On the Use of the Squirrel Monkey in Behavioral and Pharmacological Experiments

Key pressing by squirrel monkeys was maintained under second-order schedules of either intramuscular cocaine injection or food presentation. Under one schedule, each completion of a 10-response fixed-ratio unit produced a brief visual stimulus; the first fixed-ratio unit completed after 30 minutes elapsed produced the stimulus paired with either cocaine injection or food presentation. Generally, short pauses followed by high rates of responding were maintained within the fixed-ratio units, and responding was positively accelerated over the 30-minute interval. Under another schedule, each completion of a 3-minute fixed-interval unit produced the brief stimulus; completion of the 10th fixed-interval unit produced the stimulus paired with either cocaine injection or food presentation. Rates of responding increased within the fixed-interval units, and to a greater extent over the entire 10 fixed-interval units. Patterns of responding depended more on the schedule of reinforcement than on whether cocaine or food maintained responding. Omitting the brief stimuli following all but the last fixed-ratio or fixed-interval units decreased average rates and altered the patterns of responding. Substituting a visual stimulus that was never paired with cocaine or food following all but the last fixed-ratio or fixed-interval units decreased response rates to a lesser extent and did not substantially alter patterns of responding. When the duration of the paired stimulus was varied from .3 to 30.0 seconds, the highest response rates occurred at intermediate durations (1.0 to 10.0 seconds). The manner in which the stimulus changes affected performances depended more on the schedule of reinforcement than on whether cocaine injection or food presentation maintained responding.

Section: Subjectsmentioning

confidence: 99%

A Comparison of Responding Maintained Under Second‐order Schedules of Intramuscular Cocaine Injection or Food Presentation in Squirrel Monkeys

Katz

1979

“…The monkeys were housed individually, and were handled according to the general procedures reported by Kelleher, Riddle, and Cook (1963).…”

Section: Subjects and Apparatusmentioning

confidence: 99%

RESPONDING UNDER FIXED‐RATIO AND MULTIPLE FIXED‐INTERVAL FIXED‐RATIO SCHEDULES OF ELECTRIC SHOCK PRESENTATION¹

McKearney

1970

Squirrel monkeys, initially trained under a schedule of electric shock postponement and then under fixed-interval schedules of electric shock presentation, were studied under multiple fixed-interval fixed-ratio and under fixed-ratio schedules of shock presentation. Under the fixed-interval (10-min) component of the multiple schedule, a pause was followed by a gradual increase in responding to a rate maintained until shock presentation; under the fixed-ratio (3-, 10-, or 30-response) component of the multiple schedule, a brief pause was typically followed by a relatively high and uniform rate of responding until shock was presented. When the 60-sec timeout periods, which usually followed shock presentation, were eliminated from the multiple schedule for one monkey, responding was only transiently affected. In the one monke.y studied, responding was maintained under a fixed-ratio schedule alone (with timeout periods), but rates of responding wcre lower than under the fixed-ratio component of the multiple schedule. Characteristic patterns of responding, similar to those engendered under schedules of food presentation or shock termination, can be maintained under fixed-ratio schedules of shock presentation; further, patterns of responding can be controlled by discriminative stimuli in multiple schedules.Previous experiments (McKearney, 1968(McKearney, , 1969 have shown that, in monkeys previously trained to respond under a schedule of shock postponement, the presentation of responsedependent electric shock under a fixed-interval schedule can enhance responding, and lead to the development and maintenance of a pattern of positively accelerated responding. At the parameter values studied, performances engendered under fixed-interval schedules of shock presentation were similar to those engendered under similar schedules of food presentation or shock termination, (a) in the characteristic pattern of positively accelerated responding engendered, (b) in the effects of elimination, reinstatement, and variations in intensity of the stimulus maintaining the behavior, and (c) in the effects of variations in the parameter value of the fixed-interval schedule (McKearney, 1969).

“…Performances under fixed-interval schedules are of interest because patterns of responding characteristic of suclh schedules have been maintained under various conditions by diverse events, including presentations of brief stimuli associated with occasional presentation of food or electric shock (Byrd, 1972;Byrd and Marr, 1969;Kelleher, 1966a, b;Kelleher and Morse, 1968). Preliminary results indicate that patterns of responding characteristic of fixed-interval schedules can be miaintained in the squirrel monkey by the presentationi of a brief visual stimulus under a second-order schedule of cocaine injection (Goldberg, Kelleher, and Morse, 1975 Kelleher, Gill, Riddle, and Cook (1963). Two of these monkeys (S-467 and S-474) had been used in previous studies of cocaine self-administration (Goldberg and Kelleher, 1976 The basic second-order schedule was a fixed ratio (FR) of fixed-interval (FI) components (Kelleher, 1966a, b).…”

mentioning

confidence: 93%

FIXED‐INTERVAL RESPONDING UNDER SECOND‐ORDER SCHEDULES OF FOOD PRESENTATION OR COCAINE INJECTION¹

Kelleher

Goldberg

1977

Squirrel monkeys operated a key under second-order schedules in which every tenth completion of a 5-minute fixed interval resulted in either presentation of food or intravenous injection of cocaine. When a 2-second light was presented at the completion of the component fixed-interval schedules, positively accelerated responding developed and was nmaintained in each component. Over a tenfold range of doses of cocaine (30 to 300 tg/kg/injection) and amounts of food (0.75 to 7.5 g/presentation), the secondorder schedule of cocaine injection maintained higher average rates of responding than the second-order schedule of food presentation. Substituting saline for cocaine or eliminiating food presentations decreased average rates of responding. When no stimulus change occurred at the completion of the first nine component fixed-interval schedules, but the 2-second light and food presentation or cocaine injection still occurred after the tenth component, only low and relatively constant rates of responding were maintained in each component. Patterns of responding characteristic of 5-minute fixed-interval schedules were maintained by the 2-second light paired with either cocaine injection or food presentation, though the maximum frequency of cocaine injection or food presentation was less than once per 50 minutes. Key words: cocaine, self-administration, second-order schedules, fixed interval schedules, key pressing, squirrel monkey The control of behavior by environmental stimuli that are intermittently associated with drug injections can be studied systematically with second-order schedules of drug injections. This type of higher-order schedule treats a pattern of behavior controlled by a schedule (tlhe first-order or component schedule) as a response that can itself be controlled by a schedule (the second-order schedule). When a brief visual stimulus is presented at the completion of each component schedule, secondorder schedules of drug injection can maintain orderly sequences of responding even when injections occur infrequently.