We present a new method for using genetic algorithms and L systems to grow
up efficient neural network structures. Our L rules operate directly on 2-d
imensional cell matrix, L, rules are produced automatically by genetic algo
rithm and they have "age" that controls the number of firing times, i.e., t
imes we can apply each rule. We have modified the conventional neural netwo
rk model so that it is easy to present the knowledge by birth (axon weights
) and the learning by experience (dendrite weights). A connection is shown
to exist between the axon weights and learning parameters used e.g., in bac
k propagation. This system enables us to find special structures that are v
ery fast for both to train and to operate comparing to conventional, layere
d methods.