Differential effects of opioid and nonopioid analgesics on conditional discriminations in pigeons

Abstract

Under the fixed-consecutive-number schedule (FCN), pigeons were reinforced for responding eight or more times on one response key (work key), and then responding once on a second response key. In one component of this schedule, an external stimulus signalled the completion of the response requirement on the work key (FCN 8-SD), whereas no stimulus change was programmed under the other (FCN 8). Across a range of doses, the mu opioid agonist morphine, the kappa opioid agonist U50,488 and the opioid antagonist naloxone had no consistent effect on accuracy under either FCN schedule. Naloxone and accuracy under either FCN schedule. Naloxone and U50,488 produced a general flattening of the conditional probability functions by decreasing the conditional probability of response runs exceeding the minimum response requirement of eight consecutive responses on the work key. The sigma agonists phencyclidine and (+)N-allylnormetazocine and the nonopioid analgesics clonidine and l-nantradol produced large decreases in accuracy under the FCN 8 and small decreases under the FCN 8-SD. With the exception of (+)N-allylnormetazocine, these drugs consistently increased the conditional probability of responses runs shorter than the minimum response requirement on the work key. These findings indicate that the accuracy-altering effects of some opioid and nonopioid analgesics depend in part on the type of discrimination task.

Effects of Chlordiazepoxide and Cocaine on Concurrent Food and Avoidance‐of‐timeout Schedules

“…The behavioral effects of drugs have been shown to depend upon a number of nonpharmacological factors, including the schedule of reinforcement (e.g., Branch, 1990;Hoffman, Branch, & Sizemore, 1987;McAuley & Leslie, 1986), the degree of external stimulus control (e.g., Rees, Wood, & Laties, 1985), the species of the experimental subject (e.g., Picker & Dykstra, 1988;Picker, Heise, & Dykstra, 1987), its gender (van Haaren, Heinsbroek, Louwerse, & van de Poll, 1986), its experimental history (Urbain, Poling, Millam, & Thompson, 1978), and the nature of the event that maintains the behavior.…”

CONTROL OVER RESPONSE NUMBER BY A TARGETED PERCENTILE SCHEDULE: REINFORCEMENT LOSS AND THE ACUTE EFFECTS OF d‐AMPHETAMINE

“…One potential source of concern when using an FCN or any traditional differentiation procedure as a baseline against which to evaluate drug effects is that drug-induced disruptions in the run distribution will produce correlated changes in reinforcement probability and rate, generally decreasing criterional run frequency and consequently reinforcement density. Increasing doses of a wide variety of drugs, including various opioid agonists and antagonists (e.g., Bronson & Moerschbaecher, 1987;Picker, Heise, & Dykstra, 1987), the nonopi-205 1991) 561, [205][206][207][208][209][210][211][212][213][214][215] NUMBER 2 (SEPrEMBER) oid analgesics clonidine and 1-nantradol (Picker & Dykstra, 1988), the anticonvulsants clonazepam, ethosuximide (Picker, Leibold, Endsley, & Poling, 1986a) valproic acid, phenytoin, phenobarbital, diazepam (Picker, Leibold, Endsley, & Poling, 1986b), methsuximide, and mephenytoin (Schlinger, Wilkenfield, & Poling, 1988), the stimulants amphetamine (Laties, 1972), methamphetamine, caffeine, and methylphenidate (Mechner & Latranyi, 1963), and the anticholinergic scopolamine (Laties, 1972) all decrease the relative frequency of runs reinforced under FCN procedures. These decreases in reinforcement density are potentially important because they have been implicated in modifying both acute (e.g., Smith & McKearney, 1977) and chronic (cf.…”