Plato's theory of ideas revisited

According to Plate's theory, every pattern perceived by the mind is a composition of raw concepts (ideals). In this paper it is argued that the thalamus can decompose input patterns into these ideals and, during development, generate them from incoming patterns. As the neuronal counterpart of a certain ideal is proposed to be the activation of a reticular neuron inside a competitive layer in the thalamus, these ideals are not coincident over time. In order to recruit the ideals of a certain pattern, ideals are delayed in the long dendrites of pyramidal neurons. When several parts of a pattern are to be related, these are bound through the association of their equal constituent ideals. Coincidences of the same ideals are stored through synaptic reinforcement in nearby spines of pyramidal neurons. After binding, if a partial pattern is input, it will be reconstructed by the recall of its ideals over the reinforced synapses. (C) 1997 Elsevier Science Ltd.