K-hole

The K-hole refers to an extreme dissociative state induced by NMDA receptor antagonists at high doses (ketamine, 2-FDCK, methoxetamine, PCP). The plate describes it as a mechanism for replacing perceived reality: consciousness remains immersed, but within alternative phenomenological spaces, sometimes sustained with the eyes open. Its signature is the substitution of ordinary reality by internally generated content.

Neurochemical action

The plate locates the origin of the phenomenon in NMDA antagonism. The substance blocks the NMDA receptor, normally involved in coupling predictions with sensory input (thalamic relays). As the infusion or dose increases, the share of ascending sensory information (bottom-up) reaching the internal models decreases. The error-correction signal is cut off: the internal models become autonomous, meaning they keep running without being recalibrated by the outside world.

Bayesian predictive loop

The central explanatory framework is predictive coding. Under normal operation, the brain continually confronts its predictions (top-down) with sensory input (bottom-up), and the estimate (the inference) results from this ongoing update. Under NMDA blockade, updating is interrupted: prediction error is no longer taken into account. The brain stops correcting its models and freezes its estimate, which now depends only on internal predictions, until it no longer anchors in the physical environment.

Functional consequences

The plate details several effects stemming from this rupture of coupling:

• erasure of the perceived world: distortion, fragmentation, non-physical spaces, impossible geometries, or reality bracketed off.
• loss or dissolution of identity and of the body (disembodiment).
• vast mental spaces, sometimes more vivid than ordinary reality.
• non-linear time, suspended, dilated, or recomposed.
• loss of the narrative thread and fragmentation of the self.
• absence of any anchoring in the present and in the physical environment.

Dissociative mechanisms: the shift toward an alternative attractor

The sheet breaks the slide down into several stages. The disconnection of real input means sensory signals no longer reach, or barely reach, the internal models. The interruption of updating freezes the internal models. The internal generator then takes over: the brain is no longer constrained by external reality and generates a world from its models alone. There follows a saturation with endogenous content (scenes, forms, entities), then a stabilization into an attractor: the system settles into a stable, coherent, autonomous state, from which the alternative phenomenological experience emerges. The immersive interface can persist with the eyes open.

Typical experiences

The plate cites commonly reported content: architectural spaces, vast geometries; encounters with presences or entities; the sensation of being elsewhere, in another place or another reality; fusion with space, dissolution of boundaries.

Neuroscientific data and debates

On the side of correlates, the sheet mentions: reduced thalamus-centered connectivity, hyperpolarisation of pyramidal neurons (prefrontal cortex), global desynchronization of cortical coherences, decreased metabolism of cerebral blood flow, and dissolution of the default mode network (DMN) boundaries. The overall result is described as a progressive degradation of reality, yet one in which the shift toward an alternative dynamic remains subjectively coherent. The plate notes the dependence on dose and route of administration, as well as the rapidity of the return to baseline. It stresses tolerance (dose escalation, risk of dependence with repeated use) and precautions, without offering medical advice.

Sources

• Karl Friston, predictive coding and the free energy principle.
• Work on ketamine as an NMDA antagonist and pharmacological model of dissociation and psychosis.
• Imaging studies on ketamine effects (thalamo-cortical connectivity, brain rhythms, default mode network).
• Literature on dissociative phenomenology and disembodiment under dissociative anesthetics.