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How is the Nervous
System
Organized?
Chapter 3
Neuroscience
Module Objectives
What is the Nervous System?
What are the 3 divisions of the brain?
‐ Hind-brain
‐ Mid-brain
‐ Forebrain
Discuss how these structures
influence behavior
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Have you heard the
expression “Information is power?” Nowhere is this
truer than in the human body. Without information,
we could not survive.
Neurons within our nervous system must take in sensory information
from the outside world and then decide what to do with the
information.
What is the Nervous System?
The Nervous System is the body’s main processing
system for information.
This consists of structures and organs that facilitate
electrical and chemical
communication in the body.
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The Nervous System
Central Nervous System (CNS)
‐ The brain
‐ The spinal cord
Peripheral Nervous System (PNS)
‐ The main function of the PNS is to connect the CNS to the limbs and organs
CNS-Spinal Cord
The spinal cord transmits signals from the sensory organs,
muscles and glands to the brain.
‐ Controls reflexive responses
‐ Conveys signals from the rest of the body
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The spinal cord is like a communication
superhighway
between the brain and the rest of the
body.
Spinal cord communication
Communicates with the body below the head through sensory and motor
neurons
Sensory neurons (afferent neurons)
‐ Carry information about touch, pain, and other senses from the periphery of the body to the spinal cord
Motor neurons (efferent neurons)
‐ Transmit impulses from the central
nervous system to the muscles and glands
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Did you know…?
There are about 3 million miles of axons in the human brain
Information travels in the nerves at speeds up to 268 miles per
hour!
How much do you know about YOUR brain??
Structures of the brain
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What observations can you
make about the brain?
Looking at the Brain
The exterior covering (cortex) of the brain is wrinkled which
increases the surface area of the brain
The brain is divided into 2 hemispheres
‐ Right and left hemispheres
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The hemispheres of the brain are connected
The Corpus Callosum connects these hemispheres and allows
communication from one side of
the brain to the other.
Corpus Callosum
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Damage to the Corpus Callosum results in two independent brains in one skull
Split brain patients allowed researchers to discover
“hemispheric specialization”
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What does a spilt-brain patient look like?
Review the following video and
make some observations
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Split Brain Research
This research showed that each hemisphere of the brain is
specialized
‐ The right brain is associated with musical ability, spatial and drawing tasks
‐ The left brain is associated with speech and language.
Hemispheric Specialization
Left Brain
• Controls Right Side of Body
• Right Side Visual Field
• Speaking
• Reading
• Logical Thinking
• Analytical Skills
• Sequential Processing
Right Brain
• Controls Left Side of Body
• Left Side Visual Field
• Spatial Processing
• Facial Recognition
• Music
• Emotional Expression
• Holistic Thinking
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Want to play the Split Brain game?
http://nobelprize.org/educational_games/medici ne/split-brain/about.html
Take the Wagner
Preference Inventory now!
This quiz will help determine which side of your brain is most dominant. It can be found in the
Module 2 notes folder.
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How are these brains
different?
Why are they different?
More recently evolved animals have a larger proportion of the brain taken up by the cerebral cortex.
The cerebral cortex, made up of four lobes, is involved in many complex brain functions including:
‐memory
‐perceptual awareness
‐"thinking”
‐language and consciousness
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Does bigger mean smarter?
NO…
larger brains have nothing to do with
intelligence.
Did you know…
The brain of Albert Einstein weighed 1,230 grams. This is far below the average brain weight of 1,400 grams
The brain of an elephant weighs about 4.78 kg (10.5 lb). An adult human brain weighs about 1.4 kg (3 lb)
The heaviest human brain ever recorded weighed 5 lbs., 1.1 oz (The Guinness Book of World Records, 1997).
The total surface area of the cerebral
cortex is about 2500 sq. cm (~2.5 sq. ft).
It is estimated that there are 60 trillion
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Three Divisions of the Brain
‐ Hindbrain
‐ Midbrain
‐ Forebrain
The Hindbrain
This is the most primitive division of the brain.
The structures in the lower brain tend to be responsible for basic, reflexive functions.
Includes the cerebellum,
Pons, and medulla
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The Hindbrain
The Medulla is the most
primitive and lowest portion of the hindbrain (Part of the brain stem).
‐ It controls basic body functions- heart beat, digestion and
breathing.
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Pons- provides link
(“bridge”)between the medulla and the cerebellum and rest of brain
‐ is involved in respiration, movement, sleeping, waking, and dreaming.
Cerebellum- “Little brain” – attached to back surface of brain stem.
Influences balance, coordination and movement
‐ Allows you to walk a straight line
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Where do complex thought
and behavior come from?
True or False?
We Only Use 10% of
Our Brain
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True or False?
We Only Use 10% of Our Brain False!
This is a Psychology Myth…we use
all of brain most of the time.
Have you ever seen a Kung-Fu movie?
What is most obvious
about a movie that has
been dubbed into English?
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The language doesn’t match, right?
Imagine if you had to go
through life inside a Kung-fu movie? If your midbrain was damaged it would effect
your ability to process
auditory information.
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The Midbrain
• The midbrain helps us orient our eye and
body movements to visual and auditory stimuli
‐ Coordination of visual and auditory reflexes
• The reticular formation (RF) runs through the hindbrain and midbrain.
• This finger-shaped structure filters incoming sensory information and alerts the higher brain centers to important events.
The Forebrain
This the largest, most
complicated and most advanced brain division.
This area of the brain is associated with complex thought and behaviors:
‐ The ability to concentrate,
elaboration of thought, judgment and inhibition.
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Forebrain
The Thalamus is a large structure of
forebrain that acts a routing station or
air-traffic controller.
Processes sensory
information from the CNS before it
reaches the cerebral cortex
The Hypothalamus is a pea- sized structure that controls many complex behaviors
such as eating, drinking and
sexual activity.
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This small structure regulates a variety of complex
behaviors. If you have
trouble remembering what this structure does try this…
The FOUR F’s…
Food
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Fight
Flight
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And…Ummm….
(Fornication?)
Where do my emotions come from?
The limbic system is an interconnected group of structures that are especially significant in emotions, memory, and social behavior.
‐ This is referred to as the “pleasure center” of the brain
The limbic system also includes the hippocampus and amygdala
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The Limbic System
Amygdala
Can pleasure take us over?
YES! Research has shown that rats who received electrical stimulation will repeatedly press a lever which activates this region-producing
pleasure (Olds & Milner, 1954).
‐ The rats will choose to press the bar in preference over food and water,
eventually dying from exhaustion!
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Watch the following clip!
Recent research
suggests that there is a link between addictive
behaviors and the stimulation of these areas (Volvow et al.,
2002).
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Cerebral Cortex
The cerebral cortex is responsible for the most complex mental activities including learning, remembering, thinking, and consciousness
This area is made up of four lobes:
‐ Occipital Lobe
‐ Parietal Lobe
‐ Temporal Lobe
‐ Frontal Lobe
Four Lobes of the Brain
Frontal Lobe
Temporal Lobe
Occipital Lobe Parietal Lobe
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The Occipital Lobe
“Eyes in the back of your head”
Responsible for vision and visual
perception
Parietal Lobe
Parietal Lobe is the area that is specialized for the body senses and body image
The parietal lobe is involved with processing information related to:
‐ Touch
‐ Pain
‐ Temperature
‐ Awareness of the location of body parts
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Includes the Primary Somatosensory Cortex,
a band of tissue on the front of the parietal
lobe
Each area of the primary somatosensory cortex
receives information about
touch in different body areas.
What areas if the body have the most cortex devoted to them?
Sensory Homuncul
us
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As you can see from the previous page the
amount of cortex that is devoted to each body
part is not equally distributed
Larger areas are devoted to touch in the most sensitive parts of the body such as lips and hands.
Smaller areas are devoted to touch in less sensitive parts of the body such as the back and abdomen.
Aren’t you glad your
Somatosensory cortex
doesn’t match the outside?
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Temporal Lobe
The main processing area for hearing Is the main processing area for some of the complex aspects of vision
‐ Such as face recognition and motion detection
Involved in aspects of learning, memory, and emotions
Frontal Lobe
Includes the Primary Motor Cortex,
which controls fine movements such as hand and finger movements
Each area of the primary motor cortex controls a different part of the body
‐ Larger areas are devoted to precise movements of the tongue and fingers
‐ Smaller areas are devoted to movements of the shoulders and elbows
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Once again,
notice the areas of the body that have more motor
cortex devoted Motor
Homunculus
If you want to see this in action try the following.
Wiggle your fingers as fast as you can. Now wiggle your toes…
see the difference? This is
because you have more motor cortex devoted to your fingers
than you do in your toes!
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Frontal Lobe Continued…
Includes the Prefrontal Cortex
‐
Critical for planning
movements and for certain aspects of memory, problem solving, emotion, complex
thought
Let’s test this…you’ll need a watch or
timer
Read the following words on the next slide out loud- how fast can
you do it?
Ready? GO!
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Stroop Test
Red Yellow Green Green Yellow Yellow
Blue Blue Red
Red Red Green
Blue Green Blue
Green Blue Blue
Pretty Easy, Right?
Now, read the word-
NOT the color
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Stroop Test
Red Yellow Green
Green Yellow Yellow
Blue Blue Red
Red Red Green
Blue Green Blue
Green Blue Blue
A little bit harder, right?
Now, read the COLOR not the
Word
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Stroop Test
Red Yellow Green
Green Yellow Yellow
Blue Blue Red
Red Red Green
Blue Green Blue
Green Blue Blue
SO, why did it get harder at the end?
Most people will take longer to do the color
version than the black/white version. This is due to concentration… much harder to say the color of the word and not the word.
Word processing is much faster than color
processing. The conflicting word information
arrives as the decision process stage earlier than the color information and results in confusion.
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