Phenytoin and phenobarbital: A comparison of their state-dependent effects

Kumar, K. B.; Ramalingam, S.; Karanth, K. S.

doi:10.1016/0091-3057(94)90302-6

Cited by 3 publications

(2 citation statements)

References 22 publications

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“…As in other memory research (Morris et al, 1982), the procedure defines response latency as the dependent variable, but applies it to the completion of a fixed-ratio 10 (FR10) schedule of lever presses on a single lever. Studies comparing this single-lever StD procedure with a widely used two-lever DD procedure have indicated that the paradigms can generate different outcomes (Colpaert and Koek, 1995), corroborating other data that discriminative effects cannot account for StD (Pusakulich and Nielson, 1976;Nielson et al, 1978;Oberling et al, 1993;Kumar et al, 1994).…”

supporting

confidence: 72%

Opiate States of Memory: Receptor Mechanisms

1999

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The present studies characterized the receptor mechanisms of morphine-induced states of memory. Morphine (5 mg/kg) produced a state in which rats could learn and retrieve an operant response; retrieval was impaired, however, when the rats were tested in the normal state. Conversely, rats that were trained in the normal state failed to retrieve the response in the morphine state. In either case the mnesic state was dose dependent, commencing at morphine doses as low as 0.8 mg/kg. In rats trained with 5 mg/kg of morphine, retrieval was fully adequate when tested with this same dose but not when tested with either lower or higher doses. Naloxone, but not naltrindole, antagonized the morphine-induced state; heroin and (Ϫ)cyclazocine, but not U50,488H, (ϩ)-cyclazocine and SNC80, produced a state in which retrieval occurred at least partially. Time-effect studies in which injections were made from 0 to 240 min before the sessions indicated that the retrieval in saline-tomorphine and morphine-to-saline conditions occurred along different time courses; a theory of opiate signal transduction suggests that these temporal profiles result from morphine producing two bi-directional mnesic states that may differ as much as the analgesia and hyperalgesia that morphine also induces. It appears that a particular magnitude of opiate receptor activation produces a state to which a memory trace can be confined in a highly selective manner. The normal and this particular morphine state are only some of the many mutually inaccessible and molecularly definable states of memory that are likely to exist, thus challenging the unitary concept of an individual organism's memory.

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supporting

confidence: 72%

Opiate States of Memory: Receptor Mechanisms

1999

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“…It has been argued, however, that the StD and DD paradigms differ in the stimulus properties of drugs which they measure, and may therefore generate different outcomes reflecting different neurobiological phenomena (Colpaert et al 1976;Colpaert 1977a, b). Consistent with this view, Pusakulich and Nielson (1976;see also Nielson et al, 1978;Kumar et al 1994) contended that the possible DS effects of drugs are inadequate in accounting for StD. Also, DD can be achieved with peripheral agents (Colpaert et aL 1975b) whereas StD is believed (Roffman and Lal 1972;Overton 1974) to occur only with compounds that act directly on the central nervous system.…”

Section: Introductionmentioning

confidence: 68%

Empirical evidence that the state dependence and drug discrimination paradigms can generate different outcomes

Colpaert

Koek

1995

Psychopharmacology

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The study compared the outcomes generated by the State Dependence and Drug Discrimination paradigms with ethanol in the rat. Food-deprived rats learned to complete a fixed-ratio 10 schedule of bar presses for food within 120 s while treated with 320- to 1250-mg/kg doses of ethanol. Subsequent tests of recall of this response with saline failed to generate any evidence that transfer was hampered following the drug-to-saline state change. In contrast, each of 14 rats learned to discriminate 1250 mg/kg ethanol from saline in a Drug Discrimination procedure that also required the animals to press one of two levers for food according to a fixed- ratio 10 schedule. The results offer the first empirical evidence to demonstrate directly that the State Dependence and Drug Discrimination paradigms can generate different outcomes in otherwise identical experimental conditions.

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