diff --git a/README.md b/README.md new file mode 100644 index 0000000..87ed7e9 --- /dev/null +++ b/README.md @@ -0,0 +1,22 @@ +# Bruce A. Carlson and Masashi Kawasaki +**Stimulus Selectivity Is Enhanced by Voltage-Dependent Conductances in Combination-Sensitive Neurons** +*J Neurophysiol* 96: 3362–3377, 2006. + +## Abstract + +Central sensory neurons often respond selectively to particular combinations of stimulus attributes, but we know little about the underlying cellular mechanisms. The weakly electric fish *Gymnarchus* discriminates the sign of the frequency difference (Df) between a neighbor’s electric organ discharge (EOD) and its own EOD by comparing temporal patterns of amplitude modulation (AM) and phase modulation (PM). Sign-selective neurons in the midbrain respond preferentially to either positive frequency differences (Df > 0 selective) or negative frequency differences (Df < 0 selective). + +To study the mechanisms of combination sensitivity, we made whole cell intracellular recordings from sign-selective midbrain neurons in vivo and recorded postsynaptic potential (PSP) responses to AM, PM, Df > 0, and Df < 0. Responses to AM and PM consisted of alternating excitatory and inhibitory PSPs. These alternating responses were in phase for the preferred sign of Df and offset for the nonpreferred sign of Df. Therefore a certain degree of sign selectivity was predicted by a linear sum of the responses to AM and PM. + +Responses to the nonpreferred sign of Df, but not the preferred sign of Df, were substantially weaker than linear predictions, causing a significant increase in the actual degree of sign selectivity. By using various levels of current clamp and comparing our results to simple models of synaptic integration, we demonstrate that this decreased response to the nonpreferred sign of Df is caused by a reduction in voltage-dependent excitatory conductances. This finding reveals that nonlinear decoders, in the form of voltage-dependent conductances, can enhance the selectivity of single neurons for particular combinations of stimulus attributes. + +## Usage + +The archive has all the Matlab files needed to run the conductance-based models from our *J Neurophysiol* paper. + +- **sinecond_model** models the effects of excitatory and/or inhibitory synaptic responses to modulation of a single stimulus feature under a variety of holding currents, with or without active conductances (`leak_int_act.m` or `leak_int.m`, respectively). +- **sinecond_model_2input** models the effects of excitatory and/or inhibitory synaptic responses to modulation of 2 different stimulus features, with or without active conductances. + +--- + +2025-05-27 – Standardized to Markdown \ No newline at end of file diff --git a/readme.txt b/readme.txt deleted file mode 100644 index 60d4753..0000000 --- a/readme.txt +++ /dev/null @@ -1,47 +0,0 @@ -This is the readme for the model associated with the paper: - -Bruce A. Carlson and Masashi Kawasaki -Stimulus Selectivity Is Enhanced by Voltage-Dependent Conductances -in Combination-Sensitive Neurons -J Neurophysiol 96: 3362–3377, 2006. - -Abstract: - -Central sensory neurons often respond selectively to particular -combinations of stimulus attributes, but we know little about the -underlying cellular mechanisms. The weakly electric fish Gymnarchus -discriminates the sign of the frequency difference (Df) between a -neighbor’s electric organ discharge (EOD) and its own EOD by comparing -temporal patterns of amplitude modulation (AM) and phase modulation -(PM). Sign-selective neurons in the midbrain respond preferentially -to either positive frequency differences (Df >0 selective) or negative -frequency differences (Df <0 selective). To study the mechanisms of -combination sensitivity, we made whole cell intracellular recordings -from sign-selective midbrain neurons in vivo and recorded postsynaptic -potential (PSP) responses to AM, PM, Df >0, and Df <0. Responses to -AM and PM consisted of alternating excitatory and inhibitory -PSPs. These alternating responses were in phase for the preferred sign -of Df and offset for the nonpreferred sign of Df. Therefore a certain -degree of sign selectivity was predicted by a linear sum of the -responses to AM and PM. Responses to the nonpreferred sign of Df, but -not the preferred sign of Df, were substantially weaker than linear -predictions, causing a significant increase in the actual degree of -sign selectivity. By using various levels of current clamp and -comparing our results to simple models of synaptic integration, we -demonstrate that this decreased response to the nonpreferred sign of -Df is caused by a reduction in voltage-dependent excitatory -conductances. This finding reveals that nonlinear decoders, in the -form of voltage-dependent conductances, can enhance the selectivity of -single neurons for particular combinations of stimulus attributes. - -Usage: - -The archieve has all the Matlab files needed to run the -conductance-based models from our J Neurophysiol -paper. "sinecond_model" models the effects of excitatory and/or -inhibitory synaptic responses to modulation of a single stimulus -feature under a variety of holding currents, with or without active -conductances (leak_int_act.m or leak_int.m, respectively). -"sinecond_model_2input" models the effects of excitatory and/or -inhibitory synaptic responses to modulation of 2 different stimulus -features, with or without active conductances.