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Exam 3
Adv. Cellular Neuroscience
198
Other
Graduate
11/19/2019

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Term
what is the "instructive signal for learning"?
Definition
reward prediction error
Term
what does dopamine affect in ADHD?
Definition
focus
Term
what does dopamine affect in Parkinson's Disease?
Definition
movement
Term
depression results from disruption of the ______ system
Definition
dopamine
Term
how is dopamine changed in schizophrenia?
Definition
elevated levels
Term
OCD is a disorder associated with dysfunction of the ______ system
Definition
dopamine
Term
number one mechanism of addiction is that it hijacks the ______ system
Definition
dopamine
Term
Tourette's Syndrome ticks result from issues with ______
Definition
dopamine
Term
what neurotransmitter has cell bodies that express tyrosine hydroxylase (TH)?
Definition
dopamine
Term
3 steps to make dopamine
Definition
tyrosine --> (via tyrosine hydroxylase) --> L-Dopa --> (via aromatic L-amino acid decarboxylase (AAD)) --> dopamine
Term
2 places dopamine is found
Definition
1. VTA
2. SNc
Term
do many neurons synthesize dopamine?
Definition
no! (but it does a ton of things in the brain)
Term
2 dopamine pathways in the brain
Definition
1. mesocorticolimbic
2. nigrostriatal
Term
VTA = ______ dopamine neurons projections
Definition
motivation/reward
Term
SNc = ______ associated dopamine neurons projections
Definition
movement
Term
what determines how dopamine is going to affect the cell?
Definition
the type of receptor that the neuron expresses!
Term
difference between D1 & D2 metabotropic dopamine receptors
Definition
D1: Gs-coupled receptors

D2: Gi-coupled receptors
Term
D1 type dopamine receptors ______ activity of target cells
Definition
increase
Term
D2 type dopamine receptors ______ activity of a neuron
Definition
decrease
Term
is it possible for some cells to express both kinds of dopamine receptors?
Definition
yes!
Term
metabotropic receptors
Definition
means that they don't themselves open & allow ions to flow across the membrane but instead are coupled to intracellular signaling cascades
Term
GPCRs (G-protein coupled receptors) are examples of _____ receptors
Definition
metabotropic
Term
GPCRs have ______ transmembrane domains
Definition
7
Term
3 subunits in trimeric G-proteins
Definition
1. alpha
2. beta
3. gamma
Term
largest & most diverse group of receptors in eukaryotes
Definition
GPCRs
Term
job of GPCRs
Definition
inform the cell about its environment
Term
what is the evolutionarily conserved process by which extracellular signals are converted to intracellular signals for the cell once a GPCR is activated?
Definition
upon activation, alpha subunit converts uses GTP & dissociates from receptor --> alpha & gamma subunit go to their thing (can be separate!)
Term
one of the ultimate target molecules of G-alpha signaling
Definition
PKA
Term
one of the ultimate target molecules of G-beta/gamma signaling
Definition
GRK channels
Term
can different parts of G-protein have different functions within the cell?
Definition
yes
Term
why do about 1/3-1/2 of all marketed drugs target some type of GPCR?
Definition
they can greatly amplify/prolong an extracellular signal in an intracellular cascade
Term
3 main types of G-alpha subunits (very important to whether a GPCR will increase or decrease neural activity)
Definition
1. G-alpha-S (Gs)
2. G-alpha-i (Gi)
3. G-alpha-q (Gq)
Term
adenylate cyclase
Definition
an enzyme that sits in the lipid bilayer; its job = make cAMP
Term
PLC
Definition
an enzyme that sits in the membrane; when activated, increases activity of small molecules (ex. IP3, DAG)
Term
D1 type dopamine receptors coupled to Gs proteins --> _____ when binds to dopamine
Definition
increase cAMP activity
Term
D2 type dopamine receptors coupled to Gi proteins --> decrease cAMP activity when binds to dopamine --> ______ neural activity
Definition
decrease
Term
why can dopamine be involved in so many functions in the brain?
Definition
there are various pathways & within a pathway various kinds of receptors for dopamine
Term
______ is central to the formation of operant memories
Definition
dopamine!
Term
is the dopamine signal rewarding or aversive?
Definition
very rewarding
Term
how do you demonstrate that dopamine is necessary & sufficient for learning the operant task?
Definition
"necessary" test: no dopamine --> no learning

"sufficient" test: all you need is dopamine --> learning
Term
initial phase of monkey/juice reward experiment
Definition
monkey sits in chair & stares at screen --> when it sees a rewarded symbol he licks a spout to get a juice reward --> record from neurons in the VTA (extracellular recordings so you see on the read-out little tick marks when APs from dopamine neurons happen) --> there are a lot more spikes right after the monkey gets the juice reward
Term
graph showing tick marks when APs happen within a neuron across various trials
Definition
Raster plot
Term
sum of the APs at a certain time point on a Raster plot
Definition
Peristimulus Time Histogram (PSTH)
Term
second phase of monkey/juice reward experiment
Definition
dopamine bursts when first juice is delivered --> monkey will start paying attention to what happens just before they get the juice --> dopamine will increase when it learns that purple star means juice is coming --> a lot of learning, dopamine will increase at star & not juice!
Term
describe a Raster Plot
Definition
x axis = time

y axis = trial

marks demonstrate neuron spikes
Term
classic Raster Plot example
Definition
monkey learning that purple star cue indicates a later juice reward delivery
Term
phasic burst (or phasic firing) of dopamine neurons
Definition
high frequency firing
Term
tonic firing of dopamine neurons
Definition
regular (baseline) firing rates
Term
2 places VTA dopamine neurons target
Definition
1. NAc
2. prefrontal cortex
Term
what does each row in a Raster plot represent?
Definition
one trial
Term
when does phasic dopamine neuron firing occur in first few presentations of juice reward US?
Definition
with the unexpected juice reward --> monkey starts paying attention to things that may cue the reward
Term
when does phasic dopamine neuron firing occur after many trials where purple star is a CS for the juice?
Definition
phasic firing of dopamine neurons gets transferred from the juice to the star
Term
what happens to dopamine neuron firing if the monkey sees the purple star but no juice is given?
Definition
there will be a pause in dopamine neuron firing
Term
the difference between what reward you were expecting & what reward you experienced
Definition
reward prediction error (encoded by dopamine neurons)
Term
VTA projects dopaminergic neurons --> ?
Definition
NAc
Term
SNc projects dopaminergic neurons --> ?
Definition
striatum
Term
how does potentiation happen in the NAc?
Definition
recording from a NAc neuron that has AMPARs --> stimulate prefrontal cortex that synapses onto it at the same time as dopamine neuron from VTA is synapsing onto that neuron --> those synapses will be potentiated (as opposed to separate synapses that are associated with other actions)
Term
how does a surprise reward affect dopamine response?
Definition
big!
Term
how does dopamine firing look with a completely expected reward?
Definition
dopamine burst at cue that makes you expect reward but not when reward is given
Term
formula for reward prediction error
Definition
reward prediction error = actual reward - predicted reward
Term
error signals encoded by the dopamine signal is what drives _______
Definition
learning
Term
what disease can be thought of as essentially extreme reward learning?
Definition
addiction
Term
what does the "compulsive" nature of addiction mean?
Definition
you can't stop even though you know it's bad
Term
2 dissociable aspects of addictive process
Definition
1. learn cues & contexts that predict the availability of drugs
2. once learned, cues motivate drug seeking
Term
large loops across brain area get affected in addiction --> this information eventually gets consolidated into the _______ ("habit center")
Definition
dorsal striatum
Term
the center of the limbic system & addiction circuitry
Definition
NAc
Term
links rewards to actions/contexts/objects via its various inputs
Definition
NAc
Term
provides motivation behind actions & ascribes rewards to certain behaviors
Definition
NAc
Term
drugs of abuse = increase particularly the _______ firing of dopamine neurons
Definition
phasic
Term
how do actions get manipulated in addiction?
Definition
teaches the brain which actions were present at the time that the rewarding event occurred & will encourage the brain to seek out those actions in the future
Term
_______ provides a teaching signal that teaches you which actions to do to get a reward
Definition
dopamine
Term
mechanism by which cocaine increases dopamine
Definition
increase release of dopamine from terminals (VTA --> NAc synapse); increase concentration of dopamine in synaptic cleft
Term
mechanism by which methamphetamines increase dopamine
Definition
increase release of dopamine from terminals (VTA --> NAc synapse); increase concentration of dopamine in synaptic cleft
Term
mechanism by which nicotine increases dopamine
Definition
activates nicotinic ACh receptors on VTA dopamine neurons --> increase firing rate of dopamine neurons --> increase the amount of dopamine being released
Term
mechanism by which opioids increase dopamine
Definition
activate Gi-coupled receptors (especially mu-opioid receptors) on GABAergic interneurons --> decrease activity of inhibitory interneurons in VTA --> disinhibit VTA dopamine neurons
Term
cocaine = blocks ______
Definition
dopamine transporter (DAT)
Term
methamphetamine affect on DAT & VMAT
Definition
reverses DAT

inhibits VMAT
Term
what protein is involved in packaging dopamine into vesicles
Definition
VMAT
Term
dopamine neurons in the VTA get ______ inputs that provide information about context when they should spike
Definition
glutamatergic
Term
conclusion from Ungless paper
Definition
a single exposure to cocaine (when paired with glutamatergic input activity) drives LTP at the glutamatergic synapse on dopamine neurons via the learning mechanisms we discussed previously (NMDAR --> calcium --> insertion of more AMPARs)
Term
Ungless figure 1: after cocaine exposure --> _______ in AMPA-mediated currents at VTA synapses
Definition
increase
Term
Ungless figure 5: occlusion experiment - did LTP happen in vivo?
Definition
can induce significantly more LTP in saline animals than cocaine

can induce significantly more LTD in cocaine animals than saline
Term
does LTD happen pre- or post-synaptically?
Definition
either
Term
how does LTD help learning?
Definition
some parts of the brain "learn" by eliminating synapses!
Term
the process by which synapses are removed (often during development) that are not required for efficient information transfer
Definition
synaptic pruning
Term
a particular form of LTD that occurs in the cerebellum
Definition
motor learning
Term
brain area that mediates motor learning
Definition
cerebellum
Term
how is the cerebellum different from the cortex/hippocampus in how it operates on learning rules?
Definition
cortex/hippocampus = learning by gaining synapses

cerebellum = learning by eliminating synapses
Term
cerebellum provides _______ adaptive control of movement
Definition
feedforward
Term
main cells in cerebellum
Definition
Purkinje cells (extremely complex dendritic branching from cell body)
Term
Purkinje cell dendrites = source of input from ______
Definition
parallel fibers of granule cells
Term
does a single Purkinje cell have a lot or a few synapses?
Definition
millions of different synapses & can integrate information about many different aspects from the sensory world
Term
can Purkinje cells self-generate action potentials?
Definition
yes
Term
parallel fibers = what kind of neuron?
Definition
glutamatergic --> glutamate onto Purkinje AMPARs & mGluR1 (metabotropic glutamate receptor)
Term
climbing fibers from inferior olive in brainstem --> input to ______
Definition
Purkinje cells
Term
anatomical compartmentalization for synapses
Definition
dendritic spines
Term
how do spine synapses in cerebellum respond to error signal?
Definition
when error signal arrives, the neuron weakens spine synapses that were active during the depolarization from the climbing fiber
Term
spaces between the spines where there is no glutamatergic input for Purkinje cells
Definition
dendritic shaft
Term
climbing fibers synapse all over the shaft --> make entire Purkinje cell super _______
Definition
depolarized
Term
climbing fibers activate ______
Definition
voltage-gated calcium channels --> influx of calcium --> plasticity
Term
if you just stimulate parallel fibers --> what affect on Purkinje?
Definition
activates the AMPARs in the spine
Term
can you get plasticity by just stimulating parallel fibers onto Purkinje?
Definition
no!
Term
coincident activation between parallel & climbing fibers onto Purkinje
Definition
calcium comes in when glutamate is being released by parallel fibers --> removal of those specific AMPARs
Term
do climbing fiber synapses change on Purkinje?
Definition
no!
Term
presynaptic terminal of parallel fiber --> what kind of input onto Purkinje?
Definition
glutamate release onto AMPARs & mGluR1 in spine
Term
climbing fiber input onto Purkinje --> what comes into the neuron?
Definition
calcium coming in (kind of in between spine & shaft)
Term
what affect does PKC have on cerebellar AMPARs?
Definition
PKC phosphorylates AMPARs --> internalized --> LTD at that synapse
Term
2 things that need to happen for PKC to be activated in Purkinje
Definition
1. mGluR1 are activated
2. a big calcium signal from climbing fiber input
Term
9 steps in cerebellar LTD
Definition
1. parallel fiber glutamate
2. binds to mGluR1
3. Gq subunit released intracellularly (is activated)
4. activates phospholipase C
5. phospholipase C cleaves PIP2 into DAG & IP3
6. IP3 increases intracellular calcium
7. activation of PKC (AS LONG AS voltage-gated calcium from climbing fiber is also present
8. phosphorylates AMPARs
9. AMPARs are interalized
Term
symptoms of Parkinson's Disease
Definition
slowed movement, rigidity, tremor (specifically resting tremor), shuffling gate, stooped posture, blank expression
Term
second most common neurodegenerative disease (behind Alzheimer's)
Definition
Parkinson's Disease
Term
why is Parkinson's Disease characterized as a movement disorder?
Definition
main symptom: bradykinesia (slowed movements) or trouble initiating movements
Term
does Parkinson's Disease have cognitive symptoms?
Definition
yes! despite being known as a mood disorder
Term
does Parkinson's Disease have autonomic symptom problems?
Definition
yes!
Term
Parkinson's Disease is a disorder of the _______ system
Definition
nigrostriatal
Term
what can you see in control brains that you can't see in PD brains?
Definition
a black pigment at the SNc (produced by the dopaminergic neurons here)
Term
striatum = input nucleus of ______
Definition
BG
Term
SNc = home of dopamine neurons that project to the ________
Definition
striatum
Term
2 output nuclei of BG
Definition
1. SNr (substantia nigra reticulata)
2. GPi (globus pallidus internal segment)
Term
BG affects movement by regulating _______
Definition
corticothalamic loop
Term
what does the striatum do when the cortex feeds it with all possible motor commands?
Definition
filters out motor commands that should be done & motor commands that shouldn't be done
Term
two types of striatal neurons (called "medium spiny neurons" or MSNs)
Definition
1. direct pathway: D1-receptor expressing GABAergic neurons
2. indirect pathway: D2-receptor expressing GABAergic neurons
Term
increase in activity of direct pathway D1 MSNs --> ?
Definition
decrease activity of output nuclei --> disinhibition of thalamus --> movement
Term
how does indirect pathway affect motor control?
Definition
suppresses motor commands that you do not want to do
Term
increase of D2 activity --> ?
Definition
increase in basal ganglia output --> decreases movement
Term
PD comes from _______
Definition
overactive indirect pathway activity --> "break" on movement is too hard
Term
cause of Parkinson's Disease
Definition
death of SNc dopamine neurons
Term
direct = D1 MSNs --> what effect on movement?
Definition
inhibitory onto SNr/GPi --> disinhibition of thalamocortical loop --> facilitates movement
Term
indirect = D2 MSNs --> what effect on movement?
Definition
inhibitory onto GPe --> disinhibition of STN --> excitatory onto SNr/GPi --> inhibition of thalamocortical loop --> suppresses movement
Term
two classes of GABAergic neurons in striatum
Definition
1. D1-receptor-expressing MSNs
2. D2-receptor-expressing MSNs
Term
what kind of receptors are D1 & D2 in striatum?
Definition
metabotropic receptors coupled to G proteins in the cell
Term
under normal conditions, striatum is bathed in dopamine from ______
Definition
SNc neurons
Term
D1 is coupled to ______ G proteins
Definition
Gs
Term
D2 is coupled to ______ G proteins
Definition
Gi
Term
when dopamine is around, how does it act through the D1 or D2 neurons to affect neuronal activity?
Definition
naturally boosts D1 MSNs

naturally decreases D2 MSNs
Term
MSN input from cortex is ______
Definition
glutamatergic
Term
what can D2 MSNs do that D1 cannot?
Definition
send retrograde signal back to pre-synaptic glutamatergic cortical neuron to normally tamper the amount of input it gets
Term
main idea of PD symptoms: loss of LTD onto _______
Definition
D2 MSNs
Term
stimulation of cortical inputs --> LTD of D2 MSNs only under what conditions?
Definition
in the presence of dopamine!!
Term
7 steps in LTD of glutamatergic-D2 MSN synapse
Definition
1. presynaptic neuron = glutamatergic input from cortex
2. mGluR5s on D2 MSNs coupled to Gq G proteins
3. cleaves precursors of retrograde messengers
4. bind Cb1 (cannabinoid) receptor in presynaptic terminal
5. these receptors are coupled to Gi
6. decrease calcium
7. decrease possibility of neurotransmitter release
Term
endogenous ligands of cannabinoid receptors
Definition
endocannabinoids
Term
exogenous ligands of cannabinoid receptors
Definition
cannabis (marijuana)
Term
EPSCs measured in D2 MSN dendrite in striatum come from
Definition
AMPA/NMDA
Term
5 steps of making retrograde messenger in D2 MSN
Definition
1. glutamate
2. mGluR5
3. Gq
4. activate PLC (phospholipase C) IF dopamine is also present via the D2 receptors
5. generation of endocannabinoids which retrograde message to the presynaptic neuron
Term
11 steps in breakdown of PLC cascade for LTD in D2 MSN
Definition
1. PLC
2. cleaves PIP2 (phospholipid found in cell membrane)
3. results in IP3 & DAG (diacylglycerol)
4. DAG gets converted into endocannabinoids (ECBs) via DAG lipase
5. retrograde messenger
6. ECBs bind to Cb1 receptors
7. coupled to Gi
8. decreases voltage-gated calcium channels
9. less calcium in presynaptic terminal
10. less glutamate release
11. LTD!
Term
why does coincidence detection only happen in D2 & not D1 to activate the PLC?
Definition
D2-coupled receptors have Gi (D1 has Gs) which is necessary for the cascade that activates PLC!
Term
D2 MSNs pre-LTD = paired pulse _______
Definition
facilitation
Term
D2 MSNs post LTD = paired pulse _____
Definition
facilitation BUT first pulse is smaller than original pre-LTD pulse (tells you LTD got induced ) & second pulse is smaller than original pre-LTD second pulse
Term
why do you do paired pulse experiments?
Definition
gives you insights into release probability of presynaptic terminal
Term
equation for PPR (paired pulse ratio)
Definition
PPR = EPSC 2/EPSC 1
Term
what is the current dopamine replacement therapy for PD
Definition
Levodopa
Term
PD cause
Definition
death of SNc dopamine neurons
Term
problem of using dopamine replacement to treat PD
Definition
giving the patient dopamine is not specific for the SNc --> striatum pathway!
Term
2 limitations of DBS to treat PD
Definition
1. highly effective while stimulation is on, but symptoms return as soon as stimulation is turned off
2. masks symptoms but does not repair underlying brain dysfunction
Term
before DBS, what was done as a PD treatment?
Definition
GPi/SNr was cut out!
Term
how does DBS work to treat PD?
Definition
input stimulating electrode into either subthalamic nucleus or GPi
Term
2 challenges for current PD therapies
Definition
1. not ideal for long-term care because they lose efficacy and/or cause side effects over time
2. new strategies must be developed to repair, not simply mask, brain dysfunction in PD
Term
main opportunity coming from basic research for PD therapies
Definition
new insights into which neural circuits are the best to target to maximize therapeutic benefit while minimizing side effects
Term
why can't you get specificity with DBS in striatum?
Definition
D1 & D2 cells are all intermingled
Term
rhodopsin
Definition
a protein in our eyes that converts light energy into neuronal signals
Term
channelrhodopsin
Definition
a protein found in algae that converts light energy into neural signals
Term
what is the benefit of having neurons express ChR2?
Definition
can be controlled with light pulses
Term
optogenetics
Definition
a technology that renders neurons genetically sensitive to light
Term
difficulty with optogenetics
Definition
need wavelengths that can penetrate deep into tissue (or even through the skull to be non-invasive!)
Term
how do you send light in optogenetic experiments?
Definition
fiberoptic cables chronically implanted
Term
benefit of optogenetic experiments
Definition
can do them in freely moving animals to observe how it affects behavior!
Term
how do you get channelrhodopsin into neurons?
Definition
viral transfection
Term
channelrhodopsin (ChR2)
Definition
cation channel; used to excite neurons
Term
halorhodopsin (NpHR)
Definition
neuronal silencer
Term
bacteriorhodopsin & archaerhodopsin (Arch)
Definition
neuronal silencer
Term
what is the process where you use synthesized ligands to affect either channel or metabotropic receptor action?
Definition
chemogenetics
Term
what is the process of inducing an ion channel that is not normally expressed in a mammalian cell that is activated by different wavelengths of light?
Definition
optogenetics
Term
3 types of optogenetics channels
Definition
1. ChR2
2. NpHR
3. Arch
Term
what process works on the same properties as optogenetics but gates via ligands instead of light?
Definition
chemogenetics
Term
in the dopamine-depleted state (Parkinsonian), there is an imbalance in _______
Definition
direct/indirect pathway activity
Term
activating D1 pathways makes you ______
Definition
go
Term
activating D2 neurons makes you ______
Definition
stop
Term
when ChR2 is expressed in D1 (direct pathway) --> ?
Definition
increase in ambulation
Term
When ChR2 is expressed in D2 (indirect pathway) --> ?
Definition
decrease in ambulation
Term
what was the big empirical study of the paper we presented?
Definition
first empirical evidence of direct "go" vs indirect "no go" dichotomy
Term
how to make a mouse model of PD
Definition
lesion via 6-OHDA
Term
goal to treat PD in the paper we presented
Definition
increase activity in D1 MSNs --> restore ambulation in the PD mouse model to levels like pre-lesion!
Term
what does it mean that PD is caused by specific dopamine neuron loss?
Definition
SNc dopamine neurons die; VTA dopamine neurons do not
Term
why can't you get cell-type specificity with just stimulating electrode of DBS?
Definition
direct & indirect pathway neurons are all right next to each other
Term
limitations of L-DOPA to treat PD
Definition
patients can only tolerate it for a few years & then side effects become worse than the disease itself
Term
limitations of DBS to treat PD
Definition
very intense surgery & only works when stimulator is on
Term
overactivation of D2 --> ? onto GPe
Definition
higher inhibition
Term
why would stimulating GPe theoretically rescue movement in PD?
Definition
in PD, GPe is getting overly inhibited so this should help relieve it
Term
what was the result with global GPe stimulation in PD?
Definition
immobility did not go away during GPe stimulation
Term
does the GPe contain different types of neurons?
Definition
yes
Term
stimulating GPe PV neurons --> ? in PD
Definition
long-lasting rescue of motor movement in PD mouse model
Term
why does cell-specific stim of GPe work to relieve PD but global stim doesn't?
Definition
non-PV neurons (Lhx6) interfere or block the therapeutic effects of PV stimulation
Term
put Arch in Lhx6 neurons --> ? in PD
Definition
motor rescue!
Term
what does it mean that there is a scaling problem in translating optogenetics into humans?
Definition
injecting a virus into the mouse brain --> you can use the tiniest amount of a virus but it won't spread enough to be really effective in human brain
Term
how are researchers trying to get around the problem of light delivery into the brain to use optogenetics in humans?
Definition
shifting opsins to be responsive to far-red --> can shine light of that wavelength actually through the skull
Term
why is optogenetics so helpful as a research tool?
Definition
find out which circuits we need to target & use human-relevant therapeutics to target those circuits
Term
why would conventional DBS in GPe not work to treat PD?
Definition
we would be stimulating all GPe neurons --> no net effect
Term
What change to DBS in GPe made it work in relieving PD symptoms?
Definition
changing DBS to be brief stimulations
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