kerce@nu.cs.fsu.edu (Kingsley F. Kerce) (12/14/90)
In article <Dec.7.03.51.36.1990.17127@athos.rutgers.edu> autodesk!peb@uunet.uu.net (Paul Baclaski) writes: >In article <Dec.6.02.01.20.1990.22473@athos.rutgers.edu>, >dmocsny@minerva.che.uc.edu (Daniel Mocsny) writes: >> ...Suppose a theoretical limit exists to the maximum amount of >> intelligence that can exist in one coherent entity, before the >> subparts become so intelligent that they create their own >> independent agendas and rebel? > >Consider human organizations--the larger the organization, the >more bureaucracy occurs. Minksky proposes in his Society of >Mind (and in the epilogue of the new edition of Perceptrons >(which I highly recommend for some critical analysis of connectionism)) >that subparts would get gross overviews of what other subparts are >up to. The more subparts and the higher the bandwidth, the more >difficult this will be. Competition between subparts resulting in whole benefit is commonplace in nature. In fact, neural development is a very selective process in which neurons vie. This was first proposed in the late 1800s. In developing nervous systems, cells are overproduced and neuronal death plays a major role in the final neural pattern. For example, covering a newborn kitten's left eye, uncovering it after three months, and applying a light stimulus to that eye results in no activity in the visual cortex. All inputs to the visual cortex come from the right eye. The kitten is born with all the appropriate neuronal connections in its visual system, however, if one eye is covered all the connections are taken over by the other eye. The immune system is selective. Subparts of this protective system do not dynamically adjust their structure to fight invaders. Instead, the subparts which are indeed effective against intrusion--by virtue of their structure--will increase in quantity. In theory, selection occurs in groups of neurons (see G. Edelman's Theory of Neuronal Group Selection). At a higher level (see R. Brook's subsumption architecture for robot control) behaviors may compete for expression. In many circumstances, competition is healthy. -- Kingsley Kerce kerce@nu.cs.fsu.edu Dept of Computer Science B-173 FSU, Tallahassee, FL, 32306-4019 Work Phone: (904)644-8562
chiu@bchm1.aclcb.purdue.edu (Chiu) (12/19/90)
I am posting the following for my friend, Sandy Amass. Please direct any E-mail responses to amasss@dog.vet.purdue.edu __________________________________________________________________________ In article <Dec.13.16.31.53.1990.14113@athos.rutgers.edu>, kerce@nu.cs.fsu.edu (Kingsley F. Kerce) writes: > >In fact, neural development is a very selective process in which >neurons vie. This was first proposed in the late 1800s. In >developing nervous systems, cells are overproduced and neuronal death >plays a major role in the final neural pattern. For example, covering >a newborn kitten's left eye, uncovering it after three months, and >applying a light stimulus to that eye results in no activity in the >visual cortex. All inputs to the visual cortex come from the right >eye. The kitten is born with all the appropriate neuronal connections >in its visual system, however, if one eye is covered all the >connections are taken over by the other eye. I believe you are refering to the critical period of development in which neuronal connections are plastic to environmental stimuli. Your account is an oversimplification and thus, not entirely accurate. In the case of the kitten, abnormal connections relating to the eye do occur only if deprivation occurs during the first 3 or 4 postnatal months. After this critical period deprivation will not result in any abnormalities nor will any abnormalities suffered during this period be corrected. This is called neural plasticity. Most of the plasticity in single eye deprivation in experiments results from competition among developing axons for synaptic connections. However there are two visual segments, the monocular and the binocular segment. Despite deprivation, the monocular segment is not competitive and develops normally although slowly, but the binocular segment may have deficits. The fact that normal connections develop in the deprived monocular segment illustrate that the deficits in the binocular segment are NOT caused by deprivation, but rather they are the result of the effect of competitive interactions that become unbalanced during monocular deprivation. I just wanted to point out that the details are not as simple as you had stated and the statement that the nondeprived eye somehow takes over all the neuronal connections is false. The normal eye is no more powerful than it would have been had no deprivation occurred. What I have written is the simple version, although it may not seem to be. Actually individual cells are affected differently by the competition resulting from deprivation. In truth, this is a good demonstration of competition. For a more detailed account I recommend Berne and Levy's book _Physiology_, 2nd ed,1988, Ch 21. >The immune system is selective. Subparts of this protective system do >not dynamically adjust their structure to fight invaders. Instead, >the subparts which are indeed effective against intrusion--by virtue >of their structure--will increase in quantity. This is a drastic oversimplification and not correct. The selective part of the immune system is the humoral part which deals with antibody production. In general the immune system is not selective per se. The majority of the protective mechanisms, ie. mucous production, pH, and the most important element of all, the skin, are there to keep any foriegn invaders out. They are not specific as to which invaders they do keep out. The second sentence is entirely false. Certain cells do indeed "adjust their structure to fight invaders." I choose the macrophage as the prime example. The function of the macrophage is to phagocytose ( eat) invaders. When an infection occurs, these cells become activated. They increase in size, mobility, and metabolic activity. Phagocytosis is enhanced as is their ability to kill tumors and microbes. They even change markedly in physical appearance. I remind you that this is merely one example, but many are to be found. I agree that certain subparts of the immune system, mainly antibody production, do increase, however to imply that antibodies are the entire immune system, or even the most important part is a narrow and incomplete view of the immune system. Regardless of how you look at it, this is not an example of competition. I refer you to Tizard's _Veterinary Immunology_. 1987 for more information. >In many circumstances, competition is healthy. I agree that competition is healthy, however, I disagree with the validity of the details of the first example and the entirety of the second example which you have chosen. I cannot offhand think of any other examples aside from neuronal plasticity in which like cells of the body compete. But unlike cells do "compete" for nutrients such as oxygen and glucose,etc. For example, during exercise, more blood goes to the skeletal muscle than to the gut. Hence more oxygen is available to the tissue which has the most demand at the time. I am not sure that this is competition as it is neuronally regulated. In general, cells within the same organism tend to act in concert. A good example of competition within the body is the prevention of colonization of pathogenic bacteria. In most cases when a foreign bacterium is ingested its colonization of the gut is prevented by competition with normal flora for nutrients and space. >-- >Kingsley Kerce kerce@nu.cs.fsu.edu >Dept of Computer Science B-173 >FSU, Tallahassee, FL, 32306-4019 >Work Phone: (904)644-8562 Name: Chiu Internet: chiu@aclcb.purdue.edu Phone: ["Competition" can be a loaded term and it is best to be careful both when using it and criticizing its use. A good source for speculations concerning the importance of Darwinian mechanisms in the nature of thought and the mind (not necessarily physically in the brain) is W. Calvin's book "The Cerebral Symphony" reviewed here some months ago. --JoSH]
mikep@hpmwtd.hp.com (Mike Powell) (12/21/90)
Great idea about being able to speed up or slow down the brain in order to keep from going crazy... But the mention of sliding on the ice, and kicking into high speed made me think of a nasty possibility here.... Imagine being in slow gear, walking across the street. You look over your shoulder to see a large truck is about to hit you. You shift your brain into high gear... What would have been a second or two of terror followed by the bliss of being knocked out cold (or possibly death) has now been replaced by minutes or hours of extreme horror.... the only possible salvation being to shift back into low gear to get it over with, thereby avoiding the intense mental stress... but who could allow themselves to 'downshift' in such a situation, bringing the inevitable injury 'sooner'. It could amount to long periods of panic for people who are thinking at such high speeds... Wouldn't this be potentially more damaging then being hit by a truck? -Mike P- [I'll bet you the truck problem gets solved first (i.e. supermedicine) before the hi/low brain gets invented. It's hard to inagine an everyday type accident that total molecular analysis and reconstruction couldn't cure you from. --JoSH]