaps again) experiences. They were able to trigger the memories again later, using laser light to activate the memory cells. When memory cells in the bottom part of the hippocampus were stimulated, it seemed to dial up the negative memories. But stimulating memory cells in the top part of the hippocampus seemed to dial them down.

The goal, says Ramirez, is to artificially activate positive memories to overwrite the bad ones — in a sense, using the brain as a drug. “In depression, there is a bias toward negative thinking,” Ramirez says. We’ve been using drugs like Xanax and Prozac for decades, but we haven’t really advanced all that much since the 1970s, Ramirez says. “Maybe we need to tackle these kinds of disorders from all angles.”

Ten years ago, Sheena Josselyn’s lab was the first to offer fairly convincing evidence that we can erase a specific fear memory in mice, without erasing every one of the rodent’s fears. The University of Toronto neuroscientist used a toxin to destroy a handful of neurons housing the memory “It wasn’t like a huge legion. If you take out the entire brain, the mouse doesn’t remember a darn thing.”

That’s obviously not technically, or ethically ideal in humans. No one is talking about ablating neurons in people, or injecting viruses into human brain cells to make them glow green. “But it does tell us that in order to manipulate a memory in people we don’t have to give an entire, systemic thing,” Josselyn says. Rather, we could go in and just hit the target neurons using some kind of smart bomb.

Mice aren’t humans, and efforts to translate the results from animal experiments to healthy humans have been mixed, Phelps and Hoffman note in their Nature article. Still, whether it’s beta-blockers like propranolol, or ecstasy or ketamine or other drugs being tested that might block the synthesis of proteins required to lock down a memory after it’s been retrieved, Ramirez and others believe we could tackle the emotional “oomph,” the psychological sting, of a traumatic memory, while leaving the autobiographic experience — the actual, conscious recollection of the event — intact. No, you may not be able to erase the memory of the “venomous, evil snake that is my ex,” as one Redditor asked Ramirez. There isn’t a memory anti-venom. With memory manipulation, people would still remember the breakup, and the person, but the toxic, gut-twisting emotions associated with it would melt, like ice cream in the sun. And, just as doctors shouldn’t hand out anti-depressants to the entire population of Boston, Ramirez says memory manipulation should be reserved for those suffering crippling anxiety, depression or other symptoms.

Betrayal and abandonment themselves are “no small stuff,” adds Brunet. “This is the material Greek tragedies are made of.” People can become hyper vigilant, he says. They have intrusive thoughts. Everything around them reminds them of the former relationship. “It affects negatively your world views, your self esteem and the trust you can place in other people,” Brunet says.

However, a memory buster is challenging, Illes, of UBC says, because it interferes with our experience as humans.

Our brains are hardwired to remember emotionally charged events. “Do you remember where you were on 9/11? Do you remember five supermarkets ago?” Illes asks.

Our memories are so closely interrelated and interconnected, she adds, that you can’t just pull one brick out without the integrity of the entire wall being affected.

“Go back to your dating question,” Illes says as a thought experiment. “We have a bad relationship. Unless two people are on an isolated island and don’t interact with other humans, your bad relationship has other people in there. And, so, how do you remove all the memories associated with all the complexities that we have on a daily basis?”

Memories give us a sense of consciousness, she says, of who we are and what we know to be right and wrong and moral and immoral.

A prescient 2003 report from the U.S. President’s Council on Bioethics asked whether the then-emerging field of memory-alteration would mean abandoning our own truthful identities.

“Armed with new powers to ease the suffering of bad memories, we might come to see all psychic pain as unnecessary and in the process come to pursue a happiness that is less than human,” the authors wrote, “an unmindful happiness, unchanged by time and events, unmoved by life’s vicissitudes.”

Steve Ramirez was running in the Boston marathon in 2013 when two crude pressure cooker bombs detonated 12 seconds apart near the finish line, killing three and injuring several hundred more. The sights, the sounds, the smells — “they helped carve a very deep corner into my personality,” he says.

“It exposed a darker aspect of humanity, but I wouldn’t really find any personal gain in not knowing that corner, either.”

If you could erase the worst memory of your life, would you? Scientists are working on a pill for that

Thanks to Kebmodee for bringing this to the It’s Interesting community.

by Lisa Rapaport

Kids who have more supportive experiences with family, friends, and people in their school and community may be less likely to have psychological or relationship troubles in adulthood, a new study suggests.

Adverse childhood experiences (ACEs) like abuse, neglect, violence, and parental absence have long been linked to lasting negative effects on physical and mental health, researchers note in JAMA Pediatrics. But less is known about whether positive experiences make it easier for kids to cope, or what happens with children whose lives have mix of negative and positive experiences

For the current study, researchers surveyed 6,118 adults about how often in childhood they felt able to talk to family and friends about feelings; felt their family stood by them during difficult times; enjoyed participating in community traditions; felt a sense of belonging in high school; felt supported by friends; had at least two nonparent adults who took an interest in them; and felt safe and protected by an adult in their home.

Overall, adults who reported six to seven of these positive childhood experiences were 72% less likely to have depression or at least 14 poor mental health days each month than adults who reported no more than two positive childhood experiences. Even three to five positive experiences were tied to a 50% lower likelihood of depression or poor mental health than two or fewer.

These associations held true even when respondents reported multiple adverse childhood experiences.

“The absence of the types of positive childhood experiences we assessed in our study is very stressful for a child,” said lead study author Christina Bethell of the Bloomberg School of Public Health at Johns Hopkins University in Baltimore.

“Without positive nurturance, children’s stress hormones can get stuck on high and this impacts how their brain develops in ways that can make it hard for them to experience safety, relaxation and to become open, curious and learn to have positive relationships with others,” Bethell said by email.

The association between positive life experiences and better adult mental health and relationships persisted even among people who experienced ACEs during childhood.

Compared to participants who reported no more than two positive childhood experiences, people who experienced six to seven positive childhood experiences were also more than three times more likely to report that as adults, they “always” got the social and emotional support they needed.

When people had no more than two positive childhood experiences, only about one-third reported always getting the social and emotional support they needed – even when they didn’t have a history of ACEs.

The study doesn’t prove that positive childhood experiences impact adult mental health or relationships.

“In fact, people with poor mental health might be less likely to view their childhood experiences as positive,” said Dr. Rebecca Dudovitz, a researcher at the David Geffen School of Medicine at the University of California Los Angeles.

“It might actually be that adults with depression remember their childhood differently than adults without depression,” Dudovitz, who wasn’t involved in the study, said by email.

Parents may not be able to prevent adverse childhood experiences, but they can help kids become resilient, said Dr. Angelica Robles, a developmental-behavioral pediatrician at Novant Health in Charlotte, North Carolina, who wasn’t involved in the study.

“Parents can accomplish this by simply talking about feelings with their children, standing by their children during difficult times, and showing interest in their daily lives,” Robles said by email. “The child will then feel safe, and it is in this sense of security in the face of stress that the child learns to flourish.”

https://www.reuters.com/article/us-health-childhood/positive-childhood-experiences-tied-to-better-adult-mental-health-idUSKCN1VU2CP

by Carly Cassella

Sticks and stones may break your bones, but name-calling could actually change the structure of your brain.

A new study has found that persistent bullying in high school is not just psychologically traumatising, it could also cause real and lasting damage to the developing brain.

The findings are drawn from a long-term study on teenage brain development and mental health, which collected brain scans and mental health questionnaires from European teenagers between the ages of 14 and 19.

Following 682 young people in England, Ireland, France and Germany, the researchers tallied 36 in total who reported experiencing chronic bullying during these years.

When the researchers compared the bullied participants to those who had experienced less intense bullying, they noticed that their brains looked different.

Across the length of the study, in certain regions, the brains of the bullied participants appeared to have actually shrunk in size.

In particular, the pattern of shrinking was observed in two parts of the brain called the putamen and the caudate, a change oddly reminiscent of adults who have experienced early life stress, such as childhood maltreatment.

Sure enough, the researchers found that they could partly explain these changes using the relationship between extreme bullying and higher levels of general anxiety at age 19. And this was true even when controlling for other types of stress and co-morbid depressive symptoms.

The connection is further supported by previous functional MRI studies that found differences in the connectivity and activation of the caudate and putamen activation in those with anxiety.

“Although not classically considered relevant to anxiety, the importance of structural changes in the putamen and caudate to the development of anxiety most likely lies in their contribution to related behaviours such as reward sensitivity, motivation, conditioning, attention, and emotional processing,” explains lead author Erin Burke Quinlan from King’s College London.

In other words, the authors think all of this shrinking could be a mark of mental illness, or at least help explain why these 19-year-olds are experiencing such unusually high anxiety.

But while numerous past studies have already linked childhood and adolescent bullying to mental illness, this is the very first study to show that unrelenting victimisation could impact a teenager’s mental health by actually reshaping their brain.

The results are cause for worry. During adolescence, a young person’s brain is absolutely exploding with growth, expanding at an incredible place.

And even though it’s normal for the brain to prune back some of this overabundance, in the brains of those who experienced chronic bullying, the whole pruning process appears to have spiralled out of control.

The teenage years are an extremely important and formative period in a person’s life, and these sorts of significant changes do not bode well. The authors suspect that as these children age, they might even begin to experience greater shrinkage in the brain.

But an even longer long-term study will need to be done if we want to verify that hunch. In the meantime, the authors are recommending that every effort be made to limit bullying before it can cause damage to a teenager’s brain and their mental health.

This study has been published in Molecular Psychiatry.

https://www.sciencealert.com/chronic-bullying-could-actually-reshape-the-brains-of-teens

By Rachael Rettner

Many people tend to look back on the past with rose-colored glasses, remembering the good times and the good feelings…while forgetting the bad.

But a new study suggests that heavy marijuana users may have some trouble letting go of negative emotions tied to memories — a phenomenon that’s also seen in people with depression. Earlier research has also linked marijuana use with depression.

Although the new results are very preliminary, the findings, presented here on Friday (May 25) at the annual meeting of the Association for Psychological Science, may offer clues about the link between marijuana use and depression.

Rose-colored memories

The study explored a psychological phenomenon called “fading affect bias,” in which people tend to hold on to positive feelings tied to their memories more than they hold on to negative feelings. In other words, negative feelings related to our memories fade faster than positive ones.

Psychologists have hypothesized that this phenomenon, which is generally seen in people without mental health conditions, may serve as a sort of “psychological immune system,” said study lead author Daniel Pillersdorf, a graduate student in psychology at the University of Windsor in Ontario. This may be “so that we think more pleasantly in general, and don’t have that cognitive burden of holding on to negative emotions associated with memories,” Pillersdorf said.

Some previous studies have suggested that this fading affect bias may be different for people who use drugs, but no studies have looked at whether marijuana use could affect this phenomenon.

In the new study, the researchers analyzed information from 46 heavy marijuana users — most of whom used the drug at least four times a week — and 51 people who didn’t use marijuana. Participants were asked to recall, and provide written descriptions of, three pleasant memories and three unpleasant memories from the past year. The participants were then asked to rate the intensity of emotion tied to those memories, on a scale of negative 10, meaning extremely unpleasant, to positive 10, or extremely pleasant. They rated their emotions both at the time the memory was made, and at the current time. (Marijuana users were not under the influence at the time the researchers asked them the questions.)

The researchers found that both marijuana users and non-users showed fading affect bias, but for marijuana users, the fading was a lot less.

“They were hanging on to that unpleasant affect over time, much more” than non-users, Pillersdorf told Live Science. “They were less able … to shed that unpleasantness associated with their memories.”

The study also found that marijuana users tended to recall life events in more general terms than specific ones. For example, when asked about a happy event in the past year, marijuana users were more likely to respond with general or broad answers such as “I went on vacation,” rather than recalling a specific event or day, such as “I attended my college graduation.” This phenomenon is known as over-general autobiographical memory, and it’s also linked with depression, Pillersdorf said.

It’s important to note that the new study found only an association and cannot determine why marijuana users show less fading affect bias, and more overgeneral memory, than non-users.

Link with depression?

Even so, the new findings agree with previous research that has found a link between heavy marijuana use and depression. However, researchers don’t know why marijuana and depression are linked — it could be that marijuana use plays a role in developing depression, or that people who are already depressed are more likely to use the drug. [7 Ways Marijuana May Affect the Brain]

Based on the new findings, one hypothesis is that the decreased “fading” of negative memories in marijuana users could be contributing to the development or continuing of depression, Pillersdorf said. “It may be that, chronic or frequent cannabis use is putting [a person] more at risk for the development or continuing of depression,” he said. However, Pillersdorf stressed that this is just a hypothesis that would need to be investigated with future research.

To further investigate the link, researchers will need to study marijuana users and non-users over long periods of time. For example, researchers could start with people in their late teens or early 20s, who don’t have depression, and see if those who use marijuana frequently are more likely to eventually develop depression than non-users.

Additional studies could also investigate whether other substances have an effect on fading affect bias, Pillersdorf said.

The study has not yet been published in a peer-reviewed journal.

https://www.livescience.com/62679-marijuana-negative-memories.html?utm_source=notification

Exposure to early life trauma can lead to poor physical and mental health in some individuals, which can be passed on to their children. Studies in mice show that at least some of the effects of stress can be transmitted to offspring via environmentally-induced changes in sperm miRNA levels.

A new epigenetics study raises the possibility that the same is true in humans. It shows for the first time that the levels of the same two sperm miRNAs change in both men and mice exposed to early life stress. In mice, the negative effects of stress are transmitted to offspring. The study is published On May 23rd in Translational Psychiatry.

“The study raises the possibility that some of the vulnerability of children is due to Lamarckian type inheritance derived from their parents’ experiences,” said Larry Feig, Ph.D., professor of Developmental, Molecular and Chemical Biology at Tufts University School of Medicine and member of the Cell, Molecular and Developmental Biology and Neuroscience programs at the Sackler School of Graduate Biomedical Sciences at Tufts.

The human part of the study utilized the Adverse Childhood Experiences (ACE) questionnaire as an indicator of men’s early life trauma. The ACE Study questionnaire includes 10 yes or no questions about one’s experiences until the age of 18, including physical, verbal, or sexual abuse, and physical or emotional neglect. Other questions relate to one’s family members. Four or more yes answers put one at significantly increased risk for future mental and physical health problems. According to a ChildTrends research brief published in 2014, a remarkably high percentage (~10 percent) of the population report scores at or above this cutoff.

miRNAs constitute a newly appreciated type of gene regulator, where each miRNA controls a distinct set of genes. Until recently, sperm from fathers were thought to contribute only DNA to the mother’s egg upon fertilization, but new data in mice indicate that sperm also contribute miRNAs that influence the next generation. Sperm miRNA expression in humans is known to be affected by environmental factors, such as smoking and obesity, but no human study to date has documented the effects of stress.

The new study found that among 28 Caucasian male volunteers, the expression of two highly related sperm miRNAs, miR-449 and miR-34, were inversely proportional to the men’s ACE scores. Men with the most extensive early abuse (highest ACE scores) had as much as a 300-fold reduction in the two sperm miRNAs compared to men with the least abuse.

The idea that these changes can affect the next generation is supported by additional findings in the study, e.g.:

the same sperm miRNA changes that take place in men with high ACE scores also occur in mice exposed to early life social instability stress, which Feig’s lab has shown previously leads to anxiety and sociability defects in female offspring of stressed males for at least three generations;
these two sets of miRNAs are known to work together in mice to allow proper development of the brain and sperm;
in humans, miR-34c has been implicated in promoting early embryo development;
the mouse studies showed that the decline in these sperm miRNA levels is transmitted to the next generation; and
when these embryos mature, these miRNAs are also reduced in the sperm of their male offspring who pass on stress behaviors to their female offspring.
“This is the first study to show that stress is associated with altered levels of sperm miRNAs in humans. We are currently setting up a new, larger study in men, and additional experiments in mice that could yield further support for the idea that changes in these sperm miRNAs do, in fact, contribute to an elevation of stress-related disorders across generations,” said David Dickson, an M.D./Ph.D. student at Tufts and first author of the study.

“Looking to the future, we may be able to figure out a way to restore the low miRNA levels found in men exposed to extreme trauma, because epigenetic changes, such as stress-induced decreases in sperm miRNA expression, are reversible, unlike genetic changes that alter the DNA sequence,” Dickson added.

For example, obesity has been shown to alter specific sperm miRNA levels in men, while bariatric surgery and subsequent weight loss can reverse the changes. In addition, Isabelle Mansuy’s lab has reversed some of the negative effects of stress in mice across generations by exposing mice to an “enriched environment” that involves extensive social interactions, exercise and opportunities to explore their surroundings.

Feig pointed out that in addition to focusing on the potential transgenerational effects of stress, there is a growing appreciation that physicians should collect information on childhood trauma for the sake of the patients who are experiencing this early trauma.

This is because “childhood abuse, trauma and dysfunction adds to the risk of future physical and psychiatric maladies, and significant exposure to abusive and/or dysfunctional families is remarkably common. Moreover, sensitivity to PTSD has been shown to correlate with ACE score, implying the ACE questionnaire could be used as a screening tool to identify people who should take extra precaution to avoid potentially traumatic experiences,” he said.

“However, some people may not answer the ACE survey accurately due to inaccurate recall or because of the sensitive nature of many of the questions, particularly in settings that do not allow anonymity and/or where their answers could affect their future. Thus, discovery of unbiased markers for early trauma, like specific sperm miRNA content, could complement ACE surveys in some clinical settings to bolster preventative medicine,” he concluded.

The authors note that the relatively small sample size limits their ability to more deeply explore the association between ACE scores and miRNA expression. In addition, a longitudinal study with information on behavioral and psychological factors throughout adulthood, with repeated measurements of sperm miRNA content, could allow for further exploration on the effect of cumulative exposure to childhood trauma on miRNA.

Additional authors are Jessica Paulus, Sc.D., Tufts Medical Center as well as Tufts University School of Medicine and the Sackler School; Virginia Mensah, M.D., formerly in Feig’s lab with Women & Infants Hospital and the Warren Alpert Medical School at Brown University and now with the Reproductive Science Center of New Jersey; Janis Lem, Ph.D., Tufts Medical Center; Lorena Saavedra-Rodriguez, Ph.D., formerly a postdoctoral fellow in Feig’s laboratory at Tufts and now with a biopharmaceutical company; and Adrienne Gentry, D.O. and Kelly Pagidas, M.D., University of Louisville School of Medicine.

This study was supported by awards from the National Institute of Mental Health of the National Institutes of Health (R01MH107536), as well as the Tufts Center for Neuroscience Research (National Institute of Neurological Disorders and Stroke of the NIH, P30NS047243). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health or other funders.

Dickson, D.A., Paulus, J.K., Mensah, V., Lem, J., Saavedra-Rodriguez, L., Gentry, A., Pagidas, K., and Feig, L. A. (2018). Reduced levels of miRNAs 449 and 34 in sperm of mice and men exposed to early life stress. Translational Psychiatry. https://doi.org/10.1038/s41398-018-0146-2

https://now.tufts.edu/news-releases/early-life-trauma-men-associated-reduced-levels-sperm-micrornas


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

By Jacqueline Howard

Whether you call them gray hairs or stress highlights, world-renowned animal scientist and autism advocate Temple Grandin wants you to know that dogs may get them prematurely, too — possibly when stressed, such as being left at home alone.

Premature graying in dogs may be an indicator of anxiety and impulsivity, according to a study published in this month’s edition of the journal Applied Animal Behaviour Science, in which Grandin served as a co-author.

Camille King, an animal behaviorist and owner of the Canine Education Center in Denver, noticed a few years ago that many impulsive and anxious dogs seemed to be prematurely turning gray. When King told Grandin about her observations, Grandin said she encouraged King to lead the research.

“The first thing I thought of when she told me that were the presidents, and how they age and get prematurely gray,” said Grandin, professor of animal science at Colorado State University, referring to American commanders in chief.

“The fact that presidents turn prematurely gray was one of the things that made me encourage her to do the study,” Grandin said. “Basically, (the study findings) validated what she had seen in years of doing dog behavior work.”

The study, conducted at Northern Illinois University, involved 400 dogs, 4 years old or younger, with non-white-colored hair so the researchers could adequately determine degrees of graying.

“Normally, dogs wouldn’t be gray at age 4,” Grandin said.

The study, conducted at Northern Illinois University, involved 400 dogs, 4 years old or younger, with non-white-colored hair so the researchers could adequately determine degrees of graying.

“Normally, dogs wouldn’t be gray at age 4,” Grandin said.

Next, the researchers compared the survey responses with how much gray hair appeared on the dogs’ muzzles in their photos.
Grandin helped the researchers build a scoring system to measure the degrees of grayness: A score of 0 is “no gray;” 1 is for gray on the front of the nose only; 2 is for gray hair halfway up the muzzle; and 3 is “full gray.”

It turned out that a high grayness score was significantly and positively predicted by survey responses that indicated both high anxiety and impulsivity.

“Essentially, the results indicate that for each standard deviation increase in the measured trait, either anxiety or impulsiveness, the odds of being in a higher rating category of muzzle grayness increase 40% to 65%,” said Thomas Smith, a professor at Northern Illinois University’s Department of Educational Technology, Research and Assessment, who was a co-author of the study.

Smith added that he was initially skeptical that a dog’s premature muzzle grayness might be linked to anxiety and impulsiveness.

“However, when we analyzed the data, the results actually were striking,” he said. “I was surprised.”
A similar association between stress and premature graying possibly could be found in other mammals, outside of humans and dogs, but more research is needed, Grandin said.

The new study appears to extend what has been previously seen in people — the relationship between stress and gray hair — to dogs, said Matt Kaeberlein, a professor and co-director of the University of Washington’s Dog Aging Project, who was not involved in the new study.

“There are a few things about this study that I really like. One is that it nicely illustrates another way in which dogs and humans are similar, specifically in this case, the way we interact with our environment to experience stress. I like the innovative approach of applying facial image recognition to dogs,” Kaeberlein said.

“I do think it’s important to keep in mind that while hair graying is a useful ‘biomarker’ of aging and experienced stress, it is not particularly precise. We should avoid interpreting causation from correlation,” he said about the study. “Many dogs and people get gray hair for reasons unrelated to their perception of stress or anxiety, so while anxiety (or) stress appears to cause hair graying, gray hair is not necessarily caused by anxiety or stress. In other words, just because your dog gets gray hair doesn’t mean she or he is stressed out.”

For instance, more research is needed to determine how much genetics might play a role not only in premature graying in young dogs but also how a dog might respond to stress, Grandin said. She added that additional research could also determine how much of the study results were influenced by anxiety and impulsivity, respectively.

“There’s probably some genetic influence where some dogs that are impulsive and anxious don’t turn gray. You see, that would be your genetic interaction, but when you take a big population of dogs, it statistically comes out that anxious and impulsive dogs are more likely to start turning gray before age 4,” Grandin said.

“Genetic factors are important, but genetic factors also can be modified by experience, so you can’t just say an animal’s hard-wired genetics, it’s not. It’s both. Both genetics and the environment are important,” she said.

http://www.cnn.com/2016/12/23/health/stress-dogs-gray-hair/index.html