Impedance spectrum in cortical tissue: implications for LFP signal propagation (Miceli et al. 2017)

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Accession:224923
" ... Here, we performed a detailed investigation of the frequency dependence of the conductivity within cortical tissue at microscopic distances using small current amplitudes within the typical (neuro)physiological micrometer and sub-nanoampere range. We investigated the propagation of LFPs, induced by extracellular electrical current injections via patch-pipettes, in acute rat brain slice preparations containing the somatosensory cortex in vitro using multielectrode arrays. Based on our data, we determined the cortical tissue conductivity over a 100-fold increase in signal frequency (5-500 Hz). Our results imply at most very weak frequency-dependent effects within the frequency range of physiological LFPs. Using biophysical modeling, we estimated the impact of different putative impedance spectra. Our results indicate that frequency dependencies of the order measured here and in most other studies have negligible impact on the typical analysis and modeling of LFP signals from extracellular brain recordings."
Reference:
1 . Miceli S, Ness TV, Einevoll GT, Schubert D (2017) Impedance Spectrum in Cortical Tissue: Implications for Propagation of LFP Signals on the Microscopic Level Eneuro 4:1-15
Model Information (Click on a link to find other models with that property)
Model Type: Extracellular; Neuron or other electrically excitable cell;
Brain Region(s)/Organism:
Cell Type(s): Neocortex L5/6 pyramidal GLU cell;
Channel(s): I Na,p; I Na,t; I L high threshold; I A; I h; I K,Ca; I Calcium; I A, slow;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: Python; NEURON;
Model Concept(s): Extracellular Fields; Methods; Simplified Models; Detailed Neuronal Models;
Implementer(s):
Search NeuronDB for information about:  Neocortex L5/6 pyramidal GLU cell; I Na,p; I Na,t; I L high threshold; I A; I h; I K,Ca; I Calcium; I A, slow;
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tissue_impedance_impact
hay
sim_results
ampa.mod
Ca_HVA.mod *
Ca_LVAst.mod *
CaDynamics_E2.mod *
epsp.mod *
glutamate.mod
Ih.mod *
Im.mod *
K_Pst.mod *
K_Tst.mod *
Nap_Et2.mod
NaTa_t.mod *
NaTs2_t.mod
siniclamp.mod
SK_E2.mod *
SKv3_1.mod *
stim.mod
cell1.hoc
cell1.rot
custom_codes.hoc
hay_active_declarations.py
                            
COMMENT
Since this is an electrode current, positive values of i depolarize the cell
and in the presence of the extracellular mechanism there will be a change
in vext since i is not a transmembrane current but a current injected
directly to the inside of the cell.
ENDCOMMENT

NEURON {
        POINT_PROCESS SinIClamp
        RANGE del, dur, pkamp, freq, phase, bias
        ELECTRODE_CURRENT i
}

UNITS {
        (nA) = (nanoamp)
             }

PARAMETER {
        del=5   (ms)
        dur=200   (ms)
        pkamp=1 (nA)
        freq=1  (Hz)
        phase=0
        bias=0  (nA)
        PI=3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342117067982148086513282
}

ASSIGNED {
        i (nA)
}

BREAKPOINT {
       at_time(del)
       at_time(del + dur)

       if (t < del) {
      i=0   
   }else{ 
            if (t < del+dur) {
           i = -pkamp*sin(2*PI*freq*(t-del)*(0.001)+phase)-bias
      }else{ 
           i = 0
}}}

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