neurotransmitter storage (all or one?)

zu_enlil at my-deja.com invalid at hgmp.mrc.ac.uk
Wed Aug 30 00:00:14 EST 2000


On Fri, 25 Aug 2000 00:09:32 -0600, "Phoenix" <phoenix42 at uswest.net>
wrote:

><SNIP>
>> Until relatively recently it was thought that a neuron only released
>> one type of neurotransmitter. This is now known to be untrue. But no
>> neuron, AFAIK, produces all the neurotransmitters (there are more than
>> 100). Most are restricted to only a small few at best. Indeed, most of
>> the 100 billion or so neurons are primarily either glutamatergic or
>> GABAergic, the most common (mainly) excitatory and (mainly) inhibitory
>> NTs respectively.
><SNIP>
>
>Hmmmm, interesting.
>
>It sounds as though the brain is sorta like a computer that is not based on
>binary. Neurons receiving multiple types of stimuli and responding with a
>neurotransmitter within it's range of capabilities. Since different neurons
>have different ranges of responses, I wonder if different regions of the
>brain work with different base systems?

You need to realise that brain/mind function is more than just
neurotransmitter release and "action potentials."  Nor are neurons
necessarily just influenced by other neurons. The activity of glial
cells can also have an effect by changing ion concentration in the
extracellular fluid, for example. Even the differences produced by
variation in the metabolic function of the body during night v day
can alter the way neurons "react."

>Are neurons with more limited, and perhaps similar, capabilities grouped
>together? If so, are neurons with greater capabilities grouped together as
>well, or do they form a boarder between more limited groups (perhaps serving
>as a translation point between limited groups)?

Most regions of the brain are made up principally of interneurons
(usually short neurons whose entire structure is confined to the
region), and shot through with projecting or pyramidal neurons which
span more than one region and carry 'information' between the
regions.

>I read recently that they are working with cybernetic implants to give
>vision to the blind, but that currently they are only capable of black and
>white pictures. or that they soon will be anyway. Since the computers we
>currently used are binary based, I wonder if we'll have to develop new
>computers that aren't binary based before obstacles, such as color in this
>example, can be overcome?

I could be wrong, but I think the earliest computers were analogue,
not binary. I seem to recall those used during WW2 to crack the
German Enigma codes were (although whether you could call them real
computers may be debatable-probably closer to dedicated
calculators). 

I do know that when one were matched against a mid 1990s
supercomputer it was about 14 times quicker at cracking the test
codes. So analogue can, at least in some circumstances be better
than binary.

As for colour, most of what we see is actually in B&W. We have far
more  B&W than colour receptors. And most of the time the brain
"sees" a lot more than the eyes do. It is very good at taking in low
resolution 'information,' connecting up the dots and lines and
filling them with colour.

It may be that only those who have had sight will get the most
benefit from cyber eyes, that the brain of those who have never seen
won't be able to fill in the gaps, or at least not as well. 

Age may also prove a factor, with the brains of those beyond their
early teens not being able to adapt properly. Certainly, this seems
to be the case with bionic ears where they now prefer to fit them to
young children, not adults.

                                              Zu






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