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Results for “Perceptual Disorders”

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At least 91 records · Page 5Linked to original sources
PubMed1969

The effect of a large dose of atropine upon the performance of routine tasks.

1. A field trial was conducted in order to assess the effect upon tasks, including hard labour, skilled work, the use of instruments and tools and shooting, of giving 6 mg of atropine sulphate by injection to twenty-three adult male volunteers.2. Impairment of performance was seen in these tasks under the influence of the drug, but this was statistically significant only in some of them.3. Drowsiness occurred in twenty-one men and perceptual disorders were common, but two men were almost completely resistant to the effects of the drug.4. The implications of the therapeutic use of comparable doses of atropine are discussed.

Atropine↗
PubMed1977

Visuo-spatial performance following posterior parietal and lateral frontal lesions in stumptail macaques.

Three groups of four monkeys were trained to negotiate a small hand ("stylus") maze, and to use a "pointer" to guide response in a two-choice position discrimination task. One group was given bilateral lesions of posterior parietal cortex, and the second bilateral lesions of lateral frontal cortex. Postoperative impairment on the maze was evident in three of the four parietal animals, and both operated groups showed impairment on the pointer task. Since maze performance was positively associated with speed of stylus recovery in a control version of the task but was not correlated with pointer task performance, it is suggested that the parietal deficit resulted primarily from a sensory-motor dyscoordination rather than a spatial perceptual disorder. The latter could however be the cause of parietal impairment on the pointer task. Error analysis suggests an interpretation of the frontal deficit on the pointer task in terms of perseveration on position.

Animals↗
PubMed1993

Adverse consequences of lysergic acid diethylamide.

The continued endemic use of hallucinogenic drugs, and of LSD in particular, raises concern regarding their short and long term adverse consequences. The epidemiology of LSD abuse is reviewed suggesting an increase in LSD use among the young as the prevalence rates for other substances continues to fall. Evidence supports the association of LSD use with panic reactions, prolonged schizoaffective psychoses and post-hallucinogen perceptual disorder, the latter being present continually for as long as 5 years. Evidence does not support claims of genetic disorders arising from hallucinogens. In light of the foregoing, current data confirm earlier findings of long lasting psychopathology arising in vulnerable individuals from the use of LSD. A hypothetical long term molecular mechanism of adverse effects is proposed.

Adolescent↗
PubMed1995

There's more to colour than meets the eye.

Patients with cerebral achromatopsia, a perceptual disorder caused by ventromedial occipital brain damage, can be completely unable to arrange colours in chromatic sequence and fail most conventional tests of colour blindness. A possible explanation for cerebral achromatopsia is that the colour-opponent parvocellular (P) channel has been selectively and totally destroyed at the level of visual cortex, leaving vision to be mediated by the broad-band magnocellular (M) channel. The persistence of normal occipital visually evoked potentials, and preserved sensitivity to isoluminant chromatic gratings indicates that if this hypothesis is correct the destruction must occur beyond the striate cortex. We have shown that an achromatopsic subject can detect chromatic borders and construct shape from colour, and that he can even perceive the apparent direction of motion of a phase shifted isoluminant chromatic grating where perceived direction depends on knowing the sign of the colour diffence, i.e., which colour is which in the stripes. This and other evidence suggests that perhaps only one part of the cortical P channel has been destroyed. Does the critical area involved in achromatopsia correspond to cortical area V4 of monkeys, often implicated in processing wavelength? When Visual Area 4 is totally ablated in monkeys they have only a mild colour discrimination impairment and easily solve the colour ordering and colour selection tasks that an achromatopsic patient finds impossible. However, monkeys with ventromedial damage rostral to Area V4 do perform like achromatopsic patients, suggesting that the role of V4 in the perception of colour is still unclear and that the colour area of the human brain does not correspond to area V4.

Animals↗
PubMed2004

Borderline personality disorder: impaired visual perception and working memory.

The neurobiology of borderline personality disorder (BPD) is still elusive. There are a few studies on neuropsychological performance in BPD, which report a broad spectrum of abnormalities. The present study evaluates perception and working memory as instances of basic cognitive functions. Female subjects diagnosed with DSM-IV borderline personality disorder (n=22) were compared with age- and education-matched controls (n=25). Perception speed was assessed by a backward masking paradigm. Working memory was tested by a series of delayed matching-to-sample paradigms involving varying subsidiary functions like mental rotation, retrieval from memory, ignoring distracters, and cross-modal performance. In backward masking, BPD subjects required significantly longer stimulus onset asynchrony (SOA) than controls to identify the visual target, and there was an additional slowing of the motor response. Working memory accuracy was impaired in BPD subjects, but did not worsen when the cognitive load was increased. With increasing task difficulty, they traded off speed for accuracy similarly as the controls. Impulsivity and dissociation ratings were not correlated with performance. It is concluded that perceptional speed and working memory are impaired in BPD, but that the deficits are not augmented by increasing cognitive load.

Adolescent↗
PubMed1983

Psychopathological effects of solitary confinement.

Psychopathological reactions to solitary confinement were extensively described by nineteenth-century German clinicians. In the United States there have been several legal challenges to the use of solitary confinement, based on allegations that it may have serious psychiatric consequences. The recent medical literature on this subject has been scarce. The author describes psychiatric symptoms that appeared in 14 inmates exposed to periods of increased social isolation and sensory restriction in solitary confinement and asserts that these symptoms form a major, clinically distinguishable psychiatric syndrome.

Adult↗
PubMed1979

The learning-disabled juvenile delinquent: a case for early intervention of perceptually handicapped children.

The relationship between learning disabilities and juvenile delinquency is examined from an historical perspective as well as from the author's investigations. The majority of studies suggest that learning disabilities occur with significant frequency in delinquent populations. Perceptual disorders can be a significant cause of academic underachievement and poor social adaptation among youthful offenders. Preliminary results of an investigation of the learning-disabled delinquent confirm that the perceptually handicapped child is at high risk for developing these behavioral problems. As one of the first professionals who may be involved in the evaluation and treatment of the perceptually handicapped child, the occupational therapist is a key person in effecting early intervention. Early intervention is considered of prime importance as one preventive measure of juvenile delinquency.

Adolescent↗
PubMed1975

Dylexia in children and young adults: three independent neuropsychological syndromes.

In an attempt to delineate causal factors in dyslexia, 113 children and young adults (age-range eight to 18 years) were divided into three groups: those with brain damage who could read (n=31), those with brain damage who were dyslexic (n=53), and those without brain damage who were dyslexic (n=29). A battery of neuropsychological tests was presented to each participant. No significant differences were found between the two dyslexic groups. Three syndromes--language disorder, articulation and graphomotor dysco-ordination, and visuo-perceptual disorder--were found among the great majority of those with dyslexia. The results support a model of dyslexia as being caused by multiple independent defects in higher cortical functioning, as opposed to the theory of a single causal defect. A clinical description of each syndrome is given and models of dyslexia are discussed. The authors stress the desirability of including brain-damaged readers as a control group in any future study on causal factors in dyslexia.

Adolescent↗
PubMed1982

The recovery of the severely disable stroke patient.

Fifty-three stroke patients with severe functional loss at two weeks, following the stroke were followed up for one year. No improvement occurred in 47% during this time and this was associated with abnormalities of muscle tone, incontinence of urine or faeces, perceptual disorders and previous disabilities affecting locomotion. Remedial therapy continued for long periods especially in the group who did not improve. It is suggested that rehabilitation resources could have been used more appropriately. Further research is required to determine whether intensive therapy is of value in the severely disabled stroke patient especially those with perceptual and cognitive dysfunction.

Activities of Daily Living↗
PubMed1998

Effects of ketamine on thought disorder, working memory, and semantic memory in healthy volunteers.

BACKGROUND: The N-methyl-D-aspartate receptor antagonist, ketamine, produces a clinical syndrome of thought disorder, perceptual distortion, and cognitive impairment. METHODS: We have administered ketamine to healthy volunteers to characterize the formal thought disorder and specific memory dysfunction associated with ketamine. Ten healthy volunteers underwent a double-blind, placebo-controlled, ketamine infusion (0.12 mg/kg bolus and 0.65 mg/kg/hour). Thought disorder was evaluated with the Scale for the Assessment of Thought, Language and Communication. Cognitive testing involved working and semantic memory tasks. RESULTS: Ketamine produced a formal thought disorder, as well as impairments in working and semantic memory. The degree of ketamine-induced thought disorder significantly correlated with ketamine-induced decreases in working memory and did not correlate with ketamine-induced impairments in semantic memory. CONCLUSIONS: This study characterizes the formal thought disorder associated with ketamine and may suggest that ketamine-induced deficits in working memory are associated with ketamine-induced thought disorder.

Adult↗
PubMed1990

Phobic anxiety and clumsiness in a 10-year-old girl.

During assessment of a girl with a long-standing phobic state, it was found that she also had previously unrecognised perceptuo-motor problems, which were associated with continuing problems in balance and spatial awareness. Her phobia improved after a desensitisation programme, but the physical disorder persisted, despite physiotherapy. The authors conclude that the girl's phobic anxiety may have had its origin in her experience of the perceptual disorder during development.

Child↗
PubMed2002

Visuomotor adaptation to optical prisms: a new cure for spatial neglect?

In this issue, McIntosh and colleagues show that visual and haptic deficits in spatial neglect can be improved following a brief period of visuomotor adaptation to rightward displacing optical prisms. Their paper is the latest in a series of recent studies that have demonstrated the utility of prismatic adaptation in reducing the clinical symptoms of unilateral spatial neglect (Pisella et al., 2002; Rode et al., 1999; Rossetti et al., 1998; Rossetti et al., 1999). The technique has great promise as a rehabilitative tool, and may provide unique insights into the underlying mechanisms of spatial perception and action in normality and pathology. In this article I provide an introduction to the neuropsychological syndrome of spatial neglect, highlighting the significant rehabilitative challenges it poses for clinicians. I then outline the prism adaptation procedure, and consider the possible reasons for its beneficial effects in patients with spatial neglect. I conclude with some open questions and suggestions for future research.

Adaptation, Psychological↗
PubMed2006

Synaesthesia for reading and playing musical notes.

This study reports three cases of synaesthesia who experience colors in response to written musical notation, graphemes and heard music. The synaesthetes show Stroop-like interference when asked to name the colour of graphemes but not for written musical notes. However, reliable interference is found in two further studies that require deeper processing of the musical notation (namely playing music from colored notation, and naming the synaesthetic color of the notes whilst suppressing the veridical color). This is the first empirical demonstration of synaesthesia for musical notation. The fact that synaesthetic color influences music playing/reading (a sensory-motor transformation) but not verbal color naming suggests that synaesthetic Stroop effects can arise from processing the meaning of a stimulus and not just as a result of verbal response interference. However, it is likely that the color associations themselves have a developmental origin in the names assigned to them. In all three cases, the colors of the written notes are related to the graphemes that arbitrarily denote them (e.g., 'A' may be "red" both as a letter and when written in musical notation). The results suggest that synaesthetic associations may migrate from one representational format (e.g., graphemes) to another (e.g., musical notation).

Acoustic Stimulation↗