When the neuron has a short time constant. Only EPSPs that arrive near simultaneously will summate.
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What is a rate coding neuron?
When the time constant is longer precise timing of EPSPs is less important and activity is determined by average rate of EPSPs.
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What happens at an inhibitory synapse?
Hyperpolarisation due to net outflow of positive charges.
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What happens when excitatory and inhibitory synapses fire on different dendrites at some distance from the soma?
Linear summation of currents at the soma.
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What happens when there is an inhibitory synapse between the excitatory synapse and the soma on the same dendrite?
The current flow from the inhibitory synapse counteracts that of the excitatory synapse. The opening of ion channels by the inhibitory synapse lowers Rm changing the length constant affecting the spread of the EPSP. Non linear summation.
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What happens if the synaptic reversal potential equals the resting membrane potential?
Neurotransmitter binds to receptor, opening on ion channels, change in Rm but no current flow and no change in membrane potential.
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What is the problem with studying complex synaptic integration?
Neurons form multiple contact sites with each other, just stimulating one neuron activates multiple synaptic sites.
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What are the main experimental approaches to study synaptic integration?
Computational models and photolysis of caged neurotransmitters.
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How does photolysis of caged neurotransmitters work?
Brain slice bathed in inactive NT. Exposure to UV light releases NT. Neuron is filled with fluorescent dye to visualise process. UV light focussed on small spots and briefly turned on. Releases small amounts of glutamate and mimics synaptic release.
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When is soma depolarisation in terms of summation strongest?
When synapses are activated from the furthest away to the closest in order.
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Why is summation only linear when synapses are on different dendrites?
Changes in membrane resistance do not affect the spread of the EPSP or IPSP.
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What is "silent" postsynaptic inhibition?
Inhibitory synapses can affect EPSPs, even if they do not cause a change in membrane potential.
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Other cards in this set
Card 2
Front
What is a rate coding neuron?
Back
When the time constant is longer precise timing of EPSPs is less important and activity is determined by average rate of EPSPs.
Card 3
Front
What happens at an inhibitory synapse?
Back
Card 4
Front
What happens when excitatory and inhibitory synapses fire on different dendrites at some distance from the soma?
Back
Card 5
Front
What happens when there is an inhibitory synapse between the excitatory synapse and the soma on the same dendrite?
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