L11 - synaptic plasticity

Question 1

what mediates post synaptic response

Answer 1

receptor opening

Question 2

why are dendrites and dendritic spines important

Answer 2

functional compartmentalisation

Question 3

functional compartmentalisation

Answer 3

impacts synaptic plasticity

‘neck’ on spines restricts ionic or biochemical changes to the just activated synapse

Question 4

PSD: Post Synaptic density

Answer 4

electron-dense region at the membrane of a post-synaptic neuron
made up of core and pallium

Question 5

what are the proteins in the PSD for

Answer 5

they anchor and regulate the neurotransmitter receptors

Question 6

L-Glutamate

Answer 6

excitatory amino acid neurotransmitter

Question 7

synthesis of glutamate

Answer 7

made from glutamine

via glutaminase enzyme

Question 8

1952 - hyashi experiment

Answer 8

injected glutamate into dogs –> seizures caused

Question 9

vGLUT

Answer 9

transports cytosolic glutamate into vesicles

Question 10

why do neurotransmitters need to be removed from synapse

Answer 10

so system can rest

Question 11

what removes glutamate from synapse

Answer 11

glu transporters on pre and post membranes

astrocytes

Question 12

what are AMPA receptors permeable to

Answer 12

Na+

K+

Question 13

what are NMDA receptors permeable to

Answer 13

Na+
Ca2+ (permeable pore)
K+

(Mg2+ block)

Question 14

AMPA and NMDA both tetrameric - what does thsi mean?

Answer 14

4 independent subunits with a hole in the middle

Question 15

at what voltage does is NMDA blocked by Mg2+

Answer 15

-80mV

Question 16

effect of depolarisation NMDA receptor

Answer 16

-35mV
Mg2+ block removed
Ca2+ influx into post-synaptic spine

Question 17

features of NMDA receptors

Answer 17

mediate slow-rising, long-lasting EPSPs

Question 18

define synaptic plasticity

Answer 18

the ability to change the strength of synaptic connections and consolidate new pathways in teh CNS

Question 19

what is LTP

Answer 19

long term potentiation

Long-lasting increase in synaptic signal transmission
persisten strengthening of synapses

Question 20

what is long term depression

Answer 20

reduction in efficacy of synapses

Question 21

types of GABA receptors

Answer 21

GABAa - ionotropic

GABAb - metabotropic

Question 22

features of GABAa receptors

Answer 22

ligand-gated ion channel
rapid channel opening 
pentameric 
Cl- influx down conc. grad.
causes hyperpolarisation 
synaptic inhibition

Question 23

features of GABAb receptors

Answer 23

GPCR
7 transmembrane
mediates long, slow bit of IPSP

Question 24

what is VGAT

Answer 24

transporter that uptakes GABA into vesicles to terminate neurotransmitter action

Question 25

why do you get a long extra sag in IPSP

Answer 25

co-activation of GABAa and GABAb receptors

Question 26

mechanism of GABAb receptors once GABA has bound

Answer 26

Beta and gamma subunits break off and activate K+ channels

alpha subunit activates Gi/o signalling- inhibits cAMP

Question 27

affect of pre-synaptic Ca2+ channels on probability of release

Answer 27

if Ca2+ channels on pre-synaptic terminal are closed, e.g. due to GABA receptors activated
probability of release will decrease

Question 28

if 2 identical pre-synaptic stimuli are given in rapid succession..

Answer 28

then the 2nd IPSP is smaller