Chapter 7. Programming Simulations

7.4 SYNAPTIC ASSIGNMENTS

1. By Program

Assignments of synaptic parameters can be made in the original hoc program as shown in the box below. Frequently they may need to be adjusted (by experimenting) for a particular condition and then saved in a "session". Default synaptic parameter values (noted in box below) are overwritten by program statements and these in turn may be overwritten by the values stored in sessions. The default values for a particular session become those assigned at the time of saving a session. Check marks show up in the session parameter panels only after values have been changed since the last retrieval.

Box 4. synapses.hoc 


    objvar syn[#]	// defines numberof synapses to be used

    soma syn[0]=newAlphaSynapse(locsyn[0])
			// defines fitst synapse as to type
				 and location
		// Alpha Synapse parameter default values are:
		// reversal potential (e = 0);  gmax = 0;
		// tau = 0; onset = 0
		// if different values are desired, define
		// by statements as  below with the chosen 
		// value entered on the right side of eq.
    sny[0].e =
    sny[0].gmax =
    sny[0].tau =
    sny[0].onset =

2. By Point Process Manager

Alpha synapses may also be created and placed in any section pressing the
  1. "Point Processes" button on the main menu, choosing
  2. "Managers" followed by
  3. "Point Manager" . Then, upon pressing
  4. "Select Point Process" on the new panel, and choosing
  5. "AlphaSynapse" from the list of available point processes
an AlphaSynapse will be placed in the center of the currently" accessed" section.
Here the "Shape" is shown in the lower part of the panel. The location of the synapse is indicated by the position of Blue circle on dendrite, and that dendrite is shown in RED to indicate the section accessed. The location of the synapse may be changed readily by "clicking" anywhere on any section. The Blue circle will jump there, the new section will be shown in RED ,and the precise location in the active compartment will be updated in upper part of the panel. Dismissing the window will remove the point process from the cell and destroy it.

Viewing and modification of assigned AlphaSynapse parameters

Viewing of synaptic parameters, whether defined by program as above in Chapter 7.1 or by the Point Process manager, is made possible by pressing the
  • "Point Processes" button on the main menu and choosing
  • "Viewers" followed by
  • "Point Processes". Then, upon choosing
  • "AlphaSynapse" from the list of available point processes,
  • This will bring up a Browser panel showing all of the currently assigned AlphaSynapses. "Double clicking" on one or all of these will bring up AlphaSynapse parameter panels.
    This whole process is encapsulated in the figure below.

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