Psychology (8th Edition) – David Myers
Chapter 2 – Neuroscience and Behavior
Everything psychological is also biological.
The brain is not completely understood.
 How does our brain organize and communicate with itself?
 How do our heredity and our experiences together wire our brain?
 How do memories work in the brain?
Plato correctly located the mind in the spherical head.
Aristotle believed the mind was in the heart, which pumps warmth and vitality to the body.
Early 1800s – Franz Gall (German physician) invented phrenology – a popular but ill-fated theory that claimed bumps
on the skull could reveal our mental abilities and our character traits. Phrenology correctly focused attention on the
idea that various brain regions have particular functions.
In the last century, scientists have discovered that the body is made of cells. Nerve cells conduct electricity to “talk” to
one another by sending chemical messages across a tiny gap that separates them.
Biological psychology – a branch of psychology concerned with the links between biology and behavior.
Neural Communication
 We are all biopsychological systems.
o We are each a system composed of subsystems that are in turn composed of even small subsystems
Neurons
 Neuron – a nerve cell; the basic building block of the nervous system
o Building blocks of the neural information system
 Dendrites – the bushy branching extensions of a neuron that receive messages and conduct impulses toward
the cell body.
 Axon – the extension of a neuron, ending in branching terminal fibers, through which messages pass to other
neurons or to muscles or glands.
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Axons speak, dendrites listen.
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Myelin sheath – a layer of fatty tissue segmentally enhancing the fibers of many neurons; enables vastly
greater transmission speed of neural impulses as the impulse hops from one node to the next.
o protection
o speed
Axon terminal – branches at the end of an axon that send messages to the dendrites of another neuron
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A neuron fires an impulse when it receives a signal from sense receptors or by chemical messages from
neighboring neurons.
o Action potential - a neural impulse down the axon
Neurons generate electricity from chemical reactions – involves the exchange of electrically charged atoms
(ions).
o fluid inside an axon = negatively charged ions.
o fluid outside an axon = positively charged ions.
o Positive/outside – negative/inside state is called the resting potential
Steps in chemistry to electricity change…
o Neuron receives chemical message
o Axon admits positively charged sodium ions through the membrane  domino effect
o During a resting pause (refractory period) the axons recharge by pushing the positively charged ions back
outside  then it can fire again.
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Threshold – the level of stimulation required to trigger a neural impulse.
o All-or-nothing; fires or doesn't
How Neurons Communicate
 Neurons are separated by gaps less than a millionth of an inch wide.
o Synapse – the junction between the axon tip of the sending neuron and the dendrite or cell body of the
receiving neuron; tiny gap called the synaptic gap or cleft.
 Neurons communicate across the synaptic gap by using
neurotransmitters – chemical messengers that traverse the
synaptic gaps between neurons.
o When the action potential reaches the axon’s terminal
buttons, these branches release chemicals/neurotransmitters
that travel across the synaptic gap and bind/connect to
receptor sites on the receiving neuron’s dendrites - lockand-key relationship.
o When a neuron receives neurotransmitters the neuron will
fire and the action potential will travel down its axon.
Communication within the neuron - ELECTRICAL
Communication between neurons - CHEMICAL
How Neurotransmitters Influence Us
 Different neurotransmitters are found in different parts of the brain.
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Neurotransmitters also compel humans to feel and experience certain emotions/behaviors.
Neurotransmitter
Acetylcholine
(ACh)
Dopamine
Serotonin
Norepinephrine
GABA (gammaaminobutyric acid)
Glutamate
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SOME NEUROTRANSMITTERS AND THEIR FUNCTIONS
Function
Examples of Malfunction
Enables muscle action,
Alzheimer’s disease – ACh producing neurons deteriorate.
learning, and memory.
Influences movement, learning, Excess dopamine receptor activity is linked to schizophrenia.
attention, and emotion.
Too little dopamine in the brain can lead to Parkinson’s disease
(tremors and decreased mobility).
Affects mood, hunger, sleep,
Too little serotonin is linked to depression. (Anti-depression
and arousal
drugs raise serotonin levels)
Helps control alertness and
Too little can depress mood
arousal
A major inhibitory
Too little can lead to seizures, tremors, and insomnia.
neurotransmitter
A major excitatory
Too much can overstimulate the brain – producing migraines or
neurotransmitter – involved in
seizures
memory
A study in 1973 (on animals) showed that morphine (an opiate drug used to decrease pain and elevate mood)
bound to the same receptor sites in areas linked with mood and pain sensations  why would the brain have
“opiate receptors” if it did not naturally produce opiate-like neurotransmitters?
o Endorphins – natural, opiate-like neurotransmitters linked to pain control and pleasure.
How Drugs and Other Chemicals Alter Neurotransmission
 When the brain is flooded by certain neurotransmitters in the form of medication or drugs (cocaine, heroin,
morphine), it may naturally stop producing similar transmitters. When the medication or drug is withdrawn, the
brain may be deprived of any form of opiates until the brain can naturally start producing its own
neurotransmitters again.
o Explains the uncomfortable withdrawal period when a drug addict ceases using the drug.
 Various drugs and substances can effect communication at the synapse, by exciting or inhibiting a neuron to fire.
o Agonist – molecules that are similar to neurotransmitters and can mimic their effects.
 Eg: the venom of a black widow spider floods the brain with agonists similar to ACh which
results in muscle contractions, convulsions, and even death.
o Antagonist – a molecule that inhibits a neurotransmitter’s release
INTERACTIVE NEURON
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Eg: Botulin (a poison in improperly canned food), causes paralysis by blocking the release of
ACh from the sending neuron.
The Nervous System
 Nervous system – the body’s speedy electrochemical communication network, consisting of all the nerve cells
of the peripheral and central nervous systems.
o Central nervous system (CNS) – the brain and spinal cord
o Peripheral nervous system (PNS) – the sensory and motor neurons that connect the CNS to the rest of
the body.
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Nerves – part of the PNS; neural “cables” containing many axons; connect the CNS with muscles, glands, and
sense organs.
o Eg: the optic nerve is a bundle of millions of axon fibers that carry information from each eye to the
brain.
Information travels though the nervous system in 3 types of neurons.
o Sensory neurons – carry incoming information from the sense receptors to the CNS
o Interneurons – CNS neurons that internally communicate and intervene between the sensory inputs and
motor outputs
o Motor neurons – carry outgoing information from the CNS to the muscles and glands
The Peripheral Nervous System
 Somatic nervous system – controls the body’s skeletal muscles
o Eg: Running, dancing, movement
 Autonomic nervous system – controls the glands and the muscles of the internal organs; divided into the
sympathetic and parasympathetic nervous systems
o Eg: heartbeat, digestion, sweating
o Sympathetic nervous system – arouses the body
o Parasympathetic nervous system – calms the body
The Central Nervous System
The Spinal Cord and Reflexes
 The CNS is the highway/connector between the brain and the PNS.
 Sometimes, the body can react without the message having to travel all the way to the brain.
o Reflex – simple, autonomic, inborn response to a sensory stimulus, such as the knee-jerk response.
o Reflex pathway = 1 sensory neuron + 1 communication interneuron + 1 motor neuron
 If the spinal cord were to be severed, no sensations could reach the brain and the brain could not send out any
information.
o Simple reflexes like the knee-jerk would occur, but without the feeling of the tap. Simple pain reflexes
would not occur. Pain would also not reach the brain. However, other simple reflexes, like sexual arousal,
may still occur. Each spinal injury is unique to its affected reflexes and senations.
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Neurons, in the brain, cluster to work in groups to produce shorter, faster connections. Neurons can receive and
send information from and to many neurons at the same time.
o Neural networks – interconnected neural cells; with experience, networks can learn and strengthen
o Experience causes neural networks to grow and strengthen  eg: practicing the piano builds neural
connections that help this behavior.
The Endocrine System
 Endocrine System – the body’s “slow” chemical communication system; a set of glands that secrete hormones
into the bloodstream.
 Hormones – chemical messengers, mostly those manufactured by the endocrine glands that are produced in
one tissue and affect another.
o Travel slowly through the bloodstream between tissues
o When hormones act on the brain, they can trigger interest in sex, food, and aggression.
 Neurotransmitters : nervous system :: hormones : endocrine system.
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The endocrine system tries to keep a balance in the body while we respond to feelings of stress, anger, fear,
exertion, etc.
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Adrenal glands – a pair of endocrine glands above the kidneys; secrete the hormones epinephrine (adrenaline)
and norepinephrine (noradrenaline) which help to arouse the body in times of stress.
o Increase heart rate, blood pressure, and blood sugar that provide a surge of energy.
o Hormones and the feelings they produce can linger after the event which caused the release of the
hormone.
Pituitary gland – the endocrine system’s most influential gland; under the influence of the hypothalamus, it
regulates growth and controls other glands
o Pea-sized, in the core of the brain
o Controlled by the hypothalamus
o “master gland”
o Brain  pituitary gland  other glands  hormones  brain
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The Brain
Tools of Discovery
 Lesion – tissue destruction; can be naturally caused (accident, birth defect) or can be experimental
o what areas perform what function
 Clinical observation – observing the effects of specific brain diseases and injuries
o Can provide clues to how the brain functions in “normal” people
 Manipulating the brain – do not have to wait for brain injuries; can electrically, chemically, or magnetically
stimulate the brain and note the effects.
 Recording the brain’s electrical activity
o Electrical activity in the brain’s billions of neurons occur in regular waves across the its surface
o Electroencephalogram (EEG) – an amplified recording of the waves of electrical activity that sweep
across the brain’s surface; measured by electrodes placed on the scalp
 Works by presenting a stimulus repeatedly and having a computer filter out brain activity
unrelated to the stimulus, thus identifying the wave evoke provoked by the stimulus
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Neuroimaging techniques
o PET (positron emission tomography) scan – a visual display of brain activity that detects where a
radioactive form of glucose goes while the brain performs a given task.
 Active neurons use glucose. When the radioactive neurons are in the brain, the PET scan can pick
up their location, thus allowing us to see what areas of the brain perform certain tasks.
 “hot spots” = activity
o
MRI (magnetic resonance imaging) – a technique that uses magnetic fields and radio waves to
produce computer-generated images that distinguish among different types of soft tissue, allowing us
to see structures within the brain.
 The head is put in a strong magnetic field which aligns the spinning atoms. Then a brief pulse of
radio waves disorients the atoms. When they begin to spin again, they release signals that provide
images of their concentrations, resulting in an image of the brain’s tissues.
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fMRI (functional MRI) – a technique for revealing blood flow and therefore, brain activity by
comparing successive MRI scans.
 MRI scans show brain anatomy while fMRI scans show brain function.
Older Brain Structures
 A species’ brain size does not necessarily dictate intelligence, however the brain’s structure and complexity does
indicate intelligence and functioning.
The Brainstem – the oldest part and central core of the brain, beginning where the spinal cord swells as it enters the
skull; the brainstem is responsible for automatic survival functions
 Medulla – the base of the brainstem; controls heartbeat and breathing
 Pons – helps coordinate movement
 The brainstem is also the crossover point, where many nerves from each side of the brain connect.
 Reticular formation – a nerve network in the brainstem that plays an important role in controlling arousal
o In the brainstem, between the ears
o Extends from the spinal cord to the thalamus
o When stimulated, the reticular formation arouses you into alertness. If severed, you could enter a coma
and be unresponsive.
Thalamus – the brain’s sensory switchboard, located on top of the brainstem; it directs messages to the sensory
receiving areas in the cortex and transmits replies to the cerebellum and medulla
 Joined pair of egg-like structures
 Receives information from all senses (except smell) and routes it to the brain regions that deal with seeing,
hearing, tasting, and touching.
 Like the “brain’s train station” that receives routes and redirects them to their destination.
Cerebellum – the “little brain” attached to the rear of the brainstem; its functions include processing sensory input
and coordinating movement output and balance.
 Baseball-sized, two wrinkled halves
 People with injured cerebellums have difficulty walking and keeping balance; movements are jerky and
exaggerated.
*** These “older” brain functions all occur without any conscious effort – our brain processes information outside
of our awareness. ***
The Limbic System – a doughnut-shaped system of neural structures at the border of the brainstem and cerebral
hemispheres; associated with EMOTIONS such as fear and aggression and drives such as those for food and sex;
includes the hippocampus, amygdala, and hypothalamus.
 Hippocampus – processes memories
 Amygdala – two lima bean-sized neural clusters that are linked to emotion
o A monkey’s amygdala is lesioned  a normally ill-tempered monkey would turn very mellow despite
instigation.
o Normally calm, domestic animals (cat) would cower in fear of mouse if the amygdala was stimulated or
manipulated with electricity.
 Hypothalamus – a neural structure lying below the thalamus; directs some maintenance activities (eating,
drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to
emotion.
o Eg: thinking about sex can stimulate your hypothalamus to secrete hormones, which tell the pituitary
gland to influence the hormone release from other glands
The Cerebral Cortex – the intricate fabric of interconnected neural cells that covers the cerebral hemispheres; the
body’s ultimate control and information-processing center
 Like bark on a tree – a thin surface layer on the cerebral (brain) hemispheres
 Contains 20-23 billion nerve cells supported by nine times as many glial cells
o Glial cells – “glue cells;” cells in the nervous system that support, nourish, and protect neurons
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Lobes – geographical subdivisions of the cerebral cortex separated by prominent fissures (folds) in the
brain.
Lobe
Frontal
Parietal
Occipital
Temporal
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LOBES OF THE BRAIN AND THEIR FUNCTIONS (FPOT)
Where in Cerebral Cortex?
Function
Behind the forehead
Involved in speaking, muscle movements, and making plans/judgments
At the top of the head,
Receives sensory input for touch and body position
towards the rear
At the back of the head
Includes the visual areas, which receive visual information from the
opposite visual field
Roughly above the ears
Includes auditory areas, each of which receive auditory information
primarily from the opposite ear
Each lobe carries out many functions and many functions require the interplay of several lobes.
Motor functions
 motor cortex - an area at the rear of the frontal lobes that control voluntary movements.
o sends outgoing movements
o stimulation will cause different parts of the body to move
Sensory functions
 sensory cortex - the area at the front of the parietal lobes that registers and processes body touch and
movement sensations.
o parallel to the motor cortex, behind it at the front of the parietal lobe
o stimulation to the sensory cortex will make the patient feel like they are being touched depending on what
section of the sensory cortex is stimulated.
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The more sensitive a body region, the larger the area in the sensory cortex. (eg: lips are more sensitive, therefore
their corresponding area in the sensory cortex is larger than other regions)
Sight is processed in the occipital lobe in the visual cortex.
Sounds heard are processed in the temporal lobe in the auditory cortex.
Association Areas - 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.
 any area of the cerebral cortex that is not the motor cortex, sensory cortex, visual cortex, or auditory cortex.
 found in all four lobes
o frontal lobe association areas
 judgment, plans, processing new memories; damage to the frontal
lobe can hinder these activities and also change personality by
removing a person's inhibitions (eg: Phineas Gage had a metal rod
enter is head and pass through the frontal lobe in 1847. He survived
but his once calm and polite nature was gone, replaced with
irritability and dishonesty - loss of moral compass)
o
o
parietal lobe association areas
 math and spatial reasoning (large and unusually shaped in Einstein's brain)
temporal lobe association areas
 face recognition
Language
 aphasia - impairment of language, usually caused by left hemisphere damage either to Broca's area (speech) or
Wernicke's area (understanding)
o people suffering from aphasia may be able to read but not write, write but not read, read but not speak,
speak but not read, read numbers but not letters… it depends on what part of the brain is damaged.
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Broca's area - part of the cerebral cortex that controls language expression; in the frontal lobe, usually in the
left hemisphere, that directs the muscle movement involved in speech.
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Wernicke's area - part of the cerebral cortex that controls language reception; involved in language
comprehension and expression; usually in the left temporal lobe.
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How we use language… when you read aloud, 1) the words register in the visual area, 2) are relayed to a second
brain area, the angular gyrus, which transforms the words into an auditory code that is 3) received and understood
by the Wernicke's area, and 4) sent to Broca's area, which 5) controls the motor cortex as it creates the
pronounced word.
o The type of aphasia depends on which chain in the series is damaged
*** The brain uses specialization and integration to function.***
The Brain's Plasticity
 the brain is sculpted by our genes but also by our experiences.
 Brain plasticity - the brain's capacity for modification, as evident in brain reorganization following damage
(especially in children) and in experiments on the effects of experience on brain development.
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most neurons will never regenerate if damaged or killed, and many brain functions are preassigned to certain areas
that if damaged will affect the person's ability for the rest of their life… but some neural tissue can reorganize
after damage as the brain repairs itself after damage.
o eg: if you lose a finger, the sensory cortex reorganizes and receives information from the other fingers
which all in turn become more sensitive.
Blindness
o when reading Braille, the brain area dedicated to that finger expands as the sense of touch invades the
visual cortex, which normally helps people see
Deafness
o the auditory cortex receives no information from sound, so it expands to new functions like visual tasks,
which is why deaf people have been found to have enhanced peripheral vision.
Our Divided Brain
 the brain's two hemispheres have different functions
o Left hemisphere - "dominate" or "major" hemisphere, controls reading, writing, speaking, mathematic
reasoning, and understanding
o Right hemisphere - "subordinate" or "minor" hemisphere, controls insight, imagination
 corpus callosum - the large band of neural fibers connecting the two brain hemispheres and carrying
information between them.
o when severed, patients can function like before the damage (can eliminate seizures) but the two
hemispheres could not communicate
 split brain - a condition in which the two hemispheres of the brain are isolated by cutting the connecting fibers
(mainly the corpus callosum) between them
 Gazzaniga's experiment to study split brains…
o ****The information seen by the right eye is processed in the left occipital lobe, while information seen
by the left eye is processed in the right occipital lobe.
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o
split brain patient stares at a dot on a screen while the image "HE°ART" flashes on the screen.
o
o
HE appeared in the left visual field which is processed in the right hemisphere, while…
ART appeared in the right visual field which is processed in the left hemisphere
o
Patient then asked what word they had seen.. the patients said they had seen ART (because HE was
processed in the right hemisphere which isn't verbal… can't respond)
o
When asked to point to the word on a poster with their left hand (controlled by the right brain), they
pointed to HE.
o
Given the opportunity to express itself, each hemisphere reported only what is had seen. The right brain
(controlling the left hand) had not seen HE and could only report to have seen ART.
Split brains can comprehend and complete completely different tasks simultaneously.
o left brain is more active when deliberating over decisions
o right brain more active with short, quick responses and intuition, also identifies faces and facial
expressions
Studying Hemispheric Differences in the Intact Brain
 right brain – perceptual tasks
 left brain – speaking, calculating
 Lateralization – the brain’s two hemispheres are not exactly alike
o Eg: left brain largely responsible for speech (Broca’s area), if the left brain is sedated, the ability to speak
is lost, along with the ability to move the right side of the body. If the right side of the brain is sedated,
the ability to control the left side of the body is lost, along with various abilities such as the ability to
recognize one’s face in a photograph
o
Eg: People with right brain damage (stroke, etc) have difficulties recognizing subtleties in words but can
understand the meaning of the word. So presented with the words pie, belly, and luck, right brain
damaged patients can understand each word separately, but cannot see why they are related ( with the
word pot).
Brain Organization and Handedness
 ~10% of people are left-handed (more males than females)
 Research has shown that most humans (across cultures) and intelligent primates are right-handed. Also, research
into fetus development has found that 9 of 10 babies suck their right thumb in the fetus. Therefore, there is a
relationship between genes/prenatal factors and right-handedness.
A Scientific Mystery: The Case of the Disappearing Southpaws
 Researchers have found that prevalence of left-handers declines with age.
o Could it be that left-handers switch to right-handers over the lifespan?
o Decades ago, left-handedness was “corrected” in school, therefore more old people are right-handed.
Could it be that society and education are more accepting of left-handedness?
o Do left-handers die young?
 Accidents with equipment that is universally made for right-handers.
 Left-handers experience more birth stress, alcohol/tobacco use, knee-joint issues, and immune
system problems.
 These differences are huge, but early researchers concluded that right-handers live 8-9 years
longer than their counterparts. These numbers dwindle after children are excluded. Further
research has found that there is no difference in life expectancy based on handedness.