Flashcards
Seminar 1 - Introduction to Synaptic Physiology
Cards in this deck (54)
- 1what are the 3 pillars of neurophysiology?1) intrinsic excitability
2) synaptic function
3) network behaviours - 2what does an axon do?'talking'
- 3dendrite?listening
- 4how many neurons and synapses are in the human CNS?100 billion neurons
100 trillion synapses - 52 types of synapses?chemical (most common) --> NT mediated
electrical --> gap junction mediated - 6which of GABAa-c are GPCR?GABAb
- 7what is PSD?post synaptic density
darker area --> tells you where the receptors are expressed on the membrane/ where the synapse is - 8imaging spines problems?only tells you the location and not the function
not able to quantify the strength of each synapse
only shows one dendrite --> doesn't show the complex network and other connections
doesn't identify the specific synaptic strengthening when someone learns something - 9what affects release probability?dynamic and changed by the frequency with which the synapses are activated, iconic conditions, temperature, activation of presynaptic
- 10why may an AP not cause NT release?maybe not enough vesicles/docked vesicles
probability renders Ca2+ channels closed - 11how to carry out in vitro and in vivo hippocampal recordings?in vitro - electrophysiological recordings on hippocampal slices
in vivo - electronic diode placed on head and placed on hippocampus - 12where is the human hippocampus situated?sits at the base of the temporal lobe --> one either side
fornix carries info out of the other areas
information from the cortex comes into the dentate gyrus (DG) - 13trisynaptic loop?
- 14what is the perforant pathway?axons of the cortical cells coming into the hippocampus
forms synapses with the DG cells (granule cells) - 15what is the MFP?mossy fibre pathway
granule cell axons synapse with cells in the CA3 (pyramidal cells) - 16what is the schaffer collateral commissural pathway?studied the most
CA3 --> CA1 (pyramidal neurons)
then sends information to the cortex and other brain regions - 17what is the TAP?tempero- ammonic pathway
cortex --> CA1 - 18what is the ACP?associational commissural pathway
CA3 pyramidal cells synapse on other CA3 cells on both the same and opposite side of the brain - 19what is synaptic plasticity?a change in the strength of functional coupling between discrete neuronal structures ( or neuron-effector ( gland/heart) systems)
EVERY TIME A SYNAPSE IS ACTIVATED IT EXHIBITS PLASTICITY - 20what is the time course for synaptic plasticity?
- 21pathological plasticity?changed wiring in neuropathic pain/ epilepsy
- 22regenerative plasticity?rewiring after the trauma
- 23what is the plasticity protocol?use a test stimulus and a conditioning stimulus
first, need to work out the baseline response --> stimulate and calculate synaptic response --> roughly the same
stimulate at the SAME RATE --> frequency and intensity is always the same - 24homosynaptic plasticity?when the plasticity occurs at the synapses you have conditioned
only conditioned synapses express plasticity - 25heterosynaptic plasticity?conditioned and some non-conditioned synapses express plasticity
- 26other?chemical plasticity
chemicals that induce plasticity --> not every specific - 27why does plasticity happen?memory
sensory (chronic pain, vision, olfaction, touch)
effector system (NMJ)
addiction/ reward
network computation
network maintenance
pathologies - 28what presynaptic changes to synaptic function can arise??changes in Ca2+ ion channel density function
changes in NT storage --> more/ less vesicles
more/fewer vesicles released
changes in membrane potential - 29postsynaptic?receptor density ( +/- AMPA-Rs)
receptor sensitivity
in/decreased receptor efficiency (increased conductancy or probability of opening)
changes to spine/active zone number
changes in ionic gradients (Cl- and K+) - 30trans-synaptic?changes in removal of NT
change distance between synapses
changes in extracellular pH
changes in physiological properties of synaptic cleft - 31how is long term synaptic plasticity induced in vivo?appropriate intrinsic presynaptic firing patterns
neuronal synchrony - 32induce LTP?100Hz
- 33induce LTD?1Hz x 900
- 34what is electrophysiology?recording electrical changes that occur from ions moving across a lipid membrane
- 35Nernst equation?
- 36what is the reseting neuronal membrane most permeable to?potassium ions as it is closest to Ek
- 37how are signals in the NS encoded?voltage fluctuations
- 38what does the current clamp do?records the membrane potential of the cell --> currents is constant and voltage change is recorded
neuron is allowed to do what it wants (depolarise and hyperpolarise)
can inject current to depolarise or hyper polarise
records what the cell does under physiological conditions - 39voltage clamp?experimenter controls (clamps) the membrane voltage
the amount of current required to maintain the cells at a given voltage is measured - 40what type of preparations? in order of easiest first?1) dissociated neuronal cultures
2) organotypic brain slices
3) acute brain slices
4) whole animal - 41how do mEPSPs occur?occur spontaneously in the absence of AP firing
channels spontaneously open and may allow Ca2+ in and cause NT release. Or a vesicle may spontaneously fuse with the presynaptic membrane - 42what are sEPSCs?spontaneous synaptic transmission occurring as a result of spontaneous presynaptic action potentials
- 43what is quantal analysis?n = no. active synapses
p = probability of release
q = potency of neurotransmitter - 44in terms of quantal analysis, a change in mEPSP frequency and amplitude means what?change in mEPSP frequency = suggests a change in P or N
change in mEPSP amplitude = suggests a change in Q - 45what is minimal stimulation?stimulating at a very low level that causes APs to fire in one fibre and transmitter only to be released from one synapse
- 46what is minimal stimulation used for?a way of measuring the probability of release
if 5 stimulations only gets 1 response
Pr= 0.2
assumption = stimulation always evokes an action potential (Pap = 1) - 47what does DHPG induce?increased failures --> form of chemical synaptic plasticity
- 48what is a disadvantage of whole cell patch clamp?space clamp
neuron is very large and notable to clamp its voltage properly
not able to clamp voltage precisely enough
errors from large fast currents - 49techniques to get around this limitation?dendritic patch clamp --> very difficult because dendrite is small (3cm)--> record synaptic currents much closer to the synapse
patches to record fractions of large fast currents
using outside-out patches to study AMPA-R currents - 50give an example of a presynaptic recording from a giant bouton?Calyx of held - auditory pathway from ears to the brainstem
need to record from terminals directly to understand them well --> size is a problem - 51what is real time imaging?important neurophysiological method for studying neuronal function
- 52how is this done?Ca sensitive fluorescent dyes or proteins introduced into neurons to enable the monitoring of synaptic activity
Ca is important in producing both long and short-term plasticity
equipment is way more expensive than electrophysiology - 53what will a Ca dye report?1) ca entry that triggers NT release in presynaptic vesicles
2) ca entry into postsynaptic elements that have been activated
3) action potential firing (as APs drive ca entry) - 54give an example of a genetically encoded Ca indicatorGCaMP6
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- 3rd Year Synaptic Plasticity Flashcards on Seminar 1 - Introduction to Synaptic Physiology, created by William Chapman on 28/04/2017.
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