Biopsych test 2

epigenetics

a field that deals with changes in gene expression without modification of the DNA sequence

How does an epigenetic change differ from a mutation?

A mutation is a permanent change in part of a chromosome. An epigenetic change is an increase or decrease in the activity of a gene or group of genes.

How does adding a methyl or acetyl group to a histone protein alter gene activity?

Adding a methyl group turns genes off. An acetyl group loosens histone’s grip and increases gene activation.

heritability

estimate of the degree to which variation in a characteristic depends on genetic variations in a given population

What are the main types of evidence to estimate the heritability of some behavior?

The main evidence is greater similarity between monozygotic twins than dizygotic twins. Another is resemblance between adopted children and their biological parents.

artificial selection

a process of selecting plants/animals for desired traits

Lamarckian evolution

discredited hypothesis that the use or disuse of some body part will increase or decrease its size in the next generation, known as “inheritance of acquired characteristics,”

kin selection

selection for a gene that benefits the individual’s relatives

Under what condition would the effects of a recessive gene become evident?

Only if someone is homozygous for the gene

What does an epigenetic change do?

It increases or decreases the expression of a gene.

proliferation

production of new cells

stem cells

undifferentiated cells that divide and produce daughter cells that develop more specialized properties

What causes the first muscle movements in a developing embryo?

Spontaneous activity in the spinal cord.

New receptor neurons form in which sensory system?

olfaction

What evidence demonstrates that new neurons do not form in the human cerebral cortex?

The mean 14^C concentration in the DNA of cortical neurons corresponds to the year of birth

What was Sperry’s evidence that axons grow to a specific target instead of attaching at random?

If he cut connections to a newt’s eye and inverted the eye, axons grew back to their original targets, even though the connections were inappropriate to their new positions on the eye.

neural Darwinism

principle of competition among axons

nerve growth factor (NGF)

a protein that promotes the survival and growth of axons in the sympathetic nervous system and certain axons in the brain

apoptosis

a programmed mechanism of cell death

neurotrophin

a chemical that promotes the survival and activity of neurons

What process assures that the spinal cord has the right number of axons to innervate all the muscle cells?

The nervous system builds more neurons than it needs and discards through apoptosis those that do not make lasting synapses.

What class of chemicals prevents apoptosis in the sympathetic nervous system?

Neurotrophins, such as nerve growth factor

far transfer

improvement of a skill due to practice at a dissimilar skill

Why is immaturity of the prefrontal cortex not a satisfactory explanation for risky behaviors in adolescents?

As the teenage years progress, risky behavior tends to increase, even while the prefrontal cortex is becoming more mature.

stroke

A temporary loss of normal blood flow to a brain area

ischemia

type of stroke resulting from a blood clot or other obstruction in an artery

Under what condition would the effects of a recessive gene become evident?

only if someone is homozygous for the gene

what does a microdeletion remove?

part of a chromosome

In early human brain development which of these develops first?

muscle movements

How long does myelination continue in humans?

for decades

In which sensory system do new receptors continue to form throughout life?

olfaction

What did Rita Levi-Montalcini discover

sympathetic nervous system axons die if they do not connect to a muscle

diaschisis

decreased activity of surviving brain neurons after damage to other neurons

tissue plasminogen activator (tPA)

drug that breaks up blood clots

which of these is one way in which a stroke kills neurons?

excess glutamate stimulation

Which of these types of drugs decreases the damage from a stroke (if given promptly)?

cannabinoids

what causes diaschisis after a stroke

decreased input from damaged neurons

bipolar cells

type of neuron in the retina that receives input directly from the receptors

blind spot

area at the back of the retina where the optic nerve exits; it is devoid of receptors

color constancy

the ability to recognize colors despite changes in lighting

cones

A type of retinal receptor that contributes to color perception

fovea

a tiny area of the retina specialized for acute, detailed vision

ganglion cells

type of neuron in the retina that receives input from the bipolar cells

law of specific nerve energies

statement that whatever excites a particular nerve always sends the same kind of info to the brain

opponent-process theory

idea that we perceive color in terms of opposites

optic nerve

ganglion cell axons that exit through the back of the eye and continue to the brain

photopigments

chemicals contained in rods and cones that release energy when struck by light

pupil

an opening in the center of the iris where light enter

retina

the rear surface of the eye, which is lined with visual receptors

rods

type of retinal receptor that detects the brightness of light

what is the route from retinal receptors of the brain

receptors connect to bipolars, which connect to ganglion cells, which send axons to the brain

what axons form the optic nerve

axons from the ganglion cells

why is vision acute at the fovea

receptors in the fovea connect to midget ganglion cells

why does vision in the periphery have high sensitivity to faint light

toward the periphery, the retina has more convergence of input

why do some people have greater than average sensitivity to brief, faint, or rapidly changing visual stimuli

they have more axons from the retina to the brain

An object that reflects all wavelengths equally would ordinarily appear gray, but it may appear yellow, blue, or any other color, depending on what?

contrast with surrounding objects

color vision deficiency demonstrates which fundamental point about perception

color is in the brain and not in the light itself

feature detectors

neurons whose responses indicate the presence of a [articular feature

horizontal cells

type of cell that receives input from receptors and delivers inhibitory input to bipolar cells

koniocellular neurons

small ganglion cells that occur throughout the retina

lateral geniculate nucleus

thalamic nucleus that recives incoming visual info

lateral inhibition

the reduction of activity in one neuron by activity in neighboring neurons

magnocellular neurons

large cell bodies with large receptive fields that are disturbed evenly throughout the retina

parvocellular neurons

small cell bodies with a small receptive field in or near the fovea

retinal disparity

the discrepancy between what the left and right eye see

simple cell

A type of visual cortex cell that has a receptive field with fixed excitatory and inhibitory zones

strabismus

a condition in which the eyes do not point in the same direction (lazy eye)

what do horizontal cells in the retina do

they inhibit neighboring bipolar cells

In humans, what crosses to the contralateral hemisphere at the optic chiasm

half of each optic nerve, the part representing the nasal half of the retina

what is the function of lateral inhibition in the retina

to sharpen borders

parvocellular cells are specialized to respond to what

color and detail

magnocellular cells are specialized to respond to what

movement

which of these is true of visual imagery

it starts in language or memory areas and spread to V1

how do complex cells in the visual cortex differ from simple cells

complex cells make the same response after a stimulus moves

dorsal stream

visual path in the parietal cortex that helps the motor system locate objects “the where path”

fusiform gyrus

brain area of the inferior temporal cortex that recognizes faces

inferior temporal cortex

A portion of the cortex where neurons are highly sensitive to complex aspects of the shape of visual stimuli within very large receptive fields

medial superior temporal cortex (MST)

responds to the expansion, contraction, or rotation of a visual display

MT (V5)

are of the middle temporal lobe that is important for the perception of visual motion

prosopagnosia

the inability to recognize faces due to damage to several brain areas

saccades

voluntary eye movements

ventral stream

visual paths in the temporal cortex that are specialized for identifying and recognizing objects “the what path”

visual agnosia

an inability to recognize objects despite otherwise satisfactory vision

the dorsal stream of the visual system is specialized for which of these

coordinating vision with movement

what happens to receptive fields as we progress from V1, V2, V3, and beyond

they become larger and more complicated

what is distinctive about visual perception in the inferior temporal cortex

cells respond to an object regardless of the angle of view

the fusiform gyrus is specialized for which of the following

recognizing faces and other highly familiar objects

why is it difficult to watch your own eyes move when looking in the mirror

during saccadic eye movements, activity decreases in are MT

dermatome

area of the body connected to a particular spinal nerve

endorphins

transmitters that attach to the same receptors as morphine

gate theory

idea that stimulation of certain axons can close the “gates” for pain messages

opioid mechanisms

systems that respond to opiate drugs and similar chemicals

Pacinian corpuscle

receptor that responds to a sudden displacement of the skin or high frequency vibrations on the skin

periaqueductal gray

area of the brainstem that is rich in endorphin synapses

semicircular canals

structures located in the vestibular organ, oriented in three planes and lined with hair cells; sensitive to the directional tilt of the head

somatosensory system

sensory network that monitors the surface of the body and its movements

the vestibular system is responsible for which of these behavioral observations

people can read better while shaking their heads than while shaking the page

which of these experiences would cause the greatest stimulation in the semicircular canals

riding a roller coaster

to what extent does the nervous system maintain separate representations of touch, heat, pain, and other aspects of somatic sensation

different types of sensation remain separate even in the cerebral cortex

how do coldness receptors differ from heat receptors

coldness receptors adapt quickly to an unchanging temperature