Piero Scaruffi(Copyright © 2013 Piero Scaruffi | Legal restrictions )
These are excerpts and elaborations from my book "The Nature of Consciousness"
Binding Brain and Consciousness
Knowledge about the world is distributed around the brain. How it is then integrated into one unitary perception is the "binding" problem.
This problem occurs at several levels. A sensory input is channeled through several different areas of the brain, each brain region focusing on one aspect of the input, but then somehow the mind perceives the whole input as something that happens at the same time in the same place, and it is a whole. The "binding" problem refers to how the brain creates the whole perception out of a sensory input that has been fragmented around the brain.
For example, a visual input is "split" so that one brain region analyzes the shape and one brain region analyzes the color. But somehow these separate pieces of information are joined again to produce the overall sensation of the image. At a higher level, different sensory inputs come together: the sound of an event is merged with the image of the event, or the smell of the event, or the touch of the event. The result is the overall feeling of the situation.
At an even higher level, the situation is merged with pre-existing memories and concepts. We don't only see a human being moving and speaking around us: we see our friend X talking to us. At the highest level, this entire complex system of feelings and knowledge "feels" unified in our consciousness. There is "one" feeling of "me" existing in a "world". Somehow all has been "bound" together into consciousness.
There are different theories about where and how and when this ultimate form of "binding" could occur.
“Space-based binding” is advocated by scientists who believe that there is a specific place in the brain where all information is integrated together. In the 1990s, a competing paradigm has emerged which is based on time instead of space, and is therefore referred to as "time-based binding": there is no particular place where the integration occurs, because integration occurs over the entire brain, and is regulated by some periodic process.
Space-based binding theories try to identify the "homunculus" in the brain that is responsible for running the integration process.
The working memory is a popular candidate for such a task, but no piece of the brain seems likely to show us the transformation of electrochemical processes into “feelings” (conscious processes).
According to the Portuguese neurobiologist Antonio Damasio, the story is more complex. There is not just one working memory: there is a whole system of "convergence zones". The brain has "convergence zones" and convergence zones are organized in a hierarchy: lower convergence zones pass information to higher convergence zones. Lower zones select relevant details from sensory information and send summaries to higher zones, which successively refine and integrate the information. In order to be conscious of something, a higher convergence zone must retrieve from the lower convergence zones all the sensory fragments that are related to that something. Consciousness of something occurs when the higher convergence zones fire signals back to lower convergence zones.
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