The Physics of the Brain- Part 3

In the previous post, we discussed the importance of the temporal component in the functioning of the brain.  That neuronal synchrony (or binding) of the seemingly endless bombardment of sensory stimuli reaching our nervous system is achieved via an underlying "beat".  It therefore behooves us to take an exploratory journey into the wild and wacky world of brain research to try and piece together what the source of this "beat" is.  It is here that I reveal to you, what I opine, is one of the greatest and most relevant studies for our profession ever...... and it hasn't gotten a glance by most.

But first, some background and some arousal (not sexual).

Over the years, functional and anatomical studies of the brain has identified the thalamus as the principal relay centre for all sensory information (except olfactory) to the cortex.  It is proposed that the series of networks and circuits which make up the thalamocortical system is responsible for cognition and perhaps even be the foundation for consciousness itself.

The nuclei of the thalamus are subdivided into 2 distinctively different functional units- the specific thalamic nuclei and the non-specific nuclei.  In other words, there are 2 simultaneous systems functioning at the same time:  A baseline non-specific arousal system (via intralaminar and posterior thalamic nuclei) and a sensory specific system (via ventral and lateral nuclei) which is superimposed on the baseline activity.  When we observe lesions to each of these sets of nuclei, we get a clear understanding of their distinct functions.  If, for example, there is a lesion to the specific nuclei there exist a loss of a specific sensory modality (i.e.-visual, auditory etc).  However, if there is a lesion to the non-specific nuclei, patients are unaware of any input by the specific nuclei and even though those pathways still exist and are intact, they cannot  perceive or respond to them.

The perception of any specific sensory stimulus from our environment is absolutely dependent on the constant input from non-specific nuclei.   When measured, via EEG, this constant activity has been observed to occur in bursts or oscillations (~40hz).    When sensory stimuli are presented, these oscillations show a "phase locking" which allows for the cognitive processing and temporal binding of  such sensory stimuli.  Like receiving a "beat" count before beginning to play.

So while we know that there are brain regions with a high degree of localized function and control, we also know that there is no single region responsible for the integration of perception and memories.  When researchers first hypothesized the solution to the binding problem, they discovered thru their experiments that when subjects, for example, recognized faces the electrical activity of different regions of the brain became synchronized for a moment.  The synchrony appeared to be established by brain regions firing in a similar manner, as 40hz gamma oscillations.

This discovery explained that neurons are not only linked in space (as in actual physical synaptic connections) but also time. The brain can now have virtually unlimited possible combinations of neurons with a resultant limitless capacity for retaining information.  There now exists a logical and rational explanation to the mechanisms by which multiple sensory events come together into a single experience.

So what is the source of these thalamocortical oscillations which is so vital for us binding all our sensory information together?  Well, at first it was thought that they were an intrinsic property of the thalamus which was genetically programmed.  But in 1992, two scientists named Pinault and Dechev (published in the journal of Psychological Resarch) found that when they transected the dorsal column of the spinal cords in rats, the rhythmic depolarization of 40hz oscillations in the thalamic nuclei could no longer be recorded.  They showed that the source of this baseline activity was not an intrinsic property of the thalamus but pre-synaptic to the thalamus.  That, in fact, the source of the oscillations were a product of the neurons of the dorsal column and deep midline cerebellum.  Ultimately, they arise mainly from the muscle and joint afferents of the SPINE.

So, in summary, baseline arousal activity, signal to noise ratio and synchronization of the cerebral hemispheres (and hence high level perception) is thought to result from non-specific thalamic nuclei which trace back to the subcortical oscillations originating from the dorsal column and cerebellum, which ultimately receive their input from the non-stop gravitational transductions derived from postural spinal muscles and joints.  This, as we chiropractors know, can be globally deficient and/or specifically decreased in specific areas.  What a unique and powerful set of lenses through which to grasp the impact of our adjustments.  Brings another level of clinical clarity and sense of awe to just how powerful a well delivered and precise adjustment can be- an approach that is rational, scientific and still embraces the time honoured wisdom of our original principles.

So when I first stumbled upon these concepts, this research and this level of understanding of the brain and nervous system, I wondered to myself what would it look like?  If I could peel away the skin and tissues of a living organism and be left with just a bunch of endless activated synapses and circuits lighting up endlessly like an overly lit up Christmas tree, what would that look like?  Well I'm watching a TED talk by Dr. Henry Markram, director of Blue Brain, a supercomputing project that can model components of the mammalian brain to precise cellular detail and simulate their activity in 3D, and he shows a computer simulation of a living rat's brainstem.  See if you can pick up the bursts of 40 hz oscillations responsible for the binding and therefore perception of sensory stimuli....I was stunned.  

So now for a new twist to the Harvey Lillard story as put forth by my Neurology Instructor, Dr. Melillo.  As you know, Harvey Lillard was a janitor who worked in the same building as Daniel David Palmer back in 1895.  Harvey was deaf and D.D. inquired of the man how this came to be.  Harvey proceeded to explain that it happened all of a sudden while lifting something, he heard a pop in his spine and from that time, he could not hear.  As the account goes, D.D. went to the area of the spine pointed out by Harvey and he performed the first chiropractic adjustment.  Harvey's hearing returned and the rest, as they say, is history.  Palmer, at the time, explained that the hearing returned based on the hypothesis that there was a connection between the spine and nervous system...a segmental connection emphasizing interference to the sensory pathways for hearing.  But what if by increasing the movement of spinal joints and allowing those postural muscles to stretch against the forces of gravity on a continuous basis, Harvey's baseline arousal levels was allowed to increase through the cerebellar, thalamic and spinal pathways.  This, in turn, resulted in an increase in the signal to noise ratio such that the same level of sound that could not be perceived previously, now is better able to summate and be processed.  

Food for thought.

  

The Physics of the Brain- Part 2

"Gimme a beat."


In 1986, Janet Jackson released a song called "Nasty" and the above quote was how she started the song.  For all my musician wanna-be readers out there, "getting a beat" is the quintessential rallying cry for rock groups, orchestras and high school bands alike to begin their path to harmonic and melodic glory.  For those card carrying members of the "rhythmically-challenged" club, think "Ready, Set, Go!" or just your basic "on the count of 3" command.

Now imagine attending a symphony, say the famous Boston Symphony Orchestra, except you notice there is no conductor with his little stick......and all the musicians are blindfolded......and have ear plugs in their ears.  Oh, and one more thing- before they were led to the stage they were told to play whatever chords they wanted at whatever time they wanted.  Now sit back, close your eyes and pretend you're in the front row of that symphony.  How would that experience be?

I just described the brain of a child with autism.  And to a much lesser degree, your brain when it just can't recall the name of a patient you just saw earlier that day, or the last item your wife ask you to pick up at the grocery store. Or, better yet, you can't seem to link or connect the relationship between a dysfunctional spinal segment, its inability to depolarize a population of receptors and the deafferentation effects to the central integrative pathways just two or three synapses away.  Phew!  That was a mouthful.

"Binding" is the term used to describe the above situations.  On our journey to understanding the space-time continuum of the brain, we focus, in this post, on the concept of time as it relates to brain function and how we humans became more dependent on timing connections than physical connections as we evolved from our bipedalling, knuckle dragging days.

Quite simply, as we humans got the rhythmic, synchronous and motor "binding" act of walking down pat, it opened the door to the ability for the brain and nervous system to differentiate and specialize, and with it, this idea of coherence (both spatial and temporal).  The idea that the brain is asymmetrical in its functions (known as lateralization) as an evolutionary exaptation to perfecting upright walking is not new.  All that split brain research done in the 70's proved it so.  However, as a historical side note, this research led to an over-simplification and to the pop psychology phase of "left brain vs right brain" crap.  Brain asymmetry fell out of favour for awhile.  As in any reaction to pop psychology phases, pseudo-intellectual "contrarians" (who exclusively never follow whats "popular") hammered on it incessantly with equally over simplified opposing arguments and unfortunately threw the bath water out with the baby.  Needless to say, functional brain asymmetry, aka lateralization, is an evolutionary and neuroscientific fact.....its just not as simple as you think.

Integration can only come as a result of having differentiation.  Think about it, if you don't have different things than what are you integrating?  An orchestra playing beautiful and harmonious works of art is an integration of "different"talent and  "different" instruments coming together with the lead of a conductor and his "beat".   The musicians are arranged "physically" on the stage in a certain way for a reason but it is their timing that produces such exquisite sound.

Now think about a concept many of you are familiar with, from Dr. Donald Hebb (a Canadian neuropsychologist),

"Nerves cells that fire together, wire together."


Have you ever thought about why it wasn't phrased as, "Nerve cells that wire together, fire together."?  Ahh, did you just have an a-ha moment?  I did.

Now, Chiropractors, imagine those populations of receptors not firing its EPSPs (excitatory post-synaptic potentials) into the cord and up to the brain, especially from one side (which is usually the case).  What will that do to the all critical bottom up development of a still specializing and maturing young brain?  The genes that develop the neurons in the brain are experience dependent, not chemical dependent.  For neurons to work as a team, it helps to have a beat.  The greatest source of coordinated neuronal activity comes from the gravity induced slow adapting muscle spindles and mechanoreceptors of the SPINE.  This oscillatory activity into thalamus (with other sensory input) is the contextual "beat" which binds the information from our senses together and serves as the platform for your ability to sort the signal from the noise.  To finally remember the patients name, the fact that it was bananas your wife wanted from the store and to own and grasp this idea of healthy spinal function equals healthy brain function.......or how bout that autistic child's first words to his mother being "I love you" (true story).

We promote integration (and coherence) with our adjustments.

In the next post, we will continue with our journey of the Physics of the Brain and you'll want to tune in cause I will be putting forth the most plausible explanation of Harvey Lillard's hearing miracle to date (one that I am sure most of you have not yet heard) and telling you about the "greatest chiropractic study never known".

Now gimme a beat, Janet.

Syntropy (pt. 2)- The Physics of the Brain

In the last blog we discussed the fundamental assumption in classical thermodynamics- that structures move in a temporal progression from states of organization to disorganization.  This is known as the state of entropy.  While our high school experiments certainly showed that nothing contradicts the second law of thermodynamics within the realm of stable, closed systems, things are different in open, complex systems.  In complex systems, the direction is typically from disorganized to better organized.  We referred to this process as Syntropy.

Let's dig a little deeper.

Enter, Systems Theory and Systems Neuroscience,  since I, and many brilliant minds in this field (including some MIT and Harvard brains), see this as the future for research and therapeutic application of the Brain and Nervous System.

First, we must postulate.

"The nervous system is a pattern forming, self-organizing, non equilibrium system governed by nonlinear dynamical laws."


This concept of nonlinear governance of systems is not new to those familiar with Chaos Theory and its sub-branch Complexity theory.  There have been proponents of the idea that self organizing systems move towards increasing complexity and integration for years.  However, it is fair to say that most of what we know about the brain and its physiological operation has been discovered using linear methods.  The relationship between the parts and the whole has been a much debated topic (especially among reductionists and vitalists), and the field of Neuroscience is no exception.  Most studies in the past were carried out within either a top-down or bottom-up framework.

The new story of brain physics, with its new "postulatory"set of lenses, takes us on a new pioneering and groundbreaking journey.  This is because the complex behaviour of a dynamic system cannot easily be predicted or deduced from the behaviour of individual lower level entities, which is something chiropractors have been suggesting for years.  Yet now we no longer need to resort to religious entities or intangibilities to try and explain this Syntropic concept.

In open, complex systems (such as the brain) the constituents are interdependent on many levels.  The brain's emergence and evolution is based upon the cooperation and competition among it's parts.  There is bidirectional interaction between parts and the whole.  And then when this open, complex brain interacts with its environment, special things begin to happen.

The environment (which encompasses the outside world and other people) and the perturbations it provides allow the nervous system to show off its remarkable capacity for learning and growth despite being confined to relatively narrow homeostatic boundaries and simple rules.  In fact, it is this confinement where we witness certain brain "parts" gain dominance over others-  we call this inhibition.  Hermann Haken refers to this as "synergetics" or "order parameter"- essentially the simultaneous action of emergence and downward causation.  In this model, emergence through self-organization, as we have said, is bidirectional.

So now imagine the "bottom up" directional development of a child's nervous system interacting with its environment  where we have local to global causation creating novel and emerging dynamics.  As development progresses, we simultaneously create "above down" global to local determination which, essentially, "enslaves" the constituent parts and effectively governs local interactions.  There is no "agent" causing this "order", IT IS self-organized.  It is circular causation or what is known as "non symmetrical reciprocal causality".

It is this learning and growth or adaptive property of the brain where something greater than the sum of its parts can emerge and this "emergence" is thus qualitatively different from the level it springs from.  The evolving nervous system can now adapt its internal structure so that its dynamics can PREDICT more and more effectively  the consequences of the external perturbative forces acting upon it.  This has spawned some interesting papers with regards to intentionality and free will and caused some in the community to call for a reworking or novel approach to its meanings.

As a chiropractor, I am on pins and needles because  we are not only engaged in the understanding of this ground breaking  theoretical and experimental model of the brain but we have the tools and most rational application to bring it to the world and make an even bigger difference than we already have.

In my next post, I'd like to elaborate more on The Physics of the Brain and how it relates to what we do as chiropractors.  Stay tuned.