"Richard Norman" <rsnorman at mediaone.net> skrev i melding
news:nvvm0u0lvmkmful2203kgvhbd6e9tvoje6 at 4ax.com...
> On 3 Dec 2001 06:03:23 GMT, dag.stenberg at nospam.helsinki.fi wrote:
>> >Richard Norman <rsnorman at mediaone.net> wrote:
> >> And don't even think about a synapse that actually DEcreases ion
> >> permeabilities!
> >
> >Well, but there are synapses that do so indirectly: an axon terminal may
> >release a transmitter that binds to a postsynaptic receptor that via a
> >G-protein in the membrane induces closure of a K+ channel, which is a
> >depolarizing, i.e. excitatory action.
> >
> >Dag Stenberg
>> Exactly. That makes defining just what is an "excitatory" or an
> "inhibitory" synapse very complicated. Let's see, its not the
> transmitter -- ACh and NE can do either. Its not depolarization vs
> hyperpolarization -- a Cl channel can depolarize but still be
> inhibitory. Its not the type of ion involved -- you have given a case
> of an excitatory synapse that affects K channels. So it is a little
> tricky. That is what makes neurobiology such fun. That is also what
> drives newcomers crazy.
Thanks for your last remark (from us non-experts).
Anyway, I got "Principles in Neural Science" last week.
Today I finished the appendices (B and C), which covered the blood-brain barrier and the
arterial system, respectively.
Although it was a little weak considering the Thalamus (which was strange), but then I
have the other one ("Exploring the Thalamus").
Anyway, if you have some experience in electronics, it doesn't come as a surprise
(inverted logic, and, or, nand+ nor etc.).
Although I must say that it is more demanding to follow the thread, if not just to
remember the various expression(s).
Brian
