Suggestion for dynamic synaptic inputs

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Suggestion for dynamic synaptic inputs

Postby ylzang » Tue Aug 15, 2017 11:07 pm

I have built a cell model and now I want to do the in vivo simulations. When the animal is at resting condition, there are only spontaneous/background synaptic inputs. To make it simple, I assume there are 1000 synaptic contacts uniformly formed on the dendrite from another type of cells. At resting condition, then 1000 synapses will randomly activate at a very low rate. I can simulate resting condition by setting the activation time of each synapse uniformly distributed between 0 and 1000/Firing_rate_resting. Then I am confused how to do the following simulation. once the animal receives stimulus or have some movement, the activation frequency of the synapses will increase significantly in a dynamic way to code the sensory input or the movement. How should I implement this kind of synaptic inputs together with the resting state? Thanks.
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Re: Suggestion for dynamic synaptic inputs

Postby ted » Fri Aug 18, 2017 3:54 pm

What do you need help with--attaching a bunch of synapses to a model cell, or making the presynaptic firing rates change in a way that represents the effect of a stimulus?
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Re: Suggestion for dynamic synaptic inputs

Postby ylzang » Sun Aug 20, 2017 9:05 pm

ted wrote:What do you need help with--attaching a bunch of synapses to a model cell, or making the presynaptic firing rates change in a way that represents the effect of a stimulus?

Thanks Ted. The second one would be the question.
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Re: Suggestion for dynamic synaptic inputs

Postby ted » Sun Aug 20, 2017 11:10 pm

To go any further, you will have to provide a mathematical description of the effect of a stimulus on presynaptic firing rate. It would be best if your description is based on experimental evidence.
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Re: Suggestion for dynamic synaptic inputs

Postby ylzang » Mon Aug 21, 2017 9:44 pm

ted wrote:To go any further, you will have to provide a mathematical description of the effect of a stimulus on presynaptic firing rate. It would be best if your description is based on experimental evidence.

Yes, I am trying to simulate the cell spiking in vivo. It includes two stages, the resting state and the state after receiving stimulus (or locomotion).
At resting state, the cell receives spontaneous excitatory synaptic inputs (just ignore the inhibitory synaptic input to make it simple). These spontaneous synaptic inputs should be poisson process with low average firing rate.
Once I exert some sensory stimulus (or the animal has some locomotion), the cell's presynaptic input firing rate will temporarily increase significantly and linearly code the motion or the stimulus (I just make it simple here). I will send the image to your email. Sorry I don't know how to upload an image here. I guess for this case, I may have to record the presynaptic spike timing and then read it into NEURON?
Or for a first try, once the cell receives stimulus, the presynaptic input firing rate (signal) is like a sinusoidal wave FR = sin((t-stimulus_onset)/10), when t<stimulus_onset or t>stimulus_onset+10*pi. The background presynaptic firing rate is 0.2 Hz (noise).
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Re: Suggestion for dynamic synaptic inputs

Postby ted » Mon Aug 21, 2017 11:13 pm

once the cell receives stimulus, the presynaptic input firing rate (signal) is like a sinusoidal wave FR = sin((t-stimulus_onset)/10), when t<stimulus_onset or t>stimulus_onset+10*pi.
sin((t-stimulus_onset)/10) is negative half of the time. Would you like to revise the expression for firing rate?
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Re: Suggestion for dynamic synaptic inputs

Postby ylzang » Tue Aug 22, 2017 8:41 am

ted wrote:
once the cell receives stimulus, the presynaptic input firing rate (signal) is like a sinusoidal wave FR = sin((t-stimulus_onset)/10), when t<stimulus_onset or t>stimulus_onset+10*pi.
sin((t-stimulus_onset)/10) is negative half of the time. Would you like to revise the expression for firing rate?

Yes, can we set it to be zero when FR<0 (this is more close to reality)? or just make FR = abs(sin((t-stimulus_onset)/10))?
Now I just want to explore how I can realise a presynaptic input as what I have described. I think I can modify it more reasonable later. Thanks again.
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