L8 - action potentials Flashcards
golgi staining
only stain some neurons
what did golgi think about the NS compared to Cajal
golgi thought the NS was continuous
Cajal correctly identiified the NS as individual ‘contigious’ neurons and saw they were connected by axons
describe the monosynaptic stretch reflex
specialised ending/muscle spindle sends signal down sensory nerve Glutamate neurotransmitter released spinal cord AMPA receptor ACh released signal down motor nerve nicotinic receptor muscle contraction
hippocampus is involved in
learning
memory
spatial navigation
hippocampus means
seahorse
how do you make hippocampal recordings
in vitro - slices
in vivo - implant electrodes
ipsilateral neurons
same side of brain
contralateral neurons
other side of brain
how do CA1 pyr neurons talk to both ipsilateral and contralateral neurons
via axons
terminal bouton
specialised pre-synaptic terminal at end of axon
what allows APs to propagate everywhere and activates all synapses
APs clone themselves and split at branches
think tree diagram
synaptic vesicles
balls of lipid membrane
antiporter
transports neurotransmitter into vesicle via proton
e.g. H+ exchange antiporter
role of SNARE proteins
mediate vesicle fusion with target membrane-bound compartment
where is v-SNARE found
on vesicle
where is t-SNARE found
on pre-synaptic plasma membrane
3 proteins that make up SNARE complex
SNAP-25 and syntaxin on t-SNARE
Synaptobrevin on v-SNARE
overall mechanism of botox
targets synapses that release ACh and interferes with SNARE proteins
synaptotagmin
protein in vesicle membrane
important for dockin
Ca2+ binding domains
probability of release (Pr)
APs do not always trigger release of neurotransmitter
Pr ranges from
0-1
effect of Pr on synaptic strength
if Pr increases then synaptic strength increases
Pr = 0
no synaptic communication
equation for calculating average Pr of population
no of synapses that are active on each trial / no of synapses in total population
what is a good pr estimate
if a pair is connected by 1 synapse
how do you change Pr
alter pre-synaptic Ca2+ entry
e.g. blockers
short term synaptic plasticity
short lived change in strength of synaptic coupling that reflects on prior activity of the synapse
what is a mossy fibre
a class of axon
what makes up the trisynaptic loop
perforant path (PP)
mossy fibre pathway (MFP)
Schaffer-collateral commissural pathway (SCCP)
synapses with low Pr
exhibit Paired Pulse Faciliation (PPF)
synapses with high Pr
exhibit Paired pulse depression (PPD)
PPF
Paired Pulse Facilitation
when post synaptic potentials following arrival of an impulse are increased due to that following a prior impulse
a form of short-term synaptic plasticity
PPD
paired pulse depression
form of short term synaptic plasticity
when the second post synaptic potential decreases
what is the effect of reducing Ca2+ on Pr and PPD
reducing Ca2+ reduces Pr
therefore eliminates PPD
