Magic and Reality I

[Barrett Dorko]

This is inspired by Richard Dawkins’ The Magic of Reality. Quoted passages are from there.

In order to grasp the reality of something we use our senses. If they need extension we employ machinery – thus we can see and measure both bacteria and nebulae beyond the stars we can't see with the naked eye.

There is a third way in which reality can be described and consequently tested – the model. Often a movie or TV show will depict a figure building a model. They always appear precise, engrossed, focused and alone. I've always liked that for some reason.

Models test our imagination. They suggest what might be going on. Though not as simple as a just-so story, they can lead us toward experiments that challenge them, predict what will happen and draw conclusions based upon the best available evidence. To me, they resemble science-based thinking more so than evidence-based practice.

We look to see if our predictions are right or wrong. If they are right, this increases our confidence that the model really does represent reality.

In ’99 Melzack presented us with a model and we talk about it often (links and pictures welcomed). This series of posts is about understanding it, simplifying it, using it and speaking about it in a way others can understand.

More soon.

[Barrett Dorko]

I see Carol Lynn has posted this on her Facebook wall and I appreciate that.

I'd love to see Melzack's model shown here. I haven't the computer chops to do it yet.

[Barrett Dorko]

Seth Will has linked a paper about models from 1945 to my Facebook post.

It looks good and I'll read it carefully tonight.

[Diane]

Originally Posted by Barrett Dorko

I see Carol Lynn has posted this on her Facebook wall and I appreciate that.

I'd love to see Melzack's model shown here. I haven't the computer chops to do it yet.

[Barrett Dorko]

Thanks Diane. One of these days I'm going to figure out this computer thing.

Future posts will refer to this picture. I'm interested to see how many downloads we can get.

I'm also interested in who downloads it. Think 1984. Or, better yet, Lord of the Flies (lots of little brothers).

But no pressure.

[Alice Sanvito]

Maybe this is a good place to ask: what is "tonic" and "phasic"?

[Diane]

Tonic means "continuous" (i.e., no breaks: "implies lack of interruption: The horizon is a continuous line.")

Phasic means "continual" (i.e., ongoing, but in a punctuated manner: "Continual is chiefly restricted to what is intermittent or repeated at intervals")

[byronselorme]

Originally Posted by Alice Sanvito

Maybe this is a good place to ask: what is "tonic" and "phasic"?

I was going to ask the exact same question

[byronselorme]

Originally Posted by Diane

Tonic means "continuous" (i.e., no breaks: "implies lack of interruption: The horizon is a continuous line.")

Phasic means "continual" (i.e., ongoing, but in a punctuated manner: "Continual is chiefly restricted to what is intermittent or repeated at intervals")

Hi Diane, from the dictionary link you gave I get confused.

con·tin·u·al(kn-tny-l)
adj. 1. Recurring regularly or frequently: the continual need to pay the mortgage.
2. Not interrupted; steady: continual noise; a continual diet of vegetables.

con·tin·u·ous(kn-tny-s) adj. 1. Uninterrupted in time, sequence, substance, or extent. See Synonyms at continual.
2. Attached together in repeated units: a continuous form fed into a printer.
3. Mathematics Of or relating to a line or curve that extends without a break or irregularity.

phase(fz) n. 1. A distinct stage of development: "The American occupation of Japan fell into three successive phases" (Edwin O. Reischauer).
2. A temporary manner, attitude, or pattern of behavior: just a passing phase.
3. An aspect; a part: every phase of the operation.

I couldn't find an explanation for Tonic that made any sense on the dictionary. It was a little hard to understand the difference between the two but am I right to say that Tonic would continue on indefinitely while Phasic would mean that it is constant but has a fluctuating constant quality, perhaps like a sine wave?

[Diane]

Gee, I thought that was clear...

OK. How about this:
tonic = a steady light source, like from the sun.
phasic = a strobe light.

[byronselorme]

Sorry. Got confused because continual had some similar definitions to continuous.

Was my rewording wrong then?

Sorry to get stuck in small things. It is such an important model I don't want to make sense of something and build on it, only to find I hadn't correctly understood.

The Neuromatrix model doesn't have too many words in it. I kind of expect they are packed solid with meaning. Which I am still not really good at understanding. I only understand that it is important but not why. Is there an explanation on Soma?

[Jon Newman]

Part of the image that doesn't help my understanding is how "anxiety" and "depression" are labeled as an "input from brain".

I can begin to get it by thinking of, for example, the thalamus. The thalamus is part of the brain, it is brain, but it is not the whole brain. Neural activity impinging on the thalamus would be input to the thalamus from the non-thalamus parts of the brain. And neural activity from the thalamus would be output from the thalamus to non-thalamus parts of the brain.

Using the analogy above and a substitution strategy for the model under consideration, anxiety and depression are considered to be outputs of non-body-self neuromatrix to the body-self neuromatrix. But I find that incoherent.

[Diane]

Continual and continuous are always confused, another one of those confusions, like they're, there, and their, or lose and loose, that I find a bit .. depressing. Maybe because the differences were so drilled into me.

Anyway, "tonic" and "phasic" have to be understood in order to understand neuroscience. Might as well use examples from neuroscience:

1. "inhibition can be "phasic" or "tonic". Phasic inhibition is a short-lasting inhibition typically generated by the activation of GABAA receptors following action potentials in a presynaptic interneuron." LINK

2. "..however, I believe that the insertion of the term "transient" was not done in the most effective manner; I believe the authors should keep "phasic" in the part of the sentence "Phasic activation of DA neurons..." since that is the term used to denote burst firing by those studying this phenomenon in both rodents and primates" LINK

3. "These sustained changes in activity are sometimes referred to as ‘phasic’ and ‘tonic’ modes (for sustained low and high firing rates, respectively), thought to correspond to different levels of coupling between the cells and different cognitive states." LINK

4. Many more examples. LINK

Another way to learn the difference would be to ask a musician. They work with intervals all the time. A note is either sustained (tonic, like when you push on that special "sustain" foot pedal on a piano, and notated by a open circle as I recall) or repeated (phasic), plunked numerous times in the space of a 'beat').

(I think. I'm not a musician, so...hey Caro - what does tonic and phasic mean in terms of music?)

[Diane]

Originally Posted by Jon Newman

Part of the image that doesn't help my understanding is how "anxiety" and "depression" are labeled as an "input from brain".

I can begin to get it by thinking of, for example, the thalamus. The thalamus is part of the brain, it is brain, but it is not the whole brain. Neural activity impinging on the thalamus would be input to the thalamus from the non-thalamus parts of the brain. And neural activity from the thalamus would be output from the thalamus to non-thalamus parts of the brain.

Using the analogy above and a substitution strategy for the model under consideration, anxiety and depression are considered to be outputs of non-body-self neuromatrix to the body-self neuromatrix. But I find that incoherent.

Yup. Every part of the brain has a perspective. Each part has afferent and efferent. Each part receives input and projects outward. It's a community in there, not a monolith.

[Jon Newman]

That's true but...

The neuromatrix, as Melzack conceived of it, produces a continuous message that represents the whole body in which details are differentiated within the whole as inputs come into it. We start from the top, with the experience of a unity of the body, and look for dif- ferentiation of detail within the whole. The neuromatrix, then, is a template of the whole, which provides the characteristic neural pattern for the whole body (the body’s neurosignature) as well as subsets of signature patterns (from neuromodules) that relate to events at (or in) different parts of the body. see Pain in the 21st Century: The Neuromatrix and Beyond, p. 136

It seems to me, given the above, that depression and anxiety should be classified as outputs of the body-self neuromatrix, not inputs to it.