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Biomedical subjects

T H Kelly

Publications and source records attributed to T H Kelly.

At least 37 records · Page 2Linked to original sources
PubMed1991

The effects of repeated amphetamine exposure on multiple measures of human behavior.

Two groups of three healthy adult male volunteers (n = 6) participated in 15-day residential studies. Each study day was divided into a private work period (1000 to 1630), during which subjects had access to four work tasks, and a social period (1700 to 2330), during which subjects had access to a number of recreational activities available under social or private conditions. Occasionally during the study, access to high-probability activities was made contingent upon participating in low-probability activities. Tobacco cigarettes and food were available throughout each day (0900 to 2330). Each subject received active and placebo d-amphetamine doses (0 or 10 mg/70 kg) twice daily during two, three-consecutive-day intervals. Active and placebo dose intervals were presented in an alternating fashion, with order of exposure counterbalanced between groups. Amphetamine consistently decreased food intake, improved accuracy of performance on some work tasks, and increased verbal interaction and cigarette smoking. No tolerance to these effects was observed. Increases in VAS ratings of dose "potency" and "liking," as well as "stimulated" and "anxious," and decreases in "sedated" were observed during initial amphetamine exposure, but tolerance to these effects developed rapidly. The simultaneous measurement of multiple dimensions of human behavior establishes a profile of amphetamine's effects which is useful for comparison with the behavioral profiles of other drugs, such as marijuana.

Adult↗
PubMed1991

Response patterns and cardiovascular effects during response sequence acquisition by humans.

The effects of temporal delays imposed between successive responses and of vitamin C administration were examined on the acquisition of response sequences and on cardiovascular reactivity during sequence acquisition. Thirteen adult subjects (6 female, 7 male), in good health, gave written consent prior to participating in 12 weekly 45-min sessions. Points, exchanged for money after each session, were presented when subjects completed 15-response sequences on a touch-sensitive three-response keypad. A position counter increased from 0 to 14 as subjects emitted correct responses in the sequence. Four novel 15-response sequences were presented each session. No delays were imposed between successive responses during the acquisition of one sequence; delays were imposed immediately following each response during the acquisition of a second sequence, thereby delaying response feedback; delays were imposed following feedback during acquisition of a third sequence, resulting in the removal of the stimulus correlated with sequence position; and, as a control condition, delays were imposed following feedback, but stimuli correlated with sequence position were reinstated prior to the next response during acquisition of a fourth sequence. Subjects were exposed to one of two delay durations (0.2 and 0.5 or 0.5 and 1.0 s) each session, and delay durations alternated every session. During Weeks 5 to 8, subjects received 3 grams of vitamin C per day, whereas during Weeks 1 to 4 and 9 to 12, subjects received placebo under single-blind conditions. All subjects acquired the sequences, as evidenced by decreasing percentages of incorrect responses across trials. When temporal delays were imposed between successive responses during sequence acquisition, acquisition efficiency was enhanced. Examination of response latencies suggested that the status of preceding responses (i.e., correct or incorrect) rather than the status of the position counter influenced subsequent responding. Cardiovascular effects were inversely related to the length of the temporal delay. Neither cardiovascular reactivity or sequence acquisition were related to vitamin C administration.

Adult↗
PubMed1990

Effects of acute administration of diazepam and d-amphetamine on aggressive and escape responding of normal male subjects.

Normal males participated in sessions providing two operant response options and were administered either diazepam (study I and II) or d-amphetamine (study II). The acute effects of diazepam on human aggressive responding, which ostensibly subtracted points from another person, were determined in study I. Study II was conducted to determine the extent to which social context and response consequence influenced diazepam (study I) and d-amphetamine (previous research) effects on aggressive responding. In study II, the other response option was escape responding which protected the subject's counter from point losses. Aggressive and escape responding were engendered by subtracting points from the subject's counter, and maintained by initiation of intervals free of point loss. Point subtractions were attributed to the other person (study I) or to a machine (study II). Responding to accumulate points exchangeable for money was available in both studies. Acute diazepam administration decreased aggressive responding in most subjects (study I), slightly increased escape responding (study II), and decreased responding to accumulate points. In study II, d-amphetamine increased both escape responding and responding to accumulate points. The effects of d-amphetamine and diazepam were altered by the instructed source of point loss.

Aggression↗
PubMed1990

The effects of d-amphetamine on food intake of humans living in a residential laboratory.

Two groups, each consisting of three normal weight, male research volunteers, lived continuously in a residential laboratory for 15 days. All contact with the experimenters was through a networked computer system and subjects' behaviors, including food intake, were continuously recorded. During the first part of the day, subjects remained in their private rooms doing work activities. During the remainder of the day, they had the option to socialize with each other. A wide variety of food items were continuously available. Subjects controlled their own patterns of food intake, and could consume any item, or number of items, at any time during the day. Beverages containing d-amphetamine (10 mg per 70 kg) or placebo were consumed daily at 0930 and 1630 hrs. Amphetamine significantly reduced total daily caloric intake to about 70% of placebo levels. The reduction in intake was a consequence of a decrease in number of eating occasions per day; no changes in mean intake per occasion were observed. Amphetamine produced similar decreases in the daily number of snack and meal items, and in protein, fat, and carbohydrate intake. These results demonstrate that amphetamine has significant effects on human food intake, and the study of human feeding behavior under similar naturalistic conditions should provide important information about the behavioral actions of drugs affecting food intake.

Adult↗
PubMed1990

Multidimensional behavioral effects of marijuana.

1. Five groups of three healthy adult male volunteers (n = 15), all reporting occasional, controlled marijuana use, gave written consent and participated in residential studies lasting 6 to 15 days. 2. Subjects smoked marijuana cigarettes (0, 1.3, 2.3 or 2.7% THC, w/w) at 0945, 1330, 1700 and 2030 every day, and each subject received both active and placebo marijuana cigarettes in 2-5 consecutive day phases, with placebo and active doses presented in an alternating fashion. 3. In comparison with placebo, active marijuana produced a variety of effects on measures of human behavior, including increases in food consumption and errors on psychomotor tasks, decreases in bouts of tobacco-cigarette smoking and verbal interactions and no changes in rates of task performance, time spent under social conditions or social cooperation. 4. Dimensions of human behavior were differentially sensitive to the effects of smoked marijuana. 5. The simultaneous measurement of multiple dimensions of human behavior is a useful procedure for determining dose potency following marijuana administration.

Adult↗
PubMed1990

Caloric compensation for lunches varying in fat and carbohydrate content by humans in a residential laboratory.

Two groups of three subjects participated in a residential study that assessed the effects of varying the macronutrient and caloric content of a required lunch meal on subsequent food choice and intake. Lunches contained 431 or 844 kcal, with the caloric differential created by manipulating the calories derived from either fat or carbohydrate (CHO). Each lunch condition (high-fat, high-CHO, low-fat, and low-CHO) was examined for 3 consecutive days. Subjects controlled their own patterns of food intake and could consume any item or number of items at any time during the day or night. There were no significant differences in total daily caloric intake across conditions, indicating that subjects compensated for the caloric content of the lunch regardless of the macronutrient content. Total daily caloric intake under the high-fat and high-CHO conditions was 2824 +/- 151 (mean +/- SEM) and 2988 +/- 187 kcal, respectively, whereas intake under the low-fat and low-CHO conditions was 2700 +/- 131 and 2890 +/- 247 kcal, respectively.

Adult↗
PubMed1990

Human aggressive responses maintained by avoidance or escape from point loss.

During 50-min sessions, 6 male human subjects could press either Button A or Button B available as nonreversible options. Button A presses were nonaggressive responses and earned points according to a fixed-ratio 100 schedule. Prior to the experiment subjects were instructed that every 10 (fixed-ratio 10) Button B presses (aggressive responses) subtracted a point from a fictitious 2nd subject. A random-time schedule of point loss was used to engender aggressive responding. The instructions attributed these point losses to the Button B presses of the subject's fictitious partner. Aggressive responding either escaped or avoided point loss by initiating an interval free of point loss. The duration of the interval was varied systematically across sessions. Avoidance contingencies maintained a high rate of aggressive responding over 30 sessions in the absence of point loss. Escape contingencies also maintained aggressive responding across sessions, with rates of aggressive responding corresponding to rates of point loss.

Adult↗
PubMed1990

Motivational effects of smoked marijuana: behavioral contingencies and low-probability activities.

Six adult male research volunteers, in two groups of 3 subjects each, lived in a residential laboratory for 15 days. All contact with the experimenters was through a networked computer system, and subjects' behavior was monitored continuously and recorded. During the first part of each day, they were allowed to socialize. Two cigarettes containing active marijuana (2.7% delta 9-THC) or placebo were smoked during the private work period and the period of access to social activities. Three-day contingency conditions requiring subjects to engage in a low-probability work activity (instrumental activity) in order to earn time that could be spent engaging in a high-probability work activity (contingent activity) were programmed during periods of placebo and active-marijuana smoking. During placebo administration, the contingency requirement reliably increased the amount of time that subjects spent engaged in the low-probability instrumental activity and decreased the time spent engaged in the high-probability activity. During active-marijuana administration, however, the increases in instrumental activity were consistently larger than observed under placebo conditions. The decreases in contingent activity were similar to those seen under placebo conditions. Smoking active marijuana was thus observed to produce increments in instrumental activity under motivational conditions involving contingencies for "work activities."

Adult↗
PubMed1990

Residential laboratory research: a multidimensional evaluation of the effects of drugs on behavior.

The data presented point to the importance of studying drug effects under conditions similar to those in which drugs are taken outside of the laboratory. Interactions between the reinforcing and other direct effects of these drugs, as well as their interactions with ongoing environmental events can only be evaluated under such conditions. These data support the utility of a residential research facility for the investigation of substance use and its effects under conditions which approximate those in which people live outside of the laboratory. This unique laboratory, designed for continuous observation of human behavior over extended periods of time, provides a controlled environment with the flexibility for establishing a range of subject behaviors, and the ability to simultaneously monitor a wide range of individual and social behavior patterns. We can study regulation of drug intake and its effects, both within a day and over days, assessing the effects of experimental manipulations on the patterning of self-administration behavior as well as the performance of a range of other behaviors as a function of drug self-administration. The design of such studies is a logical extension of basic preclinical research, as well as more traditional human behavioral pharmacology research. Although little data are yet available on drug-related "hangovers" or "morning after" effects, it should be clear that this residential laboratory would provide ideal experimental conditions for such research. We have shown that subjects will exhibit stable patterns of drug self-administration which are sensitive to systematic manipulation of variables. Therefore, we are in the position of being able to evaluate longer term effects on performance of drug-taking behavior as it occurs under conditions approximating the natural ecology. The examples of data collected in the laboratory have demonstrated that drug effects are not a unitary phenomenon, but instead depend on ongoing behaviors as well as pharmacological variables such as drug and dose. If we are going to evaluate drugs and the way in which they affect workplace behavior, we must carry out our evaluation under conditions which approximate those in which people might be using them, while at the same time controlling extraneous variables and protecting the participants from possible deleterious effects. We have shown that drugs, such as marijuana and amphetamine, have divergent effects that are influenced by both situational and behavioral factors. A thorough evaluation of the effects of any drug on behavior is, therefore, dependent on the evaluation of the drug's effects under the conditions in which it is likely to be taken.

Adult↗
PubMed1990

Smoked marijuana effects on tobacco cigarette smoking behavior.

The effects of marijuana smoke exposure on several measures of tobacco cigarette smoking behavior were examined. Eight healthy adult male volunteers, who smoked both tobacco and marijuana cigarettes, participated in residential studies, lasting 10 to 15 days, designed to measure the effects of marijuana smoke exposure on a range of behavioral variables. Tobacco cigarettes were available throughout the day (9:00 A.M. until midnight). Each day was divided into a private period (9:00 A.M. to 5:00 P.M.), during which subjects were socially isolated, and a social period (5:00 P.M. to midnight), during which subjects could interact. Under blind conditions, subjects smoked placebo and active marijuana cigarettes (0%, 1.3%, 2.3%, or 2.7% delta 9-tetrahydrocannabinol) four times daily (9:45 A.M., 1:30 P.M., 5:00 P.M. and 8:30 P.M.). Each subject was exposed to both placebo and one active dose over 2- to 5-consecutive-day intervals, and dose conditions (i.e., placebo or active) alternated throughout the study. Active marijuana smoking significantly decreased the number of daily tobacco smoking bouts, increased inter-bout intervals and decreased inter-puff intervals. Marijuana decreased the number of tobacco smoking bouts by delaying the initiation of tobacco cigarette smoking immediately after marijuana smoking, whereas decreases in inter-puff intervals were unrelated to the time of marijuana smoking. No consistent interactions between marijuana effects and social or private periods (i.e., time of day) were observed.

Adult↗
PubMed1989

Effects of nicotine gum and tobacco smoking on human avoidance responding.

Three male smokers were exposed to a free-operant avoidance schedule in which a lever press postponed a point subtraction on a counter for twenty seconds. Subtractions were scheduled to occur every 5 seconds in the absence of lever presses. Prior to each experimental session the subject was administered varying amounts of nicotine via either chewing nicotine gum or smoking low or high nicotine yield cigarettes. Smoking cigarettes resulted in increased avoidance responding relative to baseline nonsmoking rates. Chewing nicotine gum did not produce changes in avoidance responding, however, nicotine blood levels produced by chewing nicotine gum were similar to levels produced by smoking cigarettes. The differential responding determined by route of nicotine administration is discussed and the implications for use of nicotine gum as an adjunct for smoking cessation is addressed.

Avoidance Learning↗
PubMed1989

Motivational effects of smoked marijuana: behavioral contingencies and high-probability recreational activities.

Fifteen adult male research volunteers, in five groups of three subjects each, lived in a residential laboratory for up to 20 days. All contact with the experimenters was through a networked computer system, and subjects' behaviors were monitored continuously and recorded. During the first part of each day, subjects remained in their private rooms doing planned work activities, and during the remainder of each day, they were allowed to socialize. One or two cigarettes containing active marijuana (1.3-2.7% delta 9-THC) or placebo were smoked during both the private work period and the period of access to social activities. Two-or three-day contingency conditions requiring subjects to engage in a low-probability recreational activity in order to earn time that could be spent engaging in a high-probability recreational activity were programmed during periods of placebo and active marijuana smoking. During placebo administration, the contingency requirement reliably increased the amount of time that subjects spent engaged in the low-probability instrumental activity and decreased the time spent engaged in the high-probability contingent activity. During active marijuana administration, however, the increases in instrumental activity were consistently smaller than observed under placebo conditions. The decreases in high-probability contingent activity were similar across drug conditions. Smoking active marijuana was thus observed to produce instrumental decrements under motivational conditions involving recreational contingencies.

Adult↗
PubMed1989

Effects of d-amphetamine on human aggressive responding maintained by avoidance of provocation.

Male subjects were administered placebo and three doses of d-amphetamine (5, 10 and 20 mg per 70 kg of body weight) under double-blind conditions in a laboratory setting which provided both aggressive and nonaggressive response options. the nonaggressive response was button pressing maintained by the presentation of points which were exchanged for money. The aggressive response was pressing another button which ostensibly resulted in the subtraction of points from a fictitious person. Aggressive responding was initiated by subtracting points from the subject. Point subtractions were attributed to the other person. Aggressive responding was maintained by an avoidance contingency between aggressive responses and scheduled provoking point subtraction presentations. d-Amphetamine increased nonaggressive responding, while aggressive responding was increased at the 10 mg dose and 20 mg resulted in significant decreases in aggressive responding relative to the 10 mg dose. Comparisons with previous research indicate that the contingency relationship between aggressive responses and presentation of provoking point subtractions can alter the effects of d-amphetamine on aggressive responding.

Adolescent↗
PubMed1989

Concurrent reinforcement and alcohol: interactive effects on human aggressive behavior.

The relationship between alcohol and human aggressive behavior was studied under conditions in which nonaggressive response requirements maintained by point presentation were manipulated. Six normal adult male recreational alcohol users pressed buttons that produced points (redeemable for money) on their own counters or ostensibly subtracted points (money) from another fictitious subject described as participating in the same study at another location. During random components of each session, subjects were required to press a button 50, 200 or 500 times in order to produce point increments on their own counters. Ten responses on a second button were required to subtract a point from the other subject during all components. Aggressive responding was engendered by occasional point subtractions which were attributed to the fictitious subject. Alcohol (0, 0.125, 0.25 and 0.5 g/kg of 95% ethanol) produced dose-related increases in aggressive responding. Aggressive responding was also significantly related to the concurrent schedule of point presentation. Finally, a significant interaction between alcohol and concurrent point presentation contingencies was observed. These results indicate that aggressive responding is affected by ongoing reinforcement contingencies not directly related to aggressive behavior and that reinforcement schedule interaction may be one factor mediating the situation-dependent nature of alcohol's effects on aggressive behavior.

Adolescent↗
PubMed1988

Effects of provocation and alcohol on human aggressive behavior.

Effects of provoking stimuli on human aggressive behavior and on the relationship between alcohol and aggressive behavior were measured. Four adult males manipulated pushbuttons that produced points on their own counters (redeemable for money) or ostensibly subtracted points (money) from the counters of fictitious persons described as participating in the same study at other locations. During five 10-min components, frequency and intensity of point subtractions, ostensibly controlled by another person, were manipulated. Each subject was repeatedly exposed to alcohol doses (0.25, 0.5 and 0.75 g/kg of 95% ethanol) over time using a repeated measures design. Aggressive responding was affected by provocation intensity and frequency. The highest dose of alcohol produced selective increases in aggressive responding; however, no interactions between alcohol effects and provocation conditions were observed.

Adult↗
PubMed1988

The relationship of stimulus control to the treatment of substance abuse.

This brief review points out important reasons for considering stimulus control in the treatment of substance abuse. Traditional drug abuse treatment procedures appear to manipulate stimulus control factors during treatment whether or not explicitly stated. In addition, treatment procedures differ in the profile of stimulus control dimensions addressed during treatment and can be differentiated in these terms. Assessment of the relative success of various treatments in modifying aspects of the environmental control of drug taking is beyond the scope of this paper, but analysis of dimensions of stimulus that control an individual's drug-seeking behavior may be a critical issue in determining which of the range of available treatment modalities will be most successful.

Behavior Therapy↗
PubMed1987

Effects of d-amphetamine on aggressive responding of normal male subjects.

Male research subjects were administered placebo and three doses of d-amphetamine (5, 10, and 20 mg/70 kg of body weight) under double-blind conditions in a laboratory situation that provided both aggressive and nonaggressive response options. The nonaggressive response was button pressing maintained by the presentation of points which were exchanged for money. The aggressive response was button pressing on a separate manipulandum which ostensibly subtracted points from a fictitious person. Aggressive responding was initially established by subtracting points from the research subjects, which was attributed to the other person. d-Amphetamine increased nonaggressive responding, while aggressive responding was generally decreased.

Adult↗