Posts Tagged ‘limbic system’

Mindfulness Based Stress Reduction

March 25, 2020

This post is based on an important book by Richard J. Davidson, Ph.D. with Sharon Begley, “The Emotional Life of Your Brain.” The remainder of the title is How Its Unique Patterns Affect the Way You Think, Feel and LIve—And How You Can Change Them. There have been previous posts on mindfulness based stress reduction (MBSR), which can be searched for in the search block at healthymemory.wordpress.com.

MBSR was developed by Dr. Jon Kabat-Zinn who learned meditation from a Zen missionary. Prof. Davidson writes, “MBSR is the most widely taught secular form of meditation in academic medical centers throughout North America and Europe. Developed by Jon Kabat-Zinn, of the University of Massachusetts Medical School in Worcester, the eight-week course teaches people to engage in mindfulness, the form of meditation in which you practice nonjudgmental, moment-to-moment awareness. Let HM take the three parts of that description in reverse order. By “awareness,” I mean that while sitting in a quiet place, you focus on whatever sensations your body is experiencing or whatever thoughts and emotions you mind is generating. You might start by feeling the pressure of the chair. Or the tension in your legs. Or how your elbow feels compared with your shoulder. Then you might move on to notice that as you conduct the mental inventory of your physical sensations, a thought about what to make for lunch pops into your mind. Or you notice that your brain feels suddenly quiet. The ‘moment-to-moment’ part describe how you take each sensation or thought as it comes. Finally, the ‘nonjudgmental’ part is key. If your legs feel tense, you do not scold yourself for having difficulty relaxing; your reaction is closer to ‘Huh, tense legs; interesting.’ Similarly, for any thoughts and emotions, you do not intentionally pursue a thought as you ordinarily might (Hmmm, lunch. I need to buy more mayo. Maybe I should have just a salad. I really need to eat less. Why am I thinking about this when I should be meditating? I’ll never get this.) If those thoughts arise, you observe them disinterestedly, as if from the perspective of a dispassionate observer, but do not take them to heart. They’re just the interesting exudations of your brain’s synapses and action potentials.”

By 2011, dozens of clinical trials had shown that MBSR can relieve psychological distress in breast cancer survivors, reduce side effects in organ-transplant recipients, relieve anxiety and depression in people with social anxiety disorder, and help people cope with chronic pain.

Prof. Davidson solicited volunteers, some of whom would learn a technique of stress reduction that was derived from Buddhist meditation, and some would be placed in a ‘wait-list’ control group,which meant undergoing the same assessments as their coworkers learning stress reduction, but not actually taking the classes. Which group some wound up in would be totally random. After the study was over, people in the wait-list control group would be given the opportunity to learn MBSR. The course consisted of one two-and-a-half session each week for eight weeks.

Before the first class baseline data was gathered on all the participants. Brain electrical activity was measured with EEG, focusing on the prefrontal cortex because that’s where left-right asymmetry is associated with positive or negative emotions and greater or lesser Resilience. Questionnaires were also administered that assessed how much anxiety and stress people felt, by asking them whether they agreed or disagreed with statements such as “I worry too much over trivial things” and “I often have disturbing thoughts.”

Anxiety symptoms fell about 12% among the people who took the MSBR class but increased slightly among the wait-list control group. The MSBR group also shows a significant shift toward greater left-side frontal activation: Compared with what it had been before the course, the level of left-side activation had tripled after four months. The control group had less left-side activation at the end of the study than they had at the start. Blood samples showed that meditators produced 5% higher levels of antibodies to a flu vaccine, an indication that their immune systems responded more effectively than those of the control group. Participants who showed a large brain response to MBSR also showed a larger response to the flu vaccine. Prof. Davidson believes that positive emotions (being Fast to Recover end of the Resilience style and he Positive end of the Outlook style) boost the immune system, among other beneficial effects on bodily health.

Prof. Davidson writes, “We all have habitual ways of responding to emotional challenges, and these habits are complicated products of genetics and experience. Mindfulness training alters these habits by making it more likely that one neuronal pathway rather than another will be used. If the habitual response to a setback had been for neuronal signals to travel from the frontal cortex, which figures out the meaning of the experience, to the limbic system, where the amygdala attached an intense negative emotional valence to that experience, then mindfulness can create a different neuronal pathway. The same experience is still processed by the frontal cortex, but the signals do not reach the amygdala (or at least fewer of them do). Instead, they peter out, like a bad mood evaporating during a day when everything seems to go right, The result is that what had been a stressful experience or setback no longer triggers a feeling of anxiety, fear, or fatalistic capitulations. The habitual path traveled by neuronal signals has changed—much as water that had always followed one path along a stream can be diverted to a different course after a sudden storm, for instance, carving a new channel. Mindfulness meditation carves new channels in the stream beds of the mind.

More specifically, mindfulness trains the brain in new forms of responding to experience and thoughts. Whereas the thought of how much you need to accomplish tomorrow (driving children to school; going to an important meeting for work, etc.,) used to trigger a panicky sense of being overwhelmed, mindfulness sends thought through a new culvert. You still think about all you have to do, but when the sense of being overwhelmed kicks in, you regard that thought with dispassion.)

Physical and psychological benefits can be found with other types of meditation. The relaxation response provides the easiest means of getting into meditation and has significant benefits by itself. Enter “relaxation response” into the search block of the healthy memory blog. The post “An Update of the Relaxation Response” documents the many benefits of this type of meditation.

Resilience: The Science of Mastering Life’s Greatest Challenges

March 5, 2020

The title of this post is the same as the title a book written by Steven Southwick and Dennis Charney. This post is the first of a series of posts based on this book. The American Psychological Association defines resilience as “the process of adapting well in the face of adversity, trauma, threats and even significant sources of stress—such as family and relationship problems, serious health problems, or workplace and financial stresses.”

Here are the key brain regions with respect to resilience:

The amygdala, which is associated with fear and alarm; it plays a central role in fear conditioning and in triggering raw emotions and the “fight or flight” response.

The prefrontal cortex, which is commonly referred to as the brain’s “executive center,” facilitates planning and rational decision-making; it helps regulate emotions and acts to keep the amygdala ( the “fear and alarm center”) in check.

The hippocampus, which plays a critical role in learning, forming new memories, and regulating the stress response; more so than many other brain structures, it is vulnerable to the effect of chronic stress.

The anterior cingulate cortex, which plays an important role in our ability to focus attention, detect and monitor errors and conflicts, assess the importance of emotional and motivational information, and regulate emotions; it is connected both to the prefrontal cortex and the amygdala.

The anterior insula, which is located in the fold of the cerebral cortex that marks the boundary between the frontal and temporal lobes; it is involved in functions related to emotions, and aids in the brain’s awareness of the body’s internal physical state.

The nucleus accumbens, sometimes referred to as the “pleasure center,” plays a central role in the brain’s reward circuitry; in association with the ventral segmental area, it mediates the experience of reward and punishment, and is associated with the pleasurable effects of food, sex, and drug abuse.

The limbic system refers to the inner portion of the brain—located beneath the cortex—which is involved in emotion, memory and other functions. It includes the amygdala, hippocampus, and a number of other structures and regions. Although the limbic system is neither a system nor a structure, the term provides a useful shorthand for referring to this area of the brain.

The autonomic nervous system is composed of two parts. The sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS). The SNS mobilizes the body under conditions of stress. The PNS conserves resources and maintains functioning under normal stressful conditions. During healthy functioning, it is beneficial for the SNS to have a robust response to stress and challenge, but also for the SNS to return to baseline rapidly after the stressful event is over. Another major system is the hypothalamic-pituitary adrenal axis (HPA axis), which responds to stress with a complex set of reactions involving the hypothalamus, the pituitary gland, and the adrenal glands.

Here are the different hormones and neurotransmitters that are involved in the stress response and resilience:

Cortisol is a stress hormone released through activation of the HPA axis. It produces energy by converting food into fat and glucose (a form of sugar). It also temporarily bolsters the immune system.
Epinephrine, also known as adrenalin, is part of the SNS. It is erased by the adrenal glands under conditions of stress and accelerates heart rate, constricts blood vessels and dilates air passages as part of the SNS fight-or-flight response.

Norepinephrine, also known as noradrenaline, is also part of the SNS. It facilitates alerting and alarm reactions in the brain and is critical for responding to danger and for remembering emotional and fearful events.

Serotonin is involved in the regulation of mood, as well as sleep, appetite, and other functions.

Dopamine is associated with pleasurable feelings and plays a key role in the reward systems of the brain. For this reason, it is an important factor in cravings and addictive behaviors.

Neuropeptide Y (NPY) is associated with decreasing anxiety and hastening return to baseline after the nervous system reacts to stress.

Oxytocin is associated with maternal behaviors, pair bonding, social communication, trust, social support, and anxiety reduction.

Brain-derived neurotrophic factor (BDNF) acts in support the nervous system through the repair of existing neurons an growth of new ones.

Our Two Minds

March 8, 2018

There are two fundamentally different ways of knowing to construct our mental life. The rational mind is the mode of comprehension of which we are typically conscious. It is more prominent in awareness, thoughtful, able to ponder and reflect. There is another system of knowing which is alongside it. It is the emotional mind. The emotional mind is impulsive and powerful, if sometime illogical. This emotional/rational dichotomy resembles the folk distinction between “heart” and “head.” Knowing something “in your heart” is a different order of conviction that is somehow a deeper kind of certainty than thinking with your rational mind. In “Emotional Intelligence” Goleman writes, “There is a steady gradient in the ratio of rational-to-emotional control over the mind; the more intense the feeling, the more dominant the emotional mind becomes and the more ineffectual the rational. This is an arrangement that seems to stem from eons of evolutionary advantage to having emotions and intuitions guide our instantaneous response in situations where our lives are in peril—and where pausing to think over what to do could cost us our lives.”

Goleman continues, “These two minds, the emotional and the rational, operate in tight harmony for the most part, intertwining their very different ways of knowing to guide us through the world. Ordinarily there is a balance between emotional and rational minds, with emotions feeding into and informing the operations of the rational mind, and the rational mind refining and sometimes vetoing the inputs of the emotions. Still, the emotional and rational minds are semi-independent faculties, each, as we shall see, reflecting the operation of distinct, but interconnected, circuitry in the brain.”

Most of the time these minds are well coordinated with feelings being essential to thought, and thoughts to feelings. However, when passions surge the balance tips: it is the emotional mind that captures the upper hand, swamping the rational mind.

To understand the potent hold of emotions on the thinking mind it is useful to understand how the brain evolved. Human brains, with their three pounds or so of cells and neural juices, are about triple the size of those in our nearest cousins in evolution, the nonhuman primates. Over millions of years of evolution, the brain has grown from the bottom up, with its higher centers developing as elaboration of lower, more ancient parts. The growth of the brain in the human embryo roughly retraces this evolutionary course.

The most primitive part of the brain for all species that have more than a minimal nervous system is the brainstem surrounding the top of the spinal cord. This root brain regulates basic life functions like breathing and the metabolism of the body’s other organs, as well as controlling stereotyped reactions and movements.

The emotional centers emerged from the brainstem. Millions of years later in evolution, from these emotional areas the thinking brain or “neocortex” evolved. The fact that the thinking brain grew from the emotional reveals much about the relationship of thought and feeling: there was an emotional brain long before there was a rational one.

New, key layers of the emotional brain came with the arrival of the first mammals. Because this part of the brain rings and borders the brainstem, it was called the ‘limbic’ system, from “limbus,” the Latin word for “ring.” This new neural territory added emotions proper to the brain’s repertoire. When we are in the grip of craving or fury, head-over-heels in love or recoiling in dread, it is the limbic system that has us in its grip.

The limbic system refined two powerful tools, learning and memory, as it evolved. These advances allows an animal to be much smarter in its choices for survival, and to fine-tune its responses to adapt to changing demands rather than having invariable and automatic reactions.

About 100 million years ago, the mammalian brain took a great growth spurt. Piled on top of the thin two-layered cortex-the regions that plan, comprehend what is sensed, coordinate movement—several new layers of brain cells were added to form the neocortex. In contrast to the ancient brain’s two-layered cortex, the neocortex offered an extraordinary intellectual edge.

Our neocortex, so much larger than in any other species, has added all that is distinctly human. It is the seat of thought; it contains the centers that put together and comprehend what the senses perceive. It adds to a feeling what we think about it—and allows us to have feelings about ideas, art, symbols, imaginings.

This new addition to the brain allowed the addition of nuance to emotional life. Limbic structures generate feelings of please and sexual desire. The addition of the neocortex and its connections to the limbic system allowed for the mother-child bond that is the basis of the family unit.

So the neocortex provided the basis for sophisticated interactions among humans.
However, problems can emerge when the neocortex loses the upper hand. Consider a nuclear war. Here it would be clear that the neocortex had lost the upper hand to the emotional mind. And it is possible that the neocortex justified the launching of a nuclear war and the extinction of homo sapiens. Such irony!

© Douglas Griffith and healthymemory.wordpress.com, 2018. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and healthymemory.wordpress.com with appropriate and specific direction to the original content.

Syndrome E

November 27, 2015

In the recent healthymemory blog post, “A Single Shifting Mega-Organism,” Syndrome E (E stands for evil) was briefly discussed.  Syndrome E was developed to describe the atrocities, mass-killings, genocides such as the holocaust and the killings by ISIS.  The neurosurgeon Itzhak Fried describes these atrocities as examples of Syndrome E.   He defined the following seven symptoms of Syndrome E:

Compulsive repetitive violence
Obsessive beliefs
Rapid desensitisation to violence
Flat emotional state
Separation of violence from everyday activities
Obedience to an authority
Perceiving group members as virtuous

Having decided that neuroscience has come a long way since his original paper in 1997 (Syndrome E in The Lancet, Volume 150, No. 9094, p1845-1847) Fried  organized a conference in Paris earlier this year to revisit the concept.  Highlights of this conference were published in the New Scientist, November 14-20, 2015 in a feature by Laura Spinney.

Fried’s theory starts with the assumption that people normally have an aversion to harming others.  If this is correct, the higher brain overrides this instinct in people with Syndrome E.  So how might this occur.

The lateral regions of the prefrontal cortex (PFC) are sensitive to rules from the newer parts of the brain.  The medial region of the PFC receives information from the limbic system, a primitive part of the brain that processes emotional states and is sensitive to our innate to preferences.  An experiment using brain scanning was designed to put these two parts of the brain in conflict.  Both these parts of the PFC were observed to light up.  People followed the rule but still considered their personal preference showing that activity in the lateral PFC overrode the personal preference.  The idea here is in the normal brain the higher brain overrides signals coming from the primitive brain.  However, in the pathological brain with Syndrome E, the primitive brain prevails.

Fried suggests that people experience a visceral reaction when they kill for the first time, but some become rapidly desensitized.  And the primary instinct not to harm may become more easily overcome when people are “just following orders.”  Unpublished research using brain scans has shown that coercion makes us feel less responsible for our actions.  Although coercion can cause people to take extraordinarily actions (see the healthy memory blog post “Good vs. Evil”), there are individuals who are predisposed to violence who are just awaiting an opportunity.

Unfortunately, the question remains as to how to prevent people from joining such radicalized groups.  Research in this area is just beginning and much more needs to be done (See the healthy memory blog post,”Why DARPA is studying stories”). Being a neuroscientist, it is not surprising that Fried thinks  that we should use our growing neuroscientific knowledge to identify radicalization early, isolate those affected and help them change.  We wish him, and hopefully many others in this effort.

What is not mentioned in this article is that it can be advantageous for one group to adopt Syndrome E to take from or to take advantage of another group.  Consider North America.  Syndrome E was involved in vacating Native American lands for Europeans.  Moreover, up until the Civil War, blacks were enslaved and slavery was a key component of the economy of the United States.  I sometimes ponder how would North America been settled by Europeans had we the moral and ethical standards of today.

© Douglas Griffith and healthymemory.wordpress.com, 2015. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and healthymemory.wordpress.com with appropriate and specific direction to the original content.