Drug Discrimination: Historical Origins, Important Concepts, and Principles.

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.

Measurement of the lowest dosage of phenobarbital that can produce drug discrimination in rats.

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 high-sensitivity drinkometer circuit with 60-Hz filtering.

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.

Injection pain of prilocaine plain, mepivacaine plain, articaine with epinephrine, and lidocaine with epinephrine.

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.

Prevalence of cusp fractures in teeth restored with amalgam and with resin-based composite.

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.