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Biomedical subjects

R H Dale

Publications and source records attributed to R H Dale.

7 recordsLinked to original sources
PubMed1986

Spatial and temporal response patterns on the eight-arm radial maze.

Six maze-experienced hooded rats were timed during five trials on which they collected water from all arms of an eight-arm radial maze, then made five more choices. All subjects frequently exhibited a "task-completion pause:" The subjects rarely spent more than 1 sec in the center of the maze between choices until they had entered all eight arms, then stopped in the center of the maze. In contrast, the time spent in each arm gradually increased until all of the water had been obtained, then decreased slightly. Four subjects began every trial by choosing eight consecutive adjacent arms. The task-completion pause indicates that these subjects recognized when all of the arms had been entered, without having to repeat one. Therefore, even extreme degrees of response stereotypy do not imply a fundamental dependence on response strategies.

Animals↗
PubMed1986

Interactions between response stereotypy and memory strategies on the eight-arm radial maze.

Three groups of water-deprived rats collected water from the ends of the 8-arm radial maze. Sighted subjects, and subjects blinded either with or without pre-enucleation experience on the radial maze, all retrieved the water efficiently. Most of the subjects exhibited the same response stereotypy, regularly choosing 8 adjacent arms of the maze, then stopping in the center of the maze. The strategies underlying this performance were analysed by interrupting trials and rotating the maze 180 degrees after the subject had made 3 choices. Sighted subjects depended on extramaze stimuli, naive-blind subjects depended on intramaze stimuli and experienced-blind subjects ignored their initial 3 choices after the trial was interrupted. Choice accuracy was equally good whether the subject was returned to the position from which it had been removed, or returned to the opposite side of the central platform. All 3 groups of subjects maintained their stereotyped adjacent-arm responding only as long as such responding was consistent with high choice accuracy. Response stereotypy was prevalent on the radial maze, but response strategies were secondary to memory strategies.

Animals↗
PubMed1983

Dynamic effects of food magnitude on interim-terminal interaction.

We tested the assumption of a facilitatory relation between periodic food presentation and schedule-induced drinking by examination of (a) elicited drinking, (b) drinking in anticipation of food delivery, and (c) possible indirect effects of food delivery on drinking. We exposed rats to a fixed-time 60-second schedule in which interfood intervals ended in either one or four food pellets with equal probability. In Phases 1 and 3, a stimulus signaled the magnitude of upcoming food presentation. In Phase 2, the stimulus was eliminated. Changes in drinking and "head-in-feeder" distributions within interfood intervals demonstrated that head-in-feeder was controlled directly by food presentation, but drinking was not. Head-in-feeder increased and drinking was reduced when large meals began or ended an interval. In Phases 4 to 6, meal size was manipulated across sessions yielding a positive relation between meal size and schedule-induced drinking. We conclude: (1) Schedule-induced drinking is determined by distributions of food-related behavior and results from indirect effects of food delivery; and (2) the amount of schedule-induced drinking and the form of the drinking distributions in this experiment can be accurately explained by two assumptions: (a) Food presentation facilitates food-related behavior through elicitation and anticipation; and (b) food-related behavior and drinking are reciprocally, linearly related.

Journal Article↗
PubMed1981

Radial-maze performance in the rat following lesions of posterior neocortex.

The present experiment was designed t investigate the role of posterior neocortex (areas 17, 18 and 18a) in the maintenance of performance on the radial maze. Following training to criterion on the 8-arm radial maze, rats received either sham operations, bilateral eye enucleations, lesions of posterior neocortex, or combined enucleations and lesions of posterior neocortex. While the enucleated animals with intact brains showed a slight, but significant performance decrement relative to the sham-operated group, the other two groups, with lesions of areas 17, 18 and 18a, each showed a massive deficit. This large deficit was observed even in the group in which both the eyes and neocortex had been removed. These results suggest that the visual projection areas of cortex not only play an important role in the maintenance of accurate radial-maze performance in sighted animals, but that the integrity of these areas is necessary for the maintenance fo criterion performance in blind animals.

Animals↗
PubMed1979

Concurrent drinking by pigeons on fixed-interval reinforcement schedules.

Three experienced pigeons were exposed to at least ten consecutive 100-min sessions on each of three food-reinforced fixed-interval (FI) schedules: FI 50-sec, FI 100-sec and FI 200-sec. Water was freely available. Drinking was largely confined to the first third of each fixed interval, and the mean sessional water intake was directly related to the food-reinforcement rate for each animal. The animals drank very quickly, i.e., 3--4 ml/sec, but the drinking bouts were brief, i.e., 0.8--1.4 sec, and infrequent, i.e., 2--5/hr. The parameters describing concurrent drinking in the pigeon are strikingly different from those describing rats' drinking under similar reinforcement schedules, which may contribute to the difficulty in demonstrating schedule-induced polydipsia in the pigeon.

Animals↗