SEARCH · PubMed Health

Results for “Hallucinations”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources

PubMed1976

Human EEG spectra before and during cannabis hallucinations.

EEG correlates of subjective experiences induced by delta9-trans-tetrahydrocannabinol (THC) and EEG correlates of individual disposition to such experiences were investigated. Twelve normal volunteers took 200 mug/kg THC orally. The subjects were asked to signal subjective experiences. The EEG was analyzed (period analysis) before and repeatedly after THC injestion, during resting, attention, eye closure, visual hallucinations, and body image disturbances. EEG frequency spectra differed significantly between resting and visual hallucinations and body image disturbances. The differences included slower alpha and more theta during THC experiences, reminiscent of initial drowsiness EEG, and of some results in schizophrenia. The differences between spectra during visual hallucinations and during body image disturbances indicate different functional brain states. Subjects with a high tendency to cannabinol induced experiences exhibited resting spectra before and after THC with higher modal alpha frequences (reminiscent of subjects with high neuroticism scores) than subjects with a low tendency.

Adult↗

PubMed1977

"Release hallucinations" as the major symptom of posterior cerebral artery occlusion: a report of 2 cases.

Visual hallucinations were the presenting symptoms in 2 patients with probable infarcts in the territory of a posterior cerebral artery. They occurred in areas of paracentral scotomas, right in Patient 1 and left in Patient 2. In Patient 1 they were formed, prolonged, and not apparently related to past experience. In Patient 2 they were at first paroxysmal and unformed, with more prolonged metamorphopsia; later there appeared to be palinoptic formed images, possibly postictal in nature. Such hallucinations appear to be of a "release" type, and may be more common than is generally appreciated in patients with posterior cerebral artery occlusion.

Adult↗

PubMed1979

Musical hallucinations in a deaf elderly patient.

A remarkably observant 89-year-old woman experienced the abrupt onset of musical hallucinations on the background of longstanding progressive hearing loss and in the absence of psychosis or major dementia. These hallucinations were nearly constant, wellformed perceptions of religious hymns, and their content could be altered by several mechanisms. The patient also occasionally heard voices recapitulating childhood experiences. One can speculate that the syndrome relates to sensory deprivation.

Aged↗

PubMed1977

Naloxone-induced reversal of schizophrenic hallucinations.

In a single-blind pilot study 0.4 mg naloxone i.v. was found temporarily to reduce or abolish auditory hallucinations in four cases of chronic schizophrenia whereas saline was without effect. In one of these patients there was a similar reversal also of her visual hallucinations. Two additional cases who denied hearing voices before the injections, reported no subjective effects.

Adult↗

PubMed1977

Verbal auditory hallucinations: mind, self, and society.

Verbal auditory hallucinations of schizophrenic patients are usually sensed as coming from m-ltiple voices. The voices are usually not recognized by patients; they are anonymous. They are expressed mainly in the second person (as if directed to the patient by others), occasionally in the third person (as if two or more persons are overheard talking about the patient), very rarely in the first person. They are sensed as separate from the self and out of the patient's control. All of these characteristics can be said to describe how a person generalizes from his social experiences a societal evaluation of himself. In addition, the voices of schizophrenic patients are predominantly disparaging, call approbrious names, or are accusatory. Schizophrenics tend to come from and be of low socioeconomic status. The hallucinations appear to be related to the schizophrenic's sense of society's disparagement of him because of his low socioeconomic status and achievement.

Adult↗

PubMed1976

Recurrent hallucinations following ketamine.

Recurrent hallucinations appeared in an 11-year-old boy during 5 days following ketamine anaesthesia. Previous anaesthesia with ketamine and adequate diazepam supplementation did not produce any such effect. The phenomenon of delayed recurring hallucinations is a rare but dangerous side-effect of ketamine, not unlike LSD flashbacks. The described case lends support to previous reports on the value of diazepam in the prevention of post-ketamine perceptual abnormalities.

Anesthesia, General↗

PubMed1975

[Hallucinations and experience of fear].

Hallucinations, which are experienced in fear-evoking situations of helplessness and (external) danger, are attempts of defence and the realisation of elementary needs of self-preservation and security. The reality-denying self-deception is accompanied by the mobilisation of own protective potencies. Hallucinations are experienced fearfully, so that there is a situation of helplessness and danger. They are--as neurotic symptoms--an attempt to realise libidinous and/or aggressive desires with the manifestation of (condemning and punishing) defence in the projective perception. The self-deception here concerns the denial of own internal conflicts.

Defense Mechanisms↗

PubMed1975

Muscial hallucinations in deafness.

Formed auditory hallucinations associated with acquired deafness have seldom been reported in the English literature. In the past year we have had the unusual opportunity of examining two deaf patients whose complaint when first seen was that of hearing music.

Age Factors↗

PubMed1978

Paranoid delusions and auditory hallucinations associated with digoxin intoxication.

The 83-year-old woman in this case report developed paranoid delusions and auditory hallucinations in association with toxic serum levels of digoxin, while remaining alert, unagitated, and coherent in thinking. No cardiovascular or metabolic abnormalities were discovered to account for her psychiatric symptoms. Her mental status rapidly returned to normal as serum digoxin declined to therapeutic levels.

Aged↗

PubMed1979

The elicitation of visual hallucinations via brief instructions in a normal sample.

College students tested in groups were given brief suggestions either to "see" or to "imagine" a kitten. Subjects responded twice, once with eyes open and once with eyes closed. They rated the duration, transparency, and vividness of their imagery, and also their involvement in and belief in the reality of their imaginings under both eye closure conditions. "Imagine" suggestions elicited imagery of longer duration than "see" suggestions. Although subjects reported longer, more vivid, and less transparent imagery with their eyes closed, this effect was dependent on the order of eye closure (i.e., whether the eyes closed instruction preceded or followed the eyes open instruction). The three dimensions of imagery intercorrelated, and each dimension also correlated with subjects' degree of involvement in and belief in their imaginings. A minority of subjects given both the "see" and "imagine" suggestions reported believing that their imaginings were real events during the suggestion period. Furthermore, belief in imaginings was the only variable that correlated with hypnotic susceptibility. These data indicate that hallucinations (i.e., believed-in imaginings) can be elicited from a minority of "norman" subjects with brief instructions.

Female↗

PubMed1975

Visual hallucinations and delirium during treatment with amantadine (Symmetrel).

In 13 elderly patients, 12 of whom had Parkinson's disease, visual hallucinations and delirium developed as a side effect of amantadine hydrochloride (Symmetrel) therapy. The symptoms promptly disappearred when amantadine was discontinued. Thereafter, each parkinsonian patient was treated satisfactorily with levo-dopa. Treatment with a combination of amantadine and an anticholinergic agent increases the likelihood of delirium because of the hazard of retention of urine. Although amantadine is effective in the treatment of Parkinson's disease in the elderly, the incidence of delirium as a complication seems higher in this age group.

Aged↗

PubMedDate not supplied

Awareness, dreams, and hallucinations associated with general anesthesia.

This incidence of mental aberrations (awareness, dreams, and hallucinations) in 490 adult patients undergoing a variety of surgical procedures was investigated. The total incidence of mental aberrations reported was 11 percent (awareness 1 percent, halluncinations 2 percent, dreams 8 percent). No statistically significant correlation was found between the incidence of unusual mental reactions and the anesthetic agents employed, the age or sex of the patients, or the duration or type of surgical prcedure.

Adolescent↗

PubMed1975

Transformations of consciousness. A cartography. I. The perception-hallucination continuum.

Self-awareness emerges from the evolutionary transformation of material structures into magical, mythical and mental structures of consciousness. Western varieties of conscious states may be mapped on a perception-hallucination continuum of increasing ergotropic or hyper-arousal. These levels of subcortical arousal are cortically or cognitively interpreted as normal, creative, hyperhrenic, cataleptic and ecstatic states. During increasing hyper-arousal (characterized by EEG desynchronization): (1) the variability of the EEG amplitude decreases in introverts whereas in extroverts, it increases; (2) exteroception is transformed into an experience of interoception, while willed motor activity becomes increasingly impaired and ultimately inhibited, and (3) information processing during these hallucinatory states is preferentially shifted from the speech dominant and motor-coordinating or "major" toward the nonverbal, gestalt-perceiving, the non-dominant or "minor" cortical hemisphere.

Amnesia↗

PubMed1992

Visual hallucinations on eye closure after cardiovascular surgery.

Visual hallucinations on eye closure are very uncommon. The underlying mechanism remains controversial. We report on a new case after carotid endarterectomy and coronary artery bypass graft surgery. The hypothesis of a temporal lobe epilepsy is discussed.

Carotid Artery, External↗

PubMed1979

[Induced visual hallucinations and visual adaptation disorders in patients with delirium tremens].

In 91 cases of alcoholic delirium, acute alcoholic hallucinosis and alcoholic withdrawal conditions, a clinico-experimental study of the formation of evoked visual hallucinations was conducted with the aid of a dozed compression of the eye (a modification of Lippman's test). The following 3 stages in the development of pseudoperception are described: sensorial, hallucinoid, hallucinatory. A parallel study of visual dark adaptation (40 cases) and brain bioelectrical activity (37 patients) detected 7 pathological types of changed time of visual dark adaptation and disorders of brain bioelectrical activity. These factors are connected with conditions of sensorial disadaptation, having a clinico-diagnostic significance.

Acute Disease↗

PubMed1977

[Neurocybernetic basis of hallucinations and related illusions].

Present concepts of circuits of neurons involved in the development of regular perception are used as a basis for discussing possible processes proceeding in these circuits and producing hallucinations and other illusions and false perceptions in mental patients or normal subjects.

Affective Symptoms↗

PubMed1976

Psychohysical hallucinations of orientation and spatial frequency.

After inspection of vertical sinusoidal gratings at least three distinct types of subjective or "hallucinated" patterns can be seen on a uniform test field. One type, here called horizontal streaming (H), is already well-known from the work of MacKay. A second type (V) looks like aroughly sinusoidal grating about 1-5 octaves above the adapting spitial frequency. Under optimal conditions a second vertical component appears at about 2 octaves below the adapting frequency. The third category of aftereffect consists of diagonal lines (D) at two orientations (about +/-40 degrees from vertical). The spatial-frequency band at these two orientations appears to be fairly broad, but roughly similar to the adapting frequency. The duration and strength of D increased, while V declined, at higher adapting spatial frequencies. D and V were increasing functions of adapting contrast, while H appeared abruptly only after the highest adapting contrast. H, D, and V are thus all functionally distinct. A schematic model of cortical organization is proposed to account for these phenomena. Pattern channels selective for a given orientation are grouped together with movement channels selective for the orthogonal direction. Antagonism between channels within such "modules" accounts for the streaming effect (H). Inhibition between modules tuned to different orientations and spatial frequencies accounts for the D and V effects: after adaptation of channels in one module, neighbouring module(s) are released from inhibition to produce a spurious response which is seen as a grating-like object in the adapted part of the visual field. During flickering adaptation a "halluncinated" lattice can be seen superimposed on the adapting grating. It apparently consists of Fourier components more remote from the adapting pattern than D and V are. This disinhibitory effect is strong confirmation of the inhibitory model. The regular and highly organized matrix of channels implied by these experiments may constitute a cortical hypercolumn conducting a coarse, piecewise Fourier transformation of the retinal image.

Figural Aftereffect↗

PubMed2025

Privacy-hardened and hallucination-resistant synthetic data generation with logic-solvers.

MOTIVATION: Machine-generated or synthetic data is a valuable resource for training artificial intelligence algorithms, evaluating rare workflows, and sharing data under stricter data legislations. However, current statistical and deep learning methods struggle with large data volumes, are prone to hallucinating scenarios incompatible with reality, and seldom quantify privacy meaningfully. RESULTS: Here, we introduce Genomator, a logic solving approach (SAT solving), which efficiently produces private and realistic representations of the original data. We demonstrate the method on genomic data, which arguably is the most complex and private information. We benchmark Genomator against state-of-the-art methodologies (Markov generation, Wasserstein Generative Adversarial Network and Conditional Restricted Boltzmann Machines), demonstrating a 40%-530% accuracy improvement and 57%-172% higher privacy. Genomator is also 3-100 times more efficient, making it the only tested method that scales to whole genomes. We show the universal trade-off between privacy and accuracy, and use Genomator's tuning capability to cater to all applications along the spectrum, from provable private representations of sensitive cohorts, to datasets with indistinguishable pharmacogenomic profiles. Demonstrating the production-scale generation of tuneable synthetic genomes hold great potential for balancing underrepresented populations in medical research and advancing global data exchange. AVAILABILITY AND IMPLEMENTATION: Genomator is available at https://github.com/csiro/genomator.

Algorithms↗