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Biomedical subjects

E W Herbert

Publications and source records attributed to E W Herbert.

8 recordsLinked to original sources
PubMed1982

Utilization and metabolism of dietary sterols in the honey bee and the yellow fever mosquito.

The honey bee, Apis mellifera, does not convert C28 and C29 phytosterols to cholesterol as found in most previous studies of phytophagous or omnivorous insects, but instead the workers and queens selectively transfer 24-methylenecholesterol, sitosterol and isofucosterol from their endogenous sterol pools to the brood larvae regardless of the sterol in the worker diet. Administering radiolabeled sterols by feeding and injection has made it possible to trace this selective transfer through a second generation of the honey bee. In further comparative sterol metabolism studies, the yellow fever mosquito, Aedes aegypti, was shown to be capable of dealkylating and converting a radiolabeled C29 dietary sterol ([14C]sitosterol) to cholesterol. Metabolic studies with several radiolabeled dietary sterols and an inhibitor of steroid metabolism in the yellow fever mosquito further verified this capability.

Aedes↗
PubMed1972

Training parents as behavior modifiers: self-recording of contingent attention.

Two mothers of deviant young children were instructed to count their episodes of attention to appropriate child behavior in their homes, using wrist counters. Attention and appropriate child behavior were defined before counting began. Independent observations of parent-child interactions showed that, for each mother-child pair, the percentage of maternal attention given following appropriate child behavior increased, as did the child's appropriate behavior. Removal of the counters did not produce a reversal of the behaviors; instead the increased level stabilized. One mother was then instructed to count her attention to inappropriate child behavior and to decrease it. This instruction had little effect on her attention, and her child's behavior did not change. When both parents were again instructed to count their episodes of attention to appropriate behavior, further improvements in both mothers, and in their children resulted. These results were obtained despite inaccurate parent self-recording. Follow-up observations made over the next five months showed these behavioral gains to be durable. A third parent and his child were unaffected by this training procedure. Thus, there are instances in which self-recording may function as an effective and economical parent-training technique for effecting improvements in child behavior.

Journal Article↗
PubMed1970

Two-key concurrent responding: response-reinforcement dependencies and blackouts.

Two-key concurrent responding was maintained for three pigeons by a single variable-interval 1-minute schedule of reinforcement in conjunction with a random number generator that assigned feeder operations between keys with equal probability. The duration of blackouts was varied between keys when each response initiated a blackout, and grain arranged by the variable-interval schedule was automatically presented after a blackout (Exp. I). In Exp. II every key peck, except for those that produced grain, initiated a blackout, and grain was dependent upon a response following a blackout. For each pigeon in Exp. I and for one pigeon in Exp. II, the relative frequency of responding on a key approximated, i.e., matched, the relative reciprocal of the duration of the blackout interval on that key. In a third experiment, blackouts scheduled on a variable-interval were of equal duration on the two keys. For one key, grain automatically followed each blackout; for the other key, grain was dependent upon a response and never followed a blackout. The relative frequency of responding on the former key, i.e., the delay key, better approximated the negative exponential function obtained by Chung (1965) than the matching function predicted by Chung and Herrnstein (1967).

Journal Article↗
PubMed1969

Conditional discrimination learning in the pigeon.

Four pigeons received conditional discrimination training in which reinforcement contingencies were related to specific combinations of color and form, but were unrelated to either color or form considered separately. During discrete-trial training, each response in the presence of two of four color-form displays produced reinforcement and terminated the trial; responding to the other two displays was never reinforced, and each such response prolonged the particular trial on which it occurred. Subsequently, the subjects received multiple-schedule training in which responding to either of the displays previously associated with reinforcement was now reinforced on a variable-interval schedule, and extinction was the schedule again correlated with the other two displays. After differential responding to the stimuli was clearly evident, intensity of the combination displays was changed in subsequent training sessions. Complex stimulus control was generally maintained across variation in intensity, although there were temporary disruptions in performance associated with onset of some of the intensity changes. Finally, a component-stimulus test revealed considerably more responding to the forms than to the colors.

Journal Article↗