2D RepresentationΒΆ

Purpose: This demo shows how to construct and manipulate a population of 2D neurons.

Comments: These are 100 leaky integrate-and-fire (LIF) neurons. The neuron tuning properties have been randomly selected to encode a 2D space (i.e. each neuron has an encoder randomly selected from the unit circle).

Usage: Grab the slider controls and move then up and down to see the effects of shifting the input throughout the 2D space. As a population, these neurons do a good job of representing a 2D vector value. This can be seen by the fact that the input graph and neurons graphs match well.

Output: See the screen capture below. The ‘circle’ plot is showing the preferred direction vector of each neuron multplied by its firing rate. This kind of plot was made famous by Georgoupolos et al.

../_images/2drepresentation.png
Code:
import nef

net=nef.Network('2D Representation')  # Create the network

net.make_input('input',[0,0])         # Create a controllable 2-D input
                                      # with a starting value of (0,0)
                                      
net.make('neurons',100,2)             # Create a population with 100 neurons
                                      # representing 2 dimensions
                                      
net.connect('input','neurons')        # Connect the input to the neurons
net.add_to_nengo()

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