// This hoc file reproduces simulations of a place cell on a linear track formed from 32 excitatory theta cell inputs
// (Fig. 9B of Welday et al.)
//
// Theta cell spike trains (shown in the Fig. 9B rasters) are read into NEURON from disk by the accompanying hoc file:
// read_thetaspikes_Fig9B.hoc.
//
//To save the postsynaptic neuron's (place cell's) spike times, type:
//
// >>load_file("savespikes.hoc")
//
//at the interpreter prompt after the simulation has finished running. Spikes will be saved in a file called 'SPIKOUT.dat'.
//
//To save the postsynaptic neuron's (place cell's) membrane voltage trace, type:
//
// >>load_file("savevm.hoc")
//
//at the interpreter prompt after the simulation has finished running. Spikes will be saved in a file called 'VmOUT.dat'.
load_file("nrngui.hoc")
// -----------------------------------------------------------------
// read theta cell spike trains from disk files into NEURON vectors
// -----------------------------------------------------------------
load_file("placetrack_vecstims_Fig9B.ses") //create vecstim objects for delivering theta spike trains to the model neuron
numinputs = 32 //number of inhibitory theta inputs to the model neuron
objref evec[numinputs] //array of event vectors (VecStim.mod) for reading theta spike trains
objref spikefile //file object through which to read in theta cell spike times from disk
objref pplist //list of point processes containing theta spike trains
objref vmvec
objref vmfile
spikefile = new File()
pplist = new List()
vmfile = new File()
load_file("read_thetaspikes_Fig9B.hoc") //read in theta cell spike timestamps from files
simlength=1000*200/25
// --------------------------------------------------------------
// build a single-compartment postsynaptic cell
// --------------------------------------------------------------
ra = 150 // axial resistance through cytoplasm (ohms)
global_ra = ra
rm = 15000 // passive membrane resistance (ohms)
c_m = 1 // membrane capacitance (microFarads per centimeter squared, uF/cm^2)
create soma //single somatic compartment
access soma
PI=3.14159
{L=10/PI diam=10}
nseg=1
Ra = ra
cm = c_m
vmvec = new Vector()
vmvec.record(&v(.5))
//Insert voltage-activated persistent sodium current (Nap.mod)
insert nap
gbar_nap=.00005 //Nap conductance
sh_nap=-10 //Nap voltage activation threshold shift parameter (mV)
//Insert Hodkin-Huxley kinetics (hh.mod, standard NEURON mechanism)
insert hh
gkbar_hh=.005 //delayed rectifier K+ conductance
gnabar_hh=.05 //voltage-gated Na+ conductance
el_hh=-65 //leak reversal potential
gl_hh=1/rm //leak conductance
// --------------------------------------------------------------
// connect theta spike train inputs to the model neuron
// --------------------------------------------------------------
objref nclist //list of netcon objects for synaptic connections
nclist = new List()
load_file("placetrack_GABAinputs_Fig9B.ses") //synaptic currents
// Uncomment the following two lines to run the simulation with excitatory theta cell inputs (uncomment for inhibitory inputs):
synw=.0000017 //set conductance of AMPA synapses
gbar_nap=0 //uncomment to shut off Nap conductance
// Uncomment the following three lines to run the simulation with inhibitory theta cell inputs (comment for excitatory inputs):
//Erev_AMPA_S=-80 //set reversal potential to -80 mV to convert the AMPA synapse to GABA
//Beta_AMPA_S=.12 //slow down the decay time a little bit for GABA currents
//synw=.001 //set conductance of GABA synapses
// Uncomment the following two lines to disable active currents and run the simulation without spikes (comment to run with spikes):
//gkbar_hh=0 //delayed rectifier K+ conductance
//gnabar_hh=0 //voltage-gated Na+ conductance
for i=0,numinputs-1 {
nclist.append(new NetCon(pplist.o(i), AMPA_S[i], -20, 1, synw)) //make the input connections
}
tstop=simlength
// ------------------------------------------------------------------------
// store model neuron's spike times in a vector to be saved later if needed
// ------------------------------------------------------------------------
objref spiketimes //vector in which to store timestamps of spikes generated by the model neuron
objref spikenc //netcon object through which spikes are passed into the 'spiketimes' vector
objref null //null object
spiketimes = new Vector()
spikenc = new NetCon(&v(0.5), null)
spikenc.threshold = -25 // store a spike timestamp if the postsynaptic membrane voltage exceeds -25 mV
spikenc.record(spiketimes) // record the spike times to the 'spiketimes' vector
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