UA Dr. Robert Legenstein, WiMAus Prashant Joshi, M.S.
Institute for Theoretical Computer Science
Technische Universität Graz
A-8010 Graz, Austria
In this exercise you will investigate how inhibition can be useful for enhancing contrast in the input. For this exercise too, you will use the CSIM tool.
You have excitatory neurons , topologically arranged into a circle, and inhibitory neurons , which are also arranged in a cirle on a plane parallel to the plane which has excitatory neurons. Each excitatory neuron , is connected to the corresponding inhibitory neuron , through an excitatory synapse. Each inhibitory neuron, inhibits the neighbours of its corresponding excitatory neuron, in a certain inhibition radius, . For example if the inhibition radius , then the inhibitory neuron will make inhibitory synapses to excitatory neurons and (in wrap-around configuration). The external input is applied to the excitatory neurons. The external input to any neuron is a current of constant magnitude.
Given this setup, the firing rate of neuron will show a definite peak, if the neurons , recieve a constant input current and neurons recive a constant input current of magnitude , where .
Figure 1 shows the experimental setup for a linear arrangement of neurons.
In your code define the following variables:
For each of the experiments given below, you are required to submit a plot with four panels. The first panel of the plot will show the input stimulus (x axis - neuron index, Y axis - the magnitude of stimulus). The second panel will show the firing rate of the excitatory neurons (X axis - neuron index, Y axis - firing rate). Panel 3 and 4 will show the spike rasters over time for the excitatory and inhibitory neurons respectively (X axis - time, Y axis - spike rasters for neurons 1 to ).
This document was generated using the LaTeX2HTML translator Version 2002-2-1 (1.70)
Copyright © 1993, 1994, 1995, 1996,
Computer Based Learning Unit, University of Leeds.
Copyright © 1997, 1998, 1999, Ross Moore, Mathematics Department, Macquarie University, Sydney.
The command line arguments were:
latex2html -split=0 -no_navigation ex6.tex
The translation was initiated by Joshi Prashant on 2006-05-16