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  • 1
    Electronic Resource
    Electronic Resource
    Dissociable effects of d-amphetamine, chlordiazepoxide and α-flupenthixol on choice and rate measures of reinforcement in the rat (1983)
    Springer
    Psychopharmacology 79 (1983), S. 180-186 
    Details
    ISSN: 1432-2072
    Keywords: Reinforcement ; Non-reinforcement ; Rate ; Choice ; Win-stay ; d-Amphetamine ; Chlordiazepoxide ; α-Flupenthixol ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The role of reinforcers in influencing choice was studied by use of a schedule that included a random intermixing of reinforced and explicitly non-reinforced components. The just-reinforced response had a high likelihood of being repeated (win-stay), although there was no differential reinforcement for doing so, whereas responses just followed by explicit non-reinforcement had a very low probability of repetition (lose-stay). Non-parametric indices based on the theory of signal detection were used to derive a choice measure of reinforcement which was independent of alterations in average response rate. Treatments with d-amphetamine (0.2–4.5 mg/kg), chlordiazepoxide (0.25–16 mg/kg) and α-flupenthixol (0.03–0.6 mg/kg) showed that changes in the choice measure could be dissociated from changes in the response rate. These findings were supported by extinction and satiation tests.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00427808
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  • 2
    Electronic Resource
    Electronic Resource
    Depletion of unilateral striatal dopamine impairs initiation of contralateral actions and not sensory attention (1985)
    [s.l.] : Nature Publishing Group
    Nature 313 (1985), S. 679-682 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In procedure (1), two groups of rats were trained to hold their heads in a central hole until an eccentric visual stimulus was presented to one or other side of the head. The two groups were required to report the presence of the light either by moving their heads towards it (SAME group, n = 6) or ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/313679a0
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  • 3
    Electronic Resource
    Electronic Resource
    Delay-dependent short-term memory deficits in aged rats (1988)
    Springer
    Psychopharmacology 96 (1988), S. 174-180 
    Details
    ISSN: 1432-2072
    Keywords: Aging ; Short-term memory ; Delayed response ; Delayed matching ; Delayed non-matching ; Arecoline ; Physostigmine ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Separate groups of rats of three ages (6 month, 15 month or 24 month) were trained in a two-lever operant chamber on one of two versions of a paired-trial delayed response task involving either matching or non-matching of the choice response to a sample lever. The older rats were unimpaired in learning either version of the task during initial training with no (0 s) delay between the sample and choice responses. However, when variable 0–24 s delay intervals were introduced, the 24-month group was impaired on acquisition of the delayed non-matching task, and both the 15- and 24-month groups were impaired on acquisition of the delayed matching task compared to the 6-month group. Deficits in the older groups in asymptotic performance were attributable to an impairment at longer delay intervals whilst maintaining near perfect performance at the shorter delay intervals, suggesting a selective short-term memory impairment. The delay-dependent deficits of the older groups were not ameliorated by the muscarinic agonist arecoline or the cholinesterase inhibitor physostig-mine, and so failed to corroborate a cholinergic interpretation of the observed age-related impairment in short-term memory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00177557
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  • 4
    Electronic Resource
    Electronic Resource
    A comparison of the effects of amphetamine, apomorphine and white noise on response switching in the rat (1989)
    Springer
    Psychopharmacology 97 (1989), S. 238-242 
    Details
    ISSN: 1432-2072
    Keywords: Amphetamine ; Apomorphine ; Arousal ; Behaviour pattern
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of d-amphetamine, apomorphine and white noise on response switching in the rat were examined using a schedule of reinforcement which resulted in the subjects displaying a range of different probabilities of switching. The procedure was analogous to the use of a fixed interval schedule of reinforcement for examining the ratedependent effects of drugs. d-Amphetamine (0.4–4.0 mg/kg) increased response switching in a manner dependent both upon the dose of drug and the baseline probability of switching. Apomorphine (0.01–0.3 mg/kg) increased switching in a manner which depended upon dose but which was independent of the baseline probability of switching. Neither drug increased response rate, although both drugs reduced response rate at the highest doses. In contrast, continuous white noise (85–105 dB) increased response rate without affecting switching. The results indicate that different activating stimuli may have qualitatively different effects on behaviour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00442257
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  • 5
    Electronic Resource
    Electronic Resource
    Increased response switching, perseveration and perseverative switching following d-amphetamine in the rat (1983)
    Springer
    Psychopharmacology 80 (1983), S. 67-73 
    Details
    ISSN: 1432-2072
    Keywords: Amphetamine ; Stereotypy ; Locomotor activity ; Switching ; Perseveration ; Attention ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Four experiments examined the effects of d-amphetamine on response switching and perseveration in apparatus allowing a choice of response location. The relative ‘cost’ of a switch between two response locations and repetitive responding at a single location by rats was manipulated in the various test settings to provide baseline probabilities of switching. d-Amphetamine (0.2–2.3 mg/kg) increased response switching. This effect did not depend on switching being necessary to produce reinforcement and was not explained by increases in locomotor activity, motivational change or randomisation of responding. Further evidence was provided in support of a ‘probability-dependency’ hypothesis, that the effect of the drug depends in part upon the baseline probability of a response. A measure of perseveration independent of response switching (extra responses made prior to the collection of food) showed that increased switching and increased perseveration occurred in the same situation at the same doses, although perseveration generally occurred at higher doses than increased switching. Therefore the effect of amphetamine on response switching or repetition depends on the dose of drug, the context of the response and its probability of occurrence under control conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00427498
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  • 6
    Electronic Resource
    Electronic Resource
    Effects of repeated treatment with 5-HT1A agonists on active avoidance responding in the rat (1993)
    Springer
    Psychopharmacology 112 (1993), S. 45-54 
    Details
    ISSN: 1432-2072
    Keywords: Serotonin agonist ; 8-OH-DPAT ; Flesinoxan ; Ipsapirone ; Buspirone ; Haloperidol ; Active avoidance ; Rats ; Repeated treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The behavioural effects of the serotonin 1A receptor (5-HT1A) agonist anxiolytics are generally examined after acute administration. The present study examined the effects of these substances during repeated treatment in the two-way active avoidance (Conditioned Avoidance Response, CAR) procedure. Previously it has been found that the prototypical 5-HT1A receptor agonist, 8-OH-DPAT, increases avoidance, apparently by increasing general activity, after repeated administration but not on acute administration. In the present study, it was demonstrated that this increase in activity can be blocked by the 5-HT1A receptor antagonists (−)alprenolol (also beta adrenergic antagonist) and (S)-UH-301, but not by the non-selective 5-HT antagonist metergoline. The relatively full 5-HT1A agonist, flesinoxan, and the partial 5-HT1A agonist, ipsapirone, had qualitatively similar effects to 8-OH-DPAT, although the effect of ipsapirone was clearly smaller in magnitude. Buspirone, the 5-HT1A partial agonist/dopamine D2 antagonist, markedly decreased activity, and thus avoidance of the shocks, in a manner similar to the antipsychotic drug, haloperidol. However, when the hypothermic effects of these compounds were investigated after acute administration, buspirone induced a strong hypothermic response in rats, like 8-OH-DPAT, whereas haloperidol had no effect. With the exception of buspirone, the effectiveness of these compounds in increasing activity in the CAR test appears to be related to their agonist efficacy at the 5-HT1A receptor. Similarities between the effects of these compounds and previously reported results with serotonin-depleting agents (Tenen 1967; Breese et al. 1974) suggest that the net effect of 5-HT1A agonists after repeated administration is to produce a functional reduction in 5-HT activity. The activity suppressing action of buspirone indicates that the dopamine antagonist activity of buspirone predominates in this procedure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02247362
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  • 7
    Electronic Resource
    Electronic Resource
    Effects of 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) after repeated administration on a conditioned avoidance response (CAR) in the rat (1992)
    Springer
    Psychopharmacology 109 (1992), S. 134-144 
    Details
    ISSN: 1432-2072
    Keywords: Conditioned avoidance response ; 8-OH-DPAT ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract 8-OH-DPAT, a selective 5-HT1A agonist, has variously been found to impair, have no effect on or enhance the conditioned avoidance response (CAR). Procedural differences may account for the difference in results. In the first experiment in the present study rats were trained in the two-way active avoidance procedure to a criterion of 65% avoidance. Separate groups of rats were treated with 0.01, 0.1 or 1.0 mg/kg 8-OH-DPAT SC once per day for 14 days. The rats were tested in the CAR each day 5 min after treatment, using a 10 s light and tone conditioned stimulus and five 0.2 mA/0.5 s electric shocks. On the first day the doses of 0.1 and 1.0 mg/kg impaired avoidance, but by the end of training these two doses increased avoidance. This change in effect was accompanied by a 15-fold increase in the number of trials in which the subject crossed during a 10 s period of the ITI, which in turn led to a significant impairment in the discrimination ratio. The results of this experiment show that with repeated treatment 8-OH-DPAT changes from being antipsychotic like to being stimulant-like. The latter effect produces an improvement in avoidance, probably due to a non-specific increase in activity. In the second experiment, the rats were divided into groups based upon the undrugged performance. The avoidance-enhancing effect of 8-OH-DPAT was greater in magnitude in a group of poor performers, but was qualitatively similar in good performers. In the second stage of the experiment, gradual withdrawal from the drug was compared with sudden withdrawal. In the gradual withdrawal group, a reduction in the dose from 0.085 mg/kg to 0.01 mg/kg resulted in a gradual disappearance of the enhanced activity. There was an almost linear relationship between performance and the log dose of the drug, suggesting that the increase in activity seen after repeated administration of 8-OH-DPAT is directly related to the acute level of drug administered. This effect was evident in both good and poor performers. On the basis of these results it is suggested that many, but not all, antidepressant-like effects of 8-OH-DPAT may result from changes in activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02245491
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  • 8
    Electronic Resource
    Electronic Resource
    The effects of repeated treatment with 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) on the lever press responding of the rat under FI and DRL schedules of food reinforcement (1995)
    Springer
    Psychopharmacology 120 (1995), S. 81-92 
    Details
    ISSN: 1432-2072
    Keywords: Serotonin1A agonist ; 8-OH-DPAT ; Lever pressing ; Stimulant ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In general, the effects of 8-OH-DPAT on the body temperature of rats or in inducing the 5-HT syndrome show rapid tolerance. However, in contrast, the 8-OH-DPAT-induced increase in the activity of rats in a two-way active avoidance task only occurs after repeated administration, i.e. there is sensitisation. The present study was conducted to examine whether this developing hyperactivity may also be expressed as increased rates of lever press responding, and if so, under which conditions it occurs. Rats were trained to press levers under fixed interval 60-s (FI 60) or differential reinforcement of low rates 20-s or 72-s (DRL20, DRL72) schedules of food reinforcement. Groups of trained rats were then treated daily 5 min before testing with doses of 0.01, 0.1 and 1.0 mg/kg 8-OH-DPAT SC for 10–21 days. In all three procedures, in the first couple of days of drug treatment, 8-OH-DPAT generally suppressed lever pressing in a dose-dependent manner. Thereafter, tolerance to this effect was seen to a greater (DRL20, DRL72) or lesser (FI60) extent. Some evidence for stimulation of low rates of lever press responding was seen after 10 days treatment under FI60, but not in DRL20 or DRL72 during short 30 to 60 min long daytime tests although in the latter case, the rats responded to the stimulating effects of 0.8 mg/kg SC amphetamine administered once at the end of the experiment. However, when rats were allowed to respond under DRL72 testing for 12 h during the night, after 10 days treatment a clear stimulation of lever pressing was observed. This stimulation was not specific to lever pressing, however, since a stimulation of entries into the food tray and licking were also seen. From these results, it may be concluded that the stimulating effect of 8-OH-DPAT after repeated administration may be expressed as increased rates of lever pressing, but not under all conditions in which psychomotor stimulation by amphetamine is seen. The potential for 8-OH-DPAT and related compounds to stimulate motor responding in this way should be taken into account when interpreting the effects of these drugs in animal models of psychiatric disorders.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02246148
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  • 9
    Electronic Resource
    Electronic Resource
    The pharmacology of impulsive behaviour in rats V: the effects of drugs on responding under a discrimination task using unreliable visual stimuli (1999)
    Springer
    Psychopharmacology 143 (1999), S. 111-122 
    Details
    ISSN: 1432-2072
    Keywords: Key words Reaction time ; Impulsivity ; Desipramine ; Clomipramine ; d-Amphetamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Impulsivity is widely considered to be multifactorial. One factor, frequently termed “reflection-impulsivity”, refers to the need to give time to information analysis and reflection before making a response. In most reaction time tasks employed for non-human subjects, responding is expected immediately after a specific stimulus has been presented. In the present experiment, the need to wait before responding was made explicit by using a signal which increased in predictive value the longer the subject (a rat) waited before responding. First, the rats learned that a light signal indicated the availability of a food reinforcer if one of two levers was pressed. In the test procedure, on each trial, when the light was turned on it was only 50% likely to indicate the “correct” lever. After a brief interval it was turned off and on again, this time with a slightly higher probability (〉50%) of indicating the correct lever. Over a period of a few seconds the probability that the light indicated the correct lever increased to almost 100%. Thus a quick response to the light would result in many errors, whereas a slow response could always result in food delivery. Once trained the rats were treated with a series of drugs: haloperidol (0.01–0.1 mg/kg), chlordiazepoxide (1–10 mg/kg), ethanol (100–1000 mg/kg), d-amphetamine (0.4–1.2 mg/kg), metergoline (0.3–3.0 mg/kg), imipramine, desipramine and clomipramine (all 1, 3 and 10 mg/kg), as well as being given additional food just prior to testing. Ethanol and clomipramine had no effects on behaviour in the dose range tested. Amphetamine did not affect accuracy and had no effect on reaction time. The other drugs all reduced the number of short reaction times and thereby increased overall accuracy. Additional feeding, chlordiazepoxide and haloperidol also increased selectively the accuracy of responses made with short reaction times. These results can be interpreted by supposing that desipramine and imipramine specifically reduced impulsivity whereas additional feeding, chlordiazepoxide, haloperidol increased the response criterion. The pharmacological specificity of the tricyclics suggests that stimulation principally of the noradrenergic system (via desipramine), but not necessarily the serotonergic (clomipramine) or dopaminergic (amphetamine) improves performance in this procedure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050926
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  • 10
    Electronic Resource
    Electronic Resource
    Caffeine and nicotine improve visual tracking by rats: a comparison with amphetamine, cocaine and apomorphine (1993)
    Springer
    Psychopharmacology 110 (1993), S. 169-176 
    Details
    ISSN: 1432-2072
    Keywords: Stimulants ; Amphetamine ; Apomorphine ; Cocaine ; Caffeine ; Nicotine ; Performance enhancement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Psychomotor stimulant drugs such as caffeine, nicotine, amphetamine and cocaine, have been shown to improve vigilance in man under conditions of fatigue. Nicotine has also been shown to improve performance in some cognitive tests in patients with Alzheimer's disease. In rodents these drugs increase activity which may confound “performance enhancing effects” in rodent models. However, improvements have been found in a number of tests that do not seem to be directly dependent upon an enhancement of locomotor activation. In one example, Evenden and Robbins (1985) reported consistent improvements in a visual tracking test following amphetamine. The present study was undertaken to determine whether these performance enhancing effects of amphetamine could also be obtained with cocaine and apomorphine, which both have psychomotor stimulant effects through their actions as, respectively, indirect and direct dopamine agonists, and by caffeine and nicotine, which do not have a direct dopaminergic mechanism of action. The results of the study indicate that all five drugs improved tracking performance at one or more doses. The most consistent effects were obtained with amphetamine which, like cocaine and nicotine, improved tracking at a dose which did not produce other changes in behaviour. Taking into account previous studies (Evenden and Robbins 1983, 1985), these results were interpreted as indicating that psychomotor stimulant drugs produce ageneral activation of behaviour. At all but the highest doses of such drugs, the form of behaviour that is observed depends upon the environment. The results of this study support the conclusion that in the situation where stimuli are present which exert a strong control over behaviour in the undrugged state, then the stimulated behaviour will be directed towards those, and may result in an enhancement of performance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02246968
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