The Amygdala
By Michael Shea
Chapter 22 from his Forthcoming Book: Biodynamic Craniosacral Therapy Vol. I 2006

It is an interesting shift in the focus of craniosacral therapy when, at the end of his life, Dr. Sutherland realized that respect and reverence had to become an integral part of every cranial session. The practitioner has to maintain and embody an attitude of respect and reverence for the session to be efficacious. He even said in a lecture at the Des Moines College of Osteopathy that this work could be considered religious in nature. I think nowadays he would have said it was spiritual in nature. This is important to remember as I deepen into a discussion of how the brain works in this chapter and especially how the brain manages fear. I would like to suggest as Dr. Fulford did many years ago is that love, the love of the mystery of incarnation be an aspect of every treatment as well as respect and reverence.

Longing for a connection to the divine is one of the fundamental aspectsof the spiritual experience, which is the longing to transcend our sense of self. That longing is the way we know the Breath of Life. That’s the inherent plan of being at work within our body and mind. It is one of the self-correcting phenomena of the body and mind. It is the rhythm of the divine, so to speak. One must look inside the body rather than outside the body for a deep spiritual connection. That is the tragedy of our time that clients have such difficulties when encountering their sensorium because it has been imprinted with fear. That is the subject of this chapter – fear and its neurological centers of control.

In general there are three functional divisions of the brain. This distinction is based on Paul MacLean’s work in the 1960’s at the National Institutes of Health. He talked about the brainstem being the action brain. Then he talked about the middle part of the brain being the limbic system or the emotional brain and finally the cortex, which is the outer quarter, inch covering of the brain as being the thinking brain. Nowadays the limbic system has been renamed the corticolimbic system. That is the part of the brain I am going to talk about.

The neural tube, which is one of the first nervous system structures that appears in the embryo, is the future ventricle system. The ventricles, which are the open cavities in the brain filled with cerebrospinal fluid in the adult, appear first in terms of nervous system development. The neural tube fills with amniotic fluid in the embryo because there is no cerebrospinal fluid yet. Because of the growth pattern of the embryo being primarily oriented in the head region, there is a tremendous amount of growth that occurs on the upper end of the neural tube. The top of the neural tube differentiates into the third ventricle. The bottom of the neural tube grows slowly and has the appearance of a tail.

The third ventricle is right in the middle of the brain and therefore the corticolimbic system. From the anterior end of the third ventricle hangs the pituitary gland or the hypophysis as it is also called. Above the pituitary and also more properly is the anterior wall of the third ventricle called the lamina terminalis. The lamina terminalis is the embryological fulcrum for the entire central nervous system. It actually was the top of the embryonic neural tube when it first formed four weeks after conception. Some consider that the third ventricle and its lamina terminalis to be the very heart and soul of the biodynamic system.

The interthalamic adhesion joins the two walls of the third ventricle together right in the middle. Imagine that the third ventricle actually looks like a donut. The thalamus comes together in the middle (so the donut hole is actually an adhesion of the two sides of the thalamus) of the third ventricle. This causes a circulatory pattern of cerebral spinal fluid in the ventricle which biodynamic craniosacral therapy practitioners can sense within the Mid Tide level of palpation. In the posterior end of the third ventricle is the pineal gland.  There is also a vector of Mid Tide potency between the pineal gland in the back of the third ventricle to the pituitary gland in front. This vector is the whole neuroendocrine system axis and is a very important consideration for biodynamic evaluation. The tissue on the roof of the third ventricle is the choroid plexus, where some of the cerebral spinal fluid that fills the whole ventricle space is produced. The bi-lateral foramens of Monroe go into the lateral ventricles on either side of the third ventricle. Cerebrospinal fluid circulates from the lateral ventricles into the third ventricle and then moves down the cerebral aqueduct into the fourth ventricle and of course it then circulates back up.

The foramen of Monroe is another fulcrum that the whole brain moves around because it is the bilateral ducts between the lateral ventricles and the third ventricle that invited the rest of the brain to develop around. This is the heart of biodynamic craniosacral therapy. This is where the action begins and this is where it ends in the third ventricle with all of its different vectors and fulcrums of embryonic development. Dr. Sutherland said that the heart of the bird, the bird represents the Breath of Life in all cultures, rests in the third ventricle. He sensed the movement of the lateral ventricles as the wings of the bird and the fourth ventricle as the tail. Practitioners would be well advised to hold this image in mind when contacting a client’s cranium.

The important thing to remember is that the ventricles are at the core of the corticolimbic system, which is called the emotional brain by most everyone these days. Dr. Allan Schore has put the corticolimbic system on the map as the most important function of the brain especially in infants (Schore 2005) The third part of the brain in MacLean’s nomenclature is the cortex, which is the outer quarter inch part of the brain called the thinking brain. The cortex as we have seen in previous chapters includes the prefrontal cortex, which is the apex of the entire corticolimbic system. So, to repeat myself: the action brain, the emotional brain, and the thinking brain are the three functional divisions of the brain. I wish it were that simple because in reality the brain is operating holistically and is everywhere working at the same time with some areas having higher concentrations of metabolic activity than others depending on the experience being perceived at any given time. Teaching wise, however, the triune brain model is great because it gets us into the ballpark of function rather than structure. The brain just loves to learn and it does so by the level of emotional neurochemicals, which lays down memories in its neurons from the pre, and perinatal time of life. The brain takes experience and learns from it and uses it to modify behavior from moment to momentover a lifespan but especially prenatally and perinatally.

I want to name some of the structures in that system for you and why they are really important in our understanding of the self-regulation of emotional states because self-regulation occurs as a function of the development of the corticolimbic system. The thalamus is the structure sitting on top of the brainstem. It essentially receives all incoming sensory information coming up from the body and has to relay it to the appropriate place in the brain for possible motor action. The appropriate place is called the hypothalamus.

Basic responsiveness to incoming stimuli is going to be done by the hypothalamus at the anterior end of the thalamus. Remember that it is the third ventricle that invites a structure called the hypothalamus to form around it in the embryo. It looks like a box of dominoes around the third ventricle. The hypothalamus is a co-regulator of the entire autonomic nervous system (ANS). The hypothalamus is a really crucial part of the ANS because it co-regulates the sympathetic nervous system and the parasympathetic nervous system. The hypothalamus is considered the upper ganglion of the ANS. It contains about 13 or 14 nuclei, all having to do with the mobilization of deep social resources in the body: fight-flight, digesting food, getting sex, having fun with sex, and regulating painful and pleasurable emotions all of which nature has designed to be located in one structure of the brain. All of those various functions are connected to the pituitary gland, which as I said above hangs off of the anterior end of the hypothalamus, and consequently secretes hormones into the blood stream based on the information coming from the hypothalamus. These hormones such as noradrenalin have powerful effects on the two principal divisions of the ANS called the sympathetic and parasympathetic nervous systems. The sympathetic and parasympathetic nervous systems are coupled together and function reciprocally for approach behaviors of joy or aggression or withdrawal behaviors of relaxation or collapse and freeze behaviors. It is very important to understand these functions because of the way stress is known to alter them.

The corticolimbic system is a bilateral horseshoe shaped structure that adheres together in its top middle section called the cyngulate. If the prefrontal cortex and hypothalamus is the apex of the corticolimbic system, then what is at the bottom of this powerful system? It is called the amygdala.  It is another critical bilateral structure located in the temporal lobes of the brain. It contains a group of 11 nuclei. Nuclei are clusters of neurons that have a particular job or function. Each amygdala is about the size of an almond. It is at the nadir of this whole self-regulating emotional affect system. As we go up the horseshoe of the corticolimbic system, the amygdala is first connected to a structure called the hippocampus. This part of the paired horseshoes loop around in back of the thalamus and merge with a structure called the fornix, which is a very strong thick band of interconnecting neurons that brings the information from the amygdala and the hippocampus forward around to the front end of the horseshoe through the cyngulate to the hypothalamus and even forward of it into the prefrontal cortex which is the apex of the corticolimbic system. Now you can get a sense of the whole limbic circuit as it is called.

The majority of these nuclei in the amygdala are oriented to the perception of fear. This is important to remember. Sensory information comes in and the amygdala places a charge on it based on past experience.The amount of the charge or its valence moves the information forward to the hippocampus, fornix, cyngulate, hypothalamus and prefrontal cortex. The majority of the nuclei of the amygdala on the left hand side are oriented to perceiving fear in the vocal tones of people around us and on the right hand side is ultra sensitive to the arm gestures, body movement and facial expression of the people around us. In other words, as I look at or listen to another person, I am constantly evaluating unconsciously whether I need to be afraid or not. This is called expectation theory. My expectations are created during the prenatal and perinatal time of life as implicit and explicit memory. This function begins in the amygdala and is connected to deeper defensive structures in the brain stem, the action brain that MacLean also called the reptilian brain because of its primitive defensive behaviors that it can cause (MacLean 1993). The amygdala is imprinted with our earliest memories, as is the hippocampus that it connects to.
Let me say something right here because it is critical. The amygdala is the first corticolimbic structure that comes online even before birth at the beginning of the third trimester. It is the primary functioning center of the infant’s brain for the first three months after birth. It is exceedingly important to understand the amygdala. The amygdala takes external information from the caregiver and the caregiver’s environment including other people and can store it as a kind of primitive information like a sixth sense so to speak and will also send it right to the hippocampus when triggered at any time. The main thing to remember about the hippocampus is that when information from the amygdala comes to the hippocampus, the hippocampus stores the information as a memory, as a neural network in the right hemisphere of the brain. It is the way I learn from my experience.  I’d better build a library of neural networks that can quickly be retrieved when I need to modify my behavior to get my needs met as an infant (and thus throughout life). This is the way I form expectations about life from early memories from the preverbal time of life. These needs seem pretty simple after birth, a breast for milk, a clean diaper, a warm environment, lots of hugs and kisses etc. Certainly we all got that, didn’t we? The reality is that it is an enormous amount of work for a caregiver to meet these basic needs. This is why mothers are said to be “good enough” when meeting as much of the demands of child rearing responsibilities as is possible. It is impossible to meet all of the infant’s needs all the time.
So the hippocampus stores the memory in the right hemisphere. Storage is not a linear process. It sounds like it is convenient that we can go into the storage locker, unlock it, and put something in it or take something out. Actually, it works as a series of associations based on expectations based on the preverbal memory in the brain. Part of the association goes in one part of the cortex let’s say as a smell or the corner of one eye of the caregiver that habitually lifts up. Another association is the actual pressure of the physical contact or lack thereof etc. It is these human interconnections, resonances and associations that are encoded or imprinted in the right hemisphere as memories. Ultimately the stronger repetitive memories of this preverbal period of life become belief systems and as an adult we have no conscious recall of how they originally got set in place. If I had to make a lot of noise as a baby to get fed then my behavior as an adult is likely to reflect the increased autonomic tone that got imprinted then. The main difference is that screaming may not be as effective as lets say lying or projection or passiveness.

It only takes a shade or a shadow of an experience to trigger an entire complex, because the association then triggers the fight-flight mechanism in the hypothalamus and all of a sudden you have a full-scale activation. This kind of upheaval in the autonomic nervous system is seven synapses below conscious awareness at the beginning and may cascade into a state of hyperarousal and then collapse to get the person’s attention. Many people walk around during the day getting activated by the slightest thing and are not aware of it. This is a great survival strategy, this is a fabulous strategy and like it or not in Homo sapiens, the brain is oriented towards the perception of danger. That’s just the way it is from an evolutionary perspective. We spent millions of years being very low on the food chain. Now it seems that we are on the top of the food chain but still act like we are on the bottom. Consequently, bringing conscious awareness to the activity of the autonomic nervous system is critical for rehabilitating it.

We are also wired for joy in the prefrontal cortex, which comes on line at ten months post birth. The prefrontal cortex is the apex of the corticolimbic system as I said just in front of the hypothalamus. We have to grow the neural connections for joy from the hypothalamus to the prefrontal cortex and that is dependant on the quality of our attachment experiences with our mom. Those quality experiences give one the ability to self regulate states of fear in the body. I do not have to live in fear of the world. The consequence of too much fear early on is, if I do not get quality experiences, those synaptic connections for self regulation die. It is called selective parcelation. Life experiences will then shape the brain unconsciously and you will wonder why you do not have a lot of say in it. When the prefrontal cortex gets wired together in infancy from a secure attachment, it has the capacity to self regulate felt states in the brain and body consciously. These connections from the top down in the corticolimbic system are ten times more numerous than the bottom up connections, so that even in an insecure attachment one could get partially hooked up and still have a fair amount of self-regulatory capacity available. Even a little bit of love goes a long way.

It means that the amygdala does not have a built in executive controller that says, “Hey, chill out, that person is OK”. That is what the prefrontal cortex is designed to be able to say. But remember, those connections must be grown based on the quality of emotional experiences with the primary care giver. What the research shows is that without those prefrontal hookups the corticolimbic system will default to the parasympathetic system (PNS) which is of course connected to the amygdala. The PNS will up-regulate itself massively to modulate highly charged sympathetic nervous system states from a runaway amygdala. This causes strong inhibitory behaviors such as freezing and dissociation. To accomplish this, the PNS uncouples from the sympathetic nervous system (SNS). This is a set up for being sensitized to post traumatic stress disorder (PTSD) later in life. Even infants, however, can get post traumatic stress disorder and this is a great tragedy.

Those clients with PTSD go through their life with a basal metabolic decrease in left hemisphere activity. Left hemisphere function is 20-30% off-line during unstressful moments. Even when I am not under stress, so to speak, but just going through my day, I am not playing with a full deck. But if I undergo some stress my left hemisphere can go up to 80% off line. The left hemisphere as I pointed out in the chapter on hemispheric lateralization is responsible for integrating an accurate relationship with the outside world for one thing and speech as well. This is one reason that the PTSD client feels so hopeless and isolated and unable to express feelings.

The right hemisphere is constantly up-regulated in the client who holds shock and trauma. This is one of the gifts that the trauma resolution community has given the world of biodynamic craniosacral therapy. Rather than the practitioner not wanting or intending to activate the client’s trauma schema, the practitioner must remember that the client is already activated; the client is living in the aroused state most all of the time. Most everyone I believe is living in a state of alarm or fight-flight because we now live in a PTSD world since 9-11. The right hemisphere is on hyper-alert for the next unnegotiated thing that is going to collapse onto and into my world. So, you put this PTSD client in even a small amount of stress and the left hemisphere is going to go off-line for the most part. He feels mentally confused, activated with a high heart rate, etc. and he does not know how he got there. The practitioner is acting as a surrogate left hemisphere for the client and witnessing the right hemisphere of the client at the same time.Then the practitioner synchronizes with Primary Respiration and allows the fluids to resource the brain and integrate its activity.

At the far end of its functional capacity the parasympathetic nervous system co-regulates dissociation. The parasympathetic nervous system allows us to numb out and not feel the fear, not to be conscious of it. And the beauty of the parasympathetic system is that not only will it do this dance and allow us to dissociate, in this up-regulatory state, but also in that state it will trigger what are called SIA’s, stress induced analgesics. It will allow the brain stem to flood the brain with endogenous opiates like endorphins and so, you get this beautiful opium response. It is really incredible how the brain and the body are capable of adapting to the most severe conditions even as an infant. These are very powerful organismic resources. And a craniosacral therapy practitioner comes along and starts lightly touching the client and wonders sometimes how with such seemingly benign contact the client is up on the ceiling autonomically. One teacher of mine called it the autonomic festival. I have seen it frequently in my years of practice.

If for some reason a person did not have a secure attachment, or did not get enough of it or got some but not all, this means that there are degrees of an insecure attachment. This also means that the executive control center in the prefrontal cortex did not fully come on line and the capacity to self regulate is diminished by degree. What happens is that since one cannot rely on the prefrontal cortex, the amygdala will be constantly kindled or activated by the world of the senses. There is too much TV, too much media, too much stimulation and above all too much speed. Consequently one is going to rely unconsciously on the parasympathetic nervous system to calm down as well as excessive behaviors of all kinds. The ANS goes into its default mode of operation, which is called uncoupled non-reciprocal ANS function. This is pretty heavy duty for the body, behavior, the heart, the bowels and your spouse.

The autonomic system literally becomes uncoupled. The sympathetics are just free to do their activated state and the parasympathetics are also activated and not too interested in helping the SNS to down regulate, slow the heart and chill out. The felt sense of this is calm on the outside, activated on the inside or you can get varying degrees or shades of that as well depending upon one’s genetic constitution. Some people are hot on the outside but they can be cool on the outside. Some say it is the difference between New York genes and California genes.

This is called the fight-flight-freeze system. A lot is known about this system and guess what; many people got habituated to fight-flight between 3-18 months after birth and most likely even were imprinted with fight-flight prenatally as well. Dissociation and fight-flight is so far below conscious awareness that it is epidemic right now in our culture. If you are aware of fight-flight, then it is possible to get out of it and heal it. It is a whole process in trauma resolution work; nonetheless it can be resolved or brought into a more functional way of being in the world with love as something tangible rather than theoretical. Love really is the answer.

This ANS is on overload in many people. It causes the adrenal glands to secrete an anti-inflammatory steroid called cortisol.  When the immune system senses a lot of cortisolfloating around, guess what the immune system does. It turns on. It creates a little brush fire, fight fire with fire, let me create a little brush fireand get ready for the big one when it comes. What has happened is that one moves from an externally based perception of body via fight-flight to an internally based perception of danger immunologically and the body begins to fight itself internally. It is very hard to turn this function off and is responsible for a lot of chronic pain. The client could just trip and sprain his ankle and six months later he is on all sorts of medications and getting all sorts of therapy and all he did was to sprain his ankle. But his whole system was sub-clinically irritated from accumulated stress and underlying prenatal and perinatal stress and waiting for the next physical insult to set it off. It just took that little thing and bingo, the whole nervous system and body lights up like a Christmas tree and all of a sudden the immune system starts cranking up a big response.

This is what is so important to understand the complexities brain-body interactions. It is one reason why teachers spend so much time training students to avoid unbounded or aggressive touch. Because this quality of touch, any touch at all, has the potential to trigger these deep immune system responses. Believe me I have seen this often enough in my clinical practice. The thing that everyone could use which is appropriate physical touch, itself creates a double bind for clients. Because it gives the client an unconscious sense of conflict carried on the inside of the body and mind, not only physiologically but also emotionally. The very thing one needs, loving touch, is irritating.

Given all that wouldn’t it be a lot wiser to see if we could find the forces outside of the nervous system that had the capacity to modulate all of this function and build a resource for healthy functioning? Allow the animal in the client to come to the practitioner by synchronizing her attention with stillness and silence, the potency of the Breath of Life and Primary Respiration. That is why the practitioner needs to move her attention out into nature and invite the mind of nature to permeate the client at a slow tempo.

What we do in class is to park our psyches out on Saturn. Let us find the midline of moving out, moving back, moving out, until we find the right place in the slow tempo of Primary Respiration. We find the right place to watch from, not only from within the central nervous system in the witness center of the prefrontal cortex, but also in observing the forces of healing outside the nervous system which are related to Primary Respiration located in the fluids. We drop to the bottom of the ocean as one osteopath has said and wait, watch and wonder.