Apr
11
comment Why are amino acids in biology homochiral?
@TomD ha, fair enough. Oversimplifications aside, though, I still like the piece because my memory is that they do a good job giving an intuitive feel for what chirality is and its effects. Of course, its likely that they make more frustrating oversimplifications and I missed them or forgave them in my rapture that a popular show was willing to dig pretty deeply into an idea like chirality for entertainment purposes. Sometimes Radiolab makes major missteps, but in general, I think their stuff is pretty solid as far as popular accounts of tricky scientific concepts go.
Dec
14
awarded Yearling
Dec
14
awarded Yearling
Nov
2
comment Distribution of synaptic connections
I don't have time for a full answer, but here is a study on the hippocampal CA1 pyramidal neuron that makes an exhaustive catalog of all synapse types and locations: Megías, M., Z. Emri, T. F. Freund, and A. I. Gulyás. “Total Number and Distribution of Inhibitory and Excitatory Synapses on Hippocampal CA1 Pyramidal Cells.” Neuroscience 102, no. 3 (2001): 527–40. I know such papers exist for a few other cell types. This paper might provide a lead for finding those too.
Nov
1
comment Differences between synaptic connections
@Jean-Paul Yes, location matters. In general, the spatial and temporal pattern of synaptic activation matters a lot. Two synapses activated at the same time on different dendritic branches will have a different effect from two synapses on the same branch. Two synapses on the same branch will have a different effect depending on the order of activation. Good rule of thumb for thinking about neural computation: if something can vary, it probably matters (and if it doesn't matter, there is probably a very interesting story about how the neuron ignores the variation).
Nov
1
comment How do neurons inverse an action potential?
@Jean-Paul Close, but with one major misunderstanding. In this reflex, the flexor muscle is not flexed (contracted). It is being relaxed by the reflex. How does this work? In the diagram, activating the E neuron contracts the extensor muscle, activating the F neuron contracts the flexor muscle. No activity in these neurons means the corresponding muscle is relaxed. By inhibiting activity in the F neuron, the interneuron indirectly causes the flexor to relax. All the connections in the diagram are excitatory, except for the interneuron to F neuron connection which is inhibitory.
Nov
1
answered Differences between synaptic connections
Nov
1
revised How does an inhibitory synapse communicate to the cell body of a neuron?
clarifying (hopefully) that location is not always compensated by synaptic strength
Nov
1
comment Differences between synaptic connections
I wrote that linked answer. I did not mean to imply that synaptic location is always compensated by local potential change.
Nov
1
comment How do neurons inverse an action potential?
@Jean-Paul Yes, a neuron will release the same set of transmitters at all of its synapses--often it will release just one neurotransmitter, but sometimes two or more at the same time. An inhibitory interneuron will not, for instance, release an inhibitory transmitter onto one cell and an excitatory transmitter onto a different cell. This is known as Dale's principle (en.wikipedia.org/wiki/Dale%27s_principle).
Sep
2
comment How do the brain and nerves create electrical pulses?
@Probably I'm building a simplified model of a neuron in the answer. When I say "we add" I mean "add this to your mental model of the parts of the system".
Jun
9
awarded Caucus
Jun
9
reviewed Approve suggested edit on How much heat can a human sustain?
Jun
9
asked How to get parent element of embedded svg in DOM?
Apr
1
awarded Good Answer
Mar
29
awarded Supporter
Mar
6
awarded Necromancer
Oct
24
awarded Custodian
Oct
24
reviewed Approve suggested edit on How does the ebola virus attack?
Oct
24
reviewed Close What kind of technology is required for plant seed DNA printing?
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