Visual DMS simulation

The following tutorial will show you how to install LSNM and perform a visual Delayed Match-to-Sample (DMS) simulation. As shown in the figure below, the DMS experiment to be simulated consists of a visual stimulus (S1) being presented to a subject, followed by a delay period during which time no stimulus is presented. At the end of the delay period, a second visual stimulus (S2) is presented to the subject, after which the subject must respond whether S1 and S2 are the same or different (Response).

Because the input module to our visual neural network (LGN) is composed of 81 units in the form of a 9x9 matrix, we need to organize our visual inputs in a 9x9 grid. We will initialize the units of our grid to zero and, in order to turn on selected units within the grid, we will assigning values of 0.92 to those units. For this tutorial, we will make use of inputs representing two-dimensional object shapes, all of them arranged in 9x9 grids and located in the script [visual_model/script_to_replicate_Horwitz_2005_Fig_3.py] (https://github.com/NIDCD/lsnm_in_python/blob/master/visual_model/script_to_replicate_Horwitz_2005_Fig_3.py) (This script replicates Figure 3 of [Horwitz et al, 2005] (http://www.ncbi.nlm.nih.gov/pubmed/16087450)).

In this tutorial, we will simulate one single trial.

NOTE: If you already have a working copy of LSNM, go directly to STEP 2

1. Download a copy of LSNM to your local workstation

• Launch Firefox or another web browser available on your local Unix workstation and copy/paste the following internet address (or just click on the highlighted link if you are in a browser already): https://github.com/NIDCD/lsnm_in_python.

• When the LSNM Github page displays, click on the button Download ZIP located on the right sidebar. Click on Save File to download the zip file containing the LSNM code to your Downloads folder.

• Inspect your downloads folder to make sure you have downloaded the LSNM files. There should be a file called lsnm-master.zip in it.

• Unzip the file in your preferred location:

    $ unzip lsnm-master.zip
  

• Change the name of the lsnm directory (to keep the sim executable from having problems with the special character -:

    $ mv lsnm-master lsnm
  

• NOTE: If you do not have access to an internet browser you can grab a copy of the LSNM repository by typing the following command on your local Unix workstation. Please note that at a directory called sim will be created in the directory where you are currently located:

    $ git clone https://github.com/NIDCD/lsnm_in_python.git
  

2. Move to a directory that contains simulated subject input data:

    $ cd lsnm_in_python/visual_model/subject_11

3. Make a directory called 'tutorial' and move to it

    $ mkdir tutorial
    $ cd tutorial

4. Now execute the simulator:

    $ python2.7 ../../../simulations/sim.py &

A GUI window will be displayed on the screen.

Images/simulator_GUI.png

Please select your model as [visual_model/model.txt] (https://github.com/NIDCD/lsnm_in_python/blob/master/visual_model/model.txt) in the "Model Descrition File" field, your weights as [visual_model/subject_11/weightslist.txt] (https://github.com/NIDCD/lsnm_in_python/blob/master/visual_model/subject_11/weightslist.txt) in the "Weights List File" field, and your script as [visual_model/script_to_replicate_Horwitz_2005_Fig_3.py] (https://github.com/NIDCD/lsnm_in_python/blob/master/visual_model/script_to_replicate_Horwitz_2005_Fig_3.py) in the "Simulation script File" field.

Do not select the "TVB" or "Generate new user" at this point.

Now, press the "Run" button.

5. Plot your output:

    $ python2.7 ../../../plot_neural_visual.py &

After which you should be able to see the following plot: