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11 votes

Why are nerves blocked even though potassium channels are not blocked?

In general, action potentials are initiated by an inflow of Na+ that depolarizes the neuron. Only after that, K+ channels open up that re-polarize the membrane potential to get the neuron back in ...
AliceD's user avatar
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7 votes
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Is colocalisation of a protein with a presynaptic marker sufficient evidence to say that the protein is a component of axon terminals?

Colocalization of a protein with another structure is necessary but not sufficient to say that the protein is a component of that structure. Mixed into the concept of a structure's existence is the ...
Ryan's user avatar
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7 votes
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Functional unit

In biology, functional unit of a system refers to the smallest structural element that is capable of performing the tasks typical for that system (MP Hlastala, Physiology of Respiration). In the ...
Jan's user avatar
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6 votes
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Why do ion leak channels exist?

Check the parameters that go into the Goldman equation... it shows that permeability of ions is as important as their concentrations. If the permeability is zero, there is no potential. Because other ...
Bryan Krause's user avatar
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5 votes

Is colocalisation of a protein with a presynaptic marker sufficient evidence to say that the protein is a component of axon terminals?

Empirical science is not based on proof, but on evidence. No one study is the final word on anything. "Sufficient evidence" is entirely up to the person operating on the evidence and what ...
Bryan Krause's user avatar
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4 votes

Neurons: how does the brain reduce electromagnetic interference?

There is an extensive Q&A about the difference between brain waves and EM waves over on our sister site Psychology & Neuroscience: https://psychology.stackexchange.com/q/15222/14382 (though ...
Bryan Krause's user avatar
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4 votes
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Are living cells electrically neutral?

There are two ways to think about the "charge" of a cell. One way is by looking at all the chemical species inside the cell and calculating their sum charge. If you do this, you're going to ...
Bryan Krause's user avatar
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4 votes
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Understanding presynaptic and postsynaptic inhibition

Post-synaptic vs pre-synaptic inhibition Yes, inhibitory post-synaptic potentials (IPSPs) are always in the context of post-synaptic inhibition, because they are post-synaptic potentials. They occur ...
Bryan Krause's user avatar
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3 votes

Functional unit

"Functional unit" doesn't have a very specific meaning. It's mostly a term used to help biology students imagine organs as collections of parts. The entities named functional units in a textbook don'...
Bryan Krause's user avatar
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3 votes
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What causes sodium channels to open?

Sodium channels are primarily voltage-gated - these are the channels responsible for action potentials. Many other receptors are ligand-gated, and these are typically the signal that causes the ...
Bryan Krause's user avatar
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3 votes
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Relationship between membrane current and voltage in neurons

This is a bit of a strange way to plot out these data, I think Figure 3.2 is easier to understand, but basically these are data plotted from early voltage-clamp experiments trying to walk you through ...
Bryan Krause's user avatar
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3 votes

Can Neurons be connected in Series and will that pattern create huge voltage in human body?

In a typical nervous system, no, that's not how neurons are connected at all. Neurons have a voltage across their membrane, a potential difference inside versus outside of the cell. A "connection&...
Bryan Krause's user avatar
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2 votes
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When do the first neurons appear in humans?

Apparently, olfactory axons and GnRH producing neurons are among the first neurons that migrate from neural crest at around 39th day of gestation in humans (Cassoni et al., 2016). In rodents, ...
WYSIWYG's user avatar
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2 votes
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Why didn't the human Cerebrum evolve to have granule cells like the Cerebellum does?

By "cerebrum" I assume you really mean the cerebral neocortex, since the cerebrum includes other subcortical structures that themselves are quite distinct (e.g., the basal ganglia). Simply, the ...
Bryan Krause's user avatar
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2 votes
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Connectivity Relation between axon terminal synapses and dendrites

Synapses are pretty much one-to-one Here's some EM pictures of synapses, from Wikimedia commons: You should gather from these images that these are super organized structures. There's a dense, dense ...
Bryan Krause's user avatar
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2 votes
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Is there a difference between human neuron cells compared to those of other animals?

Not really. There really is little difference in neurons in mammal and indeed not much change across vertebrates. You have to go back all the way to jellyfish before you find major differences in ...
John's user avatar
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2 votes
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How are neurons selective towards specific stimuli?

Sensory receptors and neurons get their selectivity from physical processes and their position in space. For example, photoreceptor cells in the retina respond to light in a specific position in space ...
Bryan Krause's user avatar
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2 votes

Why are nerves blocked even though potassium channels are not blocked?

I don't know much about the effects of anesthetics, but I have taught basic nerve function at university level, so I hope I can help a little with that part. Potassium flow does not start an action ...
Michael Ladegaard's user avatar
2 votes

What is a polar plot of relative neural firing

If you map every spike of a neuron to the phase of an oscillatory process (in your case a 12 Hz sine wave) then you can plot an histogram of that phases. It's usual to plot the histogram in polar ...
heracho's user avatar
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1 vote

How does a neuron change its function, without changing its synaptic connections?

The keywords are Synaptic plasticity, LTP, LTD, and STDP, among others. The organelles includes release pools, receptors, scaffold proteins, etc. Actually there is a huge body of literature around ...
X Zhang's user avatar
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1 vote

Neurons: how does the brain reduce electromagnetic interference?

There are two aspects to this question. The first, dealing with EMR associated with AC generated in the usual range is already properly answered. However, in the case of mobile phone radio and wifi ...
jeremiah's user avatar
  • 309
1 vote

Vision and signal through the nervous system: Is it Frequency Shift Keying?

Frequency-shift keying is an electronic communications approach, part of a broader set of frequency modulation strategies for conveying information. These strategies relate to the difficulty in ...
Bryan Krause's user avatar
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1 vote
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The role of PCA (Principal Component Analysis) in recording neurons

Like vkehayas mentions in a comment, they're using it for spike sorting, as you've guessed. This involves both identifying signals from putative neurons (vs noise) and separating different source ...
Bryan Krause's user avatar
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1 vote

Can potassium ions depolarise neuron membranes?

Yes, this is a very basic neuroscience question, something that would probably come up in the first week of a neurophysiology class or unit. The polarization of the membrane at rest is due to cells ...
Bryan Krause's user avatar
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1 vote

Do voltage-gated channels in a neuron use ATP

No, they change conformation in response to voltage. Wikipedia has some general discussion of the gating process, as would any basic neuroscience textbook. The primary energy (ATP) cost of ...
Bryan Krause's user avatar
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1 vote

Is there a difference between human neuron cells compared to those of other animals?

As you mentioned yourself, there are differences in brain size, form and structure. This difference also affects the size and shape of cells, i.e. you won't find meter-long neurons in mice, but rather ...
KaPy3141's user avatar
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1 vote

Cumulative synaptic transmission delay

The brain is massively parallel. There are a lot of recurrent connections and feedback loops that are important for setting expectations, building a model of the world, and learning, but the pathway ...
Bryan Krause's user avatar
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1 vote
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Are synaptic boutons always located on axons?

Axonal boutons are named as such due to their shape. Dendro-dendritic synapses do not resemble this shape and are never referred to as boutons. It does not appear that synaptophysin is expressed on ...
vkehayas's user avatar
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1 vote
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What is meant by the term synaptic targeting?

PSD-95 is a protein located in the post-synaptic region inside a cell. In fact it's named for this, "post synaptic density-95" referring to the dense appearance of the post synaptic area on ...
Bryan Krause's user avatar
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1 vote

Are sensory mechanoreceptors and mechanical nociceptors the same type of neurons or are they different?

I don't know if this directly answers your questions, but I think some confusion may stem from an underlying misconception of receptor vs receptor cell. In most contexts (though not this one), '...
SmallFish's user avatar
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