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Salience Theory: What is pain?

This morning I awoke to find a message from a Facebook user (who I am not friends with as yet) regarding the subject of pain:



"Spekulation: Pain: When the parameters upholding consciousness leaves the definition space for those parameters. Tickeling and pleasure: When you travel along the rand of the definition space of consciousness. Of course, the definition space changes as the neuroplasticity redefines how singlas are processed, hence pain happens when signals deviate too quickly from the normal. Do you know of any hypothesis which comes close to the above?"


Immediately the problem in this definition can be identified by realizing that biologically pain is truly a spectrum of alerts and is not a critical threshold where some system goes from signal to noise as would be the case if it were a rapid deviation from "normal" (however that is defined).

Biologically the pain receptors are distributed across the body along with other sensors that can identify pressure. The pain processing pathways and the somatosensory (pressure) processing pathways are therefor different to some degree. What degree would they need to be different in salience theory in order to be useful for consciousness without being terminal to it as asserted in this question is what is most important. It should be obvious that if consciousness were turned off as it were when any pain signal was received we'd have a hard time staying conscious. The function of TRP based molecules revealed in recent research show clearly how finely resolved is the experience of pain.



Pain sign ranges from notification to attention to continued awareness to agony. In the salience theory the dynamic cognition cycle divides dimensions of sensory experience into those that are externally driven and those that are internally driven. At first I was unsure of where pain actually went as it seemed to be triggered by both external and internal sensory factors, for example an obvious external factor that can induce pain is falling off a bike and obtaining bruises, conversely and important internal sensory factor that can induce pain is simply being hungry, the build up of acid in an empty stomach can lead to crippling pain that forces an individual to seek out food to quench.

So from this thought experiment it seems that pain is actually an input sensory dimension that can be triggered internally (we can cause pain to ourselves!) to some degree there seem to be pathways in place to subtract pain when we are causing it to ourselves (for example the mechanism by which self tickling is rendered moot) so there is some necessary feedback in the processing of the pain signal that enables this by attenuating self enabled sensations. However, the fact that pain is triggered by both told me immediately that in fact it was a salience factor akin to emotion. So how would it look like in salience theory?

Let's look at the simple Dynamic Cognition Diagram:







In this diagram,. pain would be triggered either by internal or external causation factors as previously described so where would it be in the cycle? It should be clear that because pain is used to inform action it would be a critical part of salience determination at step 3. The reason again is clearly shown by example to physiology, there are people who have varied ability to sense pain!

The pathologies draw mostly around the pain receptors not being formed at the nerves in the various locations they are distributed across the body and insensitivity to any external forces leading to various types of damage that people with properly functioning sensors don't exhibit. However, the pain receptors send the signal and salience indicates the importance of that signal.

It appears that since there are multiple sensors dedicated to different types of somatosensory experience (pain, pressure, temperature) all have a common salience module.

The subtraction of pain signalling from a self tickle indicates this module labels autonomic action differently from external action, there is likely a similar muting of temperature signals and pressure signals to prevent us from accidentally hurting ourselves in all three aspects.

In salience theory each is given it's on scale of gradation which would then enable feedback and labeling in the comparison stage that can then be used to inform goal selection for committing some sought out action. In the case of these signals this would be as a factor to modulate the cognitive selection process to bias to those options that are away from those that may be causing or have caused pain in the past.

I assert that this modulation is high resolution, dynamic across time in terms of the intensity of the signal reported but static as it is stored with memories associated with past experience. Comparison then simply results from setting a direction per compared salience factor associated with a stored memory versus an incoming experience in a given external dimension (vision, taste, touch (body map), smell,hearing) and then selecting either a stored option that has worked in the past toward achieving the optimal salience goal (if hot, take action to reduce heat. If hungry take action from evaluated options to reduce hunger..etc.).

A recent paper put forward a mechanism on how the cortex proceeds with goal selection that precisely matches with the hypothesis described for comparison in salience theory save for the fact that the paper had no means of describing the importance of salience itself.

A complex dynamic cognition diagram that I am working on attempts to provide these fine details of feedback between the salience module (including similar systems for metering and labeling of emotional import which a separate team has recently realized is granular just as I hypothesized years ago while forming salience theory) that diagram when finished will be the basis of my writing code to create a dynamic cognitive agent a some point in the near future.

That said, the assertion of the original question of pain being simply a threshold switch is obviously wrong it is a far more complex entity that has modes which are very important during conscious evaluation of salience for action, it can achieve levels of intensity that totally over ride actions that bias away from the pain reduction signal and thus that way direct conscious desire (toward escaping the pain exclusively) but that is not a switch.

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