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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: 3,4-Dihydroxyphenylethylamine (DA, dopamine) and 5-hydroxytryptamine (5-HT) turnover values were determined in freely moving male rats by measuring the rates of accumulation of the acidic metabolites of the above transmitters, i.e., 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA) in cisternal cerebrospinal fluid (CSF) samples after probenecid (200 mg/kg i.p.) administration. Determinations on samples before and after acid hydrolysis showed that the latter procedure was necessary for DA turnover determination. Thus whereas total (DOPAC + HVA) increased linearly with time after probenecid, free (DOPAC + HVA) did not. This was because the percentage of DOPAC + HVA in conjugated form increased with time. Determinations on a group of 28 rats during the dark (red light) period showed that cisternal amine metabolite concentrations before probenecid injection did not parallel turnover values. This was probably because individual differences in metabolite egress strongly affect the pre-probenecid values. The poor correlations between CSF tryptophan and 5-HT turnover suggested that differences of brain tryptophan concentration were not major determinants of differences of brain 5-HT metabolism within this group of normal rats. Considering that the rats were of similar weight and that the turnover values were all determined at approximately the same time of day, the three- to fourfold ranges of the turnover values are remarkable. The positive correlation between the DA and 5-HT turnovers of individual rats suggests the existence of common effects on DA and 5-HT turnover in normal rats.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing
    Psychophysiology 36 (1999), S. 0 
    ISSN: 1469-8986
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Physiological response stereotypy is a well-established psychophysiological construct. Unfortunately, specifying parameters of tasks that evoke differing physiological responses has proved difficult. We have recorded cardiovascular activity while subjects carried out executive and attentional tasks that differed not only psychologically but also in their sensitivity to brain pathology and to pharmacological manipulations. Finapres recordings were made of 30 healthy, normal subjects (mean age 24 years) performing two tasks involving differing aspects of sustained attention and two tasks involving differing aspects of spatial working memory and planning. Measures of heart rate and blood pressure, heart rate and blood pressure variability, and their spectral derivatives revealed differing patterns of cardiovascular adjustment between the “attentional” and “planning” tasks. Each test raised blood pressure, but changes in blood pressure and heart rate variability were confined to the attentional tasks. These findings suggest distinct brain mechanisms subserving different forms of arousal.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 473 (1986), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 279 (1979), S. 731-732 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Weanling, male Sprague-Dawley rats were housed at six per cage and given free access to food and water. Half of the rats were fed a corn-based diet containing Masa Harina as the source of protein and carbohydrate (low tryptophan rats) and the other half were fed an 18% casein diet (control rats). ...
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-2072
    Keywords: Rating scales ; Photocell activity cages ; Measurement ; Stereotypy ; d-Amphetamine ; Apomorphine ; Dopamine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A novel means of measuring and analysing behavioural effects of dopamine agonists is described and illustrated by a comparison of the effects of d-amphetamine and apomorphine in the rat. d-Amphetamine (0–15 mg/kg IP) produced significant dose- and time-dependent changes in responses such as locomotion, rearing and sniffing, but not in licking or gnawing. In contrast, apomorphine (0–5 mg/kg SC) produced significant increases in licking and gnawing, as well as in locomotion and sniffing, but no changes in rearing. The results are discussed in comparison with those obtained by other methods, such as photocell beam interruptions or stereotypy rating scales, and may be of importance in elucidating the functions of the forebrain dopamine projections.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-2072
    Keywords: Nicotine ; Alzheimer's disease ; Attention ; Information processing ; Short-term memory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This single-blind, placebo controlled study reports on the effects of administering three acute doses of nicotine (0.4, 0.6 and 0.8 mg) subcutaneously to a group of Alzheimer's disease (DAT) patients (n=22), young adult controls (n=24), and normal aged controls (n=24). The study extends our previous findings obtained using smaller groups of subjects. Drug effects were examined on three computerised tests: the first measuring rapid visual information processing, sustained visual attention and reaction time (RVIP task); a delayed response matching to location-order task measuring sustained visual attention and visual short-term memory (DRMLO task); and a finger tapping test measuring simple reaction time (FT task). The critical flicker fusion test (CFF) was used as a measure of perception and the WAIS digit span forwards (DS), of auditory short-term memory. Tests were graded in difficulty, titrated to avoid floor and ceiling effects so that meaningful, direct comparisons between groups could be made. Nicotine significantly improved sustained visual attention (in both RVIP and DRMLO tasks), reaction time (in both FT and RVIP tasks), and perception (CFF task — both ascending and descending thresholds). Nicotine administration did not improve auditory and visual short-term memory. There were no consistent, overall patterns of difference in performance between smokers and non-smokers in the control groups, or between males and females in any group. Despite the absence of change in memory functioning, these results demonstrate that DAT patients have significant perceptual and visual attention deficits which are improved by nicotine administration. The importance of measuring multiple abilities in future drug studies is emphasized and results are discussed in terms of nicotine's actions on attention, information processing and short-term memory.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-2072
    Keywords: Key words Psychomotor stimulant ; Dopamine ; Cognition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Previous studies of the effects of the psychomotor stimulant, methylphenidate, have concentrated on vigilance and reaction time tasks. In this study, the effects of methylphenidate on more complex aspects of cognition were studied using tasks from the CANTAB battery and related tests which have been shown to be sensitive to frontal lobe dysfunction. Twenty-eight young healthy men participated in a counterbalanced, double-blind, placebo-controlled study of the effects of methylphenidate. Cognitive assessment included tests of spatial working memory, planning, verbal fluency, attentional set-shifting and sustained attention. Methylphenidate had significant effects on performance of the tests of spatial working memory and planning but not on the attentional and fluency tests. When the drug was taken on the first test session, performance on the spatial tests was enhanced by the drug compared to placebo. However, when the drug was taken second, performance accuracy was impaired whereas response latencies were decreased. These results are consistent with a hypothesis that methylphenidate influences performance in two conflicting ways; enhancing executive aspects of spatial function on novel tasks but impairing previously established performance. This pattern of effects is discussed within the framework of dual, interacting arousal mechanisms.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-2072
    Keywords: Key words Learning ; Memory ; Hydrocortisone ; Frontal lobe ; Normal volunteers ; Frontal lobe dysfunction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Rationale: Corticosteroids are elevated in certain neuropsychiatric disorders and this may contribute to the neuropsychological impairments reported in these disorders. Objective: To examine the effects of hydrocortisone on learning, memory and executive function. Methods: Hydrocortisone 20 mg was administered twice daily for 10 days to normal male volunteers in a randomized, placebo control, crossover, within-subject design. Learning, memory and executive function were measured using selected subtests from the Cambridge Neuropsychological Test Automated Battery. Results: Hydrocortisone caused impairments of visuo-spatial memory. These included increased within search errors and impaired use of strategies on the spatial working memory subtest. In addition, administration of hydrocortisone was associated with more errors in the paired associate learning subtest, although no effect was found on the Tower of London. Hydrocortisone speeded response latencies in certain tests (pattern and spatial recognition memory). Conclusion: These results indicate that chronic administration of hydrocortisone leads to deficits in certain tests of cognitive function sensitive to frontal lobe dysfunction and may contribute to the cognitive impairment reported in certain neuropsychiatric disorders.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-2072
    Keywords: Key words Dopamine ; Sulpiride ; Cognition ; Working memory ; Attention
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Rationale: The mesotelencephalic dopamine system has been implicated in cognitive processes dependent on an intact prefrontal cortex. Most previous research in humans has focused on dopaminergic agonists and their effects on tasks of working memory. Objectives: The present study was designed to investigate the cognitive and subjective effects of two doses (200 mg and 400 mg) of the dopaminergic D2 receptor antagonist, sulpiride on a broad range of well-validated neuropsychological tasks in a group of 34 young healthy male volunteers. Methods: Cognitive tasks were administered to subjects after ingestion of either drug or placebo within a double-blind, placebo-controlled, cross-over design. The cognitive tests included tasks from the Cambridge Neuropsychological Test Automated Battery (CANTAB) and were designed to assess visuospatial recognition memory, planning ability, working memory, strategy learning, sustained attention and attentional set-shifting. In addition, the National Adult Reading Test (NART) was used to assess verbal IQ, and visual analogue scales to assess subjective effects of the drug. Results: Subjects on sulpiride were impaired on the tasks of spatial recognition, spatial working memory (sequence generation), planning (one-touch Tower of London) and attentional set-shifting. Only the spatial working memory task demonstrated a dose dependent effect. The impairments were not due to generalised sedative or motoric influences of sulpiride. Conclusions: All of the tasks impaired following sulpiride are known to be sensitive to frontal lobe damage and the precise pattern of deficits seen is consistent with the anatomical distribution of central dopamine receptors. The results are discussed with particular reference to their close simulation of the impairments seen in idiopathic Parkinson’s disease.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 45 (1975), S. 115-117 
    ISSN: 1432-2072
    Keywords: Stereotyped behavior ; Amphetamine-Environmental influence ; Conditioning ; Stimulus control ; Rearing experience ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Ten socially deprived and 10 control guinea pigs were injected with 5.0 mg/kg d-amphetamine, and stereotypy was rated over 1 hr. The animals were tested in a novel environment, in a familiar environment, and again in the novel environment. Stereotypy was reduced in the novel environment. An increase in stereotypy between the test in the novel environment and the retest in the novel environment indicated a conditioning effect. Regardless of environment, controls showed greater stereotypy than socially deprived guinea pigs. The results are discussed in terms of the variables which determine the form and intensity of stereotyped behavior.
    Type of Medium: Electronic Resource
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