SOME EXERCISES TO ACCOMPANY THE SQUID TUTORIAL

1) Perform a simulation of a voltage clamp experiment using the default
   parameters for the voltage clamp mode.  Explain the features in the plot
   of total injection current and relate them to the channel current plots.

2) Perform a voltage clamp experiment to estimate the sodium reversal
   potential.

3) In their experiments on the giant squid axon, Hodgkin and Huxley found
   that the sodium inactivation was completely removed for voltages more
   than 40 mV below the resting potential and that the sodium channels were
   completely inactivated for voltages 40 mV above the resting potential.
   At the resting potential, the steady-state inactivation parameter, h, is
   about 0.6.  Perform a two-step voltage clamp experiment using pre-pulses
   (conditioning pulses) of -40, 0, and +40 mV to reproduce these results.

4) In Current Clamp mode, set the injection current (Pulse 1 Current) to
   zero.  Now increase the external potassium concentration [K] until
   spontaneous oscillations occur.  Why does the increased level of [K]
   cause oscillations?  Do you expect similar results to occur when [Na]
   is varied?