The Survival of the Wittiest
Count_Artblay at hotmail.com
Tue Jan 15 19:54:34 EST 2002
Anno Domini <2001>, verba <Count_Artblay at hotmail.com> hic et nunc in publicae
tabellae collectae , in foro <bionet.neuroscience>(et alii) atque :
Would anybody be so kind to mail or post here some authors
that wrote about "Science" on itself (like Karl Popper) :
I'm aiming 'what about' :
- Neurobiology - Chemistry
- the infinte - infinitecimal problem
- Modern Science after the Nuclear Discoveries
Thanks a lot,
>minsky at media.mit.edu (Marvin Minsky) wrote:
The real one ?
The one that said :" As often teachers only understand what they teach after
explaining it for the first time" ?
>> marko_amnell at hotmail.com (Marko Amnell) wrote:
>> > HOW BRAINS THINK: THE EVOLUTION OF INTELLIGENCE
>> > by William Calvin is a good exposition of the
>> > "neural Darwinism" thesis by the man who coined
>> > the term "Darwin machines". Occasional RAB contributor
>> > Marvin "The Society of Mind" Minsky gets a mention in
>> > a footnote for his 1994 Scientific American article
>> > "Will robots inherit the earth?".
>> I've put that on my home page at
>> Actually it's more about the prospects for human immortality.
>Thanks. _Consciousness: How Matter Becomes Imagination_ by
>Gerald Edelman and Giulio Tonori is another good book on
>Neural Darwinism. It's more comprehensive than William Calvin's
>_How Brains Think_ (and even contains a few mathematical
>equations). I believe Edelman actually was the first to propose
>the Neural Darwinism hypothesis in the late 1970s. What is it?
>Well, just listing a few principles doesn't explain much, but
>this is how Edelman and Tononi introduce Neural Darwinism
>"In considering the origin of species, Charles Darwin made a
>great contribution that centered on population thinking: the
>idea that variation or diversity among individuals in a population
>provides a basis for competition during natural selection. Natural
>selection is reflected in the differential reproduction of fitter
>individuals in a species. In principle, selective events require
>the continual generation of diversity in repertoires of individual
>variants, the polling by environmental signals of these diverse
>repertoires, and the differential amplification or reproduction
>of those repertoire elements or individuals that match such
>signals better than their competition. Could it be that the
>brain follows such principles? We believe it does, and in this
>chapter we briefly review some aspects of neuronal group selection,
>or Neural Darwinism. This theory embraces these selective principles
>and applies them to the functioning brain. Its main tenets are
>(1) the formation during brain development of a primary repertoire
>of highly variant neuronal groups that contribute to neuroanatomy
>(2) the formation during experience of a secondary repertoire of
>facilitated neural circuits as a result of changes in the strength
>of connections or synapses (experiental selection), and
>(3) a process of reentrant signaling along reciprocal connections
>between and among distributed neuronal groups to assure the
>spatiotemporal correlation of selected neural events.
>Together, the three tenets of this global brain theory provide a
>powerful means for understanding the key neural interactions that
>contribute to consciousness. ...
>This theory of neuronal group selection (TNGS), or Neural Darwinism,
>has three main tenets ...
>1. Developmental selection. During the early development of
>individuals in a species, formation of the initial anatomy of
>the brain is certainly constrained by genes and inheritance.
>But from early embryonic stages onward, the connectivity at the
>level of synapses is established, to a large extent, by somatic
>selection during each individual's ongoing development. For
>example, during development, neurons extend myriads of branching
>processes in many directions. This branching generates extensive
>variability in the connection patterns of that individual and
>creates an immense and diverse repertoires of neural circuits.
>Then, neurons strengthen and weake their connections according
>to their individual patterns of electrical activity: Neurons
>that fire together, wire together. As a result, neurons in a
>group are more closely connected to each other than to neurons
>in other groups.
>2. Experiental selection. Overlapping this early period and
>extending throughout life, a process of synaptic selection
>occurs within the repertoire of neuronal groups as a result
>of behavioral experience. It is known, for example, that
>maps of the brain corresponding to tactile inputs from the
>fingers can change their boundaries, depending on how much
>different fingers are used. These changes occur because
>certain synapses within and between groups of locally
>coupled neurons are strengthened and others are weakened
>without changes in the anatomy. This selectional process
>is constrained by brain signals that arise as a result of the
>activity of diffusely projecting value systems, a constraint
>that is continually modified by successful output.
>3. Reentry. The correlation of selective events across the
>various maps of the brain occurs as a result of the dynamic
>process of reentry. Reentry allows an animal with a variable
>and uniquely individual nervous system to partition an
>unlabeled world into objects and events in the absence of a
>homunculus or computer program. As we have already discussed,
>reentry leads to the synchronization of the activity of
>temporally coherent output. Reentry is thus the central
>mechanism by which the spatiotemporal coordination of
>diverse sensory and motor events takes place.
>The first two tenets, developmental and experiental selection,
>provide the bases for the great variability and differentiation
>of distributed neural states that accompany consciousness. The
>third tenet, reentry, allows for the integration of those states. ...
>It is important to emphasize that reentry is not feedback. Feedback
>occurs along a *single* fixed loop made of reciprocal connections
>using previous *instructionally* derived information for control
>and correction, such as an error signal. In contrast, reentry
>occurs in selectional systems across *multiple* parallel paths
>where information is not prespecified. Life feedback, however,
>reentry can be local (within a map) or global (among maps and
>Reentry carries out several major functions. For example, it can
>account for our ability to discern a shape in a display of moving
>dots, based on interactions between brain areas for visual movement
>and shape. Thus, reentry can lead to the construction of new
>response properties. It can also mediate the synthesis of brain
>functions by connecting one submodality, such as color, to another,
>such as motion. It can also resolve conflicts among competing
>neural signals. Reentry also ensures that changes in the efficacy
>of synapses in one area are affected by the activation patterns
>of distant areas, thereby making local synaptic changes context-
>dependent. Finally, by assuring the spatiotemporal correlation
>of neuronal firing, reentry is the main mechanism of neural integration.
>Since the formulation of the TNGS, considerable evidence to support
>the theory has accumulated."
>Unfortunately, Edelman and Tononi are not very explicit about
>the nature of this evidence. Does anyone know what is the best
>current evidence in support of the hypothesis of Neural Darwinism?
>Or is there some crucial evidence against the theory? Can anyone
>recommend other good books on Neural Darwinism, for or against?
>Are there good articles or papers on the subject that are
>available on the world wide web? Thanks in advance.
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