Exercises

1. If you use the -hsolve option of readcell, why does it make good sense not to call the SETUP action after the readcell command has been completed. This means that you always have to manually call the SETUP action to get everything work.
2. About the demo for interfacing to an efield element:
   1. How can you be sure that indeed two plots have been created?
   2. Add a plot for the conductance of a channel.
   3. Add an xcell display. You should know that this can be done in two different ways (which ones ?). Implement these two methods and try to figure out if there is a performance difference.
3. Examine the Purkinje cell tutorial that comes with the Genesis distribution. Try to understand the different experiments that can be done with the tutorial.
   1. The tutorial supports two different protocols for current injection: (1) a constant current and (2) a pulsed current via the use of the pulsegen object. Is this invisible to hsolve? Why? It is possible to switch the current on or off during the simulation. How is that made possible?
   2. Find and examine the code to update the frequency field of synaptic channels (you have to know the actions HSAVE and HRESTORE, but the comments in the code clarify what they are supposed to do). How efficient or inefficient is this implementation? Can this be implemented with a script_out element? Would that make any difference?
   3. It is possible to synchronously activate synaptic channels of the Purkinje cell (via the synapses of the parallel fibers). Examine how the code is organized to implement this functionality.
   4. The climbing fiber gives excitatory input to the Purkinje cell at different locations, with various time delays. Examine the implementation of the time delay.
   5. The code that links the membrane potential of the excitatory currents with the xcell element uses findsolvefield. Examine the Genesis element hierarchy to locate the elements that are the original sources for the messages (not hsolve). What is peculiar in this use of findsolvefield?
4. Improve the example for the DUPLICATE action:
   1. Create a second population, let's say 10 cells. You could use the multi-compartmental cell that is used for the single cell part of this tutorial. Create connections between the populations (when do you have to create these connections and how does this restriction propagate to your Genesis script?). Create hsolve elements for both populations.
   2. Add input to the network with a population of randomspike elements.
   3. Add output to the network: plot some of the membrane potentials (use findsolvefield).

NOTE: The examples as well as the exercises originate from scripts that have been used for scientific research. These scripts are available from http://www.bbf.uia.ac.be/