Brains, Bodies, and Behavior
Brains, Bodies, and Behavior
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The Neuron Is the Building Block of the Nervous System
Our Brains Control Our Thinking, Feeling, and Behavior
Psychologists Study the Brain Using Many Different Methods
Putting It All Together: The Nervous System and the Endocrine System
The Neuron Is the Building Block of the Nervous System
The Neuron Is the Building Block of the Nervous
System
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Learning Objectives
1.
Describe the structure and functions of the neuron
2.
Draw a diagram of the pathways of communication within and between neurons.
3.
List three of the major neurotransmitters and describe their functions.
The Neuron Is the Building Block of the Nervous
System
Major
Parts
of a
Neuron
Soma (Cell Body)
contains the cell’s nucleus
keeps the cell alive
Dendrite
collects information from other cells
sends the information to the soma
Axon
transmits information away from the cell body, toward other
neurons or muscles and glands
The Neuron Is the Building Block of the Nervous
System
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Specialized parts of an axon
– myelin sheath – layer of fatty tissue surrounding the axon
• insulates the axon
• speeds the transmission of the electrical signal
– terminal button – branching toward the end of an axon
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Image of a motor neuron, with dendrite,
axon and cell body labeled and described
Neurons Communicate Using Electricity and Chemicals
Within a Neuron
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Communication is electrical, taking the
form of a charge called an action potential
Between Neurons
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Communication is chemical, via
neurotransmitters which travel across the
gap between two neurons
Neurons Communicate Using Electricity and Chemicals
Resting Potential
the interior of a neuron is negatively charged relative to the
area outside the neuron
Action Potential
when an electrical signal is passed from the dendrites, the
neuron’s charge changes from negative to positive
Refractory Period
following an action potential, a neuron cannot fire again
for a brief time
Neurons Communicate Using Electricity and Chemicals
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The myelin sheath wraps around the axon,
but also leaves small gaps called the Nodes
of Ranvier.
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The action potential jumps from node to
node as it travels down the axon
Neurotransmitters: The Body’s Chemical Messengers
synapse
• areas where the terminal buttons at the end of
an axon nearly touch another neuron’s dendrites
neurotransmitter
• chemicals that relay signals across the synapses
between neurons
reuptake
• neurotransmitters in the synapse are reabsorbed
into the transmitting terminal buttons
Neurotransmitters: The Body’s Chemical Messengers
action potential
reaches terminal
button
neurotransmitter
release
neurotransmitters
bind to receptor
sites on dendrite
neurotransmitter
reuptake
neurotransmitters
travel across
synapse
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When the nerve impulse reaches the
terminal button, it triggers the release of
neuro-transmitters into the synapse.
The neuro-transmitters fit into receptors on
the receiving dendrites in the manner of a
lock and key
Neurotransmitters: The Body’s Chemical Messengers
Excitatory
neurotransmitters
– increase the
likelihood that a
neuron will fire
Inhibitory
neurotransmitters
– decrease the
likelihood that a
neuron will fire
Agonist
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Drug that mimics or enhances the influence
of a given neurotransmitter
– e.g., cocaine is a dopamine agonist
Antagonist
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Drug that blocks or inhibits the activity of a
given neurotransmitter
– e.g., curare is an acetylcholine
antagonist
Neurotransmitters: The Body’s Chemical Messengers
Neurotransmitters: The Body’s Chemical Messengers
The Neuron Is the Building Block of the Nervous
System
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Key Takeaways
– The Central Nervous System (CNS) is the collection of neurons that make up the brain and
the spinal cord.
– The Peripheral Nervous System (PNS) is the collection of neurons that link the CNS to our
skin, muscles, and glands.
– Neurons are specialized cells, found in the nervous system, which transmit information.
Neurons contain a dendrite, a soma, and an axon.
The Neuron Is the Building Block of the Nervous
System
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Key Takeaways, continued
– Some axons are covered with a fatty substance known as the myelin sheath which
surrounds the axon acting as an insulator, allowing faster transmission of the electrical
signal
– The dendrite is a treelike extension that receives information from other neurons and
transmits electrical stimulation to the soma.
– The axon is an elongated fiber that transfers information from the soma to the terminal
buttons.
The Neuron Is the Building Block of the Nervous
System
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Key Takeaways, continued
– Neurotransmitters relay information chemically from the terminal buttons and across the
synapses to the receiving dendrites using a type of lock and key system.
– The many different neurotransmitters work together to influence cognition, memory, and
behavior.
– Agonists are drugs that mimic the actions of neurotransmitters, whereas antagonists are
drugs that block the action of neurotransmitters.
Our Brains Control Our Thinking, Feeling, and
Behavior
Our Brains Control Our Thinking, Feeling, and
Behavior
Learning Objectives:
1.
Describe the structures and function of the “old brain,” and its influence on behavior.
2.
Explain the structure of the cerebral cortex (its hemispheres and lobes) and the function
of each area of the cortex.
3.
Define the concepts of brain plasticity, neurogenesis, and brain lateralization.
Our Brains Control Our Thinking, Feeling, and
Behavior
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The “Old Brain”
– Includes the brain structures nearest the spinal cord
– Regulates basic survival functions, such as breathing, moving, resting, and feeding
– Contributes to experiences of emotion
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In addition to the old brain, humans have a
large and highly developed outer brain
layer known as the cerebral cortex.
The cortex provides humans with excellent
memory, outstanding cognitive skills, and
the ability to experience complex
emotions.
The Old Brain: Wired For Survival
Brainstem
includes the medulla,
pons, and reticular
formation
thalamus
filters sensory
information from spinal
cord; relays information
to cortex
cerebellum
coordinates voluntary
movement
Limbic System
includes the amygdala,
hippocampus, and
hypothalamus
The Old Brain: Wired For Survival
The
Brainstem
Medulla
nearest the spinal cord
controls heart rate and breathing
Pons
helps control movement; plays a major role in balance and walking
Reticular Formation
filters stimuli from spinal cord
plays a role in eating, walking, sexual activity, and sleeping
The Old Brain: Wired For Survival
The Old Brain: Wired For Survival
The
Limbic
System
Amygdala
regulates our perceptions of and reactions to aggression and fear
Hippocampus
helps store information in long-term memory
Hypothalamus
links the nervous system to the endocrine system via the pituitary gland
helps regulate body temperature, thirst, hunger, and sexual motivation
The Old Brain: Wired For Survival
The Cerebral Cortex Creates Consciousness and
Thinking
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cerebral cortex – the outer, bark-like layer of the human brain that allows us to use language,
acquire complex skills, create tools, and live in social groups
– contralateral control – the left side of the cortex responds to and controls the right side of
the body, and vice versa
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The brain is divided into two hemispheres - left and right.
Each hemisphere has four lobes -temporal, frontal, occipital and parietal.
The Cerebral Cortex Creates Consciousness and
Thinking
Frontal Lobes
thinking, planning,
memory, and judgment;
contain motor cortex
Parietal Lobes
process touch information;
contain somatosensory
cortex
Temporal Lobes
Occipital Lobes
hearing and language;
contain auditory cortex
process visual information
and contain visual cortex
The Cerebral Cortex Creates Consciousness and
Thinking
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In addition to its motor and sensory areas, the cortex contains association areas.
In the association areas, sensory and motor information is combined and related to our stored
knowledge.
The Brain is Flexible: Neuroplasticity
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neuroplasticity – the brain’s ability to change its structure and function in response to
experience or damage
neurogenesis – the forming of new neurons
The Left and Right Hemispheres
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Brain Lateralization
– The left and right hemispheres are specialized to perform different functions.
– The corpus callosum is a band of fibers connecting the two hemispheres.
– Sperry’s research on split brain patients contributed to our understanding of brain
lateralization.
The Left and Right Hemispheres
Left Hemisphere
-- language
-- mathematics
-- judging time and
rhythm
--sequencing complex
movements
Corpus Callosum
connects left and right
hemispheres
Right Hemisphere
-- perceptual skills
-- recognizing objects
and faces
-- recognizing patterns
and melodies
-- drawing pictures
Our Brains Control Our Thinking, Feeling, and
Behavior
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Key Takeaways
– The old brain, including the brainstem, medulla, pons, reticular formation, thalamus,
cerebellum, amygdala, hypothalamus and hippocampus regulates basic survival functions
such as breathing, moving, resting, feeding, emotions and memory.
– The cerebral cortex, made up of billions of neurons and glial cells, is divided into the right
and left hemispheres and into four lobes.
– The frontal lobes are primarily responsible for thinking, planning, memory and judgment.
The parietal lobes are primarily responsible for bodily sensations and touch. The temporal
lobes are primarily responsible for hearing and language. The occipital lobes are primarily
responsible for vision. Other areas of the cortex act as association areas, responsible for
integrating information.
Our Brains Control Our Thinking, Feeling, and
Behavior
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Key Takeaways, continued
– The brain changes as a function of experience and potential damage in a process known as
plasticity. The brain can generate new neurons through neurogenesis.
– The motor cortex controls voluntary movements. Body parts requiring the most control and
dexterity take up the most space on the motor cortex.
– The sensory cortex receives and processes bodily sensations. Body parts that are the most
sensitive occupy the greatest amount of space on the sensory cortex.
– The left cerebral hemisphere is primarily responsible for language and speech in most
people, whereas the right hemisphere specializes in spatial and perceptual skills,
visualization, and the ability to recognize patterns, faces, and melodies.
Our Brains Control Our Thinking, Feeling, and
Behavior
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Key Takeaways, continued
– The severing of the corpus callosum, which connects the two hemispheres, creates a “split
brain patient,” with the effect of creating two separate minds operating in one person.
– Studies with split-brain patients as research participants have been used to study brain
lateralization.
– Neuroplasticity allows the brain to adapt and change as a function of experience or
damage.
Psychologists Study the Brain Using Many Different
Methods
Psychologists Study the Brain Using Many Different
Methods
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Learning Objective:
1.
Compare and contrast the techniques that scientists use to view and understand brain
structures and functions.
Psychologists Study the Brain Using Many Different
Methods
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Cadaver Approach
– The most direct approach to
understanding the structure of the
brain
Advantage
Disadvantage
brain can be
fully studied
the brain is no
longer active
Lesions Provide a Picture of What is Missing
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Lesions
– In living humans, lesions are areas of brain damage resulting from accidents, strokes,
gunshots, or other injuries.
– Lesions may also be created intentionally in animals.
– Lesions allow scientists to observe the loss of function that results.
Lesions Provide a Picture of What is Missing
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Areas in the frontal lobes of Phineas Gage
were damaged when a metal rod was
blasted through it.
Gage’s personality, emotions, and moral
reasoning were influenced.
The accident helped scientists understand
the role of the frontal lobes in these
processes.
Recording Electrical Activity in the Brain
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In animals, detectors can be placed in the brain to study the electrical activity caused by the
firing of specific neurons.
In living humans, the electrical activity of the brain’s neurons can be studied using scalp
electrodes – this is electroencephalography, or EEG.
Recording Electrical Activity in the Brain
Advantages of EEG
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Useful in understanding brain abnormalities
such as epilepsy
Participants can move around during
recordings
Allows changes to brain activity to be
tracked very quickly
Disadvantage of EEG
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Does not provide a clear picture of the
brain’s structure
Peeking Inside the Brain: Neuroimaging
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Functional Magnetic Resonance Imaging (fMRI)
– a type of brain scan that uses a magnetic field to create images of the activity in each
brain area
– detects the blood flow in each brain region
– currently the most common method of learning about brain structure
Peeking Inside the Brain: Neuroimaging
Advantages of
fMRI
Disadvantage of
fMRI
provides detailed
pictures of brain
structures
scanners are
expensive
non-invasive
Peeking Inside the Brain: Neuroimaging
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Transcranial Magnetic Stimulation (TMS)
– procedure in which magnetic pulses are applied to a living person’s brain to temporarily
and safely deactivate a small brain area
– allows cause-and-effect conclusions about the influence of brain structures on thought and
behavior
Psychologists Study the Brain Using Many Different
Methods
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Key Takeaways
– Studying the brains of cadavers can lead to discoveries about brain structure, but are
limited due to the fact that the brain is no longer active.
– Lesion studies are informative about the effects of different brain regions.
– Electrophysiological recording may be used in animals to directly measure brain activity.
Psychologists Study the Brain Using Many Different
Methods
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Key Takeaways, continued
– Measures of electrical activity in the brain, such as electroencephalography (EEG) are used
to assess brainwave patterns and activity.
– Functional Magnetic Resonance Imaging (fMRI) measures blood flow in the brain during
different activities, providing information about the activity of neurons and thus the
functions of brain regions.
– Transcranial Magnetic Stimulation (TMS) is used to temporarily and safely deactivate a
small brain region, with the goal of testing the causal effects of the deactivation on
behavior.
The Nervous System and The Endocrine System
The Nervous System and The Endocrine System
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Learning Objectives:
1.
Summarize the primary functions of the CNS and of the subsystems of the PNS.
2.
Explain how the electrical components of the nervous system and the chemical
components of the endocrine system work together to influence behavior.
Electrical Control of Behavior: The Nervous System
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Nerves
– bundles of interconnected neurons
that fire in synchrony
sensory (afferent)
neurons
carry information from
the sensory receptors
motor (efferent)
neurons
transmit information to
the muscles and glands
interneurons
communicate
information among
neurons
Electrical Control of Behavior: The Nervous System
Central
Nervous
System
Brain
Spinal Cord
Electrical Control of Behavior: The Nervous System
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Reflexes – involuntary, nearly
instantaneous movements in response to
stimuli
Triggered when powerful sensory
information allows spinal cord interneurons
to send a message back through the motor
neurons without relaying the information to
the brain
Electrical Control of Behavior: The Nervous System
Peripheral Nervous
System
connects CNS to sense
receptors, glands, and
muscles
Autonomic Nervous
System
governs bodies internal
activities
Sympathetic Nervous
System
Somatic Nervous System
controls external aspects
of the body
Parasympathetic Nervous
System
Electrical Control of Behavior: The Nervous System
Sympathetic Nervous System
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Prepares the body for action, especially in
response to stress
Activates the organs and the glands in the
endocrine system
Parasympathetic Nervous
System
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Calms the body
Slows heart rate and respiration
Allows the body to recover from action
The Body’s Chemicals Help Control Behavior: The
Endocrine System
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glands
secrete
hormones
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Endocrine System
– glands – cell groups
– hormones – chemicals circulating in
the body to regulate emotion and
behavior
The endocrine system interacts with the
nervous system.
The Body’s Chemicals Help Control Behavior: The
Endocrine System
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Pituitary Gland
– small gland in the center of the brain
– the “master gland”
– secretes hormones that influence
responses to pain
– secretes hormones that signal the
ovaries and testes to make sex
hormones
– controls ovulation and the menstrual
cycle in women
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Adrenal Glands
– located on top of the kidneys
– produce hormones that regulate
body’s salt and water balance
– involved in metabolism, the immune
system, and sexual development and
function
– secrete the hormones epinephrine and
norepinephrine when we are excited
or threatened
• Epinephrine and norepinephrine
stimulate the sympathetic
nervous system
The Body’s Chemicals Help Control Behavior: The
Endocrine System
pancreas
secretes hormones
to supply body with
energy
pineal gland
secretes melatonin
to regulate sleep
cycle
The Body’s Chemicals Help Control Behavior: The
Endocrine System
Testes (Male Sex Glands)
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Secrete Testosterone
– Testosterone regulates body changes
related to sexual development.
– Testosterone levels are positively
associated with aggressive behavior in
both men and women.
Ovaries (Female Sex Glands)
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Secrete Estrogen and Progesterone
– Estrogen is involved in the
development of female sexual
features.
– Both hormones are involved in
pregnancy and the regulation of the
menstrual cycle.
The Nervous System and The Endocrine System
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Key Takeaways
– The body uses both electrical and chemical systems to create homeostasis.
– The CNS is made up of bundles of nerves that carry messages to and from the PNS
– The Peripheral Nervous System is comprised of the Autonomic Nervous System (ANS) and
the Peripheral Nervous System (PNS). The ANS is further divided into the sympathetic
(activating) and parasympathetic (calming) nervous systems. These divisions are activated
by glands and organs in the endocrine system.
– Specific nerves, including sensory neurons, motor neurons, and interneurons, each have
specific functions.
The Nervous System and The Endocrine System
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Key Takeaways, continued
– The spinal cord may bypass the brain by responding rapidly using reflexes.
– The pituitary gland is a master gland affecting many other glands.
– Hormones produced by the pituitary and adrenal glands regulate growth, stress, sexual
functions, and chemical balance in the body.
– The adrenal glands produce epinephrine and norepinephrine, the hormones responsible for
our reactions to stress.
– The sex hormones, testosterone, estrogen, and progesterone play an important role in sex
differences