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Biomedical subjects

R H Bauer

Publications and source records attributed to R H Bauer.

At least 19 recordsLinked to original sources
PubMed1991

Allocation of study time and recall by learning disabled and nondisabled children of different ages.

Study time and recall by learning-disabled and nondisabled children of five different ages were examined in a task requiring recall of digits that were presented at the child's own rate. Recall increased with age and was significantly higher by nondisabled than disabled children, particularly at older ages. As additional digits of each sequence were presented, study time by 8-year-old disabled and nondisabled groups were relatively constant, increased in older disabled and nondisabled children, but increased more in older nondisabled children than older learning disabled children. Instructions in hierarchical grouping of digits increased recall by all groups to a similar degree, but the increase by younger children and learning disabled children was associated with longer study times. The results suggest that allocation of study time and recall are developmentally delayed in learning disabled children.

Achievement↗
PubMed1990

The effect of increased incentive on free recall by learning-disabled and nondisabled children.

Immediate free recall by learning-disabled and nondisabled children was compared under two incentive conditions. Recall of the first few words of each list by disabled children and younger nondisabled children was lower than that by older nondisabled children, and receiving a monetary reward increased early list item recall by older disabled and nondisabled learners. These findings suggest that elaborative encoding processes, such as rehearsal, are impaired in younger disabled and nondisabled children and that receiving a reward increased elaborative encoding by older children. Similar recall of the last few list items by all groups suggests that attention and immediate memory are comparable in disabled and nondisabled children of different ages. Receiving a reward increased recall of the last few list items by younger disabled and nondisabled children, suggesting that a reward increased attention, immediate memory, or both, in these groups. Because receiving a reward increased recall equally in all groups, lower motivation did not appear to be responsible for the lower recall by younger nondisabled children and learning-disabled children.

Attention↗
PubMed1985

Functional interactions between inferotemporal and prefrontal cortex in a cognitive task.

Monkeys were trained to perform a visual short-term memory task (delayed matching to sample). In some of the animals, cooling probes were implanted over dorsolateral prefrontal cortex, covering sulcus principalis and adjacent areas; microelectrode pedestals were implanted over inferotemporal cortex. Other animals were fitted with converse implants: cooling probes over a portion of the inferotemporal cortical convexity and microelectrode pedestals over prefrontal cortex. In the awake and behaving monkeys, bilateral cooling of either the prefrontal or the inferotemporal region (to 20 degrees C) induced, in the other region, reversible changes of spontaneous and task-related cell discharge. In the two cortices remote cooling induced augmentations and diminutions of cell reaction to the color samples which the animal had to retain for correct performance of the task. The same was true for cell discharge during the delay, the retention period which followed each sample. However, a net effect of remote cooling was, in both cortices, a diminution of color-dependent differences in the reactions and delay-discharge of some cells. Concomitantly, errors of task-performance increased. Cells that as a result of remote cortical cooling showed changes of reaction to the color samples were found more commonly in supragranular than infragranular layers. The results are interpreted as evidence of mutual influences between inferotemporal and prefrontal areas, probably mediated by corticocortical connections. The single-cell data, together with the behavioral data, suggest that those influences are functionally important for visual discrimination and short-term memory.

Action Potentials↗
PubMed1984

Information processing in reading-disabled and nondisabled children.

Reading disabled and nondisabled children (13-14 years of age) were presented lists of 10 words each at different rates (one word per 1, 2, and 4 sec), and immediately after the last word of each list they recalled the words in any order. Recall of the first few words presented from each list (the primacy effect) was lower in reading-disabled than nondisabled children, and slower presentation rates increased the primacy effect in both groups. These findings suggest that reading-disabled children are not completely failing to use elaborative encoding but are using less effective elaborative encoding than nondisabled readers. With all presentation rates, recall of the last few words (the recency effect) was comparable in both groups, suggesting that older reading-disabled children encode and recognize the stimuli and that elaborative encoding is deficient in reading-disabled in spite of adequate stimulus encoding and recognition.

Adolescent↗
PubMed1984

Differential effects of d-amphetamine and scopolamine on the ontogeny of rearing.

Although rearing is ontogenetically an important behavior, very little is known about the neural bases of rearing. The role development of catecholaminergic and cholinergic neurons play in the ontogeny of rearing was investigated by examining rearing in infant, adolescent, and adult rats following various doses of d-amphetamine (an indirectly acting catecholaminergic agonist) and scopolamine (a cholinergic muscarinic receptor antagonist). d-Amphetamine increased rearing in infants but not in adolescents and adults. These findings suggest that activation of catecholaminergic neurons increases rearing in infants but not in adolescents or adults. Scopolamine increased rearing in adolescents and adults but not in infants, indicating that blocking transmission of cholinergic neurons increases rearing in only older rats.

Aging↗
PubMed1982

Ontogenetic differences in response to d-amphetamine: two-way avoidance, intertrial responses, and locomotor activity.

In Experiment 1, 15-, 17-, 21-, 36-, and 90-day-old rats were injected with either physiological saline, 0.5-, 1.0-, 4.0-, 8.0-, or 16.0-mg/kg of d-amphetamine sulfate and 20-min later they were allowed to explore a two-way avoidance apparatus for 8 min. Immediately following adaptation, they were given a single session of 100 two-way avoidance trials. In general, in all ages, there was a dose related increase in avoidance on the first block of trials. However, across trials avoidance of the two youngest ages decreased, avoidance responding by 21-day-old animals remained relatively constant, and avoidance of the oldest ages increased. In the three youngest ages, avoidance and intertrial responses had a similar pattern, but in older ages there was little relationship between avoidance and intertrial responses. Shuttle crossings during adaptation were increased more by higher doses in younger rats than adults. In Experiment 2, para-hydroxyamphetamine (1.0, 4.0, 16.0 mg/kg) did not alter two-way avoidance, intertrial responses, or crossings during adaptation in 15-, 17-, 21-, 36-, or 90-day-old rats. The age-dependent behavioral effects of d-amphetamine may be due to maturation of central nervous system catecholaminergic neurons.

Aging↗
PubMed1982

Age-dependent effects of scopolamine on avoidance, locomotor activity, and rearing.

In Experiment 1, 15-, 17-, 21-, 36- and 90-day-old rats were injected with either physiological saline or 0.5, 1.0, 4.0, 8.0, 16.0 or 32.0 mg/kg of scopolamine (an anticholinergic). Immediately after the injection, shuttle crossings during adaptation were recorded for 8 min, and then the rats were given a single session of 100 two-way avoidance trials. In all ages, scopolamine increased two-way avoidance and intertrial responses throughout training and avoidance and intertrial responses were positively correlated, suggesting that increased avoidance was due, in part, to increased locomotor activity. In addition, scopolamine increased locomotor activity at an earlier age in a stressful situation, i.e. during the intertrial interval, than in a less stressful environment, i.e. during adaptation. In Experiment 2, photocell crossings and rearing were examined in 15-, 17-, 21-, 36-, 90- and 275-day-old rats injected with saline or 0.5, 1.0, 4.0, 8.0 or 16.0 mg/kg of scopolamine hydrobromide. Scopolamine increased photocell crossings in rats 21 days of age and older but did not increase rearing until 36 days of age. Scopolamine also had different behavioral effects in the three oldest ages. Thus, cholinergic involvement in these behaviors changes from at least 15 to 275 days of age. Methylscopolamine, which does not cross the blood-brain barrier, did not alter the behaviors examined in Experiments 1 and 2, suggesting that development of cholinergic neurons in the CNS is responsible for the age-dependent behavioral effects of scopolamine.

Acetylcholine↗
PubMed1981

Single cell activity in ventral prefrontal cortex of behaving monkeys.

Single unit activity was recorded extracellularly from ventral prefrontal cortex (VPC) of monkeys during performance of two short-term memory tasks: spatial delayed response and delayed matching to sample. The tasks required perception, retention and recognition of visual cues differing in either color or spatial location. Two separate areas of VPC were explored: a lateral area in the lower prefrontal convexity and a medial area around the medial orbital sulcus. Two categories of unit activity were distinguished on the basis of frequency changes to the cue. One was characterized by non-specific discharge independent upon which cue was presented, the other by discriminative discharge related not only to visual qualities of the cue but to the animal's subsequent use of it. Nearly one-half of all units showed altered firing during the retention (delay) period as compared with intertrial control firing. Eighteen per cent displayed delay activity related to the quality of the preceding cue. The lateral and medial segments of VPC were not distinguished by differences of unit activity in cue or delay periods. Post-trial activity was related to presence or absence of reward. Type I cells showed firing changes following choice reinforcement as well as gratuitous reward; some showed changes in opposite direction following unreinforced choices. They may encode the availability of reward. Type II cells showed changes of activity after unreinforced trials and, in some cases, opposite changes after unexpected reward; they were not affected by the reward of normal correct-choice trials. These cells appear to react to deviations from expectancy of reward. Type III cells exhibited comparable firing changes following reinforced and unreinforced choices. They may encode termination of a trial sequence. Type I was more common in lateral than medial VPC, whereas the opposite was true for type II; type III did not clearly predominant in either area. Ablation studies have shown that the two areas of VPC differ in behavioral functions. This study of their cellular properties revealed topographic differences only during the post-trial period. It is therefore possible that the combination of cue and delay activity (related to exteroceptive input) with post-trial activity (related to interoceptive input) constitutes the neuronal basis for the two areas' differences in behavioral function.

Animals↗
PubMed1978

Ontogeny of two-way avoidance in male and female rats.

In Experiment I, 17-, 21-, 36-, 51-, 90-, and 200-day-old male and female rats were given a single session of 100 two-way avoidance (TWA) trials. In the 2nd experiment, males and females of these ages and 15 and 28 days of age that were obtained from a different source, weaned at a later age, and housed differently received TWA training. Results of both studies showed that avoidance of 15-, 17-, and 21-day-old rats is low, but avoidance increases from 21 to 51 days of age. Avoidance of 95- and 200-day-old animals was generally lower than 51-day-old rats. No significant gender differences appeared until 90 days of age; at this age avoidance of males was lower than females. In Experiment III, CS intensity was varied and the US intensity was lower than that used in Experiment I and II. Avoidance of 21- and 90-day-old rats was higher with a more intense CS, but 21-day-olds were still lower than adults. Avoidance of 17-day-old rats was not affected by CS intensity.

Aging↗
PubMed1978

Effects of d-amphetamine and prefrontal cortical cooling on delayed matching-to-sample behavior.

The interaction was examined between d-amphetamine (s-A) and dysfunction induced by localized cooling of the dorsolateral prefrontal cortex. Saline or d-A(0.1,0.2 or 0.4 mg/kg) was administered to monkeys in two conditions; normal cortical temperature (no cooling -NC) and frontal cooling (FC). Errors, reaction time (RT), eye movements, and motor activity were recorded during performance of a delayed matching-to-sample task with intratrial delays of 1-32 sec. Although d-A and FC had little effect on percentage of correct responses at the shortest delay, each of the two treatments significantly decreased correct responses, at longer delays; drug and FC combined produced a significantly greater decrease than either treatment alone. Motor activity and eye movements were increased by either d-A or FC; the two treatments combined had an even greater effect. In the NC condition, two-choice RT was decreased by the drug; it was increased by drug-FC combinations. These findings indicate that d-A and FC potentiate each other in their behavioral effects.

Animals↗