CS 420/527 — Biologically Inspired Computation
NetLogo Simulation

Hopfield Update Demonstration

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view/download model file: Hopfield-update.nlogo

WHAT IS IT?

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HOW IT WORKS

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HOW TO USE IT

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THINGS TO NOTICE

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THINGS TO TRY

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EXTENDING THE MODEL

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NETLOGO FEATURES

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RELATED MODELS

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CREDITS AND REFERENCES

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PROCEDURES

breed [centrals central]
breed [neurons neuron]
undirected-link-breed [connections connection]

centrals-own [ state local-field ]
neurons-own [ state ]
connections-own [ weight ]

to setup
 ca
create-centrals 1
create-neurons 10
ask centrals 
 [ set size 3
randomize-state
set local-field 0
create-connections-with neurons
[ initialize-connections ]
]
layout-radial neurons connections (central 0)
 ask neurons [ initialize-neurons ]
end
to initialize-neurons
 set size 2
randomize-state
show-state
end
to randomize-state
 set state 2 * random 2 - 1
show-state
end
to initialize-connections
 randomize-weight
end
to randomize-weight
 set weight random-float 20 - 10
ifelse weight > 0 
 [ set color scale-color red weight -10 20 ] [
 ifelse weight < 0 
 [ set color scale-color blue weight 10 -20 ]
 [ set color grey ]]
 set label round (10 * weight) / 10
end
to show-state
 ifelse state > 0
[ set color red set heading 0 ]
 [ set color blue set heading 180 ]
end
to calculate-local-field
 ask centrals [
 set local-field sum [partial-field] of neurons
 ]
 ask patches ; with [(abs pxcor) + (abs pycor) < 10]
[
let LF [local-field] of central 0
ifelse LF > 0
[ set pcolor scale-color red (LF / (pxcor ^ 2 + pycor ^ 2 + 1)) 0 20 ]
 [ set pcolor scale-color blue (LF / (pxcor ^ 2 + pycor ^ 2 + 1)) 0 -20 ]
 ]
end
to-report partial-field
 report state * [weight] of connection-with central 0
end
to update-central
 ask centrals [
 ifelse local-field > 0
[ set state 1 ]
 [ set state -1 ]
 show-state
 ]
end