So-- what happens with a few extra stem cells in your brain?
it is being worked on
intriguing
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Naturwissenschaften 2001 Jan;88(1):2-12
The immunoglobulin-like genetic predetermination of the brain: the
protocadherins, blueprint of the neuronal network.
Hilschmann N, Barnikol HU, Barnikol-Watanabe S, Gotz H, Kratzin H, Thinnes FP.
Max-Planck-Institut fur experimentelle Medizin, Gottingen, Hermann-Rein-Strasse
3, 37075 Gottingen, Germany. [log in to unmask]
The morphogenesis of the brain is governed by synaptogenesis.
Synaptogenesis in
turn is determined by cell adhesion molecules, which bridge the synaptic cleft
and, by homophilic contact, decide which neurons are connected and which are
not. Because of their enormous diversification in specificities, protocadherins
(pcdh alpha, pcdh beta, pcdh gamma), a new class of cadherins, play a decisive
role. Surprisingly, the genetic control of the protocadherins is very
similar to
that of the immunoglobulins. There are three sets of variable (V) genes followed
by a corresponding constant (C) gene. Applying the rules of the immunoglobulin
genes to the protocadherin genes leads, despite of this similarity, to quite
different results in the central nervous system. The lymphocyte expresses one
single receptor molecule specifically directed against an outside stimulus. In
contrast, there are three specific recognition sites in each neuron, each
expressing a different protocadherin. In this way, 4,950 different neurons
arising from one stem cell form a neuronal network, in which homophilic contacts
can be formed in 52 layers, permitting an enormous number of different
connections and restraints between neurons. This network is one module of the
central computer of the brain. Since the V-genes are generated during evolution
and V-gene translocation during embryogenesis, outside stimuli have no influence
on this network. The network is an inborn property of the protocadherin genes.
Every circuit produced, as well as learning and memory, has to be based on this
genetically predetermined network. This network is so universal that it can cope
with everything, even the unexpected. In this respect the neuronal network
resembles the recognition sites of the immunoglobulins.
PMID: 11261353[PubMed - indexed for MEDLINE]
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Ray Strand
Prairie Sky Design
-----------------( on the Edge of the Prairie Abyss )---------------
when the sky is clear
the ground is visible
49/dx PD 2 yrs/40? onset/retired
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