Posts Tagged ‘Amygdala’

Trauma and Emotional Relearning

March 21, 2018

The title of this post is identical to the title of a chapter in Daniel Goleman’s book “Emotional Intelligence.” The primary topic of this chapter is the frequently discussed and written about Post Traumatic Stress Disorder (PTSD). PTSD is a disorder of the limbic system. The main symptoms of such learned fearfulness, including the most intense kind, can be accounted for by changes in the limbic circuitry focusing on the amygdala. Some key changes are in the locus ceruleus, a structure that regulates the brain’s secretion of two substances called catecholamines: adrenaline and noradrenaline. The neurochemicals mobilize the body for any emergency; the same catecholamine surge stamps memories with special strength. This system becomes hyperactive in PTSD, secreting extra-large doses of these brain chemicals in response to situations that hold little or no threats, but somehow are reminders of the original trauma.

The locus ceruleus and the amygdala are closely linked, along with other limbic structures such as the hippocampus and hypothalamus; the circuitry for the catecholamines extends into the cortex. Changes in the circuits are thought to underlie PTSD symptoms, which include anxiety, fear, hyper vigilance, being easily upset and aroused, readiness for fight or flight, and the indelible encoding of intense emotional memories. One study found that Vietnam vets with PTSD had 40% fewer catecholamine-stopping receptors than did men without the symptoms, suggesting that their brains had undergone a lasting change, with their catecholamine secretion poorly controlled.

Other changes occur in the circuit linking the limbic brain with the pituitary gland, which regulates the release of CRF, the main stress hormone the body secretes to mobilize the emergency fight-or-flight response. The changes lead this hormone to be overselected—particularly in the amygdala, hippocampus and locus ceruleus—alerting the body for an emergency that is not there in reality.

A third set of changes occurs in the brain’s opiod system, which secretes endorphins to blunt the feeling of pain. It also becomes hyperactive. This neural circuit again involves the amygdala, this time in concert with a region in the cerebral cortex. The opioids are powerful numbing agents, like opium and other narcotics that are chemical cousins. When experiencing high levels of opioids, people have a heightened tolerance for pain.

Something similar seems to occur in PTSD. Endorphin changes add a new dimension to the neural mix triggered by preexposure to trauma: a numbing of certain feelings. This seems to explain a set of “negative” psychological symptoms long noted in PTSD: anhedonia and a general emotional numbness, a sense of being cut off from life or from concern about others’ feelings. Those close to such people may experience this indifference as a lack of empathy. Another possible effect may be dissociation, which includes the inability to remember crucial minutes, hours, or even days of the traumatic event.

The neural changes of PTSD also seem to make a person more susceptible to further traumatizing. A number of studies with animals have found that when they were exposed even to mild stress when young, they were far more vulnerable than unstressed animals to trauma -induced brain changes later in life. This seems to be a reason that, exposed to the same catastrophe, one person goes on to develop PTSD, and another does not: the amygdala is primed to find danger, and when life presents it once again wth real danger, the alarm rises to a higher pitch.

All these neural changes offer short-term advantages for dealing with the the grim and dire angers that prompt them. However, these short-term advantages become a lasting problem when the brain changes so that they become predispositions, like a car stuck in high gear. The amygdala and its connected brain regions take on a new set point during a moment of intense trauma.

Dr. Judith Lewis Herman is a Harvard psychiatrist whose groundbreaking work outlines the steps to recovery from trauma. The first step is regaining a sense of safety, presumably translates to finding ways to calm the too-fearful, too easily triggered emotions circuits enough to allow relearning. Typically this begins with helping parties understand that their jumpiness and nightmares, hyper vigilance and panics, are part of the symptoms of PTSD. The understanding makes the symptoms themselves less frightening.

The sense in which PTSD patients feel “unsafe” goes beyond fears that dangers lurk all around them: their insecurity begins more intimately in the feeling that they have no control over what is happening in their body and to their emotions. This is understandable, given the hair-trigger for emotional hijacking that PTSD creates by hyper sensitizing the amygdala circuitry.

Medication offers some way to restore patients’ sense that they need not be so at the mercy of the emotional alarms that flood them with anxiety, keep them sleepless, or pepper their sleep with nightmares. Unfortunately, today’s medications preclude doing exactly what they would like to achieve. For now, there are medications that counter only some of the needed changes, notably the antidepressants that act on the serotonin system and beta-blockers like propanol, which block the activation of the sympathetic nervous system.

Patients also may learn relaxation techniques that give them the ability to counter their edginess and nervousness. A physiological calm opens a window for helping the brutalized emotional circuitry rediscover that life is not a threat and for giving back to patients some of the sense of security they had in their lives before the trauma occurred.

Another step in healing involves retelling and reconstructing the story of the trauma in the harbor of that safety, allowing the emotional circuitry to acquire a new, more realistic understanding of and response to the traumatic memory and its triggers. As patients retell the horrific details of the trauma, the memory starts to be transformed, both in its emotional meaning and in its effects on the emotional brain. The pace of this retelling is delicate; ideally it mimics the pace that occurs naturally in those people who are able to recover from trauma without suffering PTSD. In these cases there often seems to be an inner close that “doses” people with intrusive memories that relive the trauma, intercut with weeks or months when they remember hardly anything of the horrible events.

To summarize, psychotherapy serves as an emotion tutorial.


Harmonizing Emotions and Thought

March 10, 2018

The title of this section is identical to the title of a section in Daniel Goleman’s book “Emotional Intelligence.” The hub of the battles or cooperative treaties struck between head and heart, thought and feeling are the connections between the amygdala (and related limbic structures) and the neocortex. This circuitry explains why emotion is so crucial to effective thought, both with respect to thinking clearly and in making wise decisions.

Working memory is the memory we hold in conscious thought. The prefrontal cortex is the brain region responsible for working memory. However, circuits from the limbic brain to the prefrontal lobes mean that the signals of strong emotion—anxiety, anger, and the like—can create neural static, sabotaging the ability of the prefrontal lobe to maintain working memory. This is why we say we “can’t think straight” when we are emotionally upset. Continual emotional distress can create deficits in a child’s intellectual abilities, and cripple the capacity to learn.

If subtle, these deficits are not always tapped by IQ testing. However, they do show up through more targeted neuropsychological measures, as well as in the child’s continual agitation and impulsivity. In one study, primary school boys with above-average IQ scores we still doing poorly in school. Neuropsychological tests found that they had impaired frontal cortex functioning. They were impulsive and anxious, often disruptive and in trouble. This suggested faulty prefrontal control over their limbic urges. In spite of their intellectual potential, they were at highest risk for problems like academic failure, alcoholism, and criminality—not because their intellect is deficient, but because their control over their emotional life is impaired. The emotional brain controls rage and compassion alike. These emotional circuits are sculpted by experience throughout childhood. We leave those experience utterly to chance at our peril.

Dr. Antonia Damaiso, a neurologist at the University of Iowa College of Medicine, has made careful studies of just what is impaired in patients with damage to the prefrontal-amygdala circuit. Their decision-making ability is terribly flawed. Still they show no deterioration at all in IQ or in cognitive ability. In spite of their intact intelligence, they make disastrous choices in business and their personal lives. They can even obsess endlessly over a decision so simple as when to make an appointment.

Dr. Damaiso argues that their decisions are bad because they have lost access to their emotional learning. The prefrontal-amygdala circuit is a crucial doorway to the repository of the likes and dislikes we acquire over the course of a lifetime. Cut off from emotional memory in the amygdala, whatever the neocortex mulls over no longer triggers the emotional reactions that have been associated with it in the past. Be it a favorite pet or a detested acquaintance, the stimulus no longer triggers either attraction or aversion. These patients have “forgotten” all such emotional lessons because they no longer have access to where they are stored in the amygdala.

This research has lead Dr. Damasio to the counter-intuitive position that feelings are typically indispensable for rational decisions; they point us in the proper direction, where dry logic can then be of best use.

So it is a mistake to do away with emotion and put reason in its place, as Erasmus recommended. We need to find the intelligent balance between the two. The old paradigm held an ideal of reason freed from the pull of emotion. The new paradigm urges us to harmonize head and heart. And to do that well in our lives means we must first understand what it means to use emotion intelligently.

The Seat of all Passions

March 9, 2018

The title of this post is the title of a section in Daniel Goleman’s book “Emotional Intelligence.” In humans the amygdala (from the Greek word for “almond’) is an almond -shaped cluster of interconnected clusters perched above the brainstem, near the bottom of the limbic ring. There are two amygdalae, one on each side of the brain nested toward the side of the head. Our amygdalae are relatively large compared to that of any of our closest evolutionary cousins, the primates.

The amygdalae and the hippocampi (there is also a hippocampus on each side of our brains) were the two key parts of the primitive “nose brain” that gave rise to the cortex and the neocortex. These limbic structures do much or most of the brain’s learning and remembering; the amygdalae is the specialist for emotional matters. If the amygdalae is severed from the rest of the brain, the result is a striking inability to gauge the emotional significance of events; this condition is sometimes called “affective blindness.”

Here please indulge a digression by HM to one of the projects he did as a graduate student. It involved conducting surgeries and implanting electrodes into the amygdalae of rats. These rats were deprived of water for 24 hours and then given an opportunity to drink. An electric current was applied to the amygdalae of some rats when they drank the water. The control rats were not shocked. The following day, the rats that had been shocked refused to drink, whereas the control rats, of course, drank. If you find this study troublesome, so does HM. But it did provide definitive evidence regarding the role of the amygdalae.

A fellow human had his amygdalae surgically removed to control severe seizures. He became completely uninterested in people, preferring to sit in isolation with no human contact. Although perfectly capable of conversation, he no longer recognized close friends, relatives, or even his mother, and remained impassive in the face of their anguish at his indifference. Absent the amygdalae, all recognition of feeling as well as any feeling about feelings is lost. Life without the amygdalae is life stripped of personal meanings.

All passion depends on the amygdalae. Animals that have their amygdalae removed or severed lack fear and rage, lose the urge to compete or cooperate, and no longer have any sense of their place in their kind’s social order; emotion is blunted or absent. As the amygdalae were not destroyed in HM’s rats, the stimulated rats returned to normal.

Tears, an emotional signal unique to humans, are triggered by the amygdala and a nearby structure, the cingulate gyrus. Being held, stroked, or otherwise comforted soothes these same brain regions, and stops the sobbing. Absent amygdalae, there are no tears of sorrow to soothe.

Goleman writes, “the workings of the amygdala and its interplay with the neocortex are at the heart of emotional intelligence. When impulsive feeling overrides the rational—the newly discovered role for the amygdala is pivotal. Incoming signals from the senses let the amygdala scan every experience for trouble. This puts the amygdala in a powerful position in mental life, something like a psychological sentinel, challenging every situation, every perception, with but one question in mind, the most primitive: “Is this something I hate? That hurts me? Something I fear?” If so—if the moment at hand somehow draws a “Yes”—the amygdala reacts instantaneously, line a neural tripwire, telegraphing a message of crisis to all parts of the brain.”

“When it sounds an alarm, it sends urgent messages to every major part of the brain: it triggers the secretion of the body’s fight-or-flight hormones, mobilizes the centers for movement and activates the cardiovascular system, the muscles, and the gut. Other circuits from the amygdala signal the secretion of emergency dollops of the hormone norepinephrine to heighten the reactivity of key brain areas, including those that made the senses more alert, in effect setting the brain on edge. Additional signals from the amygdala tell the brainstem to fix the face in a fearful expression, freeze unrelated movements the muscles had underway, raise heart rate and blood pressure, slow breathing. Others rivet attention on the source of the fear, and prepare the muscles to react accordingly. Simultaneously, cortical memory systems are shuffled to retrieve any knowledge relevant to the emergency at hand, taking precedence over other strands of thought.”

The extensive web of neural connections of the amygdalae allows them, during an emotional emergency, to capture and drive much of the rest of the brain—including the rational mind.

Research by LeDoux showed that sensory signals from the eye or ear travel first in the brain to the thalamus, and then—across a single synapse—to the amygdala; a second signal from the thalamus is routed to the neocortex—the thinking brain. So the amygdala can respond before the neocortex, which mulls information though several levels of brain circuits before it fully perceives and finally initiates its more finely tailored response.

LeDoux concluded, “Anatomically the emotional system can act independently of the neocortex. Some emotional reactions and emotional memories can be formed without any conscious cognitive participation at all.” LeDoux conducted an experiment in which people acquired a preference for oddly shaped geometric figures that had been flashed at them so quickly that they had no conscious awareness of having seen them at all. Nevertheless, our cognitive unconscious will still have formed an opinion as to whether we like it or not, not just the identity of what we’ve seen. Goleman notes that “our emotions have a mind of their own, one which can hold view quite independently of our rational mind.”

© Douglas Griffith and, 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 with appropriate and specific direction to the original content.

Primed for Love

December 1, 2017

The title of this post is identical to the title of a chapter in Goleman and Richardson’s book, “Altered Traits: Science Reveals How Meditation Changes Your Mind, Brain, and Body.” Learning about compassion does not necessarily increase compassionate behavior. From empathizing with someone suffering to actually reaching out to help, loving-kindness/compassion meditation increases the odds of helping. There are three forms of empathy: cognitive empathy, emotional empathy, and empathic concern. People frequently empathize emotionally with someone’s suffering but then tune out to soothe their own uncomfortable feeling. However, compassion meditation enhances empathic concern, activates circuits for good feelings and love, as well as circuits that register the suffering of others, and prepares a person to act when suffering is encountered. Compassion and loving-kindness increase amygdala activation to suffering while focused attention on something neutral like the breath lessons amygdala activity. Loving-kindness acts quickly, in as little as eight hours of practice; reductions in usually intractable unconscious bias emerge after just sixteen hours. The longer people practice, the stronger these brain and behavioral tendencies toward compassion become. The authors conjecture that the strength of these effects from the early days of meditation may signal our biological preparedness for goodness.

A description of loving kindness meditation can be found in the previous healthy memory blog post SPACE. More will be written about loving kindness meditation later in this series of posts.

A Mind Undisturbed

November 30, 2017

The title of this post is identical to the title of a chapter in Goleman and Richardson’s book, “Altered Traits: Science Reveals How Meditation Changes Your Mind, Brain, and Body.” A key node in the brain’s stress circuitry, the amygdala, shows dampened activity from just thirty or so hours of Mindfulness Based Stress Reduction (MBSR) (enter MBSR into the search box of the Healthymemory Blog to learn more about MBSR). Other mindfulness training shows a similar benefit, and there are hints the these changes are trait like: they appear not simply during the explicit instruction to receive the stressful stimuli mindfully but even in the “baseline” state, with reductions in amygdala activation as much as 50%. More daily practice seems to be associated with lessened stress reactivity. Experienced Zen practitioners can withstand higher levels of pain and still have less reaction to this stressor. A three-month meditation retreat brought indicators of better emotional regulation, and long-term practice was associated with greater functional connectivity between the prefrontal areas that manage emotion and the areas of the amygdala that react to stress, resulting in less reactivity. An improved ability to regulate attention accompanies some of the beneficial impact of meditation on stress reactivity. And finally, the quickness with which long-term meditators recover from stress underlines how trait effects emerge with continued practice.

Super-you: Use Your Better Instincts to Crush Your Inner Bigot

December 14, 2016

In the 10 Dec 2016 issue of the New Scientist there was a series of articles whose titles began super-you.  HM is reviewing a select sample of these pieces.  This instincts piece is written by Caroline Williams.  HM does not like this use of the word “instincts.”  “Predisposing biases” would have been a more fortunate choice.  However, this article accounts for much of the ugliness prevalent throughout the world.  The quick explanation is that these people are in their default mode of feeling and thinking.  But this is a very low level of thinking.  It is System 1 processing using Kahmeman’s terms.

The unpalatable truth is that we are biased, prejudiced and racist.   We put people into mental boxes marked “us” and them”.  Implicitly we like, respect and trust people who are similar to us and feel uncomfortable around everyone else.  This tendency towards in-group favoritism is so ingrained that we often don’t realize we are doing it.  “It is an evolutionary hangover affecting how the human brain responds to people it perceives as different.

A study from 2000 found that just showing participants brief flashes of faces of people of a different race was enough to activate the amygdala (Neuroreport 11(11):2351-5, September 2000 can be found at  HM readers should know that the amygdala is a key component of the brain’s fear circuitry.  But the amygdala doesn’t just control fear; it responds to many things and calls on other brain areas to pay attention.   Although we’re not automatically scared of people who are not like us, we are hardwired to flag them.  As Williams notes, “evolutionarily, that makes sense:  It paid to notice when someone from another tribe dropped by.”

When Susan Fiske of Princeton University scanned volunteers’ brains as they looked at pictures of homeless people, she found that the prefrontal cortex, which is activated when we think about other people, stayed quiet.  Apparently these volunteers seemed to process these homeless people as subhuman (Social cognitive ad affective neuroscience, 2007 Mar. 2(1) 45-51.)

Fiske says “The good news is that his hard-wired response can be overcome depending on context.”  In both the homeless study and a rerun of the amygdala study Fiske found that fear or indifference quickly disappeared when participants were asked questions about what kind of food the other person might enjoy,   Fiske continues, “As soon as you have a basis for dealing with a person as an individual, the effect is not there.”

What we put in “them” and “us” boxes is flexible.  Jay Van Bavel of New York University created in-groups including people from various races, participants still preferred people in their own group, regardless of race.  It seems that all you have to do to head off prejudice is to convince people that they are on the same team (Pers Soc Psychol Bull, December 2012, 38, 12, 2012  1566-1578.

It appears that we are instinctively cooperative when we don’t have time to think about it.  Psychologist David Rand of Yale University asked volunteers to play gambling games in which they could choose to be selfish, or corporate with other players or a slightly lower, but shared, payoff.  When pressed to make a decision people were much more likely to cooperate than when given time to mull it over.

Williams concludes her article thusly:  “So perhaps you’re not an asshole after all—If you know when to stop to think about it and when to go with your gut.  Maybe, just maybe, there is hope for the world.”

© Douglas Griffith and, 2016. 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 with appropriate and specific direction to the original content.

Can You Remember Things that Never Happened?

March 24, 2016

This post is based largely on portions of the fourth chapter in Elixir J. Sternberg’s Book “Neurologic and the Brain’s idea Rationale Behind Our Irrational Behavior.” The title of this post is the same as the title of Chapter 4.  Regular readers of the health memory blog should know the answer to the question posed in the title.  The answer is “yes.”  Elizabeth Loftus and others have done extensive research in this area.  They have a variety of methodologies for implanting false memories so that they are definitely believed.  I saw an example of one of these experiments on the PBS program NOVA.  In this case the research participants were convinced of a crime that they never had committed.  To find previous posts on this topic enter “Loftus” into the search block of the healthy memory blog.

Sternberg begins the chapter with a quote from Gabriel Garcia Marquez that largely captures the workings of our memories.  “He was still too young to know that the heart’s memory eliminates the bad and magnifies the good, and that thanks to artifice we manage to endure the burden of the past.”

A research group in Israel filmed a young woman, with no history of memory problems for two days straight.  Except for the cameras they were ordinary days.  At various intervals over the next few years she filled out questionnaires that tested her memories of those days.  The researchers used fMRI while she was filling out these questionnaires.  Over time the more distorted her memory became for the details.  What was especially interesting was how her brain activity changed over time while filling out the recall questionnaires.  As time passed and the memory errors accumulated, her memory appeared to be less endless reliant on the activity of the hippocampus.  The fMRI revealed reduced activation there as her recollection became more distant.  Other regions of the brain, including the medial prefrontal cortex and associated regions, became more and more active.  The medial prefrontal cortex is associated with self-centered thinking.  Her memory was accessing not simply a record from a neurological file, but a representation stored across multiple systems.  Her memory drifted away from accurately recording the details of that time period and instead became focused on her.

“To a large extent, our memories define us.  Our personal history forges our self-image and assembles our store of knowledge.  When the unconscious system in the brain encodes our memories, it is shaping who we are.  It doesn’t record our experiences impartially as a video camera would, because it focuses on our role in the story, on the aspects that we care about.   At any given moment, there is a context of how we are feeling, our emotions at that instant, what we are expecting or dreading, and what that moment means to us.  It is on that basis that the brain begins to compose its first draft.”

Three years after 9/11, two groups of New York City residents were enrolled in an experiment to learn how their emotions at the time of the attacks might have affected their memory.  The first group of people who were in downtown Manhattan that day close to the World Trade Center, and who personally witnessed the events of that day,  The second group consisted of people who were in midtown several miles away.  As would be expected, the downtown group rated their memories as being more vivid, more complete, and more emotional instances that the midtown group did.  And they had more confidence in the accuracy of their memories, but the neurological results revealed a different story.

The hippocampus is the area key to episodic memory, of which recalling 9/11 is a conspicuous example, but depending on the type of memory being accessed, other areas of the brain may be recruited to varying degrees.  For example, the amygdala may be activated when the memory is of an emotional nature, and the posterior parahippocampal cortex will become more involved when the brain attempts to access the more meticulous spatial details surrounding the event.  The members of the midtown group showed activation of the posterior  parahippocampal cortex as they recalled the details of 9/11, but only trivial amygdala activity.  It was just the opposite for the downtown group.  They exhibited striking activity in the amygdala but not in the posterior parahippocampal cortex.  This neuroimaging suggests that the downtown group recalled the events of the day for their emotional impact at the expense of remembering peripheral details.  Studies have revealed that the more emotionally  affected people are in recalling 9/11, the better they are at consistently describing the central events of what happened to them that day, but the worse they are at providing reliable description of the emotionally  neutral details.

There is a technical difference between telling a lie and confabulation.  A person telling a lie knows that he is telling a lie.  However, a person confabulating is trying to make a coherent story where substantial memory loss has occurred.  The chapter begins and ends with a man with both severe mental and addiction problems and a faulty memory.  He continually tries to put together a coherent story from the scraps of memory he can access, because he does not want to admit that he does not know.  Although his is a clinical case, we all work to make coherent stories from what memories we can find.  The unconscious system takes a self-centered egocentric approach to construct good narratives.

Creative Time

December 27, 2014

Creative Time is another section in the chapter Organizing Our Time in Daniel J. Levitin’s book The Organized Mind: Thinking Straight in the Age of Information Overload. The section begins with a discussion of creativity and insight. We’ll skip this as many posts were written about insight fairly recently. Then he moves on to the topic of flow. Although flow has been discussed previously in this blog, it is an important enough topic and Levitin does provide some new information. Flow refers to the experience of getting wonderfully, blissfully lost in an activity losing all track of time, of ourselves, our problems. Flow is the sixth principle of contemplative computing as formulated by Dr.Alex Soojung-Kim Pang in his book The Distraction Addiction (you can use the search box to find these posts). The phenomena of flow were identified and discussed by Mihaly Csikszentmihalyi (pronounced MEE-high, CHEECH-sent-mee-high). It feels like a completely different state of being, a state of heightened awareness coupled with feelings of well-being and contentment. Flow states appear to activate the same regions of the brain, including the left prefrontal cortex and the basal ganglia. Two key regions deactivate during flow: the portion of the prefrontal cortex responsible for self-criticism, and the brain’s fear center, the amygdala.

Flow can occur during either the planning or he execution phase of an activity, but it is most often associated with the execution of a complex task, such as playing a solo on a musical instrument, writing an essay or shooting baskets. A lack of distractability characterizes flow. A second characteristic of flow is that we monitor our performance without the kinds of self-defeating negative judgments that often accompany creative work. When we’re not in flow, a nagging voice inside our head often says, “It’s not good enough.” In flow, a reassuring voice says, “we can fix that.”

Flow is a Goldilocks experience. The task cannot be too easy or too difficult, it has to be at just the right level. It takes less energy to be in flow than to be distracted. This is why flow states are characterized by great productivity and efficiency.

As mentioned earlier, flow is also in a chemically different state, although the particular neurochemical soup has yet to be identified. There needs to be a balance of dopamine and noradrenaline, particularly as they are modulated in a brain region known as the striatum, the locus of the attentional switch, serotonin, for freedom to access stream-of-consciousness associations, and adrenaline, to stay focused and energized. GABA neurons that normally function to inhibit actions and help us exercise self-control need to reduce their activity so that we are not overly critical of ourselves, and so that we can be less inhibited in the generation of ideas.

Flow is not always good. If it becomes an addiction, it can be disruptive. And it can be socially disruptive if flow-ers withdraw from others.

Levitin goes on to describe how creative individuals and groups structure their environments and lives to enhance flow.

© Douglas Griffith and, 2014. 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 with appropriate and specific direction to the original content.

The Amygdala and the Problem of Reverse Inference

January 18, 2014

This blog post is based on the book Brainwashed: The Seductive Appeal of Mindless Neuroscience by Sally Satel and Scott O. Lillenfeld. Please bear with me as this is just the third post that I’ve written based on a source viewed on my Kindle.

The amygdala is a small region on each side of the brain. So we all should have two amygdalae. They are located in the temporal lobes, one in each hemisphere. In popular reports the amygdala has become almost synonymous with the emotional state of fearfulness. This is true. When you experience fear, the amygdala lights up. I have personal experience with research on the amygdala that I conducted when I was a graduate student. This was back in the days before brain imaging. I surgically implanted electrodes in rats placed under anesthesia so that they would electrically stimulate only their amygdalae. They were deprived of water and when placed in the operant chamber, they immediately started drinking. They received a shock after drinking. When they were placed back into the operant chamber they would not drink even if they were thirsty. However, if an electric current had been sent to the amygdalae when they were shocked the memory of the shock would never have been formed, so they would drink without fear when placed back in the operant chamber.

Although the amygdala is involved in fearfulness, it also responds to things that are unexpected, novel, unfamiliar or exciting. “This probably explains its increased activation when men look at pictures of a Ferrari 360 Modena. The amygdala reacts to photos of faces with menacing expressions, but also to photos of friendly, unfamiliar faces. If fearful faces are expected and happy faces unexpected, the amygdala will respond more strongly to the happy faces. The amygdala also helps register the personal relevance of a stimulus at a given moment. For example, one study revealed that hungry subjects manifested more robust amygdala responses to pictures of food than did their nonhungry counterparts.1

This amygdala example illustrates the problem of reverse inference, which is a problem that plagues the popular media. Reverse inference is the common practice of reasoning backward from the neural activation viewed in an image to subjective experience. The problem is that brain structures rarely perform single tasks, so one-to-one mapping between a given region and a particular mental states is highly prone to error. So “When Jeffrey Goldberg views a picture of Mahmoud Ahmadinejad and his ventral striatum lights up like a menorah, some investigators might think, ‘Well we know that the mental striatum is involved with processing reward, so this subject, with his activated mental striatum is experiencing positive feelings for the dictator’”2 This would be true only if the ventral striatum exclusively processed the experience of pleasure. But novelty can also stimulate the ventral striatum.



© Douglas Griffith and, 2013. 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 with appropriate and specific direction to the original content.


April 15, 2012

Resilience is one of the dimensions of Davidson’s Six Dimensions of Emotional Style.1 It refers to how quickly you bounce back from adversity. Do you bounce back quickly or do you let something bad keep you down for a prolonged length of time? Resilience is another “Goldilocks” variable in that you can have either too much or too little of it. Moreover, what is “just right” regarding resilience depends on the situation. If you just failed an examination, it might be worthwhile ruminating about it for a reasonable amount of time, not too excessive, trying to understand why you failed and how you might avoid similar failures in the future. However, you often see athletes compound an initial error by stewing over it, rather than quickly getting over it and attending to the immediate needs of the game or performance.

Davidson and his colleagues have performed some interesting research regarding the brain structures underlying resilience2. They did a study in which EEGs were recorded from the research participants scalps. Recordings of brain activity were done while 51 pictures were presented on a video monitor. However, before the pictures were presented the baseline level of brain activity was assessed for eight minutes. One-third of the pictures depicted upsetting images, another third pleasant images, and the other third neutral images. Sometime during or after a picture a short burst of white noise sounding like a click was presented. This was a startle probe that tends to make people blink involuntarily. Sensors were placed under one eye to determine when the eye blinked. When people are in a negative emotional state these startle-induced blinks are stronger than in a neutral state. When in a positive emotional state these startle-induced blinks become weaker still. This allowed the researchers to gauge how quickly a research participant recovered from a negative emotional state.

People who had greater activation in the left side of the prefrontal cortex recovered more quickly than the others. The amygdala is a subcortical structure (you have one in each hemisphere of your brain) that responds to negative or unpleasant stimuli. There is communication between the prefrontal cortex and the amygdala. Activity in the left prefrontal cortex shortens the period of amygdala activation allowing the brain to bounce back from an upsetting situation.

MRI brain imaging research has shown that the more white matter (axons that connect one neuron to another) lying between the prefrontal cortex and the amygdala, the more resilient you are. The less white matter lying between the prefrontal cortex and the amygdala, the less resilient you are.

Do not conclude from this that you are stuck with a fixed level of reslience due to the amoung of white matter you have between your prefrontal cortex and your amygdala. Research has indicated that this can be changed. In a later post, I will present techniques offered by Dr. Davidson as to how to change your level of resilience.

1Davidson, R.J. & Begley, S. (2112). The Emotional Life of Your Brain. New York: Hudson Street Press.