Excitatory and inhibitory conversive experiences: neurobiological features involving positive and negative conversion symptoms.

Abstract

Previous reviews have focused on neurobiological and physiological mechanisms underlying conversion disorder, but they do not usually distinguish between negative and positive conversion symptoms. Some authors have proposed that different phenomena should underlie both situations and that diverse emotion regulation strategies (under- vs. overregulation of affect) should be related to different internal experiences (excitatory experiences with hyperarousal manifestations vs. inhibitory experiences coexisting with hypoarousal states, respectively). After a careful review of the literature, we conclude that there is not a unique theory comprising all findings. Nevertheless, we have also collected some replicated findings that should be salient. Patients manifesting positive conversion symptoms tended to present with limbic hyperfunction, not sufficiently counteracted by prefrontal control. This leads to underregulation of affect mechanisms, increased emotional reactivity and autonomic hyperarousal. The opposite pattern (with a prefrontal overfunction working as a cognitive brake over the limbic system) has been described during negative conversion manifestations. We also highlight the influence of fronto-limbic circuits over cortico-striato-thalamo-cortical circuits' regulation, whose horizontal and vertical synchronization has been at the spotlight of the genesis of conversion and dissociative disorders.