What happens in the brain when we feel pleasure or pain?

[kolleamm]

From what I understand dopamine is released when we feel pleasure but how exactly does it interact with the brain? Does it spread to only a small space or a much bigger one?
I wonder the same for pain too.

 

[Bystander]

https://en.wikipedia.org/wiki/Endorphins

See also: "ex"-dorphins, "lost dorphins," Little Dorphin Annie.

 

[DaveC426913]

This is pretty Googleable (it's a word).
What have you found so far, and what specific questions didn't your research answer?

 

[BillTre]

From what I understand dopamine is released when we feel pleasure but how exactly does it interact with the brain? Does it spread to only a small space or a much bigger one?
I wonder the same for pain too.

Your query, addresses a mix different mechanisms at different levels of explanation.

dopamine is released when we feel pleasure but how exactly does it interact with the brain?

Although certain brain areas have been identified with certain aspects of behavior, I don't think there is a good understanding how how the brain's functioning as a conscious entity is affected by to cause it to feel pleasure. That is to say what is the difference between a happy and not happy brain state is not (to my knowledge) defined.
This is a psychological/brain physiology relationship.
Alternatively pleasure can be interpreted as the internal psychological experience of positive reinforcement, and the positive reinforcement can be considered from a behavioral/brain physiology perspective.

Does it spread to only a small space or a much bigger one?

Dopamine is found in several areas of the brain and is used in different functional mechanisms for different purposes in the brain.
One of those functions involves positive reinforcement and/or pleasure.

Dopamine is a neurotransmitter. Typically transmitters are released from the ends of a neuron's axons. Axons are extensions from the neuron's cell body. They can be long or short.
The axons of neurons can be:

• short (as in local interneurons)
• or can go far away in the brain (these are projection neurons, projecting axons to distant targets). Thus their signals may cover a lot of area in the brain. Dopamine neurons are like this.

Transmitter release sites:

• Transmitters can be released in tight association with a post-synaptic target cell. Rapidly diffusing a short distant to receptors on it's target cell in about 2 milliseconds.
• Sometimes the post-synaptic target is the pre-synaptic terminal of another cell. This can quickly have the effect of modulating the ability of the other pre-synaptic cell's activity to evoke its release of transmitter.
• Alternatively, the neuron's release site can be loosely associated with it target cells, so the released transmitter will (relatively) slowly diffuse to a wider field of targets over a longer time scale. Kind of like a hormone (a neuro-hormone).

My recollection is that transmitters like dopamine, in response to "pleasureable inputs" (or positive reinforcements) are released at at several places in the limbic system (a complex of interacting brain areas involved in emotional behaviors).
Although the dopamine may have effects in different areas, together they would have an overall effect of positive reinforcement or pleasure.

 

[atyy]

Since @BillTre answered the first part of your question, I'll give a few pointers for the second part about pain.

For normal sensing of pain, like when you are pricked by a needle or touch a hot stove, those depend on special pain-sensing neurons in the periphery. So pain has a special, separate pathway at the periphery. Whether pain also remains a separate pathway in the brain is unknown (most of us think it isn't, but imaging of brain activity doesn't have enough resolution to settle the question).

It is difficult to induce pain by stimulating the brain without stimulating the peripheral pain-sensing neurons, which is why it is often said the brain has no pain receptors, and one can operate on the brain without inducing pain. There are pain-sensing neurons in the meninges, the membranes covering the brain.

However, it is possible to produce sensations of pain in the brain by stimulating in the secondary somatosensory cortex (SII) and the insula.
Stimulation of the human cortex and the experience of pain: Wilder Penfield's observations revisited
Laure Mazzola, Jean Isnard, Roland Peyron, François Mauguière
Brain, Volume 135, Issue 2, February 2012, Pages 631–640
https://academic.oup.com/brain/article/135/2/631/261811

At a rough simplistic level, there are separate pathways in the brain for pain "sensation" and pain "unpleasantness".

It is possible to feel pain unpleasantness without being able to localize precisely the source of the pain, which is consistent with the idea that the pain "sensation" pathway can be damaged without damaging the pain "unpleasantness" pathway.
Pain affect without pain sensation in a patient with a postcentral lesion.
Ploner M1, Freund HJ, Schnitzler A.
Pain. 1999 May;81(1-2):211-4.
https://www.ncbi.nlm.nih.gov/pubmed/10353510

It also seems possible to some experience pain "sensation" without experiencing pain "unpleasantness"
Pain affect encoded in human anterior cingulate but not somatosensory cortex.
Rainville P1, Duncan GH, Price DD, Carrier B, Bushnell MC.
Science. 1997 Aug 15;277(5328):968-71.
https://www.ncbi.nlm.nih.gov/pubmed/9252330

 

[kolleamm]

Thank you for your well detailed responses. I want to have a really good understanding of the brain so that perhaps I could understand how consciousness arises, if that's even possible. That has been something I've wondered about for years.

 

[atyy]

Thank you for your well detailed responses. I want to have a really good understanding of the brain so that perhaps I could understand how consciousness arises, if that's even possible. That has been something I've wondered about for years.

My suggestion is to stay away from asking about consciousness on PF. Many neuroscientists (and lots of other people) are of course personally interested in consciousness, but we don't even know what an answer would look like, so it is not addressed in technical forums here or among professional neuroscientists (maybe at beer after work).

 

[DaveE]

In addition to the complexity of the consciousness question that @atyy referred to, a lot of people will avoid the discussion because there is a lot (really A LOT!) of crap out there associated with it; Deepak Chopra and such.