Transcript OpenStax_Psychology chapter 3 genetics and the brain

PSYCHOLOGY
Chapter 3 BIOPSYCHOLOGY
PowerPoint Image Slideshow
CHAPTER TOPICS
•Genetics and DNA
•Evolution by Natural Selection
•The Genetics and Evolution of Behavior
•The Experience Dependent Brain
•Building Blocks of the Nervous System and Brain
•Communication among Neurons
CHAPTER TOPICS
•Methods for Studying the Nervous System
•The Architecture of the Nervous System
•The Cerebral Cortex
•Plasticity
•Some Final Thoughts: Do All Psychological
Questions Have Biological Answers?
•Summary
FIGURE 3.3
(a) In 1859, Charles Darwin proposed his theory of evolution by natural selection in his
book, On the Origin of Species.
(b) The book contains just one illustration: this diagram that shows how species evolve
over time through natural selection.
DARWIN AND EVOLUTION
•Charles Darwin hypothesized that all modern
organisms:
• are descended from a small set of shared
ancestors.
• have emerged over time through the
process of evolution.
•An enormous amount of evidence has
confirmed these proposals.
DARWIN AND EVOLUTION
•The key mechanism is natural selection.
• If individuals with certain traits are more likely to
survive and reproduce,
• their genes will be better represented in the
next generation.
• And if the genes gave rise to the advantageous
traits,
• those traits will be more common in the next
generation.
NATURALISTIC FALLACY
•It is important to avoid the naturalistic
fallacy, however—it does not follow that
evolution somehow improves organisms or
that anything natural is good.
•This means the genotypes and phenotypes
that are passed on to survive allow the
organisms to survive. It does not necessarily
mean this is good or bad.
•Can you think of examples?
QUIZ 1
Please define natural
selection.
What is the naturalistic
fallacy?
GENETICS AND DNA
•The nucleus of each biological cell contains
chromosomes, which each contain a single
molecule of DNA.
•Within this molecule, genes govern the cell’s
functioning by providing detailed instructions
for making proteins. This a very complex
process.
MAKING PROTEINS
The genes contain the information needed to
make proteins. This allows the information in the
gene to be expressed for the genotype.
A genotype is your complete heritable genetic
identity. It is written in code (your DNA). This is the
“nature” meaning what you inherit from your
parents. It is the way your genes are “expressed”.
GENOTYPE AND PHENOTYPE
Phenotype: This is the description of your actual
physical characteristics, temperament, personality,
etc. This is influenced by your genotype and by
your environment.
The phenotype and genotype are in constant
interaction.
Why do we need to know this information for the
study of psychology?
FIGURE 3.4
(a) Genotype refers to the genetic makeup of an individual based on the genetic material (DNA)
inherited from one’s parents.
(b) Phenotype describes an individual’s observable characteristics, such as hair color, skin color,
height, and build. (credit a: modification of work by Caroline Davis; credit b: modification of work
by Cory Zanker)
DOMINANT VS. RECESSIVE
•The genes may or may not be the same allele.
Ex: blue eyes (allele) from mom and brown eyes
(allele) from dad.
•Geneticists use the terms dominant and recessive
to describe the inheritance patterns of certain
traits. In other words, how likely is it for a certain
phenotype to pass from parent to offspring.
•These terms are used to predict the probability of
someone inheriting a phenotype.
DOMINANT AND RECESSIVE
Organisms have two alleles for each trait.
One allele may be dominant (so it is expressed)
and the other is recessive (so it is masked).
Co-dominant is when both alleles are expressed
(AB blood type).
Incomplete dominant is when both alleles mix,
as in flowers. This means both traits are shown
and not masked.
FIGURE 3.5
(a) A Punnett square is a tool used to predict how genes will interact in the production of offspring. The
capital B represents the dominant allele, and the lowercase b represents the recessive allele. In the
example of the cleft chin, where B is cleft chin (dominant allele), wherever a pair contains the dominant
allele, B, you can expect a cleft chin phenotype. You can expect a smooth chin phenotype only when
there are two copies of the recessive allele, bb.
(b)
A cleft chin, shown here, is an inherited trait.
GENE EXPRESSION
•In each cell, some genes are expressed, or
activated in some way, at any point in time and
others are not.
•Gene expression is controlled by the biochemical
environment inside the cell, which is influenced by
the organism’s:
• Overall environment.
• Experiences and Behaviors.
QUIZ 2
Please define Genome?
What is a genotype?
What is a phenotype?
What does “gene expression” mean?
Please define the naturalistic fallacy.
FIGURE 3.7
Nature and nurture work together like complex pieces of a human puzzle. The
interaction of our environment and genes makes us the individuals we are. (credit
“puzzle”: modification of work by Cory Zanker; credit “houses”: modification of work by
Ben Salter; credit “DNA”: modification of work by NHGRI)
THE DIATHESIS STRESS MODEL
https://youtu.be/ayWVkmYH6TY
A person’s genetic predisposition,
combined with psychological stressors,
are what cause someone to become ill.
GENETICS IN PSYCHOLOGY
Heritability refers to a statistic of proportion (the
part in relation to the whole) to explain how likely
we are to inherit something through our genetics.
The numbers range from 0.0, where we see that
genes do not contribute at all to phenotypic
individual difference or the overt traits and
behaviors, to 1.0 where genes are the only reason
for these differences.
GENETIC EPIDEMIOLOGY OF SELECTED MENTAL
HEALTH ISSUES
Prevalence
Paternal
Age onset Mortality
Fertility Heritability
(%)
age effect
0.30
1
2.0
0.05
0.90
1.4
Autism
Anorexia
0.60
nervosa
Schizophre
0.70
nia
Bipolar
affective 1.25
disorder
Unipolar
10.22
depression
Anxiety
28.80
disorders
15
6.2
0.33
0.56
—
22
2.6
0.40
0.81
1.4
25
2.0
0.65
0.85
1.2
32
1.8
0.90
0.37
1
11
1.2
0.90
0.32
—
Molecular Psychiatry (2009) 14, 1072–1082; doi:10.1038/mp.2009.85; published online 25 August 2009
The role of genetic variation in the causation of mental illness: an evolution-informed framework. By R. Uher.
GENETIC PREDISPOSITION
The likelihood of inheriting something based on
genetic makeup.
Prevalence refers to proportion of the population
found to have a condition. This one is number of
cases per 100 people.
Incidence means the number of new cases in a
population at a given time.
What do you believe are the factors involved that
create the illness when someone has a genetic
predisposition?
OUTSIDE FORCES
ILLNESS
Anorexia
Autism
Schizophrenia
Bipolar Disorder
Major Depression
Generalized Anxiety
OCD
OTHER CAUSES
Related to being white,
female, and in a Western
Culture.
Diagnosis has increased
with time.
Increased risks living in
urban environment and
being an ethnic minority.
Depression 1 in 10 people.
MTHFR, 1/3 in lifetime.
MENTAL HEALTH BOOSTER
CELLS OF THE NERVOUS
SYSTEM
Identify the basic parts of the Neuron
Describe how neurons communicate with
each other
Explain how drugs act as agonists or
antagonists for a given neurotransmitter
system
NEURONS AND GLIA CELLS
THE MAIN CELLS IN YOUR CENTRAL NERVOUS SYSTEM.
NEURONS ARE THE INFORMATION PROCESSING STRUCTURES WITHIN YOUR
BRAIN AND CNS.
WHAT IS INFORMATION PROCESSING?
GLIA CELLS SUPPORT THE NEURONS IN THEIR EFFORT TO PROCESS, SEND,
PROCESS, AND RECEIVE INFORMATION. THEY ARE THE FOUNDATION AND
STRUCTURES THAT ALLOW NEURONS TO DO THEIR JOB.
NEURONS RECEIVE INPUT FROM OTHER NEURONS, PROCESS AND MAKE
SENSE OF THIS COMMUNICATION, AND SEND OUTPUT TO ANOTHER
NEURON(S) BASED ON THE COMMUNICATIONS THEY RECEIVED.
NEURONS CONTROL THE FLOW FOR ALL MOTOR, SENSORY, AND COGNITIVE
INFORMATION TO RUN THE UNIQUE BRAIN AND BODY THAT IS YOU.
THIS WHOLE PROCESS IS VERY CHAOTIC!
NOW FOR BACKGROUND INFORMATION….
THE STRUCTURE OF THE NEURON
• THERE ARE OVER 10,000 TYPES OF NEURONS.
• THERE ARE MOTOR NEURONS CONTROLLING MOVEMENTS, SENSORY
NEURONS, AND COGNITVE NEURONS.
• YOUR NEURONS CONTAIN FOUR PARTS:
• A CELL BODY THAT FUNCTIONS AS THE METABOLIC MANAGING CENTER.
• PROCESSES THAT ARE CONDUITS TO INFORMATION FLOW: THOUSNDS OF
DENDRITES THAT RECEIVE SIGNALS FROM OTHER NEURONS and ONE
AXON THAT SENDS AN OUTGOING SIGNAL.
• AXON TERMINALS THAT CONTAIN THE NEUROTRANSMITTERS THAT SEND
CHEMICAL SIGNALS BETWEEN NEURONS.
FIGURE 3.8
This illustration shows a prototypical neuron, which is being myelinated.
QUIZ 3
What are the four parts of the neuron?
What do each of these four parts do?
Draw a picture of a neuron. Please label
each part.
NEUROTRANSMISSION:
COMMUNICATION BETWEEN
NEURONS
THIS BEGINS WHERE ELECTRICAL CONDUCTION IS LEFT
OFF WHICH IS AT THE AXON TERMINALS.
NEUROTRANSMISSION HAPPENS AT THE SYNAPSES.
THERE ARE TWO TYPES OF TRANSMISSIONS: CHEMICAL
SYNAPSES AND ELECTRICAL SYNAPSES. MOST
TRANSMISSIONS ARE CHEMICAL.
NEUROTRANSMISSION VIA THE SYNAPSES
NEURONS HAVE NO CONTINUTITY BETWEEN NEURONS MEANING
THEY ARE NOT CONNECTED.
A SYNAPSE IS THE GAP BETWEEN EACH NEURON. THIS BOUNDARY
IS SELECTIVE WHICH CAN BE BAD OR GOOD.
NEUROTRANSMITTERS FUNCTION AS THE MESSENGER ACROSS
THIS GAP.
THEY ARE SPECIALIZED CHEMICALS THAT ALLOW THE NEURONS TO
COMMUNICATE WITH EACH OTHER. THEY EITHER EXCITE OR INHIBIT
ACTION BETWEEN THE NEURONS.
EXAMPLES ARE SEROTONIN, DOPAMINE, NOREPINEPHRINE, AMINO
ACIDS, HISTAMINE, ETC.
THEY TELL YOUR HEART TO BEAT, YOUR STOMACH TO DIGEST, AND
AFFECT YOUR MOOD, SLEEP, WEIGHT, ETC.
FIGURE 3.9
(a) The synapse is the space between the terminal button of one neuron and the dendrite of another neuron.
(b) In this pseudo-colored image from a scanning electron microscope, a terminal button (green) has been
opened to reveal the synaptic vesicles (orange and blue) inside. Each vesicle contains about 10,000
neurotransmitter molecules. (credit b: modification of work by Tina Carvalho, NIH-NIGMS; scale-bar data
from Matt Russell)
SYNAPTIC TRANSMISSION
CHEMICAL TRANSMISSION OF INFORMATION ALLOWS
THE NEURONS MORE CONTROL OVER THE
COMMUNICATION.
THE FOLLOWING PROCESS OCCURS:
THE ACTION POTENTIAL ARRIVES AT THE AXON
TERMINAL (THE END OF THE AXON).
ION CHANNELS OPEN FOR COMMUNICATION TO OCCUR.
THE IONS ENTER THE PRESYNAPTIC NEURON.
THE IONS BIND WITH OTHER CHEMICALS. THIS ALLOWS
THE VESICLES TO MERGE WITH THE PRESYNAPTIC
MEMBRANE. THIS MERGE ALLOWS THE
NEUROTRANSMITTERS TO BE RELEASED IN THE SYNPTIC
CLEFT.
AS THE NEUROTRANSMITTERS RELEASE INTO THE SYNAPTIC CLEFT, THEY
DIFFUSE THROUGH THE MEMBRANE (THE MEMBRANE IS SEMI PERMEABLE).
NOW THE NEUROTRANSMITTER BINDS WITH THE MEMBRANES AT THE ENDS
OF BOTH CELLS (THE SENDER CELL WHICH IS PRESYNAPTIC AND THE
RECEIVER CELL THE POST SYNAPTIC). THIS IS EITHER DIRECT (JUST
HAPPENS) OR INDIRECT (CAUSES THE RELEASE OF A SECONDARY
MESSENGER).
THIS CAN CAUSE TWO RESPONSES FROM THE RECEIVER CELL (POST
SYNAPTIC). THE RESPONSE IS EITHER AN EXCITATORY OR INHIBITORY.
FIGURE 3.10
At resting potential, Na+ (blue pentagons) is more highly concentrated outside the cell in the
extracellular fluid (shown in blue), whereas K+ (purple squares) is more highly concentrated
near the membrane in the cytoplasm or intracellular fluid. Other molecules, such as chloride
ions (yellow circles) and negatively charged proteins (brown squares), help contribute to a
positive net charge in the extracellular fluid and a negative net charge in the intracellular fluid.
QUIZ 5
Please explain chemical neural
communication.
FIGURE 3.11
During the action potential, the electrical charge across the membrane changes
dramatically.
FIGURE 3.12
Reuptake involves moving a neurotransmitter from the synapse back into the axon
terminal from which it was released.
FIGURE 3.13
The nervous system is divided into two major parts:
(a) the Central Nervous System and
(b) the Peripheral Nervous System.
FIGURE 3.15
The surface of the brain is covered with gyri and sulci. A deep sulcus is called a fissure,
such as the longitudinal fissure that divides the brain into left and right hemispheres.
(credit: modification of work by Bruce Blaus)
FIGURE 3.16
(a, b) The corpus callosum connects the left and right hemispheres of the brain. (c) A
scientist spreads this dissected sheep brain apart to show the corpus callosum
between the hemispheres. (credit c: modification of work by Aaron Bornstein)
THE STRUCTURE AND THE
FUNCTION OF THE BRAIN
https://youtu.be/kMKc8nfPATI
Discussion of the CNS and the PNS
The CNS consists of the brain and spinal
cord.
The PNS consists of the nerves and ganglia
(nerve cell clusters) outside of the brain and
spinal cord.
FIGURE 3.17
The brain and its parts can be divided into three main categories: the forebrain,
midbrain, and hindbrain.
FIGURE 3.18
The lobes of the brain are shown.
FIGURE 3.19
(a) Phineas Gage holds the iron rod that penetrated his skull in an 1848 railroad construction
accident.
(b) Gage’s prefrontal cortex was severely damaged in the left hemisphere. The rod entered Gage’s
face on the left side, passed behind his eye, and exited through the top of his skull, before
landing about 80 feet away. (credit a: modification of work by Jack and Beverly Wilgus)
QUIZ 1
How do scientists learn about the inner workings
of the human brain?
Who is Phinneas Gage? How is what happened
to him significant for neuroscience?
You will need to know the structures and their
functions of the brain as discussed in the video.
What study methods will you use to remember this
information?
FIGURE 3.20
Spatial relationships in the body are mirrored in the organization of the somatosensory
cortex.
FIGURE 3.21
Damage to either Broca’s area or Wernicke’s area can result in language deficits. The
types of deficits are very different, however, depending on which area is affected.
FIGURE 3.22
The thalamus serves as the relay center of the brain where most senses are routed for
processing.
FIGURE 3.23
The limbic system is involved in mediating emotional response and memory.
FIGURE 3.24
The substantia nigra and ventral tegmental area (VTA) are located in the midbrain.
FIGURE 3.25
The pons, medulla, and cerebellum make up the hindbrain.
FIGURE 3.1
Different brain imaging techniques provide scientists with insight into different aspects of how the
human brain functions. Left to right, PET scan (positron emission tomography), CT scan (computed
tomography), and fMRI (functional magnetic resonance imaging) are three types of scans. (credit
“left”: modification of work by Health and Human Services Department, National Institutes of Health;
credit “center”: modification of work by “Aceofhearts1968”/Wikimedia Commons; credit “right”:
modification of work by Kim J, Matthews NL, Park S.)
FIGURE 3.26
A CT scan can be used to show brain tumors. (a) The image on the left shows a
healthy brain, whereas (b) the image on the right indicates a brain tumor in the left
frontal lobe. (credit a: modification of work by “Aceofhearts1968”/Wikimedia Commons;
credit b: modification of work by Roland Schmitt et al)
FIGURE 3.27
A PET scan is helpful for showing activity
in different parts of the brain. (credit:
Health and Human Services Department,
National Institutes of Health)
FIGURE 3.28
An fMRI shows activity in the brain over
time. This image represents a single
frame from an fMRI. (credit: modification
of work by Kim J, Matthews NL, Park S.)
FIGURE 3.29
Using caps with electrodes, modern EEG research can study the precise timing of
overall brain activities. (credit: SMI Eye Tracking)
BRAIN ILLNESS/INJURY AND
DEPRESSION
Stroke can cause paralysis, speech
problems, and an inability to complete daily
tasks.
Depression and stroke and heart attack are
linked.
Seizures happen when the brain cells, which
communicate through electrical signals, send
out the wrong signals.
SEIZURES
In about half the cases the cause is not
known.
Causes include head injury, genes,
dementia, brain injury, lupus, meningitis,
stroke, heart attack.
Treatment may include brain removal.
BRAIN INJURY
Post Concussive Syndrome
https://youtu.be/N9S_Hdkqf08
Other Traumatic Brain Injury
https://youtu.be/HxaNeE7Qzn4
Due to illness of medications
http://www.cbsnews.com/videos/u-s-troops-given-anti-malaria-drugdespite-concern-of-side-effects
QUIZ 6
What is an experience-dependent brain?
What is plasticity?
What is an experience-expectant brain?
What are two types of brain injury?
Can your brain be injured due to medications
or illegal drug use?
PLASTICITY IN ACTION
http://bigthink.com/think-tank/brain-exercise
Another example of neuroplasticity has been
found in London taxi drivers. A cab driver's
hippocampus -- the part of the brain that holds
spatial representation capacity -- is measurably
larger than that of a bus driver. By driving the
same route every day, the bus drivers don't need
to exercise this part of the brain as much. The
cabbies, on the other hand, rely on it constantly for
navigation.
FIGURE 3.30
The major glands of the endocrine system are shown.
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