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Nov
28
comment Action Potential Distribution On Synapses
@Armatus, the ions that flow in through ion channels during the action potential are almost certainly not the same ions that carry current axially to depolarize adjacent sites. The charge travels (that's what current is) but the ion fluxes are local.
Nov
28
comment Action Potential Distribution On Synapses
Threshold is not fixed, even within a single neuron over short periods of time. Fundamentally, threshold is reached when enough voltage-gated sodium channels open so that a rapid depolarization occurs--that is, when inward current is much greater than outward current. When this occurs is a complicated function of membrane resistance, leak currents, the recent history of the membrane, other inward currents present, the kinetics and voltage-dependence of outward currents, etc., etc.
Nov
28
answered Action Potential Distribution On Synapses
Nov
28
comment How do neurons form new connections in brain plasticity?
Like @nico says, there is a lot of literature on dendritic "reshaping" (see, for instance, biology.stackexchange.com/q/8/72). I'd say that dendritic reshaping is discussed with about as much frequency as axonal reshaping.
Nov
28
revised Does the speed of electrical impulses through neurones decrease with age?
added 250 characters in body
Nov
28
answered Does the speed of electrical impulses through neurones decrease with age?
Nov
28
comment Action Potential Distribution On Synapses
Can you revise your question? I am not sure what you mean when you say the "whole 40 mV is distributed" versus "a total 40 mV" which is "not there."
Nov
28
comment How and where, in the human brain, are memories stored?
For a little more on ways in which the nervous system is plastic, see my answer here biology.stackexchange.com/a/1359/72
Nov
28
answered Is nicotine toxic to humans?
Nov
22
awarded  Nice Answer
Aug
25
awarded  Good Answer
Jun
19
awarded  Enlightened
Jun
7
comment Understanding Membrane / Resting Potential from the perspective of ions?
The resting potential is only validly called an equilibrium potential in a system containing only one ion species. Of course, cell environments are composed of several ions so the resting potential is not described by any equilibrium potential, because (as you say) the system is at steady-state rather than equilibrium. A more general term is "reversal potential" which describes the potential at which net current switches sign (e.g., inward to outward). The concept of reversal potential simplifies to a Nernst/equilibrium potential in single ion cases, but also covers multiple ion cases.
Jun
6
revised How and where, in the human brain, are memories stored?
added some references
Jun
6
revised Understanding Membrane / Resting Potential from the perspective of ions?
Added neuroscience tag
May
9
comment Why do neurons die so quickly (relative to other cells) when deprived of oxygen?
+1. Neurons use a lot of active transport pumps that consume ATP to maintain ion gradients and to shuttle neurotransmitters.
May
9
answered Could we transmit smells electronically?
Apr
28
awarded  Nice Answer
Apr
26
answered Can one dendrite pass through another?
Apr
24
comment What is meant in biology by the term “evolved”?
@KonradRudolph I agree with you in general, and I was not advocating using "more complex" when comparing whole organisms. But I stand by using "more complex" when discussing specific features. It's true that complexity is a flexible ill-defined concept, but at least a speaker can specify how they are using the phrase. I think it's important to have some way to express the concept of relative complexity, which is meaningful if defined for a particular domain/feature.