Synaptic Integration

Question 1

The _____ measures how far the PSP will spread from the synapse

Answer 1

“length constant”

Question 2

The PSP diminishes with _____ distance from the

synapse

Answer 2

increasing

Question 3

For a shorter length constant (smaller λ): the synapses must be spaced ___ together to enable effective spatial summation between them

Answer 3

closer

Question 4

For a longer length constant (higher λ): the synapses can be spaced further apart and there will still be _____ spatial summation between them

Answer 4

effective

Question 5

_____ occurs through the summation of repetitive postsynaptic responses occurring at multiple synapses along the neuronal membrane

Answer 5

“synaptic integration”

Question 6

When there is an increasing depolarization, the frequency is _____.

Answer 6

Also increasing

Question 7

When action potential is firing and there is an increase in IPSPs; it will ___ the membrane potential going to axon hillock.

Answer 7

Drop

Question 8

_____ input is due to Axosomatic (inhibitory) located closer to the cell body, and Axodendritic (excitatory) further away.

Answer 8

Inhibitory

Question 9

Recurrent feedback is via an ___ interneuron

Answer 9

Inhibitory

Question 10

Feedforward pathway is via _____.

Answer 10

Excitatory

Question 11

Synaptic integration has ___ inputs, of a ___ nature, to ___ neuron.

Answer 11

multiple; multiple; one

Question 12

Networks of interconnected neurons using combinations of feedforward and feedback excitatory and inhibitory synaptic relays. This is known as?

Answer 12

Neural integration

Question 13

What is synaptic integration?

Answer 13

the process through which multiple synaptic responses are “summed together” to determine whether or not the postsynaptic neuron responds by firing action potentials

Question 14

a given neuron will typically receive 100’s to 1000’s of?

Answer 14

Individual synaptic inputs

Question 15

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

Answer 15

False

It will NOT be strong enough!

Question 16

to cause a neuron to start “firing” action potentials, ____ excitatory inputs must ____ ____ to cause a sufficient level of depolarization at the axon hillock …

Answer 16

multiple; sum together

Question 17

Name the two general strategies that cobmine to raise the membrane potential of the postsynaptic neuron to the threshold of its axon hillock region:

Answer 17

1) Temporal summation

2) Spatial summation

Question 18

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

Answer 18

Temporal summation

Question 19

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

Answer 19

Spatial summation

Question 20

The normal input to any one given synapse will consist of a ____ of action potentials

Answer 20

Train

Question 21

Upon the arrival of any one action potential, the duration of the postsynaptic potential is dependent upon?

Answer 21

• 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

Question 22

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.

Answer 22

False; the period of time between action potentials must be SHORTER

Question 23

for a given frequency of arriving impulses, the effectiveness of temporal summation will depend upon the ____ of the PSP

Answer 23

Duration

Question 24

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)

Answer 24

A) less effective summation (a higher frequency of stimulation is therefore required to enable summation)

Question 25

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)

Answer 25

B) more effective summation (a lower frequency of stimulation will still enable summation)

Question 26

The duration of a single PSP is measured by the postsynaptic membrane’s ____ ____

Answer 26

time constant

Question 27

What is time constant?

Answer 27

reflects how rapidly the postsynaptic membrane depolarizes, and then repolarizes, in response to the arrival of one action potential at the presynaptic nerve ending

Question 28

At any particular synapse, the postsynaptic time constant is determined from its overall ____

Answer 28

structure

Question 29

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

Answer 29

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

Question 30

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

Answer 30

B) a greater duration of the postsynaptic EPSP or IPSP, allowing for effective summation of impulses that arrive at a lower frequency

Question 31

What is spatial summation?

Answer 31

occurs when simultaneously occurring postsynaptic responses from multiple synapses sum together

Question 32

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

Answer 32

spread away; electrotonic conduction

Question 33

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)

Answer 33

B) less effective summation (the synapses be spaced closer together to enable summation)

Question 34

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)

Answer 34

A) more effective summation (the synapses may be spaced further apart and summation will still occur)