Vistas from tensor network theory: a horizon from reductionalistic neurophilosophy to the geometry of multi-unit recordings

The brain and the computer: a misleading metaphor in place of brain theoryContrary to the philosophy of natural sciences, the brain has always been understood in terms of the most complex scientific technology of manmade organisms, for the simple reason of human vanity. Before and after the computer era, the brain was paraded in the clothing of hydraulic systems (in Descartes' times), and in the modern era as radio command centers, telephone switchboards, learn-matrices or feedback control amplifiers. Presently, it is fashionable to borrow terms of holograms, catastrophes or even spin glasses. Comparing brains to computers, however, has been by far the most important and most grossly misleading metaphor of all. Its importance has been twofold. First, the early post-war era was the first and last time in history that such analogy paved the way both to a model of the single neuron, the flip–flop binary element, cf. McCulloch & Pitts, 1943, and to a grand mathematical theory of the function of the entire brain (i.e., information processing and control by networks implementing Boolean algebra, cf. Shannon, 1948; Wiener, 1948). Second, the classical computer, the so-called von Neumann machine, provided neuroscience with not only a metaphor, but at the same time with a powerful working tool. This made computer simulation and modeling flourish in the brain sciences as well (cf. Pellionisz, 1979).The basic misunderstanding inherent in the metaphor, nevertheless, left brain theory in an eclipse, although the creator of the computers was the first to point out (von Neumann, 1958) that these living- and non-living epitomes of complex organisms appear to operate on diametrically opposite structuro–functional principles.