Model of Bee Foraging

1. Sensory Input Nectar S Y N B Action R WN WY WB r(t) δ(t) P Based on Predictive Hebbian Learning Model of Bee Foraging Iain Black Simply put, learning in our brains takes place by changing the strength of connections between individual neurons. How the connection strengths are set depends on the learning rules. Artificial neural networks work in this way too, and many different learning rules have been developed for learning different tasks. The aim of this project is to investigate the operation of a learning rule that is biologically plausible - predictive Hebbian learning. The idea is to implement a simple neural network that models the behaviour of a bee foraging for nectar in a field of flowers, based on the work of Montague et al. (Nature 377:725-728, 1995). This simulator will allow an investigation of how the bee's behaviour is influenced by the learning parameters of the model. The bee will fly around a field of blue and yellow flowers and hope to get a reward (quantity of nectar) for each flower it lands on. However there is a catch! The bee will be rewarded with 2uL nectar for yellow flowers and 6uL for blue flowers, however, there is only a 1/3 chance the blue flowers will have this reward. With the rewards the same overall, what will the bee choose? START RANDOMLY POSITION BEE AT TOP OF ARENA WITH RANDOM INITIAL HEADING NO HAS BEE LANDED? YES REPEAT The above diagram shows the structure of the artificial neuron that is used to model the bee’s decision making. The bee will receive sensory inputs of yellow, neutral (out of field) and blue which represents the bee’s vision. Depending on the bee’s previous experience (i.e., constant reward failure from blue flowers), it will make a decision to continue on it’s path or re-orientate to try and find a more favourable part of the field. RECEIVE OUTPUT OF P GET (OR NOT) NECTAR FROM FLOWER NO REORIENTATION UPDATE SENSORY WEIGHTS REORIENTATON MAKE RANDOM CHANGE IN HEADING AND TAKE A STEP RESTART CONTINUE ON PATH BY 1 STEP The flowchart shows the basic decisions the bee must make during it’s foraging. This sequence is repeated for a desired number of times, a pattern should emerge. The bee will move around the field attempting to forage nectar in an efficient manner. The slider represents the percentage of blue/yellow the bee is viewing at the current time. The bee should tend to favour one colour over the other. Different learning rules should provide different results.