From: Martin Striz (mstriz@gmail.com)
Date: Wed Apr 12 2006 - 14:20:47 MDT
On 4/12/06, Phillip Huggan <cdnprodigy@yahoo.com> wrote:
>
>
> On 4/12/06, Phillip Huggan wrote:
> > Actually it is both. Neurons have both the standard electrochemical
> > propagation pathway and electrical currents too.
> Well, yeah, that's HOW you get a voltage change. But electrochemical
> flow is only locally across a membrane, not down the axon.
> Martin
>
> No. There are actually electrical synapses in addition to electrochemical
> synapses. Other non neuron=logic gate effects I can identify merely by
> pawning from the neuron wiki include the fact that axons also transmit to
> other axons.
You must be talking about gap junctions. Those started out as
cellular passage ways for transmitting biomolecules (so that
neighboring cells with similar functions can maintain similar internal
environments) but can be used to transmit Ca++ and H+, which is
electrochemical, not electricity per se (Ca is also diffused
extracellularly in the brain to get certain neuronal populations into
synchrony). Crucially, they are used for local signal transmission,
not for propagation of the signal over long distances. Electrical
synapses, like any other synapse, are local phenomena.
As I said before, the real benefit of the nervous system is speed,
particularly over long distances. Nervous systems can encode
information about the environment and respond adaptively in real time.
They operate over milliseconds to seconds, whereas purely chemical
signalling takes minutes to hours. That could be done with a purely
electrical system, but it wasn't.
> There are a handful of different neuron families and over 10000 different
> types of cells at play in constructing our brains. People here are talking
> about building consciousness and we haven't even delved into the *easy*
> chemical behaviour of certain brain centers. I suggest Google before making
> such grandoise claims as neurons = logic gates = human consciousness. For
> instance, the neuron wiki refutes that.
I don't remember making that claim.
Martin
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