The Nervous System & The Brain: The Basic Structure

The Nervous System & The Brain: The Basic Structure Psychology 12

Who are we? What makes us into the people we are today? What separates us from animals? What is the “mind”? Is it simply the grey organ nestled inside every human head—or something more? Is it flesh or spirit? Does the mind control the body or vice versa?

Who are we? To understand the mind and thus people, first, we must look at our biological make-up to determine how we perceive the world and interact with it…

Have you ever experienced a runners high? It’s almost like running is this great friend we both share…Anyways, that’s what I’d like to talk to you about…running as a friend, a companion…in other words, the relationship of running. “WHAT!?” many of you will be saying, “I thought that I was going to learn about how to improve my 10k time.” Go read “Runner’s World” for that. You see, I don’t view running as what I DO or what I AM, but as this thing, this force, that changes me over time… ---from “Running and Me: A Love Story” by Joan Nesbit, 1999

Runner’s High Why does the writer love running so much? One of the reasons may be that people who do a lot of running—especially long-distance running, often talk of an effect called a “runner’s high.” The longer they run, the more tired they get, of course; but at some point, the runners will “push through the wall” and “get their second wind.” Why does this happen?

Runner’s High Why does the writer love running so much? Why does this happen? Endorphins, which are neurotransmitters, produce the euphoria of a runner’s high. As the body deals with a very physically stressful situation—running---the runner’s body reacts to stress.

Question for Discussion… How do you think the nervous system will react? What other types of physically stressful situations may the human body encounter?

How the Nervous System Works The nervous system controls your emotions, movements, thinking and behaviour. Structurally, it is divided into two parts—the central nervous system [CNS] ( the brain and the spinal cord) and the peripheral nervous system [PNS] (the smaller branches of nerves that reach the other parts of the body.

How the Nervous System Works All parts of the nervous system are protected: the brain by the skull and several layers of sheathing, the spinal cord by the vertebrae, and the peripheral nerves by layers of sheathing.

How the Nervous System Works The bony protection of the spinal cord is vital. An injury to the spinal cord could prevent the transmittal of messages between the brain and the muscles, and could result in paralysis.

What is the Nervous System? http://www.youtube.com/watch?v=NL1S0AhYyFw&feature=relmfu http://www.youtube.com/watch?v=sq9qfSusNmA&feature=related http://www.youtube.com/watch?v=sjyI4CmBOA0&feature=related

This is a Neuron The brain uses networks of these neurons, so small that 30,000 of them can fit on the head of a pin - to process information

This is a Neuron Your brain has about 100 billion of them! They help you think, learn, move and experience your world.

This is a Neuron Neurons depend upon support cells called glia. Glia help to insulate, nourish and protect neurons. There are about 9 glia for every neuron.

This is a Neuron Messenger Molecules Neurons communicate with each other. Within the brain there is a constant “chatter” of cells as they communicate with each other using a language of electrical impulses and chemical signals.

This is a Neuron Messenger Molecules Information “travels” when electrical impulses within a neuron trigger the release of a burst of messenger molecules (called neurotransmitters or NTs) from the end of the neuron. The NTs then flow into a tiny space called a synapse. .

This is a Neuron Messenger Molecules The NTs within the synapse then contact the next neuron, triggering another electrical impulse and the continuation of communication along the next neuron. FYI [the synapse is less than one millionth of an inch wide and is filled with fluid that transmits the chemical from one neuron to another]

This is a Neuron Building Information Highways Neurons connect with each other to form neural networks that serve to carry information from one area of the brain to another. A typical neuron forms 1000 to 10,000 synapses with other neurons, thus forming a neural network. Electrical impulses travel across neurons at speeds up to 400 miles per hour. We can instantaneously tap into a memory, “get” a joke, feel inspired - all because of these neural networks. .

Neurons Chemical-electrical signals travel down the neurons through the dendrites much as a flame travels along a firecrackerfuse. The main difference is that the neuron can fire (burn) over and over again, hundreds of times a minute.

Neurons Transmission between the neurons, or nerve cells, occur whenever the cells are stimulated—the neuron fires according to the all-or-none principle (when it fires, it fires at full strength).

This is a Neuron REVIEW: The neuron receives messages from other neurons on its dendrites Messages are transmitted down the axon and sent out through axon terminals

The Neuron Connection Neurotransmitters Chemicals released by neurons, which determine the rate at which other neurons fire Neurotransmitters bridge the gap (synapse) between one neuron and the next.

Neurotransmitters There are many types of neurotransmitters Norepinephrine Endorphin Acetylcholine Dopamine Serotonin

Neurotransmitters Neurotransmitters Norepinephrine: involved in learning and memory Endorphin: inhibits pain Acetylcholine: movement and memory. An undersupply is associated with paralysis and Alzheimer’s disease

Neurotransmitters Neurotransmitters; Dopamine: Learning, emotional arousal and movement. An oversupply is linked to schizophrenia—an undersupply is linked to Parkinson’s disease Serotonin: cognitive functions—memory and learning. It also regulates intestinal movements and mood, appetite, sleep, as well as muscle contraction. An undersupply of serotonin and norepinephrine may result in depression

This is a Neuron Your fingers are dendrites Palm is a nerve cell Your arm is an axon

How do drugs/alcohol affect the brain? Drugs interfere with neurotransmitters in the brain. 'mind-altering' drugs change our interpretation of the world, our behaviour, and our mood. For example, cannabis, affects neurons releasing acetylcholine, noradrenaline and dopamine LSD mimics serotonin action in the brain, which seems to explain its hallucinogenic effects.

Neurons & Alcohol Every time someone gets drunk, they kill off nerve cells—similar to the picture below (look at the dendrites)

The Neuron Connection A New Brain Every Day Your brain is “magni-ficient!” Magnificent, and at the same time, efficient, your brain changes and grows to help you function in your life. Your networks are the “behind the scenes” wiring that allow you to express your unique qualities.

Railway tracks or Wildflowers You might have passed by old railroad tracks with wildflowers growing nearby. In the past: believed that brain connections were like railroad tracks – basically permanent, with no significant growth and development during adulthood. In aging-- neurons and connections would fade away like old defunct railroad tracks. This view left little hope of reversing memory loss or building up cognitive reserves to promote brain health in aging.

Railway tracks or Wildflowers Learned that neurons are more like wildflowers rather than railroad tracks. Found that new neurons sprout throughout life. The brain naturally develops by balancing periods of exceptional growth - called “blooming” - with periods of trimming back or “pruning.” But things we do in everyday life – exercise, learning something new – also promote sprouting of new neurons.

Neurons How nerve cells work: http://www.youtube.com/watch?v=c5cab4hgmoE&feature=related http://www.youtube.com/watch?v=CMnDiepv5Os&feature=related http://www.youtube.com/watch?v=NL1S0AhYyFw&feature=relmfu

Learning Activity Draw and label the parts of a neuron, and describe the parts Complete questions 2 & 5 on page 159.

Phrenology… Luckily, we’ve come a long way from this theory… But—it did encourage scientists to examine the role of the brain in human and behaviour. Remember early psych methods… Studying the bumpson a person’s skull to determine that person’s intellect and character traits…

Brief History of Brain Research Dr. Broca (resp. for Broca’s Area) A patient of Dr. Broca suddenly lost his ability to speak—but otherwise normal For 30 years, he could only utter one syllable “Tan”—became known as Mr. Tan. Dr. Broca performed an autopsy on his brain—what he found stunned scientists.

Brief History of Brain Research An area of the brain, as large as an egg had completely deteriorated Since Tan’s behaviour was normal, this meant his speech was controlled specifically by the diseased area

Brief History of Brain Research Broca had new scientific evidence that contradicted prior knowledge of the brain: every part of the brain controls every kind of behaviour (prev. understanding) In fact, Tan showed this idea to be wrong---the control of one specific behaviour, like speech was localized in one specific area/part of the brain.

Brief History of Brain Research Mapping Behaviour in the Brain: 1870 France went to war with Germany…two German doctors roamed the battlefields for dying men…looking for soldiers who skulls were blown open from gunfire. They used an electrically charged mental probe which applied to the surface of exposed brain…

Brief History of Brain Research Found: Stimulation to the same brain area always resulted in movement of the dying man’s arms and legs. This confirmed Broca’s findings & created a new research tool for understanding the brain

Brief History of Brain Research Electrical probes to map the location of behaviour in the brain—discovered that our psychological experiences are controlled by nerve cells in 4 sections or lobes of the brain’s cerebral cortex… Each lobe exists on both sides of the brain—because the brain’s cerebrum is divided into two identical hemispheres.

Brief History of Brain Research Dr. Penfield (1940s) He devoted much thinking to the functioning of the mind, and continued until his death to contemplate whether there was any scientific basis for the existence of the human soul

Brief History of Brain Research Dr. Penfield (1940s) Electrical probes to damaged brains of patients Stimulated movement and the senses, but also memories and actual mental experiences Some saw themselves at concert halls, games, heard music, saw neighbours, and heard people calling them…

Brief History of Brain Research Dr. Penfield (1940s) His patients weren’t physically perceiving real games or listening to music—but they had purely mental experiences His experiment stimulated mental behaviour... We’ve learned about the brain’s role in behaviour—but what does this experiment tell us of the mind?

Brief History of Brain Research Will we ever understand the mind/body question…? Modern psychologists study the physical structure and our behaviours—perhaps this will lead us to understanding the “mind”

Brain & Behaviour Charles Whitman --Killed wife and mother & 47 people from top of tower --People thought he must be crazed, but those who knew him said he was normal…

Brain & Behaviour Charles Whitman --Wrote a letter 24 hours before killing spree. He complained of headaches and weird thoughts and wanted an autopsy done after his death. --Found he had a tumor the size of a walnut pressing down on an area in his brain that is responsible for aggression.

Brain & Behaviour Charles Whitman His mental illness could have been physical. His apparent healthy “mind” could only wander helplessly while his diseased body destroyed it. Lets look at the brain in our understanding of behaviour…not the “mind”

A Tour of the Brain We begin our exploration of the brain at the lower end, where the spinal cord joins the base of the brain, and then continue upward toward the skull. Note that as we move from bottom to top, “lower,” basic processes like breathing generally give way to “higher,” more complex mental processes.

Tour of the Brain The brain is the control center of the body. Made up of dense "grey matter" consisting of complicated networks of interconnected neurons the brain can be superficially divided into three main parts: the hindbrain, the midbrain and the forebrain.

Tour of the Brain • Also, the large section labeled as the BRAINSTEM includes parts of all three of these3 sections and helps regulate reflex activities important to survival (ie, heartbeat and respiration)

The Nervous System & The Brain: The Basic Structure