Reputation
2,154
Top tag
Next privilege 2,500 Rep.
Create tag synonyms
Badges
8 23
Newest
 Caucus
Impact
~26k people reached

Feb
5
comment Extraretinal photoreception in mammals?
Possible duplicate: biology.stackexchange.com/q/700/72
Feb
5
comment Extraretinal photoreception in mammals?
-1. It is well-established that opsins are expressed widely, but their functions are not known. It hasn't been convincingly shown anywhere that human opsins confer light sensitivity to any cells other than those in the retina. The knee study you mentioned has been refuted (see my comment here: biology.stackexchange.com/a/704/72). Also, a point of nomenclature, photoreceptors are cells that are sensitive to light, and opsins are called photopigments when they are bound to a chromophore and are sensitive to light.
Feb
2
comment What is the point of being selection-free?
I agree that they are trying to demonstrate a method that will be applicable for in vivo gene therapy. The results are suggestive of some rate of efficacy for in vivo repair. However, an 18% fraction of repaired cells in a dish does not point to, or even imply, an 18% fraction of repaired cells in a body.
Feb
1
comment What is the point of being selection-free?
-1. "This implies that if their treatment were applied to living tissue, 18% of the cells would be repaired in situ." Not at all. If only it were true that findings in a dish could draw such a straight line to results in the body!
Jan
29
revised Do adjacent axons in a nerve influence each other?
added 562 characters in body
Jan
29
answered Do adjacent axons in a nerve influence each other?
Jan
25
comment Why have humans evolved conciousness?
-1. The substantive part of this answer assumes the common misconception that only humans are intelligent and conscious, and that we somehow know this for a fact.
Jan
25
comment Why have humans evolved conciousness?
-1. Your question and comments are philosophical, not biological, and therefore not appropriate for this site. You seem to believe that evolution can't possibly explain it, and therefore there is really no science to be discussed. Read up on the philosopher David Chalmers, who agrees with you. Then read up on his main rival, Daniel Dennett. Note that when you get into these sorts of questions, your intuition about whether you "know" that you are "self-aware" and how to "prove" it are destined to fail.
Dec
14
awarded  Yearling
Nov
29
awarded  Revival
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