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Psychology
(9th edition)
David Myers
PowerPoint Slides
Aneeq Ahmad
Henderson State University
Worth Publishers, © 2010
The Biology of Mind
Chapter 2
The Biology of Mind
Neural Communication
 Neurons
 How Neurons Communicate
 How Neurotransmitters Influence Us
The Nervous System
 The Peripheral Nervous System
 The Central Nervous System
The Endocrine System
The Brain
• The Tools of Discovery: Having our
Head Examined
• Older Brain Structures
• The Cerebral Cortex
• Our Divided Brain
• Right-Left Differences in the Intact Brain
Neural Communication
The body’s information system is built from
billions of interconnected cells called neurons.
Neural Communication
Neurobiologists and other investigators
understand that humans and animals operate
similarly when processing information.
Note the similarities in the above brain regions, which are all
engaged in information processing.
Neuron
A nerve cell, or a neuron, consists of many
different parts.
Parts of a Neuron
Cell Body: Life support center of the neuron.
Dendrites: Branching extensions at the cell body.
Receive messages from other neurons.
Axon: Long single extension of a neuron, covered with
myelin [MY-uh-lin] sheath to insulate and speed up
messages through neurons.
Terminal Branches of axon: Branched endings of an
axon that transmit messages to other neurons.
Action Potential
A neural impulse. A brief
electrical charge that
travels down an axon and
is generated by the
movement of positively
charged atoms in and out
of channels in the axon’s
membrane.
Threshold
Threshold: Each neuron receives
excitatory and inhibitory signals from
many neurons. When the excitatory
signals minus the inhibitory signals
exceed a minimum intensity (threshold)
the neuron fires an action potential.
Action Potential Properties
All-or-None Response: A strong stimulus can
trigger more neurons to fire, and to fire more
often, but it does not affect the action potentials
strength or speed.
Intensity of an action potential remains the
same throughout the length of the axon.
Synapse
Synapse [SIN-aps] a junction between the axon
tip of the sending neuron and the dendrite or
cell body of the receiving neuron. This tiny gap
is called the synaptic gap or cleft.
Neurotransmitters
Neurotransmitters
(chemicals) released
from the sending
neuron travel across the
synapse and bind to
receptor sites on the
receiving neuron,
thereby influencing it to
generate an action
potential.
Reuptake
Neurotransmitters in
the synapse are
reabsorbed into the
sending neurons
through the process of
reuptake. This process
applies the brakes on
neurotransmitter
action.
How Neurotransmitters Influence Us
Serotonin pathways are
involved with mood
regulation.
From Mapping the Mind, Rita Carter, © 1989
University of California Press
Dopamine Pathways
Dopamine pathways
are involved with
diseases such as
schizophrenia and
Parkinson’s disease.
From Mapping the Mind, Rita Carter, © 1989
University of California Press
Neurotransmitters
Lock & Key Mechanism
Neurotransmitters bind to the receptors of the
receiving neuron in a key-lock mechanism.
Agonists
Antagonists
Nervous System
Central
Nervous
System
(CNS)
Peripheral
Nervous
System
(PNS)
The Nervous System
Nervous System: Consists of all the nerve cells. It is
the body’s speedy, electrochemical communication
system.
Central Nervous System (CNS): the brain and
spinal cord.
Peripheral Nervous System (PNS): the sensory and
motor neurons that connect the central nervous
system (CNS) to the rest of the body.
The Nervous System
Kinds of Neurons
Sensory Neurons carry incoming information from the
sense receptors to the CNS. Motor Neurons carry
outgoing information from the CNS to muscles and
glands. Interneurons connect the two neurons.
Interneuron Neuron
(Unipolar)
Sensory Neuron
(Bipolar)
Motor Neuron
(Multipolar)
Peripheral Nervous System
Somatic Nervous System: The division of the
peripheral nervous system that controls the body’s
skeletal muscles.
Autonomic Nervous System: Part of the PNS that
controls the glands and other muscles.
The Nerves
Nerves consist of neural “cables” containing many
axons. They are part of the peripheral nervous
system and connect muscles, glands, and sense
organs to the central nervous system.
Autonomic Nervous System (ANS)
Sympathetic Nervous System: Division of the
ANS that arouses the body, mobilizing its
energy in stressful situations.
Parasympathetic Nervous System: Division of
the ANS that calms the body, conserving its
energy.
Autonomic Nervous System (ANS)
Sympathetic NS
“Arouses”
(fight-or-flight)
Parasympathetic NS
“Calms”
(rest and digest)
Central Nervous System
The Brain and Neural Networks
Interconnected neurons form networks in the
brain. Theses networks are complex and modify
with growth and experience.
Complex Neural Network
Central Nervous System
The Spinal Cord and Reflexes
Simple Reflex
The Endocrine System
The Endocrine
System is the body’s
“slow” chemical
communication
system.
Communication is
carried out by
hormones
synthesized by a set
of glands.
Hormones
Hormones are chemicals synthesized by the
endocrine glands that are secreted in the
bloodstream. Hormones affect the brain and many
other tissues of the body.
For example, epinephrine (adrenaline) increases
heart rate, blood pressure, blood sugar, and
feelings of excitement during emergency
situations.
Pituitary Gland
Is called the “master gland.” The anterior pituitary
lobe releases hormones that regulate other glands.
The posterior lobe regulates water and salt
balance.
Thyroid & Parathyroid Glands
Regulate metabolic and calcium rate.
Adrenal Glands
Adrenal glands consist of the adrenal medulla and
the cortex. The medulla secretes hormones
(epinephrine and norepinephrine) during stressful
and emotional situations, while the adrenal cortex
regulates salt and carbohydrate metabolism.
Gonads
Sex glands are located in different places in men
and women. They regulate bodily development
and maintain reproductive organs in adults.
The Brain:
Older Brain Structures
The Brainstem is the oldest part of the brain, beginning
where the spinal cord swells and enters the skull. It is
responsible for automatic survival functions.
Brainstem
The Medulla [muhDUL-uh] is the base of
the brainstem that
controls heartbeat and
breathing.
Brainstem
The Thalamus [THALuh-muss] is the brain’s
sensory switchboard,
located on top of the
brainstem. It directs
messages to the sensory
areas in the cortex and
transmits replies to the
cerebellum and
medulla.
Brainstem
Reticular Formation is a
nerve network in the
brainstem that plays an
important role in
controlling arousal.
Cerebellum
The “little brain”
attached to the rear of
the brainstem. It helps
coordinate voluntary
movements and
balance.
The Brain
Techniques to Study the Brain
A brain lesion
experimentally
destroys brain tissue to
study animal behaviors
after such destruction.
Hubel (1990)
Clinical Observation
Clinical observations have shed light on a
number of brain disorders. Alterations in brain
morphology due to neurological and
psychiatric diseases are now being catalogued.
Tom Landers/ Boston Globe
Electroencephalogram (EEG)
An amplified recording of the electrical waves
sweeping across the brain’s surface, measured
by electrodes placed on the scalp.
AJ Photo/ Photo Researchers, Inc.
PET Scan
Courtesy of National Brookhaven National Laboratories
PET (positron emission
tomography) Scan is a
visual display of brain
activity that detects a
radioactive form of
glucose while the brain
performs a given task.
MRI Scan
MRI (magnetic resonance
imaging) uses magnetic
fields and radio waves to
produce computergenerated images that
distinguish among
different types of brain
tissue. Top images show
ventricular enlargement in
a schizophrenic patient.
Bottom image shows brain
regions when a
participants lies.
Both photos from Daniel Weinberger, M.D., CBDB, NIMH
James Salzano/ Salzano Photo
Lucy Reading/ Lucy Illustrations
The Limbic System
The Limbic System is a
doughnut-shaped
system of neural
structures at the border
of the brainstem and
cerebrum, associated
with emotions such as
fear, aggression and
drives for food and sex.
It includes the
hippocampus, amygdala,
and hypothalamus.
Amygdala
The Amygdala [ah-MIGdah-la] consists of two lima
bean-sized neural clusters
linked to the emotions of
fear and anger.
Hypothalamus
The Hypothalamus lies
below (hypo) the
thalamus. It directs
several maintenance
activities like eating,
drinking, body
temperature, and
control of emotions. It
helps govern the
endocrine system via
the pituitary gland.
Reward Center
Sanjiv Talwar, SUNY Downstate
Rats cross an electrified
grid for self-stimulation
when electrodes are
placed in the reward
(hypothalamus) center
(top picture). When the
limbic system is
manipulated, a rat will
navigate fields or climb
up a tree (bottom
picture).
The Cerebral Cortex
The intricate fabric of interconnected neural cells that covers
the cerebral hemispheres. It is the body’s ultimate control
and information processing center.
Structure of the Cortex
Each brain hemisphere
is divided into four
lobes that are separated
by prominent fissures.
These lobes are the
frontal lobe (forehead),
parietal lobe (top to rear
head), occipital lobe
(back head) and
temporal lobe (side of
head).
Functions of the Cortex
The Motor Cortex is the area at the rear of the
frontal lobes that control voluntary movements.
The Sensory Cortex (parietal cortex) receives
information from skin surface and sense organs.
Visual Function
The functional MRI scan
shows the visual cortex
is active as the subject
looks at faces.
Courtesy of V.P. Clark, K. Keill, J. Ma.
Maisog, S. Courtney, L.G.
Ungerleider, and J.V. Haxby,
National Institute of Mental Health
Auditory Function
The functional MRI scan
shows the auditory
cortex is active in
patients who hallucinate.
Association Areas
More intelligent animals have increased
“uncommitted” or association areas of the
cortex.
Language
Aphasia is an impairment of language, usually
caused by left hemisphere damage either to Broca’s
area (impaired speaking) or to Wernicke’s area
(impaired understanding).
Specialization & Integration
Brain activity when hearing, seeing, and
speaking words
The Brain’s Plasticity
The brain is sculpted by our genes but also by our
experiences.
Plasticity refers to the brain’s ability to modify
itself after some types of injury or illness.
Our Divided Brain
Our brain is divided into two hemispheres.
The left hemisphere processes reading, writing,
speaking, mathematics, and comprehension
skills. In the 1960s, it was termed as the
dominant brain.
Splitting the Brain
A procedure in which the two hemispheres of the
brain are isolated by cutting the connecting fibers
(mainly those of the corpus callosum) between them.
Martin M. Rother
Courtesy of Terence Williams, University of Iowa
Corpus Callosum
Split Brain Patients
With the corpus callosum severed, objects (apple)
presented in the right visual field can be named.
Objects (pencil) in the left visual field cannot.
Divided Consciousness
Try This!
Try drawing one shape with your left hand and
one with your right hand, simultaneously.
BBC
Right-Left Differences in the Intact
Brain
People with intact brains also show left-right
hemispheric differences in mental abilities.
A number of brain scan studies show normal
individuals engage their right brain when
completing a perceptual task and their left brain
when carrying out a linguistic task.
Evolution
• Charles Darwin: The Man.
– The HMS Beagle voyage.
– Cousin of Sir Francis Galton.
– Influenced by Thomas Malthus’s “Essay of
the Principle of Population”.
– Presented “On the Origin of the Species
by Natural Selection” in 1859.
• Book sold out in the first day.
Figure 2.1 Humans and Some “Relatives.” The idea that humans were
genetically related to apes and other animals was so distant from 19thcentury views of the species that Darwin was initially reluctant to disclose
his theory of evolution. The Descent of Man, published in 1871, made the
case that humans, like other species, were a product of evolution. Darwin
believed that the great apes (chimpanzees, gorillas, and so on) and
humans shared a common primate ancestor.
Evolution and Evolutionary Psychology
•
•
Theory of Evolution.
– Natural Selection:
• Survival of the fittest.
– Biology serves as the material base for our behaviors, emotions and
cognitions.
– Mutations:
– differences in individual traits and/or adaptations for survival
Evolutionary Psychology:
– Applying adaptation and natural selection to mental processes and
behavior.
– Instincts:
• stereotyped pattern of behavior that is triggered in specific
situations
– Examples of instincts: The Egg Zone; Stickleback Fish; Song
of the Sparrow.
Heredity
• one’s biological structures and
processes transmitted from generation
to generation.
• Behavioral Genetics:
– Bridges the sciences of psychology and
biology. Concerned with the genetic
transmission of traits that give rise to
patterns of behaviors.
Figure 2.2 The Double Helix of DNA. Segments of DNA are made up of genes that determine physical traits
such as height, eye color, and whether pigs have wings (no, because of their genetic makeup, they don’t.) The
overlap of DNA from person to person is 99.9%! Yet the difference in .1% accounts for the differences between
Mozart, and Nelson Mandela, and between Michelle Kwan and Oprah Winfrey. Psychologists debate the extent
to which genes influence psychological traits such as intelligence, aggressiveness, and happiness, and the
appearance of psychological disorders such as schizophrenia.
Heredity: The Nature of Nature
• Molecular Genetics:
– attempts to identify specific genes that are
connected with behavior and mental
processes.
• Examples include:
–
sociability, shyness, aggressiveness, thrill seeking,
anxiety, depression, schizophrenia, bipolar
disorder, alcoholism, and criminal behavior.
Heredity: The Nature of Nature
•
•
•
Genes:
– basic building blocks of heredity. 30,000 - 40,000 genes
within every cell of a person’s body.
Chromosomes:
– strings of genes. Each cell contains 46 arranged in 23
pairs.
DNA:
– Chromosomes are large complex molecules of
deoxyribonucleic acid (DNA).
Heredity: The Nature of Nature
Human Genome Project:
•
has learned that the sequencing of your DNA consists of about 3
billion DNA sequences.
•
Genetic Code:
– The DNA sequences that “define” each person.
– Sperm and Egg:
•
23 chromosomes from the father’s sperm and 23
chromosomes from the mother’s egg. When the egg is
fertilized by the sperm they form 23 pairs.
– Sex Chromosomes:
•
The 23rd pair of chromosomes which determine a person’s
sex, male or female. X female; Y male.
•
Determined by father.
Figure 2.3 The 23 Pairs of Human Chromosomes. People normally have 23 pairs of chromosomes. Whether one is
female or male is determined by the 23rd pair of chromosomes. Females have two X sex chromosomes, whereas
males have an X and a Y sex chromosome.
Kinship Studies
• Attempt to compare traits and behavior
patterns in people who are biologically
related or unrelated to help determine the
role of genetic factors.
• Twin Studies
– Monozygotic Twins (MZ):
•
Identical twins from the same fertilized egg.
– Dizygotic Twins (DZ):
•
Fraternal twins, two separate fertilized eggs.
– Twin studies compare the presence of traits in
MZ twins, DZ twins and others to help determine
the role of genetic factors.
•
If MZ twins show greater similarity on a trait than DZ
twins a genetic basis for the trait has been suggested.
Adoption Studies
• Look for similarities between children, their
natural and adoptive parents.
• When children reared by adoptive parents are more
similar to their natural parents in a particular trait, strong
evidence exists for a genetic role.
Selective Breeding
• Enhances desired physical and
behavioral traits.
– Examples: cattle, chicken, dogs.
– Tryon rat studies: Bred rats to become
“maze dull” and “maze bright”.
•
By the seventh generation maze bright rats
are making only one error per trial, maze dull
are making 9-10 errors per trial.
Figure 2.4 Selective Breeding for Maze-Learning Ability in Rats. Humans selectively breed animals and plants to
achieve desired physical traits. However, in the case of animals, it is also possible to selectively breed for
psychological traits and behaviors such as aggressiveness and trainability (in dogs) and maze learning ability (in
rats). In the classic Tryon (1940) study, “maze bright” and “maze-dull” rats were selectively bred over generations,
until the distributions of their maze-learning ability barely overlapped.
The Nervous System
• Neurons: the nerve cells of the body
– Cell Body:
•
contains the nucleus which generates energy
– Dendrites:
•
receive incoming messages from adjourning
cells (roots).
– Axon:
•
carry messages away from the cell body
(trunk).
Figure 2.5 The anatomy of a neuron. Message enter neurons through dendrites, are transmitted along the trunklike
axon, and are then sent from the axon terminal buttons to muscles, glands and other neurons. Axon terminal buttons
contain sacs of chemicals called neurotransmitters. Neurotransmitters are released into the synaptic cleft, where
many of them bind to receptor sites on the dendrite of the receiving neuron. Dozens of neurotransmitters have been
identified.
The Nervous System
• Parts of a neuron continued.
– Terminals (terminal buttons):
•
bulb shaped structure at the end of the axon.
– Myelin:
•
fatty substance around axons that facilitate
conduction.
– Glial cells:
•
remove dead neurons and waste products
from the nervous system.
The Neural Impulse
•
•
A message traveling along the neuron; between 2 and 225
miles an hour.
An Electrochemical Voyage.
– Neuron resting potential:
• -70 millivolts (negative charge).
– Depolarized:
• action of the cell while it becomes positively charged.
– Action potential:
• positively charged neuron returning to the resting state
of being negatively charged. The “message” is sent.
Figure 2.6 When a section of a neuron is stimulated by other neurons, the cell membrane becomes permeable to
sodium ions so that an action potential of about 40 millivolts is induced. This action potential is transmitted along the
axon. The neuron fires according to the all-or-none principle.
Firing
• neurons attempt to transmit messages to
other neurons, muscles or glands.
– Threshold:
•
Each neuron has a threshold; the cell will not fire until
the threshold is reached.
– All or None Principle:
•
When the threshold is reached the neuron fires an
impulse of the same strength.
– Refractory Period:
•
a period of time when the neuron will not fire; period of
recovery during which positive sodium is not allowed to
pass through the neural membrane.
– Synapse:
•
Junction (fluid filled gap between neurons).
Neurotransmitters: The Chemical Keys
to Communication
• Synaptic Vesicles:
– sacs in the axon terminals which contain
neurotransmitters.
• Neurotransmitters:
– the chemical keys to communication which
influence the receiving neuron
– Receptor Site:
•
specifically tailored site on the receiving neuron where
the chemical key (neurotransmitter) fits.
– Reuptake:
•
reabsorption of neurotransmitters by the sending
neuron.
– Excitatory:
•
neurotransmitter influence on the receiving cell causing
it to fire.
– Inhibitory:
Types of Neurotransmitters
•
•
Acetylcholine (ACh):
– controls muscle contractions; can be both excitatory and
inhibitory.
– Curare and Botulism both leading to paralysis.
– Decreases in ACh is associated with Alzheimer's related
memory problems.
Dopamine:
– affects voluntary movements, learning, memory and
arousal.
– Deficiencies are linked to Parkinson’s Disease.
– People with schizophrenia may have more receptor sites
for dopamine leading to confusion and false perceptions.
Types of Neurotransmitters
• Norepinephrine:
– produced largely in the brain stem; acts as
a neurotransmitter and as a hormone;
– involved in general arousal, learning and
memory, and eating; linked to mood
disorders.
– Cocaine creates an excess of
norepinephrine leading to persistent
arousal.
• Serotonin:
– involved in emotional arousal and sleep.
– Deficiencies have been linked to eating
Types of Neurotransmitters
•
•
Gamma-aminobutyric acid (GABA):
– inhibitory neurotransmitter that may help calm anxiety
reactions.
– Tranquilizers and alcohol may quell anxiety by binding with
GABA receptors.
Endorphins:
– inhibitory neurotransmitter; endogenous morphine.
– Natural painkiller.
– Experienced by runners as the runner’s high.
The Parts of the Nervous System
• Nerve:
– a bundle of axons.
• Central Nervous System:
– brain and spinal cord.
• Peripheral Nervous System:
– afferent and efferent neurons which
transmit messages from the brain or
spinal cord to muscles and glands.
Figure 2.8 The Divisions of the Nervous System. The nervous system contains two main divisions: the central
nervous system and the peripheral nervous system. The central nervous system consists of the brain and spinal
cord. The peripheral nervous system contains the somatic and autonomic systems. In turn, the autonomic nervous
system has sympathetic and parasympathetic divisions.
The Peripheral Nervous System
• Somatic Nervous System:
– afferent and efferent neurons that transmit
sights, sounds, smells, temperature, body
positions, etc.
– Purposeful body movements.
• Autonomic Nervous System:
– “Automatic” regulates the glands and
internal organ muscles; heartbeat,
respiration, digestion, dilation of the
pupils, etc.
•
Sympathetic Division:
–
active during processes that involve spending body
Figure 2.9 The Branches of the Autonomic Nervous System. The parasympathetic branch of the ANS generally
acts to replenish stores of energy in the body. The sympathetic branch is the most active during activities that expend
energy. The two branches of the ANS frequently have antagonistic effects on the organs they service.
The Central Nervous System
• Spinal Cord: column of nerves
transmits messages from sensory
receptors to the brain and from the
brain to muscles and glands throughout
the body
– Spinal Reflexes: unlearned response to a
stimulus that may involve only two
neurons: afferent and efferent.
– Interneuron: a third neuron that transmits
the neural impulse from the sensory
neuron through the spinal cord to the
The Brain: The Star of the Nervous
System
• Gender Differences
– Size
• Men 15% larger (related to body size
difference)
– How well connected
• Women metabolize more glucose and use
more of their brains
Seeing the Brain Through the Eyes of
the Psychologist
• Accidents.
– provide unplanned, uncontrolled
opportunities of studying the brain (see
Phineas Gage).
• Experimenting with the Brain.
– Lesioning: damaging part of the brain.
• The Electroencephalograph (EEG).
– EEG detects minute amounts of electrical
activity in the brain.
• Brain Imaging Techniques.
CAT (computerized axial tomograph)
• A scan which passes a narrow X-ray
beam through the head and measures
brain structures.
• Generates a three dimensional image
of the brain.
• Reveals deformities in shape and
structure that are connected with blood
clots, tumors, and other health
problems.
MRI (magnetic reasoning imaging)
• Person lies in a powerful magnetic field
and is exposed to radio waves that
cause parts of the brain to emit signals.
• Relies on subtle shifts in blood flow.
• MRI has shown people with
schizophrenia have smaller prefrontal
regions but larger ventricles.
PET (positron emission tomography)
•
•
•
computer generated image of the activity of parts of the brain
by tracing the amount of glucose used.
A harmless amount of radioactive compound (tracer) is mixed
with glucose and injected into the blood stream.
Used to see which parts of the brain are most active when we
are engaged in various activities
– Examples include:
• listening to music,
• working out, and
• math problems
Voyage Through the Brain
•
Hindbrain: where the spinal cord meets the brain. Contains
three structures.
– Medulla:
• regulates vital functions such as heart rate, blood
pressure, and respiration.
– Pons:
• transmits information about body movements and is
involved in functions related to attention,
sleep/alertness and respiration.
– Cerebellum:
• involved in maintaining balance and controlling motor
behavior.
Figure 2.13 The Parts of the Human Brain. This view of the brain, split top to bottom, shows some of the most
important structures. Note how close the hypothalamus is to the pituitary gland. The proximity allows the
hypothalamus to readily influence the pituitary gland. The “valleys” in the cerebrum are called fissures.
Voyage Through the Brain
• Reticular Activating System (RAS):
– vital in the functions of attention, sleep
and arousal.
Forebrain
•
•
•
forward most part of the brain containing thalamus,
hypothalamus, limbic system and the cerebrum.
Thalamus:
– relay station for sensory stimulation.
Hypothalamus:
– vital for body temperature regulation, concentration of
fluids, storage of nutrients, aspects of motivation and
emotion.
– Also involved in hunger, thirst and sexual behavior.
Forebrain
• Limbic System:
– Includes the amygdala, hippocampus, and parts
of the hypothalamus.
– Involved in memory, emotion and in the drives of
hunger, sex and aggression.
– Amygdala:
•
connected with aggression, fear response, and
vigilance.
• Cerebrum:
– responsible for thinking and language.
Figure 2.14 The Limbic System. The limbic system is made up of structures that include the amygdala, the
hippocampus, and parts of the hypothalamus. It is evolved fully only in mammals and forms a fringe along the inner
edge of the cerebrum. The limbic system is involved in memory and emotion, and in the drives of hunger, sex, and
aggression
Corpus Callosum
• a bundle of some 200 million nerve
fibers connecting the two hemispheres.
Figure 2.15 The Geography of the Cerebral Cortex. The cortex is divided into 4 lobes: frontal, parietal, temporal,
and occipital. The visual area of the cortex is located in the occipital lobe. The hearing or auditory cortex lies in the
temporal lobe. The sensory and motor areas face each other across the central fissure.
Language Functions
•
Aphasia: disruption in the ability to understand or produce
language.
– Wernicke’s Area:
• in the temporal lobe responds mainly to auditory
information.
– Wernicke’s aphasia:
– impaired ability to comprehend speech and to think
of the proper words to express.
– Broca’s area:
• processes information and sends it to the motor cortex.
– Broca’s aphasia:
• Damage to this area results; people can understand
language but will speak slowly in simple sentences.
Figure 2.16 Broca’s and Wernicke’s Areas of the Cerebral Cortex. The areas that are most involved in speech
are Broca’s area and Wernicke’s Areas of the Cerebral Cortex. Damage to either area can produce an aphasia--a
disruptions o the ability to understand or produce language.
Left Brain, Right Brain
• Left Brain, Right Brain.
– Left brain:
•
primarily logical and intellectual.
– Right brain:
•
primarily intuitive, creative, and emotional.
• At best this is exaggerated.
• The hemispheres do not act
independently as they are connected
by the corpus callosum.
Handedness
• Is It Gauche or Sinister to Be Left
Handed?
– Lefties: 8-10% of people are left handed;
more common in males.
•
•
Has been connected with language problems,
dyslexia, stuttering, migraine headaches,
allergies, schizophrenia.
On the other side being left handed is
associated with artists, musicians, and
mathematicians.
– Handedness runs in families.
Split Brain Experiments
• Some people with epilepsy have split
brain operations in which much of their
corpus callosum is severed.
• Each hemisphere has a mind of it’s
own.
– One patient described a situation he
encountered, as one hemisphere liking
reading and other not.
– If he shifted the book from his right hand
to his left, his left hand would put the book
down.
Figure 2.18 A Divided-Brain Experiment. In the drawing on the left, we see that visual sensations in the left visual
field are projected in the occipital cortex of the right hemispheres. Visual sensations from the right visual field are
projected in the occipital cortex in the left hemisphere. In the divided-brain experiment diagrammed on the right, a
person with a severed corpus callosum handles a key with his left hand and perceives the written word key in his left
visual field. The word ‘key” is projected in the right hemisphere. Speech, however is usually a function of the left
hemisphere. The written word “ring” perceived by the right visual field is projected in the left hemisphere. So when
asked what he is handling, the divided-brain subject reports “ring,” not “key.”
The Endocrine System: Chemicals in the
Bloodstream
• Glands: secrete hormones.
– Two types:
• With ducts (saliva, sweat, tears).
• Without ducts (released into the blood stream).
• Pituitary Gland:
– implicated in growth.
– sometimes referred to as the Master Gland
as it influences other glands in the
endocrine system.
Types of Hormones
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Growth Hormone:
– regulates growth of muscles, bones and glands.
Prolactin:
– regulates maternal behavior in lower animals such as rats, also
produces milk in women.
Antidiuretic Hormone (ADH):
– inhibits production of urine when fluid levels in the body are low.
Oxytocin:
– stimulates labor in pregnant women.
Melatonin:
– secreted by the Pineal gland and helps regulate the sleep-wake
cycle.
Types of Hormones
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Thyroxin:
– secreted by the thyroid and affects the body’s metabolism.
• Hypothyroidism is too little thyroxin and results in being
overweight.
• Hyperthyroidism is too much thyroxin and is characterized by
excitability, insomnia, and weight loss.
• Cretinism is a conditioned caused by a deficiency in thyroxin in
children which leads to stunted growth and mental retardation.
Adrenal glands:
– release hormones to increase resistance to stress.
– Promote muscle development and the release of sugar in the liver
making more energy available.
– Epinephrine: is also known as adrenaline; produced by the adrenal
glands.
Types of Hormones
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Testosterone: produced by the testes and in small amounts by the
ovaries.
– Considered to be the male sex hormone as it aids in the
development of male sex organs.
– During puberty the release of testosterone promotes the
development of primary and secondary sex characteristics.
– Primary sex characteristics:
• those characteristics involved in reproduction: increased penis
size, sperm producing ability of the testes.
– Secondary sex characteristics:
• Not directly related to reproduction: presence of a beard,
deeper voice.
Estrogen and Progesterone: produced by the ovaries and in small
amounts by the testes.
– Fosters female reproductive capacity and secondary sex
characteristics.
– The levels of estrogen and progesterone vary and regulate the
woman’s menstrual cycle.
Steroids, Behavior and Mental
Processes
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Anabolic (synthetic) steroids are used with growth hormone to enhance
– Athletic prowess
– Self-confidence
– Aggressiveness
– Memory functioning
Linked liver damage and other health problems
Estrogen affects women’s perceptions of who is attractive
– Prefer feminized mail faces during most phases of menstrual cycle
Premenstrual Syndrome (PMS)
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3 out of 4 women report having some psychological and physical
problems
– Depression, anxiety, and headaches during the four to six days that
precede menstruation.
However only 1 in 10 has symptoms severe enough to impair
academic, occupational, or social functioning.
PMS may be a complex interaction between ovarian hormones and
neurotransmitters.
Once seen as something a woman must tolerate, today there are many
treatment options (diet, exercise, hormone treatments).