RESUMEN
Research on the stimulus properties of drugs began with studies on state dependent learning during the first half of the twentieth century. From that research, an entirely new approach evolved called drug discrimination. Animals (including humans) could discriminate the presence or absence of a drug; once learned, the drug could serve as a discriminative stimulus, signaling the availability or nonavailability of reinforcement. Early drug discrimination research involved the use of a T-maze task, which evolved in the 1970s into a two-lever operant drug discrimination task that is still used today. A number of important concepts and principles of drug discrimination are discussed. (1) The discriminative stimulus properties of drugs are believed in large part to reflect the subjective effects of drugs. While it has been impossible to directly measure subjective effects in nonhuman animals, drug discrimination studies in human subjects have generally supported the belief that discriminative stimulus properties of drugs in nonhuman animals correlate highly with subjective effects of drugs in humans. In addition to the ability of the drug discrimination procedure to measure the subjective effects of drugs, it has a number of other strengths that help make it a valuable preclinical assay. (2) Drug discrimination can be used for classification of drugs based on shared discriminative stimulus properties. (3) The phenomena of tolerance and cross-tolerance can be studied with drug discrimination. (4) Discriminative stimulus properties of drugs typically have been found to be stereospecific, if a drug is comprised of enantiomers. (5) Discriminative stimulus properties of drugs reflect specific CNS activity at neurotransmitter receptors. (6) Both human and nonhuman subjects display individual differences in their sensitivity to discriminative stimuli and drugs. (7) The drug discrimination procedure has been used extensively as a preclinical assay in drug development. This chapter is the first in the volume The Behavioural Neuroscience of Drug Discrimination, which includes chapters concerning the discriminative stimulus properties of various classes of psychoactive drugs as well as sections on the applications and approaches for using this procedure.
Asunto(s)
Discriminación en Psicología , Psicotrópicos/farmacología , Animales , Condicionamiento Operante/efectos de los fármacos , Humanos , Aprendizaje , PsicofarmacologíaRESUMEN
RATIONALE: Accurate measurement of the threshold dosage of phenobarbital that can produce drug discrimination (DD) may improve our understanding of the mechanisms and properties of such discrimination. OBJECTIVES: This study aimed to compare three methods for determining the threshold dosage for phenobarbital (D) versus no-drug (N) DD. MATERIALS AND METHODS: Rats learned a D versus N DD in two-lever operant training chambers. A titration scheme was employed to increase or decrease dosage at the end of each 18-day block of sessions depending on whether the rat had achieved criterion accuracy during the sessions just completed. Three criterion rules were employed, all based on average percent drug lever responses during initial links of the last six D and six N sessions of a block. The criteria were: D% > 66 and N% < 33; D% > 50, and N% < 50; (D% - N%) > 33. Two squads of rats were trained, one immediately after the other. RESULTS: All rats discriminated drug versus no drug. In most rats, dosage decreased to low levels and then oscillated near the minimum level required to maintain criterion performance. The lowest discriminated dosage significantly differed under the three criterion rules. The squad that was trained second may have benefited by partially duplicating the lever choices of the previous squad. CONCLUSIONS: The lowest discriminated dosage is influenced by the criterion of discriminative control that is employed and is higher than the absolute threshold at which discrimination entirely disappears. Threshold estimations closer to absolute threshold can be obtained when criteria are employed that are more permissive of errors and that allow rats to maintain lever preferences.
Asunto(s)
Discriminación en Psicología/efectos de los fármacos , Fenobarbital/administración & dosificación , Fenobarbital/farmacología , Animales , Condicionamiento Operante/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Masculino , Psicofarmacología , Ratas , Ratas Long-Evans , Detección de Señal Psicológica/efectos de los fármacosRESUMEN
This article describes a drinkometer circuit designed to (1) detect licks even if the resistance of the skin on the animal's feet becomes quite high due to low humidity, (2) automatically adjust its triggering threshold and increase its gain so that it will continue to detect licks when the water delivery spout is partially shorted to ground by high ambient humidity, (3) reject 60-Hz signals so they will not be treated as rapid licks by the data-recording system, and (4) tolerate the high voltages that can occur if the subject receives an electric shock while drinking. This lickometer will be especially useful in situations where it is not practical to monitor for possible signal failure due to high or low humidity, or where 60-Hz artifacts may contaminate the signal provided to a recording computer.
Asunto(s)
Psicología/métodos , Psicología/estadística & datos numéricos , HumanosRESUMEN
In a double-blind study design, 1,391 consecutive patients in a general dental practice received one of four different local anesthetics (articaine with epinephrine, lidocaine with epinephrine, mepivacaine plain, or prilocaine plain) via a maxillary buccal infiltration, palatal infiltration, or inferior alveolar block injection. The anesthetics were administered under clinical conditions by one of two dentists. Immediately after receiving the injection, patients rated the pain from each injection on a ten-point scale. The pain response was analyzed according to the dentist administering the injection, the location of injection, the patient's gender, and the type of anesthetic administered. Injection of prilocaine plain produced significantly lower pain scores than lidocaine with epinephrine, mepivacaine plain, or articaine with epinephrine.
Asunto(s)
Anestésicos Locales/administración & dosificación , Dolor/etiología , Anestésicos Locales/efectos adversos , Carticaína/administración & dosificación , Carticaína/efectos adversos , Método Doble Ciego , Epinefrina/administración & dosificación , Epinefrina/efectos adversos , Femenino , Humanos , Inyecciones/efectos adversos , Inyecciones/instrumentación , Lidocaína/administración & dosificación , Lidocaína/efectos adversos , Masculino , Nervio Mandibular , Mepivacaína/administración & dosificación , Mepivacaína/efectos adversos , Mucosa Bucal , Agujas , Bloqueo Nervioso/efectos adversos , Dimensión del Dolor , Hueso Paladar , Prilocaína/administración & dosificación , Prilocaína/efectos adversos , Factores Sexuales , Vasoconstrictores/administración & dosificación , Vasoconstrictores/efectos adversosRESUMEN
BACKGROUND: Complete cusp fracture in restored teeth is a common problem observed in general dental practice. Many dentists believe that teeth restored with amalgam are more likely to be associated with cusp fractures than are those restored with resin-based composite. METHODS. The authors noted the condition of 10,869 posterior teeth with amalgam or resin-based composite restorations with at least one cusp present, unrestored or missing in 1,902 consecutively seen adult patients in a private general dental practice. For each patient, the authors recorded age, type of restorations, number of surfaces of each restoration, and presence or absence of a complete cusp fracture and of caries. RESULTS: There was a lower percentage of cusp fractures in younger subjects than in older subjects and in teeth with a single restored surface than in those with more than one restored surface. There was no significant difference in the prevalence of cusp fracture rates in amalgam-restored teeth versus composite-restored teeth in subjects aged 18 through 54 years. In subjects aged 55 through 96 years, there was a marginally significantly greater cusp fracture rate in composite-restored teeth than in those restored with amalgam. Overall, there was no significant difference in the prevalence of cusp fracture in teeth restored with amalgam (1.88 percent) versus composite-restored teeth (2.29 percent). CONCLUSIONS: The prevalence of cusp fractures in amalgam-restored teeth and resin-based composite-restored teeth is not significantly different. Teeth with more than one surface restored with either resin-based composite or amalgam and teeth in older subjects were more likely to suffer a cusp fracture. CLINICAL IMPLICATIONS: Teeth restored with amalgam and with resin-based composite exhibited equally low cusp fracture prevalence. When choosing between amalgam and resin-based composite in consideration of the likelihood of a future cusp fracture, either restorative material is acceptable.
Asunto(s)
Restauración Dental Permanente/efectos adversos , Fracturas de los Dientes/etiología , Adolescente , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Resinas Compuestas/efectos adversos , Amalgama Dental/efectos adversos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Corona del Diente/lesionesRESUMEN
BACKGROUND: Prilocaine plain has been described in the literature as causing less pain on injection than bupivacaine with epinephrine, possibly because of the higher pH of the prilocaine anesthetic solution. METHODS: In a double-blind study design, 681 consecutive patients in a general dental practice received maxillary buccal infiltration, posterior palatal infiltration or inferior alveolar block injections, administered under clinical conditions by one of two dentists. Immediately after injection, patients rated the pain from each injection on a six-point scale. The pain response was analyzed according to treating dentist, location of injection, patient's sex and anesthetic administered. RESULTS: The reported pain on injection of bupivacaine with epinephrine was significantly greater than that of prilocaine plain. Patients reported no significant difference in pain at different injection locations, except that palatal injections caused significantly more reported pain than did anterior maxillary infiltration, posterior maxillary infiltration or inferior alveolar block injections. CONCLUSIONS: Under clinical conditions, the injection of bupivacaine with epinephrine causes significantly more perceived pain than does the injection of prilocaine plain. Clinical Implications. Bupivacaine with epinephrine and prilocaine plain have certain advantages and disadvantages that should be considered before choosing an anesthetic for a dental procedure. A disadvantage of bupivacaine with epinephrine is that it produces more perceived pain than does prilocaine plain.