20
votes
Accepted
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 ...
- 44k
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 ...
- 822
13
votes
Accepted
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 ...
- 2,603
11
votes
Accepted
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 ...
- 52.3k
7
votes
Accepted
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 ...
- 8,751
6
votes
Accepted
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 (...
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6
votes
Accepted
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 ...
- 44k
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 ...
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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 ...
- 407
5
votes
Accepted
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 (...
- 52.3k
5
votes
Accepted
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 ...
- 8,751
5
votes
Accepted
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 ...
- 44k
4
votes
Accepted
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 ...
- 44k
4
votes
Accepted
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 ...
- 44k
4
votes
Accepted
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 ...
- 44k
4
votes
Accepted
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 ...
- 1,198
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, ...
- 1,515
4
votes
Accepted
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 ...
- 44k
4
votes
Accepted
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 ...
- 44k
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 ...
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4
votes
Accepted
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) *...
- 61
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 ...
- 1,297
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 ...
- 44k
3
votes
Accepted
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; ...
- 44k
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)....
- 3,080
3
votes
Accepted
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 ...
- 9,024
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, ...
- 183
3
votes
Accepted
What stimulates a nociceptor?
All of these are affected by specific characteristics of the nociceptors.
Nociceptors are only sensitive to high pressure. The low pressure stimulus would only stimulate mechanoresceptors which ...
- 4,669
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 ...
- 52.3k
Only top scored, non community-wiki answers of a minimum length are eligible