Behaviour neurologist explains how our brains feel emotion

Interview with behaviour neurologist, Antonio Damasio on how our brains feel emotion.

"An emotion consists of a very well orchestrated set of alterations in the body. Its purpose is to make life more survivable by taking care of a danger or taking advantage of an opportunity."

Question: What is happening in our brain when we feel an emotion?

Antonio Damasio: Feeling of an emotion is a process that is distinct from having the emotion in the first place. So it helps to understand what is an emotion, what is a feeling, we need to understand what is an emotion. And the emotion is the execution of a very complex program of actions. Some actions that are actually movements, like movement that you can do, change your face for example, in fear, or movements that are internal, that happen in your heart or in your gut, and movements that are actually not muscular movements, but rather, releases of molecules. Say, for example, in the endocrine system into the blood stream, but it’s movement and action in the broad sense of the term.

And an emotion consists of a very well orchestrated set of alterations in the body that has, as a general purpose, making life more survivable by taking care of a danger, of taking care of an opportunity, either/or, or something in between. And it’s something that is set in our genome and that we all have with a certain programmed nature that is modified by our experience so individually we have variations on the pattern. But in essence, your emotion of joy and mine are going to be extremely similar. We may express them physically slightly differently, and it’s of course graded depending on the circumstance, but the essence of the process is going to be the same, unless one of us is not quite well put together and is missing something, otherwise it’s going to be the same.

And it’s going to be the same across even other species. You know, there’s a, you know, we may smile and the dog may wag the tail, but in essence, we have a set program and those programs are similar across individuals in the species.

Then the feeling is actually a portrayal of what is going on in the organs when you are having an emotion. So it’s really the next thing that happens. If you have just an emotion, you would not necessarily feel it. To feel an emotion, you need to represent in the brain in structures that are actually different from the structures that lead to the emotion, what is going on in the organs when you’re having the emotion. So, you can define it very simply as the process of perceiving what is going on in the organs when you are in the throws of an emotion, and that is achieved by a collection of structures, some of which are in the brain stem, and some of which are in the cerebral cortex, namely the insular cortex, which I like to mention not because I think it’s the most important, it’s not. I actually don’t think it’s the number one structure controlling our feelings, but I like to mention because it’s something that people didn’t really know about and many years ago, which probably now are going close to 20 years ago, I thought that the insular would be an important platform for feelings, that’s where I started. And it was a hypothesis and it turns out that the hypothesis is perfectly correct. And 10 years ago, we had the first experiments that showed that it was indeed so, and since then, countless studies have shown that when you’re having feelings of an emotion or feelings of a variety of other things, the insular is active, but it doesn’t mean that it’s the only thing that is active and there are other structures that are very important as well.

Recorded July 2, 2010
Interviewed by David Hirschman

About the anti-anxiety benefits of yoga

Strike a Pose to Reduce Anxiety

By Jennifer Gibson, PharmD, practicing clinical pharmacist and freelance medical writer.

Source: BrainBlogger, a biomedical blog that covers topics from multidimensional biopsychosocial perspectives.

Yoga is a practice almost as old as time itself. It combines mental and physical elements that people today use to enhance spirituality, exercise, decrease stress, and increase well-being. While many practitioners of yoga seem almost mystical and more philosophical than the average bear, a new study proves that you need not be a yogi to achieve the anti-anxiety benefits of yoga.

Research published in the Journal of Alternative and Complementary Medicine reports that practicing yoga postures increased the levels of gamma-aminobutyric acid (GABA) in the brain. (GABA is a neurotransmitter in the central nervous system that is responsible for reduced anxiety, increased relaxation, and enhanced muscle tone.) In this study, healthy subjects with no significant physical or psychiatric illnesses or conditions participated in 60-minute yoga sessions 3 times weekly for 12 weeks. Alternatively, a comparison group participated in a metabolically matched walking program for the same length of time. Subjective mood and anxiety measurements were recorded, and magnetic resonance spectroscopy scans were completed at baseline and at 12 weeks.

Overall, yoga participants experienced greater improvement in mood and decrease in anxiety, compared to the walking group. More objectively, yoga participants showed increased levels of GABA in the brain. Positive correlations were observed between improved mood and decreased anxiety and GABA levels. This appears to be the first time that long-term behavioral interventions have produced increased GABA levels. (A similar pilot study showed that a single yoga session increased GABA levels.) Pharmacological agents are frequently used to increase GABA activity in order to reduce anxiety and improve mood. Yoga, in contrast to pharmacological agents, carries almost no risk of adverse consequences and costs very little, if anything, to practice.

In addition to decreasing anxiety, yoga and other mindfulness-based techniques improve stress, depression, overall well-being, neuroticism, eating habits, energy levels, and pain. Yoga has been prescribed for arthritis and other joint and muscle disorders, with strikingly positive benefits. Yoga also promotes immune function, weight loss, decreased heart rate and blood pressure, and muscle strength. Yoga has even been shown to decrease premature delivery when practiced by women during pregnancy. While other forms of exercise bring about the same benefits, yoga has shown more robust benefits than other activities.

With seemingly all the benefits and none of the risks, yoga should be explored as part of a treatment plan for individuals with mood and anxiety disorders. Or, for anyone wishing to improve well-being. So, grab a yoga mat and strike a pose. Namaste.

References

• Field T (2011). Yoga clinical research review. Complementary therapies in clinical practice, 17 (1), 1-8 PMID: 21168106
• Haaz S, & Bartlett SJ (2011). Yoga for arthritis: a scoping review. Rheumatic diseases clinics of North America, 37 (1), 33-46 PMID: 21220084
• Smith BW, Shelley BM, Dalen J, Wiggins K, Tooley E, & Bernard J (2008). A pilot study comparing the effects of mindfulness-based and cognitive-behavioral stress reduction. Journal of alternative and complementary medicine (New York, N.Y.), 14 (3), 251-8 PMID: 18370583
• Streeter CC, Jensen JE, Perlmutter RM, et al. Yoga Asana sessions increase brain GABA levels: a pilot study. J Altern Complement Med. May 2007;13(4):419-426. PMID: 17532734
• Streeter CC, Whitfield TH, Owen L, Rein T, Karri SK, Yakhkind A, Perlmutter R, Prescot A, Renshaw PF, Ciraulo DA, & Jensen JE (2010). Effects of yoga versus walking on mood, anxiety, and brain GABA levels: a randomized controlled MRS study. Journal of alternative and complementary medicine (New York, N.Y.), 16(11), 1145-52 PMID: 20722471

Somatic markers - how the body affects the mind

Your somatic markers know when to hold ‘em

By Lorimer Moseley in Body In Mind:Research into the role of the brain and mind in chronic pain, 21 March 2011

There is a very large body of data that show that the body affects the mind. That is, bodily processes and responses to stimuli affect our thoughts about those stimuli and our behavioural responses to them. Some of the most intriguing research in this area has been done by Antonio Damasio – most famously the Iowa gambling project [1]. They have primarily investigated people who have damage to their emotional system – ventromedial prefrontal cortex - yet seem to function very well on language and intelligence tests. They do, however, act in a socially inappropriate manner and make stunning judgement errors. One of the earliest studies showed that while healthy volunteers began to choose advantageously before they worked out which strategy was in fact advantageous, patients with damage to their prefrontal lobe chose disadvantageously the whole time – even if they had worked out which strategy was in fact advantageous. The study also showed that normals would have a galvanic skin response, a sign of sympathetic activation, before they realised they were about to make a risky choice. Damasio’s group has done a bunch of studies that underpin their Somatic Marker Hypothesis – “Somatic markers are events or chemicals in your body, detection of which evokes particular feelings or emotions. A note here that, according to Damasio – check out his very readable book ‘The feeling of what happens’, emotions are brain representations of body states. That is, you see a scary looking man approaching you, your sympathetic nervous system is activated, this sends feedback to your brain and your brain registers this feedback and you feel frightened). So, the essence of the somatic marker hypothesis is that when a “negative somatic marker is linked to a particular future outcome it becomes an alarm bell and when a positive somatic marker is linked to a particular future outcome it becomes an incentive” [2].

So, people who have damage to the part of the brain that registers feedback from the somatic markers, don’t ‘read the signals’ from their internal environment. The somatic marker hypothesis argues that this is why they make errors of judgement and do socially inappropriate things – they can’t process the shift in the somatic markers. So, next time you join the poker game, remember what the somatic marker hypothesis says: it is your body that tells you when to hold ‘em, when to fold ‘em, when to walk away and when to run, not Kenny Rogers. So, clearly there is bottom-up influence on cognition – the embodied cognition people talk about this a great deal. We have shown (see here for BiM discussion on ‘Rubber Hand makes your real hand go colder‘ and visual distortion) a top-down effect of cognitive representations on the body [3, 4]. The next blog will raise the stakes even further, albeit rather speculatively…..

1. Bechara, A. (1997). Deciding Advantageously Before Knowing the Advantageous Strategy Science, 275 (5304), 1293-1295 DOI:10.1126/science.275.5304.1293

2. Damasio AR (1996). The somatic marker hypothesis and the possible functions of the prefrontal cortex. Philosophical transactions of the Royal Society of London. Series B, Biological sciences, 351 (1346), 1413-20 PMID: 8941953

3. Moseley, G., Olthof, N., Venema, A., Don, S., Wijers, M., Gallace, A., & Spence, C. (2008). Psychologically induced cooling of a specific body part caused by the illusory ownership of an artificial counterpart Proceedings of the National Academy of Sciences, 105 (35), 13169-13173 DOI: 10.1073/pnas.0803768105

4. Moseley, G., Parsons, T., & Spence, C. (2008). Visual distortion of a limb modulates the pain and swelling evoked by movement Current Biology, 18 (22) DOI:10.1016/j.cub.2008.09.031

On chronic pain and body schema

Pain: The Science and Culture of Why We Hurt

by Marni Jackson

"Why do we still distinguish between mental pain and physical pain," she asks, "when pain is always an emotional experience? Why is pain so poorly understood, especially in a century of self-scrutiny? Hasn't anyone noticed the embarrassing fact that science is about to clone a human being but still can't cure the pain of a bad back?"

A new take on the Gate Control Theory, or, The benefits of rubbing your boo-boos

from the blog of Dave Walton, physiotherapist and Assistant Professor with the School of Physical Therapy at University of Western Ontario.

" ... (I)t is conceivable that the brain's sentry body-self neuromatrix maintains that heightened state of arousal and sensitivity in it's efforts to obtain knowledge about the state of the painful part. This might also be the mechanism behind Peter O'Sullivan's observations that some people with chronic low back pain exhibit behaviours that result in further pain (ie. it's painful to extend the lumbar spine, but some people habitually adopt this posture despite the pain). In that case, this theory would suggest that any stimuli coming from the area, even if unpleasant, can offer at least some form of relief to a neuromatrix seeking information, especially in those conditions that you can't see. Not saying this is good, just saying it makes sense in light of my pseudo-theory. Note that this theory would also support the notion that manual therapies probably have much of their effect through drawing attention to, and providing neurophysiological stimulus from, painful parts of the body. The focus on identifying very specific movement impairments (ie. restricted superior glides of the facet) becomes less of a priority than does identifying the amount of stimulus that can be applied to a body in pain that provides adequate stimuli without being perceived as threatening to the sensitized 'pain' system."

I can't find it! Distorted body image and tactile dysfunction in patients with chronic back pain

By G. Lorimer Moseley

ABSTRACT: The conscious sense of our body, or body image, is often taken for granted, but it is disrupted in many clinical states including complex regional pain syndrome and phantom limb pain. Is the same true for chronic back pain? Body image was assessed, via participant drawings, in six patients with chronic back pain and ten healthy controls. Tactile threshold and two-point discrimination threshold (TPD) were assessed in detail. All the patients, and none of the controls, showed disrupted body image of the back. Five patients were unable to clearly delineate the outline of their trunk and stated that they could not “find it”. TPD was greatly increased in the same zone as the absence or disruption of body image, but was otherwise similar to controls. The disturbance of body image and decrease in tactile acuity coincided with the normal distribution of pain, although there was no allodynia and there was no relationship between resting pain level and TPD. Tactile threshold was unremarkable for patients and controls. These preliminary data indicate that body image is disrupted, and tactile acuity is decreased, in the area of usual pain, in patients with chronic back pain. This finding raises the possibility that training body image or tactile acuity may help patients in chronic spinal pain, as it has been shown to do in patients with complex regional pain syndrome or phantom limb pain.

Ruled by the Body: How Physical Illness Affects the Brain

'Many common ailments and physical conditions can influence the brain, leaving you depressed, anxious or slow-witted.' says Erich Kasten,professor of medical psychology at the University of Lbeck in Germany in an article that appeared in Scientific American on March 3, 2011.

According to Kasten, doctors often forget to ask patients about psychological symptoms. Conversely, psychologists and psychiatrists may treat mental troubles in isolation without looking for a physical cause. But now some doctors and psychologists are reviving the decades-old discipline of somatopsychology, which centers on the effects of physical illness on the brain.

'In Western culture people have long treated body and mind as separate. This dichotomy, popularized by French philosopher René Descartes in the 17th century, is still reflected in medical practice, as the specialists who look after our bodies remain different from those who attend to our psyches. Of course, the division has blurred in recent decades. We now know, after all, that the mind is housed in a physical entity, the brain, which is part of the body. And most people are also aware that psychological problems can produce physical symptoms in the form of psychosomatics; for instance, mental stress can spawn headaches, an upset stomach or even heart problems.

'But fewer people appreciate that the influence also runs in the other direction—that changes in your body can profoundly perturb your mental state,' he says.

Full article available at Scientific American website

How neural rhythm processing shapes the way we communicate

Sonja Kotz leads the Minerva research group "Neurocognition of Rhythm in Communication" at the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig. She presented evidence from neuroimaging on the impact of cognitive functions on bilingual processing at the AAAS symposium "Crossing Borders in Language Science: What Bilinguals Tell Us About Mind and Brain".

Rhythm, as the recurrent patterning of events in time, underlies most human behavior such as speech, music, and body movements. Sonja Kotz investigates how temporal patterns in di!erent languages influence the processing of phonological, semantic, and syntactic information. Individuals who learn a new language usually need time to develop a "feel" for its characteristics. With rapid speech it can initially even be difficult to recognize individual words. "This is because the brain has to become accustomed to new speech rhythms," explains Sonja Kotz.

Our brain is very good at recognizing patterns in the environment and uses them to create general predictions about the near future.

"We assume there is a neural network permanently engaged in evaluating information about duration, rhythm, tempo and stress of syllables in order to recognize temporal regularities in the stream of speech", says Kotz. During language acquisition, this network could store fundamental regularities of speech in the brain so that later, language processing is more efficient.

Rhythm processing predominantly occurs in brain areas in and just belowthe cerebral cortex but also in motor areas and evolutionarily older areas like the cerebellum and basal ganglia.

"This points to an early stage of development," says Kotz. "The evolution of language would not have been possible without the development of brain areas which have the ability to structure events temporally." To meet the high communicative demands of homo sapiens, the motor system in and below the cerebral cortex might have become increasingly sensitive to rhythmic input.

Source:
Sonja A. Kotz, Max-Planck-Gesellschaft

Medical News Today

Stressed out! The powerful biology of stress - ABC Radio National – All In The Mind

ABC Radio National – All In The Mind

Stressed out! The powerful biology of stress

Presenter: Natasha Mitchell Producer: Natasha Mitchell/Anita Barraud

A little tension keeps us on our toes - we're biologically primed for it. But 'toxic' stress makes us physically sick, and powerful research is now revealing its potent impact on our developing bodies and brains. Don't miss two world leaders transforming our understanding.

Natasha Mitchell: And a happy new year on ABC Radio National Summer. Hope it's a fabulous 2011 for you and your kin, without the burden of stress. Although, let's admit it - stress is a fact of life. [Stress-news montage...]: The so called subprime mortgage crisis has sent world stock markets into a spin ... Domestic violence is on the rise, depression is on the rise, anxiety is on the rise, alcohol and drug use are on the rise, so the stress is starting to take its toll ... Tonight the biggest mortgage meltdown ... The thing that makes people most stressed out is when they don't feel like they have any control.

Bruce McEwen: The medical community has begun to accept the notion that for cardiovascular disease, for depression, for certain disorders, that there is a very clear inescapable link with stress. We're increasingly aware of the important role that inflammation plays. Inflammation is part of everything from cancer to Alzheimer's disease, to arthritis, to diabetes, to cardiovascular disease. you name it. And psychological stress elevates the inflammatory cytokines, just as an overload of calories, just as you know many of these things.

Tom Boyce: There is a kind of biological embedding if you will, a biological fingerprint that is left by experiences of growing up in disadvantage, and there are both short term changes in the biology of children who are exposed to those kinds of settings, but there appears to be longer term changes as well. They affect their development and may potentially affect things as distant as when they die, the chronic diseases they develop over the course of their adult life, that their mental health over the years of their adult life.

Natasha Mitchell: So is there a biology of misfortune? More on that provocative proposal later. We're talking stress, the all-pervasive feeling of worry, of burden, of overload and uncertainty. And crucially, of loss of control.
Last year the New York Times reported of three men, all in relatively good health, having heart attacks within weeks of being laid off from the steel mills in New York. 'I think the stress just got to him,' said Kim Smith of her 42-year-old husband Bob. Well today on the show - be blown away by what science is revealing about stress in the body and brain, in children, and in all of us. This is All in the Mind and I'm Natasha Mitchell.

Tom Boyce: I think of it as being almost kind of like an archaeological dig, if you will, you begin with the lived experience of the child, the adversity and stressful events that that child encounters, that is experienced by the child within circuitry of the brain. So we begin this archaeology by exploring what are the brain structures and functions that are changed by early exposure. Then you dig down a little further, a little smaller in scale and complexity and there are differences in the cellular level. in the communication between neurons within the brain, the kind of neuro-transmitter systems that are present in the brain. And then a little deeper are the sub-cellular kinds of processes like the epigenetic changes that we are now seeing that are also systematically different between low and high disadvantaged children.

Natasha Mitchell: And by epigenetic you are referring to not the genetics of a person but the cellular architecture that influences which genes are switched on and off in a body, which is very much affected, as we are finding out, by our environment, by what we are exposed to—our parenting, what we eat.

Tom Boyce: Exactly. The metaphor that I like to think about in this regard is when we move we pack all of our stuff in boxes, right? And boxes are great for moving from one place to another, but they're not very good for actually using the stuff that's in them. So we have to unpack these boxes of genes in order to use the genes, to express them, to have them guide the development of proteins that they code for. And epigenetics is this business of the packaging of the genome and the way in which it influences the expression of genes in a differential manner.

Natasha Mitchell: Paediatrician Professor Tom Boyce. And both my guests today think it's time policy makers took notice of biological evidence in their planning. First to the man whose research has really defined the study of stress. Professor Bruce McEwen from Rockefeller University is a neuroscientist and a neuro-endocrinologist. Well Bruce, welcome to the program.

Bruce McEwen: Thank you very much, it's good to be talking with you.

Natasha Mitchell: Stress operates paradoxically, doesn't it? In the one sense a modicum of stress keeps us on our toes; too much is a problem. I mean the brain reacts to stress but it also adapts to stress, doesn't it? Tell us about that paradox.

Bruce McEwen: Well I think the best way to start is to talk about the different ways we think of stress. There is positive stress when you rise to a challenge and generally are exhilarated because you are able to meet that challenge. And it means you have to have a good sense of yourself, a good sense of whether the risk is worth taking, good self-esteem and a good sense of control. And then there's tolerable stress, something really bad happens, say the loss of a job, a divorce, the loss of a loved one, but you have these internal resources and you have a social support system that can help you out. so you can weather the storm.
And then there's toxic stress—there you don't have the personal resources perhaps, you don't have the social support system and the favourite definition of stress is really something where you don't have control. And then the paradox about the body is that the body produces chemicals, hormones, like cortisol and adrenalin and we also produce inflammatory cytokines when we're stressed, it affects our metabolic hormones.

Natasha Mitchell: And those cytokines are key immune cells.

Bruce McEwen: Immune cells. but they are also produced by many other cells of the body and the brain and they are sort of really hormones in a way. The autonomic nervous system, our sympathetic and our parasympathetic systems, they help keep our heart rate balanced and also affect inflammatory processes, they affect metabolic processes. So there's this whole network of what we call 'allostasis', which is the active process by which the body adapts to a challenge, a stressful situation. The paradox is that when these chemicals are overproduced or under-produced, when this network is out of sync, then the body can show a wear and tear that we call 'allostatic load', it really is the price the body pays. Normally the adaptive response is 'turn it on' and 'turn it off'. If you can't turn it off or if you can't turn it on in sufficient amounts you have problems. and that's what leads over time to an accumulation of wear and tear that contributes to all of the diseases of modern life, whether it's obesity, diabetes, cardiovascular disease, arthritis, and even some of the degenerative brain diseases like Alzheimer's disease and so forth, are really products of this and are made worse by this imbalance.

Natasha Mitchell: And it was indeed Bruce McEwen who nearly 20 years ago now defined the concept of 'allostatic load' to describe this imbalance when the body's stress system, our classic fight or flight response, doesn't switch off. And you can imagine those situations, a boss constantly on your back, an angry relationship, a child growing up in a deprived home. And Tom Boyce is especially interested in this last scenario. As Professor of Paediatrics and Interdisciplinary Studies at the University of British Columbia in Vancouver, where he holds the BC Leadership Chair in Child Development. He and colleagues are doing some extraordinary work tracking stress hormones in kindy kids.

Tom Boyce: So there are two major stress response systems at the neuroendocrine level in the body. One is what we call the HPA axis which stands for the hypothalamic pituitary adrenal cortical axis, which outputs from the adrenal gland that sits on top of the kidney, cortisol. And cortisol has profound effects on the immune system, the cardiovascular system, the peripheral vasculature, the amount of glucose that's in the blood and so on. The second system is called the locus coeruleus norepinephrine system.

Natasha Mitchell: Say that fast after you've had a glass of wine.

Tom Boyce: Really... And it begins with this little nucleus that's in the brain stem and it's responsible for activating the autonomic nervous system which is the part of human biology that mediates the whole fight or flight response. The dry mouth, dilatation of the pupils in the eye, the sweaty palms and so on.

Natasha Mitchell: The beating heart, the sweating brow...

Tom Boyce: That's right, all of the things that we're all familiar with right. What we're finding in our work in the San Francisco bay area among kindergarten children is that kids who within their social groups are more subordinate, who kind of filter to the bottom of the social hierarchy within the group of children within their class, that they have higher levels of reactivity in both of those systems than do children who are dominant and at the top, the leadership, if you will, of the classroom. We think that a similar kind of thing happens among children of low social class families. A variety of work has shown that kids who are growing up in disadvantaged families have higher cortisol levels, higher cortisol reactivity, changes in immune system, that are greater among kids in disadvantage.

Natasha Mitchell: Just play that out a bit further, what does it mean to be subordinate in a kindy context, the kindergarten context? You've done some very interesting observational studies. haven't you. and then measuring cortisol levels in the saliva of those little kids. but what does it mean to be subordinate in a kindy hierarchy?

Tom Boyce: Any kindergarten teacher can tell you that within two weeks of 20 kids coming together in a classroom there will be a pecking order that is linear and transitive, with kids at the top and kids at the bottom. There are children who imitate each other, who defer to one child versus another, who automatically get to go to the head of the line instead of the back of the line. And this is something, if you think about it, we're all basically familiar with, not only from our adult experiences but from our childhood experiences. And it turns out that this ranking of children has certain things in common with the ranking that occurs within societies. And so we've been doing observational studies looking to see whether there are differences in things like stress reactivity, if there are differences in sort of pre-clinical psychiatric conditions, behaviour problems and differences in physical health problems as well. But there are other investigators: Sonia Lupien at McGill University is an example and this is Bruce McEwen's work as well showing that even basal levels of salivary cortisol are higher among kids who are from lower SES families. There may be changes over time and kids may sort themselves out in different ways as they go into adolescence and into young adulthood, but we think that there is a tendency at least at the group level for kids who start out high in HPA reactivity and basal secretion to stay there.

Natasha Mitchell: Now this is very significant because it has all sorts of effects down the track doesn't it? Tell us about the dental caries study that you did.

Tom Boyce: We realised at some point in our study of kindergarten children that one of the effects of cortisol over the longer term, when it's constantly secreted high such as in adults with Cushing's syndrome is that it causes a depletion of calcium in calcified tissues like bones. People with Cushing's disease get osteopenea and osteoporosis. We weren't going to study the bones of these kindergarten children because they are presumably all fine but we did realise within the next year they were all going to have teeth falling out, which is another calcified tissue.

Natasha Mitchell: You became the tooth fairy.

Tom Boyce: It was called the tooth fairy project, and we paid kids $10 a tooth, by the way as a little aside I think we paid them bit too much because when one of the teeth came back from the dental school and they said this is not a human tooth, this is a dog's tooth, so somewhere in Berkeley there's a dog missing a tooth. And we have in fact found that the kids who were more reactive in the HPA axis in fact had thinner and less dense enamel within the teeth that had been exfoliated. So we think that that may be part of the key as to why subordinate kids get more caries is because they have greater cortisol secretion and this comes out in the saliva and may change the enamel density and thickness.

Natasha Mitchell: And as we've heard higher resting levels of cortisol are also linked with elevated markers of inflammatory processes in the body which Tom Boyce says have also been recorded in disadvantaged kids and which point towards higher rates of cardiovascular disease, chronic pulmonary disease and mood disorders in adulthood.

This is All in the Mind on ABC Radio National abc.net.au/rn going global on Radio Australia and as podcast. I'm Natasha Mitchell. What about the brain? Bruce McEwen argues it's been neglected as the organ of stress and his work is revealing how significantly it can be remodelled. You'll remember leading neuroscientist Fred Gage on the show talking about our plastic organ of memory called the hippocampus deep inside the brain. Turns out it's very receptive to cortisol, in fact the stress hormone helps us remember better. But too much of a good thing, and in rats at least ……….

Bruce McEwen: We found that certain neurons in the hippocampus when under chronic stress their dendrites, these big trees that are the receiving points for information from other nerve cells, they shrink.

Natasha Mitchell: They're like around every brain cell there are these sort of sprouting limbs if you like and dendrites are what bring the signals in and some people would have heard that axons are what take the signals out. So what happens to those branching dendritic structures?

Bruce McEwen: In the hippocampus they shrink, and there are fewer connections. But then a colleague in India, Shona Chattarji, discovered that under the very same conditions of stress neurons in the amygdala were actually growing and forming new connections—which is an organ of fear and if it's overactive of anxiety—and the animal is becoming more anxious. Now there's another brain area called the prefrontal cortex.
Natasha Mitchell: Which is at the front of our brain, it's our executive brain in many senses, it helps us plan and prioritise that sort of thing.

Bruce McEwen: And it also governs our emotions, it keeps the amygdala in check and it helps to decide, along with the hippocampus which is very important for remembering where you are, the context of what is happening, it helps to decide whether these situations are worth paying attention to and it keeps the system from overreacting. And then with our collaborator John Morrison we discovered that there's a part of the prefrontal cortex in which these neurons are shrinking, the dendrites are shrinking and they're losing connections. So they are losing a very important input—it's a reversible process, if you stop the stress it will grow back.

Natasha Mitchell: Now what does that mean, what impact does that have on a person's behaviour or in this case a rat's behaviour?

Bruce McEwen: Well what we found is when the animal, the rat, is challenged with a complex task in which it has to shift the meaning of cues that predict where a food reward is, if the task is difficult, having either a lesion of the prefrontal cortex which other people did, or chronic stress, reduces mental flexibility. Their ability to shift is not totally gone, it's just much slower and less efficient.

Natasha Mitchell: It sort of makes sense of there are fewer dendritic arms receiving signals, those cells aren't as receptive to the signals that they receive, I guess.

Bruce McEwen: And then if we talk about translation, the graduate student who did this work Connor Liston, is also a medical student. He studied some of his fellow medical students studying for the board exam, the big exam.
Natasha Mitchell: A very stressful situation.

Bruce McEwen: And he used something called the perceived stress scale, which actually asks you questions about how much in control of your life you are in and what things are causing you to be stressed out. What he also did was to develop a human task which was very much like what he did with the rats, and they used functional brain imaging to define a circuit that was activated by this task. They could observe this circuit in these stressed students and they found that the more stressed out, the less efficient was the circuit, and they also showed an impairment on this behavioural task.

Now what they couldn't do was to look at the detail of the synaptic connections, but we believe that what we learned from the rat is translatable to the human. Now the good news is that when these students had taken the test and had a month off all these effects disappeared.

Natasha Mitchell: So they are reversible?

Bruce McEwen: Yes, so that emphasised the reversibility in the normal healthy brain. Now we're beginning to suspect that as the brain ages it may lose some of this resilience. Some of the work that we've been doing with Mark Kishiyama and Bob Knight, comparing low and high socioeconomic status kids, shows that there are systematic differences in the function of various circuitries within the brain. Mark's work has shown for example that there are differences in prefrontal cortical activation, the part of the brain that's out in front, behind the forehead. It appears that children from low socioeconomic status environments have greater vigilance, but at the expense of the ability to filter out kind of incoming stimuli.

And if you think about it it makes sense that kids growing up in poverty deal with far more in the way of threats, severe stressors that they have to be vigilant towards in order to protect themselves and often to survive. But it comes at the expense of developing the ability that also is located within the prefrontal cortex to discriminate between stimuli that are important and those that can be ignored.

Natasha Mitchell: Professor Tom Boyce. Obviously some children go on to succeed in the face of adversity, there are individual tales of resilience in this story about the biology of stress where the interplay of genetics, epigenetics and family environment probably play a part. That's an intense area of investigation for Tom's team now and their hypothesis is there's a group of adversity responsive genes—interesting.

Just on those shrinking dendritic branches of brain cells Bruce McEwen talked about, curiously, he thinks this could be the brain protecting itself from permanent damage by stress. For example in animals going into hibernation, the same dendrites can shrink in a matter of hours to conserve energy. But if the animals need to come out of their slumber to defend themselves, say, the dendrites rapidly grow back—isn't that amazing.

Interestingly your studies have revealed sex differences: that in male brains it seems that the reaction to stress is more severe than female brains. Give voice to that, I think that is interesting, there seems to be an inbuilt resilience that comes with oestrogen.

Bruce McEwen: Yes there is. Again from animal models we know that females do not show the same remodelling of their dendrites unless their ovaries are removed.

Natasha Mitchell: You don't see that same degree of shrinkage of the dendrites that branch into cells.

Bruce McEwen: Some of our recent work has shown that in females who have oestrogens on board there are changes in certain parts of the brain, especially in the prefrontal cortex and the amygdala that are produced by stress only when there are oestrogens on board. And we don't understand, there's actually the growth of nerve cells caused by stress. We don't know what this means functionally and what's even more interesting is that if you simply took a male, took the testes out and gave them oestrogens, you would not see the same responses as you would see in the male.

Natasha Mitchell: In the female.

Bruce McEwen: In the female, there is a period early in life, the period of sexual differentiation, the testes are producing testosterone that's programming the brain to be different and that's not happening in the female.
Natasha Mitchell: It's very interesting to contemplate that women might be more resilient, their brains might be more resilient to stress. You have to think about how that translates into behaviour.

Bruce McEwen: Well, but at the same time women are more prone on the average than men to anxiety and depressive disorders but……………

Natasha Mitchell: I wonder whether that's a protective response.

Bruce McEwen: I think it is. And men are more prone to conduct disorders and anti-social behaviour. The way I interpret it is that men and women take it out in a different way and, as you said, for the women this may be a protective response and I think in general women are more sensitive to the social environment on the average than many men are, there are obviously exceptions. Having a wife and three daughters and four granddaughters, and four grandsons as well, but I mean there are these very important and significant sex gender differences.

Natasha Mitchell: So given stress radically reconfigures our developing brain and body, how can we help parents and policy makers start us off on the right path in life?

Bruce McEwen: If a person develops a good self-esteem, which is often as a result of proper parenting, and I mean a good attachment, then they're going to have this sense of themselves that takes risks in a very careful way and feels rewarded when they are successful. When you see a little kid learning to tie his or her shoes and beginning to be able to manage life for themselves you begin to realise how each of us builds up this confidence in our ability to do things. There are many life skills that are not higher intellectual functions, things that we are learning all the time, and if you don't have these skills you just are helpless in a sense.

Natasha Mitchell: I mean you make the case that genetics itself doesn't necessarily explain how we respond differently to stress, but how we perceive stress has a fundamental influence on the biology of stress in the body, doesn't it? Perception and biology being connected—I think that is incredibly powerful.

Bruce McEwen: It gets back to the idea that the brain is the central organ of stress and decides if something is threatening, decides what to do about it. There's—just getting back to self-esteem—there's a very interesting study at Magill, by Jens Pruessner , showing that people who have low self-esteem have a smaller hippocampus. They were doing something called the Trier Social Stimulation test, which is a public speaking challenge. You put a person in front of a bunch of strangers and you ask them to talk about something very personal. If any one of us did it you can be sure that at the first time our heart rate would be pounding and our cortisol would go up. You ask people to do this several times in a row, each time with a different group of strangers, and you know. a different task. Most people who have good self-esteem habituate, their cortisol is not as large the second time and maybe the fourth or fifth time the heart rate goes up but it's no big deal. But he identified a group of people that had very high levels of cortisol the first time and they never habituated. And when he did standard profiles of their personality they had low self-esteem, low locus of control, they just didn't have this confidence in themselves. And then at Magill they found they had a smaller hippocampus, which of course governs cortisol secretion, the HPA access, but it also governs many aspects of our brain function, as we've already discussed.

So this is provocative finding, it needs to be borne out, but it suggests that early life events, the ability to develop a sense of yourself, the ability to control your environment—and of course on top of that the ability to be socially active, to have friends, not to isolate yourself, and learn all these life skills and so on, is what contributes to our ability to be resilient. Or when we're in a situation where we have a lousy job or a lousy relationship, to have the courage to stop and do something different.

Tom Boyce: The biological research that we and others have been doing, our hope is that it becomes part of a much larger frame that catches the attention and drives within policy makers and legislators and so on, within societies in general, a new kind of sense of the critical importance of how we care for and look out for our children.

Natasha Mitchell: You could imagine it as a sort of measure of interventions, if you like, if you mention cortisol levels before and after an intervention with a community of vulnerable children. That's an interesting possibility isn't it?

Tom Boyce: It is indeed, employing some of these biological measures in the service of the development and sculpting of interventions that would be more effective. It's far easier to measure differences in brain function before and after an intervention at age 5 than it is to wait for the consequences of the changes in brain circuitry that happened decades later in life.

Bruce McEwen: All public policies are health policies: a housing policy, a tax policy, an education policy, they are all affecting our health because if you're worried about your finances you're going to be stressed out. If you can't find a job you're going to be stressed out. So there are many things that will lead to this psychological stress. And so what government does and what the private enterprise does, if they give people a chance to plan their own working schedules, with day care, with other family responsibilities if they are given release time to go to physical activity, to exercise they are happier and they are healthier.

So all of these policies are good for the business because it's more productive, it's also good for the employee.
Natasha Mitchell: And good for the brain, brain based policy.

Bruce McEwen: Yeah, brain based policy. I mean it means reorganising society as much as we can to de-emphasise the pressure on the success—unfortunately the mighty dollar—to realise there's a life we want to live too and it's not all the bottom line.

Natasha Mitchell: Well Bruce McEwen thank you for joining me and it's been great to have you on the show.

Bruce McEwen: It's been an honour and it's been a lot of fun as well to chat with you.

Natasha Mitchell: Professor Bruce McEwen from Rockefeller University and before him Professor Tom Boyce from the University of British Columbia. The full interview with Bruce McEwen is on the All in the Mind blog. Lots more science unravelled there. And join the discussion on the All in the Mind website, look for 'add your comment' on this week's story at abc.net.au/rn/allinthemind. And there's our Audioboo channel of course too. I'm Natasha Mitchell. Next week, the divided brain and Western civilisation!

Guests:

• Tom Boyce, Professor of Pediatrics, University of British Columbia, BC Leadership Chair in Child Development in the Human Early Learning Partnership and the Centre for Community Child Health Research
  Vancouver, Canada http://www.earlylearning.ubc.ca/people_staff.htm#boyce
• Bruce S. McEwen, Neuroscientist and neuroedocrinologist, Alfred E. Mirsky Professor Harold and Margaret Milliken Hatch Laboratory of Neuroendocrinology' The Rockefeller University, USA http://www.rockefeller.edu/research/faculty/abstract.php?id=109
  

Role of cultural influences on perception

Highly sensitive people less influenced by culture
Sensitive Persons’ Perception Moderates Responses Based On Culture

Building on previous brain imaging research that revealed cultural influences play a role in neural activation during perception, Arthur Aron, Ph.D., Professor of Psychology at Stony Brook University, and colleagues, completed a study that suggests individuals who are highly sensitive have cognitive responses that appear to not be influenced by culture at all.

Reported in advance online in Social Cognitive and Affective Neuroscience, and scheduled for print in the June issue, the study could serve as a foundation for the direction of study in the emerging field of cultural neuroscience.

“Our data suggest that some categories of individuals, based on their natural traits, are less influenced by their cultural context than others,” says Dr. Aron.

He adds that the study is the first to analyze how a basic temperament/personality trait, called sensory processing sensitivity (SPS), interacts with culture and neural responses.SPS is characterized by sensitivity to both internal and external stimuli, including social and emotional cues. Scientists estimate that something like high sensitivity is found in approximately 20 percent of more than 100 species, from fruit flies and fish to canines and primates and has evolved as a particular survival strategy that differs from the majority.

The standard measure in humans is the Highly Sensitive Person (HSP) Scale, previously developed by Dr. Aron and his wife, Dr. Elaine Aron. An example of one item on the HSP scale is “do you seem to be aware of subtleties in your environment.”

Dr. Aron says those who score high on the scale report being easily overwhelmed when too much is happening, startle easily, are conscientious, enjoy the arts more, and have a lower pain threshold. They are more emotionally reactive and more affected by the environment compared to those who score low on the scale.

The researchers measured SPS in 10 East Asian individuals temporarily in the U.S. and and 10 Americans of Western-European ancestry. In a previous study, these same 20 individuals had undergone brain functional magnetic resonance imaging (fMRI) while performing a cognitive task of comparing the length of lines inside boxes.

The participants’ responses to the task tested their perception of the independence versus interdependence of objects as the fMRI measured the neural basis of their responses.The major finding of that study was that the frontal-parietal brain region (see Figure in original news release) known to be engaged during attention-demanding tasks was more activated for East Asians when making judgments ignoring context, not their specialty, but was more activated for Americans when making judgments when they had to take context into account, not their specialty. This discovery, says Dr. Aron, illustrated that each group engaged this attention system more strongly during a task more difficult for them because it is not generally supported by their cultural context. That is, even when doing a simple, abstract cognitive task, culture influences perception.In the SPS study, Dr. Aron and colleagues took the brain activations in these two groups from the previous study and considered them in light of the SPS scores of the same individuals. They found SPS as a trait yielded a very clear pattern of results:

“The influence of culture on effortful perception was especially strong for those who scored low on the scale measuring sensitivity, but for those who scored high on the measure (highly sensitive individuals), there was no cultural difference at all,” says Dr. Aron.

Regarding the fMRI, Dr Aron adds: “Culture did not influence the degree of activation of highly sensitive individuals’ brains when doing the two kinds of perceptual tasks used in the previous study. "Also, how much they identified with their culture had no effect.

"It was as if, for them, culture was not an influence on their perception.”

Dr. Aron emphasized that the new research suggests that characteristics possessed by high SPS individuals, such as being emotionally reactive or conscientious, actually flow out of or are side effects of the overriding feature of processing information more thoroughly than low SPS individuals.While the results showed a clear, statistically significant connection between SPS, cognitive processing, and culturally-based thinking, Dr. Aron indicates that the small numbers of participants does not rule out the possibility that these results could be sample specific, so conclusions must be taken as preliminary and only as suggestive.

Replications of the study and larger sample sizes, he adds, would help to further the research.

Co-authors of the study titled, “Temperament trait of sensory processing sensitivity moderates cultural differences in neural response,” include: Sarah Ketay, Ph.D., Mount Sinai School of Medicine; Trey Heddan, Ph.D., Massachusetts Institute of Technology (MIT); Elaine N. Aron, Ph.D., Stony Brook University; Hazel Rose Markus, Ph.D., Stanford University, and John D.E. Gabrieli, MIT.

Stony Brook University News 5/3/2010