The phenomenologic model graphic editor is called P_neuron. P_neuron is an Xwindow graphic editor for the phenomenological neuron model of XNBC. It allows to choose the neuron parameters using sliding scales (on the right part and on the bottom of the screen) with visual feed back control in a graphic window displaying the unit membrane potential during an adjustable simulation duration (on the left part of the screen). Since many scales are available, they cannot be seen simultaneously on the screen. Scrollbars allows to shift the scales right and left (and up and down) to reach unvisible scales.
Three EPSP and three IPSP can be positionned using scales and moved dynamically as scales are moved. The EPSP and IPSP weight are adjustable separatately (but is the same for all three of each kind). They allow to make the neuron firing and to explore what happens when the weight changes (spike firing, IPSP, reversal potential approach, etc.). Equations are given in the Appendix B, Appendix C and Appendix D, as weel as the default values.
A menu bar with pulldown menus allow to cope with files, parameters and options.
Write Back Neuron: The parameter values are saved in a file with the .P_unit, .L_unit or a .B_unit extension according to the model worked on. This saves the file with the same as the previously read or saved file (if non name was given,This files can be read back by P_neuron ( File-Read Neuron) and other XNBC programs. P_neuron is the default name. according to the model worked on Save Neuron As...: The parameter values are saved in a file with the .P_unit, .L_unit or a .B_unit extension
This save the file with a new name that is asked using a file selection box. This files can be read back by P_neuron ( File-Read Neuron) and other XNBC programs. P_neuron is the default name.
Print: produces a PostScript hard copy file of the neuron membrane potential evolution, automatically spooled on the printer indicated by the PRINT_PLOT_PS environment variable. The output file file_in.P_unit.ps, file_in.L_unit.ps or file_in.B_unit.ps is spooled on the PostScript printer, and then deleted if the Keep PostScript files is not set on the control pannel.
Quit: exit the phenomenologic editor P_neuron.
Change Parameter: call back to front screen the two pannels with scales (if they were previously closed).
Redraw: redraws the neuron (if any X server problem).
Back to defaults: reload all the default parameters for scales. Scales are poitioned back to these values.
Static Update: When moving the scales positioning the 3 EPSP or the 3 IPSP, the neuron graph is updated dynamically. On slow or overloaded computers, this can be disturbing. Setting this option disable the dynamic update of these scales. Less Fatigue: The adaptation of the neuron is controled through the threshold increase after each spike. If no fatigue is set, the threshold increase is constant. This is controlled using the fatigue threshold scale. If fatigue is set, the threshold increase increases, proportinally to the scale value. Less Fatigue option modifies the algorithm used to modify the fatigue.
Scales allows to modify the vertical scale of the membrane potential representation.
Leaky Integrator allows to simulate the LIM model When this option is set, files read and written have the extension .L_unit.
Conditional Burster: allows to simulate a conditional burster (BUM), with two threshold: one threshold fires normal spike, while the other -generally above the first- starts a burst that stops only if an ipsp arrives, or if the predefined duration is over. The intra burst firing frequency is adjusted using scales, as well as a composition factor, a multiplying factor applied on the firing frequency when an epsp arrives during a burst. The corresponding scales are activated when this option is set. When this option is set, files read and written have the extension .B_unit.
The following vertical scales are always active and available:
The following scales are actives when the Conditional Burster option is set:
The following scale is active when the Noise Filter option is set:
The following horizontal scales are always active and available:
The following scales are active for the PUM and the BBUM
P_neuron produces a PostScript file file_name_P_unit.ps that prints the membrane potential. It is automatically spooled and deleted. Files can be kept if the Keep PostScript pushbutton of the XNBC control panel is set.
The parameters of the neuron can be saved in a file whose extension is .P_unit or .B_unit. The file produced can be read back by P_neuron (and related programs, as XNBC V8 [7]).
To read a neuron, choose in the menu bar the [File] popdown menu, and the [Read neuron] pushbutton. A file selection box will pop up to give a name. No extension is needed, it is added to the name automaticaly. If changing parameters, further savings can be done using the [Write neuron back...] pushbutton in the [File] popdown menu. It is a prudent habit to save regularly his work. If no file was read previously, and thus no name was given previously, the file selection box will pop up to give a name.
To save a neuron, choose in the menu bar the [File] popdown menu the [Save neuron as...] pushbutton. A file selection box will pop up to give a name. No extension is needed, it is added to the name automaticaly. When a name has been given, the [OK] pushbutton saves the neuron. Consequently, further savings can be done using the [Write neuron back...] pushbutton in the [File] popdown menu. It is a prudent habit to save regularly his work.
When exiting, and if a parameter has been changed after the last saving operation, a message warns the user that the file was not saved, and allows to return to the program to normally save the neuron.
Input files: file_in.P_unit, file_in.L_unit, file_in.B_unit
Output files: file_in.P_unit, file_in.L_unit, file_in.B_unit, file_in.P_unit.ps, file_in.L_unit.ps, file_in.B_unit.ps.
Self explaining diagnostics are provided on errors.
