Neuroscience

Mouse study examines the underpinnings of hallucinations

Hallucinations result in dramatic disruptions in perception and cognition, but the changes in brain activity that underlie such alterations are not well understood. In a study publishing March 26 in the journal Cell Reports, ...

Neuroscience

Listening to the inner voice

(Medical Xpress)—Perhaps the most controversial book ever written in the field of psychology, was Julian Janes' mid-seventies classic, "The Origin of Consciousness in the Breakdown of the Bicameral Mind." In it, Jaynes ...

Medical research

Discovery suggests route to safer pain medications

Strategies to treat pain without triggering dangerous side effects such as euphoria and addiction have proven elusive. For decades, scientists have attempted to develop drugs that selectively activate one type of opioid receptor ...

Psychology & Psychiatry

Psychotic symptoms in children may have a genetic cause

A 6-year-old boy began hearing voices coming from the walls and the school intercom telling him to hurt himself and others. He saw ghosts, aliens in trees, and colored footprints. Joseph Gonzalez-Heydrich, MD, a psychiatrist ...

Health informatics

Biologists train AI to generate medicines and vaccines

Scientists have developed artificial intelligence software that can create proteins that may be useful as vaccines, cancer treatments, or even tools for pulling carbon pollution out of the air.

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Hallucination

A hallucination, in the broadest sense, 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, substantial, and located in external objective space. The latter definition distinguishes hallucinations from the related phenomena of dreaming, which does not involve wakefulness; illusion, which involves distorted or misinterpreted real perception; imagery, which does not mimic real perception and is under voluntary control; and pseudohallucination, which does not mimic real perception, but is not under voluntary control. Hallucinations also differ from "delusional perceptions", in which a correctly sensed and interpreted genuine perception is given some additional (and typically bizarre) significance.

Hallucinations can occur in any sensory modality — visual, auditory, olfactory, gustatory, tactile, proprioceptive, equilibrioceptive, nociceptive, and thermoceptive.

A mild form of hallucination is known as a disturbance, and can occur in any of the senses above. These may be things like seeing movement in peripheral vision, or hearing faint noises and voices.

Hypnagogic hallucinations and hypnopompic hallucinations are considered normal phenomena. Hypnagogic hallucinations can occur as one is falling asleep and hypnopompic hallucinations occur when one is waking up.

Hallucinations can also be associated with drug or alcohol use (particularly deliriants), sleep deprivation, psychosis, neurological disorders, and delirium tremens.

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