Transcript CH. 2 (BIOLOGY)

CHAPTER 2
NEUROSCIENCE
AND BEHAVIOR
Phrenology
A theory of personality
formulated in the 18th and 19
centuries by German physician
Franz Joesf Gall. It stated that
specific abilities or personality
traits are represented by specific
areas of the brain. The size of
these brain areas determines the
degrees of the corresponding skill
or trait. Although wrong in most
respects, the theory suggested the
idea of localization of function.
Biological Psychology

Biological Psychology
(a.k.a. biopsychology/psychobiology):
The study of psychological processes
from a biological point of view
NEURONS

Nerve cells that run throughout our body.
They send and receive messages from other
structures in the body such as muscles and
glands. Neurons receive, integrate and
transmit information in the form of signals.

There are 3 main types of neurons: sensory
neurons, interneurons, and motor neurons
A “TYPICAL” NEURON
Neuron: an individual nerve cell. Neurons are the basic building blocks of the
nervous system. They receive, integrate and transmit information in the form
of signals. It is estimated that humans have 100-180 billion.
Components of a Neuron
Soma (Cell Body): Contains the nucleus (a body within
the soma that contains the cell’s hereditary material of the cell)
it produces energy that fuels the activity of the cell
Components of a Neuron
Dendrites: The short, branched projections of a neuron
that receive impulses from axons terminal on other neurons
and conduct them toward the cell body.
Components of a Neuron
Axon:
The long projection that transmit impulses away
from the cell body to the synapse.
Components of a Neuron
Myelin Sheath:
A white fatty substance that insulates
and protects the axon. The myelin helps speed the impulses.
The loss of muscle control seen with multiple sclerosis is due
to a degeneration of myelin sheath.
Components of a Neuron
Nodes of Ranvier: the regularly spaced gaps in the myelin
sheath. The gaps permit the nerve impulses to leap from one node
to the next thus speeding the transmission of the message
Components of a Neuron
Axon Terminals (Terminal Buttons): The endings on axons.
They are small knobs that secrete chemicals called
neurotransmitters.
Neural Communication

Action Potential: A brief electrical charge
that travels down the axon of a neuron. It
works its way from the dendrites to the axon
terminal, much as a bite of swallowed food
makes its way from your mouth to your
stomach.
http://www.youtube.com/all_comments?v=U0NpTdge3aw
Neural Communication

Selectively Permeable: allows some
particles to pass in and out while blocking
other.
The selectively permeable surface of the axons
allows positive ions in

Ions: molecules that carry positive or negative
electrochemical charge

Stimulus Threshold: The minimum level of stimulation
required to activate a particular neuron
http://www.youtube.com/watch?v=ifD1YG07fB8
Neural Communication

All-or-None-Law/Principle: The
principle stating that either a neuron is
sufficiently stimulated, and an action potential
occurs or a neuron is not sufficiently
stimulated and an action potential does not
occur. A neuron always fires at the same
intensity; all action potentials have the same
strength
Neural Communication

Refractory Period: A short period between
action potentials; it is so short that a neuron
can send action potentials down its axons at
rates of up to 1000 per second.
How Neurons Communicate

Synapse: The tiny gap between the axon
terminal of the sending neuron and the
dendrites of the receiving neuron

It is across this tiny gap
that neurons communicate
with one another
Neurotransmitters

Neurotransmitters are chemical messengers
released from the axon terminals.

Neurotransmitters will bind only to specific
receptors on the postsynaptic membrane
that recognize them.
How Neurotransmitters Influence Us

Acetylcholine (ACh): A neurotransmitter
that causes excitation at synapses between
motor neurons and skeletal muscles, causing
the muscle to contract. It also plays a crucial
role in learning and memory. Insufficient
supply of Ach is related to Alzheimer’s
disease.
How Neurotransmitters Influence Us

Endorphins:
found mainly in the pituitary gland they are
the natural opiates released in response to
pain and vigorous exercise. The release of
endorphins during vigorous exercise
explains a “runner’s high” and their release
in response to pain explains why some
injured people are indifferent to pain.
Table 2.1
Myers: Psychology, Eighth Edition
Copyright © 2007 by Worth Publishers
How Drugs & Other Chemicals
Alter Neurotransmission

What happens when the brain is
flooded with drugs such as heroin and
morphine?
The brain may stop producing its own
natural opiates, and withdrawal of these
drugs may result in discomfort until the
brain resumes production of its natural
opiates
How Drugs & Other Chemicals
Alter Neurotransmission

Agonists:
A drug that boosts the effect of a
neurotransmitter. For example, Prozac
reduces depression by enhancing the
availability of serotonin at the synapse.
Prozac, therefore, is a serotonin agonist.
How Drugs & Other Chemicals
Alter Neurotransmission

Antagonists:
A drug that blocks the effects of a neurotransmitter. For
example, ACh triggers muscle contraction. Some native
tribes in S. America use a poison called curare, to coat the
tips of the darts they use in their blowguns. When these
darts strike an animal, the result is paralysis, because the
curare molecules fill the receptor sites on dendrites that
normally receive ACh, but the curare molecules do not
stimulate an action potential in the receiving neuron the way
ACh would. This means the ACh is blocked from doing its
job and movement ceases. Therefore curare is an
antagonist.
The Nervous System


A complex combination of cells that
allows you to gain information about
what is going on inside and outside your
body and to respond appropriately
It is comprised of the Central Nervous
System and the Peripheral Nervous
System
The Nervous System
http://www.youtube.com/watch?v=4Gdjcd68sGE
Peripheral Nervous System

Nerve cells that send messages
between the CNS and all the parts
of the body, such as muscles,
organs, and skin receptors.
Peripheral Nervous System
Somatic
Nervous System
Autonomic
Nervous System
Controls voluntary
activities
Controls involuntary
actions. It regulates the
body’s vital functions:
breathing, digestion, blood
pressure, etc. It is also
involved in emotions
It serves arousal
functions
Peripheral Nervous System
AUTONOMIC NERVOUS SYTEM
Parasympathetic
Nervous System
Sympathetic
Nervous System
Calms the body after
emergencies. Restores
the body’s energy
Prepares the body for
fight-or flight
response
The Peripheral Nervous System
Three Types of Neurons

Sensory Neurons
Carry information from the sense receptors to the spinal
cord and brain.

Motor Neurons
Nerves that carry information away from the brain and
spinal cord to the muscles and glands so they can takes
action

Interneurons
Nerve cells in the brain & spinal cord that are responsible
for processing information, they are neither sensory nor
motor but connect other neurons within the CNS
Central Nervous System

Brain and the Spinal Cord
Central Nervous System

Reflexes: (1st proposed by R. Descartes)
Automatic responses to stimuli. A simple
spinal reflex pathway is composed of a single
sensory neuron and a single motor neuron.
They often communicate
through an interneuron.
Which Nervous System?

Which nervous system is involved in
allowing you to shoot a basketball, smell
freshly baked bread, and push the keys on
a piano?
Somatic Nervous System
Which Nervous System?

The digestion of last night’s dinner is
most directly controlled by which
nervous system?
Autonomic
Which Nervous System?

The voluntary command Zelda uses to
raise her hand in class would travel
through which nervous system from the
spinal cord to the muscles that control
movement?
Somatic
Which Nervous System?

When a man grabbed Zoe’s purse, she ran
after him, tackled him, and retrieved her
purse. Then she realized that her heart
was racing, her breathing was irregular,
and she was trembling.
Which of Zoe’s nervous systems was
responsible for this reaction?
Sympathetic
Which Nervous System?



You woke up late for your big job
interview! You are running and your heart
is beating fast!
Which nervous system governs your
running?
Somatic
Which nervous sytem governs your heart
rate?
Autonomic
Which Nervous System?

Zeon had a long, difficult day at school. As
he sits down on the sofa, his heart rate and
breathing slow down, his muscles relax, and
his digestive system starts getting ready for
food. Which of Zeon’s nervous systems has
been activated?
Parasympathetic
The Endocrine System
The endocrine system contains hormones
which stimulate growth and many kinds
of reactions.
Hormones have specific receptor sites.
Hormones are produced by glands such as
the pituitary gland, the thyroid gland, the
adrenal gland, the testes, and the ovaries.
Hormones are to the endocrine
system as ______________ are
to the _________________
The endocrine system is
faster/slower than the nervous
system
Thyroid Gland:
Secretes
hormones
involved in
metabolism
Hypothyroidism (too
little thyroxin) leads to
being overweight
Hyperthyroidism (too
much thyroxin) leads to
weight loss, inability to
sleep, excitability, etc.
Adrenal Gland: The
outer layer of the
adrenal glands
secretes cortical
steroids which
increase resistance to
stress and promote
muscle development.
Cortical steroids also
release stored sugar,
making energy
available for
emergencies.
Pituitary
Gland: is also
known as the
“master gland”
because it
secretes many
hormones that
affect a wide
range of
behaviors such
as growth,
pregnancy,
mothering, etc.
Testosterone: A male
sex hormone produced by
the testes in the male.
If, in the prenatal period,
testosterone is secreted
male sex organs develop.
However, if testosterone
is NOT secreted, female
sex organs develop. In
adolescence, testosterone
aids in the growth of
muscle and bone and in
the development of
primary and secondary
sexual characteristics
Estrogen and
Progesterone:
female sex hormones
secreted by the
ovaries
Estrogen is involved
in the development
of primary and
secondary sexual
characteristics
The Brain

The Tools of Discovery
Lesion: a naturally or experimentally
caused destruction of brain tissue
 Clinical Observation: The oldest method
of studying the brain. People with brain
injuries or diseases and observe how these
injuries effect their functioning. These
clinical observations have helped scientists
map the brain. (Ex. Phineas Gage)

METHODS OF STUDYING THE
BRAIN

Electroencephalogram (EEG):
Records the electrical activity of the brain
creating “brain waves” It is frequently
used in studying sleep, monitoring the
depth of anesthesia, diagnosing epilepsy,
and other brain disorders or dysfunction,
as well as studying normal brain function
METHODS OF STUDYING THE
BRAIN
Neuroimaging Techniques
 PET Scans:

The test involves injecting a very small dose of a
radioactive glucose into the vein of your arm. The glucose
travels through the body and is absorbed by the organs and
tissues being studied. Next, you will be asked to lie down
on a flat examination table that is moved into the center of
a PET scanner—a doughnut-like shaped machine. This
machine detects and records the energy given off by the
tracer substance and, with the aid of a computer, this
energy is converted into three-dimensional pictures. A
physician can then look at cross-sectional images of the
body organ from any angle in order to detect any functional
problems.
PET SCAN Image
METHODS OF STUDYING THE
BRAIN

Types of Scans

CAT Scans: Produce a 3dimensional view of the brain that
can be displayed on a video
monitor
This is what the image looks like
taken by a CAT scan
This is NOT the type of CAT Scan to
which I am referring
METHODS OF STUDYING THE
BRAIN

Types of Scans

MRI: more powerful than a CAT Scan
and can show detail more clearly
METHODS OF STUDYING THE
BRAIN

Functional Magnetic Resonance Imaging
(fMRI)
This technique can reveal the brain’s
functioning as well as its structure. Blood
goes where the brain is especially active.
Therefore researchers can watch the brain
light up as a person performs different
mental functions.
ORGANIZATION OF THE BRAIN
Older Brain Structures

The Brainstem: the oldest part and
central core of the brain. It begins where
the spinal cord swells as it enters the skull.
It is responsible for automatic
survival functions.
It is comprised of…
 Medulla
 Pons
http://www.youtube.com/watch?v=snO68aJTOpM
Older Brain Structures

Brainstem
Medulla: located at the base of the
brainstem, it controls basic life support
functions like heartbeat and breathing
 Pons: it works with the cerebellum in
controlling equilibrium, and with the
cerebral cortex in
smoothing and
coordinating voluntary
movements.

Older Brain Structures

Reticular Formation (Reticular Activating
System: RAS): It is involved in arousal,
alertness, and sleep-wake cycles. Alcohol
can disrupt the activity of the RAS thus
affecting alertness and reaction time. If the
fibers from the RAS are disconnected from
the brain, a person goes into a permanent
coma
Older Brain Structures

Thalamus: The brain’s sensory switchboard,
located on top of the brainstem; it directs
messages for all senses EXCEPT smell

Cerebellum: (Latin for Little Brain): Helps
coordinate voluntary movement and balance
cerebellum
The Limbic System

Limbic System: Contains
Amygdala
 Hypothalamus
 Hippocampus

(HAH!=Hippocampus, Amygdala, Hypothalamus)
The Limbic System

Amygdala: An almond shaped neural
cluster in the limbic system that controls
emotional responses, such as fear, aggression
and anger.
The Limbic System

Hypothalamus: It helps regulate many of
the body’s maintenance activities, such as
eating, drinking, body temperature, sex drive,
etc. It is also linked to emotions such as
pleasure

Reward centers are located in the hypothalamus.
When allowed to trigger their own stimulation in
these reward centers by pressing a pedal, rats
would sometimes do so at a feverish pace until
they dropped from exhaustion.
The Limbic System

Hypothalamus
Lateral Hypothalamus:
Tells us we are hungry
 Ventromedial Hypothalamus
Tells us we are full

The Limbic System

Hippocampus: (Hippo is Greek for horse).
The hippocampus is a horse shoe shaped
structure that helps process new memories for
permanent storage.
The Cerebral Cortex

Cerebral Cortex:

The brain’s wrinkled outer surface that
make up the body’s ultimate control and
information processing center. It is the
largest and most complex part of the
human brain, making up 2/3 of the weight
of the entire nervous system. It is
responsible for out most complex
activities such as learning, remembering
& thinking.
Memory Cues for Parts of the Brain
Term
Keyword Meaning
Broca’s
Area
Broken
Directs muscles
for speech
production
Imagine breaking a talking doll.
If it gets broken (Broca), it won’t
talk (speech) anymore
Parietal
Lobe
Parent
Sense of
touch
Imagine that a parent (parietal) is
touching his/her baby’s forehead
to feel if the baby has a
temperature
Judgment
You & a friend have a dispute
over a box of cereal. So, you go
to cereal court (cerebral cortex)
and face a judge (judgment)
Cerebral Cereal
Cortex Court
Your Mental Picture
Memory Cues for Parts of the Brain
Term
Keyword Meaning
Your Mental Picture
HypoHypoHunger &
Thalamus chondriac Thirst
Imagine a hypochondriac
(hypothalamus) thinking they’re
hungry & thirsty when they’re not
Amygdala
Armageddon
Aggression
& Fear
In the Bible, Armageddon
(amygdala) is the final battle
between good and evil. Battles of
full of aggression
Frontal
Lobe
Front
Impulse
control
Imagine a student losing patience &
crowding to the front of the line.
He has lost impulse control.
Corpus
Corpse
Callosum
Connects the 2 Imagine a tiny corpse (corpus) lying
cerebral
across (connecting) the two cerebral
hemisperes
hemispheres
Memory Cues for Parts of the Brain
Term
Key word Meaning
Your mental picture
Left
Left Field Handles
Hemisphere
Language
Imagine a Ryan Braun in left
field talking (language)
continuously during a game (for
example, “swing, batter, swing
batter, etc)
Temporal
Lobe
Tempera
Paints
Hearing
Imagine someone painting
tempera paint (temporal) all over
their ears (hearing) “These ears
aren’t painted on,” she says
HippoCampus
Hippo
Memories
Imagine a hippo (hippocampus)
wearing an elephant trunk as a
Halloween costume. “It helps
my memory!” he says
Structure of the Cortex

Glia Cells:

Cells in the nervous system that
support, nourish, and protect neurons.
FOUR LOBES OF THE BRAIN
PARIETAL LOBE
FRONTAL LOBE
OCCIPITAL LOBE
TEMPORAL LOBE
Functions of the Cortex

Motor Functions

Motor Cortex: It initiates voluntary
movements in specific parts of the body
(right side of the brain controls the left side
of the body, etc.)
Functions of the Cortex

Mapping the Motor Cortex

Those areas of the body
requiring precise control
(such as the fingers and
the mouth) occupy the
greatest amount of
cortical space.
Functions of the Cortex

Neural Prosthetics

In an effort to find the source of motor control,
researchers have recorded messages from brain
areas involved in planning and intention,
leading to testing of neural prosthetics for
paralyzed patients. Paralyzed patients are now
able to mentally to mentally control a
television, play video games, etc.
http://www.usatoday.com/money/industries/health/story/2011-10-15/robotic-touch/50774398/1
Functions of the Cortex

Sensory Functions
 Sensory Cortex
 A region at the front of the parietal
lobes, it registers and processes body
sensations. The most sensitve body
parts (i.e your finger tips) require the
largest amount of space in the
sensory cortex

http://opl.apa.org/contributions/EC/Hom.htm
Functions of the Cortex

Association Areas

Association areas are found in all four lobes.
They are involved in higher mental
functions, such as learning, remembering,
thinking, and speaking
Language


Broca’s Area
Wernicke’s Area
Language

Aphasia: loss or impairment of the ability
to understand language or express oneself
through language due to brain injury or
disease
Language

Broca’s Area:
(discovered by Paul Broca in
the 1880s) directs the muscle movements involved
in the production of speech (expressive language)
Damage to Broca’s area (which often happens to
stroke victims) results in difficulty with spoken
languate. Stroke victims can form ideas but can’t
turn those ideas into coherent speech
Their comprehension of speech is fine
and their ability to sing familiar songs
are fine
Language

Wernicke’s Area: (discovered by Carl
Wernicke in 1874) it is involved with your
ability to understand what someone else
says (receptive language). Damage to
Wernicke’s area might leave a person able to
hear words but unable to comprehend the
meaning of sentences created with the
words.
Language

Describe the 5 brain areas that would be
involved if you read this sentence aloud.





1. registered in the visual area
2. relayed to the angular gyrus which transforms
the words into an auditory code
3. the auditory code is received & understood in
the nearby Wernicke’s area
4. it is then sent to Broca’s area
5. which controls the motor cortex as it creates the
pronounced word
The Brain’s Plasticity

Plasticity: the brain’s capacity for
modification, as evident in brain
reorganization following damage (especially in
children)
Our Divided Brain

Splitting the Brain: To control the disease of
epilepsy, it is sometimes necessary to cut the
corpus callosum so that seizures do not spread
form one hemisphere to another
 Corpus Callosum: the wide band of axon
fibers that connects the two brain hemispheres

Split brain: a split brain is one whose corpus
callosum has been severed
Studying Hemispheric Differences in
the Intact Brain

Laterization: the tendency for one cerebral
hemisphere to excel at a particular skill
compared with the other hemisphere
LANGUAGE ABILITIES

Left Hemisphere:
Language Functions are based in the left
hemisphere for most people
LEFT VS. RIGHT HEMISPHERE

Left: logic, problem solving,
mathematical computation, etc.


Right: imagination, art, feeling, and
spatial relations
However… People are NOT right or left
brained. The hemispheres do NOT act
independently of each other