A Plexiglas helmet and catheter protection assembly for chronic intravenous administration of drugs in small primates

A restraint and catheter-protection system consisting of a Plexiglas helmet and a nylon-tubing protector line has been developed to permit the long-term study of drug self-administration in monkeys. Frequent observations of monkeys in the system over a period exceeding a year have shown that the technique satisfies the requirements for long-term study of drug administration through an indwelling catheter and avoids several recurring problems inherent in other protection systems. Additional applications of the helmet and protector line are discussed.     

An inherent problem in certain constant-current stimulators

A basic and potentially dangerous problem that may occur in the use of triggered constant-current generators for stimulation is discussed in the general case. A solution with schematic illustration is presented for one specific constant-current generator, the CCS-1A manufactured by Electronics of Life Sciences, Inc.     

The semiautomatic Wisconsin general test apparatus

A semiautomatic version of the Wisconsin General Test Apparatus is described along with circuitry. Comparison data are provided for the semiautomatic and manual WGTA obtained under comparable procedures and conditions. Response latencies are given for go/no-go object discrimination problems and subsequent retention tests.     

Preprocessing on the basis of frequency of occurrence

The release from PI methodology was used to test Oldfield's (1966) suggestion that human memory is organized in part on the basis of frequency of occurrence. An observed release from PI identified frequency of occurrence as an encoding category and provided support for the underlying assumptions of Oldfield's model.     

Discriminative and associative aspects of retroactive inhibition

Original learning of paired drawings of meaningful objects or of modified Chinese characters was followed by interpolated learning in which details of drawings were changed in one of two degrees with or without rearrangement of the original pairings. Subjects were tested for accuracy of identification of the original drawings and for associative matching of the original pairs. Identification errors were attributed jointly to confusion between original and interpolated drawings, and to unlearning of those features of original drawings which were in conflict with comparable features of interpolated drawings. Rearrangement of pairs during interpolated learning produced not only associative interference on the matching test, but also additional discriminatory interference on the identification test. Effects of associative and discriminative interference upon individual drawings were uncorrelated for meaningful material and only slightly correlated for meaningless material.     

Rate-dependent effects of drugs: modification by discriminative stimuli of the effects of amobarbital on schedule-controlled behavior

Food-deprived pigeons responded under a 10-min fixed-interval schedule of food presentation. During even-numbered minutes of the schedule, the discriminative stimuli were the same as those present when food was delivered. During odd-numbered minutes there was either a change in keylight color or a change in overhead illumination, either for the entire duration of the odd-numbered minutes, or for 3-sec after each response. Responding during even-numbered minutes showed the usual pattern of positive acceleration; responding during odd-numbered minutes was similarly graded, but rates were much lower. The response-rate-increasing effects of amobarbital were inversely related to control rates of responding for both even- and odd-numbered minutes. However, when the stimulus change during odd-numbered minutes was either keylight color or a change from a darkened to a brightly illuminated chamber, increases in responding were considerably less than predicted on the basis of the effects on responding during even-numbered minutes. When the stimulus change was from a darkened to a dimly illuminated chamber, control rates of responding changed little, but increases in responding during odd-numbered minutes after amobarbital were considerably greater, and of the approximate order expected on the basis of control rate.     

Behavioral discrimination of click intensity in cat

Avoidance conditioning procedures were used to train cats to discriminate intensity differences between successive clicks. The discriminative behavior was applied in a modified method of adjustment to determine a difference limen (DL) for click intensity. The obtained DLs were consistent within and between subjects, and averaged 4.4 db. This value is greater than previously reported intensity DLs for pure tones in cats.