From emotion processing to metacognition: mnemonic contributions in conversion/functional neurological symptoms

Functional neurological disorder (FND) is the term used (DSM-5) to refer to a disabling neuropsychiatric condition that is frequently encountered in medical practice, previously known as conversion disorder (CD) and described as Hysteria in the past century. It is characterised by neurological symptoms (e.g., weakness, numbness, tremor…) without evidence for any brain lesion. Early neurobiological accounts of this disorder were part of the foundation of psychiatry and neurology, but were then dominated by a purely psychodynamic perspective. The advent of neuroimaging in the last two decades has allowed a renewed interest in the “functional” brain underpinnings of these symptoms, with growing interest and increasing attempts to investigate them in a neuroscience perspective. In this brief review, I discuss recent evidence pointing to how top-down mechanisms may alter motor function in patients with motor FND/CD, through coupling with neural systems associated with internal self-monitoring, emotion regulation, and memory, and thus lead to the emergence of functional symptoms. More research however still needs to be undertaken to elucidate the causes (why they occur) of FND/CD, in addition to their neuro-anatomical substrates (how they occur).