20 votes
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Is NMDA produced in the body?

(my comment reiterating the answer seemed useful, so I've reproduced it here) There are "NMDA receptors" in our body. There is not NMDA naturally in our body*. "NMDA receptor" is just a name people ...
Bryan Krause's user avatar
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16 votes

Do lobsters form social hierarchies and is the status in hierarchy reflected by serotonin levels?

The paper Peterson cites about serotonin and lobsters explicitly contradicts him in two major ways. First, although serotonin plays a role in aggression across many species, its role is not the same ...
E Tam's user avatar
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13 votes
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Why do Hot/Cold drinks taste sweeter once returning to room temperature?

Generally, cold suppresses sweetness. As an example, consider soft drinks that are usually served cold: they taste sweeter when warm (like you said with your examples of drinks). Our taste receptors ...
Ebbinghaus's user avatar
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11 votes
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Can acetylcholine leak away from the synapse and cause spasms?

The enzyme responsible for the breakdown of acetylcholine (Ach), i.e., acetylcholinesterase, rapidly degrades, and inactivates Ach in the synaptic cleft after release. This process is particularly ...
AliceD's user avatar
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9 votes
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Humans have Cannabinoid receptors. Does that mean we're meant to consume cannabis?

Receptors Any drug or compound with specific effects has a receptor. You can read about this general concept in Goodman and Gillman's The Pharmacological Basis of Therapeutics. Chapter 1 introduces ...
De Novo's user avatar
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6 votes
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What is the definition of an opioid, beyond that it's something that stimulates opioid receptors?

First there was opium. Then the active components of opium (morphine etc.) were defined and called opiates. Then the receptors for opiates were discovered, along with their endogenous ligands (...
Alan Boyd's user avatar
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6 votes
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If action potential is "all or nothing" then how are finely tuned signals sent from one neuron to another?

how is one type of neurotransmitter secreted rather than another Most neurons release a single major neurotransmitter. JM97 commented a link about cells releasing more than one, but that is talking ...
Bryan Krause's user avatar
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6 votes

Humans have Cannabinoid receptors. Does that mean we're meant to consume cannabis?

In addition to De Novo's excellent answer, I would like to add that sometimes, the fact that we have receptors for something is precisely a sign that we should not consume that thing. When it comes ...
Mowgli's user avatar
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5 votes

What controls gut motility?

When discussing the control of gut motility there is more to mention than the use of serotonergics and opioids - a number of peptide and nonpeptide neurotransmitters are important. Somatostatin and ...
Roby Vicary's user avatar
5 votes
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Why do classic psychedelics not cause withdrawal, despite high tolerance?

Short answer Withdrawal effects are generally associated with drugs that induce feelings of euphoria by stimulating the reward center of the brain, either directly (cocaine, morphine) or indirectly (...
AliceD's user avatar
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5 votes
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Is every neurotransmitter receptor an ion channel?

is every neurotransmitter receptor also an ion channel? No. There are two general types of receptors for neurotransmitters, ligand gated ion channels and receptors that activate second messenger ...
De Novo's user avatar
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5 votes
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Where are neurotransmitters secreted?

There are proteins (in truth, small peptides) released by neurons, but these are not the most typical or canonical type so I don't know where you got that information. Wikipedia has a list. Most are ...
Bryan Krause's user avatar
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4 votes
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How does receptor downregulation/upregulation work?

Both internalization (sometimes with degradation) and changes in gene expression can occur; the circumstances leading to the down regulation determine which (or both). It isn't necessary for receptors ...
Bryan Krause's user avatar
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4 votes
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How do different sensory stimuli differ in nerve signal?

I think the short answer to your question is that the contents of different types of sensory stimulation are communicated to different populations of cells in the brain (note this transmission is ...
Bryan Krause's user avatar
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4 votes
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Why do SRIs help in serotonergic neurotransmission?

Excellent question. Different neurotransmitters operate at different temporal scales (and even the same transmitter can operate at different temporal scales). Examples of the fastest-acting ...
Bryan Krause's user avatar
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4 votes
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Where does the initial action potential come from?

The very first evoked spike is most likely triggered by spontaneous activity, as even neurons with no synaptic connections are able to fire action potentials (Luhmann et al. 2016). Later in life ...
vkehayas's user avatar
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4 votes

difference between neurotransmitters and hormones

At heart, the distinction between neurotransmitters and hormones is how they are transmitted - not necessarily a difference in the chemicals themselves. Neurotransmitters are sent over synapses, ...
Jam's user avatar
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4 votes
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Inhibitory effect of GABA through GABA(A) receptors

Great question! This apparent contradiction has puzzled many neuroscience students before you. Short Answer: This is often called "shunting inhibition," in particular when excitatory and inhibitory ...
Bryan Krause's user avatar
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4 votes
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Is the ACh receptor more permeable to sodium ions?

Short answer No. There are differences in Na+ versus K+ permeability, but you have it backward: potassium is actually slightly more permeable; however, these differences are not the only factors ...
Bryan Krause's user avatar
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4 votes

Are neurotransmitters part of the endocrine system?

Short answer Synaptic signaling can be seen as a type of paracrine signaling, and is hence not an example of an endocrine system. Background Khan Academy has a nice accessible overview on this ...
AliceD's user avatar
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4 votes
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How does the dopamine spike from drugs compare quantitatively to pleasurable non-drug activities?

This review article [1] gives dopamine responses for rats (similar to the BBC article above) and includes references to the underlying studies: Sex/Food: 150% - 300% Alcohol/Ethanol: 190% (1g/kg) *...
Andy's user avatar
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4 votes

Can catecholamines degrade back into tyrosine, or, is synthesis irreversible? (in human body)

A glance at the relevant BioCyc entry tells us that each reaction in the catecholamine biosynthesis pathway is irreversible. The standard free energy change of each reaction—again from BioCyc—is given ...
Adhish's user avatar
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4 votes
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How do anticholinesterase pesticides kill nematodes?

Cholinesterase inhibitors and plant-pathogenic nematodes While it is true that cholinesterase inhibition does not affect gas exchange in nematodes, it does produce other effects by paralysing motor ...
Adhish'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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3 votes
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What is a starter cell?

Nice question - this terminology isn't referring to a special type of cell or anything, but to a peculiarity of the technique they are using. They are labeling a subset of cells with rabies virus; ...
Bryan Krause's user avatar
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3 votes

How long does a spiking signal last?

Effective integration time of a typical neuron is in the order of 10-100 ms. You might want to look into this classic paper (read it with a critical mindset): Shadlen, M. N. and Newsome, W. T. (1994)....
Memming's user avatar
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3 votes
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What is synaptic clearance?

"Synaptic clearance" is referring to the clearing of a neurotransmitter from a synaptic cleft. A synapse is a place where one neuron can stimulate another neuron. The tiny gap between the neurons is ...
mgkrebbs's user avatar
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3 votes

Understanding the brain: how are neurotransmitters released in the brain?

The release of neurotransmitters is a very specific type of SNARE mediated exocytosis. The action potential from the influx of sodium propagates along the axon and reaches the axon terminal, ...
FZG's user avatar
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3 votes

Why does excess dopamine activity in the pleasure centers results in less pleasure in schizophrenics?

Short answer The dopamine hypothesis includes brain regions with reduced dopamine transmission as well. The prefrontal cortex in specific has reduced dopaminergic activity and is implicated in ...
AliceD's user avatar
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