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.
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.
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.