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10/15/2010
Biology and Behavior
Behavioral neuroscience:
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Biology and Behavior
To survive, human beings must be able to perform three
interrelated activities: sensing events, or stimuli; processing
stimuli; and responding to stimuli.
Stimulus:
Receptors:
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The Nervous System
The activities of sensing, processing, and responding are
coordinated and controlled by the nervous system, which has
two major divisions: the central nervous system (CNS) and
the peripheral nervous system (PNS).
CNS:
PNS:
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Divisions of the Nervous System
Central Nervous System
Brain
Spinal cord
Peripheral Nervous System
Somatic
Autonomic
Sympathetic
Parasympathetic
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The Nervous System
Somatic nervous system:
afferent (sensory) nerves:
efferent (motor) nerves:
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The Nervous System
Autonomic nervous system:
sympathetic nervous system
parasympathetic nervous system.
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The Nervous System
The CNS
The spinal cord serves as the body’s “information
superhighway.”
We’ll talk about thr brain in a bit…
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The Nervous System
Reflexes:
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The Endocrine System
Endocrine system
hormones.
Pineal gland:
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The Endocrine System
Endocrine system:
Ductless glands that regulate
growth, reproduction,
metabolism, mood, and some
behavior
Hormones:
Chemical messengers
secreted into the bloodstream
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The Endocrine System
Pancreas:
Hypothalamus:
Pituitary gland:
Thyroid gland:
Gonads—ovaries in women and testes in men:
Adrenal glands:
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Neurons: Basic Cells of the Nervous
System
The cells that make up the nervous system are called
neurons.
Neurons are composed of:
dendrites that receive signals from adjacent
neurons,
a cell body or soma,
an axon that transmits signals, and
terminal buttons that contain
neurotransmitters.
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Structure of a Neuron
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Neurons: Basic Cells of the Nervous
System
One of the major differences among neurons is found in their
axons.
Some axons are surrounded by a myelin sheath, which is a
fatty protein substance.
Myelin:
Nodes of Ranvier:
Glial cells
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Neurons: Basic Cells of the Nervous
System
Because a neural signal is sent from one neuron to the
next through the terminal buttons of the axons, the most
common arrangement is for a neuron’s terminal buttons
to be near, but not touching, the receptive dendrites of
neighboring neurons.
The membrane on the side that sends the message is the
presynaptic membrane, while the membrane on the
receiving side of the synapse is the postsynaptic membrane.
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Neurons: Basic Cells of the Nervous
System
The most common arrangement at the end of an axon
consists of a terminal button to send the signal, a dendrite to
receive the signal, and the gap between the two, which is the
synapse.
Neurotransmitters:
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The Synapse
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Neurons: Basic Cells of the Nervous
System
When the electrical signal reaches the terminal buttons, it
causes the vesicles in the terminal button to release a
chemical signal in the form of a neurotransmitter into the
synapse.
As the neurotransmitter enters the synapse, it contacts the
postsynaptic membrane (usually the dendrite) of the next
neuron.
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Neurons: Basic Cells of the Nervous
System
The neuron that is receiving the neurotransmitter may
become more likely to transmit the message to subsequent
neurons; this process is called excitation.
In other instances, the neuron that receives the
neurotransmitter becomes less likely to transmit the message
to subsequent neurons; this process is called inhibition.
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Neurons: Basic Cells of the Nervous
System
Dopamine:
Serotonin:
Acetylcholine:
Glutamate:
GABA (gamma-aminobutyric acid):
Norepinephrine (which is also a hormone):
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Neurons: Basic Cells of the Nervous
System
Synapses must be cleared, and cleared rapidly, before additional
signals can be transmitted.
The synapse is cleared in one of two ways, depending on the
particular neurotransmitter involved.
Breakdown:
Reuptake:
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Neurons: Basic Cells of the Nervous
System
Most drugs exert their effects by influencing the
operation of a neurotransmitter: Some drugs increase
the effectiveness of neurotransmitters; other drugs
reduce their effectiveness.
agonists.
antagonists.
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Agonists
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Antagonists
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Neurons: Basic Cells of the Nervous
System
Neuromodulators:
Endorphins:
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Neurons: Basic Cells of the Nervous
System
The Neural Signal:
Neurons are electrically charged:
Resting state:
resting potential:
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Neurons: Basic Cells of the Nervous
System
When a neurotransmitter enters the synapse, it may result in
either:
depolarization (the neuron becomes less
negatively charged) or
hyperpolarization (the neuron becomes more
negatively charged).
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Neurons: Basic Cells of the Nervous
System
Action potential:
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The Brain: A Closer Look
In the 1800s, German physician and anatomist Franz
Joseph Gall developed the pseudoscience phrenology
(“science of the mind”).
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The Brain: A Closer Look
In 1861, the French physician Paul Broca used a technique for
understanding the brain—the clinical or case study method.
Broca’s area:
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The Brain: A Closer Look
Phineas Gage’s story is one of the most famous cases of
survival from massive brain injury.
Gage, a railroad foreman, was working with explosives in
Cavendish, Vermont, on September 13, 1848, trying to clear
a railroad right-of-way through granite bedrock.
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The Brain: A Closer Look
The stereotaxic instrument holds the head in a fixed position
and allows an electrode (a fine piece of specially-treated
wire) to be inserted into a specified area of a patient’s brain.
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The Brain: A Closer Look
In 1929, Hans Berger developed the
electroencephalograph (EEG):
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The Brain: A Closer Look
Brain waves (identified by Greek letters) are distinguished by
their frequency, which is measured in cycles per second (called
hertz and abbreviated Hz), and their amplitude (the height of the
wave on the EEG record), which reflects strength.
Brain researchers have labeled a number of different types of
brain waves; each is generally associated with a particular state of
consciousness.
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The Brain: A Closer Look
Alpha waves:
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The Brain: A Closer Look
Beta waves:
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The Brain: A Closer Look
Theta waves:
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The Brain: A Closer Look
Delta waves:
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The Brain: A Closer Look
The advent of computers has led to major advances in the
study of the brain.
Positron emission tomography (PET):
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The Brain: A Closer Look
Computerized axial tomography (CT or CAT):
Magnetic resonance imaging (MRI):
Functional magnetic resonance imaging (fMRI):
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The Brain
The brain is divided into
the hindbrain, the
midbrain, and the
forebrain.
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The Brain: A Closer Look
The major components of the hindbrain are the medulla, the
pons, and the cerebellum.
From an evolutionary perspective, these are the oldest parts of
the brain, and they have important survival functions.
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The Brain: A Closer Look
The medulla (short for medulla oblongata):
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The Brain: A Closer Look
The pons:
The cerebellum:
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The Brain: A Closer Look
Together, the hindbrain and midbrain are known as the
brain stem because they form the stem, or stalk, on which
the remainder of the brain rests.
The midbrain:
Psychologists have found that this complex network of
fibers, known as the reticular formation, is very
important in controlling our level of arousal or alertness.
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The Brain: A Closer Look
The forebrain:
These two halves or hemispheres are connected by a wide
band of fibers known as the corpus callosum (“hard
body”).
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The Brain: A Closer Look
The two hemispheres of the forebrain communicate with
each other through the corpus callosum.
The cerebral cortex (cerebrum):
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The Brain: A Closer Look
Deep down in the brain—below the cortex—is the basal
ganglia:
The limbic system:
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Major Components of the Limbic
System
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The Brain: A Closer Look
The thalamus:
Each cerebral hemisphere has four specific areas, called
lobes—the frontal, temporal, parietal, and occipital lobes.
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The Brain: A Closer Look
The frontal lobes:
The major responsibility of the parietal lobes:
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The Brain: A Closer Look
The temporal lobes :
The occipital lobes’:
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The Brain: A Closer Look
Neuroscientists have focused on the brain structures responsible
for language as well as the problems that develop when these
areas are damaged.
Broca’s area:
Wernicke’s area:
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The Brain: A Closer Look
The term aphasia refers to a loss of the ability to speak or
understand written or spoken language.
Damage to Broca’s area results in nonfluent aphasia.
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The Brain: A Closer Look
In 1874, the German neurologist Carl Wernicke (1848–1905)
identified a second brain area that plays a significant role in
language.
Damage to Wernicke’s area results in language problems called
fluent aphasia.
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The Brain: A Closer Look
Broca’s and Wernicke’s aphasias are the two most common, but
there are other types.
For example, optic aphasia:
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The Brain: A Closer Look
Apraxias are deficits in nonverbal skills.
Apraxias involve damage to the right hemisphere.
Dressing apraxia:
Constructional apraxia:
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The Brain: A Closer Look
In addition to apraxias, the right hemisphere controls prosody,
the ability to express emotion.
People suffering from motor aprosodia:
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The Brain: A Closer Look
In the early 1960s, two neurosurgeons, Philip Vogel and Joseph
Bogen, discovered that cutting the corpus callosum reduced
seizures in untreatable epileptic patients.
Even though we do not know exactly why this operation controls
seizures, it is still performed as a last resort in severe cases of
epilepsy.
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The Brain: A Closer Look
Research by Nobel Prize winner Roger Sperry and his colleague
Michael Gazzaniga showed that in people with a severed corpus
callosum, the two hemispheres appeared to be doing different
things.
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The Brain: A Closer Look
Studies of split brain patients support the conclusion
that the left hemisphere…
Although the right hemisphere…
Neuroplasticity of the brain.
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