Attractor Bump Simulation
This is an interactive simulation of an attractor bump, written in Matlab.
Feel free to download the zip file, or just browse the source code.
To run this software:
- Start up Matlab.
- cd to the directory containing this code, e.g.,
in the Matlab command window you would type:
>> cd myfiles/bump/code
- Type "bump" in the Matlab command window.
For more information, see:
- The "Run" button puts the model in continuously-running mode.
The "Step" button puts it in single-step mode and runs for 1 step.
- Mouse click anywhere in the plot area to supply external input.
Mousing on the flank of the bump causes the bump to shift.
- The "Bias" slider adds a constant bias term to every unit, which
has a multiplicative (not additive!) effect on the bump.
- The "Noise" slider adds random noise into the activation levels
of all units.
- The SemiLinear/Tanh pulldown menu allows you to switch between units
with a semilinear vs. tanh output function. It automatically adjusts
various parameter values to assure a well-formed, stable bump in each
- The "Input Hold" toggle is used to apply a constant external input.
Turn it on, then mouse click anywhere in the graph to apply an input.
The model can be in either Run or Step mode. To remove the external
input, turn off the toggle and put the model in Run mode; the input
will decay back to zero.
Touretzky, D. S. (2005) Attractor network models of head direction
cells. In. S. I. Wiener and J. S. Taube (Eds.), Head Direction
Cells and the Neural Mechanisms Underlying Directional
Orientation, pp. 411-432. MIT Press.
Funded in part by National Institutes of Health MH 59932.
Last modified: Fri Feb 2 00:32:09 EST 2007