Further implications for a PTSD model?

[Syntheso]

With regards to David's proposed theory (which implicates thalamocortical networks and feedback loops), see;
 

 

Activation of Thalamo-Cortical Systems in Post-Traumatic Flashbacks: A Positron Emission Tomography Study

 

Abstract

Trauma victims with post-traumatic stress disorder (PTSD) often experience ‘flashbacks’ that are described as being different from memories of other fearful biographic situations. We used Positron Emission Tomography and Statistical Parametric Mapping to compare in the same subject brain activation patterns during induced flashbacks with recall of fearful non-traumatic situations. During fearful recall there were significant activations of right precuneus. When traumatic memories were compared to neutral, right lingual gyrus, right thalamus / mamillary bodies, and right cerebellum were significantly activated. When brain activation during flashbacks was compared to simple fear, right mediodorsal thalamus (MD), right precuneus, and right cerebellum were significantly more active. With respect to recent experimental evidence concerning the function of thalamo-cortical systems, we hypothesize that post-traumatic flashback experiences are based on hyperactive thalamo-cortical ‘closed loop’ networks.

 

This study suggests that decreasing cerebral blood flow in the thalamus of PTSD patients can reduce 're-experience' symptoms. Perhaps this has some relevance for us.

[BigPapaChakra]

Interesting you posted this because I was just looking into both (1) a SPECT Scan (blood flow to different brain regions), and (2) HEG Biofeedback (consciously controlling blood flow throughout the brain). Thanks! 

[Syntheso]

(1) a SPECT Scan (blood flow to different brain regions)

I have had a CT scan that apparently didn't show anything abnormal (wasn't actually done for HPPD though, but to rule out the shunt in my head and hydrocephalus as causes for HPPD symptomatology), I wonder if a SPECT scan would be more telling.

[BigPapaChakra]

I believe so. I had an MRI and (I believe) a CT scan that showed no structural abnormalities despite a history of concussions and cracking my head open (lol). Check this out: Brain SPECT Imaging in Complex Psychiatric Cases: An Evidence-Based, Underutilized Tool 

[miketusa]

One of the few times I went to the doctor bio feed back was recommended. That, and that I go back to school and get a job to "relieve my subconscious anxieties." Unfortunately her presumptuous attitude made me feel like she didn't know what she was talking about. Perhaps its worth checking out, though. 

[Syntheso]

I am skeptical that is is possible to reduce blood flow in certain parts of the brain as opposed to others. I wouldn't be interested in globally lowering the blood pressure in my head unless there was indication that it would be useful. I would be interested in exploring the idea of an op to lower the blood pressure in the thalamus.

[BigPapaChakra]

Well, I'm probably describing it wrong. It's teaching you to consciously up-regulate cerebral metabolism, particularly in the prefrontal cortex; altered cerebral metabolism takes place in almost every psychiatric illness, hence why the same medications don't work for everyone - they alter neuronal substrates without getting to the route causes of the problem, which can be altered cerebral metabolism, dysfunctional HPA-axis, etc. Hence why things like a SPECT Scan are so useful. 

 

Check this out. 

[Syntheso]

It does look very useful and worth investigating, but I feel it is a little off-topic as it is not specific to the thalamus (which is what links David's theory and the study cited above).

[onedayillsailagain]

http://link.springer.com/article/10.1023%2FA%3A1009571806136

 

 

Dissociation as a clinical psychiatric condition has been defined primarily in terms of the fragmentation and splitting of the mind, and perception of the self and the body. Its clinical manifestations include altered perceptions and behavior, including derealization, depersonalization, distortions of perception of time, space, and body, and conversion hysteria. Using examples of animal models, and the clinical features of the whiplash syndrome, we have developed a model of dissociation linked to the phenomenon of freeze/immobility. Also employing current concepts of the psychobiology of posttraumatic stress disorder (PTSD), we propose a model of PTSD linked to cyclical autonomic dysfunction, triggered and maintained by the laboratory model of kindling, and perpetuated by increasingly profound dorsal vagal tone and endorphinergic reward systems. These physiologic events in turn contribute to the clinical state of dissociation. The resulting autonomic dysregulation is presented as the substrate for a diverse group of chronic diseases of unknown origin.

[BigPapaChakra]

So that's stating increased vagal tone can perpetuate dissociation? If so, that's interesting, because Dr. Peat told me longgg ago (before my HPPD even got to the extent that it is now) that I should avoid doing anything that increases vagal tone with my history.

[onedayillsailagain]

Seems so. I don't know much about that to be honest, but I am very interested in the endophinergic mechanisms they observed. I'll see if I can get the full article one of these days.