This section is to familiarize you with the basic structure of the brain and gain a basic understanding of its functions. There isn’t enough space to go into very much detail in this course, but a basic understanding is necessary. As you go through this information, you will find constant references to different portions of the brain and I want you to be comfortable with its function and structure.
Everyone knows that the brain is the master computer for the body; it regulates all of the functions that take place in the body. The circulatory system, the lymphatic system, respiration, digestion, the immune system, and, of course, the nervous system are all controlled by the messages processed in the brain. In general, the brain is divided into three main portions: the action portion, the emotion portion, and the thinking portion. I will break down each one and explain basically what each portion is responsible for. Please understand, the brain is a highly complex and beautiful thing. Simplifying it is difficult, but too much detail and I may lose your attention. If you want more detail I suggest you get the “Human Brain Coloring Book” by M.C. Diamond/A.B. Scheibel/L.M. Elson. Yes, it is a coloring book, and that is an incredible way to learn. Actually, the brain likes to learn things in a way that it can get its hands into. For now, I will stay with the basics.
The Action Portion
The action portion of the brain consists of the cerebellum and the brain stem. Among other things, the brain stem houses the medulla oblongata, the mid brain, and the pons.
This portion of the brain is responsible for many of the body’s automated functions, for example: regulating heart rate, blood pressure, breathing, coordination, and transferring information between the brain and spinal cord. It is responsible for motor control and is the home of protective reflexes-your fight or flight and conserve or withdraw responses. It’s the power behind the brains electrical system.
The cerebellum is also linked to attention and language. It is very important to note that the Reticular Activating System (RAS) is housed in the pons portion of the brain stem. This is the portion of the brain responsible for setting the “volume control” in your life. It sets your introversion/extraversion ratio and will adjust this volume depending on the amount of stress you are under. This is a critical part of the Brain Personality Connection; the part of the brain that regulates our level of wakefulness. It is also worth noting that the RAS, when affected by some type of stressor or anxiety or when the fight/flight mechanism is activated, will engage to raise our level of alertness. This allows us to see more details than we would normally see; picking up on things we may not normally notice. This allows us to process and decide what our next move should be. It is the major communication pathway between the anterior brain lobes and energy reserves in the brain stem. I will discuss this portion more when covering the unit on Introversion/Extroversion ratios.
The Emotion Portion
Primarily, the emotion portion of the brain consists of the limbic system and the corpus callosum. The limbic system is often referred to as the “emotional brain” and it contains the thalamus, hypothalamus, amygdala, and hippocampus. Emotions are generated here and are especially important in the amygdala. The limbic system is the collective name for structures in the human brain involved in emotion, motivation, and emotional association with memory. Two additional facts about this portion of the brain are: (1) it can process information up to 80,000 times faster than the thinking portion and, (2) it has more neural connectors to the right hemisphere than the left. (Do you ever get flustered when trying to say something while experiencing a deep emotion? This is why.) I will delve into this in more detail in the unit on Brain Quadrant Dominance.
The amygdala plays a key role in the processing of emotions; it is linked to both fear and pleasure responses. It is also responsible for the fight or flight, and conserve or withdrawal actions in the brain. It is located just in front of the hippocampus. Information is collected from the senses and sent here to be assessed for significance. If there is a threat, the message is sent out to the body, producing any physiological changes that are necessary. All of this happens BEFORE the information is routed to the frontal cortex for cognitive processing.
Conditions such as anxiety, autism, depression, post-traumatic stress disorder, and phobias are suspected of being linked to abnormal functioning of the amygdala, owing to damage, developmental problems, or neurotransmitter imbalance.
The hippocampus is involved in forming, organizing, and storing of memory. It is particularly important in forming new memories, and connecting emotions and senses (such as smell and sound) to memories. It also acts as a memory indexer by sending memories out to the appropriate part of the cerebral hemisphere for long-term storage and retrieving them when necessary.
The thalamus serves as a relay station for impulses traveling to and from the spinal cord, brain stem, cerebellum and cerebrum. It has an important function in directing sensory input to the appropriate place in the cerebral cortex. Sensory input from the body (i.e. the eyes, the ears and other senses-except for smell) pass through the thalamus.
The hypothalamus links the nervous system to the endocrine system by synthesizing and secreting neurohormones (often called releasing hormones) to control the secretion of hormones from the anterior pituitary gland. It also controls body temperature, hunger and thirst, and circadian cycles. This next point is extremely important: hormones that come from this portion of the brain influence and alter immune system function! This is why there is an undeniable connection between your emotions and your immune system. The portion of the brain that is responsible for processing and regulating emotions is also the part that controls the immune system. I will discuss this connection in much detail in unit 8.
Another interesting note about this portion of the brain is that the olfactory bulb lives here. Stimuli from all of the other senses are routed through the thalamus and then sent to the appropriate portions of the cerebrum for processing. However, the sense of smell is different. The incoming information is actually processed directly in the emotion center of the brain. This is why smells can invoke deeper memory recall than any of the other senses. It also explains why aromatherapy is effective in bringing on a feeling of calm and relaxation.
Research has been done on testing and smell. An interesting test was conducted in a school: a certain smell was introduced into a classroom while the students were studying a subject. Then, when it came time to test the students on the same subject, some were tested in a room where the smell was reintroduced and some were not. The group that had the smell reintroduced during testing had higher scores than those that did not. Scientists are looking into and testing the effects of smell related to helping individuals with memory loss to recall previously lost information. Don’t you just love the way that understanding the brain explains so many things!?
The Thinking Portion
This is the cerebrum. It is the home of cognitive thought and makes up 80% of what we call the brain. It contains eight lobes (ten, if you count the prefrontal cortexes separately) that are naturally divided by fissures in the brain. There are four lobes in each hemisphere.
The first of the main lobes of the cerebrum are the anterior lobes, which include the prefrontal cortex and motor cortex. These play important roles in personality, emotion, executive control, language (especially the left hemisphere), movement, planning, and consciousness. They account for roughly 50% of each cerebral hemisphere.
Just behind the frontal lobes lies the parietal lobe. It processes every message coming in from the sensory systems, except for smell–which is processed directly by the limbic system. It is primarily responsible for sense of bodily position.
Next is the temporal lobe. This portion of the brain contains the areas involved in hearing and understanding speech, especially in the left hemisphere. It also contains the connections to the hippocampus and amygdala. Remember, these portions are important for learning, memory, and emotion. The temporal lobe is also connected to integrating our inner experience and helping us to have a sense of identity.
The last lobe is the occipital lobe. This portion of the brain is the visual processing center. What you see is deciphered in this section.
Together, all of these lobes control the physical aspects of our body: sight, hearing, motor reflexes, touch sensations, speech, and so on. Here is where we process all of the information that comes flooding in from the sensory systems. This is where we create, fantasize, imagine and innovate. It is where we track details in our lives and where we store some of the memories that the brain decides we need and some that we wish we didn’t have.
So much research is being done on the cerebrum. This is where the information regarding energy expenditure and thought processes is coming from. Here is where they are able to see how one subject can process a task and spend far less energy (glucose burned) than another subject. It is primarily this part of the brain that I will delve deep into in the unit discussing Brain Quadrant Dominance (BQD).
In order to have thought, we must have neurons talking to one another. So let’s discuss this amazing process called thought.
These are the backbone to thought. A stimulation of thought (incoming message from the sensory system or from another neuron) fires an electrical impulse in the neuron which sends a charge out of its axon to the dendrite of the next neuron. There are different types of neurons in the brain that have different jobs. It is estimated that there are more than 100 billion of these little guys in our 3 pound brain. These are supported by several times as many glial cells. Glial cells form myelin, and provide support and protection for neurons in the brain, and for neurons in other parts of the nervous system; such as, in the autonomic nervous system.
The potential connections between these cells is incomprehensible. Each neuron may have anywhere from 1 to 10,000 synaptic connections to other neurons. This means the number of possible different patterns of connections =40,000,000,000,000,000! Yes, that many! Another mind-blowing thought: a minute piece of the cerebrum, the size of a coarse grain of sand, contains about 100,000 of these cells.
We know that it takes an electrical impulse to transmit information from one neuron to the next. Recent scientific research shows that the speed at which this happens is from 1 to 150 mph. But, in the area of your brain in which you have an energy advantage you can transmit information much faster: up to 400 mph.
It is important to keep in mind that challenging mental activity helps to grow dendrites and helps to keep the neurons stretched out, narrowing the synaptic gap. If you don’t work and exercise brain circuits, the connections will not adapt and change, and will slowly weaken, and some will be lost. A brain that is “well-toned” often has more blood capillaries and Glial cells, providing a better supply of food and oxygen to the brain. The result is a healthy brain that has better recall and reduces the risk of getting brain diminishing diseases like dementia and Alzheimer’s.
I have to include in this unit an amazing fact: the brain begins its development by the fourth day after conception! Before most women even know that they are pregnant, this brain is growing at an amazing rate. This incredibly rapid growth continues through the early years of life. I will discuss the brain of children more in unit 6.
Hopefully, this information on the history of brain research and brain anatomy has given you an amazing look at this wonderful, and most intriguing part of the human anatomy. I will now move on to the Brain Personality Connection; the way that this incredible mass of neurons is ultimately responsible for so much of who you are and why you do the things the way that you do. Open your mind and prepare to be amazed.