[Neuroscience] Re: Thought and firing neurons

chadmaester chad.d.johnson at gmail.com
Thu Jun 8 19:23:58 EST 2006


> In particular, a metabotropic transmitter/modulator can
> trigger a second messenger event that activates a system that can
> change gene activity.

What do you mean by "change gene activity?"

Can I ask where you've learned all these things (i.e., a specific
book(s))?

r norman wrote:
> On 8 Jun 2006 09:20:51 -0700, "chadmaester" <chad.d.johnson at gmail.com>
> wrote:
> >r norman wrot
>
> >> More seriously, the working out of brain function involves far more
> >> than neurons 'firing' action potentials.  There is an enormous amount
> >> of analog (continuously variable) signal processing going on in the
> >> microcircuitry of the dendrites and anaxonal or short axonal neurons,
> >> not to mention all the biochemical and molecular biological of the
> >> second messenger metabotropic synapses to account for.  All these
> >> factors probably play a larger role in establishing the phenomenon we
> >> call 'thought' than simple action potentials.
> >
> >Do you think neurotransmitters and secondary messengers are critical to
> >emotions?
> >
> >> Short term memory has many guises and is important for all aspects of
> >> neural function including sensory and motor processing.  There is no
> >> one single short-term memory store.
> >
> >When neurons are done firing, how is it that we can remember something
> >we recently thought of for at least a few moments afterwards? Are there
> >temporary connections formed somewhere?
> >
>
> Clearly the notion of neuromodulation and secondary messengers and the
> ancillary effects of second messengers (beyond simply causing ion
> channels to open to cause an electrical potential) are critical to
> emotions.   The nervous system really is not a simple computer whose
> operation depends on which cells are "active" (firing action
> potentials) and which are not.  The  background of cellular and
> biochemical activity is an integral part of the system.
>
> These events I am talking about are a critical part of the "memory"
> you are interested in.  Electrical events can perpetuate themselves
> for a short time in "reverberant circuits".  However the metabotropic
> transmitters and modulators produce changes in cellular activity that
> can last for a very long time.  Google "synaptic plasticity" or
> "synaptic modulation" or, especially "long term potentiation" for
> examples.  In particular, a metabotropic transmitter/modulator can
> trigger a second messenger event that activates a system that can
> change gene activity.  The activation or inhibition of specific
> proteins can then lead to permanent changes in cell structure and
> function.
>
> The electrical activity of neurons is intimately connected to this
> cellular activity.  Electrical activity mediated by those metabotropic
> chemicals (or by Calcium channels) can produce long-lasting changes in
> cellular metabolism and gene regulation.  These, on the other hand,
> can result in changes in membrane proteins, receptors and ion
> channels,  and hence in the production of electrical activity.  The
> electrical events and the cell physiology are all part of the story.
> That is why I originally said that looking only at action potentials
> is a small part of the picture of the nervous system.
>
> That being said, it is also true that many aspects of neural
> "computation" are produced purely or mainly by the electrical side of
> things (as in rscan's comments citing the early Hubel and Wiesel
> studies of vision as electrical responses to patterns of light.
> However, developmental and plastic changes are not included in this
> paradigm and, especially, Hubel and Wiesel's studies on the influence
> of experience on development in the visual system involve  these
> cellular changes as mechanisms.



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