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  • 1
    Electronic Resource
    Electronic Resource
    Behavioral microanalysis of spatial delayed alternation performance: rehearsal through overt behavior, and effects of scopolamine and chlordiazepoxide (1992)
    Springer
    Psychopharmacology 107 (1992), S. 263-270 
    Details
    ISSN: 1432-2072
    Keywords: Spatial alternation behavior ; Working memory ; Rehearsal ; Scopolamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rats were trained in an operant spatial delayed alternation task utilizing retention intervals from 2 to 32 s. In addition to response accuracy, operations of the levers during the retention intervals were recorded and analyzed. Animals were tested following the administration of the muscarinic antagonists scopolamine hydrobromide and methylbromide, and the benzodiazepine receptor agonist chlordiazepoxide. In vehicle-treated animals, the relative number of correct responses and correct rehearsal operations (operation of the forthcoming correct lever during retention intervals) varied with the length of the retention intervals, and these measures were correlated. The response rate for rehearsal operations increased with the length of the retention intervals. It is speculated that the delay-dependent increase in response rate reflects an effect of delayed reward that was also associated with a delay-dependent increase in the tendency to alternate between levers. The effects of delay on the accuracy of rehearsal operations may have contributed to the delay-dependent correct responding. Scopolamine hydrobromide (0.01, 0.03, 0.1, 0.3 mg/kg) and methylbromide (0.1, 0.3 mg/kg) impaired correct responding, but did not seem to interfere with the relative number of correct rehearsal operations. As only the presentation of the panel light indicated trial onset, it is speculated that the cholinergic receptor blockade resulted in an increase in the probability of a repositioning response that was triggered by light onset. Chlordiazepoxide (1, 3, 5, 10 mg/kg) did not affect behavioral performance. These results suggest that in tasks that allow the development of rehearsal operations, delay-dependent response accuracy does not represent a sufficient condition for conclusions on task demands on memory. Blockade of peripheral cholinergic receptors may account for the effects of muscarinic antagonists on performance in this task.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245146
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Attenuation of muscarinic receptor blockade-induced impairment of spatial delayed alternation performance by the triazole MDL 26,479 (1992)
    Springer
    Psychopharmacology 109 (1992), S. 223-230 
    Details
    ISSN: 1432-2072
    Keywords: Spatial alteration behavior ; Working memory ; Rehearsal ; Scopolamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The interactions between the effects of MDL 26,479 (0.1, 0.39, 1.56, 6.25 mg/kg; IP) and the muscarinic antagonist scopolamine (0.03, 0.1 mg/kg; IP) on the performance of rats in a delayed alternation task (retention intervals: 2, 4, 8, 16, 32 s) were examined. Scopolamine dose-dependently reduced the relative number of correct responses and interacted with the effects of the length of retention intervals. MDL 26,479 did not affect correct responding but attenuated the behavioral impairments produced by scopolamine. Although this task did not explicitly exclude the possibility that the animals acquired mediational response strategies, and although the effects of scopolamine appeared to interfere with the execution of these strategies, to a major extent, the attenuative effects of MDL 26,479 were not related to its effects on mediational strategies. Thus, it is concluded that administration of MDL 26,479 mainly resulted in a re-establishment of the animals' ability to memorize and/or to recall the information required to exert correct responses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245504
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Central versus peripheral effects of muscarinic antagonists: the limitations of quaternary ammonium derivatives (1992)
    Springer
    Psychopharmacology 108 (1992), S. 241-243 
    Details
    ISSN: 1432-2072
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245315
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Activating the damaged basal forebrain cholinergic system: tonic stimulation versus signal amplification (1990)
    Springer
    Psychopharmacology 101 (1990), S. 1-17 
    Details
    ISSN: 1432-2072
    Keywords: Basal forebrain ; Acetylcholine ; GABA/benzodiazepine receptor ; ZK 93 426 ; Alzheimer's disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The hypothesis that the cognitive decline in senile dementia is related to the loss of cortical cholinergic afferent projections predicts that pharmacological manipulations of the remaining cholinergic neurons will have therapeutic effects. However, treatment with cholinesterase inhibitors or muscarinic agonists has been, for the most part, largely unproductive. These drugs seem to disrupt the normal patterning of cholinergic transmission and thus may block proper signal processing. An alternative pharmacological strategy which focuses on the amplification of presynaptic activity without disrupting the normal patterning of cholinergic transmission appears to be more promising. Such a strategy may make use of the normal GABAergic innervation of basal forebrain cholinergic neurons in general, and in particular of the inhibitory hyperinnervation of remaining cholinergic neurons which may develop under pathological conditions. Disinhibition of the GABAergic control of cholinergic activity is assumed to intensify presynaptic cortical cholinergic activity and to enhance cognitive processing. Although the extent to which compounds such as the benzodiazepine receptor antagonistβ-carboline ZK 93 426 act via the basal forebrain GABA-cholinergic link is not yet clear, the available data suggest that the beneficial behavioral effects of this compound established in animals and humans are based on indirect cholinomimetic mechanisms. It is proposed that an activation of residual basal forebrain cholinergic neurons can be achieved most physiologically via inhibitory modulation of afferent GABAergic transmission. This modulation may have a therapeutic value in treating behavioral syndromes associated with cortical cholinergic denervation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02253710
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    Paper (German National Licenses)
    Fulltext
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