Neuroscience




Parts of a neuron
Action potential
Major neurotransmitters
Agonists/Antagonists
Neural and Hormonal Systems
Neurons are to the nervous system as
hormones are to the endocrine system
Nervous System- fast response and quick to
leave
Endocrine System-slower response and stay in
your body longer
History of the Mind
Phrenology
Bettman/ Corbis
In 1800, Franz Gall
suggested, that bumps of
the skull represented
mental abilities. His theory
though incorrect,
nevertheless proposed
different mental abilities
were modular.
Neural Communication
The body’s information system is built from billions of
interconnected cells called neurons.
Neural Communication
Neurobiologists and other investigators understand
that information processing in humans and animals
operate similarly.
Note similarity of brain regions involved with
information processing of similar kind.
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. Receives
messages from other neurons.
Axon: Long single extension of a neuron, covered with
myelin sheath to insulate and speed up messages through
neurons.
Terminals of axon (terminal buttons): Branched ending of
axons. Transmit neurotransmitters to other neurons.
Action Potential
A neural impulse. A brief electrical charge that travels
down an axon generated by the movement of positively
charged atoms in and out of channels in the axon’s
membrane.
Depolarization & Hyperpolarization
Depolarization: Depolarization occurs, when
positive ions enter the neuron, making it more
susceptible to fire an action potential. When
negative ions enter the neuron making it less
susceptible to fire, hyperpolarization occurs.
Threshold
Threshold: Each neuron receives depolarizing and
hyperpolarizing currents from many neurons. When
the depolarizing current (positive ions) minus the
hyperpolarizing current (negative ions) exceed
minimum intensity (threshold) the neuron fires an
action potential.
Refractory Period & Pumps
Refractory Period: After a neuron has fired an
action potential it pauses for a short period to
recharge itself to fire again.
Sodium-Potassium Pumps: Sodium-potassium
pumps pump positive ions out from the inside of
the neuron, making them ready for another action
potential.
Action Potential Properties
All-or-None Response: When depolarizing current
exceeds the threshold a neuron will fire, and below
threshold it will not.
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.
May be “excitatory” or
“inhibitory”
Reuptake
Neurotransmitters in the
synapse are reabsorbed into the
sending neurons through the
process of reuptake. Don’t
move on to the next neuron.
For example:
People who suffer from
depression have lower levels of
serotonin. They may take an
SSRI which blocks reuptake
(thus flooding the synapse with
more serotonin)
How Neurotransmitters Influence Us
Serotonin pathways are
involved with mood
regulation (depression).
From Mapping the Mind, Rita Carter, © 1989
University of California Press
Dopamine Pathways
Dopamine pathways
are involved with
diseases like
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




Nervous system
Afferent/Efferent neurons
Parts of the autonomic nervous system
Endocrine system
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 (afferent) carry incoming information
from the sense receptors to the CNS. Motor Neurons
(efferent) carry outgoing information from the CNS to
muscles and glands. Interneurons connect the two neurons.
Sensory Neuron
(Bipolar)
Interneuron Neuron
(Unipolar)
Motor Neuron
(Multipolar)
Kinds of Glial Cells
Glial cells function as
support cells , hold
together message
sending neurons and
support their functioning.
Kind of like “glue”
Example: Schwann cells
insulate neurons as
myelin.
Peripheral Nervous System
Somatic Nervous System: The division of the peripheral
nervous system that controls the body’s skeletal
muscles. You have “some” control of this.
Autonomic Nervous System: Part of the PNS that
controls the glands and other muscles. Functions
automatically.
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. Gets you ready for fight or
flight.
Parasympathetic Nervous System: division of the
ANS that calms the body, conserving its
energy. Brings you back down after the
threat is over.
Autonomic Nervous System (ANS)
Sympathetic NS
“Arouses”
(fight-or-flight)
Parasympathetic NS
“Calms”
(rest and digest)
The Endocrine System
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 and secreted in the bloodstream. Hormones
affect the brain and many other tissues of the body.
Hormones remain in your system longer than
neurotransmitters.
For example, epinephrine (adrenaline) increases heart
rate, blood pressure, blood sugar and feelings of
excitement during emergency situations. After the
situation has passed, you may continue to tremble.
Pituitary Gland
Is called the “master gland.” Anterior pituitary lobe
releases hormones that regulate other glands.
Posterior lobe regulates water and salt balance.
Pineal gland
• Located near the center of the brain between
the two hemispheres, shaped like a pine cone
• Secretes the hormone melatonin which
influences our sleep/wake cycle
• Connects the endocrine
system with the nervous
system (allows them to
communicate)
Thyroid & Parathyroid Glands
Regulate metabolic and calcium rate.
Adrenal Glands and Pancreas
Adrenal glands consists of adrenal medulla and cortex.
Medulla secretes hormones (epinephrine and
norepinephrine) during stress and emotions, and adrenal
cortex regulates salt and carbohydrate metabolism.
The pancreas regulates the level of sugar in the blood
by producing insulin. It also plays a role in the digestive
system
Gonads
Sex glands are differentially placed in men and
women. Regulate bodily development and maintain
reproductive organs in adults.
AP Test info…
• Know the order of an action potential fire
• Afferent (sensory) vs Efferent (motor)
neurons
• Sympathetic vs parasympathetic
• Destruction of the myelin sheath causes…
• Low AcH causes…
Neuron Review
• What are the 3 main structures of all Neurons?
• What does myelin do?
• What is the impact of alcohol on the brain?
Ecstasy?
• How are axons and Dendrites different?
• Afferent neurons (sensory)– Send information from
the body to the brain
• Efferent neurons (motor)– Send information from
the brain to the body.
Neurotransmitter Review
• Low levels of this neurotransmitter may result in
depression and suicide.
Serotonin
• Excess amounts of this neurotransmitter may result in
Schizophrenia
Dopamine
• Due to it also being a hormone, this
neurotransmitter is also known as noradrenaline.
Norepinephrine
• Low levels of this neurotransmitter may be
responsible for Alzheimer’s Disease.
Acetylcholine (Ach)
Neurotransmitter Review
• Low levels of this neurotransmitter leads to Parkinson’s
disease. High levels???
Dopamine
• This neurotransmitter is used during muscle contraction.
Acetylcholine
• What is the major inhibitory neurotransmitter?
GABA
• Lower levels of this neurotransmitter are generally found in
women.
Serotonin
The Brain



Methods to study the brain
Old Brain (all parts with a description)
Limbic system (all parts with description)
The Brain
Techniques to Study the Brain
Brain lesion
experimentally destroys
brain tissue to study
animal behaviors after
such destruction.
Hubel (1990)
Phineas Gage
• He was a railway worker who was
severely injured when a 13 pound
metal rod was driven through his
skull in an explosion
• He recovered, but the damage to
the front lobes and the severing of
the connective tissue to the limbic
system left him a changed person
• Scientists have learned much about
the functioning and specialization of
different areas of the brain
Electroencephalogram (EEG)
An amplified recording of the electrical waves
sweeping across the brain’s surface, measured by
electrodes placed on the scalp. (shows functioning)
AJ Photo/ Photo Researchers, Inc.
The CAT Scan
Computerized Axial Tomography
• CAT scans use a series of Xray beams passed through
the head. The images are
then developed on sensitive
film. This method creates
cross-sectional images of the
brain and shows the structure
of the brain, but not its
function.
(shows structure)
PET Scan
Courtesy of National Brookhaven National Laboratories
PET (positron emission
tomography) Scan a visual
display of brain activity
that detects a radioactive
form of glucose while the
brain performs a given task.
(shows function)
MRI Scan
MRI (magnetic resonance
imaging) uses magnetic fields
and radio waves to produce
computer-generated images
that distinguish among
different types of brain tissue
(shows structure)
fMRI produces images while
performing a task (reciting
alphabet)
**(shows structure and
function)**
Both photos from Daniel Weinberger, M.D., CBDB, NIMH
Reptilian “Old” Brain Structures
Brainstem the oldest part of the brain, beginning
where the spinal cord swells and enters the skull.
Responsible for automatic survival functions.
Brain Stem
Medulla [muh-DUL-uh]
base of the brainstem,
controls heartbeat and
breathing.
Reticular Formation a
nerve network in the
brainstem that plays an
important role in
controlling arousal.
Brain Stem
Thalamus [THAL-uh-muss] 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.
Basal Ganglia
Pons functions as a bridge
between regions and plays a role
in sleep and arousal
Pons
Cerebellum
The “little brain” attached
to the rear of the brainstem.
It helps coordinate
voluntary movements and
balance. It also plays a role
in the formation of
procedural memories
(implicit or procedural
memories,
EX. riding a bike)
The Limbic System
Limbic System 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 and the ,
amygdalae.
Amygdala
Amygdala [ah-MIG-dahla] two almond-shaped
neural clusters linked to
emotion of fear and
anger.
Hippocampus
• The hippocampus is a
structure in the limbic
system which is
responsible for the
formation of most new
memories (explicit
memories, EX. facts)
Hippocampus
Hypothalamus
Hypothalamus lies below
(hypo) the thalamus;
directs several
maintenance activities
like eating, drinking, body
temperature, and
emotions. Helps govern
the endocrine system via
the pituitary gland.
New Brain
 New Brain (cortex)
 The four lobes and their
functions
 Language features of the brain
 Split brain procedure
The Cerebrum
• Cerebrum –
Topmost layer of the brain; the bulbous
cap over the limbic system
• Cerebral cortex –
Thin gray-matter covering of the
cerebrum; carries on thinking and
perceiving
• Cerebral hemispheres –
The two walnut shaped halves of the
cerebrum, connected by the corpus
callosum
Copyright © Allyn & Bacon 2007
The Cerebral Cortex
The intricate fabric of interconnected neural cells that covers the
cerebral hemispheres. The body’s ultimate control and
information processing center.
Structure of the Cortex (New Brain)
Each brain hemisphere is
divided into four lobes,
separated by prominent
fissures. They are frontal
lobes (forehead), parietal
lobes (top to rear head),
occipital lobes (back
head) and temporal lobes
(side of head).
The 4 Lobes
Frontal Lobe
• Concerned with
reasoning, planning,
parts of speech and
movement (motor
cortex), emotions,
and problem-solving.
The Temporal Lobe
• Concerned with
perception and
recognition of
auditory stimuli
(hearing) and
memory
(hippocampus).
The Occipital Lobe
• Located at the back
of the brain, behind
the parietal lobe and
temporal lobe.
• Concerned with
many aspects of
vision.
The Parietal Lobe
Concerned with
perception of stimuli
related to touch,
pressure,
temperature and
pain.
Functions of the Cortex
Motor Cortex area at the rear of the frontal lobes
controls voluntary movements. Sensory Cortex
(parietal cortex) receives information from skin
surface and sense organs.
Visual Function
Courtesy of V.P. Clark, K. Keill, J. Ma.
Maisog, S. Courtney, L.G.
Ungerleider, and J.V. Haxby,
National Institute of Mental Health
Functional MRI scan
shows the visual cortex
activates as the subject
looks at faces.
Auditory Function
Functional MRI scan shows
the auditory cortex is
activate 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
Brain is sculpted by our genes but also by our
experiences.
Plasticity refers to the brain’s ability to modify itself
after some type of injury or illness.
When we are young our brains are more plastic.
Our Divided Brain
Our brain is divided into two hemispheres.
Left hemisphere processes reading, writing, speaking,
mathematical, comprehension skills, and thus termed as
the dominant brain in the 1960s.
Splitting the Brain
A form of psychosurgery in which the two hemispheres of
the brain are isolated by cutting the connecting fibers
(mainly those of the corpus callosum) between them.
Roger Sperry conducted research on this procedure to
help people suffering from grand mal seizures
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.
This is “Split Brain Joe”,
that is not Michael Gazzaniga
with him
BBC
78
Brain Organization & Handedness
Is handedness inherited? Yes. Archival and historic
studies to modern medical studies point that right
hand is preferred. This suggests, genes and/or
prenatal factors influence handedness.
The latest research…
AP Exam stuff…
-What about the forebrain, midbrain, hindbrain?
forebrain-cerebrum, thalamus, and hypothalamus
midbrain-Limbic system
hindbrain-medulla, cerebellum, pons
***Often the midbrain, pons, and medulla are
referred to together as the brainstem***
-Know the parts and their functions
-Understand the different scans, what they
show
-Why and how to do a split brain operation?
Lobes of the Brain (Review)
• What are the four lobes of the human brain?
Frontal, Temporal, Occipital, Parietal
• Which is important for active through and controlling
impulsive behavior?
Frontal
• Which one is responsible for your sense of hearing?
Temporal
• Which one is responsible for your sense of vision?
Occipital
• Which one is responsible for your sense of pressure,
temperature, and pain?
Parietal
Brain structure Review
• Connects the left and right hemisphere
Corpus Callosum
• Most of our brain is composed of this structure.
Cerebrum
• The outer ¼ inch of the cerebrum
Cortex
• Heartbeat, respiration, blood pressure
Medulla
• Balance and Coordination
Cerebellum
• Relay station for sensory information
Thalamus
Essay themes
• How neurotransmitters and hormones affect
behavior
• Basic functions of the structures of the brain
Behavior Genetics and
Evolutionary
Psychology
Module 6
88
Nature, Nurture and Human Diversity
Similarities
Differences
Genes: Same set of
chromosomes
Genes: Genetic anomalies
may make us different
Biology: The organs and
body function the same
Biology: May change
during development
Brain: Same brain
architecture
Brain: Asymmetry of brain
across genders
Behaviors: Speak language
Behavior: Speak different
languages
89
Behavior Genetics: Predicting Individual
Differences
Behavior Geneticists study our differences and
weigh the relative effects of heredity and
environment.
90
Genome
Genome is the set of complete instructions for
making an organism Containing all the genes in
that organism. Thus human genome makes us
human and the genome for drosophila makes it a
common house fly.
91
Twin Biology
To study the effects of heredity and
environment two sets of twins, identical and
fraternal, have come in handy.
92
Twin and Procedures
Behavior geneticists study the effects of shared
and unique environments on total or partial
genetic makeup.
93
Separated Twins
A number of studies have looked at identical
twins raised separately from birth or close there
after and have found a number of similarities.
Separated Twins
Personality, Intelligence
Abilities, Attitudes
Interests, Fears
Brain Waves, Heart Rate
94
Adoptive Studies
Adoptive studies strongly point to the simple
fact that biologically related children turn out to
be different in a family. So investigators ask:
Do siblings have differing experiences?
Do siblings, despite sharing half of their genes, have
different combinations of the other half genes?
Ultimate question: Does parenting have an effect?
95
Parenting
Parenting does have an effect on biologically
related and unrelated children.
Parenting Influences
children’s
Attitudes, Values
Manners, Beliefs
Faith, Politics
96
Temperament Studies
Temperament refers to a person’s stable
emotional reactivity and intensity. Identical
twins express similar temperaments, suggesting
heredity predisposes temperament.
97
Heritability
Heritability refers to the extent to which the
differences among people are attributable to genes.
98
Group Differences
If genetic influences help explain individual
diversity in traits, can the same be said about
group differences?
Not necessarily. Individual differences in
weight and height are heritable and yet
nutritional influences have made westerners
heavier and taller than their ancestors a century
ago.
99
Nature and Nurture
Some human traits are fixed, like having two
eyes, most psychological traits are liable to
change with environmental experience.
So genes provide choices to the organism to
change its form or traits when environmental
variables change. Therefore genes are pliable or
self-regulating.
100
Gene-Environment Interaction
Genes can influence traits which affect
responses, and environment can affect gene
activity.
A genetic predisposition that makes a child
restless and hyperactive, evokes angry
responses from his parents. A stressful
environment can trigger genes to manufacture
neurotransmitters leading to depression.
101
Evolutionary Psychology: Understanding
Human Nature
Molecular genetics studies why we as
organisms are distinct.
Evolutionary psychology studies why we as
humans are alike. In particular it studies the
evolution of behavior and mind using
principles of natural selection.
102
Natural Selection
Natural selection is an evolutionary process
through which adaptive traits are passed on to
ongoing generations because they lead animals
to reproduce and survive.
103
Human Traits
A number of human traits have been identified
as a result of pressures afforded by natural
selection.
Why do infants fear strangers when they become
mobile?
Why are most parents so passionately devoted to their
children?
Why do people fear spiders and snakes and not
electricity and guns?
104
Mating Preferences
In order for males to pass their genes into future
they look for youthful appearance in females.
Females on the other hand look for maturity,
dominance, affluence and boldness in males.
Data based on 37 cultures.
105
Environmental
Influences on Behavior
Module 7
106
Experience and Brain Development
Early postnatal experience affects brain
development. Rosenzweig et al. (1984) showed
that rats raised in enriched environments
developed thicker cortices than those in
impoverished environment.
107
Experience and Faculties
Early experience during development in
humans have also shown remarkable
improvements in music, languages and the arts.
Courtesy of C. Brune
108
Brain Development and Adulthood
Brain development does not stop with
adulthood. Throughout our life brain tissue
continues to grow and change.
Both hotos courtesy of Avi Kani and Leslie
Ungerleider, National Institue of Mental Health
A well-learned finger tapping task leads to
more motor cortical neurons (right) than baseline.
109
Variation Across Culture
Cultures differ. Each culture develops norms –
rules for accepted and expected behavior. Men
holding hands in Arabia is normal (closer
personal space) not in American culture.
Jason Reed/ Reuters/Corbis
110
Variation Over Time
Cultures change over time. Rate of this change
can be extremely fast. This has happened in
many countries in the West where culture has
rapidly changed over past 40 years or so.
This change cannot be attributed to changes in
the human gene pool because genes evolve very
slowly.
111
Culture and the Self
If cultures nurture an
individual’s personal
identity they give rise to
individualism, but if
group identity is favored
then culture marks
collectivism.
Kyodo News
Collectivist support system
can help group in disaster like
earthquake in 2005 in
Pakistan.
112
Culture and the Self
113
Culture and Child-Rearing
Individualist cultures (European) raise their
children as independent individuals whereas
collectivist cultures (Asian) rears their children
as interdependent.
Jose Luis Palaez, Inc./ Corbis
114
Culture and Child-Rearing
Westernized Cultures
Asian-African Cultures
Responsible for your self
Responsible to group
Follow your conscience
Priority to obedience
Discover your gifts
Be true to family-self
Be true to yourself
Be loyal to your group
Be independent
Be interdependent
115
Gender Roles
Our culture shapes our gender roles —
expectations of how men and women are
supposed to behave.
Gender Identity — means a how a person views
himself or herself in terms of gender.
116
Gender Roles: Theories
1. Gender Schema Theory: suggests that we
learn a cultural “recipe” of how to be a male
or a female, which influences our gender
based perceptions and behaviors.
2. Social Learning Theory: Proposes we learn
gender behavior like any other behavior —
reinforcement, punishment and
observation.
117
Reflections on Nature and Nurture
118