Biomedical subjects

Marc N Branch

Publications and source records attributed to Marc N Branch.

13 recordsLinked to original sources

PubMed2006

Stability of cocaine dose-response functions at different inter-dose intervals.

Past research has found that daily administration of cocaine can lead to tolerance to its behavioral effects, and that tolerance can develop even when the dose is varied from day to day. The present experiment examined effects of administering varied doses of cocaine at a variety of inter-dose intervals ranging from once per week to everyday. Pigeons pecked on a fixed-ratio 20 schedule of reinforcement. A dose-response function for cocaine was assessed eight consecutive times during each of four phases of the experiment to assess the stability of effects of each dose. In Phase 1, subjects were administered a dose of cocaine or saline vehicle every seventh day. One subject developed tolerance by the end of this phase and was not studied further. In Phase 2, doses were administered every fourth day. During Phase 3, doses were administered every 2 days. In the final phase, doses were administered everyday. Dose-response curves were generally similar both within and across phases, regardless of inter-dose interval. No subjects developed tolerance during Phases 2, 3, and 4, suggesting that some aspect of the drug regimen prevented the development of tolerance when cocaine was given frequently.

Animals↗

PubMed2006

Validation of a mechanical apparatus for the measurement of avian walking.

Recent research has demonstrated that avian species may show an enhanced locomotor response to repeated drug exposure, a phenomenon called sensitization. Further research in this domain is warranted as such results not only establish the generality of previous findings, but may lend to a better understanding of sensitization in general. At present, there are no well-studied measurement devices for automating the measurement of bird movement. The present research evaluated a mechanical device comprised of moveable floor panels to assess its suitability. Evaluations of the device were made over the course of repeated cocaine administration. The results showed that there was high correspondence between the apparatus' responses and human observers' responses to movement by pigeons. The apparatus, furthermore, provided useful data on spatial orientation that revealed individual differences in the response to cocaine beyond those available from a collapsed measure of overall output. In sum, this recording strategy appears a viable instrument for the measurement of avian locomotion.

Animals↗

PubMed2006

How research in behavioral pharmacology informs behavioral science.

Behavioral pharmacology is a maturing science that has made significant contributions to the study of drug effects on behavior, especially in the domain of drug-behavior interactions. Less appreciated is that research in behavioral pharmacology can have, and has had, implications for the experimental analysis of behavior, especially its conceptualizations and theory. In this article, I outline three general strategies in behavioral pharmacology research that have been employed to increase understanding of behavioral processes. Examples are provided of the general characteristics of the strategies and of implications of previous research for behavior theory. Behavior analysis will advance as its theories are challenged.

Behavior↗

PubMed2006

Roger T. Kelleher, behavior analyst.

Roger T. Kelleher, rightly known as one of the foremost contributors to behavioral pharmacology, also made many important contributions to the experimental analysis of behavior. He participated significantly in the development of the discipline, through both his research and his editorial contributions to thisjournal. This article summarizes his contributions to the field of behavior analysis. His most significant empirical and conceptual contributions to behavior analysis came in two domains-conditioned reinforcement and the power of schedules of reinforcement. His accomplishments in these two domains still serve as principal foundations for modern research and theory.

Animals↗

PubMed2006

Stability of pigeon body weight under free-feeding conditions.

Increases in regulatory oversight of animal research require verification of effects of standard practices. There are no formal guidelines for establishing free-feeding weights in adult pigeons. In the present study, pigeons were obtained from a commercial supplier, weighed upon arrival, and then held in quarantine for 7 days with free access to food. Subsequently, still with continuous access to food, they were weighed daily for 30 days. No significant changes in weights occurred over the 30-day period for male pigeons, indicating that seven days is sufficient for establishing a baseline body weight. A secondary finding of higher day-to-day variability in the weights of female pigeons may serve as a method of sexing pigeons.

Animals↗

PubMed2005

Does habituation play a role in drug habit? Comment on McSweeney, Murphy, and Kowal (2005).

Comment on the article, "Regulation of Drug Taking by Sensitization and Habituation," by McSweeney, et al. McSweeney, Murphy, and Kowal offer the intriguing suggestion that the basic behavioral processes of habituation and sensitization play an important role in drug taking, specifically, repeated drug taking. The suggestion is noteworthy because, if correct, it, as the authors point out, could lead to new approaches to prevention and treatment, approaches that involve the use of environmental variables that are relatively accessible. I think their exposition raises several issues. A number of these questions are related to the phenomenon of drug tolerance, an outcome that can be understood as either an instance of or deriving from the process of habituation. The presentation also contains passages in which the logic is not fully clear. Another issue I have with the article is the overall logic approach on the basis of features of drug addiction.

Drug Tolerance↗

PubMed2004

Interactions among unit-price, fixed-ratio value, and dosing regimen in determining effects of repeated cocaine administration.

Previous research has shown tolerance to cocaine that was dependent on fixed-ratio (FR) parameter size in the context of a multiple FR schedule of food reinforcement. Completion of the FR requirement in these studies resulted in the same magnitude of reinforcement, regardless of ratio size. The cost-to-benefits ratio (unit-price) was therefore not equated across the different FR components. The current study examined the effects of repeated administration of cocaine to pigeons when unit-price under FR schedules was either the same or different. Additionally, the role of a chronic variable-dosing versus chronic fixed-dosing procedure was examined when unit-price was equated across different ratio values. Pigeons were trained to key peck in daily sessions under a three-component multiple FR schedule of food presentation, according to which either 10, 30, or 100 pecks were required for each delivery of food. In Experiment 1, completion of the FR 10, FR 30, and FR 100 resulted in 1.5, 4.5, and 15.0 s access to food, respectively. That is, the response requirement was correlated with access to food time so that unit-price (pecks per second of access to food) was equated across components. After assessing acute effects of a range of doses of cocaine, drug administration occurred daily before each session, with the dose varying from day to day. Tolerance, the magnitude of which was unrelated to the peck requirement, developed under the repeated-dosing regimen. In order to assess whether having equal unit-price was responsible for producing similar levels of tolerance across components, daily drug administration continued in Experiment 2 using the variable-dose regimen, but the amount of food presented each time was fixed at 4.5 s access to food, yielding different unit-prices under the three pecking requirements. Subsequently, the conditions of Experiment 1 were reinstated, i.e., unit-price was equated. Making unit-price different or the same had little influence on effects of cocaine. In Experiment 3, a fixed dose of cocaine was administered before each session while programmed unit-price remained the same across components. Under these conditions, tolerance became peck-requirement related. Specifically, tolerance was most prevalent under the smaller requirements and less robust or absent when the largest requirement was in effect. Differences in unit-price, therefore, were not related to degree of tolerance, but work requirement was. Differences in effects of cocaine across responses requirements, however, were observed only when each session was preceded by the same dose, not when dose varied from session to session.

Animals↗

PubMed2004

Tolerance to response-disruptive effects of cocaine is facilitated by opportunity to respond in the absence of drug.

A dose of cocaine that was 1/8 of a logarithmic unit larger than the smallest dose that produced complete suppression of responding of pigeons under a fixed-ratio 20 schedule was administered prior to 50 daily sessions. If responding occurred, then the dose was increased by 1/8 of a logarithmic unit and administered for an additional 50 sessions. The pigeons were divided into either a 'control' or 'saline' group. Control group pigeons received the same dose of cocaine for 100 additional days. Pigeons in the saline group were also exposed to a daily dosing regimen for 100 more sessions except that saline was substituted once every 5 days. Daily dosing then continued and dose-response functions were re-determined by substituting other doses for the daily dose every fifth session. During the first exposure to each dose, tolerance was evident for five of six pigeons in the saline group, whereas sensitization was evident for pigeons in the control group. Tolerance was observed in both groups following subsequent exposures. Tolerance to effects of behaviorally large doses of cocaine was therefore promoted when saline was occasionally substituted for the daily dose. Opportunity to respond during an ongoing regimen of daily cocaine administration enhanced the development of tolerance.

Animals↗

PubMed2004

Repeated post- or presession cocaine administration: roles of dose and fixed-ratio schedule.

Effects of repeated administration of cocaine to animals behaving under operant contingencies have depended on when the drug is given. Moderate doses given presession have generally led to a decrease in the drug's effect, an outcome usually referred to as tolerance. When these same doses have been given after sessions, the usual result has been no change or an increase in the drug's effects, with the latter usually referred to as sensitization. In the present study, repeated postsession administration of a relatively small dose of cocaine (3.0 or 5.6 mg/kg) to pigeons responding under a multiple fixed-ratio 5, fixed-ratio 100 schedule of food presentation generally resulted in tolerance to the rate-decreasing effects of the drug. When the same dose was given before sessions, little additional tolerance was observed, although some subjects showed further tolerance in the small-ratio component. A regimen of repeated postsession injection of larger (10.0-23.0 mg/kg) doses suppressed key pecking during the session; responding resumed following discontinuation of postsession administrations. Effects of postsession administration of cocaine, therefore, depended on the dose, with smaller doses leading to tolerance and larger ones to suppression of behavior during the session. Effects of postsession drug administration of either small or large doses were not related to whether effects of postsession drug were experienced mainly in the operant test chamber or in the pigeon's home cage. The results with large postsession doses are compatible with a view that the drug acted as a Pavlovian unconditional stimulus, with the session-related stimuli acting as a long-duration Pavlovian conditional stimulus. Tolerance following postsession administration of the smaller doses challenges the view that it depended on experiencing the drug's effects while the arranged reinforcement contingencies were in effect.

Animals↗

PubMed2004

Effects of cocaine on performance under fixed-interval schedules with a small tandem ratio requirement.

Daily administration of cocaine often results in the development of tolerance to its effects on responding maintained by fixed-ratio schedules. Such effects have been observed to be greater when the ratio value is small, whereas less or no tolerance has been observed at large ratio values. Similar schedule-parameter-dependent tolerance, however, has not been observed with fixed-interval schedules arranging comparable interreinforcement intervals. This experiment examined the possibility that differences in rate and temporal patterning between the two types of schedule are responsible for the differences in observed patterns of tolerance. Five pigeons were trained to key peck on a three-component multiple (tandem fixed-interval fixed-ratio) schedule. The interval values were 10, 30, and 120 s; the tandem ratio was held constant at five responses. Performance appeared more like that observed under fixed-ratio schedules than fixed-interval schedules. Effects of various doses of cocaine given weekly were then determined for each pigeon. A dose that reduced responding was administered prior to each session for 50 days. A reassessment of effects of the range of doses revealed tolerance. The degree of tolerance was similar across components of the multiple schedule. Next, the saline vehicle was administered prior to each session for 50 days to assess the persistence of tolerance. Tolerance diminished in all subjects. Overall, the results suggested that schedule-parameter-dependent tolerance does not depend on the temporal pattern of responding engendered by fixed-ratio schedules.

Animals↗

PubMed2003

Sensitization to cocaine in pigeons: interaction with an operant contingency.

A 2-part study with pigeons investigated the role of an explicit operant contingency in determining how cocaine interacts with locomotor activity. In Part 1, pigeons pecked on a fixed-ratio-20 schedule of food presentation. In Part 2, different pigeons were studied without opportunity to peck for food. After determination of cocaine's initial effects, pigeons were exposed to daily administrations of a locomotion-increasing dose of cocaine. Locomotor sensitization was evident in the pigeons of Part 2, and tolerance developed to cocaine's effects on key pecking in the pigeons of Part 1. Locomotor sensitization was generally not evident in the pigeons of Part 1. These results suggest that explicitly conditioned operant behavior may compete with behavior sensitized by prolonged exposure to cocaine.

Animals↗

PubMed2002

Role of dose order in the development of tolerance to effects of cocaine on schedule-controlled behavior in pigeons.

RATIONALE: Tolerance to behavioral effects of cocaine can be produced by exposure to varying doses. The degree to which tolerance develops may depend on dose order. OBJECTIVE: To investigate the relationships between three sequences of doses of cocaine in a daily, variable-dosing regimen and the development of tolerance to effects on schedule-controlled behavior. METHODS: Twelve pigeons responded daily under a fixed-ratio 20 schedule of reinforcement, and performance was investigated under a range of doses of cocaine (0.3-10.0 mg/kg, i.m.) by administering the drug once every 7 days (acute effects). After determination of acute effects of cocaine, the drug was administered daily with dose varying from day to day. Dose order varied systematically across three groups of four pigeons; doses were delivered in ascending, descending, or "sawtooth" (ascending then descending) sequences. This variable-dosing regimen continued until drug effects were stable (at least 13 cycles through all doses). RESULTS: During the acute-dosing regimen, response rates following small cocaine doses were similar to those under control conditions; following moderate-to-high doses, responding was diminished relative to control rates. During the variable-dosing regimen, tolerance to the rate-decreasing effects of cocaine was observed in all groups, regardless of the order in which the drug was delivered, and the magnitude of tolerance was similar across groups. Systematic differences in the rate of recovery from initial response decrements were observed across groups, with rate of recovery fastest under the ascending sequence. CONCLUSIONS: These results suggest that dose order under a variable-dosing regimen does not significantly affect the final attainment of tolerance, although it may contribute to the speed with which tolerance develops.

Animals↗

PubMed1993

Editorial.

Explore the source record for details and available documents.

Journal Article↗