INTEGRINS

I have pondered, as many of us have, what happens in our clients’ bodies during Rolfing. I have not found the gel-sol model of connective tissue lengthening to be satisfying. Not that adding energy to connective tissue can’t change its properties, including its length, or even that something like this might be happening in Rolfing, I just haven’t found myself believing that the energy (pressure) we put into our client’s bodies is sufficient to effect such gel to sol reactions, and as I work with people, I don’t feel like that is what is happening. When I approach the tissue as a material that I must add energy to in order to make it longer, I don’t seem to get very far. In contrast, when I approach tissue as a receptive, listening material, I seem to get much farther.

As a result, the model of Rolfing that made the most sense to me was the proprioception model, presented by Robert Schleip in his 1991 Rolf Lines article, “Talking to Fascia, Changing the Brain.” In this model, Rolfing is more about a flow of information between practitioner and client than it is about a one-way process that effects change in a relatively inanimate material. The proprioceptors are the channels by which this information enters the body.

Figure 1 is from Schleip’s 1991 paper, and gives an overview of this flow of information. This model is still sound in my opinion, but recent observations from cell biology studies have extended this view, and in the process suggested a new vision of perception as a whole.

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In May of 1997 an article in Scientific American awoke me from my relative complacency on the topic of how Rolfing works. Alan Horwitz published a review paper on a class of cell membrane proteins known as integrins, which began to be understood in the late 1970’s. The opening lines of the paper changed my understanding of Rolfing and perception, and I repeat them here:

The cells of the body stick to one another and to the packing material, or extracellular matrix, around them. As might be expected, this adhesion holds tissues together and is therefore essential to survival. Less obviously, it helps to direct both embryonic development and an array of processes in the fully formed organism.

Figure 2 shows the shape and arrangement of integrins in the cell membrane. The proteins extend through the membrane so that one part is exposed outside the cell and another part is exposed inside the cell. The part of the protein outside the cell makes a mechanical connection with the extracellular matrix (ECM), collagen and fibronectin in the figure. The part of the protein on the inside of the cell makes a mechanical connection to the cytoskeleton (actinin fibers) and other proteins. Changes in the ECM and the attachments of the ECM to the integrins signals the cell to behave in particular ways. While the pathways of signaling are not completely worked out, it appears to occur both via the cytoskeleton and via chemical messengers. Changes in cell behavior include all the changes we expect with other types of cell signaling such as gene expression, migration, proliferation, and differentiation.

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Here is a mechanism that could transfer information directly from the ECM to cells and influence their physiology. Of course, the sheets of connective tissue, in all their forms, that we work with as Rollers are simply thickenings of, and continuous with, the ECM. It appears that information is taken in by our client’s tissue not only at the level of proprioception, but at a direct, cellular level without any mediation by the nervous system.

My vague notions of an information exchange model for Rolfing began to develop into a description that more fully fit my experience. If the tissue can “listen” on a cellular level, and if cells “know” something about the state of the ECM and connective tissue in their region of the body, then we have insight into the possible pathways by which “tissue memory” may occur, a deepened understanding of how structural organization may relate to experience, and the tissue specificity of Rolfing that seems to defy proprioceptor models of action. Proprioceptors surely mediate some of the larger scale movements and effects of Rolfing, but they are relatively sparse, populated among the cells of any given tissue, and are probably relaying information about relationships between bones and loads on whole muscles and structures. Integrins on the other hand seem well suited to pick up on a finer scale, and relay information about the relationship between cells and tissues that are in close proximity.

One other trait of integrins is that they appear to operate in both directions. Changes in the ECM affect the behavior of the cells, and changes inside the cells affect the “stickiness” of the integrins to the ECM. How well and in what way the cell attaches itself to the ECM is, it appears, influenced by the cell via the integrins.

I do not propose that integrins are the final word in the question of how Rolfing works, but suggest that this information opens our eyes to a whole new pathway of action. The integrin system might help us to understand the remarkable specificity of Rolfing, the profound effects Rolfing can have on a person’s state of mind and emotions, the phenomemnon of “tissue memory,” and the significant changes we observe in ourselves and our clients.

THE CHEMICAL LINK

But all this begs another question: How do cells affect the experience of an individual? We see that the ECM and cell physiology are closely related. But how do changes in cell physiology bear on changes that we commonly see in our clients? The link in the proprioception model are relatively easy to see. Muscles require a nerve impulse in order to contract, and proprioceptors are nerve sensors which are linked both directly to motor neurons and to the central nervous system (CNS).

But what is the pathway from the cells? A first answer is that nerves are cells. If the behavior of nerves is influenced by the surrounding ECM, then we can speculate that there might be a pathway from ECM to nerve cell to motor nerve cell, to muscle, which may or may not go through the CNS.

A more complete answer can be found in the work of Candace Pert. Pert has pioneered the view that physiology and behavior – including thoughts and emotions – are unified by chemistry. Her book, Molecules of Emotion, is a good summary of her view and contribution to our understanding. Briefly, Pert’s view is that certain molecules mean particular things inside the body. She calls these “information molecules.” When these molecules are present, all the tissues of the body, including the nervous tissue, change their behavior in response to the meaning of the molecule. In the presence of adrenalin for example, visual acuity goes up, pain threshold goes up, memory fidelity increases, time sense slows, immune function goes down, digestion stops, and the heart, lungs and muscles prepare for maximal activity. The unification of these activities occurs via adrenalin. The number and range of molecules that influence our experience in similar ways are myriad. Pert suggests that our emotional experiences are reflections of the continual flux and shifting concentrations of these molecules. The flourishing trade in medical and other drugs – synthetic information molecules – are further testimony to the truth of Pert’s view.

All cells both produce and monitor these molecules, though some tissues specialize in some molecules more than others. How any given cell behaves is significantly influenced by what molecules are present. This fact has a “figure-ground” impact on our view of synapses. Our prevailing model has been that our nervous system, like a computer, processes digital, electrical information, and that this information travels through nerves, much like a signal in a wire, until it gets to a synapse, where it must convert the electrical signal to a chemical one. The chemical signal must cross a gap to the next nerve, where it causes the second nerve to fire.

We now know that the behavior of a given nerve cell depends significantly on the chemical environment in which it finds itself. The chemistry in the synaptic cleft plays an important role in how the nerve will behave; how much stimulation it requires before it fires, how rapidly and how long it fires, and so on. The electrical impulses in the nerve cells are more reflections of their chemical environment than the other way around. The reliable effectiveness of Prozac and other mood altering drugs demonstrates this every day. The nerves stop looking so much like the intelligent directors, and more like the cables relaying results from one part of the body to the other. This can be summarized as follows:

“We are not digital, electronic information processing systems with slow chemical junctions; rather we are analog, chemical information processing systems with fast electrical junctions.”

Just as we have expanded our Newtonian view of movement and function in the body, perhaps we can now expand the computer model of information processing in the body.

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The information flow loop proposed in this paper. Sensory information, including Rolfing, is taken in by the integrin system as well as the proprioreceptor system. Synthesized sensory information is communicated to all body tissues, including the nervous system, via ?information molecules?. Note that there is no direct nervouslink even from proprioreceptors and tactile senses. Even in 2-neuron, proprioreceptor reflex systems, the signal must still pass via synapses, where information molecules are the mediators.

So a pathway from the cells to experience becomes clearer: from ECM to cell physiology to the “information molecules” of Candace Pert’s theory to the behavior of all tissues including CNS, muscle tissue, connective tissue producing cells, and perhaps connective tissue itself. Figure 3 provides a summary of this pathway.

To the extent that gel-sol style lengthening does occur, we can still speculate that any length changes induced in the connetive tissue are detected by integrins and proprioceptors, which in turn yield the effects we observe in ourselves and our clients.

If “information molecules” are the ultimate arbiters of our physiology and experience, it seems reasonable to expect that we would have a system such as the integrins to translate information about the mechanical environment into chemical information. Since nerves are a relatively recent evolutionary development, it also seems reasonable to expect that this translation was worked out at a cellular level first, and that nerve mediated translation – tactile and proprioceptive senses – are later, if essential, developments.

This raises an interesting point about the practice of Rolfing. We are accustomed to thinking that chemistry can affect our moods, behaviors and physiology. Adrenalin, opiates, and alcohol are only a few common examples. How will it impact the work we do if we consider that using our hands to work with the ECM may relay information directly to the physiology of cells and affect moods, behaviors, and physiology in a similar way? I propose that this model is more consistent with our actual experience in practice, and suggest that this is one of the important pathways yielding observable changes in our clients.

As an interesting aside, this pathway also adds insight into how experiences like exercise, dance, and other forms of movement can yield such sublime states of mind and changes in physiology.

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A NEW VIEW OF THE SENSES

As I pondered these ideas, I realized that I was now thinking of the integrins as part of our sensory system, much as we think of proprioceptors. But when we think of the senses, we think primarily of the nervous system; and the integrin system bypasses the nervous system altogether. Two things occurred to me: first, as mentioned above, the integrin system must be older evolutionarily than the development of the nervous system, and second, that we must have other “senses” that also bypass the nervous system.

The first of these other cellular-level systems to come to mind is the suite of chemical receptors that also dot cell membranes alongside the integrins. These receptors, like the integrins, have one part inside and one part outside the cell membrane. They detect various molecules outside the cell and signal the cell to adjust behavior and physiology accordingly. This “sense” is the basis for Candace Pert’s work, for the “chemical link” described above, and for all our familiar responses to changes in body chemistry ranging from oxygen and carbon dioxide levels, to hydration levels and hunger, to angiotensin and endorphins, to caffeine and LSD.

Seen this way, smell and taste, two of our conventional senses concerned with evaluation of the chemical environment, take on a new appearance. Fundamentally, taste and smell are cellular level evaluations of the chemical environment. In the tongue and nose are cells that detect and identify chemicals in ingested materials and the air. What distinguishes these as “senses” in our common view is that they have nerves that relay the information learned by the sensory cells to the rest of the system more quickly. It appears that we have a general, cellular level ability to evaluate, or “sense,” the chemical environment, and that some of these cellular level sensors are specialized by their attached nerves.

The same seems true for what I call the “mechanical” senses: hearing, tactile senses, proprioception, equilibrium, and, at the cellular level, integrins. All these senses tell us about the mechanical environment: the orientation to gravity; the load on a structure; the vibrations in the air; the texture, temperature and pressure exerted on the body’s tissues; and the state of the ECM. The ones we are familiar with as senses are the ones where a nerve is attached to a cellular-level sensor communicating the received information rapidly, and with spatial accuracy, to the rest of the system.

Even sight fits into this scheme. Vision is detection of the electromagnetic environment. It occurs first at a cellular level where rods and cones are capable of detecting a single photon. Interestingly, rhodopsin, the protein which actually encounters an incoming photon, is a cell membrane protein similar to integrins and chemoreceptors. Our vision sense is a cellular-level detector with nerves attached. Are there electromagnetic senses that occur only at the cellular level? We could posit that the production of melanin and vitamin D are cellular-level, electromagnetic senses, but we seem to have very few other structures for detecting the electromagnetic environment.

All this turns our catalog of the senses inside out. A typical listing of the senses yields five: Taste, smell, vision, hearing, and touch. Add to this proprioception and equilibrium and we have the full list of senses included in most physiology texts. The view I have presented above yields a different listing with three kinds of sensors: chemical, mechanical and electromagnetic. These are divided into evolutionarily older, cellular-level senses and more recent, nerve mediated senses. Table 1 gives an overview of this listing.

I find this expanded view of human senses enriching for my practice. Our common view, limited to seven nerve mediated senses, in turn limits our perception of how our clients perceive us as Rolfers. If Rolfing is in fact an information exchange process as suggested by Schleip, we benefit by having this expanded view of our sensing abilities. The catalog presented here reveals a rich and interwoven capacity to evaluate the environment on a variety of levels. The mechanical senses are the primary group that we use in Rolfing, serving both as the medium by which our client’s tissues “listen” to us as practitioners and the medium by which we know about our client’s tissues. We are, of course, using all or most of our senses all of the time, and Rolfing sessions are no exception. In light of these thoughts, Jan Sultan’s description of the “field” during a session takes on greater depth and significance.

REFERENCES

Dawkins, Richard, The Extended Phenotype, Oxford University Press, Oxford, 1982.

Juhan, Deane, Job’s Body, Station Hill Press, Barrytown, NY, USA, 1987.

Pert, Candace, Molecules of Emotions, Scribner, New York, 1997.

Schleip, Robert, “Talking to Fascia, Changing the Brain,” Rolf Lines, April/ May, 1991

Horwitz, Alan, “Integrins and Health,” Scientific American, May, 1997, Page 68

Sultan, Jan, personal communication, Fall, 1997[:de]INTEGRINS