Monday, October 15, 2018

Ongaro and Kaptchuk 2: Introduction

See Ongaro, Giulio, Kaptchuk, Ted J., 2018, Symptom perception, placebo effects, and the Bayesian brain. PAIN, Aug 6, 2018. (To read the full paper, click on "Article as pdf") This is all the introduction.

What I like about it (so far) and the predictive processing model for looking at the brain is that it treats the brain as a verb, not a noun.

First line of the introduction:

"The standard and ideal biomedical model of symptom perception treats the brain largely as a passive stimulus-driven organ."

Yup, that's the Cartesian way of looking at another human being.
Lest we forget, "being" is a verb. Or at least a gerund.

Second sentence:

"It embraces the notion that the brain absorbs sensory signals from the body and converts them, directly, into conscious experience."

It may do that before it has any experience to also draw on, e.g., within the first few months of life..

Third sentence:

"Accordingly, biomedicine operates under the assumption that symptoms are the direct consequences of physiological dysfunction and improvement is the direct consequence of the restoration of bodily function."

Yup, very convenient. Also useful. Has been successful to a large extent.
Also very Cartesian. Easy to blame the patient if their particular "pain" doesn't fit into the model, i.e., "the patient must be crazy"

Fourth sentence:

"Despite its success, the biomedical model has failed to provide an adequate account of 2 well-demonstrated phenomena in medicine: (1) the experience of symptoms without pathophysiological disruption, and (2) the experience of relief after the administration of placebo treatments."

Yup. E.g., (1) phantom limb pain, and (2) resolving it by stabbing a screwdriver into the artificial limb (one of the stories in Painful Yarns by Lorimer Moseley).

Fifth sentence:

"This topical review advances the idea that “predictive processing,” a Bayesian approach to perception that is rapidly taking hold in neuroscience, significantly helps accommodating these 2 phenomena."

At last!!

Sixth sentence:

"It expands on recent high-quality empirical work on predictive processing (1,7,19,24) and outlines, more broadly, how Bayesian models offer an altogether different picture of how the brain perceives symptoms and relief."

Ah yes... inevitably, there is always going to be a ton of side reading to do. Not that I mind side reading when motivated! I see we will have to go to blogposts 2.1 - 2.4.

7. Büchel C, Geuter S, Sprenger C, Eippert F. Placebo analgesia: a predictive coding perspective. Neuron 2014;81:1223–39.
19. Grahl A, Onat S, Büchel C.The periaqueductal gray and Bayesian integration in placebo analgesia. Elife 2018;7:e32930.
24. Kaptchuk TJ. Open-label placebos: reflections on a research agenda. Perspect Biol Med 2018;61:311–34.

.......................... Other blogposts in this series

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