Term
what is the "instructive signal for learning"? |
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Definition
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Term
what does dopamine affect in ADHD? |
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Definition
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Term
what does dopamine affect in Parkinson's Disease? |
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Definition
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Term
depression results from disruption of the ______ system |
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Definition
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Term
how is dopamine changed in schizophrenia? |
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Definition
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Term
OCD is a disorder associated with dysfunction of the ______ system |
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Definition
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Term
number one mechanism of addiction is that it hijacks the ______ system |
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Definition
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Term
Tourette's Syndrome ticks result from issues with ______ |
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Definition
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Term
what neurotransmitter has cell bodies that express tyrosine hydroxylase (TH)? |
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Definition
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Term
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Definition
tyrosine --> (via tyrosine hydroxylase) --> L-Dopa --> (via aromatic L-amino acid decarboxylase (AAD)) --> dopamine |
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Term
2 places dopamine is found |
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Definition
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|
Term
do many neurons synthesize dopamine? |
|
Definition
no! (but it does a ton of things in the brain) |
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Term
2 dopamine pathways in the brain |
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Definition
1. mesocorticolimbic 2. nigrostriatal |
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Term
VTA = ______ dopamine neurons projections |
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Definition
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Term
SNc = ______ associated dopamine neurons projections |
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Definition
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Term
what determines how dopamine is going to affect the cell? |
|
Definition
the type of receptor that the neuron expresses! |
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Term
difference between D1 & D2 metabotropic dopamine receptors |
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Definition
D1: Gs-coupled receptors
D2: Gi-coupled receptors |
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Term
D1 type dopamine receptors ______ activity of target cells |
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Definition
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Term
D2 type dopamine receptors ______ activity of a neuron |
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Definition
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Term
is it possible for some cells to express both kinds of dopamine receptors? |
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Definition
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Term
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Definition
means that they don't themselves open & allow ions to flow across the membrane but instead are coupled to intracellular signaling cascades |
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Term
GPCRs (G-protein coupled receptors) are examples of _____ receptors |
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Definition
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Term
GPCRs have ______ transmembrane domains |
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Definition
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Term
3 subunits in trimeric G-proteins |
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Definition
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Term
largest & most diverse group of receptors in eukaryotes |
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Definition
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Term
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Definition
inform the cell about its environment |
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Term
what is the evolutionarily conserved process by which extracellular signals are converted to intracellular signals for the cell once a GPCR is activated? |
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Definition
upon activation, alpha subunit converts uses GTP & dissociates from receptor --> alpha & gamma subunit go to their thing (can be separate!) |
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Term
one of the ultimate target molecules of G-alpha signaling |
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Definition
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Term
one of the ultimate target molecules of G-beta/gamma signaling |
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Definition
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Term
can different parts of G-protein have different functions within the cell? |
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Definition
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Term
why do about 1/3-1/2 of all marketed drugs target some type of GPCR? |
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Definition
they can greatly amplify/prolong an extracellular signal in an intracellular cascade |
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Term
3 main types of G-alpha subunits (very important to whether a GPCR will increase or decrease neural activity) |
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Definition
1. G-alpha-S (Gs) 2. G-alpha-i (Gi) 3. G-alpha-q (Gq) |
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Term
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Definition
an enzyme that sits in the lipid bilayer; its job = make cAMP |
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Term
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Definition
an enzyme that sits in the membrane; when activated, increases activity of small molecules (ex. IP3, DAG) |
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Term
D1 type dopamine receptors coupled to Gs proteins --> _____ when binds to dopamine |
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Definition
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|
Term
D2 type dopamine receptors coupled to Gi proteins --> decrease cAMP activity when binds to dopamine --> ______ neural activity |
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Definition
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|
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 |
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Term
______ is central to the formation of operant memories |
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Definition
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|
Term
is the dopamine signal rewarding or aversive? |
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Definition
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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 |
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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 |
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Term
graph showing tick marks when APs happen within a neuron across various trials |
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Definition
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Term
sum of the APs at a certain time point on a Raster plot |
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Definition
Peristimulus Time Histogram (PSTH) |
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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! |
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Term
|
Definition
x axis = time
y axis = trial
marks demonstrate neuron spikes |
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Term
classic Raster Plot example |
|
Definition
monkey learning that purple star cue indicates a later juice reward delivery |
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Term
phasic burst (or phasic firing) of dopamine neurons |
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Definition
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|
Term
tonic firing of dopamine neurons |
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Definition
regular (baseline) firing rates |
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Term
2 places VTA dopamine neurons target |
|
Definition
1. NAc 2. prefrontal cortex |
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|
Term
what does each row in a Raster plot represent? |
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Definition
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|
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 |
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|
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 |
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|
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 |
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|
Term
the difference between what reward you were expecting & what reward you experienced |
|
Definition
reward prediction error (encoded by dopamine neurons) |
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|
Term
VTA projects dopaminergic neurons --> ? |
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Definition
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|
Term
SNc projects dopaminergic neurons --> ? |
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Definition
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|
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) |
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|
Term
how does a surprise reward affect dopamine response? |
|
Definition
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|
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 |
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|
Term
formula for reward prediction error |
|
Definition
reward prediction error = actual reward - predicted reward |
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|
Term
error signals encoded by the dopamine signal is what drives _______ |
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Definition
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|
Term
what disease can be thought of as essentially extreme reward learning? |
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Definition
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|
Term
what does the "compulsive" nature of addiction mean? |
|
Definition
you can't stop even though you know it's bad |
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|
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 |
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Term
large loops across brain area get affected in addiction --> this information eventually gets consolidated into the _______ ("habit center") |
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Definition
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|
Term
the center of the limbic system & addiction circuitry |
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Definition
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|
Term
links rewards to actions/contexts/objects via its various inputs |
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Definition
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|
Term
provides motivation behind actions & ascribes rewards to certain behaviors |
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Definition
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|
Term
drugs of abuse = increase particularly the _______ firing of dopamine neurons |
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Definition
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|
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 |
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|
Term
_______ provides a teaching signal that teaches you which actions to do to get a reward |
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Definition
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|
Term
mechanism by which cocaine increases dopamine |
|
Definition
increase release of dopamine from terminals (VTA --> NAc synapse); increase concentration of dopamine in synaptic cleft |
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|
Term
mechanism by which methamphetamines increase dopamine |
|
Definition
increase release of dopamine from terminals (VTA --> NAc synapse); increase concentration of dopamine in synaptic cleft |
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|
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 |
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|
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 |
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|
Term
|
Definition
dopamine transporter (DAT) |
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|
Term
methamphetamine affect on DAT & VMAT |
|
Definition
reverses DAT
inhibits VMAT |
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|
Term
what protein is involved in packaging dopamine into vesicles |
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Definition
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|
Term
dopamine neurons in the VTA get ______ inputs that provide information about context when they should spike |
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Definition
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|
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) |
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|
Term
Ungless figure 1: after cocaine exposure --> _______ in AMPA-mediated currents at VTA synapses |
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Definition
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|
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 |
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|
Term
does LTD happen pre- or post-synaptically? |
|
Definition
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|
Term
how does LTD help learning? |
|
Definition
some parts of the brain "learn" by eliminating synapses! |
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|
Term
the process by which synapses are removed (often during development) that are not required for efficient information transfer |
|
Definition
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|
Term
a particular form of LTD that occurs in the cerebellum |
|
Definition
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|
Term
brain area that mediates motor learning |
|
Definition
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|
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 |
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|
Term
cerebellum provides _______ adaptive control of movement |
|
Definition
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|
Term
|
Definition
Purkinje cells (extremely complex dendritic branching from cell body) |
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|
Term
Purkinje cell dendrites = source of input from ______ |
|
Definition
parallel fibers of granule cells |
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|
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 |
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|
Term
can Purkinje cells self-generate action potentials? |
|
Definition
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|
Term
parallel fibers = what kind of neuron? |
|
Definition
glutamatergic --> glutamate onto Purkinje AMPARs & mGluR1 (metabotropic glutamate receptor) |
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|
Term
climbing fibers from inferior olive in brainstem --> input to ______ |
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Definition
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|
Term
anatomical compartmentalization for synapses |
|
Definition
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|
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 |
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|
Term
spaces between the spines where there is no glutamatergic input for Purkinje cells |
|
Definition
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|
Term
climbing fibers synapse all over the shaft --> make entire Purkinje cell super _______ |
|
Definition
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|
Term
climbing fibers activate ______ |
|
Definition
voltage-gated calcium channels --> influx of calcium --> plasticity |
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|
Term
if you just stimulate parallel fibers --> what affect on Purkinje? |
|
Definition
activates the AMPARs in the spine |
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|
Term
can you get plasticity by just stimulating parallel fibers onto Purkinje? |
|
Definition
|
|
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 |
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|
Term
do climbing fiber synapses change on Purkinje? |
|
Definition
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|
Term
presynaptic terminal of parallel fiber --> what kind of input onto Purkinje? |
|
Definition
glutamate release onto AMPARs & mGluR1 in spine |
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|
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 |
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|
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 |
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|
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 |
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|
Term
symptoms of Parkinson's Disease |
|
Definition
slowed movement, rigidity, tremor (specifically resting tremor), shuffling gate, stooped posture, blank expression |
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|
Term
second most common neurodegenerative disease (behind Alzheimer's) |
|
Definition
|
|
Term
why is Parkinson's Disease characterized as a movement disorder? |
|
Definition
main symptom: bradykinesia (slowed movements) or trouble initiating movements |
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|
Term
does Parkinson's Disease have cognitive symptoms? |
|
Definition
yes! despite being known as a mood disorder |
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|
Term
does Parkinson's Disease have autonomic symptom problems? |
|
Definition
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|
Term
Parkinson's Disease is a disorder of the _______ system |
|
Definition
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|
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) |
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|
Term
striatum = input nucleus of ______ |
|
Definition
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|
Term
SNc = home of dopamine neurons that project to the ________ |
|
Definition
|
|
Term
|
Definition
1. SNr (substantia nigra reticulata) 2. GPi (globus pallidus internal segment) |
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|
Term
BG affects movement by regulating _______ |
|
Definition
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|
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 |
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|
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 |
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|
Term
increase in activity of direct pathway D1 MSNs --> ? |
|
Definition
decrease activity of output nuclei --> disinhibition of thalamus --> movement |
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|
Term
how does indirect pathway affect motor control? |
|
Definition
suppresses motor commands that you do not want to do |
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|
Term
increase of D2 activity --> ? |
|
Definition
increase in basal ganglia output --> decreases movement |
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|
Term
|
Definition
overactive indirect pathway activity --> "break" on movement is too hard |
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|
Term
cause of Parkinson's Disease |
|
Definition
death of SNc dopamine neurons |
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|
Term
direct = D1 MSNs --> what effect on movement? |
|
Definition
inhibitory onto SNr/GPi --> disinhibition of thalamocortical loop --> facilitates movement |
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|
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 |
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|
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
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|
Term
D1 is coupled to ______ G proteins |
|
Definition
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|
Term
D2 is coupled to ______ G proteins |
|
Definition
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|
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 |
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|
Term
MSN input from cortex is ______ |
|
Definition
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|
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 |
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|
Term
main idea of PD symptoms: loss of LTD onto _______ |
|
Definition
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|
Term
stimulation of cortical inputs --> LTD of D2 MSNs only under what conditions? |
|
Definition
in the presence of dopamine!! |
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|
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 |
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|
Term
endogenous ligands of cannabinoid receptors |
|
Definition
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|
Term
exogenous ligands of cannabinoid receptors |
|
Definition
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|
Term
EPSCs measured in D2 MSN dendrite in striatum come from |
|
Definition
|
|
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 |
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|
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! |
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|
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! |
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|
Term
D2 MSNs pre-LTD = paired pulse _______ |
|
Definition
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|
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
|
|
Term
what is the current dopamine replacement therapy for PD |
|
Definition
|
|
Term
|
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
|
|
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
|
Definition
a protein in our eyes that converts light energy into neuronal signals |
|
|
Term
|
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
|
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
|
|
Term
|
Definition
cation channel; used to excite neurons |
|
|
Term
|
Definition
|
|
Term
bacteriorhodopsin & archaerhodopsin (Arch) |
|
Definition
|
|
Term
what is the process where you use synthesized ligands to affect either channel or metabotropic receptor action? |
|
Definition
|
|
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
|
|
Term
3 types of optogenetics channels |
|
Definition
|
|
Term
what process works on the same properties as optogenetics but gates via ligands instead of light? |
|
Definition
|
|
Term
in the dopamine-depleted state (Parkinsonian), there is an imbalance in _______ |
|
Definition
direct/indirect pathway activity |
|
|
Term
activating D1 pathways makes you ______ |
|
Definition
|
|
Term
activating D2 neurons makes you ______ |
|
Definition
|
|
Term
when ChR2 is expressed in D1 (direct pathway) --> ? |
|
Definition
|
|
Term
When ChR2 is expressed in D2 (indirect pathway) --> ? |
|
Definition
|
|
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
|
|
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
|
|
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
|
|
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
|
|
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? |
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Definition
find out which circuits we need to target & use human-relevant therapeutics to target those circuits |
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Term
why would conventional DBS in GPe not work to treat PD? |
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Definition
we would be stimulating all GPe neurons --> no net effect |
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Term
What change to DBS in GPe made it work in relieving PD symptoms? |
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Definition
changing DBS to be brief stimulations |
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