Computing LFP with use_fast_imem and extra_scatter_gather
Posted: Wed Dec 04, 2019 2:51 pm
I have successfully implemented computation of the LFP in a previous network model using cvode.use_fast_imem and cvode.extra_scatter_gather (see viewtopic.php?f=8&t=3656&p=15713&hilit= ... m+1#p15713)
I am trying to use this same approach in a new network model, but I am having some trouble. I am trying to record the LFP contribution from a subset of neurons in a network of 800 total neurons. The problem is that the LFP registers action potentials, but not post-synaptic potentials. For instance, I ran a simulation in which I recorded both the intracellular voltage and the LFP from one single neuron in the network. (I recorded the LFP from a single neuron by defining a subset of sections belonging to just that neuron, then passing that subset of sections to a callback using extra_scatter_gather.) The intracellular voltage shows EPSP’s:
But the LFP is a perfect flatline (and yes, I checked to make sure there are not small fluctuations when you zoom in):
But if I increase the strength of excitatory synapses onto this cell, then spikes are elicited:
And this does show up in the LFP:
I am at a loss to explain why AP’s register in the LFP, but PSP’s do not. I made a toy simulation with just one neuron, but unfortunately I was unable to replicate the problem (i.e., PSP's did show up in the LFP in the toy simulation).
Any ideas what the problem might be, or how I might troubleshoot this?
I am trying to use this same approach in a new network model, but I am having some trouble. I am trying to record the LFP contribution from a subset of neurons in a network of 800 total neurons. The problem is that the LFP registers action potentials, but not post-synaptic potentials. For instance, I ran a simulation in which I recorded both the intracellular voltage and the LFP from one single neuron in the network. (I recorded the LFP from a single neuron by defining a subset of sections belonging to just that neuron, then passing that subset of sections to a callback using extra_scatter_gather.) The intracellular voltage shows EPSP’s:
But the LFP is a perfect flatline (and yes, I checked to make sure there are not small fluctuations when you zoom in):
But if I increase the strength of excitatory synapses onto this cell, then spikes are elicited:
And this does show up in the LFP:
I am at a loss to explain why AP’s register in the LFP, but PSP’s do not. I made a toy simulation with just one neuron, but unfortunately I was unable to replicate the problem (i.e., PSP's did show up in the LFP in the toy simulation).
Any ideas what the problem might be, or how I might troubleshoot this?