L11 - synaptic plasticity Flashcards
what mediates post synaptic response
receptor opening
why are dendrites and dendritic spines important
functional compartmentalisation
functional compartmentalisation
impacts synaptic plasticity
‘neck’ on spines restricts ionic or biochemical changes to the just activated synapse
PSD: Post Synaptic density
electron-dense region at the membrane of a post-synaptic neuron
made up of core and pallium
what are the proteins in the PSD for
they anchor and regulate the neurotransmitter receptors
L-Glutamate
excitatory amino acid neurotransmitter
synthesis of glutamate
made from glutamine
via glutaminase enzyme
1952 - hyashi experiment
injected glutamate into dogs –> seizures caused
vGLUT
transports cytosolic glutamate into vesicles
why do neurotransmitters need to be removed from synapse
so system can rest
what removes glutamate from synapse
glu transporters on pre and post membranes
astrocytes
what are AMPA receptors permeable to
Na+
K+
what are NMDA receptors permeable to
Na+
Ca2+ (permeable pore)
K+
(Mg2+ block)
AMPA and NMDA both tetrameric - what does thsi mean?
4 independent subunits with a hole in the middle
at what voltage does is NMDA blocked by Mg2+
-80mV
effect of depolarisation NMDA receptor
-35mV
Mg2+ block removed
Ca2+ influx into post-synaptic spine
features of NMDA receptors
mediate slow-rising, long-lasting EPSPs
define synaptic plasticity
the ability to change the strength of synaptic connections and consolidate new pathways in teh CNS
what is LTP
long term potentiation
Long-lasting increase in synaptic signal transmission
persisten strengthening of synapses
what is long term depression
reduction in efficacy of synapses
types of GABA receptors
GABAa - ionotropic
GABAb - metabotropic
features of GABAa receptors
ligand-gated ion channel rapid channel opening pentameric Cl- influx down conc. grad. causes hyperpolarisation synaptic inhibition
features of GABAb receptors
GPCR
7 transmembrane
mediates long, slow bit of IPSP
what is VGAT
transporter that uptakes GABA into vesicles to terminate neurotransmitter action
why do you get a long extra sag in IPSP
co-activation of GABAa and GABAb receptors
mechanism of GABAb receptors once GABA has bound
Beta and gamma subunits break off and activate K+ channels
alpha subunit activates Gi/o signalling- inhibits cAMP
affect of pre-synaptic Ca2+ channels on probability of release
if Ca2+ channels on pre-synaptic terminal are closed, e.g. due to GABA receptors activated
probability of release will decrease
if 2 identical pre-synaptic stimuli are given in rapid succession..
then the 2nd IPSP is smaller
