6 May
2020
6 May
'20
11:19 a.m.
Dear all,
I hope you are in staying safe.
I'm working on a balanced network consisting of "iaf_cond_exp" neurone
model.
I want to have the control over these parameters at the same time:
- increasing the synaptic decay time.
- reducing the synaptic weight.
The goal is to make the area under the synaptic current, constant. So that we know that
the only parameter that is affecting on the network, is synaptic delay.
I wonder if you know of any furmula in mathematics or any algorithm, that can help me,
making this process automatic. And keeping the area under the curve, a constant value.
Best wishes,
Nosratullah
6 May
6 May
10:24 p.m.
Dear Nosratullah,
sorry, can you perhaps rephrase your question? It is unclear what you
mean by "make the area under the synaptic current constant".
In networks with conductance based synapses, there is no such thing as
*the* synaptic current. For conductance based synapses, the current
I_ij(t)=g_ij(t)*(V_i(t)-E_j) at synapse j->i is determined by the
membrane potential V_i(t) of the target cell i, which, in turn, is
affected by the synaptic currents at all synapses of this neuron (for
point neurons). As the membrane potential V_i(t) is strongly fluctuating
in balanced networks, the synaptic-current responses I_ij(t) triggered
by input spikes from neuron j are different (in shape) for each incoming
spike, even if the weight and time constant of the conductance kernel
are fixed.
You can of course easily preserve the area
A = \int dt g_ij(t) = w_ij * tau
under the exponential conductance kernel
g_ij(t)=w_ij * exp(-t/tau) * H(t)
(with H(t)=Heaviside function) by compensating a change in its amplitude
w_ij ("weight") by the time constant tau = A/w_ij. But this won't make
I_ij(t) constant.
Best,
Tom
On 06.05.20 11:19, Nosratullah M wrote:
Dear all,
I hope you are in staying safe.
I'm working on a balanced network consisting of "iaf_cond_exp" neurone
model.
I want to have the control over these parameters at the same time:
- increasing the synaptic decay time.
- reducing the synaptic weight.
The goal is to make the area under the synaptic current, constant. So
that we know that the only parameter that is affecting on the network,
is synaptic delay.
I wonder if you know of any furmula in mathematics or any algorithm,
that can help me, making this process automatic. And keeping the area
under the curve, a constant value.
Best wishes,
Nosratullah
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--
---
Dr. Tom Tetzlaff
Institute of Neuroscience and Medicine (INM-6)
Computational and Systems Neuroscience &
Institute for Advanced Simulation (IAS-6)
Theoretical Neuroscience
Jülich Research Centre and JARA
Jülich, Germany
phone: +49-2461-61-85166 (office)
http://www.fz-juelich.de/SharedDocs/Personen/INM/INM-6/EN/Tetzlaff_Tom.html
------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------
Forschungszentrum Juelich GmbH
52425 Juelich
Sitz der Gesellschaft: Juelich
Eingetragen im Handelsregister des Amtsgerichts Dueren Nr. HR B 3498
Vorsitzender des Aufsichtsrats: MinDir Volker Rieke
Geschaeftsfuehrung: Prof. Dr.-Ing. Wolfgang Marquardt (Vorsitzender),
Karsten Beneke (stellv. Vorsitzender), Prof. Dr.-Ing. Harald Bolt
------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------
7 May
7 May
8:40 p.m.
Dear Tom,
Thanks for the time you spent answering my question and Sorry for not including enough
details for the question.
I added a figure to describe the question. I’m using ‘oaf_cond_exp’ neuron model in a
balanced network. I want to change the synaptic decay time while the area under the
conductance curve remain a constant value as it has shown in the figure. Mentioning the
synaptic conductance as synaptic current was definitely a mistake.
Regards,
Nosratullah Mohammadi
On 07 May 2020 AD, at 00:54, Tom Tetzlaff
<t.tetzlaff(a)fz-juelich.de> wrote:
Dear Nosratullah,
sorry, can you perhaps rephrase your question? It is unclear what you
mean by "make the area under the synaptic current constant".
In networks with conductance based synapses, there is no such thing as
*the* synaptic current. For conductance based synapses, the current
I_ij(t)=g_ij(t)*(V_i(t)-E_j) at synapse j->i is determined by the
membrane potential V_i(t) of the target cell i, which, in turn, is
affected by the synaptic currents at all synapses of this neuron (for
point neurons). As the membrane potential V_i(t) is strongly fluctuating
in balanced networks, the synaptic-current responses I_ij(t) triggered
by input spikes from neuron j are different (in shape) for each incoming
spike, even if the weight and time constant of the conductance kernel
are fixed.
You can of course easily preserve the area
A = \int dt g_ij(t) = w_ij * tau
under the exponential conductance kernel
g_ij(t)=w_ij * exp(-t/tau) * H(t)
(with H(t)=Heaviside function) by compensating a change in its amplitude
w_ij ("weight") by the time constant tau = A/w_ij. But this won't make
I_ij(t) constant.
Best,
Tom
On 06.05.20 11:19, Nosratullah M wrote:
Dear all,
I hope you are in staying safe.
I'm working on a balanced network consisting of "iaf_cond_exp" neurone
model.
I want to have the control over these parameters at the same time:
- increasing the synaptic decay time.
- reducing the synaptic weight.
The goal is to make the area under the synaptic current, constant. So
that we know that the only parameter that is affecting on the network,
is synaptic delay.
I wonder if you know of any furmula in mathematics or any algorithm,
that can help me, making this process automatic. And keeping the area
under the curve, a constant value.
Best wishes,
Nosratullah
_______________________________________________
NEST Users mailing list -- users(a)nest-simulator.org
To unsubscribe send an email to users-leave(a)nest-simulator.org
--
---
Dr. Tom Tetzlaff
Institute of Neuroscience and Medicine (INM-6)
Computational and Systems Neuroscience &
Institute for Advanced Simulation (IAS-6)
Theoretical Neuroscience
Jülich Research Centre and JARA
Jülich, Germany
phone: +49-2461-61-85166 (office)
http://www.fz-juelich.de/SharedDocs/Personen/INM/INM-6/EN/Tetzlaff_Tom.html
------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------
Forschungszentrum Juelich GmbH
52425 Juelich
Sitz der Gesellschaft: Juelich
Eingetragen im Handelsregister des Amtsgerichts Dueren Nr. HR B 3498
Vorsitzender des Aufsichtsrats: MinDir Volker Rieke
Geschaeftsfuehrung: Prof. Dr.-Ing. Wolfgang Marquardt (Vorsitzender),
Karsten Beneke (stellv. Vorsitzender), Prof. Dr.-Ing. Harald Bolt
------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------
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8 May
8 May
9:59 a.m.
Dear Nosratullah,
thanks for the clarification. As explained in my last email, preserving
the area under the exponential conductance kernel (i.e. the one used in
iaf_cond_exp) while changing the time constant is straight forward.
Scaling the weight w by the inverse of the synaptic time constant tau
will do the job. With
w=A/tau
the integral of w*exp(-t/tau)*H(t) is constant and equal to A.
Best,
Tom
On 07.05.20 20:40, nosratullah mohammadi wrote:
Dear Tom,
Thanks for the time you spent answering my question and Sorry for not
including enough details for the question.
I added a figure to describe the question. I’m using ‘oaf_cond_exp’
neuron model in a balanced network. I want to change the synaptic decay
time while the area under the conductance curve remain a constant value
as it has shown in the figure. Mentioning the synaptic conductance as
synaptic current was definitely a mistake.
Regards,
Nosratullah Mohammadi
--
---
Dr. Tom Tetzlaff
Institute of Neuroscience and Medicine (INM-6)
Computational and Systems Neuroscience &
Institute for Advanced Simulation (IAS-6)
Theoretical Neuroscience
Jülich Research Centre and JARA
Jülich, Germany
phone: +49-2461-61-85166 (office)
http://www.fz-juelich.de/SharedDocs/Personen/INM/INM-6/EN/Tetzlaff_Tom.html
On 07 May 2020 AD, at 00:54, Tom Tetzlaff
<t.tetzlaff(a)fz-juelich.de
<mailto:t.tetzlaff@fz-juelich.de>> wrote:
Dear Nosratullah,
sorry, can you perhaps rephrase your question? It is unclear what you
mean by "make the area under the synaptic current constant".
In networks with conductance based synapses, there is no such thing as
*the* synaptic current. For conductance based synapses, the current
I_ij(t)=g_ij(t)*(V_i(t)-E_j) at synapse j->i is determined by the
membrane potential V_i(t) of the target cell i, which, in turn, is
affected by the synaptic currents at all synapses of this neuron (for
point neurons). As the membrane potential V_i(t) is strongly fluctuating
in balanced networks, the synaptic-current responses I_ij(t) triggered
by input spikes from neuron j are different (in shape) for each incoming
spike, even if the weight and time constant of the conductance kernel
are fixed.
You can of course easily preserve the area
A = \int dt g_ij(t) = w_ij * tau
under the exponential conductance kernel
g_ij(t)=w_ij * exp(-t/tau) * H(t)
(with H(t)=Heaviside function) by compensating a change in its amplitude
w_ij ("weight") by the time constant tau = A/w_ij. But this won't make
I_ij(t) constant.
Best,
Tom
On 06.05.20 11:19, Nosratullah M wrote:
Dear all,
I hope you are in staying safe.
I'm working on a balanced network consisting of "iaf_cond_exp" neurone
model.
I want to have the control over these parameters at the same time:
- increasing the synaptic decay time.
- reducing the synaptic weight.
The goal is to make the area under the synaptic current, constant. So
that we know that the only parameter that is affecting on the network,
is synaptic delay.
I wonder if you know of any furmula in mathematics or any algorithm,
that can help me, making this process automatic. And keeping the area
under the curve, a constant value.
Best wishes,
Nosratullah
_______________________________________________
NEST Users mailing list -- users(a)nest-simulator.org
<mailto:users@nest-simulator.org>
To unsubscribe send an email to users-leave(a)nest-simulator.org
<mailto:users-leave@nest-simulator.org>
--
---
Dr. Tom Tetzlaff
Institute of Neuroscience and Medicine (INM-6)
Computational and Systems Neuroscience &
Institute for Advanced Simulation (IAS-6)
Theoretical Neuroscience
Jülich Research Centre and JARA
Jülich, Germany
phone: +49-2461-61-85166 (office)
http://www.fz-juelich.de/SharedDocs/Personen/INM/INM-6/EN/Tetzlaff_Tom.html
------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------
Forschungszentrum Juelich GmbH
52425 Juelich
Sitz der Gesellschaft: Juelich
Eingetragen im Handelsregister des Amtsgerichts Dueren Nr. HR B 3498
Vorsitzender des Aufsichtsrats: MinDir Volker Rieke
Geschaeftsfuehrung: Prof. Dr.-Ing. Wolfgang Marquardt (Vorsitzender),
Karsten Beneke (stellv. Vorsitzender), Prof. Dr.-Ing. Harald Bolt
------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------
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1691
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3 comments
3 participants
participants (3)
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Nosratullah M -
nosratullah mohammadi -
Tom Tetzlaff