Christian Wilms <cwilms at stud.uni-frankfurt.de> wrote:
> If a so called "post-synaptic potential" is negative (inhibitory) or
> positive (excitatory) depends alone on the neuron, which recieves the
> signal (the so called "post-synaptic cell). The cell-membrane of this
> neuron contains ion-channels which function as receptors. If these are
> permeable for positively charged ions (Na+, K+, Ca2+), the potential
> will be excitatory, if they are negative (Cl-), the potential will be
> inhibitory. ....
> The direction an ion will move, when a channel permitting it to permeate
> is opened depends on the orientation of the driving force for this ion.
While your description is correct in most aspects, it does contain the
inaccuracies that
1) increasing the permeability for K+ will cause inhibition, and
decreasing it excitation, because the driving force for K+ is normally
such that it will flee from the cell, thus hyperpolarizing = inhibiting
the cell
2) increasing the permeability for Cl- will always cause inhibition, but
this can occur without any change in membrane potential (because of
"short-circuiting")
Dag Stenberg
