Posts tagged psychology

Finding shows oxytocin strengthens bad memories and can increase fear and anxiety

It turns out the love hormone oxytocin is two-faced. Oxytocin has long been known as the warm, fuzzy hormone that promotes feelings of love, social bonding and well-being. It’s even being tested as an anti-anxiety drug. But new Northwestern Medicine® research shows oxytocin also can cause emotional pain, an entirely new, darker identity for the hormone.

Oxytocin appears to be the reason stressful social situations, perhaps being bullied at school or tormented by a boss, reverberate long past the event and can trigger fear and anxiety in the future.

That’s because the hormone actually strengthens social memory in one specific region of the brain, Northwestern scientists discovered.

If a social experience is negative or stressful, the hormone activates a part of the brain that intensifies the memory. Oxytocin also increases the susceptibility to feeling fearful and anxious during stressful events going forward. 

(Presumably, oxytocin also intensifies positive social memories and, thereby, increases feelings of well being, but that research is ongoing.)

The findings are important because chronic social stress is one of the leading causes of anxiety and depression, while positive social interactions enhance emotional health. The research, which was done in mice, is particularly relevant because oxytocin currently is being tested as an anti-anxiety drug in several clinical trials.

“By understanding the oxytocin system’s dual role in triggering or reducing anxiety, depending on the social context, we can optimize oxytocin treatments that improve well-being instead of triggering negative reactions,” said Jelena Radulovic, the senior author of the study and the Dunbar Professsor of Bipolar Disease at Northwestern University Feinberg School of Medicine. The paper was published July 21 in Nature Neuroscience.

This is the first study to link oxytocin to social stress and its ability to increase anxiety and fear in response to future stress. Northwestern scientists also discovered the brain region responsible for these effects — the lateral septum – and the pathway or route oxytocin uses in this area to amplify fear and anxiety.

The scientists discovered that oxytocin strengthens negative social memory and future anxiety by triggering an important signaling molecule — ERK (extracellular signal regulated kinases) — that becomes activated for six hours after a negative social experience. ERK causes enhanced fear, Radulovic believes, by stimulating the brain’s fear pathways, many of which pass through the lateral septum. The region is involved in emotional and stress responses.

The findings surprised the researchers, who were expecting oxytocin to modulate positive emotions in memory, based on its long association with love and social bonding.

“Oxytocin is usually considered a stress-reducing agent based on decades of research,” said Yomayra Guzman, a doctoral student in Radulovic’s lab and the study’s lead author. “With this novel animal model, we showed how it enhances fear rather than reducing it and where the molecular changes are occurring in our central nervous system.’

The new research follows three recent human studies with oxytocin, all of which are beginning to offer a more complicated view of the hormone’s role in emotions.

All the new experiments were done in the lateral septum. This region has the highest oxytocin levels in the brain and has high levels of oxytocin receptors across all species from mice to humans.

“This is important because the variability of oxytocin receptors in different species is huge,” Radulovic said. “We wanted the research to be relevant for humans, too.”

Experiments with mice in the study established that 1) oxytocin is essential for strengthening the memory of negative social interactions and 2) oxytocin increases fear and anxiety in future stressful situations.

Experiment 1: Oxytocin Strengthens Bad Memories

Three groups of mice were individually placed in cages with aggressive mice and experienced social defeat, a stressful experience for them. One group was missing its oxytocin receptors, essentially the plug by which the hormone accesses brain cells. The lack of receptors means oxytocin couldn’t enter the mice’s brain cells. The second group had an increased number of receptors so their brain cells were flooded with the hormone. The third control group had a normal number of receptors.

Six hours later, the mice were returned to cages with the aggressive mice. The mice that were missing their oxytocin receptors didn’t appear to remember the aggressive mice and show any fear. Conversely, when mice with increased numbers of oxytocin receptors were reintroduced to the aggressive mice, they showed an intense fear reaction and avoided the aggressive mice.

Experiment 2: Oxytocin Increases Fear and Anxiety in Future Stress

Again, the three groups of mice were exposed to the stressful experience of social defeat in the cages of other more aggressive mice. This time, six hours after the social stress, the mice were put in a box in which they received a brief electric shock, which startles them but is not painful. Then 24 hours later, the mice were returned to the same box but did not receive a shock.

The mice missing their oxytocin receptors did not show any enhanced fear when they re-entered the box in which they received the shock. The second group, which had extra oxytocin receptors showed much greater fear in the box. The third control group exhibited an average fear response.

“This experiment shows that after a negative social experience the oxytocin triggers anxiety and fear in a new stressful situation,” Radulovic said.

(Source: northwestern.edu)

Controversy exists over what some mental health experts call “hypersexuality,” or sexual “addiction.” Namely, is it a mental disorder at all, or something else? It failed to make the cut in the recently updated Diagnostic and Statistical Manual of Mental Disorders, or DSM-5, considered the bible for diagnosing mental disorders. Yet sex addiction has been blamed for ruining relationships, lives and careers.

Now, for the first time, UCLA researchers have measured how the brain behaves in so-called hypersexual people who have problems regulating their viewing of sexual images. The study found that the brain response of these individuals to sexual images was not related in any way to the severity of their hypersexuality but was instead tied only to their level of sexual desire.

In other words, hypersexuality did not appear to explain brain differences in sexual response any more than simply having a high libido, said senior author Nicole Prause, a researcher in the department of psychiatry at the Semel Institute for Neuroscience and Human Behavior at UCLA.

"Potentially, this is an important finding," Prause said. "It is the first time scientists have studied the brain responses specifically of people who identify as having hypersexual problems."

The study appears in the current online edition of the journal Socioaffective Neuroscience and Psychology.

A diagnosis of hypersexuality or sexual addiction is typically associated with people who have sexual urges that feel out of control, who engage frequently in sexual behavior, who have suffered consequences such as divorce or economic ruin as a result of their behaviors, and who have a poor ability to reduce those behaviors.

But, said Prause and her colleagues, such symptoms are not necessarily representative of an addiction — in fact, non-pathological, high sexual desire could also explain this cluster of problems.

One way to tease out the difference is to measure the brain’s response to sexual-image stimuli in individuals who acknowledge having sexual problems. If they indeed suffer from hypersexuality, or sexual addiction, their brain response to visual sexual stimuli could be expected be higher, in much the same way that the brains of cocaine addicts have been shown to react to images of the drug in other studies.

The study involved 52 volunteers: 39 men and 13 women, ranging in age from 18 to 39, who reported having problems controlling their viewing of sexual images. They first filled out four questionnaires covering various topics, including sexual behaviors, sexual desire, sexual compulsions, and the possible negative cognitive and behavioral outcomes of sexual behavior. Participants had scores comparable to individuals seeking help for hypersexual problems.

While viewing the images, the volunteers were monitored using electroencephalography (EEG), a non-invasive technique that measures brain waves, the electrical activity generated by neurons when they communicate with each other. Specifically, the researchers measured event-related potentials, brain responses that are the direct result of a specific cognitive event.

"The volunteers were shown a set of photographs that were carefully chosen to evoke pleasant or unpleasant feelings," Prause said. "The pictures included images of dismembered bodies, people preparing food, people skiing — and, of course, sex. Some of the sexual images were romantic images, while others showed explicit intercourse between one man and one woman."

The researchers were most interested in the response of the brain about 300 milliseconds after each picture appeared, commonly called the “P300” response. This basic measure has been used in hundreds of neuroscience studies internationally, including studies of addiction and impulsivity, Prause said. The P300 response is higher when a person notices something new or especially interesting to them.

The researchers expected that P300 responses to the sexual images would correspond to a person’s sexual desire level, as shown in previous studies. But they further predicted that P300 responses would relate to measures of hypersexuality. That is, in those whose problem regulating their viewing of sexual images could be characterized as an “addiction,” the P300 reaction to sexual images could be expected to spike.

Instead, the researchers found that the P300 response was not related to hypersexual measurements at all; there were no spikes or decreases tied to the severity of participants’ hypersexuality. So while there has been much speculation about the effect of sexual addiction or hypersexuality in the brain, the study provided no evidence to support any difference, Prause said.

"The brain’s response to sexual pictures was not predicted by any of the three questionnaire measures of hypersexuality," she said. "Brain response was only related to the measure of sexual desire. In other words, hypersexuality does not appear to explain brain responses to sexual images any more than just having a high libido."

But debate continues over whether sex addiction is indeed an addiction. A study published in 2012 by Prause’s colleague Rory Reid, a UCLA assistant professor of psychiatry, supported the reliability of the proposed DSM-5 diagnostic criteria for hypersexual disorder. However, Prause notes, that study was not focused on the validity of sex addiction or impulsivity, and did not use any biophysiological data in the analysis.

"If our study can be replicated," she said, "these findings would represent a major challenge to existing theories of a sex ‘addiction.’ "

(Source: newsroom.ucla.edu)

The so-called trust hormone, oxytocin, may not improve the symptoms of children with autism, a large study led by UNSW researchers has found.

Professor Mark Dadds, of the UNSW School of Psychology, says previous research suggested that oxytocin – a hormone with powerful effects on brain activity linked to the formation of social bonds – could have benefits for children with the disorder.

“Many parents of children with autism are already obtaining and using oxytocin nasal spray with their child, and clinical trials of the spray’s effects are underway all over the world. Oxytocin has been touted as a possible new treatment, but its effects may be limited,” Professor Dadds says.

Autism is a complex condition of unknown cause in which children exhibit reduced interest in other people, impaired social communication skills and repetitive behaviours.

To determine its suitability as a general treatment Professor Dadds’ team conducted a randomised controlled clinical trial of 38 boys aged between seven and 16 years of age with autism. Half were given a nasal spray of oxytocin on four consecutive days.

The study has been accepted for publication in the Journal of Autism and Developmental Disorders.

“We found that, compared to a placebo, oxytocin did not significantly improve emotion recognition, social interaction skills, repetitive behaviours, or general behavioural adjustment,” says Professor Dadds.

“This is in contrast to a handful of previous smaller studies which have shown some positive effects on repetitive behaviours, social memory and emotion processing.

“These studies, however, were limited by having small numbers of participants and/or by looking at the effects of single doses of oxytocin on specific behaviours or cognitive effects while the participants had the oxytocin in their system.

“The results of our much larger study suggest caution should be exercised in recommending nasal oxytocin as a general treatment for young people with autism.”

The boys in the new study were assessed twice before treatment, three times during the treatment week, immediately afterwards and three months later, with a parent present. Factors such as eye contact with the parent, responsiveness, warmth, speech, positive body language, repetitive behaviours, and recognition of facial emotions were observed.

Research in people who are healthy shows oxytocin can increase levels of trust and eye-gazing and improve their identification of emotions in others.

One likely possibility is that many children with autism have impaired oxytocin receptor systems that do not respond properly, Professor Dadds says. But there may be a subgroup of children for whom oxytocin could be beneficial, and research is needed to determine who responds to it and how best to deliver it.

(Source: newsroom.unsw.edu.au)

The information carried by the electrical activity of neurons is a mixture of stored memories, environmental circumstances, and current state of mind, scientists have found in a study of laboratory rats. The findings, which appear in the journal PLoS Biology, offer new insights into the neurobiological processes that give rise to knowledge and memory recall.

The study was conducted by Eduard Kelemen, a former graduate student and post-doctoral associate at the State University of New York (SUNY) Downstate Medical Center, and André Fenton, a professor at New York University’s Center for Neural Science and Downstate Medical Center. Kelemen is currently a postdoctoral fellow at University of Tuebingen in Germany.

The idea that recollection is not merely a replay of our stored experiences dates back to Plato. He believed that memory retrieval was, in fact, a much more intricate process—a view commonly accepted by today’s cognitive psychologists and couched in the theory of constructive recollection. The theory posits that during memory retrieval, information across different experiences may combine during recall to form a single experience. Such a process may explain the prevalence of false memories. For example, studies have shown that people mistakenly recalled seeing a school bus in a movie if the bus was mentioned after they watched the movie.

In addition, other scholarship has shown that a subject’s mindset can also influence the retrieved information. For example, looking at a house from the perspective of a homebuyer or a burglar leads to different recollections—potential purchasers may recall the house’s leaky roof while would-be burglars may remember where the jewelry is kept.

But while the psychological contours of retrieval are well-documented, very little is known about the neural activity that underlies this process.

With this in mind, Fenton and Kelemen centered their study on the neurophysiological processes rats employ as they solve problems that require memory retrieval. To do so, they employed techniques developed during the last two decades. These involve monitoring the electrical activity of neurons in the rats’ hippocampus—the part of the brain used to encode new memories and retrieve old ones. By spotting certain types of neuronal activity, researchers have historically been able to perform what amounts to a mind reading exercise to decode what the rat is thinking and even comprehend the specifics of the rats’ memory retrieval.

In their experiments, Fenton and Kelemen tested the viability of a concept, “cross-episode retrieval”— stimulating the brain activity in a given circumstance that was also activated in a previous, distinctive experience.

“Such cross-episode expression of past activity can create opportunities for generating novel associations and new information that was never directly experienced,” the authors wrote.

To test their hypotheses, rats were placed in a stable, circular arena, then in a rotating, circular arena of the same size, followed by a return to the stable arena. In the rotating arena condition, the surface turned slowly, making it necessary for the rat to think about its location either in terms of the rotating floor or in terms of the stationary room.

Overall, the results showed district neural activity between the stable and rotating conditions. However, during the rotating task, the researchers intermittently observed “cross-episode retrieval”—that is, at times, neurons expressed patterns of electrical activity under the rotating-arena condition that were similar to those activity patterns that were used in the stable-arena condition. Notably, cross-episode retrieval occurred more frequently when the angular position of the rotating arena was about to complete a full rotation and return to the same position as in the stable condition, demonstrating that retrieval is influenced by the environment.

To show that cross-episode retrieval was influenced by current state of mind, Fenton and Kelemen took advantage of an earlier finding from their experiments: during the arena rotation, neural activity switches between signaling the rat’s location in the stationary room and the rat’s location on the rotating arena floor. Cross-episode retrieval was also more likely when neuronal activity represented the position of the rat in the stationary room than when it represented positions that rotate with the arena. This showed that retrieval is influenced by internal cognitive variables that are encoded by hippocampal discharge—i.e., a state of mind.

“These experiments demonstrate novel, key features of constructive human episodic memory in rat hippocampal discharge,” explained Fenton, “and suggest a neurobiological mechanism for how experiences of different events that are separate in time can nonetheless comingle and recombine in the mind to generate new information that can sometimes amount to valuable, creative insight and knowledge.”

(Source: nyu.edu)

We take it for granted that our thoughts are in constant turnover. Metaphors like “stream of consciousness” and “train of thought” imply steady, continuous motion. But is there a mechanism inside our heads that drives this? Is there something compelling our attention to move on to new ideas instead of dwelling in the same spot forever?

A research team led by Dr Matthew Johnson in the School of Psychology at The University of Nottingham Malaysia Campus (UNMC) may have discovered part of the answer. They have pinpointed an effect that makes people turn their attention to something new rather than dwelling on their most recent thoughts. The research, which has been published in the academic journal Psychological Science, could have implications for studying disorders like autism and ADHD.

Dr Johnson said: “We have discovered a very promising paradigm. The effect is strong and replicates easily – you could demonstrate it in any psychology lab in the world. The work is still in its early stages but I think this could turn out to be a very important part of our understanding of how and why our thoughts work the way they do.

The paper “Foraging for Thought: An Inhibition-of-Return-Like Effect Resulting From Directing Attention Within Working Memory” sheds new light on what makes us turn our attention to things we haven’t recently thought rather than ones we have. It was carried out in collaboration with Yale University, Princeton University, The Ohio State University, and Manhattanville College.

The “inhibition of return” effect is well-established in visual attention. At certain time scales, people are slower to turn their thoughts back to a location they have just paid attention to. They are much quicker to focus on a new location. Some have interpreted this effect as a “foraging facilitator,” a process that encourages organisms to visit new locations over previously visited ones when exploring a new environment or performing a visual search.

However, in this new study, the researchers weren’t focusing on visual search, but on the process of thought itself. Participants were shown either two words or two pictures, and when the items disappeared, they were instructed to turn their attention briefly to one of the items they were just shown and ignore the other. Immediately afterwards they were asked to identify either the item they had just thought about, or the one they had ignored. For both pictures and words the participants were quicker to react to the item they had ignored.

Dr Johnson said: “The effect was shocking. When we began we expected to find the exact opposite – that thinking about something will make it easier to identify. We were initially disappointed – but when the effect was replicated over multiple experiments we realised we were onto something new and exciting.”

Critically, the effect is temporary; on a later memory test participants remembered attended items better than ignored ones.

Dr Johnson said: “That’s important. If thinking about things made us worse at remembering them long-term, it would make no sense for real-world survival. That’s why we think we’ve tapped into something fundamental about how we think in the moment – a possible mechanism keeping our thoughts moving onto new things, and not getting stuck.”

The researchers have more experiments planned to explore this effect. They say the new task could have implications for studying disorders like autism and ADHD, where attention may persist too long or move on too easily, as well as conditions with more general cognitive impairments, such as schizophrenia and ageing-related dementia.

Future studies planned also include applying cognitive neuroscience techniques to determine the effect’s underlying neural foundations.

(Source: nottingham.ac.uk)

Ninety-somethings seem to be getting smarter. Today’s oldest people are surviving longer, and thankfully appear to have sharper minds than the people reaching their 90s 10 years ago.

Kaare Christensen, head of the Danish Aging Research Center at the University of Southern Denmark in Odense, and colleagues found Danish people born in 1915 were about a third more likely to live to their 90s than those born in 1905, and were smarter too.

During research, which spanned 12 years and involved more than 5000 people, the team gave nonagenarians born in 1905 and 1915 a standard test called a “mini-mental state examination”, and cognitive tests designed to pick up age-related changes. Not only did those born in 1915 do better at both sets of tests, more of them also scored top marks in the mini-mental state exam.

It’s a landmark study, says Marcel Olde Rikkert, head of the Alzheimer’s centre at Radboud University Nijmegen Medical Centre in the Netherlands. It is scientifically rigorous, it invited all over 90-year-olds in Denmark to participate, and it also overturns our ingrained views of old age, he says.

Getting better all the time

"The outcome underlines that ageing is malleable," Olde Rikkert says, adding that cognitive function can actually be a lot better than people would assume until a very high age.

"It’s motivating that people, their lifestyles, and their environments can contribute a lot to the way they age," he says, though he cautions that not everything is in our own hands and help is still needed for those with dementia or those who do experience cognitive decline as they age.

Improved education played a part in the changes, says Christensen. But the study does not disentangle the individual effects of the numerous things that could be responsible for the improvements. “The 1915 cohort had a number of factors on their side – they experienced better living and working conditions, they had radio, TV and newspapers earlier in their lives than those born 10 years before,” he says.

Tellingly, there was no difference in the physical test results between the two groups. The authors say this “suggests changes in the intellectual environment rather than in the physical environment are the basis for the improvement”.

(Source: newscientist.com)