LTP and LTD

Question 1

synaptic plasticity

Answer 1

ability of synapses to strengthen or weaken over time. It is a history dependent change in synaptic transmission.

Question 2

ways of distinguishing plasticity

Answer 2

potentiation/depression
time course (short/long)

Question 3

where does synaptic plasticity occur

Answer 3

all regions of the brain (&SC)

Question 4

how can synaptic transmission be measured

Answer 4

brain slices
in vivo

Question 5

what induces synaptic plasticity

Answer 5

high/low frequency stimulation

Question 6

different forms of synaptic plasticity

Answer 6

STP - over time dissipates
LTP - remains elevated, higher frequency
LTD

Question 7

examples of short term plasticity

Answer 7

paired-pulse facilitation (PPF) pre synaptic plasticity

post-tetanic potentiation (PTP)

Question 8

LTP duration

Answer 8

very long lasting (1 year recording)

Question 9

Hebb’s postulate

Answer 9

when an axon of cell A excites a cell B axon and repeatedly takes part in firing, some growth processes or metabolic changes take place in one or both cells so that A’s efficiency as one of the cells firing B is increased.

Question 10

properties of LTP

Answer 10

-input specific (LTP only at synapses)

-cooperativity (many axons needed to pass threshold)

-associativity (little stimulation at same time can cause LTP)

Question 11

what does an increase in synaptic transmission cause

Answer 11

increased conductivity of AMPAR
increased density of AMPAR
more synaptic vesicle release

Question 12

what does LTP induction require

Answer 12

NMDAR (coincidence detector)
postsynaptic depolarisation

Question 13

steps in LTP induction

Answer 13

glutamate opens NMDA channel
Ca-CaM activates kinases
phosphorylates AMPAr
more Na+ entry
more receptors

Question 14

what type of signalling occurs in LTP induction

Answer 14

retrograde signalling
gases (NO)
act pre synaptically so more NT release

Question 15

what occurs after LTP induction

Answer 15

immediate structural changes,
input specific change

Question 16

role of CaMKII

Answer 16

trafficking and phosphorylation of AMPAR

Question 17

where does CaMKII autophosphorylation occur

Answer 17

Thr 286
inhibits CaM activity

Question 18

role of CaMKII activity reporter

Answer 18

2 flurophores: dimVenus/mEGF
colour code fluorscence
high activity = warm colours

Question 19

what does CaMKII activity occulude

Answer 19

LTP induction

Question 20

what is CamKII autophosphorylation required for

Answer 20

CA1-LTP

not for DG-LTP

Question 21

what are silent synapses

Answer 21

functional NMDA receptors
no AMPA receptors

Question 22

what occurs in the developing hippocampus

Answer 22

silent synapses and LTP induction

Question 23

how to obtain late-LTP

Answer 23

gene transcription and protein synthesis induction and multiple tetani in brain slices

Question 24

what gene is transcribed after synaptic stimulation

Answer 24

c-fos (immediately early gene)

Question 25

role of synaptic tagging/synaptic culture

Answer 25

enables input specificity and a type of associativity tag setting -> PRP capture ->L-LTP

Question 26

how is experimental evidence collected for synaptic tagging

Answer 26

using a protein synthesis blocker

Question 27

role of PKMzeta in LTP maintenance

Answer 27

prevents endocytosis of AMPAR and phosphorylates synapses PIN1 - inhibitor of own mRNA translation

Question 28

role of ZIP (zeta inhibitory peptide)

Answer 28

erases LTP after consolidation but is not specific

Question 29

different types of LTP

Answer 29

brain region (CA1/DG) age (juvenile/adult/aged) stimulation frequency (E-LTP/L-LTP)

Question 30

what does LTD stand for

Answer 30

long term depression

Question 31

what does LTD stimulation cause

Answer 31

dephosphorylation and endocytosis low frequency NMDAR activation

Question 32

age dependence of LTD induction

Answer 32

NMDAR subunits change with age. NR2B containing NMDARs are more permeable to calcium and is more abundant in post natal development.

Question 33

2 types of LTD in CA1

Answer 33

NMDAR-LTD (low ca2+, phosphatases) mGluR-LTD (activates PKC, phosphorylates AMPAR)

Question 34

what is spike timing dependent plasticity (STDP)

Answer 34

timing of presynaptic & postsynaptic firing determines whether LTD/LTP induced, or whether synaptic transmission does not change

Question 35

LTD in cerebellum

Answer 35

parallel fibres from granule cell mossy fibre climbing fibre purkinje cell output is inhibitory neurons

Question 36

LTD at parallel fibre-purkinje cell synapses

Answer 36

long lasting input specific cooperativity (threshold stimulation needed) coinciding input at parallel fibre & climbing fibre synapses

Question 37

role of pf-PC LTD

Answer 37

important for cerebellar learning