Biomedical subjects

J A Dusek

Publications and source records attributed to J A Dusek.

4 recordsLinked to original sources

PubMed2001

Relational learning with and without awareness: transitive inference using nonverbal stimuli in humans.

Learning complex relationships among items and representing them flexibly have been shown to be highly similar in function and structure to conscious forms of learning. However, it is unclear whether conscious learning is essential for the exhibition of flexibility in learning. Successful performance on the transitive inference task requires representational flexibility. Participants learned four overlapping premise pairs (A > B, B > C, C > D, D > E) that could be encoded separately or as a sequential hierarchy (A > B > C > D > E). Some participants (informed) were told prior to training that the task required an inference made from premise pairs. Other participants (uninformed) were told simply that they were to learn a series of pairs by trial and error. Testing consisted of unreinforced trials that included the non-adjacent pair, B versus D, to assess capacity for transitive inference. Not surprisingly, those in the informed condition outperformed those in the uninformed condition. After completion of training and testing, uninformed participants were given a postexperimental questionnaire to assess awareness of the task structure. In contrast with expectations, successful performance on the transitive inference task for uninformed participants does not depend on or correlate with postexperimental awareness. The present results suggest that relational learning tasks do not necessarily require conscious processes.

Adult↗

PubMed1999

Self-reported health, and illness and the use of conventional and unconventional medicine and mind/body healing by Christian Scientists and others.

A cross-sectional national telephone survey was used to determine whether Christian Scientists (N = 230), a religious group that uses mind/body (including spiritual) healing, self-report more or less illness than non-Christian Scientists (N = 589). The primary outcome measure was the proportion of Christian Scientists and non-Christian Scientists that, during the previous 12 months: a) experienced any of 13 common medical conditions or symptoms; and b) used conventional medicine, unconventional medicine, and mind/body (including spiritual) healing. Fewer Christian Scientists experienced an illness or symptom than non-Christian Scientists (73% vs. 80%, respectively, p = .05). A multivariate analysis showed that Christian Scientists were less likely to have experienced illness than non-Christian Scientists (odds ratio [OR] .66, 95% confidence interval [CI] .44 to .99, p = .04). Similar proportions of Christian Scientists and non-Christian Scientists used some type of conventional medicine (74% vs. 78%, respectively), although Christian Scientists were less likely to take prescription medications than non-Christian Scientists (p = .034). Although use of unconventional medicine was similar in both groups (52% vs. 45%), more Christian Scientists than non-Christian Scientists used at least one type of mind/body medicine (67% vs. 42% p < .00001), notably special religious services and spiritual healing. Additional studies are needed to determine whether there are health benefits associated with the use of conventional and unconventional medicine in combination with mind/body (including spiritual) healing.

Adolescent↗

PubMed1998

The hippocampus and transverse patterning guided by olfactory cues.

Normal rats and rats with hippocampal system damage were trained on a novel, olfactory version of the transverse-patterning task that involved the concurrent learning and continued performance of 3 partially ambiguous discrimination problems (A+B-, B+C-, C+A-). Animals with lesions of the fornix or perirhinal-entorhinal cortex acquired at least as rapidly as normal rats these problems presented in sequential blocks of trials involving the same stimulus pair. All groups also performed well on an initial test session when the order of stimulus pair presentations was randomized. Normal rats continued to discriminate appropriately in additional testing sessions with trials presented in random order. By contrast, both groups with hippocampal system damage performed poorly in continued random-order testing. These results extend the generality of the deficit in transverse patterning to the olfactory modality and demonstrate that the deficit is equivalent in magnitude after fornix or perirhinal-entorhinal damage. Findings also suggest that the transverse-patterning problem can be acquired transiently without critical hippocampal involvement, although continued performance relies on hippocampal function.

Analysis of Variance↗

PubMed1997

The hippocampus and memory for orderly stimulus relations.

Human declarative memory involves a systematic organization of information that supports generalizations and inferences from acquired knowledge. This kind of memory depends on the hippocampal region in humans, but the extent to which animals also have declarative memory, and whether inferential expression of memory depends on the hippocampus in animals, remains a major challenge in cognitive neuroscience. To examine these issues, we used a test of transitive inference pioneered by Piaget to assess capacities for systematic organization of knowledge and logical inference in children. In our adaptation of the test, rats were trained on a set of four overlapping odor discrimination problems that could be encoded either separately or as a single representation of orderly relations among the odor stimuli. Normal rats learned the problems and demonstrated the relational memory organization through appropriate transitive inferences about items not presented together during training. By contrast, after disconnection of the hippocampus from either its cortical or subcortical pathway, rats succeeded in acquiring the separate discrimination problems but did not demonstrate transitive inference, indicating that they had failed to develop or could not inferentially express the orderly organization of the stimulus elements. These findings strongly support the view that the hippocampus mediates a general declarative memory capacity in animals, as it does in humans.

Animals↗