| || Models ||Description|
Excitability of the soma in central nervous system neurons (Safronov et al 2000)
||The ability of the soma of a spinal dorsal horn neuron, a spinal ventral horn neuron, and a hippocampal pyramidal neuron to generate action potentials was studied using experiments and computer simulations. By comparing recordings ... of a dorsal horn neuron with simulated responses, it was shown that computer models can be adequate for the study of somatic excitability. The modeled somata of both spinal neurons were unable to generate action potentials, showing only passive and local responses to current injections. ... In contrast to spinal neurons, the modeled soma of the hippocampal pyramidal neuron generated spikes with an overshoot of +9 mV. It is concluded that the somata of spinal neurons cannot generate action potentials and seem to resist their propagation from the axon to dendrites. ... See paper for more and details.
Spike frequency adaptation in spinal sensory neurones (Melnick et al 2004)
||Using tight-seal recordings from rat spinal cord slices, intracellular
labelling and computer simulation, we analysed the mechanisms of spike
frequency adaptation in substantia gelatinosa (SG)
neurones. Adapting-firing neurones (AFNs) generated short bursts of
spikes during sustained depolarization and were mostly found in
lateral SG. ... Ca2 + -dependent conductances do not contribute to
adapting firing. Transient KA current was small and completely
inactivated at resting potential suggesting that adapting firing was
mainly generated by voltage-gated Na+ and delayed-rectifier K+ (KDR )
currents. ... Computer simulation has further revealed that
down-regulation of Na+ conductance represents an effective mechanism
for the induction of firing adaptation. It is suggested that the
cell-specific regulation of Na+ channel expression can be an important
factor underlying the diversity of firing patterns in SG neurones.
See paper for more and details.
Tonic firing in substantia gelatinosa neurons (Melnick et al 2004)
||Ionic conductances underlying excitability in tonically firing neurons
(TFNs) from substantia gelatinosa (SG) were studied by the patch-clamp
method in rat spinal cord slices. ... Suppression of Ca2+ and KCA currents ... did not
abolish the basic pattern of tonic firing, indicating that it was
generated by voltage-gated Na+ and K+ currents. ...
on the basis of present data, we created a model of TFN
and showed that Na+ and KDR currents are sufficient to generate a
basic pattern of tonic firing. It is concluded that the balanced
contribution of all ionic conductances described here is important for
generation and modulation of tonic firing in SG neurons. See paper for more and details.