AlphaSynapse vs Exp2Syn

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rllin

AlphaSynapse vs Exp2Syn

Post by rllin »

These two should be interchangeable code wise right? Besides AlphaSynapse having only one tau and not taking NetCon's weight for equation use, they should be the same right? They can both be connected to sources with NetCons?
ted
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Re: AlphaSynapse vs Exp2Syn

Post by ted »

ExpSyn and Exp2Syn are driven by events. AlphaSynapse is not--it produces a single conductance transient at a time specified by its onset parameter.
rllin

Re: AlphaSynapse vs Exp2Syn

Post by rllin »

Ah, thank you. I just reread and found that they are both also alpha functions so that's good too.
rllin

Re: AlphaSynapse vs Exp2Syn

Post by rllin »

G = weight * factor * (exp(-t/tau2) - exp(-t/tau1))
This is the equation given for Exp2Syn.
If tau2 is close to tau1 this has the property that the maximum value is weight and occurs at t = tau1
When tau1 is close to tau2, shouldn't G approach 0? Am I missing something here? Thanks!
ted
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Re: AlphaSynapse vs Exp2Syn

Post by ted »

factor
rllin

Re: AlphaSynapse vs Exp2Syn

Post by rllin »

Your (exp(-t/tau2) - exp(-t/tau1)) term would still be 0, no?
ted
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Re: AlphaSynapse vs Exp2Syn

Post by ted »

Read the source code and discover that the condition
tau1 = tau2
is trapped by a conditional statement that forces a nonzero difference between them. This happens before the value of factor is calculated.
rllin

Re: AlphaSynapse vs Exp2Syn

Post by rllin »

Ah, thanks!
rllin

Re: AlphaSynapse vs Exp2Syn

Post by rllin »

Also, AlphaSynapse has
the property that the maximum value is gmax and occurs at
t = delay + tau.
What is this delay? Thanks!
ted
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Re: AlphaSynapse vs Exp2Syn

Post by ted »

A typographical error. The revised documentation will read
the maximum value is gmax and occurs at
t = onset + tau.
rllin

Re: AlphaSynapse vs Exp2Syn

Post by rllin »

Ah, thank you. And just as a note to people that might have the same question, this arrives simply by finding the peak through setting the time derivative to zero.
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