Download Chapter 2

4th Edition
Psychology
Stephen F. Davis
Emporia State University
Joseph J. Palladino
University of Southern Indiana
PowerPoint Presentation by H. Lynn Bradman
Metropolitan Community College-Omaha
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Chapter 2
4th Edition
Behavioral
Neuroscience
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The Evolutionary Perspective
• The evolutionary perspective stresses the
role of physiological structures and
behaviors in an organism's adaptation to
the environment and ultimate survival.
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Natural Selection
• The principle of natural selection states
that the most fit organisms survive
because they adapt best to the
environment and thus pass on their genes
to future generations.
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Biology and Behavior
• The term behavioral neuroscience
describes the work of scientists from
several disciplines who work to
understand how the nervous system is
related to behavior.
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The Nervous System
• We use the processes of sensing,
processing, and responding to interact
with the environment.
• The nervous system is divided into the
central nervous system (CNS-brain and
spinal cord) and the peripheral nervous
system (PNS-all parts of the nervous
system outside the CNS), coordinates
these three activities.
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The Nervous System
• The nervous
system is divided
into the central
nervous system
(CNS-brain and
spinal cord) and
the peripheral
nervous system
(PNS-all parts of
the nervous system
outside the CNS),
coordinates these
three activities.
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The CNS
• The spinal cord is
composed of sensory
(afferent or
ascending) and motor
(efferent or
descending) nerves.
• Interneurons may
connect sensory and
motor neurons.
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CNS Nerves
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The PNS
• The PNS is composed of the somatic
division and the autonomic division.
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The PNS
• The somatic division consists of afferent
(sensory) nerves that run from the
receptors to the brain and efferent (motor)
nerves that run to the glands and muscles.
• The autonomic division consists of the
sympathetic division, which mobilizes the
body's resources, and the
parasympathetic division which returns the
body to a normal state of homeastasis.
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Divisions of the Nervous System
• Central Nervous
System
– Brain
– Spinal cord
• Peripheral Nervous
System
– Somatic
– Autonomic
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The Endocrine System
• The endocrine system affects behavior by
producing and secreting hormones, which
are chemicals that regulate body
functions.
• Among the major endocrine glands are the
pineal gland, hypothalamus pituitary gland,
the thyroid gland, the pancreas, the
gonads, and the adrenal glands.
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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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Neurons: The Basic Cells
• 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
– terminal buttons that contain
neurotransmitters.
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Structure of a Neuron
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Neurotransmitters
• Neurotransmitters enable the signal from
one neuron to be relayed to other neurons
across the synapse, a small gap that
separates neurons.
• A myelin sheath covers the axons of some
neurons to increase the speed of
transmission of the neural signal.
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The Synapse
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Key Neurotransmitters
•
•
•
•
•
•
Acetylcholine (ACh)
Dopamine
Serotonin
Endorphins
Norepinephrine
Gamma amino butryic acid (GABA)
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Neurotransmitters
• Among the key neurotransmitters,
dopamine has been implicated in the
development of Parkinson's disease.
• Acetycholine seems to play a role in
Alzheimer's disease.
• Serotonin has been implicated In a variety
of disorders, including depression and
obsessive-compulsive disorder.
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How Neurons Communicate
• Ions (electrically charged particles) are
found on the inside and outside of the
neuron's semi-permeable cell membrane
• When a neuron is in a resting state, more
negative ions are on the inside of the cell
(measured at -70 mV) than on the out
side.
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How Neurons Communicate
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How Neurons Communicate
• Neurotransmitters stimulate the cell
membrane to allow ions to enter the
neuron resulting in:
– depolarization (positive ions move inside the
neuron resulting in excitation) or
– hyperpolarization (additional negative ions
move inside resulting in in hibition).
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How Neurons Communicate
• If depolarization of the dendrite and soma
reaches the threshold level (-65 to -60
mV), the axon quickly reverses electrical
charge (to about +40 mV), and the signal
is transmitted to the next neuron.
• This reversal in electrical charge known as
the action potential.
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The Action Potential
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How Neurons Communicate
• Neurotransmitters must be removed from
the synapse be fore another signal can be
transmitted.
• Removal is accomplished either by
destroying the neurotransmitter
(breakdown) or by taking it back into the
terminal buttons (reuptake).
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Neuromodulators
• Neuromodulators have more widespread
and indirect effects than neurotransmitters.
• Neuromodulators also influence
transmission between cells.
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Agonists and Antagonists
• Agonists are drugs that promote the action
of a neurotransmitter.
• Antagonists are drugs that oppose or
inhibit the action of a neurotransmitter.
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Agonists and Antagonists
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Agonists and Antagonists
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The Brain: A Closer Look
• Phrenology is a
pseudoscience
popularized in the
1800s by Franz
Joseph Gall
• Gall believed we
could determine a
person's skills and
characteristics by
identifying bumps on
the skull.
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The Brain: A Closer Look
• Early studies of brain functioning involved
stimulating or removing portions of the
cortex.
• The stereotaxic instrument allowed
examination of subcortical structures
without damaging the cortex.
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The Brain: A Closer Look
• The electroencephalograph (EEG)
provides an investigator with a chart of a
person's brain waves.
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The Brain: A Closer Look
• lmages of the structures of the brain can
be produced by computerized techniques
such as:
– the PET (positron emission tomography),
– the CT or CAT (computerized axial
tomography),
– the MRI (magnetic resonance imaging),
– and the fMRl (functional magnetic resonance
imaging).
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The Brain
• The brain is divided
into the hindbrain, the
midbrain, and the
forebrain.
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The Hindbrain
• The oldest of the three main divisions of
the brain.
• Its major structures are the medulla, pons,
and cerebellum.
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The Midbrain
• A major division of the brain that contains
fibers known as the reticular formation.
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The Forebrain
• A major division of the brain that consists
of subcortical structures and the two
hemispheres of the cerebral cortex.
• The hemispheres of the cerebral cortex
are joined by the corpus collosum.
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The Corpus Callosum
• Millions of myelinated axons connecting the
brain’s hemispheres.
• Provides a pathway for communication between
the hemispheres.
• If surgically severed for treatment of epilepsy,
hemispheres cannot communicate directly.
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The Cortex
• The cerebral cortex covers the forebrain
and is divided into four lobes:
– frontal,
– parietal,
– temporal,
– and occipital.
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Lobes of the Cerebral Cortex
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Subcortical Structures
• A group of subcortical
structures involved in
emotion, memory,
eating, drinking, and
sexual behavior are
located beneath the
cortex.
• These structures
include the limbic
system, thalamus,
and hypothalamus.
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More About the Brain
• The brain has been described as plastic,
which means it can change over time and
recover to some degree even from
removal of an entire hemisphere.
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Plasticity in Brain and Behavior
• Some rats are housed alone in empty cages
• Their littermate twins are group-housed in cages
with toys, which are changed frequently
• Richer environments led to heavier, thicker
brains, more synapses, and better learning
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More About the Brain
• Studying the human brain yields
information about aphasias (language
deficits) and apraxias (nonverbal deficits).
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Sperry’s Split-Brain Experiment
• Split-brain subjects could not name
objects shown only to the right hemisphere
• If asked to select these objects with their
left hand, they succeeded
• The right side of the brain doesn’t control
speech
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