Transcript What is Psychology?

Invitation To Psychology
Carol Wade and Carol Tavris
PowerPoint Presentation by
H. Lynn Bradman
Metropolitan Community College-Omaha
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Neurons, Hormones, and the
Brain
Chapter 4
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Neurons, Hormones, and the
Brain
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The Nervous System: A Basic Blueprint
Communication in the Nervous System
Mapping the Brain
A Tour Through the Brain
The Two Hemispheres of the Brain
Two Stubborn Issues in Brain Research
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The Nervous System: A Basic
Blueprint
The Central Nervous System
The Peripheral Nervous System
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Divisions of the Nervous System
• Central Nervous
System
– Brain
– Spinal cord
• Peripheral
Nervous System
– Somatic
– Autonomic
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Nervous System
Organization
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The Central Nervous System
• Central Nervous System: The portion of
the nervous system consisting of the
brain and spinal cord.
• Spinal Cord: A collection of neurons and
supportive tissue running from the base
of the brain down the center of the back,
protected by a column of bones (the
spinal column).
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The Peripheral Nervous
System
• Somatic Nervous System: The
subdivision of the PNS that connects to
sensory receptors and to skeletal
muscles; sometimes called the skeletal
nervous system.
• Autonomic Nervous System: The
subdivision of the PNS that regulates the
internal organs and glands.
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Sympathetic and
Parasympathetic
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Communication in the Nervous
System
The Structure of the Neuron
How Neurons Communicate
Chemical Messengers in the
Nervous System
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Different Kinds of Neurons
• Neurons vary in size and shape, depending on
their location and function. More than 200
types have been identified in mammals.
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The Structure of the Neuron
• Dendrite: Branches that
receive signals and
transmit to cell body
• Cell Body: Controls cell
metabolism and
determines firing
• Axon: Carries impulses
away from cell body
• Myelin Sheath: Fatty
insulation
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How Neurons Communicate
• Synapse: Site where a nerve impulse is
transmitted from one neuron to another;
includes the axon terminal, synaptic
cleft, and receptor sites on receiving cell.
• Neurotransmitter: Chemical substance
that is released by transmitting neuron
at the synapse and alters the activity of
the receiving neuron.
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Plasticity in Brain & 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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Getting Connected
• Neurons in a newborn’s brain are widely
spaced, but form connections quickly.
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Chemical Messengers in the
Nervous System
• Neurotransmitters
are released into
synaptic cleft
• Bind to receptor site
on receiving neuron
• Electrical state of
receiving neuron
changes, becoming
more (or less) likely
to fire
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Major Neurotransmitters
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Acetylcholine (ACh)
Dopamine
Serotonin
Norepinephrine
Gamma amino butryic acid (GABA)
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Endorphins
• Chemical substances in the nervous
system that are similar in structure and
action to opiates; they are involved in
pain reduction, pleasure, and memory,
and are known technically as
endogenous opioid peptides.
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Hormones
• Hormones: Chemical substances,
secreted by organs called glands, that
affect the functioning of other organs.
• Endocrine Glands: Internal organs that
produce hormones and release them into
the bloodstream.
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Mapping the Brain
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Electroencephalogram
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Positron Emission
Tomography
• Active areas have
increased blood flow
• Radioactive isotopes
(small amounts) are
placed in the blood
• Sensors detect
radioactivity
• Different tasks show
distinct activity patterns
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Magnetic Resonance
Imaging
• Magnetic fields align certain
ions and compounds
• When field is removed,
these molecules release
energy as radio waves
• Computer calculates tissue
density from radio waves
• Provides clear, 3D images
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A Tour Through the Brain
The Brain Stem
The Cerebellum
The Thalamus
The Hypothalamus and the Pituitary
Gland
The Limbic System
The Cerebrum
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The Human Brain
• This view shows the
brain as if split in
half front-to-back
– Inside surface of right
half of brain
– Eyes on the left, near
the word
“hypothalamus”
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The Brain Stem
• Brain Stem: At the top of the
spinal cord, consisting of
medulla and pons
– Medulla: Responsible for
some automatic functions,
such as breathing and heart
rate
– Pons: Involved in sleep,
waking, and dreaming.
– Reticular Activating System:
A dense network of neurons
found in the core of the brain
stem; it arouses the cortex
and screens incoming
information.
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The Cerebellum
• Cerebellum: Regulates movement and
balance, and is involved in learning
some simple responses.
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Thalamus and Hypothalamus
• Thalamus: Relays sensory messages to
the cerebral cortex.
• Hypothalamus: Involved in emotions
and drives vital to survival (e.g., fear,
hunger, thirst, and reproduction); it
regulates the autonomic nervous
system.
• Pituitary Gland: Small endocrine gland
at the base of the brain, which releases
many hormones and regulates other
endocrine glands.
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The Limbic System
• Limbic System: A group of
brain areas involved in
emotional reactions and
motivated behavior.
• Amygdala: Involved in the
arousal and regulation of
emotion and the initial
emotional response to
sensory information.
• Hippocampus: Involved in
the storage of new
information in memory.
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The Cerebrum
• Occipital Lobes:
Vision
• Parietal Lobes: body
sensation
• Temporal Lobes:
Hearing, language
• Frontal Lobes:
Thinking, planning,
movement
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The Case of Phineas Gage
• Gage was a railroad
construction foreman
• An 1848 explosion
forced a steel
tamping rod through
his head
• Others said he was
“…no longer Gage…”
• Lost his job, worked
as a sideshow exhibit
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The Two Hemispheres of the
Brain
Split Brains: A House Divided
A Question of Dominance
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Visual Pathways
• Each hemisphere
receives information
about the opposite
side of the visual field.
• Objects to your left put
images on right side of
each retina; goes to
right side of brain
• Half of optic nerve
fibers cross at the
optic chiasm
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Split Brains: A House
Divided
• Hemispheres of brain sometimes
separated to treat severe epilepsy
• Split brain operation includes the optic
chiasm
– Optic nerve no longer crosses
– Visual information goes only to one
hemisphere
• Different sides of brain see different
information
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Divided Brain, Divided View
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Two Stubborn Issues in Brain
Research
Why Do We Dream?
Are There “His” and “Hers”
Brains?
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Why Do We Dream?
• Rapid Eye Movement (REM) Sleep: Sleep
periods characterized by fast eye
movement behind closed eyelids, loss of
muscle tone, and dreaming.
• Activation-Synthesis Theory: Theory that
dreaming results from cortical synthesis
and interpretation of neural signals
triggered by activity in the lower part of
the brain.
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Are There “His” & “Hers”
Brains?
• Sex differences in the brain have
been studied for many years.
– Many findings seem to reflect
cultural bias, and change with
cultural changes
• Reliable differences have been
found in activity of certain brain
areas during some tasks
– Example: MRI of language task,
right
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♂
♀
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