This is the model for the paper: Jercog PE, Svirskis G, Kotak VC, Sanes DH, Rinzel J (2010) Asymmetric excitatory synaptic dynamics underlie interaural time difference processing in the auditory system. PLoS Biol 8:e1000406 The model code was contributed by Pablo Jercog. Two Models for synaptic inputs statistics for the MSO neuron. These two models generate the conductance, membrane potential and low threshold potassium current time courses for bilateral inputs at different ITDs. These codes also produce ITD-tuning curves for the cell model given these synaptic input models. This Medial Superior Olivary (MSO) neuron model generates responses to two synaptic input trains that mimic interaural time delay (ITD) inputs from the two ears for pure tone stimuli. An MSO neuron generates spikes if the 'bilateral' inputs are nearly coincident in time, performing a crucial neuronal computation in the mammalian brainstem for sound localization. The model is a point neuron model with ionic currents from Rothman & Mannis (2003) and with an update of the low threshold potassium current (IKLT) measured in-vitro by Mathews & Jercog et al (2010). This model in conjunction with the synaptic input models presented here has been used to gain insight into mechanisms that account for experimentally observed asymmetries in ITD tuning (Brand et al, 2002). Asymmetry and displacement of the ITD response function is achieved in the model by the interplay between asymmetry of the excitatory inputs arriving from the two sides and the precise voltage dependent activation of IKLT. In Jercog et al (2010) we propose two different mathematical ways, physiologically plausible scenarios, of generating the asymmetry in the bilateral synaptic input events. Here, we present two models for simulating the stochastic synaptic input trains. Model 1: The "Gaussian-jittered poisson-modulated synaptic inputs model" is a simple model that we used in figure 3 (Jercog et al 2010) for presynaptic event times. It involves a partially rectified-sinusoidal time-modulated poisson function with additional gaussian jitter to further randomize each individual event time on a given cycle. This model best resembles our recorded data (in vitro, bilaterally stimulated MSO neuron) in terms of variability in composite EPSP amplitude, half-width and rising slope. A potential source of gaussian statistical distribution that we include in the time of presynaptic events is attributed to a possible distribution of delays of pre-synaptic pathways' propagation-time (say, gaussian distribution of axonal lengths) and location of pre-synaptic terminals over the MSO dendrites (also gaussian as the simplest biological plausible distribution). Model 2: The "Carney-like" synaptic input model generates presynaptic input event times using Carney's 1993 auditory nerve model, modifying the parameter values in order to obtain summated EPSPs with a rising slope in the range of values as observed in our experiments (figure 2 in Jercog et al 2010). This model was used as a proof of principles to generate figures 4 and 5 (Jercog et al 2010) based on a model, well know in the auditory community. See also: Carney 1993, Brughera et al 1996, Rothman et al 1993, first proposed by Johnson et al 1986. How to run the models: # gcc [code-name.c] -lm -O3 -o [executable-name] # ./[executable-name] #################################################################### Outputs from these codes: (Plotting the outputs in gnuplot or matlab it's easy) "Model1_STA_epsg_epsp_iklt.dat" different averaged values triggered by the spike detection first column = ITD second column = time before the spike's peak (ms) third column = spike triggered voltage average forth column = spike triggered voltage lowest-range trace fifth column = spike triggered voltage highest-range trace sixth column = non-spike triggered voltage average seventh column = non-spike triggered voltage lowest-range trace eighth column = non-spike triggered voltage highest-range trace ninth column = non-spike triggered voltage std.dev. tenth column = spike triggered low-treshold potassium current (IKLT) average eleventh column = spike triggered low-treshold potassium conductance (gKLT) average twelfth column = non-spike triggered low-treshold potassium conductance (gKLT) average thirteenth column = non-spike triggered ipsilateral excitatory conductance average fourteenth column = non-spike triggered contralateral excitatory conductance average fifteenth column = spike triggered ipsilateral excitatory conductance average sixteenth column = spike triggered contralateral excitatory conductance average "Model1_train_EPSGs-EPSPs.dat" is the train of EPSPs and EPSGs for ITD = 0msec. first column=time second column=voltage time course third column = sinusoidal time modulation of the synaptic poisson rate forth column = total synaptic input fifth column = ipsilateral excitatory synaptic input sixth column = contralateral excitatory synaptic input "Model1_ITD-curve.dat" ITD response function first column = ITD second column = spike count/(total number of sinusoidal cycles that modulate the poisson rate) #################################################################### "Model2_syn-events-ipsi.dat", "Model2_syn-events-contra.dat" are the output files that contain: first column=current time of the simulation; second column= index of the synaptic input that is activated third column= the exact time where the i-th event is located forth column= value of the poisson event rate function at the time of the decision of creating a synaptic event. (ipsi and contra correspond to each bilateral input.) "Model2_train_EPSGs-EPSPs.dat" is the train of EPSPs and EPSGs for ITD = 0msec. first column=time second column=voltage time course third column = sinusoidal time modulation of the synaptic poisson rate forth column = total synaptic input fifth column = ipsilateral excitatory synaptic input sixth column = contralateral excitatory synaptic input "Model2_ITD-curve.dat" ITD response function first column = ITD second column = spike count/(total number of sinusoidal cycles that modulate the poisson rate ) "Model2_STA_epsg_epsp_iklt.dat" different averaged values triggered by the spike detection first column = time previous to the spike's peak second column=spike triggered voltage average previous to the spike's peak third column = spike triggered ipsilateral EPSG average previous to the spike's peak forth column = spike triggered contralateral EPSG average previous to the spike's peak fifth column = spike triggered contralateral IPSG average previous to the spike's peak