ALPHABETICAL BRAIN™ VOCABULARY DETAILS Flash Card #2 WHAT ARE YOUR "NEURONS" AND WHY ARE THEY SO IMPORTANT? Your NEURONS are specialized brain cells that are able to carry and send "ionic impulses" (electrical signals) all around your brain and also up and down your body. Your Neurons are the very small 100 billion nerve cells of "gray matter" in your brain and spinal cord, which are the smallest self-contained building blocks of your brain. These microscopic brain structures, which make up about 20% of your brain cells, make possible your ability to communicate with different parts of your body and with other people. They SEND or RECEIVE ionic impulses (electrical signals) to and from your muscles and senses and internal organs ONLY in one direction! In addition, all of your neuron cells are connected to each other by your SYNAPSES, which relay electrical signals through an electrochemical process known as "potentiation" or LONG-TERM POTENTIATION. The neuroanatomy of learning and memory: (1) There are many kinds of neurons. (2) Motor neurons convey motor ("motion") information. (3) Sensory neurons convey sensory information. (4) Interneurons modulate the activity of other neurons. "All neurons have a basic structure that consists of a ‘cell body' (soma), ‘dendrites,' and an ‘axon.' The ‘soma' or cell body contains the genetic material (DNA) within the nucleus. Neurons develop from ‘stem cells' and cannot divide. But since the genetic material is required to maintain and regulate neuronal function, which is ‘electrochemical signaling' ('neurotransmission' = receiving and sending information), it is essential for establishing the ‘ionic gradient' (membrane potential). The ionic gradient is the electrical charge between the inside and outside of the neuron."(pages10-11) "A change in the membrane potential of a sensory neuron is signaled as Na+ floods into the cell and K+ floods back out of the cell in an attempt to restore the ionic gradient. The flow of ions across the neuronal membrane produces a change in membrane potential called 'depolarization.' When it is strong enough, depolarization of the dendrite produces a wave of electrical current that passes into the cell body where an ‘action potential' is initiated and sent along the neuron's axon." (pages10-11) "For example, the simplest common muscle reaction involves sensory neurons being activated by heat or pain 'synapse' (as a verb) onto ‘interneurons' in your spinal cord that make direct connections or 'synapses' (as a verb) onto the motor neurons that activate the appropriate muscles to retract your hand or arm from the heat or pain!" "This simple 'neuronal circuit' [sensory neuron to interneuron to motor neuron to muscle] is called a 'withdrawal reflex' as it does not require any conscious activity from your brain to make the hand or arm move away (retract) from the heat or pain." (page 11) "Such a simple neuronal circuit is missing much of the 'synaptic complexity' that neurons in the brain must deal with in regulating brain function. However, this simple reflex illustrates the electrochemical impulse that all neurons use to receive, process, and propagate information throughout your nervous system." (page11) Book Source = LEARNING AND MEMORY by Andrew Hudmon. 2006 This phenominal process of the "ionic exchange" of potassium and sodium isotopes is known as NEUROPLASTICITY (or "synaptic plasticity"). It makes possible your ability to LEARN and REMEMBER anything and everything! Synaptic plasticity is the irreducible essence of biological and psycho-social change. It gives you the freedom to change your mind about anything and to change your body's skill-sets. Of course, the process depends upon the help of all the other parts of your brain and nervous system as you make decisions and create new ideas and learn new habits. In short, for the first time in human history, scientific knowledge about the way your NEURONS and SYNAPSES work together can explain what makes possible your self-awareness and creativity as a person who is now more conscious of your own brainpower! Go to: FACT CHECKER Return to flash card #2: NEURONS Return to flash card list: LIST OF FLASH CARDS