[ExI] StemCells Inc.and Alzheimer's.

[Jeff Davis]

Anders writes:

> Remember that 75% of the input to the lateral geniculate nucleus comes from
> the cortex, not the eye.

Anders,

A question or two.

Synaptic firing periodicity.

A neuron to neuron synapse fires.  Axonal terminus to dendritic input.
 How frequently can it do this?    [What is the neuronal firing
frequency?  Is it variable in a given neuron, or in different neuron
types, or by location/function?  I'm talking about brain only --
include the brain stem if you want -- not the sympathetic nervous
system, spinal cord, or motor neurons.]

The signal arrives at its dendritic destinations, where, presumably,
the process is repeated.

Expand this isolated microscopic event by billions of neurons and
trillions of synapses, to the whole brain in glorious action.  This
"action" is more or less continuous from pre-natal to mortal
close-of-business, is it not?

>From Wikipedia: Neural oscillations

"At the level of neural ensembles, synchronized activity of large
numbers of neurons can give rise to macroscopic oscillations,... .
Oscillatory activity in groups of neurons generally arise from
feedback connections between the neurons that result in the
synchronization of their firing patterns."

I'm trying to get a picture of the spacial distribution of the firing
pattern: the feedback loops, the "synchronization" of these firings,
and from-where-to-where-and-back-again layout.

For instance, you wrote:

"...75% of the input to the lateral geniculate nucleus comes from the cortex..."

The cortex is the outer layer (or is that the neocortex?).  Where is
the geniculate nucleus?  And after receiving the input does it
repeatedly fire back to the cortex in a feedback loop?  Or,
alternatively, does it fire to other intermediate locations and only
then back to the cortex?  Is there ongoing oscillation here, and
synchronization?

I've broken my rule here, not to ask a question before doing my
homework, so I'll take a link to the answer, in lieu of a long reply.

Thanks.

Best, Jeff Davis

        "You are what you think."
                       Jeff Davis