FND neural mechanisms
The scheme is adapted from Hallet et al., (2023) and primarily refers to functional motor disorder, but basically any form of functional neurological disorder can be explained using its guidelines.
After planning the movements in the SMA, they are generated by the motor cortex. This triggers information signals that are compared with the feedback interoceptive and exteroceptive signals resulting from the movement. If the signals do not match, there will be a feeling that the movement is 'involuntary'.
The brain has a model of the body and the world that it uses to predict reality. If the feedback signals do not match the prediction, a prediction error is generated, which adjusts the model so that the next time the prediction matches the feedback. In patients with FND , it is assumed that the prediction error is not updated, perpetuating symptoms and dysfunction.
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Cretton, A., Brown, R. J., LaFrance Jr, W. C., and Aybek, S. (2020). What does neuroscience tell us about the conversion model of functional neurological disorders?. The Journal of neuropsychiatry and clinical neurosciences, 32(1), 24-32.
Hallett, M., Aybek, S., Dworetzky, B. A., McWhirter, L., Staab, J. P., and Stone, J. (2022). Functional neurological disorder: new subtypes and shared mechanisms. The Lancet Neurology, 21(6), 537-550.
Roelofs, J. J., Teodoro, T., and Edwards, M. J. (2019). Neuroimaging in functional movement disorders. Current neurology and neuroscience reports, 19, 1-7.