Biomedical subjects

R R Michels

Publications and source records attributed to R R Michels.

2 recordsLinked to original sources

PubMed1989

Effects of [D-Ala2] Met-enkephalinamide, a Met-enkephalin analog, on delayed response by squirrel monkeys.

Squirrel monkeys were tested on an indirect spatial delayed response task after subcutaneous injections of either physiological saline, 100, or 500 microgram/kg [D-Ala2] methionine enkephalinamide (DAME). During Experiment 1 monkeys completed two-choice delayed response problems with 0-, 6-, 12- and 18- sec delays; DAME significantly enhanced performance at 18-sec delays but not for the shorter delay. During Experiment 2, monkeys performed a nine-choice spatial delayed response task with 0-, 4- and 8-sec delays. In Experiment 2, low but not high doses of DAME impaired performance. Memory functions represented by a bias-free performance measure paralleled percentage correct in both experiments. Therefore, DAME effect, in enhancing and in impairing performance, were not attributable to changes in the relative number of systematic spatial errors (positional win-shift; lose-stay, position perseveration, and position preference).

Animals↗

PubMed1988

Preference differences for sucrose solutions in young and aged squirrel monkeys.

Licking patterns and molarity preferences, elicited by two sets of sucrose solutions (0.0 to 1.75 M and 1.0 to 3.0 M), were measured in six young and six aged squirrel monkeys. Sucrose preference thresholds were determined for each age group using sucrose concentrations from 0.025 to 0.1 M. Age was unrelated to sucrose preference thresholds. Consummatory activity of all monkeys increased monotonically as sucrose concentrations increased from 0.0 to 1.0 M. Aged, but not young, monkeys continued to increase consumption until sucrose concentrations exceeded 1.5 M. All monkeys increased consumption by increasing number of licks, number of licking bursts and total time spent licking. Unlike young monkeys, aged monkeys displayed high within animal variability of tongue contact times, exponentially decreasing rates of licking at high molarities, constant consumption efficiency decrements, and consistent negative correlations between tongue contact and following tongue off times.

Aging↗