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What part of the brain is responsible for conditioning the body to overcome a knee-jerk response such as pain. You can get people who find pleasure out of pain, is this something you're born with, or is there a specific part of the brain, that can alter how such a response is processed ?

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What part of the brain is responsible for conditioning the body to overcome a knee-jerk response such as pain.
This is a very tricky question. There is no one part of the brain responsible either for pain, or for overcoming it. Pain is a psychological state and it takes many different regions to produce the experience (collectively known as the pain matrix). It's more a function of circuitry than the activity of any one part.

 

You can get people who find pleasure out of pain,
Not really. Nobody finds pleasure in pain. One of the key elements in the definition of pain is that it is aversive (i.e. having been subjected to it, you will work to avoid it in future).

 

However, the stimulus itself is not pain, and people's responses to such stimuli are entirely subjective, so what might be painful to one is not necessarily painful to another. There are people who can get pleasure from intense physical stimulation that objective observers believe should be painful, or would be if they were subjected to it. You see the difference?

 

is this something you're born with, or is there a specific part of the brain, that can alter how such a response is processed?
As I said, there is no specific part. People are born with the basic 'wiring' for nociception (the detection and transmission of information pertaining to noxious stimuli), but this has little to do with the ultimate experience or the way people respond to it or cope with it.

 

As your thread title suggests, all that is down to conditioning. People are conditioned to associate different stimuli (and intensities of stimuli) with different outcomes and this determines basically what each stimulus means to an individual.

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Thanks Glider, and I entirely agree with the subjective part...I guess I was a little stumped in trying to word the question, because although pain is entirely subjective to the individual, the threshold still has to be overcome for somebody to become conditioned to an intense stimulus. So, a very young child would be much more sensitive to a stimulus, than they would if they grew to be in the SAS (for example) unless they had something inherently wrong with them.

 

So I suppose conditioning is more psychological, and like you said can't be pinned down to a specific part of the brain. I guess this really belongs in psychology in that case.

 

Slightly off topic, I remember hearing of a condition where pain (using the word at face value) is not experienced, so you could even fracture your arm, and no nothing about it...is this true ?

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Thanks Glider, and I entirely agree with the subjective part...I guess I was a little stumped in trying to word the question, because although pain is entirely subjective to the individual, the threshold still has to be overcome for somebody to become conditioned to an intense stimulus. So, a very young child would be much more sensitive to a stimulus, than they would if they grew to be in the SAS (for example) unless they had something inherently wrong with them.
I see what you mean. Bear in mind though that the pain threshold is as subjective as pain itself, and is not fixed.

 

A couple of years ago, I did some research in which I showed that simply altering the wording of a pre-test briefing resulted in people experiencing the second of two identical pain stimuli as either more painful or much less painful than the first (see attachment).

 

This basically shows that threshold is more to do with people's evaluations and beliefs concerning the situation and their short-term expectations concerning probable outcomes (as well as certain personality factors).

 

If you think about it, in those who reported the second stimulus as much less painful, it would have taken significantly greater stimulus intensity to reach pain threshold than it did only 20 minutes before. So, just by using words, I moved their threshold upwards significantly (and downwards in the others).

 

You can imagine then, that if the situation was intense enough, or if the stimulus was associated with something other than harm or a negative event or outcome that pain threshold might be moved beyond the usually expected 'norms', or removed entirely for a particular stimulus.

 

So I suppose conditioning is more psychological, and like you said can't be pinned down to a specific part of the brain. I guess this really belongs in psychology in that case.
Yeah, and a lot of what appears in Psychology has no place there. I don't know where people get the idea that Psychology consists solely of the dribblings of a bunch of crystal waving, tree-hugging hippies *sigh*:-( .

 

Still, The study of pain and nociception comes under the cognitive neurosciences, so It's ok here.

 

Slightly off topic, I remember hearing of a condition where pain (using the word at face value) is not experienced, so you could even fracture your arm, and no nothing about it...is this true ?
Yes, as you say in your next post, congenital or universal insensitivity (to pain). It sounds ideal, huh? Unfortunately, people with this condition rarely live beyond their 20s. I guess this is a good indication of the importance of the ability to fell pain.

 

Pain is not really the enemy. The nociceptive system is one of our oldest neurological systems. Even the fibres involved reflect this, being non-myelinated and only thinly myelinated (C and A-delta fibres respectively). Most of the processing to do with pain happens in the limbic areas of the brain. The neocortex is only to do with the discriminatory component of pain (i.e. it only allows us to determine the precise location, duration and intensity of the stimulus). Pain, or the ability to experience it, is adaptive and absolutely necessary. We're in a lot of trouble without it (as evidenced by people with congenital insensitivity). The real enemy is suffering.

 

that sounds like leprosy, I`m not sure if it extends to Bones though?
Me neither, but it's a good example. Most of the damage associated with leprosy (loss of fingers, toes and other tissue damage) is not down to the disease, it's down to damage caused by the individual (and subsequent infection) due to the insensitivity leprosy causes.

Williams et al 2004.pdf

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A couple of years ago' date=' I did some research in which I showed that simply altering the wording of a pre-test briefing resulted in people experiencing the second of two [i']identical[/i] pain stimuli as either more painful or much less painful than the first (see attachment).

 

This basically shows that threshold is more to do with people's evaluations and beliefs concerning the situation and their short-term expectations concerning probable outcomes (as well as certain personality factors).

 

If you think about it, in those who reported the second stimulus as much less painful, it would have taken significantly greater stimulus intensity to reach pain threshold than it did only 20 minutes before. So, just by using words, I moved their threshold upwards significantly (and downwards in the others).

 

You can imagine then, that if the situation was intense enough, or if the stimulus was associated with something other than harm or a negative event or outcome that pain threshold might be moved beyond the usually expected 'norms', or removed entirely for a particular stimulus.

 

Very interesting, thanks very much...I havn't had time to read the paper in full, but hopefully later on this evening. It seems even in an uncontrolled environment e.g the split second when somebody scalds themselves on an iron (so they are not expecting the pain) the reaction time will differ, how the person will cope with the outcome, and any form of previous conditioning to similar situations would be accountable.

 

I guess I was thinking whether there is such a thing as an 'absolute' threshold, given certain circumstances, and a tight limit on the time scale in which the reaction to pain is measured...so the split second knee jerk reaction. I guess it's quite hard to imagine that even when the intense stimulus is not expected...someone could be capable of keeping their hand firmly pressed on the hot plate of the iron, despite not expecting it.

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I've heard a lot of stories about PCP, some possibly myths (isn't it a dog tranquilizer)...however, I do find it fascinating that an inherent survival process such as pain (one we cannot do without), can be overcome by thought alone. It does illustrate quite nicely what the brain is capable of, and possibly holds other implications...but before anyone starts, that's a different debate entirely.

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Very interesting, thanks very much...I havn't had time to read the paper in full, but hopefully later on this evening. It seems even in an uncontrolled environment e.g the split second when somebody scalds themselves on an iron (so they are not expecting the pain) the reaction time will differ, how the person will cope with the outcome, and any form of previous conditioning to similar situations would be accountable.
In this instance, reaction time has to do with the reflex arc rather than any deliberate, volitional action.

 

The reflex arc is formed by interneurons in the spine, that basically connects the incoming afferent pathway to the outgoing efferent (motor) pathway. Any stimulus of sufficient intensity will trigger the reflex arc resulting in a very basic and non-volitional withdrawal action.

 

Because this happens at the spinal level, it is very fast (which is adaptive, helping to minimise damage) and completely automatic, so it doesn't really have anything to do with reaction times. The reflex action will have been performed before the sensory signals reach the brain. I.e. you feel the burn of the iron after you have moved your hand. Compare the relative conduction velocities: The primary afferents associated with pain (C and A delta fibres) conduct at 0.5-2.0 and 2.0 - 12.0 metres per second respectively, whereas larger afferents conduct at anything between 80 and 120 metres per second.

 

As the emotional-motivational component of pain is a major one, the shock of a reflex (i.e. startle) often compounds the experience. This is why for example, young kids will usually cry when they fall over, even if they are not hurt. It's the shock.

 

I guess I was thinking whether there is such a thing as an 'absolute' threshold, given certain circumstances, and a tight limit on the time scale in which the reaction to pain is measured...so the split second knee jerk reaction. I guess it's quite hard to imagine that even when the intense stimulus is not expected...someone could be capable of keeping their hand firmly pressed on the hot plate of the iron, despite not expecting it.
No, you're right, they couldn't (unless they were congenitally insensititive).

I think you're thinking about two separate things here. Pain threshold and reflex.

 

Pain threshold depends upon many factors including stimulus intensity. As such, it is not fixed and there is no absolute. You have to bear in mind that the relationship between noxious stimuli (e.g. stimuli intense enough to cause tissue damage) and the experience of pain is correlational, not causal. If it were causal, the same stimulus would always result in the same experience (it doesn't), tissue damage would always result in pain (it doesn't), pain would never happen in the absence of stimuli of that intensity (it does).

 

Reflex is non-volitional and automatic. It is also independent of experience because it will often have taken place before the experience. Normal human reaction time (which is different to reflex as it involves processing) has a mean of around 500ms. The most basic (monosynaptic) reflex responses occur at around 50ms. Most reflexes based on the startle response are more complex (as they're not based simply on an interneuron) and so take longer, but still much faster than 500ms.

 

The key element in many reflexes (those based on the startle response) is that the stimulus in unexpected (i.e. the incoming signals do not match your current model of reality). For example, you're out camping. It's night and you're all sitting around the fire having a blast. You reach behind you for another cold tinny.

 

In model 1, your hand contacts something cold, and wet with condensation. This matches your model of reality, no problem. Have a tinny.

 

However, in model 2, your hand contacts something cold, wet and moving. In this case, the incoming information does not match your model of reality and you're on your feet and running before you've identified the object.

 

This is an adaptive (startle) reflex response. It is automatic and it doesn't require the stimulus to be intense, just unexpected. Imagine the hot iron thing you mentioned. The unexpected element here is that you weren't expecting to touch it. Imagine of some joker had put the iron in the freezer for an hour. You believe the iron is not plugged in and therefore cold. However, when you touch it, yes it is cold, but extremely (and unexpectedly) cold, and you will reflexively withdraw.

 

The brain holds your model of reality and sets the level for expected incoming information. The comparison between expected and actual intensities of incoming infomation is made at the spinothalamic level. Thus the level of processing is very basic but information doesn't need to go higher than that to elicit the response.

 

However, this reflex response can be overridden. If someone picks up an unexpectedly hot cup of coffee in someone else's house, they will often do the silly dance and try to juggle it to the nearest surface, where there immediate urge would be to drop it (although, if it's hot enough, they will just drop it).

 

Basically, if you wanted to use reflex as a measure of pain threshold, then your measure would be invalid, you would not be measuring pain threshold. It doesn't take painful stimuli to elicit a reflex (see the cold tinny example). Moreover, if the stimulus was expected, it wouldn't elicit a reflex anyway, and depending on circumstances, certain reflexes can be overridden.

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Glider, I couldn't of asked for a better explanation, so thanks again. I must admit I always associated a reflex action from something potentially painful (especially something very hot) as a reaction to pain itself. I guess this is why you can walk across hot coals (a few friends and myself) have actually done this. Although I knew there was a delay before the pain was processed, if I accidentally stepped on a hot coal without knowing it was there, I would immediately jump away from it...rather than consciously raising my foot quickly to avoid the pain, if I stepped on it deliberately. I guess it's though microseconds of reaction between reflex and actual pain, and why I couldn't see the distinction. But obviously they're completely distinct situations, and reactions.

 

By the way, I urge anyone not to walk on hot coals to try this out...I managed to get a small glowing rock trapped between my toes, and it was incredibly painful.

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You're welcome. Glad it helped.

 

I must admit I always associated a reflex action from something potentially painful (especially something very hot) as a reaction to pain itself.
A reflex is to protect you from something potentially harmful. There's a subtle difference because whilst harm is generally associated with pain it ain't always so.

 

Reflexes (and startle responses) are fast, whilst pain is quite slow. Think about the times you've stubbed your toe (everybody has done this). First you get the shock, then you get that brief split second of calm where you realise that it's really going to hurt, then it does.

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  • 6 months later...

Pehaps a misplased post! So,eones quot `I haer and i forget, I see and i remember!'Phylosophy: snail slow with Coclear shell Ì hear'BEE SEE i sew and remeber eons WASp owh god!saw pawsswap, the logic of human languague ma be vital to creatues in the future, but i woundnt want to confuse you, prolly don't realize or a bee sigion sock of grasp as tp what im on about ha? enjoy peoples!

 

chris rivers!

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  • 2 months later...
I've heard a lot of stories about PCP, some possibly myths (isn't it a dog tranquilizer)...however, I do find it fascinating that an inherent survival process such as pain (one we cannot do without), can be overcome by thought alone. It does illustrate quite nicely what the brain is capable of, and possibly holds other implications...but before anyone starts, that's a different debate entirely.

 

PCP blocks the NMDA receptor at the phencyclidine binding site to induce analgesia. Its relative is ketamine, a widely used anesthetic in humans.

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What part of the brain is responsible for conditioning the body to overcome a knee-jerk response such as pain. You can get people who find pleasure out of pain, is this something you're born with, or is there a specific part of the brain, that can alter how such a response is processed ?

 

i don't think this has been mentioned but i think the pleasure-pain responce can be partially explaned by the production of endogenous opioids... endogenous opioids, e.g. endophins, stop the activation of second order neurones in the spinothalamic pathway (the 'pain pathway') and can also affect mood... so if you are given a continuous painful stimulus... you'll find that after a while the pain will reduce... this can be explained by production of endogenous opioid decreasing the activation of the pain pathway...

 

i think that adreanline can affect pain sensation but i can't remember how... for example, you here of people who suffer very painful injuries in wars and do not complain of feeling any pain until several hours afterwards...

 

but i'd be careful when saying things like 'some people find pleasure with pain'... people who do things like slitting their wrists tend to have real issues... they often do it as a way of escape or as a cry of help and it doesn't necessarily mean they are getting any pleasure out of it...

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so if you are given a continuous painful stimulus... you'll find that after a while the pain will reduce... this can be explained by production of endogenous opioid decreasing the activation of the pain pathway...

 

Ok, but I'm not sure that's relevant...as already mentioned, pain is subjective so whether that process is inherent in everybody, it doesn't mean that particular process is a gauge to understand the level of pain an individual is enduring. I don't think that would give a clear indication of how an individual becomes conditioned to stimulus.

 

but i'd be careful when saying things like 'some people find pleasure with pain'... people who do things like slitting their wrists tend to have real issues... they often do it as a way of escape or as a cry of help and it doesn't necessarily mean they are getting any pleasure out of it...

 

Sorry, I didn't make that clear, I had sadomasochism and similar practices in mind.

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stop the activation of second order neurones in the spinothalamic pathway (the 'pain pathway') and can also affect mood.

 

Also painful stimuli travel up the spinomesecephalic tract which can cause increased dopamine release in the nucleus accumbens so I would argue some people do find pain pleasurable (however I am not one of them....)

 

Also, painful stimuli will traverse the spinoreticular tract to activate the RAS and increase awareness.

 

Lastly, noxious (painful) stimuli travel to the dorsal horn via A-delta (fast pain) and C fibers (slow pain) so there is a fast component to pain. I don't know about you but I just cracked my toe going to the bathroom and it hurt immediately. A-delta and C fibers synapse in the Rexed Lamina onto second order neurons (the spinothalamic, spinoreticular, and spinomesecenphalic tracts) and ascend rostrally to the thalamus onto a third order neuron.

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