psyc midterm 2

neurons

basic unit of brain structure

• 86 billion neurons in brain

• communicate with other neurons

4 main parts of neuron

1. dendrite

2. cell body (soma)

3. axon

4. axon terminal

cell body (soma)

part of neuron

central region of the neuron that manufactures proteins and renews cell components

• contains nucleus

dendrite

part of neuron

• receive inputs from other neurons (branch like)

axons

send signals to other neurons

• releases neurotransmitters

• wrapped around by myelin sheath (created by glial cells)

part of neuron

axon terminal

end part of axon that makes synaptic contact with another cell

glial cells

cells in brain along with neurons, same number of them as neurons

glial cells 5 functions

1. main function- form myelin sheath

2. grow around neurons, protecting them

3. digest dead neurons

4. heal neurons by releasing chemicals

5. help communicate with neurons

action potential

electrical signal that is conducted along the length of an axon to the synapse, massive reversal of membrane potentail from -70mV to +50mV

• occurs when EPSP and IPSP is larger than the threshold, not when neuron is hyperpolarized

action potential 5 steps

1. resting state at -70mV, resting potential

2. depolarization - getting less charged from -70mV to 0

   • another neurotransmitter from another neuron stimulates one of the neurons channel to open, causing sodium (Na+) ions to tenter, depolarizing the area

   • if potential reaches threshold, cell fires, action potential is triggered

3. rising phase

   • more channels open = more Na+ enter

   • new Na+ channels bc of depolarization

4. falling phase

   • Na+ channels close, potassium K+ channels open

   • K+ leaves making potential more negative

5. undershoot

   • refractory period

   • cell can’t fire again/have another action potential

resting potential

when the cell is not stimulated -70mV

• calc: inside cell - outside cell = resting potential

refractory period

when the cell is hyperpolarized, even more negative than resting state

membrane potential

difference in the charge between the inside and outside of the cell

EPSP

excitatory post synaptic potential

• depolarized post synaptic membrane

• inc likelihood that neuron will fire

IPSP

inhibitory post synaptic potential

• hyperpolarized post synaptic membrane

• dec likelihood that neuron will fire

types of neurotransmitters

1. glutamate

2. gamma amino butyric acid (GABA)

3. acetylcholine

4. dopamine

5. serotonine

6. norepinephrine

7. endorphins

glutamate

major excitatory neurotransmitter in brain

• most common in brain

• learning, enhanced memory, relaying sensory info

gamma amino butyric acid (GABA)

major inhibitory neurotransmitter

• learning, memory, sleep

acetylcholine

type of neurotransmitter

• functions 2 ways

  • PNS - voluntary muscle action

  • brain - learning, memory, sleep/dreaming

dopamine

type of neurotransmitter

• regulates motivation and pleasure, emotional arousal, motor behavior

• sex, drugs, eating, addiction

serotonin

type of neurotransmitter

• regulation of sleep and wakefuleness

• involved in depression

norepinephrine

type of neurotransmitter

• vigilance, heightened awareness of dangers

endorphins

type of neurotransmitter

reduce pain, elevates mood

synapse

communication btwn neurons

how does presynaptic neuron regulate amount of neurotransmitters in synaptic cleft (3 ways)

vesicles hold/release neurotransmitters

• autoreceptors - if sense too many neurotransmitters, will tell vesicles to stop sending more

• reuptake - transporting neurotransmitters back into cell

• degrading enzymes - release enzymes that break down neurotransmitters

synaptic cleft

gap where neurotransmitters are released from axon terminal

presynaptic cell vs post synaptic cell

presynaptic - send signal

post synapatic - receive signal

neurotransmitter

chemical messengers that neurons use to communicate each other

• affect behavior/thoughts

• lock/key mechanism w receptors

myelin sheath

fatty substance that wraps around axon

• myelination - speeds up transmission keeping signal strong

• saltatory conduction - signal jumps, only get action potentials when there is no myelin,

  • fewer action potentials = speeds up transmission

neural plasticity

describes nervous systems ability to change over time

• nervous system is continually changing when we learned/injured

brain changes in 4 primary ways

1. growth of dendrites and axons

2. synaptogenesis - formation of new synapses

3. pruning - death of certain neurons and retraction of axons to remove connections that aren’t useful

   • brain can process info efficiently w fewer neurons

4. myelination - insulation of axons w a myelin sheath

central nervous system

controls mind and behavior, brain and spinal cord

peripheral nervous system

helps us remain in constant state, regular body temp, blood pressure

1. somatic nervous system (SNS)

2. autonomic nervous system (ANS)

   • sympathetic NS

   • parasympathetic NS

somatic nervous system (SNS)

part of peripheral nervous system PNS

• external environment, skeletal muscles

• afferent nerves - signals arrive to CNS (brain) from skeletal muscles

• efferent nerves - signals exit CNS (brain) to skeletal nerves

autonomic nervous system (ANS)

part of the PNS

• internal environment, internal organs, lung liver heart

• afferent nerves - signals arrive to CNS from internal organs

• efferent nerves- signals exit CNS to internal organs

2 divisions

• sympathetic NS

  • adrenal glands

  • arousal, mobilize energy resources

  • fight or flight

• parasympathetic NS

  • calming, conserve energe

  • rest or digest

spinal cord

conveys info btwn brain and rest of body, superhighway

• controls reflexes

nerves

projections of neurons to and from other body parts

how reflexes work (spinal cord)

reflexes- autonomic motor responses to sensory stimuli

1. spinal cord contains sensory neurons that connect with interneurons

• interneurons - connect sensory nerves with motor nerves within spinal cord without having to report back to brain

3 major brain structures

forebrain, midbrain, hindbrain

forebrain

controls complex cognitive, emotional, sensory, motor function

• divided into

  • cerebral cortex : 5 lobes

  • subcortical structures: 3 structures

cerebral cortex

responsible for most complex aspects of perception, emotion, movement and thought

frontal lobe

abstract thinking, movement, planning, memory/judgement

• motor cortex- voluntary movement

• broca’s area - language generation

temporal lobe

part of cerebral cortex

hearing and language

• primary auditory cortex

  • wernicke’s area - language comprehension

parietal lobe

part of cerebral cortex

touch

• somatosensory cortex

occiptal lobe

part of cerebral cortex

visual info

• visual cortex

insular lobe

part of cerebral cortex

taste perception, perceives internal organ states

• linked to compassion/empathy

subcortical structures

part of forebrain

3 structures: basal ganglia, limbic system, pituitary gland

basal ganglia

subcortical structure

intentional movements

• works w motor cortex, controls posture/movement

limbic system

subcortical structure

• where subcortical structure meets cortex

• four F’s - feed, fight, flee, fuck

• 4 parts: hippocampus, amygdala, thalamus, hypothalamus

hippocampus

part of limbic system

creates new memories

amygdala

part of limbic system

emotional process/memories

• fear

thalamus

part of limbic system

• relay/filter info from senses into cerebral cortex

hypothalamus

regulate body temp, hunger, thirst, sexual behavior

pituitary gland

part of subcortical structure

• master gland, hormone producing system

  • hormone direct functions of many other glands

Midbrain

orientation/movement

• track sensory stimuli

hindbrain

coordinates info coming in/out of spinal cord

• 4 parts: reticular information, medulla, cerebellum, pons

reticular formation

part of hindbrain

• regulation of sleep, arousal

  • damage = coma

medulla

part of hindbrain

extension of spinal cord - heart rate, circulation, respiration

• damage = die

cerebellum

part of hindbrain

• fine motor skills

• little brain, largest structure of hindbrain

  • play piano

pons

part of hindbrain

• bridge

• relay info from cerebellum to rest of brain

  • sleep/dream

contralateral control

opposite hemisphere controls opposite side of the body

lateralized function

left = fine tune lang skill speech

right = coarse lang skill, visuospatial skills action

corpus callosum

connect let and right hemisphere

• part of forebrain, cerebral cortex

split brain patients

corpus callosum is slashed = visual info originating from left field can’t be processed in right hemisphere

endocrine system

network of glands that releases hormones into bloodstream

diff btwn hormones and neurotransmitters

hormones are transmitted through blood vessels rather than nerves

oxycotin

pituitary hormone, reproductive functions

• maternal/romantic love

  • influence how much we trust others, social behavior

adrenal glands

emergency center

• makes adrenaline and cortisol

part of sympathetic nervous system

adrenaline

hormone that allows ppl to perform amazing feats in crisis

cortisol

adrenal hormone that increases in response to physical and psychological stressors

• regulates blood pressure/cardiovascular function

sexual reproductive glands

testes - males

ovaries - females

testosterone

male hormone that inc sex drive

estrogen

female hormone, regulates human reproductive system

EEG (electroencephalograph)

measures electrical activity generated by brain

• infer whether person awake/asleep, which region active

• place on scalp → noninvasive, so frequently used

• schizophrenics, epilepsy

• tells little abt whats happening inside individ brain cells/regions

  • better at telling when not where in brain

CT (computed tomography)

3d reconstruction of multiple x rays taken through a part of the body

• visualize brain structure

  • neuroimaging

MRI (magnetic resonance imaging)

measure release of energy from water in biological tissues following exposure to magnetic field

• better than CT for detecting soft tissues like brain tumor

PET (position emission tomography)

functional imaging technique that measures changes in brain activity in response to stimuli

• inject radioactive glucose to see which brain region active → invasive

fMRI (functional MRI)

standard technique in functional brain imaging research

• measure changes in blood oxygen level

MEG (magnetoencephalography)

detects electrical activity in brain by measuring tiny magnetic fields in milliseconds

how misinterpret brain imaging techniques

misunderstand how they work

• functional brain images is not photos of brain activity

  • subtract brain activity in control task from experimental task

• dont allow us to make definite diagnose of mental disorder

chromosomes

contains strands of DNA that carry genetic information

• inside cell’s nucleus

• humans have 46 chromosomes

  • females have YY

  • males have XY

genes

sections of DNA that contain genetic material

• codes for everything (eye, hair, height)

DNA

shaped like double helix that stores everything cells need to replicate themselves

allele

one of two or more alternative forms of a gene

homozygous

when two alleles of a gene in a specific pair are the same

EE homozygous dominant

ee homozygous recessive

heterozygous

when two alleles of a gene in the specific pair are different

dominant

attributes are expressed in heterozygous pairr

recessive

attributes are masked in the heterozygous pair

geneotype

persons genetic makeup

• inherited from parents

phenotype

set of observable traits

• shaped by environment

monogenic inheritance

trait determined by one pair of genes

• rare

polygenic inheritance

trait determined by combo of more than one pair of genes

heritability

extent to which genes contribute to differences in a trait among individuals

• 0.0 - genes do not contribute at all to phenotypic individual differences

• 1.0 - genes are the only reason for inindividual differences

studying heritability (3 ways)

family studies, twin studies, adoption studies

family studies

study heritability

• examine extent to which characteristic runs or goes together in families

• estimate risk of disorder among relatives

• don’t share similar environment

  • doesn’t allow us to separate effects of nature from nurture

twin studies

study heritability

• compares resemblance of identical and fraternal twins w respect to a trait

• twins share common environment

• identical = 100% shared genes = monozygotic

• fraternal = 50% shared genes = dizygotic

if identical twins more alike on psychological traits (ex. intelligence )than fraternal twins, can infer trait is genetically influenced

adoption studies

study heritability

• examine extent to which children adopted into new homes resemble biological parents compared to adoptive parents

  • deals w being unable to separate genetic from environmental influences

5 misconceptions of heritability

1. heritability applies to single individual rather than diff among individ

2. heritability tells whether trait can be changed by environmental factors

   • environmental changes can impact everyone in population, changes trait not heritability

   • reaction range: extent to which your genes set limits to how much a trait can change in a new environment

     • eye color - limited, IQ bigger

3. heritability is a fixed number

   • refers to influence of genes compared to environments on individual differences in trait/behavior in given population in given time

4. effects of gene (heritability) are the same for everyone across whole population

   1. different heritability in IQ btwn rich and poor

5. heritability implies destiny, high heritability for behavioral problem implies that only hope would be to alter genes

gene x environment interactions

• phenotypic effect - determined by the interaction btwn the environment and organism’s genetic makeup

• genetic differences may only be apparent in specific environments

• studies: depression, maze dull/maze bright

depression study

gene x environment study

• why do some ppl who face stressful life events develop depression while others don’t

• gene for serotonin reuptake protein can have long/short allele

  • L/L L/s s/s

• those with short allele exhibit more symptoms of depression when exposed to stressful situations