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Learning and the Brain


kamurj

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Excerpted from
Creating Emotionally Safe Schools: A Guide for Educators and Parents
By Jane Bluestein, Ph.D.

Most of us begin life with the neural networks necessary for seeing, hearing, speaking and moving already in place. Along the way, we develop the networks we need to do things like read, add fractions, speak a second language, rebuild a carburetor or play the violin. How does this happen? Our brains contain about 100 billion nerve cells, or neurons. These neurons are specifically designed to send electrical messages throughout the body. They can transmit between 250 and 2,500 electrical impulses per second, sending them along an axon and across a synapse (the space between one neuron and another), to the thousands of dendrites (or branches) of a nearby cell. There are 1,000 trillion connect points between the neurons, with the number of potential pathways estimated to be more than 100 times the total number of atoms in the universe! This is truly a free-form network, "making all information within the brain available at any time from any point."

While most of our neurons are with us at birth, neural organization is pretty limited in the beginning. But as educator Robert Valiant maintains. "It appears that learning consists of the growth of neural connections." Growth in the brain, from one pound to three pounds over the first twenty-one or so years of life, occurs as the brain adds dendrites and glial (supporting) cells. From birth on, and throughout our lives, our interaction with the world offers stimulation to our brains through our senses and our movements. This stimulation causes new dendrites to grow and new connections to form, although there are many more connections in a child's brain than in an adult's. (Around puberty, the growth rate begins to slow and a process begins by which pathways most often used are secured while those no longer useful are eliminated.)

As cells communicate with one another, neural pathways are formed and new connections are made. "When we first learn something, it is slow going, like beating a path through untraveled terrain," claims neurophysiologist and educator Carla Hannaford. However, continual use of these pathways strengthens them, turning them into "superhighways." and making certain patterns of thinking, knowing or behaving easier and more automatic. This process is aided by a layer of myelin, the fatty insulation along the axon, which builds up as neurons are used over and over, increasing the speed of nerve impulses across that cell. We see evidence of this process as we practice a particular skill: The more practice, the more myelin, and the more smooth and automatic the behavior. According to Hannaford, "The process of nerve cells connecting and networking is, in reality, learning and thought. As associations are made and information is synthesized, pathways become complex networks"; these networks are further altered by new experiences and stimulation.

To some degree, the myelin "is laid down around the axons in genetically predetermined patterns." However, different experiences create different patterns of myelination in different individuals, accounting for variances in talents and abilities between individuals. This is what makes our jobs as educators at the same time so interesting and challenging. As educational researcher Claude Beamish describes, "Since the brain is developing or myelinating over a period of so many years, teachers are dealing with students who have brains that have differing levels of development."" If we're only teaching to one type of pattern, what happens to the kids whose development and neural circuitry leave them out of this group?

Students will also vary in their sensitivities to sensory data-information in the environment that makes its way into perception and awareness. These sensitivities will be discussed in various places throughout this book, but for now, suffice it to say that in any learning situation, there is more than just the lesson being presented or the book being read that is getting through to the brain. There are sights and sounds, odors and physical sensations, background and foreground, that can distract or enhance concentration. In addition, many students are especially sensitive to the emotional energy in a classroom, particularly that which is subtly broadcast by the teacher's emotional state. These students can sense tension, impatience and hostility, or enthusiasm, delight or calm in others, and may be particularly adept if they come from a background of trauma or abuse, where this hypervigilance is a practiced survival skill. This element of the emotional climate in a classroom can have a strong impact on the degree to which factual information can be processed, retained and recalled.

With our senses picking up an estimated forty thousand bits of information per second (on average and over time), we'd never be able to focus on anything if our brains didn't have a built-in screening mechanism in the form of the perceptual register (the RAS or reticular activation system). This device "monitors the strength and nature of the sensory impulses and, in just milliseconds, uses the individual's experience to determine the data's degree of importance." The less-important data gets blocked, as when we are able to sleep or read despite nearby highway noises. Our brains are constantly sifting data, bringing the more important elements into our consciousness for further processing, storage and recall. The more important data that gets through this filtering process goes on to what is actually another filtering system: short-term memory. One of two temporary memories, short-term memory operates subconsciously, holding information for about thirty seconds for additional evaluation. If personal experience deems the data significant, the information moves to the next level, working memory, for conscious processing. If unimportant, the incoming signal is dropped from the processing system and stays in the background, out of our conscious awareness and, because it has not been stored, is unavailable for later recall.

Where educator David Sousa represents short-term memory with a clipboard, he uses an image of a work table to illustrate working memory, indicating a place where we can work with a limited amount of information for a limited amount of time, after which the data will either go into long-term storage or be dropped from memory. Getting information into long-term storage for retention and later recall is one of the more important missions for most educators. And yet, for this to happen, the information has to not only make sense, but also has to have some personal relevance or meaning for the student in order to be integrated into understanding. New information has to connect somewhere. Cognitive scientist Stephen Kosslyn states that data in working memory requires "an interplay between information that is stored temporarily and a larger body of stored knowledge," that is, long-term memory. Decades ago, even certain proponents of expository teaching recognized the need for an "intellectual scaffolding." a place of previous personal knowledge and experience on which individuals can "hang" new information. The process requires the help of the hippocampus, down in the limbic system, which converts "important short-term experiences into long-term declarative memories that are stored in the cortex." If you remember, the hippocampus adjoins the amygdala, which, in this instance connects the emotional dimensions of a learning experience when new information is transferred into long-term storage. Therefore, even the most factual learning relies on the "emotional brain" for encoding and transfer to the "thinking brain." In fact, without the element of emotion, most new information will not remain in storage in the brain for long.

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