Re: [Genesis-sim-users] V-clamp on dendrites?

[Kai Du <kai...@gm...>]

Hi Dieter Jarger,

Thank you for your suggestions. It works!
I have to use a very small "gain" to avoid clamp to be crushed:
========================================================
 setfield ^ gain 1e-9 tau_i 1e-7 tau_d 1.0e-8 saturation 1e-8
========================================================

These are the parameters used in my current clamp model and works well for
my detailed model ( compartment length is ~ 5um ).

2015-03-03 14:31 GMT-08:00 Jaeger, Dieter <dj...@em...>:

>  Hello –
>
>
>
> how small are you dendritic compartments?  Any one compartment in the
> dendrite that is abnormally small can cause such problems.  We use the
> attached for a voltage clamp that worsk well in the soma of simulated
> neurons (we haven’t clamped dendrites, but it **SHOULD** be similar).
> You may have to decrease the gain if you are in high-input resistance
> area.  Your taus and gain are too aggressive.  This wouldn’t work in a real
> preparation, either!
>
>
>
> -Dieter
>
>
>
>
>
>
>
> *From:* Kai Du [mailto:kai...@gm...]
> *Sent:* Monday, March 02, 2015 12:50 PM
> *To:* gen...@li...
> *Subject:* [Genesis-sim-users] V-clamp on dendrites?
>
>
>
> Hi All Genesis Users,
>
>
>
> Do you ever have any experience in applying V-clamp on dendrites?
>
>
>
> I just tried to apply the V-clamp to dendrites and I found it had to use a
> time step of 1e-20 second!!! or  simulations were simply crushed!
>
>
>
> Do you how can we change the parameters in the  "V-clamp" settings so we
> can use a bigger time-step to clamp dendrites.
>
>
>
> This is what I use now:
>
> ===================================================
>
> create RC /clamp/lowpass
>
>   setfield ^ R 1 C 1e-5
>
>
>
>  create diffamp /clamp/vClamp
>
>    setfield ^ saturation 999.0 gain 1
>
>
>
>   create PID /clamp/PID     // Values taken from squid example
>
>  setfield ^ gain 1e-5 tau_i 1e-5 tau_d 1e-7 saturation 999.0
>
> ============================================================
>
>
>
>
>
> btw, I also tried V-clamp on passive dendrites, it also need a very
> "small" time-step, say, 1e-14 second. By contrast, the V-clamp works well
> to the soma -- a time step of 7e-6 second was needed.
>
>
>
> --
>
> Best Regards,
>
> Kai Du,
> PhD student
> Department of Neuroscience
> Karolinska Institutet
> Retzius väg 8
> S-17177 Stockholm, Sweden
>



-- 
Best Regards,

Kai Du,
PhD student
Department of Neuroscience
Karolinska Institutet
Retzius väg 8
S-17177 Stockholm, Sweden