Nervous System Mastery: Metaphors, mechanisms and prediction errors
This month I want to acknowledge the delicate balancing act between metaphor and mechanism. The scientific study of living beings, especially human beings often starts with the former and regardless as to whether the scientific mechanism is found or not we need a metaphor to make it land in the real world.
A storage or prediction issue
Let’s explore an example. The pioneering trauma work led by Bessell van der Kolk has been a blessing for so many people, me included. His 2014 book The Body Keeps the Score has been a best seller for many years and is published in over 30 other languages. For me the book gave a voice to those who knew and felt we had to move away from one dimensional reductionist frameworks and surface level cognition, especially in relation to physical and psychological trauma. So the body keeps score metaphor implies that experience is literally held in the flesh. As a complex trauma survivor I wholeheartedly can relate to this. I have also lost count on a personal and professional level how many times people have found refuge in this book. However, it is also worth highlighting that many cultures have expressed these interconnected, multidimensional beliefs, from the get go, long before The Body Keeps the Score was published.
po-tay-to, po-tah-to
Now the advances in neuroscience and computational modelling suggest that it is not actually the body keeping score. But rather the brain is suffering from a loss of metastability -simply put the brain can’t switch ‘networks’ with ease, it is stuck in enduring danger mode. Trauma injures the nervous system, it is not a storage issue but prediction issue. In computational terms the trauma causes prediction errors (based on previous experience) that ultimately the threat remains, evidenced in numerous ways -such as hypervigilance, dissociation, visual, bodily, flashbacks, avoidance and so on.
Again all this language makes perfect sense. But in essence we have just replaced one metaphor with another. We still don’t understand the mechanism but we are perhaps closer. Although a lack of metastability shows itself in other guises, for example people with doctrinaire views and those found on the political extremes display more cognitive rigidity. Many humans cannot switch networks with fluidity for a whole host of reasons.
Take care with the intellectual lineage
The trillions of connections and networks creating our individualised reality is breathtaking. So much is happening under the surface. The departure away from the stimulus-response models that implied our nervous systems were passive, surface level receivers of information is fantastic. And of course many scientists and philosophers had proposed that the brain was a dynamic, active hypothesis testing organ long before neuroscience was fully established. It makes perfect sense -we don’t consciously choose our response in a crisis -faffing around thinking about it we would be dead. Or (another example with Wimbledon round the corner) - a professional tennis player doesn’t wait until they see the ball to process and plan the response. We are clearly utilising inference, prediction.
But. We have to take care with the current dominant brain hypothesis framework, led by the mathematically refined Bayesian model, utilising perception, prediction and correction. There are many challenges and concerns about the framework ranging from lacking consistent empirical support and biological implausity including the energy costs.
However, regardless of the metaphor or even the mechanism, we have to keep advancing our research and understanding. Also irrespective of the academic outcomes we appear to heal our nervous system injuries best (establishing or reestablishing metastability) by utilising, time, hope, nature, community, trust, understanding & purpose.