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Control of Calcium Influx. (A): f as a function of time after presynaptic spiking. Presynaptic input is required for f to be nonzero. (B): H as a function of synaptic voltage. The magnitude of H increases with depolarized voltages, peaking around 10 mV.

To regulate postsynaptic voltage, we use a Back-propagating Action Potential (BPAP), which increases whenever the postsynaptic cell fires. The BPAP represents the postsynaptic cell's feedback, indicative of how recently the postsynaptic cell has spiked. The magnitude of the BPAP is dependent on the following equation:

B P A P ( t ) = 100 ( I f b e - t / τ f b + I s b e - t / τ s b )

Similar to f , the decay of the BPAP is regulated by a fast and a slow component. Upon a postsynaptic spike the BPAP causes the voltage to reach a maximum of 100 mV above the resting potential. We allow a delay of 2 ms between postsynaptic firing and the delivery of the BPAP to the dendrites. The fast component has time constant τ f b = 3 ms and the slow component has time constant τ s b = 25 ms. I f b and I s b are also chosen such that they add up to one: here, we use I f b = 0.75 and I s b = 0.25. Note that whenever a cell fires, the BPAP is sent through all dendrites, increasing the voltage at all of its presynaptic connections. In this plasticity model, the BPAP provides postsynaptic feedback and drives calcium influx, which allows for the potentiation of synaptic weights. Along with the function f , the BPAP ensures Calcium dependence on both pre and postsynaptic spike times.

Calcium Influx Parameters
Parameter Value Description
τ C a 50 ms Calcium influx decay constant
g N - 1 × 10 - 3 μ M/(ms mV) NMDAR conductance
I f f 0.7 Proportion of fast decay of f
I s f 0.3 Proportion of slow decay of f
τ f f 50 ms f fast decay time constant
τ s f 200 ms f slow decay time constant
V C a 130 mV Calcium Reversal Potential
I f b 0.75 Proportion of fast BPAP decay
I s b 0.25 Proportion of slow BPAP decay
τ f b 3 ms Fast BPAP decay time constant
τ s b 25 ms Slow BPAP decay time constant

Metaplasticity

To ensure the stabilization of synaptic weights after several laps around the track, we use metaplasticity to limit NMDAR conductance ( g N ) after repeated high-frequency postsynaptic stimulation. Metaplasticity follows a voltage-dependent kinetic model of NMDAR insertion and removal from the synapse as prescribed by the equation below:

d g N d t = a [ k + ( g t - g N ) - k - ( V - V r e s t ) n g N ]

a is a scaling factor used to control the rate of change in NMDAR conductance. k + is the insertion rate of unused NMDA receptors into the synapse, which we set at 8 × 10 - 5 . k - ( V - V r e s t ) n is the removal rate of NMDA receptors from the synapse: we use k - = 8 × 10 - 7 , n = 2, and V r e s t as the cell resting potential. Like our voltage-dependent H-function, V in the NMDAR conductance equation represents the postsynaptic voltage (as opposed to the membrane voltage). g t is the maximum value for NMDAR conductance, which we set at - 1 × 10 - 3 . Note that all NMDAR conductance values are negative. We depict equilibrium NMDAR conductances as a function of voltage in [link] below.

Voltage-Dependence of Metaplasticity. Plot of equilibrium conductance values at fixed voltages. Depolarized voltages result in lower conductance values.

Questions & Answers

A golfer on a fairway is 70 m away from the green, which sits below the level of the fairway by 20 m. If the golfer hits the ball at an angle of 40° with an initial speed of 20 m/s, how close to the green does she come?
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A mouse of mass 200 g falls 100 m down a vertical mine shaft and lands at the bottom with a speed of 8.0 m/s. During its fall, how much work is done on the mouse by air resistance
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Can you compute that for me. Ty
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what is inorganic
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Chemistry is a branch of science that deals with the study of matter,it composition,it structure and the changes it undergoes
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A ball is thrown straight up.it passes a 2.0m high window 7.50 m off the ground on it path up and takes 1.30 s to go past the window.what was the ball initial velocity
Krampah Reply
2. A sled plus passenger with total mass 50 kg is pulled 20 m across the snow (0.20) at constant velocity by a force directed 25° above the horizontal. Calculate (a) the work of the applied force, (b) the work of friction, and (c) the total work.
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you have been hired as an espert witness in a court case involving an automobile accident. the accident involved car A of mass 1500kg which crashed into stationary car B of mass 1100kg. the driver of car A applied his brakes 15 m before he skidded and crashed into car B. after the collision, car A s
Samuel Reply
can someone explain to me, an ignorant high school student, why the trend of the graph doesn't follow the fact that the higher frequency a sound wave is, the more power it is, hence, making me think the phons output would follow this general trend?
Joseph Reply
Nevermind i just realied that the graph is the phons output for a person with normal hearing and not just the phons output of the sound waves power, I should read the entire thing next time
Joseph
Follow up question, does anyone know where I can find a graph that accuretly depicts the actual relative "power" output of sound over its frequency instead of just humans hearing
Joseph
"Generation of electrical energy from sound energy | IEEE Conference Publication | IEEE Xplore" ***ieeexplore.ieee.org/document/7150687?reload=true
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progressive wave
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A string is 3.00 m long with a mass of 5.00 g. The string is held taut with a tension of 500.00 N applied to the string. A pulse is sent down the string. How long does it take the pulse to travel the 3.00 m of the string?
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Source:  OpenStax, The art of the pfug. OpenStax CNX. Jun 05, 2013 Download for free at http://cnx.org/content/col10523/1.34
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