Neuroscience
Chapter 2
Parts of the Brain
A. The Lobes – divide the brain into 4 major sections by
fissures
1.
Frontal Lobe – area of the brain associated with higher
mental abilities, movement, personality and the sense of
smell
 Contains the Motor Strip – portion of the brain that
controls body movement – can be stimulated through electrical
impulse
 Importance to the body denotes designation of space in the MS
 Frontal Association Area
 Interprets & evaluates your environment – what is going on,
what to feel, makes sense of things going on around you
 Size reflects intelligence
 Damage to this portion can create serious problems with a
persons personality (inappropriate emotions, socially
unacceptable behavior, fewer inhibitions, failure to make longterm plans, easily distracted, difficulty understanding a string of
facts or events)
The Lobes Cont.
1. Parietal Lobe – Portion of the brain where
body sensations register (touch, temperature,
pressure etc)
 Contains the Sensory Strip – provides and
registers sensation
2. Occipital Lobes – responsible for processing and
interpreting visual information
 When damaged it effects what and how well a person
can see
3. Temporal Lobe – contains centers for hearing
and some language functions
The Hemispheres
• Hemispheres – The sides of the brain divided by a
large lengthwise fissure, both hemispheres work
together on most tasks
• Corpus Callosum – connects and allows for
communication between the right and left hemisphere
▫ When this is cut most communication between the 2
halves is cut off
• Dominance – this is the side of the brain that is
preferred over the other
▫ The hemisphere that is dominant controls most
actions and fine motor skills
▫ If you are left handed you are right brain dominant etc
Hemispheres cont.
• Left Hemisphere Tasks – local view
▫ Handles verbal and speech material, like encoding and syntax
some logic and writing, superior at judging time, math, rhythm &
coordinating complex movements like those associated with
speech
▫ Mainly involved in analysis and processing information
sequentially
• Right Hemisphere Tasks – global view
▫ Can produce only basic speech and numbers
▫ Deals with objects in space, recognizing patterns, faces, and
melodies, putting together a puzzle and drawing a picture, some
mathematical reasoning
▫ Helps express emotions and detect emotions of others
▫ Chances are these people will be better at nonverbal activities,
specializes in imagery
▫ Processes material simultaneously and holistically
The Cerebrum and the Cerebral Cortex
1. The outermost layer of the brain – the gray matter
2. Includes hemispheres, lobes and the frontal
association area
3. Controls very high-level thought and takes up
2/3rds of the brains nerve cells (100 billion)
4. Responsible for voluntary movements, sensations,
learning, remembering, consciousness etc.
5. Corticalization – the increase in the size and
wrinkles of the brain
▫ small correlation between brain size and
intelligence (not between humans & humans but
humans and other animals)
The Lower Brain
1.
2.
3.
▫
▫
The Lower Brain - communicates back and forth with the
cerebral cortex for non-automatic human responses
The Thalamus – acts as a sensory relay station sending
and receiving information to other parts of the brain
(vision, hearing, taste & touch) damage can cause
blindness, deafness, etc (not smell)
The Cerebellum – primarily regulates posture, muscle
tone & muscular coordination
Stores memories related to skills and habits (class
schedules, driving directions)
Damage – walking, running, playing catch are impossible,
area of the brain where degenerative diseases effect
coordinated motor function
The Lower Brain Cont.
4. The Hypothalamus – control center for emotions
and basic motives - helps control rage, pleasure,
hunger and sexual desire, temperature control
5. Reticular Activating System – works to catch
nerve impulses from the brain to the body and back
▫ Affects your alertness, sorts & prioritizes nerve
impulses, controls reflexes involved in breathing,
sneezing, coughing, and vomiting, and affects muscle
tone, posture, and movement of the head, eyes, face &
body
▫ Bombards the cortex with stimulation keeping it active
and alert
Brain Communication
A. Neuron – the nerve cell of the brain
1. Dendrite – short fibers that act as
receptors, receiving messages from
other nerve cells
2. Axon – Long single extension of a
neuron, covered with myelin sheath
to insulate and speed up messages
through neurons.
B. Synapse – space between the axon
of one neuron and the dendrite of
another neuron
1. Vesicle – bubble like containers
that hold chemical molecules called
neurotransmitters
Communication Demo
http://youtu.be/FR4S1BqdFG4
Action Potential
A neural impulse. A brief
electrical charge that travels
down an axon and is
generated by the movement
of positively charged atoms
in and out of channels in the
axon’s membrane.
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Depolarization & Hyperpolarization
Depolarization: Depolarization occurs when
positive ions enter the neuron, making it more
prone to firing an action potential.
Hyperpolarization occurs when negative ions
enter the neuron, making it less prone to firing
an action potential.
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Threshold
Threshold: Each neuron receives depolarizing
and hyperpolarizing currents from many
neurons. When the depolarizing current
(positive ions) minus the hyperpolarizing
current (negative ions) exceed minimum
intensity (threshold) the neuron fires an action
potential.
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Action Potential Properties
All-or-None Response: When the depolarizing
current exceeds the threshold, a neuron will
fire. If the depolarizing current fails to exceed
the threshold, a neuron will not fire.
Intensity of an action potential remains the
same throughout the length of the axon.
Synapse
Synapse [SIN-aps] a junction between the axon
tip of the sending neuron and the dendrite or
cell body of the receiving neuron. This tiny gap
is called the synaptic gap or cleft.
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Neurotransmitters
Neurotransmitters
(chemicals) released
from the sending
neuron travel across the
synapse and bind to
receptor sites on the
receiving neuron,
thereby influencing it to
generate an action
potential.
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Reuptake
Neurotransmitters in
the synapse are
reabsorbed into the
sending neurons
through the process of
reuptake. This process
applies the brakes on
neurotransmitter
action.
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Lock & Key Mechanism
Neurotransmitters bind to the receptors of the
receiving neuron in a key-lock mechanism.
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Agonists
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Antagonists
Neurotransmitters
The Spinal Cord
1. The neurons in the spinal cord are short, direct
and powerful.
2. Has fewer synapses – shorter time for
information to be received and an action to
occur
3. Reflex – activation of the muscle(s) before the
message is received by the brain (dropping a
baby)
The Endocrine System
• The Pituitary Gland – small bean shaped gland attached to
and controlled by the hypothalamus
▫ Responsible for sending messages to other glands to activate
them
▫ Responsible for determining the height of the person
▫ The gland creates a growth hormone which appears in the
body’s system sporadically resulting in on and off growth
spurts
▫ Can be effected by the environment and diet of the
individual
• Thyroid Gland – located in the neck this gland controls a
persons metabolism
▫ This affects the rate a which a person’s body operate, inactive
thyroid = a sluggish person, a overactive thyroid = jumpy and
hyper person
The Endocrine System cont.
• The Adrenal Gland – located on the right and left
side of the body above the kidneys
▫ Responsible for putting adrenaline in to the
bloodstream
 Affects us by increasing breathing, blood pressure,
muscles tension & energy level
▫ Will also release a chemical that allows for the
faster clotting of blood
▫ This happens during testing or any other high
anxiety time (fight or flight reaction)
 TIP: to decrease test anxiety force yourself to take slow
deep breaths, this will stimulate brain activity instead of
shutting it down to prepare for an emergency
The Endocrine System cont.
• The Gonads – sex glands located in the testis in males
and the ovaries in females
▫ Androgen – the male hormone that stimulates the
growth of hair, the deepening of the voice and the
production of sperm
 Starts the sex drive of both males and females
 Sex drive is taken over by the cortex which allows us to
associate other emotions like love and caring with the act of
intercourse
▫ Estrogen – the female hormone that causes the
production of eggs the enlargement of the mammary
glands and the menstrual cycle to begin
 Both of these hormones are produced in the gonads and
released during the middle teenage years
The Nervous System
• The nervous system is our body’s electrochemical information network (interstate
highway)
▫ Central Nervous system – includes our brain
and spinal cord
▫ Peripheral Nervous system – links the CNS
with the body’s sense receptors, muscles and
glands. (Broken down further)
Types of Neurons
• Axons – are grouped & bundled as cables that
shoot messages back and forth along our nerves
▫ Sensory neurons - gather and send info to the
CNS
▫ Motor Neurons – sends messages from the CNS
to the body’s tissues and muscles
▫ Inter Neurons – communicate between the
sensory neurons and motor neurons
Peripheral Nervous System
• Somatic Nervous System – controls
voluntary skeletal muscles
• Autonomatic Nervous System – controls
involuntary glands and muscles, like those
associated with our internal organs
▫ Sympathetic – arouses, alarms, enrages or
challenges you (Fight or Flight) accelerates your blood
pressure, heart rate, slows digestion, raises blood
sugar, creates persperation
▫ Parasympathetic – conserves or calms the body,
(Rest & Digest) decreases HR, BP, BS, etc
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The Brain’s Plasticity
The brain is sculpted by our genes but also by our
experiences.
Plasticity refers to the brain’s ability to modify
itself after some type of injury or illness.
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Our Divided Brain
Our brain is divided into two hemispheres.
The left hemisphere processes reading, writing,
speaking, mathematics, and comprehension
skills. In the 1960s, it was termed as the
dominant brain.
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Splitting the Brain
A procedure in which the two hemispheres of the
brain are isolated by cutting the connecting fibers
(mainly those of the corpus callosum) between them.
Martin M. Rother
Courtesy of Terence Williams, University of Iowa
Corpus Callosum
Split Brain Patients
With the corpus callosum severed, objects (apple)
presented in the right visual field can be named.
Objects (pencil) in the left visual field cannot.
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Divided Consciousness
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Try This!
Try drawing one shape with your left hand and
one with your right hand, simultaneously.
BBC
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Non-Split Brains
People with intact brains also show left-right
hemispheric differences in mental abilities.
A number of brain scan studies show normal
individuals engage their right brain when
completing a perceptual task and their left brain
when carrying out a linguistic task.
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Now Try This!
1. Rotate your dominate hand in 1 direction and at
the same time rotate the opposite foot in the other
direction.
a. How difficult was that task? (scale of 1-5)
2. Next rotate your dominate hand in 1 direction
while rotating the foot on the same side of your
body in the other direction.
a. How difficult was that task? (scale of 1-5)
3. Tap you right index finger rapidly while turning to
a partner to recite the alphabet backwards.
Hemispheric Processing
D
D
D
D
D
D
D
D
DDDDDD
D
D
D
D
D
D
D
D
• When people are asked to
name the large
compositive letter, the H,
there is more activity in
the right hemisphere
(holistic perception).
• On the other hand, when
asked to name the small
component letters, there is
more activity in the left
hemisphere.
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Which Face is Happier?
• Most people choose the face on the left.
• Information from the left side of the picture goes to the
right hemisphere which is dominant for interpreting
emotional expressions.
Brain Organization & Handedness
Is handedness inherited? Yes. Archival and
historic studies, as well as modern medical
studies, show that the right hand is preferred.
This suggests genes and/or prenatal factors
influence handedness.
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Is it Alright to be Left Handed?
The percentage of left-handed individuals
decreases sharply in samples of older people
(Coren, 1993).
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