Hi Ian, Thank you for posting these access-routes.
I've read the paper, and stand on what I've posted, elsewhere in the
thread.
I'm =Sorry=.
The experimental design is too artificial [it's flat-out 'engineered'
to produce the sought-after result].
- sliced [cut-off from in vivo i/o]
- perfused to control functionality
- injection of tetanic stimulation [for up to 80 minutes]
If the Authors give their permission, I'll go over the paper
line-by-line.
[I'll be interested to see how IBM's stock performed yesterday,
though :-]
k. p. collins
Ian Goddard wrote in message <3d507852.100035467 at news.erols.com>...
>On 5 Aug 2002 23:30:44 +0100, rcb5 at msn.com ("Ron Blue") wrote:
>>>> Kenneth Collins wrote in message ...
>>> >mat wrote in message
>>> ><43525ce3.0208050245.702a29ca at posting.google.com>...
>>> >>[...]
>>> >>You claim the natural tendency of neural tissue is to
>>> >>minimize excitation, whereas in fact quite the opposite is true
>>> >>(see the work of Traub et al.).
>>> >
>>> >Got a specific ref[?] ("anyone, anyone anyone[?"] :-)
>>>>Traub et al (1996) reported that the brain would coherently
oscillate within
>>two milliseconds after a doublet spike that allows synchronous
neuronal
>>oscillations in the 30-70 hertz range. The coherent synchronous
oscillation
>>will occur over large distance. Oscillations slower that 30-hertz
will cause
>>the system to become discoherent.
>>>>Traub, R.D.; Whittington, M.A.; Stanford, I.M.; & Jefferys, J.G.R.
>>(1996) A mechanism for generation of long-range synchronous fast
>>oscillations in the cortex. Nature 382, 621-624
>>>Nature 1996 Oct 17;383(6601):621-4
>>A mechanism for generation of long-range synchronous fast
oscillations
>in the cortex.
>>Traub RD, Whittington MA, Stanford IM, Jefferys JG.
>>IBM Research Division, T. J. Watson Research Center, Yorktown
Heights,
>New York 10598, USA.
>>Synchronous neuronal oscillations in the 30-70 Hz range, known as
>gamma oscillations, occur in the cortex of many species. This
>synchronization can occur over large distances, and in some cases
over
>multiple cortical areas and in both hemispheres; it has been
proposed
>to underlie the binding of several features into a single perceptual
>entity. The mechanism by which coherent oscillations are generated
>remains unclear, because they often show zero or near-zero phase
lags
>over long distances, whereas much greater phase lags would be
expected
>from the slow speed of axonal conduction. We have previously shown
>that interneuron networks alone can generate gamma oscillations;
here
>we propose a simple model to explain how an interconnected chain of
>such networks can generate coherent oscillations. The model
>incorporates known properties of excitatory pyramidal cells and
>inhibitory interneurons; it predicts that when excitation of
>interneurons reaches a level sufficient to induce pairs of spikes in
>rapid succession (spike doublets), the network will generate gamma
>oscillations that are synchronized on a millisecond time-scale from
>one end of the chain to the other. We show that in rat hippocampal
>slices interneurons do indeed fire spike doublets under conditions
in
>which gamma oscillations are synchronized over several millimetres,
>whereas they fire single spikes under other conditions. Thus, known
>properties of neurons and local synaptic circuits can account for
>tightly synchronized oscillations in large neuronal ensembles.
>>PMID: 8857537 [PubMed - indexed for MEDLINE]
>>http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8857537&dopt=Abstract
>>********************************************************************
*
>FULL PAPER FOR FREE:
http://www.pnas.org/cgi/content/full/94/22/12198
>********************************************************************
*
>>Proc Natl Acad Sci U S A 1997 Oct 28;94(22):12198-203
>>Recurrent excitatory postsynaptic potentials induced by synchronized
>fast cortical oscillations.
>>Whittington MA, Traub RD, Faulkner HJ, Stanford IM, Jefferys JG.
>>Department of Physiology and Biophysics, Imperial College School
>of Medicine at St. Mary's, London W2 1PG, United Kingdom.
>m.whittington at sm.ic.ac.uk>>Gamma frequency (about 20-70 Hz) oscillations occur during novel
>sensory stimulation, with tight synchrony over distances of at least
7
>mm. Synchronization in the visual system has been proposed to
reflect
>coactivation of different parts of the visual field by a single
>spatially extended object. We have shown that intracortical
>mechanisms, including spike doublet firing by interneurons, can
>account for tight long-range synchrony. Here we show that
synchronous
>gamma oscillations in two sites also can cause long-lasting (>1 hr)
>potentiation of recurrent excitatory synapses. Synchronous
>oscillations lasting >400 ms in hippocampal area CA1 are associated
>with an increase in both excitatory postsynaptic potential (EPSP)
>amplitude and action potential afterhyperpolarization size. The
>resulting EPSPs stabilize and synchronize a prolonged beta frequency
>(about 10-25 Hz) oscillation. The changes in EPSP size are not
>expressed during non-oscillatory behavior but reappear during
>subsequent gamma-oscillatory events. We propose that
>oscillation-induced EPSPs serve as a substrate for memory, whose
>expression either enhances or blocks synchronization of spatially
>separated sites. This phenomenon thus provides a dynamical mechanism
>for storage and retrieval of stimulus-specific neuronal assemblies.
>>PMID: 9342386 [PubMed - indexed for MEDLINE]
>>http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9342386&dopt=Abstract
>>>http://IanGoddard.net>> Something can come from nothing if, and only if,
> that something is equal to nothing ((+)+(-)) = 0.
>>
