Friday, June 15, 2007
In the Chronically Subluxated patient
In the Chronically Subluxated patient the brain is not processing or organizing the flow of sensory impulses in a manner that gives the individual good, precise information about himself and his world.
Energy Use by the Brain
Energy Use by the Brain: Organisms in the natural environment are highly efficient in their use of their available energy, and sometimes even more important, their cooling resources. That is, the use of food and water by organisms is often associated with processes that become sensible when we suppose one or both of these resources are scarce. And scarce they are at the margins, the place where evolution/ natural selection occurs fastest. It is at the interfacial niches of marginal survival that competition is most severe and mutations would be most beneficial, thus leading to higher rates of evolution. Clearly at such places of marginal survivability, energy efficiency will be very important. So we have good reason to expect that organisms are made up of and use energy efficient processes.
In this context of energy , neural processing is rather expensive. The adult human the brain accounts for20% or more of our total energy use and it consumes on the order of 20-25 watts. In young children, whose brains are nearly as large as an adults, the energy use by this organ can account for nearly 50% of the caloric intake.
Current research implies that more than 85% of the energy used by brain goes toward restoring the ion fluxes across neuronal membranes that are the biophysical basis of computation and communication in the neocortex. Thus neural informational processing although perhaps five to six orders of magnitude more energy efficient than man-made computation, is a considerable expense for the organism.
Because of such energy costs, natural selection (or intelligent design for maximal survival) has optimized energy use as well as information processing in constructing the way neurons compute, process, develop, filter, integrate and communicate.
In all of its functions, the brain seeks optimum efficiency, or the path of least resistance. If one particular function is not accessible, the brain will automatically go on to the next most efficient process for doing that particular task. If the second task is not available, it will go on to the third or the fourth most efficient way. Because each alternative process is less efficient, it becomes more stressful and energy expensive
The brain will keep searching for an appropriate processing method, until eventually the activity may become so subconsciously stressful (energy greedy) that the person will choose to give up trying to do the task altogether. If it is a conscious activity, the individual will give up the fatiguing activity. If the process is unconscious, the individual will decrease the energy partitioning to that process, making this unconscious activity minimized, nonfunctional or detrimental to the whole, depending on where the process is located in the physiological hierarchy.
Thalamic Integration and Filtering
Thalamic Integration and Filtering: The thalamus does not passively relay information from the sensory system to the cortex. Rather, via feedback from the cortex and the brain stem, the thalamus controls the type and amount of information that reaches the cortex. Recent scientific findings prove the thalamus plays a role in how the cortex functions. Cortico-cortical communication depends heavily on how messages are integrated, filtered and modified through the thalamus.
The complex cell and circuit properties of the thalamus leave little doubt that the relay of sensory information to the cortex is an active, adjustable and modifiable process. Thus, the full impact of the thalamus recent research has shown is much more than simply controlling flow of information from the periphery and from other parts of the brain to the cortex: it is the most active partner in all cortical computations.
Integration in the thalamus is the sum of different driver inputs (highly prioritized afferents) to produce an output that differs qualitatively from that of any of the inputs. Filtering in the thalamus is the summing of different driver inputs (highly prioritized afferents) to produce an output that differs quantitatively from that of any of the inputs. So if the thalamus is intact, symptoms and dysfunction are the sum (integration and filtering) of different inputs into the thalamus. Symptoms, dysfunction and dis-ease are dependent on thalamic firing. Thus if the chiropractor can change input into the intact thalamus to move the CNS to produce a healthier functional status, the output will be health. The “nerve interference” is on the afferent side.
Neuroplasticity
Neuroplasticity (variously referred to as brain plasticity or cortical plasticity) refers to the changes that occur in the organization of the brain, and in particular changes that occur to the location of specific information processing functions, as a result of the effect of experience during development and as mature animals. A common and surprising consequence of brain plasticity is that the location of a given function can "move" from one location to another in the brain due to repeated learning or brain trauma.
The concept of plasticity can be applied to molecular as well as to environmental events. The phenomenon itself is complex and can involve many levels of organization. To some extent the term itself has lost its explanatory value because almost any changes in brain activity can be attributed to some sort of "plasticity". For example, the term is used prevalently in studies of axon guidance during development, short-term visual adaptation to motion or contours, maturation of cortical maps, recovery after amputation or stroke, and changes that occur in normal learning in the adult. Some authors separate forms into adaptations that have positive or negative consequences for the animal.
For example, if an organism, after a stroke, can recover to normal levels of performance, that adaptiveness could be considered an example of "positive plasticity". An excessive level of neuronal growth leading to spasticity or tonic paralysis, or an excessive release of neurotransmitters in response to injury which could kill nerve cells, would have to be considered perhaps as a "negative or maladaptive" plasticity.
The main thing to know is that even the adult brain is not "hard-wired" with fixed and immutable neuronal circuits. Many people have been taught to believe that once a brain injury occurs, there is little to do to repair the damage. This is simply not the case and there is no fixed period of time after which "plasticity" is blocked or lost. We simply do not know all of the conditions that can enhance neuronal plasticity in the intact and damaged brain, but new discoveries are being made all of the time. There are many instances of cortical and subcortical (thalamic!) rewiring of neuronal circuits in response to training as well as in response to injury.
There is solid evidence that neurogenesis, the formation of new nerve cells, occurs in the adult, mammalian brain--and such changes can persist well into old age. The evidence for neurogenesis is restricted to the hippocampus and olfactory bulb. In the rest of the brain, neurons can die, but they cannot be created.
To review, plasticity is the selective elimination of axons, dendrites, axon and dendrite branches, and synapses, without loss of the parent neurons, which occurs during normal development of the nervous system, as well as in response to injury or disease. The widespread developmental phenomena of exuberant axonal projections and synaptic connections require both small-scale and large-scale axon pruning to generate precise efficient connectivity. This pruning provides a mechanism for neural plasticity in the developing and adult nervous system, as well as a mechanism to evolve differences between species in a projection system.
Such pruning is also required to remove damaged axonal connections or those that are perceived by local mechanisms as not being efficient for the required circuit, to stabilize the affected neural circuits, and to initiate their maturation or repair. Pruning occurs through retraction, degeneration or functional degradation.
To maintain energy efficiency (whether the program is physiological or not), the CNS, through innate intelligence, will actually change the cells themselves!
