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  • 1
    Electronic Resource
    Electronic Resource
    AMPA antagonists differ from NMDA antagonists in their effects on operant DRL and delayed matching to position tasks (1996)
    Springer
    Psychopharmacology 126 (1996), S. 249-259 
    Details
    ISSN: 1432-2072
    Keywords: NBQX ; GYKI 52466 ; MK 801 ; DRL responding ; Delayed matching ; AMPA antagonists ; Glutamate receptors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of NBQX (1.56–7.5 mg/kg, IP), a competitive antagonist at the AMPA type of glutamate receptor, were studied in two operant behavioural paradigms, differential reinforcement of low response rates (DRL), and delayed matching to position (DMTP), which have been shown to be sensitive to the antagonists of the NMDA type of glutamate receptor. Additionally, the non-competitive AMPA antagonist, GYKI 52466 (7.5–15 mg/kg, IP), was studied in the DRL procedure. As a positive control, the non-competitive NMDA antagonist, MK 801 (0.0125–0.1 mg/kg, IP) was studied in both procedures. During performance of the DRL schedule, MK 801 increased response rates in a dose dependent manner, and decreased the number of reinforcers obtained. The increase in response rates could be attributed to both a shift in the median inter-response time (IRT) to shorter intervals, and to a marked, dose dependent increase in the occurrence of bursts of responses (responses occurring within 3 s of a previous response). In contrast, NBQX and GYKI 52466 both decreased response rates in a dose dependent fashion, and did not shift the distribution of the IRTs, or increase the occurrence of burst responding. In the DMTP procedure, accuracy of matching decreased with increasing delay (up to 30 s, between presentation of sample and opportunity to respond). NBQX disrupted responding at a dose of 7.5 mg/kg, but lower doses were ineffective in influencing accuracy of performance of the discrimination. In contrast, MK 801 (0.1 and 0.2 mg/kg) reduced accuracy of matching at all delays, while tending to increase the speed of responding. These data demonstrate differences in the effects of AMPA and NMDA antagonists on performance of well trained operant behaviour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02246455
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Contrasting effects of the competitive NMDA antagonist CPP and the non-competitive NMDA antagonist MK 801 on performance of an operant delayed matching to position task in rats (1993)
    Springer
    Psychopharmacology 111 (1993), S. 465-471 
    Details
    ISSN: 1432-2072
    Keywords: Delayed matching to position ; Competitive NMDA antagonist ; Non-competitive NMDA antagonist ; Short term memory ; MK 801 ; CPP ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of the competitive NMDA antagonist CPP and the non-competitive NMDA antagonist MK 801 (dizolcipine) on short term working memory in the rat were investigated. The behavioural paradigm used was discrete trial, operant delayed matching to position, as originally described by Dunnett (1985), with delays of 0, 5, 15 and 30 s. These delays generated an orderly “forgetting” curve in control rats, with matching accuracy decreasing from approximately 100% at 0-s delay to approximately 75% at 30-s delay. Intraperitoneal (IP) administration of CPP (10 mg/kg) produced a markeddelay dependent impairment in performance, suggesting a specific effect on short term working memory. This effect was accompanied by a minor decrease in the speed of responding, and a slight increase in the number of missed trials. Lower doses of CPP had no significant effects on either matching accuracy or sedation. In contrast, IP administration of MK 801 (0.1 and 0.2 mg/kg) caused a markeddelay independent impairment in the accuracy of delayed matching performance, suggesting a non-specific disruption of performance. A lower dose (0.05 mg/kg) of MK 801 had no significant effect on matching accuracy. The two lower doses of MK 801 increased the number of nose pokes made during the delays and tended to increase the speed of responding, suggesting a stimulant-like action. The highest dose of MK 801 had the opposite effects and also decreased the number of trials completed. The results with CPP therefore support the hypothesized role of NMDA receptors in learning and memory, and the contrasting effects of these two NMDA antagonists support previous suggestions of different behavioural effects resulting from administration of competitive and non-competitive NMDA antagonists.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02253537
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  • 3
    Electronic Resource
    Electronic Resource
    Inbreeding in a lek-mating ant species, Pogonomyrmex occidentalis (1997)
    Springer
    Behavioral ecology and sociobiology 40 (1997), S. 79-86 
    Details
    ISSN: 1432-0762
    Keywords: Key words Inbreeding ; Ants ; Population structure ; Sampling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this paper we have two goals. First, we examine the effects of sample size on the statistical power to detect a given amount of inbreeding in social insect populations. The statistical power to detect a given level of inbreeding is largely a function of the number of colonies sampled. We explore two sampling schemes, one in which a single individual per colony is sampled for different sample sizes and a second sampling scheme in which constant sampling effort is maintained (the product of the number of colonies and the number of workers per colony is constant). We find that adding additional workers to a sample from a colony makes it easier to detect inbreeding in samples from given number of colonies; however, adding more colonies rather than more workers per colony always gives greater power to detect inbreeding. Because even relatively large amounts of sib-mating generate relatively small inbreeding coefficients, detection of even substantial deviations from random mating will require very large samples. Second, we look at the amount of inbreeding in a large population of the western harvest ant, Pogonomyrmex occidentalis. We find deviations from Hardy-Weinberg equilibrium equivalent to approximately 27% sib-mating in our population ( f = 0.09). Review of past studies on the population structure of other Pogonomyrmex species suggests that inbreeding may be a regular feature of the mating system of these ants. Although P. occidentalisis a swarm-mating species, there are a number of features of its population biology which suggest that the effective population size may be small. These include topographical variation that potentially breaks the population into demes, variation in the reproductive output of colonies, and variation in the size of reproductives produced by colonies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002650050318
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    Paper (German National Licenses)
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