2,046 reputation
521
bio website github.com/yamad
location Boston, MA
age 29
visits member for 2 years, 10 months
seen Sep 25 at 20:55

PhD candidate in neurobiology/neuroscience. Current research focused on membrane electrophysiology.


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
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.
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
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
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
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.
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.
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.
Apr
24
comment What is meant in biology by the term “evolved”?
@KonradRudolph Do you mean that "more complex" has the same problems as "more evolved"? Or rather that it has the same problems as "more primitive"? Can you expand? What phrase do you prefer? I think "more complex" is very near to what people actually want to say when they use the term "more evolved." It does come with a bit of a value judgment about what complexity means, but I have a hard time thinking of a phrase that has much less baggage. If one is careful to specify the dimension, I think it can be reasonable to discuss the relative complexity of different systems.
Apr
5
comment Soma-soma paired neurons
Exactly right, they prepare (or setup) the cells in a particular way so that they can study them later. For instance, here they are removing the neurons from the snail and putting them together in a dish. Then they add a solution that encourages the synapse to form. As you might imagine, any given preparation will be good for investigating some things but bad for other things. A major part of experimental design in biology is choosing the right "preparation."
Apr
5
comment Brain + ethanol experiment suggestions needed
@HarroldCavendish: Can you explain more about what this experiment is for? Are you trying to do a PSA about the dangers of alcohol? What sort of experimental background do you have?
Apr
5
comment Brain + ethanol experiment suggestions needed
+100 for noting the requirement of a live animal and how non-trivial the proposed experiments are
Mar
20
comment Why can cones detect color but rods can't?
@nico There is a large body of literature with that kind of data. King-Wai Yau, Denis Baylor, and W.A.H Rushton are good guys to look out for if you want the historical data. For example, here is a lecture by Baylor with some ephys data. This one has amazing data on the response of rods to single photons! Mike Do and King-Wai Yau have great data on the responses of photosensitive retinal ganglion cells.
Mar
20
comment How does “be altruist to those who are similar to you” evolve?
@JimThio My objection to this question stands. I understand that your questions stems from your political beliefs, but your examples make this question argumentative.