Effects Of Daily Morphine Administration And Deprivation On Choice And Demand For Remifentanil And Cocaine In Rhesus Monkeys

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/96717/1/jeab.2011.95-75.pd

Resistencia al cambio en programas de evitación y tiempo-fuera de evitación

Galizio (1999) reportó que una respuesta que producía un tiempo fuera dela evitación era más resistente a la extinción que la respuesta de evitación misma. El presente estudio busca extender ese hallazgo. Seis veces durantecada sesión, un programa señalado de razón fija 10 fue impuesto sobre unprograma de eliminación de choque de ciclo variable choque-choque de 60 s.Al completar la razón, las ratas producían un tiempo fuera señalado de 5 u 8minutos. Se compararon las tasas de respuesta mantenidas por la evitacióny el tiempo fuera analizando la respuesta durante cada presentación (tiempofuera) de la RF y en el período previo de 5 min (evitación). La resistencia alcambio fue determinada mediante (a) un incremento el parámetro de ciclovariable de 60 a 120 s (Experimento 1), y (b) una extinción por omisión dechoques (Experimento 2). En ambos casos, la respuesta de tiempo fuera fuemás resistente al cambio que la respuesta de evitación

Assessing Unit‐Price Related Remifentanil Choice In Rhesus Monkeys

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/96725/1/jeab.2006.108.05.pd

Acquisition Of Cocaine Self-Administration With Unsignaled Delayed Reinforcement In Rhesus Monkeys

Six experimentally naive rhesus monkeys produced 0.01 mg/kg/infusion cocaine by lever pressing under a tandem fixed-ratio 1 differential-reinforcement-of-other-behavior schedule. One lever press initiated an unsignaled 15- or 30-s delay culminating in cocaine delivery. Each press made during the delay reset the delay interval. With two exceptions, responding was acquired and maintained at higher rates than responding on a second (inoperative) lever. For the exceptions, a cancellation contingency was arranged in which each formerly inoperative-lever response reset the tandem schedule. This manipulation reduced presses on the inoperative lever. Subsequently, the consequences of responding on the two levers were reversed, and the monkeys again responded at higher rates on the operative lever. As a comparison, 3 additional experimentally naive monkeys received response-independent cocaine deliveries. Although lever pressing was observed, it extinguished and was subsequently reestablished under the tandem schedule. The results suggest that although response-reinforcer contiguity is not required for cocaine to acquire reinforcing functions, a response-reinforcer relation appears necessary

Response Acquisition and Fixed-Ratio Escalation Based on Interresponse Times in Rats

The effectiveness of a fixed-ratio (FR) escalation procedure, developed by Pinkston and Branch (2004) and based on interresponse times (IRTs), was assessed during lever-press acquisition. Forty-nine experimentally naïve adult male Long Evans rats were deprived of food for 24 hr prior to an extended acquisition session. Before the start of the session, three food pellets were placed in the magazine. Otherwise, no magazine training, shaping, nor autoshaping procedure was employed. The first 20 presses each resulted in the delivery of a 45-mg food pellet. Then, the FR increased (2, 4, 8, 11, 16, 20, 25, 30) when each IRT in the ratio was less than 2 s during three consecutive ratios. Sessions lasted 13 hr or until 500 pellets were earned. On average, rats reached a terminal ratio of 11 (mean) or 16 (median) during the first session. Seven rats reached the maximum value of FR 30 and only one rat did not acquire the response. In most rats, a break-and-run pattern of responding characteristic of FR schedules began to develop in this acquisition session. Subsequently, the ratio-escalation procedure continued during daily 2-hr sessions. In these sessions, the starting ratio requirement was set at the terminal ratio reached in the previous session. Using this procedure, over half (26) of the rats reached the FR 30 requirement by the fourth session. These data demonstrate that a ratio-escalation procedure based on IRTs provides a time-efficient way of establishing ratio responding

Behavioral Perspectives on the Neuroscience of Drug Addiction

Neuroscientific approaches to drug addiction traditionally have been based on the premise that addiction is a process that results from brain changes that in turn result from chronic administration of drugs of abuse. An alternative approach views drug addiction as a behavioral disorder in which drugs function as preeminent reinforcers. Although there is a fundamental discrepancy between these two approaches, the emerging neuroscience of reinforcement and choice behavior eventually may shed light on the brain mechanisms involved in excessive drug use. Behavioral scientists could assist in this understanding by devoting more attention to the assessment of differences in the reinforcing strength of drugs and by attempting to develop and validate behavioral models of addiction