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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Psychopharmacology 118 (1995), S. 195-205 
    ISSN: 1432-2072
    Keywords: Nicotine ; Mecamylamine ; Lobeline ; ABT-418 ; A-82695 ; Attention ; Vigilance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of nicotinic receptor ligands on performance in a task measuring sustained attention, or vigilance, were tested. This task required the animals to discriminate between signal and non-signal events. The sequence of signal (central panel light illumination for 500, 50 or 25 ms) and non-signal presentations was randomized over three blocks of 54 trials each (27 signal trials, 9 per length, and 27 non-signal trials). A left lever press following a signal was counted as a hit, and a right lever press following a non-signal event was counted as a correct rejection. Hits and correct rejections were rewarded, whereas misses and false alarms (defined as incorrect right and left lever presses, respectively) were not. Baseline performance was characterized by a signal length dependent ability of the animals to discriminate between signal and non-signal events. Administration of nicotine (0.19, 0.62, 1.9 µmol) or of two novel nicotinic receptor agonists, ABT-418 and A-82695, did not produce main effects on vigilance performance. Lobeline (1.9, 6.2, 19 µmol), a nicotinic receptor ligand with mixed agonist/antagonist activities, impaired the animals' ability to discriminate between signal and non-signal events. The antagonist mecamylamine (5, 15, 50 µmol) potently impaired performance while increasing the number of errors of omission. The lack of effect of nicotine largely corresponds with the findings from previous studies on the acute effects of nicotine in intact subjects and nonsmoking humans. While the detrimental effects of lobeline may have been related to the antagonist effects of this compound, the reasons for the differences between the effects of nicotine and lobeline still remain unsettled. These data support the hypothesis that nicotine receptor mechanisms are maximally activated in intact animals performing this task, and suggest that effects of acute nicotinic agonist treatment would not produce further cognitive benefit for these animals.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2072
    Keywords: Benzodiazepine receptor ; Chlordiazepoxide ; β-CCM ; Attention ; Basal forebrain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of infusions of the benzodiazepine receptor (BZR) full agonist chlordiazepoxide (CDP) or the full inverse agonist β-CCM into the basal forebrain on behavioral vigilance were tested. Vigilance was measured by using a previously characterized task that requires the animals to discriminate between visual signals of variable length and non-signal events. Measures of performance included hits, misses, correct rejections, false alarms, side bias, and errors of omission. Following the infusion of saline (0.5 µl/hemisphere), the relative number of hits varied with signal length. In response to shorter signals, the number of hits decreased over time, indicating a vigilance decrement. Infusions of CDP (20, 40 µg/hemisphere) initially decreased the relative number of hits in response to shorter signals and, later in the course of the test sessions, to longer signals as well. CDP did not affect the relative number of correct rejections. In contrast, infusions of the inverse agonist β-CCM (1.5, 3.0 µg/hemisphere) did not affect the relative number of hits but decreased the relative number of correct rejections (i.e., increased the number of false alarms). These data suggest that the basal forebrain mediates the attentional effects of BZR ligands. As systemic or intrabasalis administration of BZR agonists and inverse agonists was previously demonstrated to decrease and augment, respectively, activated cortical acetylcholine (ACh) efflux, their effects on behavioral vigilance are hypothesized to be mediated via their effects on cortical ACh.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2072
    Keywords: Key words Amphetamine ; Attention ; Sensitization ; Drug addiction ; Psychosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of repeated intermittent administration of amphetamine (1, 2, 3 mg/kg, IP) on the performance of rats in a task designed to assess sustained attention were tested. A substantial increase in the number of false alarms (i.e., “claims” for hits in non-signal trials) was observed following subsequent administrations of amphetamine. This effect could not be accounted for by drug-induced side or position biases, switching behavior or stereotypy. The effects of repeated amphetamine may model some of the cognitive processes which mediate the attribution of incentive salience to stimuli associated with repeated psychostimulant administration and the development of psychostimulant-induced psychotic symptoms.
    Type of Medium: Electronic Resource
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