Synaptic Integration Flashcards
The _____ measures how far the PSP will spread from the synapse
“length constant”
The PSP diminishes with _____ distance from the
synapse
increasing
For a shorter length constant (smaller λ): the synapses must be spaced ___ together to enable effective spatial summation between them
closer
For a longer length constant (higher λ): the synapses can be spaced further apart and there will still be _____ spatial summation between them
effective
_____ occurs through the summation of repetitive postsynaptic responses occurring at multiple synapses along the neuronal membrane
“synaptic integration”
When there is an increasing depolarization, the frequency is _____.
Also increasing
When action potential is firing and there is an increase in IPSPs; it will ___ the membrane potential going to axon hillock.
Drop
_____ input is due to Axosomatic (inhibitory) located closer to the cell body, and Axodendritic (excitatory) further away.
Inhibitory
Recurrent feedback is via an ___ interneuron
Inhibitory
Feedforward pathway is via _____.
Excitatory
Synaptic integration has ___ inputs, of a ___ nature, to ___ neuron.
multiple; multiple; one
Networks of interconnected neurons using combinations of feedforward and feedback excitatory and inhibitory synaptic relays. This is known as?
Neural integration
What is synaptic integration?
the process through which multiple synaptic responses are “summed together” to determine whether or not the postsynaptic neuron responds by firing action potentials
a given neuron will typically receive 100’s to 1000’s of?
Individual synaptic inputs
T/F:
a depolarizing ionic current across a single synapse will be strong enough to drive a spread of current along the inner membrane of the neuron to depolarize its axon hillock above its threshold for triggering an action potential
False
It will NOT be strong enough!
to cause a neuron to start “firing” action potentials, ____ excitatory inputs must ____ ____ to cause a sufficient level of depolarization at the axon hillock …
multiple; sum together
Name the two general strategies that cobmine to raise the membrane potential of the postsynaptic neuron to the threshold of its axon hillock region:
1) Temporal summation
2) Spatial summation
Of the two strategies which one is below?
sum the individual EPSP’s generated by a train of action potentials arriving at one particular synapse
Temporal summation
Of the two strategies which one is below?
sum the individual EPSP’s that are generated at multiple synapses due to inputs that all arrive nearly simultaneously
Spatial summation
The normal input to any one given synapse will consist of a ____ of action potentials
Train
Upon the arrival of any one action potential, the duration of the postsynaptic potential is dependent upon?
- the rate of degradation and/or removal of the neurotransmitter from the synaptic cleft
- and, how rapidly ion pumps operate along the postsynaptic membrane to restore its resting Vm
T/F:
To enable effective temporal summation the period of time between successive action potentials must be longer than the duration of the individual PSP’s.
False; the period of time between action potentials must be SHORTER
for a given frequency of arriving impulses, the effectiveness of temporal summation will depend upon the ____ of the PSP
Duration
If the duration is short:
A) less effective summation (a higher frequency of stimulation is therefore required to enable summation)
B) more effective summation (a lower frequency of stimulation will still enable summation)
A) less effective summation (a higher frequency of stimulation is therefore required to enable summation)
If the duration is prolonged:
A) less effective summation (a higher frequency of stimulation is therefore required to enable summation)
B) more effective summation (a lower frequency of stimulation will still enable summation)
B) more effective summation (a lower frequency of stimulation will still enable summation)
The duration of a single PSP is measured by the postsynaptic membrane’s ____ ____
time constant
What is time constant?
reflects how rapidly the postsynaptic membrane depolarizes, and then repolarizes, in response to the arrival of one action potential at the presynaptic nerve ending
At any particular synapse, the postsynaptic time constant is determined from its overall ____
structure
A shorter time constant implies?
A) that the duration of the postsynaptic EPSP or IPSP is less arriving impulses will have to be spaced closer together (higher frequency) to enable effective summation
B) a greater duration of the postsynaptic EPSP or IPSP, allowing for effective summation of impulses that arrive at a lower frequency
A) that the duration of the postsynaptic EPSP or IPSP is less arriving impulses will have to be spaced closer together (higher frequency) to enable effective summation
A longer time constant implies?
A) that the duration of the postsynaptic EPSP or IPSP is less arriving impulses will have to be spaced closer together (higher frequency) to enable effective summation
B) a greater duration of the postsynaptic EPSP or IPSP, allowing for effective summation of impulses that arrive at a lower frequency
B) a greater duration of the postsynaptic EPSP or IPSP, allowing for effective summation of impulses that arrive at a lower frequency
What is spatial summation?
occurs when simultaneously occurring postsynaptic responses from multiple synapses sum together
For a given spacing between synapses, the effectiveness of spatial summation will depend upon how far the PSP will ____ ____ from each synapse by ____ ____along the inside membrane
spread away; electrotonic conduction
Less spread of PSP?
A) more effective summation (the synapses may be spaced further apart and summation will still occur)
B) less effective summation (the synapses be spaced closer together to enable summation)
B) less effective summation (the synapses be spaced closer together to enable summation)
More spread of PSP?
A) more effective summation (the synapses may be spaced further apart and summation will still occur)
B) less effective summation (the synapses be spaced closer together to enable summation)
A) more effective summation (the synapses may be spaced further apart and summation will still occur)
