This is the README for the model associated with the paper: Zhou Y, Colburn HS (2010) A modeling study of the effects of membrane afterhyperpolarization on spike interval statistics and on ILD encoding in the lateral superior olive. J Neurophysiol 103:2355-71 This model was contributed by Yi Zhou.

A: Introduction

This simulation study investigated how membrane afterhyperpolarization (AHP) influences spiking activity of neurons in the Lateral Superior Olive (LSO). The model incorporates a general integrate-and-fire spiking mechanism with a first-order adaptation channel. Simulations focus on differentiating the effects of GAHP, tau_AHP, and input strength on (1) spike interval statistics, such as negative serial correlation and chopper onset, and (2) neural sensitivity to interaural level difference (ILD) of LSO neurons. The model simulated electrophysiological data collected in cat LSO (Tsuchitani and Johnson, 1985). The complete set of simulation results were reported in Zhou and Colburn (2010).

B: Download

This model was written in the NEURON simulation environment. After installing NEURON, download and unzip the model package to a local directory (e.g., C:/Neuron/LSO). Use nrnivmodl to compile mod files, and then execute the main NEURON programs (LSO_current_input.hoc or LSO_synaptic_input.hoc). The LSO model neuron receives synaptic inputs whose firing rate functions are stored in the input directory, e.g., "C:/Neuron/LSO/input". The simulation results are saved in the output directory, e.g., "C:/Neuron/LSO/output". Two Matlab scripts in the model package, func_current_stim.m and func_syn_stim.m, provide example commands for data importing and plotting. System Requirements: NEURON program. Please refer to the general NEURON documentation ( for furtherinstructions on compiling mod files and launching hoc files on different operating systems. Matlab software (

C: Model Descriptions

Cell Model: An LSO cell was simulated using a modified leaky integrate-and-fire (LIF) model containing a capacitance Cm, a leak conductance GL, and two time-varying conductance-based channels, Gabs and gAHP(t), which produced the absolute and relative refractory periods, respectively, for a model cell. After the absolute refractory period (t_abs), the conductance of the adaptation channel gAHP(t) was increased by GAHP and decayed exponentially toward zero with a time constant tau_AHP. Responses of four model cells were tested in modeling, which have small or large GAHP and short or long tau_AHP. (See Table I in Zhou and Colburn, 2010.) Input Model: Stimulation was provided through either current injection (which simulated the ipsilateral-alone stimulation) or through synaptic-conductance channels (which simulated the combined effects of ipsilateral and contralateral acoustic stimulation).

D: Simulations

Example test 1: Stochastic current injection

Run LSO_current_input.hoc to launch the screen below. The command and parameter panels are shown on the left and the three result panels are shown on the right. On the parameter panels, shown from the top to bottom shown the leak conductance, Gabs and t_abs, AHP channel, and injecting current properties. Specify the AHP channel and current properties. The default setting is those of the model cell 4 (GAHP =0.08uS and tau_AHP=5ms). The default current input has I_mean of 1.4nA and sigma_I of 0.4nA. The values of passive leak conductance and absolute refractory period (2ms) were those reported in Zhou and Colburn (2010). Hit Run. Shown on the middle result panel is the PSTH, and those on the right from top to bottom are the recovery function, the inter-spike interval histograms of the steady state of responses (>40 msec), the serial dependence of GAHP, and the serial dependence of interspike intervals. Methods of data analyses are given in Zhou and Colburn (2010). Hit WriteFile, which saves eight data files into the subfolder /output. Each file was named after AHP channel and input current parameters. Run Matlab script func_current_stim.m, which plots the results of all 4 model cells in response to current stimulation with I_mean =1.4nA and sigma_I = 0.4nA. screenshot 1

Example test 2: Synaptic stimulation with binaural EI inputs

Run LSO_synaptic_input.hoc to launch the screen below. Main procedures are identical to the program shown above. The default setting used the model cell 1 (GAHP =0.02 uS and tau_AHP=20 ms). The peak conductance of excitatory (Ge) and inhibitory (Gi) conductance are 3ns and 1.2ns, respectively. This setting yields a net zero synaptic current at the spiking threshold (i.e., balanced excitation and inhibition). See Methods in Zhou and Colburn (2010) for more details. To specify an ILD, click Choose E Input Rate and then choose from the pull-down menu a desired ipsilateral (excitatory) sound level. Do the same for contralateral (inhibitory) sound level. Hit Run. The results shown on the screen were obtained by using E=50dB and I=10dB. Hit WriteFile, which saves eight data files into the subfolder /output. Each file was named after AHP channel and E/I level. The sound pressure level from 0 to 70dB are coded by letters A to H, respectively. Run Matlab script func_syn_stim.m, which plots the results of the 4 model cells in response to binaural inputs with E=50dB and I=10dB. screenshot 2


Tsuchitani C, Johnson DH (1985). The effects of ipsilateral tone burst stimulus level on the discharge patterns of cat lateral superior olivary units. J Acoust Soc Am 77: 1484-1496. Zhou Y and Colburn HS (2010). "Effects of membrane afterhyperpolarization on discharge interval statistics: A model study of responses of lateral superior olive neurons to ipsilateral and bilateral acoustic stimuli," J. Neurophysiol. 103: 2355-2371.


Yi Zhou (zhouyi at