HH channel and negative inject current

[reza_rzm]

Dear Freinds,

In toturial Neuron file, sThA.hoc is a code for a simple soma with HH channel ,that we inject current (IClamp) in soma. for a current with amp=0.1 i see a train of spikes durring the current injection.

But, for amp=-0.1 again i see one spike in end of pulse,!!!!

this spike is similar to low thershold Ca spike that we see in another cod of tutorial sThD.hoc . in this code we insert CaT channel in soma as well as HH channel.

i guess it should be some misudrestanding. from HH model?

or is it somthing else in Neuron?

I await for your reply! Thank's in advance

[ted]

Without playing with the model you mention, my guess is that you are seeing
something that is called rebound spiking, or anode break excitation. This is an
interesting property of many kinds of excitable tissue, and you will find it described
and explained in standard neuroscience textbooks. You might also try googling
any of these phrases or their variants:
rebound spike (or rebound spiking)
rebound excitation
anode break
anode-break