Brain MindComputer 21 Metaphors of Consciousness

Systems for information processing are evolving within both biological life forms and computer technologies. The most highly evolved information processing system currently appears to be human consciousness which resides in the human brain. The scientific relationships between consciousness and structural brain activities remain obscure and are often referred to as the brain/mind "duality." To explain this duality, humans have historically perceived their minds in the context of predominant cultural themes, particularly information technologies. Author Julian Jaynes (1976) has chronicled how the metaphors of the mind are the world it perceives. The trail of brain/mind metaphors perhaps began during the Greeks' Golden Age. According to Plato, Socrates said:

Imagine ... that our minds contain a block of wax ... and say that whenever we wish to remember something we hear or conceive in our own minds, we hold this wax under the perceptions or ideas and imprint them on it as we might stamp the impression of a seal ring.

The Greeks traveled about in freedom (while their slaves did the work) and consciousness was perceived by free men as a free entity. Heraclitus described consciousness as an "enormous space whose boundaries could never be found out." Later, Augustine of Carthage described "the mountains and hills of my high imagination," "the plains and caves and caverns of my memory" with "spacious chambers wonderfully furnished with innumerable stores."

The geological discoveries in the 19th century revealed a record of the past written in layers of the earth's crust. Consciousness became viewed as layers recording an individual's past in deeper and deeper layers until the original record could no longer be read. This emphasis on the unconscious mind grew until the late 19th century when most psychologists thought that' consciousness was but a small part of the mind. As chemistry superceded geology in scientific esteem, consciousness became viewed as a compound structure that could be analyzed in a laboratory into precise elements of sensations and feelings. When steam engines became commonplace, the subconscious was perceived as a boiler of straining energy demanding release, and when repressed, pushing up and out into neurotic behavior. In the early part of the 20th century, mind metaphors continued to encompass technologies for information processing such as telephone switching circuits, tape recorders, clocks, holograms, and computers.

The computer is the most recent brain/mind metaphor and has evolved qualitatively beyond its predecessors (as has human consciousness). Computer technology has approached, and in some cases surpassed, some aspects of human brain function such as "brute force" calculations. Computers may also be used to simulate dynamical systems (including the brain), thus providing a metaphorical medium. In efforts to construct computing machines capable of independent logic and decision making, artificial intelligence (AI) researchers have examined what is known about the workings of the brain and mind. Accordingly, they have been led away from classical "serial" computers towards massively parallel systems with high degrees of lateral interconnection. Because the brain at first glance is a parallel aggregation of billions of neurons with tens of thousands of connections per neuron, AI researchers of the connectionist school have viewed and modeled the brain as "neural networks" which may be simulated on conventional computers. These neural net models, to be discussed later in this book, are based on relatively simple assumptions regarding interneuronal synapses as switches between neurons. Dynamic patterns of neural net activity can simulate systems capable of learning, independent recognition, different "mental" states, and with some imagination, rudimentary consciousness. The general architecture of parallel computers is similar to neurons within the brain, and can take advantage of simultaneous processing with lateral resolution of conflicting concepts. Despite these apparent similarities, the brain's complexity and the dynamic vastness of human consciousness remain unassailable by current technology. The mind remains enigmatic to brain and computer.

Figure 2.1: The Brain/Mind/Computer metaphorical triangle. Is the cytoskeleton the key to understanding?

Brain, mind, and computer are mutually metaphorical; each is related to the other in ways that are not clearly understood. This impasse, the "brain/mind/computer triangle," is based on an incorrect assumption. The irreducible substrate of information processing within the brain has been assumed to be the notoriously slow interneuronal synapse. Consequently, synapses have been compared to simple switches, and the brain has been compared to a computer composed of a collection of synaptic switches. Because each neuron within the brain has up to several hundred thousand synapses, it must "integrate" information from among these synapses to regulate its output. Neurons utilize a variety of analog functions including dendritic morphology, slow wave membrane properties, and cytoskeletal activities which determine their responses within neural networks, and which alter synaptic efficacy as apparent mechanisms of learning. Thus each of the billions of neurons in the brain is a computer. Similarly, single cell organisms which have no synapses and are independent agents perform complex tasks involving rudimentary decision making, behavior, and organization. Thus, the basic irreducible substrate of information should reside within biological cells, and the brain may then be viewed as an organized assembly of billions of computers in which collective emergent properties may be specifically related to consciousness. The hierarchy of brain organization may thus have a secret basement-a new "dimension." Advances in intracellular imaging and molecular biology have illustrated the complex dynamic organization of intracellular cytoplasm. Specifically a dense, parallel, highly interconnected solid state network of dynamic protein polymers, the "cytoskeleton," is a medium which appears to be ideally suited for information processing, and which is actively involved in virtually all cell functions. Appreciation of this "cytoskeletal dimension" may be the key to the brain/mind/computer triangle (Figure 2.1).

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