Piero Scaruffi(Copyright © 2013 Piero Scaruffi | Legal restrictions )
These are excerpts and elaborations from my book "The Nature of Consciousness"
A new paradigm was introduced in the 1980s by the Portuguese biologist Antonio Damasio.
When an image enters the brain via the visual cortex, it is channeled through "convergence zones" in the brain until it is identified. Each convergence zone handles a category of objects (faces, animals, trees, etc.) A convergence zone does not store permanent memories of words and concepts but helps reconstructing them. A convergence zone is not a "store" of information, but an “agent” capable of decoding a signal (of reconstructing information). In this function, they resemble an “index” that can be used to organize a perception.
There is no specialized region of the brain that encodes an event (a memory). The various features of a perception are held in the places where they were analyzed (somewhere in the cortex). The convergence zones are different regions of brain that manage the task of connecting those fragments of perceptions and of connecting them to previous "memories". Convergent zones also produce output. If convergence zones reactivate simultaneously fragments that used to be connected when they were first "memorized", then we "remember" the event represented by the set of those fragments.
Once an image has been identified, an acoustic pattern corresponding to the image is constructed by another area of the brain. Finally an “articulatory” pattern is constructed so that the word that the image represents can be spoken. There are about twenty known categories that the brain uses to organize knowledge: fruits/vegetables, plants, animals, body parts, colors, numbers, letters, nouns, verbs, proper names, faces, facial expressions, emotions, sounds.
Convergence zones exist at several levels. A convergence zone may be responsible for linking the attributes of a face, while another may be responsible for linking the face to other concepts or faces.
Convergence zones form a hierarchy of specialized agents (although they are connected in a network-like fashion). Each convergence zone is the focal point for the integration of disparate features. Convergence zones “bind” together objects, concepts and events at different levels of cognition.
Convergence zones behave like indexes that draw information from other areas of the brain. The memory of something is stored in bits at the back of the brain (near the gateways of the senses): features are recognized and combined and an index of these features is formed and stored. When the brain needs to bring back the memory of something, it will follow the instructions in that index, recover all the features and link them to other associated categories. As information is processed, moving from station to station through the brain, each station creates new connections reaching back to the earlier levels of processing. Convergence zones enable the brain to work in reverse.
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