Cathexis and catharsis: An integrated neuropsychoanalytic model of serotonergic action

The history of mental science is marked by a divide between the subjective, energetic models of psychoanalysis and the objective models of computational neuroscience. Reductionist approaches often fail to bridge this gap or adequately explain the structural complexity of psychopathology. This conceptual synthesis aims to propose a unified, testable neurocomputational framework anchored in the Free Energy Principle (FEP).

We conduct a theoretical synthesis mapping classical psychodynamic constructs onto the computational dynamics of Active Inference and neuromodulatory neurobiology. We formalize Freud's "Wish" as a high-precision allostatic prior, and drive as prediction error that compels the system to perform work. The Extended Reticular Thalamic Activating System (ERTAS) is analyzed as the physical operator of this economy.

Catharsis (discharge/primary process) is mapped as the efficient minimization of free energy via established habits, mediated by routing dopaminergic drive into the dorsal striatum and stabilized by 5-HT1A signaling. Cathexis (binding/secondary process) involves inhibiting immediate discharge for generative model revision, triggered by the lateral habenula and mediated by 5-HT2A signaling. Consolidation occurs via the Gs pathway. We detail a serotonergic "precision switch" acting as a meta-regulator of the Ego, arbitrating between stability, reactivity, and growth.

The mind-brain functions as a hierarchical generative model striving to minimize entropy. This integrated model reframes psychopathology (e.g., depression, mania, psychosis) as "computational pathologies" of precision weighting where the switch between binding and discharge becomes stuck. This provides a rational basis for precision psychiatry, integrating pharmacological modulation of gain control with psychotherapeutic restructuring.