GENESIS Turtle Cortex Model README file
This is the large scale model of turtle visual cortex (the "NGU model")
Nenadic, Z., Ghosh, B.K. and Ulinski. P. (2003)
Propagating Waves in Visual Cortex: A Large Scale Model of Turtle Visual
Cortex", J. Computational Neuroscience 14:161-184.
Nenadic, Z., Ghosh, B.K. and Ulinski. P. (2002) Modeling and Estimation
Problems in the Turtle Visual Cortex, IEEE Trans. Bio-Med. Eng., 49:753-762
It is also described in considerable detail in the file
TurtleVisCortex-descrip.pdf, which is included in this archive.
This README file tells how to run the simulation with GENESIS.
To run the simulation
1. If you do not have the GENESIS simulator installed, download it from
the GENESIS web site at http://genesis-sim.org/GENESIS. It is available
in source and binary versions for UNIX/Linux, MAC OSX, and Windows with
Cygwin. Follow the installation instructions provided with the
2. Unpack the archive TurtleVisCortex.tar.gz or TurtleVisCortex.zip.
It will unpack to the directory TurtleVisCortex/.
3. In a console window, change to the directory TurtleVisCortex/models
4. Start genesis
5. In genesis, type "TurtleVisCortex"
With the default settings in the main simulation script
TurtleVisCortex.g, a simple graphical interface appears, after a few
minutes of setup time for the network. It's use is optional, and the
main script may be modified to perform the simulation with no graphics,
as for doing long simulation runs in batch mode. In either case, output
is generated to plain text files in subdirectories of TurtleVisCortex/output.
6. Click on RUN in the CONTROL PANEL
The default stimulus applied is the "diffuse light flash", simulated
with a 0.15 sec pulse of 0.2 nA injection current to the soma of all 201
LGN neurons. The four graphs show the network response by plotting the
soma membrane potential of the medial and lateral layer pyramidal cell
neurons /network_lateral/cell321, /network_medial/cell279,
/network_lateral/cell1, and /network_medial/cell1. The window under the
control panel shows the locations of the lateral (represented by
squares) and medial (represented by triangles) pyramidal cells. During
the simulation, they change color to represent the soma membrane
potenial of the cells cells. For the first 0.6 seconds of the
simulation, you will see the spreading wave of activation, due to the
Further notes on the simulation scripts
The TurtleVisCortex.g script includes various GENESIS scripts in ../lib
that define functions that are used in the main script for setting up
the network. It defines several global variables that may be changed to
alter the simulation behavior. Some of the more important ones are:
Simulation duration and integration step size in seconds:
float tmax = 1.50 // Time in seconds for the simulation to run
float dt = 0.00005 // Internal time stepsize
The stimulation flags:
int DIFFUSE_LIGHT_FLASH = 1
int STATIONARY_LIGHT_SPOT = 0
int MOVING_LIGHT_SPOT = 0
int DIRECT_NEURON_STIM_REC = 0
int DIRECT_NEURON_STIM_CIR = 0
These are for
1. Diffuse light flash (the default)
2. Stationary spot flash
3. Moving spot stimulation
4. Direct neuron stimulation -- rectangular area
5. Direct neuron stimulation -- circular area
The functions can be used individually, or in combinations. In fact, you
can stimulate all five ways in the same run if you want to. Details for
changing the stimulus are provided in TurtleVisCortex.g and in
The default name of the data directory for the output response files is
defined in TurtleVisCortex.g as:
str responseName = "TurtleVisCortex_diffuse_"
Change this name for each different run. If files in a directory with
this name exist, they will be overwritten the next time the simulation
../lib/utilities_control.g defines the functions that are used to run
the simulation with or without graphics. It can be used as the starting
point for more sophisticated graphical interfaces to the simulation.
../coords contains plain text data files with the coordinates
of neurons in the seven layers of the model. The figure in
TurtleVisCortex/coords/Distribution_of_Neurons_Cortex.pdf shows the
locations of the 368 lateral neurons (blue), 311 medial neurons
(yellow), 20 horizontal neurons (green), 45 stellate neurons (red), and
44 subpial neurons (magenta) in a simulated 1.6 x 1.6 mm piece of
cortex. There are also 201 LGN input neurons, represented as a line of
equally spaced cells.
Displaying simulation results with DAVIS
Davis (Data Viewing System) is a general-purpose data viewer designed
for the simultaneous display of a large number of dynamic data sets.
Davis was inspired by the need to explore computational models of the
cerebral cortex, and may be used to provide a variety of visualizations
of the output from this model.
You may find more about Davis from http:/visual.cs.utsa.edu/davis/
and instructions for using webstart to run it directly from a browser
in order to further analyze the output of this model.