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Biomedical subjects

J E Barrett

Publications and source records attributed to J E Barrett.

At least 145 records · Page 8Linked to original sources
PubMed1979

Two Bass Scale factors and response to placebo and anxiolytic drugs.

Two principal oblique factors are identified in the Bass Social Acquiescence Scale, a measure previously shown to correlate positively with placebo response and negatively with anxiolytic drug response. The two factors appeared very similar in separate analyses of data from samples of 941 psychiatric outpatients and 1,837 college students. Also, results are presented which indicate that one factor, tentatively labeled "traditionalism", accounted for the empirically observed relationships to placebo and drug response in two clinical trials.

Anti-Anxiety Agents↗
PubMed1979

Stroke rehabilitation: analysis of repeated Barthel index measures.

Functional abilities of stroke patients in a rehabilitation hospital are recorded every 2 weeks using the Barthel index. For purposes of this study, data were collected retrospectively and prospectively from consecutive records according to predetermined criteria on forms coded for computer analysis. Total scores of 110 patients were correlated with length of stay, placement at discharge and scores in individual functional abilities. Analysis of the data reveals that an initial score over 40 on the Barthel index defines a population with a greater proportion of discharges to home and that patients with initial scores over 60 have a shorter length of stay. Further analysis indicates a predictable progression in the development of functional skills in this population so that with a Barthel score below 40, no one was independent in the mobility skills and fewer than 50% were independent in the very basic skills, such as feeding, grooming and sphincter control. A score of 60 appears to be a pivotal score where patients move from dependency to assisted independence.

Activities of Daily Living↗
PubMed1978

Ethanol, pentobarbital, and chlordiazepoxide effects in squirrel monkeys responding under fixed-ratio food presentation and stimulus-shock termination schedules.

Ethanol, pentobarbital, and chlordiazepoxide were administered to squirrel monkeys responding under a multiple schedule comprised of two fixed-ratio 100-response schedules (FR 100). Under one FR schedule, the one-hundredth response produced food. Under the other schedule, the one-hundredth response terminated the prevailing stimuli and accompanying schedule of electric shock presentation (stimulus-shock termination). Comparable high response rates were maintained under the two schedules. Each drug produced dose-related decreases in response rates. With all three drugs the effects on all aspects of performance were quantitatively similar for both stimulus-shock termination and food-maintained responding.

Animals↗
PubMed1978

Effects of d-amphetamine and ethanol on responding of squirrel monkeys maintained under fixed-ratio schedules of food presentation and stimulus-shock termination.

Effects of d-amphetamine and ethanol were assessed on comparable behaviors maintained under fixed-ratio schedules of either food presentation or termination of electric shock and an accompanying visual stimulus. Ethanol affected the behaviors similarly in all important aspects; d-amphetamine increased rates of responding maintained by stimulus-shock termination at doses that did not affect rates of food-maintained responding. The increases in responding maintained by stimulus-shock termination were not solely due to decreases in the pause prior to the initiation of responding.

Animals↗
PubMed1978

Behavior simultaneously maintained by both presentation and termination of noxious stimuli.

Lever pressing by two squirrel monkeys was maintained under a 3-minute variable-interval schedule of response-produced electric-shock presentation. At the same time, responding on a second lever was maintained under a 3-minute fixed-interval schedule of termination of the shock-presentation schedule and shock-correlated stimuli. Under the termination schedule, the first response after a 3-minute period produced a 1-minute timeout, during which no events occurred and responding had no scheduled consequence. Relatively high and constant rates of responding were maintained on the lever where responding produced shock. Lower rates and positively accelerated patterns of responding occurred on the lever where responding terminated the shock schedule. Thus, responding was simultaneously maintained by presentation of an event and by termination of a stimulus associated with that event. Rates and patterns of responding on each lever were reversed when the schedules arranged on each lever were reversed on two occasions. When shock intensity was increased from 0 to 10 mA, responding maintained both by presentation of shock and by termination of the shock schedule increased, but responding maintained by shock presentation increased to a greater extent. Positive and negative reinforcement, usually regarded as separate behavioral processes involving different events, can coexist when behavior is controlled by different contingencies involving the same event.

Journal Article↗
PubMed1978

Effects of ethanol on behavior under fixed-ratio, fixed-interval, and multiple fixed-ratio fixed-interval schedules in the pigeon.

Behavior of pigeons was controlled by fixed-ratio, fixed-interval and multiple fixed-ratio fixed-interval schedules of reinforcement. When each thirtieth peck on a response key produced food (fixed-ratio schedule) high rates of responding were maintained; low to intermediate doses of ethanol left unchanged or increased those rates. Under the fixed-interval schedule the first response after 5 min produced food and comparatively lower rates of responding were maintained that gradually increased up to food presentation. Low to intermediate doses of ethanol only decreased overall rates of responding under the fixed-interval schedule. When the fixed-ratio and fixed-interval schedules alternated regularly throughout a single experimental session (multiple fixed-ratio fixed-interval schedule), differential effects that depended upon the schedule of reinforcement were still obtained. Ethanol affected local rates of responding within the fixed intervals differently depending upon the rates prior to drug administration; low rates were increased while higher rates were decreased. As with other drugs, the effects of ethanol on schedule-controlled responding depended upon the particular rates and patterns of responding maintained by the schedule of reinforcement.

Animals↗
PubMed1977

Effects of d-amphetamine on responding simultaneously maintained and punished by presentation of electric shock.

Responding of two squirrel monkeys with a previous avoidance history was developed and maintained under a multiple fixed-interval 10-min schedule of food and electric shock presentation. Under this schedule the first response after 10 min produced either food or shock depending on the prevailing stimulus condition. Subsequently, responding maintained by food was suppressed when each 30th response produced shock (punishment). Presentation of the same intensity electric shock (10 mA) under the fixed-interval schedule in the other component continued to maintain high positively-accelerated rates of responding. Although increases in punished responding do not usually occur with d-amphetamine, under these conditions, where responding was both maintained and suppressed by the same consequent event, d-amphetamine markedly increased punished responding. Responding maintained by the presentation of shock was also increased by d-amphetamine. The effects of d-amphetamine on punished responding can depend on specific features of the situation in which behavior is studied.

Animals↗
PubMed1977

Behavioral history as a determinant of the effects of d-amphetamine on punished behavior.

Food-maintained responding by four squirrel monkeys (Saimiri sciureus) was suppressed by the presentation of electric shock (punishment). Two of these monkeys were experimentally naive and two had a history of responding maintained by both shock-postponement and shock-presentation schedules. In accord with earlier studies, d-amphetamine did not increase punished responding by naive monkeys. However, it did increase punished responding in the others. Subsequently, d-amphetamine also increased punished responding by the initially naive monkeys after they were trained under a shock-postponement schedule. Even though not evident in current behavior, an organism's prior experience can influence the behavioral effects of drugs.

Animals↗
PubMed1977

Effects of d-amphetamine, chlordiazepoxide and promazine on responding of squirrel monkeys maintained under fixed-interval schedules of food presentation and stimulus-shock termination.

Responding of two squirrel monkeys was maintained under a multiple 5-min fixed-interval schedule of food presentation and termination of a stimulus in the presence of which shocks occurred. Under the stimulus-shock termination schedule, shocks occurred independently of responding, on the average of every three minutes; a response after 5 min terminated the prevailing stimulus and shock-presentation schedule. Response rates and patterns of responding under both schedules were comparable although they differed slightly between monkeys. d-Amphetamine increased and promazine decreased responding under both fixed-interval schedules. Chlordiazepoxide increased responding maintained by food presentation but decreased responding maintained by termination of the stimulus-shock complex. Under certain conditions and with certain drugs, the event that maintains responding can determine the effects a drug will have on behavior.

Animals↗
PubMed1976

Effects of alcohol on punished and unpunished responding of squirrel monkeys.

Lever pressing of two squirrel monkeys was maintained initially under a multiple 5 min fixed-interval 5 min fixed-interval schedule of food presentation where, in each of 2 separate stimulus conditions, the first response after 5 min elapsed produced food. Subsequently, during one of the fixed-interval components responding was punished by the presentat of a 5 mA electric shock following each 30th response; rates of responding were markedly suppressed during this component. Unpunshed response rates occurring during the alternate fixed-interval component remained unchanged for one monkey and decreased for the other. Alcohol (1.0-3.0g/kg) increased overall punished rates of responding and decreased unpunished response rates; at higher doses (3.5-4.0 g/kg) all responding was decreased. Where lower local rates of both punished and unpunished responding were comparable, as measured in successive quarters of the fixed-interval, these rates were increased equivalently with alcohol. Comparable higher local rates of punished and unpunished responding were both decreased to about the same extent. The effects of alcohol were determined by the control rate at which behavior occurred, irrespective of whether responding was punished or unpunished.

Alcohols↗
PubMed1976

Interaction of d-amphetamine with pentobarbital and chlordiazepoxide: effects on punished and unpunished behavior of pigeons.

Key pecking of two pigeons was maintained under a multiple schedule of food presentation. In the presence of one keylight stimulus responding produced food according to a fixed-interval 5-min schedule. Additionally, during this component, each 50th response produced electric shock. When a different keylight stimulus was present, key pecking resulted in food delivery under a variable-interval 3-min schedule. Responding was suppressed by shock presentation (punishment) but was still positively accelerated throughout each fixed-interval cycle; steady response rates occurred during the alternate component when only the variable-interval schedule was in effect. Overall rates of punished responding were largely unchanged with d-amphetamine (0.1-3.0 mg/kg); unpunished responding was generally either increased slightly or was decreased. Pentobarbital and chlordiazepoxide (1.0-17.0 mg/kg) administered alone increased both punished and unpunished responding at most doses. Combinations of d-amphetamine with either pentobarbital or chlordiazepoxide produced increases in punished responding that exceeded those obtained with either of these drugs alone. The combined effects of d-amphetamine and either pentobarbital or chlordiazepoxide on unpunished responding depended on the individual dose combinations. Combinations of d-amphetamine with pentobarbital or chlordiazepoxide produced effects on both punished and unpunished responding that differed substantially from those obtained when any of these drugs were administered separately.

Animals↗
PubMed1976

Effect of chlordiazepoxide on schedule-controlled responding and schedule-induced drinking.

Lever pressing of four rats was maintained under a multiple fixed ratio 80, fixed interval 2-min schedule of food presentation. Water was concurrently available from a drinking tube. Overall rates of lever pressing were highest under the fixed ratio schedule and, for three rats, most drinking occurred during the pause preceding responding under the fixed interval schedule. Chlordiazepoxide increased the lower rates of lever pressing maintained under the fixed interval schedule but generally decreased the higher response rates under the fixed ratio schedule. The effects of chlordiazepoxide on schedule-induced licking also depended on the extent to which this response occurred in each schedule component. Typically chlordiazepoxide produced relatively greater increases in the lower levels of licking and either increased less or decreased licking in that component where, under control conditions, this response was more extensive. Chlordiazepoxide also produced overall increases in the total amount of water consumed during the session. When the number of food pellets obtained during the experimental session was given all at one time in the home cage, the amount of water ingested over a period of time equivalent to the session duration was substantially less than that consumed during the experimental session. Chlordiazepoxide did not increase home cage water consumption under this condition.

Animals↗
PubMed1976

Effects of pentobarbital on punished behavior at different shock intensities.

Key-pecking by two pigeons was maintained initially under a schedule where the first response after five minutes had elapsed produced food. When every 50th response produced shock, responding was suppressed (punishment). Although rates and patterns of punished responding remained comparable when the shock intensity was reduced by half, pentobarbital produced much greater increases in both overall and local rates of responding at the lower shock intensity. Pentobarbital also produced larger increases in the low rates of responding immedicately following shock when the lower intensity shock was in effect.

Animals↗
PubMed1976

Conjunctive schedules of reinforcement: III. A fixed-interval adjusting fixed-ratio schedule.

Key pecking of three pigeons was studied under a conjunctive schedule that specified both a fixed-interval and an adjusting fixed-ratio requirement. The fixed-interval schedule was 6 min for one pigeon and 3 min for the other two. The size of the ratio requirement was determined within each cycle of the fixed interval by the duration of the pause before responding began. The fixed-ratio value was at maximum at the start of each fixed interval and decreased linearly until the first response occurred (adjusting fixed-ratio schedule). A peck produced food when the number of responses remaining on the fixed-ratio schedule was completed and when the fixed interval had elapsed. If no response occurred during the interval, the fixed-ratio requirement decreased to one and a single response after the interval elapsed produced food. The initial value of the adjusting fixed-ratio schedule was studied over a range of 0 to 900. Increases in the adjusting fixed-ratio schedule to about 300 responses increased both pause duration and running response rate and also modified the pattern of responding from that obtained under the fixed-interval schedule. Higher values of the adjusting fixed ratio generally decreased pause duration and running response rate and also disrupted responding. Interreinforcement time under the conjunctive schedule was increased substantially when the adjusting fixed-ratio size exceeded 300 responses.

Journal Article↗