Pyramidal neurons: IKHT offsets activation of IKLT to increase gain (Fernandez et al 2005)

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Accession:48506
This matlab model was supplied by Dr Fernandez. It provides the model specification for the below paper. The influence of a high threshold K current on low threshold K and Na currents (especially frequency-current relationships) are studied in the paper with both experiments and modeling. Please see the reference for more and details.
Reference:
1 . Fernandez FR, Mehaffey WH, Molineux ML, Turner RW (2005) High-threshold K+ current increases gain by offsetting a frequency-dependent increase in low-threshold K+ current. J Neurosci 25:363-71 [PubMed]
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Model Information (Click on a link to find other models with that property)
Model Type:
Brain Region(s)/Organism:
Cell Type(s): ELL pyramidal cell;
Channel(s): I Na,t; I K; I Potassium; I_KHT; I_KLT;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: MATLAB;
Model Concept(s): Activity Patterns; Ion Channel Kinetics;
Implementer(s): Fernandez FR [ffernand at ucalgary.ca]; Mehaffey WH ;
Search NeuronDB for information about:  I Na,t; I K; I Potassium; I_KHT; I_KLT;
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IKHToffsetsIKLT
readme.txt
PyrMODEL.m
                            
Readme.txt for the model associated with the paper:


    Fernandez FR, Mehaffey WH, Molineux ML, Turner RW.
    High-threshold K+ current increases gain by offsetting a frequency-dependent
    increase in low-threshold K+ current.
    J Neurosci. 2005 Jan 12;25(2):363-71.


    Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada T2N 4N1. 
    ffernand@ucalgary.ca

Astract:
    High-frequency firing neurons are found in numerous central systems, including the auditory 
    brainstem, thalamus, hippocampus, and neocortex. The kinetics of high-threshold K+ currents 
    (IK(HT)) from the Kv3 subfamily has led to the proposal that these channels offset cumulative 
    Na+ current inactivation and stabilize tonic high-frequency firing. However, all high-frequency 
    firing neurons, examined to date, also express low-threshold K+ currents (IK(LT)) that have 
    slower kinetics and play an important role in setting the subthreshold and filtering properties 
    of the neuron. IK(LT) has also been shown to dampen excitability and is therefore likely to 
    oppose high-frequency firing. In this study, we examined the role of IK(HT) in pyramidal cells 
    of the electrosensory lobe of weakly electric fish, which are characterized by high-frequency 
    firing, a very wide frequency range, and high levels of IK(HT). In particular, we examined the 
    mechanisms that allow IK(HT) to set the gain of the F-I relationship by interacting with another 
    low-threshold K+ current. We found that IK(HT) increases the gain of the F-I relationship and 
    influences spike waveform almost exclusively in the high-frequency firing range. The frequency 
    dependence arises from IK(HT) influencing both the IK(LT) and Na+ currents. IK(HT) thus plays a 
    significant role in stabilizing high-frequency firing by preventing a steady-state accumulation 
    of IK(LT) that is as important as preventing Na+ current inactivation.

Usage note:
    If you comment out the lines that have "butter" and "nsb" and then remove the comment for 
    one of the other I(j,k) assignment statements, then you can run the model code without 
    the signal processing toolbox.