Dissociation in brain and mind as a consequence of competitive interactions.

We show some connections between psychodynamic view of the psychic system, in which dissociation is a basic element of the system dynamics, and neural level of the brain. The dissociation represents competition among complexes that correspond to ideas or mental representations in parallel distributed processing (PDP). In PDP models dissociation represents low synaptic strength among mental representations and neural assemblies as their neural correlate. When this associated strength in activated ranges of the neural network is low, it leads to strong competition among the cell assemblies, which represent these mental representations. As a consequence of a strong competition among mental representations deterministic chaos is present. It leads to often instantaneous reduction of excitatory thresholds of many neural populations not excited in that particular combination before. Its EEG correlate is hypersynchronized activity--a burst. We show some examples in which experimental manifestations of psychic competition (dissociation) are correlated by burst EEG activity. It corresponds to theoretical connections and supports this hypothesis that dissociation in the psychodynamic sense may be grasped as competitive relationship of mental representations and their neural correlates (neural assemblies).