Transcript Chapter 2 - Neuroscience and Behavior

Your Amazing Brain
• Receives information – within a fraction of
a second, too minuscule to measure
• Acts on the external universe – allows you
to cry, walk, play a musical instrument
• Utilizes language – one of your most
advanced functions
• Possesses emotions – creates your affective
universe
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Your Amazing Brain
• Thinks –is responsible for your memory,
intelligence, your thoughts
• Controls your autonomic functions – heart
rate, breathing, homeostasis
• Controls your immune system – protects
you from viruses
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Peripheral Nervous System
• Handles the CNS’s input and output.
• Contains all the portions of the NS outside
of the brain and spinal cord.
• Contains sensory nerves and motor nerves
• Divided into autonomic nervous system
and somatic nervous system.
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Peripheral Nervous System
• Sensory Nerves
(to the brain)
Carry messages from
special reporters in the
skin, muscles, and
other internal and
external sense organs
to the spinal cord and
then to the brain
• Motor Nerves
(from the brain)
Carry orders from CNS
to muscles, glands to
contract and produce
chemical messengers
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Peripheral Nervous System
• Somatic NS
Consists of nerves
connected to sensory
receptors and skeletal
muscles
Permits voluntary action
(writing your name)
• Autonomic NS
Permits the involuntary
functioning of blood
vessels, glands, and
internal organs such as
the bladder, stomach
and heart
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Autonomic Nervous System
• Sympathetic NS
Like the accelerator of
your car
Mobilizes the body for
action
Increases heart rate
Elevates blood pressure
• Parasympathetic NS
Like the brakes in your
car
Slows the body down to
keep its rhythm
Enables the body to
conserve and store
energy
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Sympathetic NS
and Emotion
• You perceive the sensory stimulus.
• The adrenal gland sends two hormones:
epinephrine and norepinephrine.
• They activate the sympathetic nervous system.
• That produces a state of arousal or alertness that
provides the body with the energy to act (the
pupils dilate, the heart beats faster, and breathing
speeds up).
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The Nervous System
The Central Nervous System
The Brain
The Spinal
Cord
The peripheral Nervous
System
The Somatic
Nervous
System
The
Autonomic
Nervous
System
The
parasympathetic
Nervous System
The
Sympathetic
Nervous
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System
Central Nervous System
• The Spinal Cord
• The Brain
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The Spinal Cord
• Protected by a column of bones
• Produces some behaviors of its own without
the help of the brain
• These spinal reflexes are automatic,
requesting no conscious effort
• Sometimes they are influenced by thought
and emotion
• Example: touching a hot iron
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The Brain
• Areas of the Brain
• The Four Lobes of the Brain
• Lateralization
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The Hindbrain
• Medulla – breathing, heart rate
• Pons – sleeping, walking, dreaming
• Riticular Activating System – alertness,
attention
• Cerebellum – balance, coordination for the
muscles
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The Forebrain
• Thalamus
Direct sensory messages to higher centers in
the brain
The sight of sunset is directed to a visual area
The only sense that completely bypasses the
thalamus is the sense of smell, which has its
private switching station, the olfactory
bulb
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The Forebrain
The Limbic System
The Amygdala
Responsible for evaluating sensory information
It determines its emotional importance
It makes the decision to approach or to withdraw
Its initial response may be overridden by the appraisal of the
cerebral cortex
The Hippocampus
The gate way to memory
The Hypothalamus
It is involved with drives associated with survival such as
hunger, thirst, emotion, sex, and reproduction
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The Forebrain
The Limbic System
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The
Endocrine
System
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The Endocrine System
• The body’s slow chemical communication
system; a set of glands that secrete
hormones into the blood stream.
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The Endocrine System
A Set of Glands
Thyroid gland – affects metabolism
Pancreas – regulates the level of sugar in the
blood
Parathyroids – help regulate the level of
calcium in the blood
Ovary – secretes sex female hormones
(estrogen)
Testes – secrete sex male hormone
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(Androgens)
The Endocrine System
A Set of Glands
The Adrenal Glands
A pair of endocrine glands just above the
kidney
They secrete epinephrine and norepinephrine
which help to arouse the body in times of
stress.
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The Endocrine System
A Set of Glands
The Pineal Gland
Helps secrete melatonin which helps to
regulate daily biological rhythms and
promotes sleep.
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The Endocrine System
A Set of Glands
The Pituitary Gland
A sort of master gland
It is cherry-sized endocrine gland
The hormones it secretes affect growth and the
secretion of other endocrine glands
The real boss is the hypothalamus
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Feedback System
Brain
Hypothalamus
Pituitary
gland
Hormones
Other
Glands
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The Forebrain
• The Cerebrum
Higher forms of thinking take place in it
It is divided into two halves called the
cerebral hemispheres that are connected
by a large band of fibers called the corpus
callosum
They have different tasks (lateralization)
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The Forebrain
• The Cerebral Cortex
The cerebrum is covered by several thin
layers of densely packed cells known as the
cerebral cortex
On each cerebral hemisphere, deep fissures
divide the cortex into 4 lobes
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The Four Lobes of the
Cerebral Cortex
Occipital
Lobes
-at the back
of the head
-Visual
cortex
Parietal
Lobe
-at the top
of the brain
-Somatosensory
cortex
-pressure,
touch, pain
Temporal
Lobes
-at the sides
of the brain
-Auditory
cortex
-memory,
perception,
emotion,
language
Frontal
Lobes
-toward the
front of the
brain
-Motor
cortex
-voluntary
movement
of muscles 29
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Functions of the Cortex
Motor Cortex – an area of the frontal lobes
that controls voluntary movements.
It sends messages out to the body.
When stimulating, specific parts of the
region in the left or right hemisphere,
specific body parts moved on the opposite
side of the body.
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Functions of the Cortex
Sensory Cortex – the area at the front of the parietal
lobes that receives, registers, and processes body
sensations.
Association Functions – areas of the cerebral cortex
that are not involved in primary motor or sensory
functions; rather, they are involved in higher
mental functions such as learning, remembering,
thinking, and speaking.
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Functions of the Cortex
Language
1- Broca’s Area – an area of the frontal
lobe, usually in the left hemisphere, that
directs the muscle movements involved in
speech
2- Wernicke’s Area – a brain area involved
in language comprehension and expression;
usually in the left temporal lobe.
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Specialization and Integration in
Language
1- Visual cortex – receives written words as visual
stimulation.
2- Angular gyrus – transforms visual representations
into an auditory code.
3- Wernicke’s area – interprets auditory code.
4- Broca’s area – controls speech muscles via the
motor cortex.
5- Motor cortex – word is pronounced.
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Lateralization
Left Hemisphere
Verbal competence
Speaking, reading,
thinking & reasoning
Processes info in
sequence
One piece of data at a
time
logical
Right Hemisphere
Nonverbal areas
Comprehension, spatial
relationships,
drawing, music,
emotion
Processes info. As a
whole
intuitive
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Emotion and Lateralization
Left Hemisphere
• Important for the
expression of positive
emotion
• Damage to the L.H.
leads to loss of the
capacity of joy.
• Activation in the L.H.
leads to tendencies to
approach other people.
Right Hemisphere
• Important for the
expression of negative
emotion
• Damage to the R.H. may
make people euphoric.
• Activation in the R.H.
leads to tendencies to
withdraw from people.
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Neurons
• The NS is made up in part of neurons
• They are held in place by glial cells
• The Function of Glial Cells:
– Provide neurons with nutrients
– Insulate neurons
– Remove cellular debris when neurons die
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The Structure of the Neuron
• 1- Dendrites
Act like antennas receiving messages
• 2- The Cell Body
Contains the biochemical machinery to keep
the neuron alive
• 3- The Axon
Transmits messages away from the cell body
to other neurons
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How Neurons Communicate
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Myelin Sheath
• Surrounds the axons
• A layer of fatty material, which is derived
from glial cells
• There are 2 purposes of the myelin sheath:
– To prevent signals from adjacent cells from
interfering with each other
– To speed up the production of neural impulses
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Stop!
• Is the brain
capable of
reorganizing
itself if
damaged?
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Plasticity
• When one brain area is damaged, other areas may
in time reorganize and take over some of its
functions.
• If neurons are destroyed, nearby neurons may
partly compensate for the damage by making new
connections that replace the lost ones.
• Examples: How the sense of touch in blind men
invades the visual part of the brain.
How the brain struggles to recover from a minor
stroke.
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Stop!
• Could damaged
neurons in the
central nervous
system multiply
and grow back?
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Precursor Cells
(Immature Cells)
• Precursor cells can give birth to new
neurons when immersed in a growthpromotion protein
• Physical and mental exercise promote the
survival and the production of new
precursor cells
• Stress can prohibit the production of new
cells
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• Nicotine can kill precursor cells
Chemical Messengers in the NS
• Neurotransmitters
• Endorphins
• Hormones
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Neurotransmitters
• Neurotransmitters travel from one neuron to
another. Changes occur in the receiving
neuron’s membrane,
• The ultimate effect is either:
– Excitatory: the probability that the receiving
neuron will fire increases
– Inhibitory: the probability that the receiving
neuron will fire decreases
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Neurotransmitters
Serotonin
Sleep, appetite, sensory perception, temperature
regulation, pain suppression, and mood
Dopamine
Voluntary movement, learning, memory, and
emotion
Acetylcholine
Muscle action, cognitive functioning, memory, and
emotion
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Neurotransmitters
Norepinephrine
Increased heart rate and the slowing of intestinal
activity during stress, learning, memory,
dreaming, waking from sleep, and emotion
GABA
(gama-aminobutyic acid)
The major inhibitory neurotransmitter in the
brain
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Why Not Flood the Brain with
Artificial Opiates?
• The brain may stop producing its own
natural opiates.
• For a drug addict, the result is agony until
the brain resumes production of its natural
opiates or receives more artificial opiates.
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Is Designing a Drug Easy?
• Dopamine as a drug doesn’t help because
dopamine doesn’t cross the blood-brain
barrier by which the brain fences out
unwanted chemicals circulating in the
blood.
• L-dopa, a raw material the brain can convert
to dopamine, can sneak through the fence.
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How Drugs and Other Chemicals
Alter Neurotransmitters
The agonist molecule
excites. It mimics the
effects of a
neurotransmitter on the
receiving neuron.
Morphine mimics the action
of neurotransmitters by
stimulating receptors in
the brain involved in
mood and pain sensation.
The antagonist molecule
inhibits by blocking the
neurotransmitters or by
diminishing their release.
Botulin poison causes
paralysis by blocking
receptors for acetylcholine
(a neurotransmitter that
produces muscle
movement)
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Endorphins
They have an effect similar to that of opiates.
They reduce pain and promote pleasure.
They play a role in appetite, sexual activity,
blood pressure, mood, learning, and
memory.
Some endorphins function as
neurotransmitters.
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Endorphins
Neuromodulators
Most endorphins act as neuromodulators,
which alter the effect of neurotransmitters
by limiting or prolonging their effects.
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Hormones
Insulin
Produced by the pancreas
Regulates the body’s use of glucose & affects
appetite
Melatonin
Secreted by the pineal gland
Helps to regulate daily biological rhythms and
promotes sleep.
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Hormones
Adrenal Hormones
Produced by the adrenal glands are involved in
emotion and stress. They rise in response to
nonemotional conditions, such as cold, heat, pin
injury, and physical exercise, and in response to
some drugs such as caffeine and nicotine.
The Outer Part
Cortisol
The Inner Part
Epinephrine (adrenalin) & Norepinephrine
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Hormones
Sex Hormones
Are secreted by the gonads and by the adrenal
glands
Androgens
Masculinizing Hormones
Estrogens
Feminizing Hormones
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Neurotransmitters & Hormones
Acetylcholine
Shortage in acetylcholine may be associated with
Alzheimer’s disease
Dopamine
The degeneration of brain cells that produce and use
another neurotransmitter, dopamine, appears to
cause symptoms of Parkinson’s disease.
Low levels of dopamine may cause ADHD
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Neurotransmitters & Hormones
Serotonin
Decrease in norepinephrine and serotonin is
associated with depression. Elevated levels along
with other biochemical and brain abnormalities
have been implicated in childhood autism.
Norepinephrine
Norepinephrine, epinephrine, and adrenaline are
associated with excitement and stress.
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Neurotransmitters & Hormones
Cortisol
Cortisol is associated with stress. Increase in cortisol
damages the brain and may be associated with
posttraumatic stress.
GABA
Abnormal GABA levels have between implicated in sleep
and eating disorders and in compulsive disorders.
Glutamate
Glutamate, serotonin, and high levels of dopamine have been
associated with schizophrenia
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