Neuroimaging in Functional Neurological Disorder: State of the Field and Research Agenda, 2021, Perez, Carson, Edwards, Hallet, Stone et al

[Sean]

In the FND field, there is a clear expansionistic tendency to subsume more and more inside the FND category including headache, fatigue etc.

They want to append that diagnosis to literally every other diagnostic category. That is why the BPS club have been pushing the whole 'transdiagnostic' thing so hard, for years. It is one of Chalder's favourite themes, IIRC.

Yes, Mr Patient, you have terminal bowel cancer, and less than three months to live. But you also have a functional overlay that is just as important, and requires you to waste spend as your remaining time and energy on confronting and dealing with it, to our satisfaction. Because... reasons.​

I wish that was a joke.

There is extremely serious psychopathology going here alright. Just not in their patients.

yes, it's a known phenomenon--diagnostic creep. it's helpful to maximize the purported impact of your work.

More like diagnostic flood.

 

[SNT Gatchaman]

In relation to Walitt et al. this paper says —

Task neuroimaging in FND-movt has also identified an important role for the right temporoparietal junction (rTPJ) based network in self agency disturbances. For example, a within-group study comparing functional (involuntarily perceived) movements to volitional movements in a functional tremor cohort showed hypoactivation of the rTPJ. This study also identified reduced connectivity between primary sensorimotor regions and the rTPJ, suggesting impaired feed forward processing. Other studies across a variety of FND subtypes support roles for brain circuits implicated in motor conceptualization, inhibitory control, attention, predictive processing/perceptual inference, meta-cognition, belief/expectation, emotion control, and threat-related defense behaviors in the pathophysiology of FND

Referencing —

The involuntary nature of conversion disorder (2010, Neurology)

Pathogenesis and pathophysiology of functional psychogenic movement disorders (2019, Neurobiology of Disease)

Neural correlates of sense of agency in motor control: A neuroimaging meta-analysis (2020, PLOS ONE)

 

[Woolie]

I would love to know what "network dynamics" are.

Hi @Arnie Pye! You wrote this comment a year ago, but I just noticed you didn't get a reply.

"Network dynamics" is a pretty loose term, but it generally refers methods that try to measure the degree to which activity in two brain regions is "synchronised". One common method is to put people in the fMRI scanner, ask them to just lie there, and then look at the ebb and flow of brain activity as they lie there. So in the figure below, you see that some regions are "in synch". As activity in one of them rises, so does the other one. Other areas are in opposition - as activity in one rises, activity in the other goes down. You can use these data to build maps of the various "networks" in the brain.



The networks that you see when people are just lying in the scanner are pretty consistent across individuals.

So then you can look at whether there are differences between clinical groups in the degree of synchrony between two areas. You can just compare how much synchrony there is within known networks. Or alternatively, you can look at more complicated measures, like how rapidly people "switch" between different networks and how much total time they spend in each state.

Nobody really knows what it all means.

 

[Utsikt]

Nobody really knows what it all means.

Or if it has any relevance at all.