Biomedical subjects

Lucio Rehbein

Publications and source records attributed to Lucio Rehbein.

3 recordsLinked to original sources

PubMed2005

Developmental study of the hippocampal formation in rhesus monkeys (Macaca mulatta): I. Early ablations spare discrimination learning but not recognition memory.

In clinical cases of amnesia that followed bilateral excisions of medial temporal lobe structures, with some perceptual learning abilities intact, damage to the hippocampus was presumed to be the critical factor. The authors' search for an animal model of amnesia, based on ablations aimed at the hippocampal formation in infant rhesus monkeys, provides support for this view. Ablations of the hippocampal formation in 2-month-old infants tested shortly after recovery from surgery resulted in a deficit on a recognition memory task but left intact the ability to learn the concurrent object discrimination task, even though the latter task was administered with the use of a massed practice procedure. Thus, early damage, unlike that at 2 years of age or later, allowed the authors to dissociate associative learning with repeated trials, independent of hippocampal functions and recognition memory that depends on the integrity of the hippocampus.

Age Factors↗

PubMed2005

Developmental study of the hippocampal formation in rhesus monkeys (Macaca mulatta): II. Early ablations do not spare the capacity to retrieve conditional object-object associations.

A companion article (see record 2005-06959-001) revealed that hippocampectomy in infancy spares concurrent discrimination learning but not recognition memory. The present report describes the results obtained with a more complex task, conditional object- object association, in which rhesus monkeys (Macaca mulatta) had to first learn to discriminate between pairs of objects rather than single ones and to subsequently remember which particular object had been a member of a rewarded stimulus pair (contextual retrieval). Hippocampectomized infants obtained normal scores in learning individual pair discriminations, but they were severely impaired in contextual retrieval. The results are interpreted in terms of a dual-system theory proposed by R. Hirsh (1974). The results point out not only the importance of age at testing but also the nature of the task. The authors were also able to glimpse possible instances of cooperation or competition between the 2 systems.

Age Factors↗

PubMed2002

Students' learning through hypermedia.

This study assessed the effectiveness of hypermedia software in the learning and retention, association, and structuring of biological knowledge by using fifth grade students (ages 9 to 11 years) from three urban schools in Southern Chile. Four groups of 24 subjects each were exposed to either hypermedia software presentation on basic functions of the human body (Group 1), the same information in linear, electronic book mode (Group 2), the same information on a printed brochure (Group 3), or no experimental treatment but exposure (as were students in the other three groups) to regular lectures and materials (control group or Group 4). Six students from each school were randomly assigned to the treatment and control groups; thus 24 students from each school (N=72) participated. Students in all groups increased their retention of information. They also improved their performance on remote concept associations and on construction of conceptual maps. However, the groups who used the software presentation obtained significantly better scores on remote association of concepts. There were correlations for the users' hypermedia navigational patterns with the richness of the students' conceptual maps, and the students' remote association. In general, results support the use of similar software in education wherein the goals are remote associations and rich conceptual maps, and, more specifically, they indicate that the students' navigational pattern through information could serve them better to structure and relate conceptual information.

Biology↗