Editing Gerald Edelman (section)

===Neural Darwinism===
Edelman's theory of neuronal group selection, also known as '[[Neural Darwinism]]', has three basic tenets—Developmental Selection, Experiential Selection and Reentry.
# '''Developmental selection''' -- the formation of the gross anatomy of the brain is controlled by genetic factors, but in any individual the connectivity between neurons at the synaptic level and their organisation into functional neuronal groups is determined by somatic selection during growth and development. This process generates tremendous variability in the neural circuitry—like the [[fingerprint]] or the [[Iris (anatomy)|iris]], no two people will have precisely the same synaptic structures in any comparable area of brain tissue. Their high degree of functional plasticity and the extraordinary density of their interconnections enables neuronal groups to self-organise into many complex and adaptable "modules."  These are made up of many different types of neurons which are typically more closely and densely connected to each other than they are to neurons in other groups.
# '''Experiential selection''' -- Overlapping the initial growth and development of the brain, and extending throughout an individual's life, a continuous process of synaptic selection occurs within the diverse repertoires of neuronal groups. This process may strengthen or weaken the connections between groups of neurons and it is constrained by value signals that arise from the activity of the ascending systems of the brain, which are continually modified by successful output. Experiential selection generates dynamic systems that can 'map' complex spatio-temporal events from the sensory organs, body systems and other neuronal groups in the brain onto other selected neuronal groups. Edelman argues that this dynamic selective process is directly analogous to the processes of selection that act on populations of individuals in species, and he also points out that this functional plasticity is imperative, since not even the vast coding capability of entire human genome is sufficient to explicitly specify the astronomically complex synaptic structures of the developing brain.<ref>Gerald Edelman, ''Bright Air, Brilliant Fire'' (Penguin, 1992), p.224</ref>
# '''Reentry''' {{Main|Reentry (neural circuitry)}}—the concept of reentrant signalling between neuronal groups. He defines reentry as the ongoing recursive dynamic interchange of signals that occurs in parallel between brain maps, and which continuously interrelates these maps to each other in time and space ([http://www.acamedia.info/movs/edelman/reentrant_signaling.flv film clip]: Edelman demonstrates spontaneous group formation among neurons with re-entrant connections).<ref>Gerald Edelman: "[http://video.google.com/videoplay?docid=7437432153763631391 From Brain Dynamics to Consciousness: A Prelude to the Future of Brain-Based Devices] {{Webarchive|url=https://web.archive.org/web/20120106110348/http://video.google.com/videoplay?docid=7437432153763631391|date=January 6, 2012}}", Video, IBM Lecture on Cognitive Computing, June 2006</ref> Reentry depends for its operations on the intricate networks of massively parallel reciprocal connections within and between neuronal groups, which arise through the processes of developmental and experiential selection outlined above. Edelman describes reentry as "a form of ongoing higher-order selection ... that appears to be unique to animal brains" and that "there is no other object in the known universe so completely distinguished by reentrant circuitry as the human brain."