Convergence-divergence zone
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The theory of convergence-divergence zones [1][2] was proposed by Antonio Damasio, in 1989, to explain the neural mechanisms of recollection. It also helps to explain other forms of consciousness: creative imagination, thought, the formation of beliefs and motivations ...
It is based on two key assumptions: 1) Imagination is a simulation of perception. 2) Brain registrations of memories are self-excitatory neural networks (neurons can activate each other).
A convergence-divergence zone (CDZ) is a neural network which receives convergent projections from the sites whose activity is to be recorded, and which returns divergent projections to the same sites. When an experiment is recorded, the signals that converge on the CDZ excite their neurons which strengthen their mutual connections (according to the Hebbian theory) and thus form a self-excitatory network. The excitation of this network is then enough to reproduce the combination of initially received signals. In a self-excitatory network the excitation of a part spreads to all the others, just like a memory fragment awakens an entire recorded experience. A CDZ is thus the place of recording and reproduction of memories. It is both a detector and a signal producer (forms of neuronal activation). This is the basic neural mechanism that explains memories and other forms of imagination.[citation needed]