We describe an analytical framework for the adaptations of neural systems t
hat adapt their internal structure on the basis of subjective probabilities
constructed via computation of randomly received input signals. A principl
ed approach is provided that has the key property that it defines a probabi
lity density model that allows to study the convergence of the adaptation p
rocess. Certain neural network models (e. g. topological feature maps and a
ssociative networks) can be derived from our approach.