At sufficiently high doses of the drug ketamine

Ketamine

Ketamine is a drug used in human and veterinary medicine. Its hydrochloride salt is sold as Ketanest, Ketaset, and Ketalar. Pharmacologically, ketamine is classified as an NMDA receptor antagonist...

 (often 0.25 gram (0.00881849052627799 oz) to 0.5 gram (0.017636981052556 oz) or more), it is common to experience a "K-hole". This is a slang term for a subjective state of dissociation

Dissociation

Dissociation is an altered state of consciousness characterized by partial or complete disruption of the normal integration of a person’s normal conscious or psychological functioning. Dissociation is most commonly experienced as a subjective perception of one's consciousness being detached from...

 from the body which may mimic the phenomenology of schizophrenia

Schizophrenia

Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...

, out of body experiences or near death experience

Near death experience

A near-death experience refers to a broad range of personal experiences associated with impending death, encompassing multiple possible sensations including detachment from the body; feelings of levitation; extreme fear; total serenity, security, or warmth; the experience of absolute dissolution;...

s, and is often accompanied by feelings of extreme derealization

Derealization

Derealization is an alteration in the perception or experience of the external world so that it seems unreal. Other symptoms include feeling as though one's environment is lacking in spontaneity, emotional coloring and depth. It is a dissociative symptom of many conditions, such as psychiatric and...

, depersonalization

Depersonalization

Depersonalization is an anomaly of the mechanism by which an individual has self-awareness. It is a feeling of watching oneself act, while having no control over a situation. Sufferers feel they have changed, and the world has become less real, vague, dreamlike, or lacking in significance...

 and disorientation, as well as temporary memory loss

Memory loss

Memory loss can be partial or total and it is normal when it comes with aging. Sudden memory loss is usually a result of brain trauma and it may be permanent or temporary. When it is caused by medical conditions such as Alzheimers, the memory loss is gradual and tends to be permanent.Brain trauma...

 and vivid hallucination

Hallucination

A hallucination, in the broadest sense of the word, is a perception in the absence of a stimulus. In a stricter sense, hallucinations are defined as perceptions in a conscious and awake state in the absence of external stimuli which have qualities of real perception, in that they are vivid,...

s.

Ketamine and its subjective effects were related by Timothy Leary

Timothy Leary

Timothy Francis Leary was an American psychologist and writer, known for his advocacy of psychedelic drugs. During a time when drugs like LSD and psilocybin were legal, Leary conducted experiments at Harvard University under the Harvard Psilocybin Project, resulting in the Concord Prison...

 to the eighth and final circuit of his eight-circuit model of consciousness, along with DMT

Dimethyltryptamine

N,N-Dimethyltryptamine is a naturally occurring psychedelic compound of the tryptamine family. DMT is found in several plants, and also in trace amounts in humans and other mammals, where it is originally derived from the essential amino acid tryptophan, and ultimately produced by the enzyme INMT...

 and high doses of LSD. Impressions of a K-hole may also be similar to experiences brought on by ingesting Salvia divinorum

Salvia divinorum

Salvia divinorum is a psychoactive plant which can induce dissociative effects and is a potent producer of "visions" and other hallucinatory experiences...

, which like Ketamine is also an atypical psychedelic

Psychedelic drug

A psychedelic substance is a psychoactive drug whose primary action is to alter cognition and perception. Psychedelics are part of a wider class of psychoactive drugs known as hallucinogens, a class that also includes related substances such as dissociatives and deliriants...

 exhibiting dissociative

Dissociative drug

Dissociatives are a class of psychoactive drugs which are said to reduce or block signals to the conscious mind from other parts of the brain...

 properties.

Description

Experience of the K-hole is, like many psychedelic experience

Psychedelic experience

The term "psychedelic experience" is vague – characterized by polyvalence or ambiguity due to its nature – however in modern psychopharmacological science as well as philosophical, psychological, neurological, spiritual-religious and most other ideological discourses it is understood as an altered...

s, highly subjective, and Ketamine's effects may vary greatly between individuals. Often set and setting

Set and setting

Set and setting describes the context for psychoactive and particularly psychedelic drug experiences: one's mindset and the setting in which the user has the experience. This is especially relevant for psychedelic or hallucinogenic experiences...

, the use of other drugs

Poly drug use

Polydrug use refers to the use of two or more psychoactive drugs in combination to achieve a particular effect. In many cases one drug is used as a base or primary drug, with additional drugs to leaven or compensate for the side effects of the primary drug and make the experience more enjoyable...

 (prescribed

Prescription drug

A prescription medication is a licensed medicine that is regulated by legislation to require a medical prescription before it can be obtained. The term is used to distinguish it from over-the-counter drugs which can be obtained without a prescription...

 or otherwise), as well as the user's physiology

Physiology

Physiology is the science of the function of living systems. This includes how organisms, organ systems, organs, cells, and bio-molecules carry out the chemical or physical functions that exist in a living system. The highest honor awarded in physiology is the Nobel Prize in Physiology or...

, psychology

Psychology

Psychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...

, personality

Personality psychology

Personality psychology is a branch of psychology that studies personality and individual differences. Its areas of focus include:* Constructing a coherent picture of the individual and his or her major psychological processes...

 and brain chemistry are among many defining factors which may affect an individual's personal experience of a K-hole, as well as other altered states of consciousness

Altered state of consciousness

An altered state of consciousness , also named altered state of mind, is any condition which is significantly different from a normal waking beta wave state. The expression was used as early as 1966 by Arnold M. Ludwig and brought into common usage from 1969 by Charles Tart: it describes induced...

 in general.

An individual's impression of a K-hole may include distortions in bodily awareness, such as the feeling that one's body is being tugged or is gliding on silk, flying, or has grown very large or distended. Users have reported the sensation of their soul leaving their human body. Users have also often reported feeling more skeletal or becoming more aware of their bones - the shape of their hands is also often of interest. Users may experience worlds or dimensions that are ineffable, all the while being completely unaware of or have lost their individual identities or their sense of an extant and external world. Users have reported intense hallucinations including visual hallucinations, perceptions of falling, fast and gradual movement and flying, 'seeing God', entity contact, feeling connected to other users, objects and the cosmos, experiencing psychic connections, and shared hallucinations and thoughts with adjacent users.

Users may feel as though their perceptions are located so deep inside the mind that the real world seems distant (hence the use of a "hole" to describe the experience). Some users may not remember this part of the experience after regaining consciousness, in the same way that a person may forget a dream. Owing to the role of the NMDA receptor

NMDA receptor

The NMDA receptor , a glutamate receptor, is the predominant molecular device for controlling synaptic plasticity and memory function....

 in long-term potentiation

Long-term potentiation

In neuroscience, long-term potentiation is a long-lasting enhancement in signal transmission between two neurons that results from stimulating them synchronously. It is one of several phenomena underlying synaptic plasticity, the ability of chemical synapses to change their strength...

, this may be due to disturbances in memory formation

Encoding (Memory)

Memory has the ability to encode, store and recall information. Memories give an organism the capability to learn and adapt from previous experiences as well as build relationships. Encoding allows the perceived item of use or interest to be converted into a construct that can be stored within the...

. The "re-integration" process is slow, and the user gradually becomes aware of surroundings. At first, users may not remember their own names, forget they are human, or even know what that means. Movement is extremely difficult, and a user may not be aware that he or she has a body at all, so being able to sit and talk is rare.