Plato's cave and the neurobiology of reality construction.

Perception is increasingly framed, across neuroscience and theoretical psychology, as an active inferential process rather than a passive transcription of the external world. Contemporary models suggest that sensory experience emerges from internally generated hypotheses constrained by prediction, uncertainty, and the statistical structure of the environment. Long before these developments, Plato's allegory of the cave offered a striking intuition: human beings may take mediated appearances for reality, while remaining largely unaware of the mechanisms that produce what is seen and believed. This Perspective revisits the cave allegory as a conceptual scaffold for a clinically relevant idea: that medicine, particularly at the interface of neurology and psychiatry, benefits from a more explicit and operational understanding of how the brain constructs subjective reality. In dialogue with predictive processing, hierarchical inference, and computational accounts of psychosis and hallucinations, the paper argues that symptoms such as hallucinations can be re-described as alterations in reality construction rather than isolated "perceptual errors". Such reframing does not compete with existing diagnostic frameworks; it complements them by foregrounding a dimension that is often implicit in clinical practice: the brain's generative role in perception. By placing Plato's anticipatory metaphor alongside modern neurocognitive models, this Perspective proposes that clarifying "how reality is built" can enrich clinical reasoning, improve explanatory dialogue with patients, and open concrete research directions linking subcortical gating, cortical priors, and symptom phenomenology. The cave thus becomes not an ornament of erudition, but an early diagram of a problem that remains central to contemporary neuropsychiatry.