Biopsychology Exam 2 - Chapter 4:

Explain how Mendelian genetics changed people's thoughts on genes:

- Until Mendel came up with his findings, people thought genes were from a sperm and eggs mix like paint

- he came up with the idea that inheritance occurs through genes

How did plant hybridization contribute to the foundation of modern genetics?

- pea plants were used to understand genetics

genes/how many do humans have?

most basic units of heredity that maintain their structural identity from one generation to another (pairs)

- 20,000

chromosomes

strands of genes (usually in pairs - 23 pairs)

genotype

notation of a gene pair (BB, bb, Bb)

phenotype

expression of the gene (what you see physically)

DNA

A gene is part of a chromosome, which is composed of a double-stranded molecule

RNA

- DNA is a model for RNA synthesis

- single strand chemical

What are the four DNA bases? What are the RNA bases?

DNA - adenine, guanine, cytosine, thymine

RNA - adenine, guanine, cytosine, uracil

homozygous

same genes on your two copies of some chromosomes

heterozygous

unmatched pair of genes

dominant vs recessive gene:

dominant - strong effect on homozygous or heterozygous

recessive - only shows effect for homozygous

sex-linked genes/ an example of one:

- genes on sex chromosomes (X and Y)

- on the 23rd pair

- Ex. Colorblindness - comes from disfunction of 1 gene and the X chromosome

autosomal genes

any non-sex linked genes

sex-limited genes

present in both sexes but mainly active in one sex

- show in puberty

-ex. breast size or chest hair

- on the other 22 pairs of genes (autosomes)

Explain the hairy back gene:

Testosterone triggers this - XY

- if women took testosterone, they could find out if they carry this gene

- sex-limited gene

Explain male pattern baldness:

- sex-limited gene

- both men and women have this gene but testosterone triggers it

- The more DHT receptors you have, the faster you will go bald because each time a receptor follicle falls out, it grows back less the next time

androgen

- testosterone is an example

- androgens turn genes on

Explain nature vs nurture:

- now a false dichotomy because we know you have both

How can your environment affect your appearance?

- works with nature and nurture

- you genes mixed with what you eat can affect your looks

- eat too many carrots and turn orange

- flamingos are pink if they eat certain foods

mutation

- a heritable change in a DNA molecule's base

- rarely advantageous

- could be duplication of deletion of a gene

- this take permanent` effect

Polydactylism

- having extra fingers or toes

- in some cases the trait is not expressed or shows on only one hand

- there are pro basketball or football players that are said to have an advantage due to this

Neurofibromatosis / variable expressivity:

- autosomal

- if you have just one gene for it, you will get it (dominant)

- regulatory elements can vary in expression

Ex.

- growths can press on bones and cause fractures

- benign schwann cell tumors can look super different depending on the family member with it - peripheral

epigenetics

- changes in gene expression/activity (phenotypes) without replacing the gene (an increase or decrease that is not permanent)

- every cell has the same DNA however gene expression will vary because genes are turned on and off

- forming new habits/learning from experience can change gene activity

- epigenetic changes can be inherited - ex. mother is sensitive to a certain smell and then the child is too

histones

- bind DNA into a shape that is more like a string wound around a ball

- its loose ends attach to chemical groups and can be effected by maternal deprivation, cocaine exposure, learning which all alter the chemical environment in the cell

Are behaviors genetically related?

- yes, but not religion

What happens when you add acetyl to a histone tail?

- histones loosen their grip on DNA and express the gene

What happens when you remove acetyl from a histone tail?

- histones tighten their grip and turn the gene off

What happens when you add or remove methyl from a histone? What might decrease it?

- add = turns off gene

- remove = turns on

- trauma decreases it causes a risk of depression later

heritability

- if variations in some characteristics depend largely on genetic differences, the characteristic has high heritability

- measured from 0(genetics have no control)-1(genetics have complete control)

What are two common ways that we determine heritability?

adoption and twin studies

- adoption - look at how they represent their biological parent

- monozygotic twins, dizygotic twins, and virtual twins (both adopted, same age, and grow up in same home) comparisons

candidate gene approach

identify specific genes linked to behavior

genome widespread association study/what is an issue with it?

- examines all genes while comparing two groups (ex. people with or without a disorder)

- test many hypotheses at once - could lead to the risk of seeing an apparent effect on accident

- Issue: a disorder may be common for a certain ethnic group - these common genes become a risk factor when they are not

Give an example of heritable traits being altered by the environment:

- PKU - can not metabolize phenylalanine (you put your kid on a low protein diet to help

evolution

a theory (scientific theory - has been tested over and over again to try to refute it NOT prove it right)

- science has no laws or proofs - has theories

- facts can change

Who do we have a common ancestor with?

all animals

Was Darwin the first one to come up with evolution?

no

Did we evolve from modern day monkeys?

No! We just have a common ancestor

artificial selection

Choose individuals with a desired trait and make them the parents of the next generation (dog breeders)

Lamarckian Evolution

- the use or disuse of a structure/behavior causes an evolutionary increase or decrease

Have humans stopped evolving?

- misconception! they have not

- people say this because we now have meds that could keep us alive forever

Evolution is not just living; it is about reproduction

Does evolution always mean improvement?

- no

- evolution improves fitness which is the number of copies of one's genes that survive in future genes

- something that was an improvement in the past may not be an improvement in the future

what does evolution benefit?

not the individual or the species it benefits THE GENE

- spreads genes

evolutionary psychology/an example:

- concerns how behaviors evolved

- Sometimes we have traits because they helped our very distant ancestors - ex. Goosebumps help animals with lots of thick fur when they are cold, but not us

altruistic behavior

- action that benefits someone other than the actor

- not common for non-humans

kin selection

- selection for a gene that benefits the individual's relatives

- if your gene makes you brave enough to save your child's life, it is being passed on since they will live to reproduce

reciprocal altruism

- the idea that individuals help those that'll return the favor

- you must be able to recognize people - remember that they have helped someone (it does not need to be you) - you will be more likely to help them

group selection / the issue with it:

- altruistic groups thrive better than less cooperative ones

- Problem: In competitive groups, the one that is not altruistic benefits a lot

evolutionary change

people with certain genes reproduce more than average

evolution of behavior

- change in the gene pool over generations in a population cause behavior change

- change happens through mutation, recombination, and deletion

- new genes must be reproduced

fitness

reproductive success

homeobox genes

- regulate expression of other genes and control the start of anatomical development

- effects vertebrates, insects, plants, fungi, yeast

What could a mutation to homeobox genes do?

- make an insect have legs where their antenna should be

- give humans mental disorders

Explain brain growth:

- rows from infancy to adulthood (triples in size)

Explain what the cortex enables infants to do:

- can see, hear, and take in senses but the prefrontal cortex is still developing which is what helps them interpret and act on information

proliferation

- Production of new cells - produce way more than needed in utero and some may die which is a good thing

- almost all neurons are proliferated before birth (most neurons before or right after birth)

- cells in the ventricles divide, some stay as stem cells in the same area and some become neurons or glia in a new location

stem cells

- UNDIFFERENTIATED - can become any cell

- some cells remain on the ventricles when division happens continuing to divide

Others migrate to other parts of the NS

migrate

- primitive cells move with the help of chemicals

- the lack of these cells can lead to decreased migration, decreased brain size, and mental retardation

- radial glia assists with this

differentiation

cell becomes a neuron forming dendrites, axons and synapses

synaptogenesis

formation of synapses (starts before birth and continues through life)

myelination

glia produce the insulating fatty sheaths that accelerate transmission

- last part to "solidify in a human"

- up to 20-25 years old (probably even longer

growth cone

hand-like structure at the tip of the axon

What is the order of proliferation?

Migration, synaptogenesis, myelination

What did Cajal believe about neuron development/was it correct?

- thought all neurons were developed by early infancy

- new neurons form in the olfactory bulb for many species (not humans)

- new neurons form in the hippocampus when there are new memories

What happens to neurons in the brain when you learn something new?

- create new neurons in the hippocampus and the basal ganglia

- know this because the concentration of 14C matches the recent years for newer memories

Explain the Weiss/Salamander experiment:

- added an extra leg to a salamander

- moved in synchrony with its neighbor because each neuron found the correct muscle

- when the extra leg attacked the axon was looking for a chemical gradient and it found the right one

Explain Roger Sperry's findings:

- used newts (amphibians, not mammals) who can grow back their optic nerve and cut the nerve to see where it grew back to

- grew back to the same place that it was originally following a chemical trail

neural Darwinism

- with NS development, we start with more neurons and synapses than we can keep and a selection process keeps some synapses and rejects the others

- spontaneous activity during development helps axons fine tune where they attach based on experiences

What was Levi-Montalcini's theory/what ideas did he have?

- muscles determine how axons survive

- nerve growth factor, apoptosis, neurotrophin

nerve growth factor (NGF)

- a protein that promotes the survival and growth of an axon delivered when a neuron forms a synapse on a muscle

- cancels out apoptosis when a connection is made

apoptosis

- ensures that there is the correct number of neurons

- programmed mechanism of cell death if the neuron doesn't make contact with the right postsynaptic cell by a certain age

- important in development AND adult life

What are the two conditions required for survival?

1) Sending neuron forms synapse with a target cell, obtaining NGF from it - a neurotrophin

2) sending neuron releases neurotransmitters

neurotrophin

- a chemical that promotes the survival and activity of neurons (NGF)

- essential for motor neurons in the periphery but not the brain

- prevents apoptosis

gastrulation

- early embryonic development / most important time of life

How does alcohol affect gastrulation?

- fetal alcohol syndrome: causes hyperactivity, impulsiveness, hard time paying attention, mental retardation, motor problems, heart defects, facial abnormalities

- alcohol impairs proliferation, migration, differentiation, and synaptic transmission

- alc dec glutamate and increases GABA which causes a lack of excitatory messages which can lead to apoptosis (anesthetic drugs and anxiety reducing drugs also increase GABA)

Explain sensory input's effect on young neurons:

- young neurons can adapt based on sensory input

- Ex. Ferrets had one side of their vision impaired so those neurons went to auditory areas and some vision was processed there instead

How are dendrites affected by learning, enriched environments, and physical activity?

- they grow or retract based on learning

- Ex. Rats in the wild have thicker cortexes and more dendritic branches because their are in a more enriched environment than lab rats

- physical activity enhances growth of axons and dendrites (for rats and humans)

Explain far transfer:

- this has a weak effect

- the idea that education is seen as a way to do something difficult that will enhance intellect in general

What have we found from using magnetic temporary deactivation on blind people?

- people who are blind use their touch and hearing more than the average person and are better at identifying these than a sighted person

- the occipital lobe is active when reading braille (even though the person is not seeing it) and can not read when it is deactivated

How are people who play music's brains different?

- different brains to help them hear music, the changes are a result of musical training

- commonly used brain areas are enlarged

- the younger you start, the greater changes in sensory discriminations and brain anatomy

focal hand dystonia

- when moving 1 finger without another, it is hard (musicians cramp)

- extensive practice of instruments causes extended representation of fingers in the somatosensory cortex and displacement of finders in the motor cortex - too much representation of the fingers overlap and the person can not move them seperate

- Treatment: proprioceptive training - vibrate muscles and train person to reach for targets

Adolescents on risky behavior:

- less developed prefrontal cortex - more impulsive or risky

- experiences also make them more likely to take risks

- interesting because risk-taking is on a bell curve, highest in teenage years despite the prefrontal cortex being more developed than in younger years

- increased activity in brain areas anticipating reward in teen years = more risky

Old age and cortical activity/memory:

- decreased memory/reasoning

- some peoples hippocampus deteriorate and some do not

- might be slower but have more experience and knowledge than younger people (take power)

- compensate for losses by activating more widespread brain areas to compensate for decreased arousal in others

- daily exercise increases cortical activity and memory

Explain rat studies about old age:

- when young rats blood is injected into older rats there is more plasticity in their learning

What is the order of development for humans?

Vision, movement, and then other sensory systems

What is likely to deteriorate with alzheimer's:

- prefrontal cortex (area of the cerebral cortex) - matures at a late age

closed head injury

- most common cause of brain damage in young people

- a sharp blow to the head that does not puncture the brain (come at dif severities - not always need treatment)

-recent memory or confusion = long term effects

What are the two ways you can be effected by a closed head injury?

- damage could occur to the rotational forces that drive the brain tissue against the inside of the skull

- Blood clots could interrupt blood flow to the brain

Explain why woodpeckers do not have closed head injuries?

- keep a rigid neck to avoid whiplash

If football helmets went to shoulders, it would help a lot with this

Cerebrovascular accident

- a stroke - temporary interruption of normal blood flow to the brain (causing brain damage)

What is the most common stroke?

- ischemia - form a blood clot or artery obstruction

- loose oxygen and glucose for the brain

hemorrhage

- common stroke

- ruptured artery causes neurons to flood with excess oxygen, calcium, and chemicals

What are two effects of strokes?

- Edema - accumulation of fluid, increases pressure in the brain, and increases the probability of more strokes

- Inhibits the sodium potassium pump - too much sodium in the neuron - excessive glutamate release (damages neurons and synapses)

Stroke treatments:

- Tissue Plasminogen Activator (tPA)

- Cannabinoids

- blocking calcium or glutamate

Tissue Plasminogen Activator (tPA)

breaks up blood clots if used within 4.5 hours (Could make it worse for a hemorrhage but these are less common and an MRI would take too long to find out what kind of stroke so it is likely used - plus you would probable die anyways from one)

Research on blocking calcium and glutamate to treat strokes:

- since strokes overstimulate and kill neurons it would be good to dec APs and excitatory messages

- promising on animals but animals are healthy before and are treated directly after the stroke so this may not be applicable

Cannabinoid effects on strokes:

- decrease glutamate and exert anti-inflamitory effects on the brain

- more effective if taken before a stroke - most people that smoke are younger, so it could be that they recover better

Diaschisis

- decreased activity of surviving neurons after damage to other neurons

- they are not receiving the messages from damages neurons anymore

Treatment on diaschisis:

- if this contributes to behavioral deficits, increase stimulation

- use drugs that increase dopamine release o the cells that had been receiving information from others

Do axons grow back?

- not for mammalian brain or spinal cord