~ Learning ~
As a behaviorally-trained brain-based clinician with a doctorate in clinical
psychology, learning is a concept that for me, takes center stage. It is the concept at
the very epicenter from which the brain-based behaviorist views, theorizes,
conducts an interprets research, and treats those under their care. Disorders such
as addiction or trauma, for example, are perceived and treated as maladaptive
learned responses to stimuli in the environment. This applies equally to an
individual's behavior as it does to the individual synapses in a human brain. If you
are reading this, you know what learning is; if asked to define it however, it's not
quite so easy.
Simply stated, learning is the acquisition and processing of information, taken in through one or more of the five senses, that through repetition, creates or alters the brain specific to the type of information attained. Seeing something and touching something, or tasting something, are coded differently and routed to different areas of the brain. An interesting example of when this process glitches and goes awry, is the person who is synesthesic.
Synesthesia is an interesting example of a neurological impairment (some might say enhancement) whereby the brain learns to think in unusual ways by associating different senses together. For example, some synesthetes actually associate a sound to a color, or see colors as numbers. Still others might associate numbers with spatial relations such as seeing the number '4' as close by and the number 52 being further away in space then 11. Although there are several interesting theories as to the cause of such unusual perceptual experiences, few would disagree that whatever the cause, synesthesia is a product of a glitch in the brain whereby the coding and processing of information, AKA learning, somehow got its wires crossed. How could that happen? Based upon the basic principles of learning, it makes a lot of sense.
Below we begin a brief tour at the cellular level of the brain, the place where learning occurs.
Below we begin a brief tour at the cellular level of the brain, the place where learning occurs.
The Neuron Doctrine. In 1894, Santiago Ramon y Cajal (pictured on left), the brilliant neuroscientist and nobel prize laureate for his work and discovery on what has come to be known as the Neuron Doctrine, was the first to realize that the brain is composed of individual cells known as neurons (and not a network of reticulum as previously thought), and that the little gaps inbetween neurons, what we now commonly know as the synaptic cleft, are what connect one neuron to another. Interestingly, this discovery was based upon his detailed drawings of the nervous system only made possible by another discovery just a few years prior by Camillo Golgi (with whom he shared the 1906 Nobel prize and who ironically opposed Ramon y Cajal and believed in the reticulum theory). Golgi invented a staining technique that enabled scientists to actually see what a nerve cell and a dendrite looked like, an invention that catapulted the research possible in the brand new field of neuroscience. By soaking brain tissue in a silver nitrate solution thus enabling the viewing of neurons, axons and dendrites, and in combination with Ramon y Cajal's artistic ability, the world had its very first view of the basic building blocks of the brain. Six years prior, Ramon y Cajal published his findings on the law of dynamic polarization, which states that information received in the brain flows in a unidirectional pattern beginning with the dendrites, through the length of the axon, and out the axon terminal into the synaptic space, waiting to be sucked up by a neighboring neuron.
Dendritic Branching. Information is acquired when the brain receives data from any one of our five senses; seeing, hearing, tasting, smelling, and touching. This however is not learning in and of itself, but rather the means by which information is routed to the brain from the environment. Learning begins when the brain, having received the information from the environment, begins to process it. When information is taken in through the senses, and depenent upon the type of information taken in, neurons specialized for each type of information are routed by dendrites (those tree-branch looking things) that in turn, enable the neurons to make contact with one another at the cells' synapse. Repetition solidifies the process. Dendrites branch in response to stimuli acquired through the senses and the processing of that information. It can be said that learning is a function of dendritic branching. In the very brief video below you can actually see what that process looks like. You can see the dendrites begin to branch, the electrical activity that passes up and down the length of the neuron, and finally, the name of each part...
As each dendrite branches and grows, it forms an axon (the long slender stick-like protrusion), and a synapse (at the end of the axon terminals) whereby information is exuded from one end of a synapse as it is taken in by the synapse of another neuron close to it. You can see this clearly in the video below of a greatly enlarged synapse. The substance spilling out of the synapse are little round vessicles that contain a specialized substance called neurotransmitters. These neurotransmitters are teeny microscopic bits of encrypted information that travel along the length of the synapse by way of an electrical charge. There are different kinds of neurotransmitters dependent upon the type of information received. The electrical charge helps the neurotransmitter travel from one neuron to another neuron much like the electrical current that runs through the wires of an
electricity-powered device. And, much like the cord of any electrical device, a fatty substance called myelin wraps around the neuron like a sheath, acting exactly like the rubber coating that wraps around the wire of the electrical cord. As this process occurs, more and more dendrites are formed. The more dendrites that sprout, the more learning can occur. As a person goes through life learning either formally or experientially, the more dendritic branching occurs. The brain of a highly educated person for example, has significantly more dendrites in their brain then a person of lesser education and experience. This can readily be seen on autopsy (should that need ever arise)!
Neurons. There are approximately 100 billion neurons in the typical human brain that wind up making 1,000 trillion synaptic connections, give or take a few, that are split among three different kinds of neurons (motor, sensory, and interneurons).
Notice that in the image below, the cell body is wrapped in purple sausage- looking tubes. These tubes represent myelin,the substance that insulates and protect the neuron. It also enables the electrical current needed by the cell to travel faster in order to deliver the neurotransmitters from one neuron to another quickly. As mentioned, myeli acts much like the power cord of a computer or lamp. The material insulating the wires are usually made of rubber or a similar substance. A
Neurons. There are approximately 100 billion neurons in the typical human brain that wind up making 1,000 trillion synaptic connections, give or take a few, that are split among three different kinds of neurons (motor, sensory, and interneurons).
Notice that in the image below, the cell body is wrapped in purple sausage- looking tubes. These tubes represent myelin,the substance that insulates and protect the neuron. It also enables the electrical current needed by the cell to travel faster in order to deliver the neurotransmitters from one neuron to another quickly. As mentioned, myeli acts much like the power cord of a computer or lamp. The material insulating the wires are usually made of rubber or a similar substance. A
lamp generally has a thin cord since there are few wires to insulate, and it does not take much electrical current to power up the bulb. Your desktop power cord on the other hand, is usually thick and heavy. This makes sense given that there are many wires underneath that thick rubber coating, as there is a great deal of current needed to power up the machine. The thicker the cord, the more wires it can accommodate, and the faster the current can travel. This is similar to what happens in the brain. Occasionally, over time and use, cords can become frayed. When this happens, the electrical current running through the frayed wires, having lost some or all of its insulation, can lose its charge or take longer to travel the length of the cord from power supply to power. Just like the brain. The faster a person can run, the quicker and more abstract a person can think, and the better able someone can accomplish a task, are all signs that the associated neurons and the myelin sheath that surrounds them are in excellent shape; and they got that way through learning.
There are certain diseases, called demyelinating diseases that are formed when the myelin of a cell or group of cells begin to wear away or fray. When this occurs, the electrical charge needed to rapidly deliver information from cell to cell becomes weaker and the information that travels along that cell body, will eventually stop traveling completely and any information from that cell will be lost forever. Multiple Sclerosis (MS) is well-known demyelinating disease. The symptoms of MS vary depending on the type of cells that have been demyelinated. If cells within the visual cortex become demyelinated, loss of vision can occur. Similarly, if cells responsible for certain muscle movements are effected, those muscles may eventually lose their ability to move. It can be said that MS is an unfortunate but prime example of the brain unlearning previously learned information. And as noted in the tab on Neuroplasticity, once the myelin of an axon has worn away, it cannot be repaired and neuroplasticity, a specialized type of learning, can no longer occur.
Want to learn more? You can follow my blogs, take a webinar, seminar, or e-course.
Want to learn more? You can follow my blogs, take a webinar, seminar, or e-course.