Week 1: Genetics, Evolution, and Methods

Question 1

Artificial Selection

Answer 1

breeders chose plants/animals w/ desirable traits and make them parents of next generation
- requires variation, heritability
- breeder ensures some individuals reproduce more successfully, genes become more prevalent

Question 2

Chromosomes

Answer 2

strands of genes composed of DNA

Question 3

Deoxyribonucleic Acid (DNA)

Answer 3

recipe for proteins

Question 4

Dizygotic Twins

Answer 4

don’t share any more genes than other siblings

Question 5

Dominant Gene

Answer 5

effect in either homozygous or heterozygous condition

Question 6

Epigenetics

Answer 6

changes in gene expression without changing the DNA
- some genes more active at certain times
- changes in gene expression = central to learning/memory

Question 7

Evolution

Answer 7

change over generations in the frequencies of various genes in a population
- parents pass traits to offspring
- new genetic variations appear
- reproductive success = genes passed on

Question 8

Genes

Answer 8

units of heredity (something that can be passed down)

Question 9

Genetics

Answer 9

complex as:
- many genes can contribute to one outcome
- genes can be expressed differently in different body regions
- genes can be expressed in some circumstances, not in others
- behavior is a combination of genetic influences and environmental influences

Question 10

Heritability

Answer 10

the ability of a trait to be passed to offspring

studied using:
- MZ and DZ twins
- adopted children
- biochemical methods

Question 11

Heterozygous

Answer 11

unmatched pair of genes

Question 12

Homozygous

Answer 12

identical pair of genes on two chromosomes

Question 13

Lamarckian Evolution

Answer 13

disproved theory stating organisms can pass on acquired traits to offspring
- ex: giraffes stretched necks to reach leaves + passed on the stretched neck, not true

Question 14

Monozygotic Twins

Answer 14

share genes

Question 15

Mutation

Answer 15

heritable change in DNA
- change the DNA, change the protein

Question 16

Recessive Gene

Answer 16

effects only in homozygous condition

Question 17

Genotype

Answer 17

full hereditary information

Question 18

Phenotype

Answer 18

actual observed properties

Question 19

Ablation

Answer 19

removal of brain area

Question 20

Computerized Axial Tomography (CT or CAT scan)

Answer 20

• head placed into scanner
• x-rays sent thru head & recorded on opposite side
• scanner rotates around head, measurements @ each angle
• dense structures (bone) appear white, less dense (air) appear dark
• gray/white matter = more dense than CSF
• fat: less dense than water

Question 21

White Matter

Answer 21

higher far content (myelin) than gray matter, appears darker

Question 22

Hyperdense

Answer 22

brighter than brain

Question 23

Hypodense

Answer 23

darker than brain

Question 24

Electroencephalograph (EEG)

Answer 24

electrical activity from brain recorded through electrodes attached to scalp
- average activity of population of cells under electrode
- can record activity in response to stimulus (event-related potentials)

Question 25

Pros and Cons of EEG

Answer 25

Excellent temporal resolution (ms by ms) - Electrical signal = direct measure of brain activity Limited spatial resolution - over a population of cells - scalp/skull/brain tissue blur electrical signal - signal varies with cortical depth + orientation of neurons

Question 26

Lesion

Answer 26

damage to brain area

Question 27

Evoked Potentials/Responses

Answer 27

activity in response to a stimulus

Question 28

functional Magnetic Resonance Imaging (fMRI)

Answer 28

measures changes in blood flow and oxygen content in blood - scanner: strong magnet - magnetic properties of blood let you see brain activity more active brain area: - more blood flow - less oxygen in blood

Question 29

Pros and Cons of fMRI

Answer 29

good spatial resolution (mm) poor temporal resolution - hemodynamic response starts 1-2s after neurons fire and peaks after ~6s (typically use ms so s is slow) MRI scanner = strong magnet which limits who can participate scanner is small and noisy can't move, limits tasks/responses

Question 30

Magnetic Resonance Imaging (MRI)

Answer 30

uses powerful magnetic field tissues with different water content react different to magnet - CSF: most water - gray matter: some water - white matter: least water (myelinated)

Question 31

Magnetoencephalography (MEG)

Answer 31

measures tiny magnetic fields generated by brain activity - magnetic activity less impacted by scalp (better spatial resolution)

Question 32

Positron-Emission Tomography (PET)

Answer 32

inject radioactive chemical used by brain (typically glucose) - emits gamma rays as it decays - scanner picks up on where rays came from - more radiation = presumably more brain activity

Question 33

Stereotaxic Instrument

Answer 33

device precisely places electrode in brain - animal is anesthetized, hole drilled in skull, electrode inserted/put into position, pass current to damage area

Question 34

Transcranial Magnetic Stimulation (TMS)

Answer 34

apply intense magnetic field to part of scalp, temporarily inactivates neurons - measure before, during, and after inactivation

Question 35

Diffusion Tensor Imaging (DTI)

Answer 35

white matter connectivity looks at direction of water movement - water easily flows down axon compared to across an axon

Question 36

Sham Lesion

Answer 36

everything but crrent

Question 37

Spatial

Answer 37

where something is happening

Question 38

Temporal

Answer 38

when something is happening

Question 39

Natural Selection

Answer 39

gradual process by which traits become more/less common as a function of reproductive success (fitness)