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Biomedical subjects

D A Kramer

Publications and source records attributed to D A Kramer.

4 recordsLinked to original sources

Pattern generator system as a versatile visual stimulator.

We have designed and implemented a Motorola 68000 microprocessor-based pattern generator system (PGS) that uses a color video display terminal (VDT) to provide light stimuli to the intact vertebrate retina. This communication is intended for those who are considering acquisition of a commercial retinal stimulator or those who are custom designing their own pattern generator system. The discussion surveys the features to be included as well as design factors which must be considered in such a device. The memory organization of the PGS allows as stimuli multiple, complex patterns consisting of one or more disks, annuli, bars or gratings to flash or modulate in intensity according to a pre-defined function. In addition, patterns can move smoothly in any direction at selectable, uniform speeds without the re-drawing of video memory. The presence of a 12-bit A/D converter internal to the PGS allows a dynamic change in stimulus position, speed or pattern based upon physiological feedback. A physically realistic image size (0.9 cm2) and resolution (20 mu/pixel) in the retinal plane are achieved with simple intervening optics. The video field rate of 60 Hz is above the flicker fusion frequency for most vertebrate animals and does not induce artifacts in cellular responses. The PGS operating in a PC-based environment meets the requirements of a versatile optical stimulator for investigations in retinal electrophysiology.

Ambystoma

A measure of paradigm beliefs about the social world.

This study examined the reliability and construct validity of, along with age differences in, a measure of paradigm beliefs about the social world, beliefs that have been proposed to develop across the adolescent and adult life span. The scale is a 27-item, forced-choice preference measure of absolute, relativistic, and dialectical paradigm beliefs. In a series of investigations with 445 subjects, ranging in age from 16 to 83 years, it was shown to have good internal consistency and test-retest reliability, and both convergent and discriminant validities. It predicted performance on an in-depth interview about paradigm beliefs and was related to two other measures of paradigm beliefs. It was not related to selected personality variables (i.e., social dogmatism, intolerance of ambiguity and social desirability); nor was it related to a measure of verbal intelligence. The scale also showed predicted developmental trends, supporting its utility for developmental research.

Adolescent

EEG alpha slowing, refractory period, and reaction time in aging.

The present study was undertaken to determine if a model accounting for reaction time (RT) on the basis of the EEG alpha rhythm and refractory period (RP) could predict RT in young and old adult subjects. Ten male university undergraduates and ten community residing males over the age of 65 had resting EEG recorded at right and left occipital sites. Mean alpha frequency was 1.2 Hz slower in old subjects. RT and RP were assessed in a warned RT paradigm. Sixty-four trials of each of a 50, 100, 250, and 500 msec inter-stimulus interval (ISI) were presented in random order. The model was useful in predicting the magnitude of the age difference in RT and the difference in RT between the 50 and 100 msec ISI. However, old subjects were not disproportionately slowed at the 100 msec ISI as the model would predict and all RTs were underestimated. Thus, while a model using EEG alpha period and RP to predict age differences in RT has some weaknesses, it is useful enough to warrant additional examination.

Adult

The overlapping territories of psychiatry and ethology.

There have been numerous attempts since 1965 to stimulate more utilization of ethological methods and concepts in psychiatry. This literature is reviewed and an attempt is made to identify the factors which have inhibited an enhancement of this interaction to date. Most of the previous articles on this subject have appeared in edited collections, rather than in more widely circulated psychiatric or medical journals. Some of the articles focus on ethological theory, others on ethological research findings, and several on clinical analogies between animal and human situations. Regarding the specific way in which to integrate ethological thought into psychiatry, most frequently a phylogenetic approach is emphasized, however a few authors stress methodological considerations. In this paper, it is argued that artifactual differences have been the primary impediment to more interaction between these two rather similar fields. Scientific language difficulties, educational differences, and personal factors are described in this regard. Also, the real differences in approach and methodology, relative interest in normal vs. abnormal behavior, the degree of willingness to accept a phylogenetic approach, and the breadth of behavior being studied by the two fields are described. Examples of current areas of applicability of ethology to psychiatry are given: the attachment systems, early infantile autism, methodology, social psychiatry, and psychiatric education. Of these, the area where the most utilized is that of the occurred and in which the findings of ethology have been the most utilized is that of the attachment systems. Clinically applicable studies based upon the premise that attachment systems exist as understood ethologically are reviewed. These include study of extra physical contact between mothers and infants at birth, the prediction of child abuse and neglect utilizing observations from the immediate postpartum period, the treatment of failure to thrive by teaching attachment behavior, and developmental differences at 1 year correlated with differences in maternal responsiveness at 3 months. The usefulness of a biological approach to behavior is discussed, particularly in terms of utilizing operational criteria and from the point of view of differentiating etiological, phenomenological, and treatment models. A curriculum stressing the writings of Tinbergen, Lorenz, Bowlby, and Hailman is presented for possible use in psychiatric training programs interested in teaching an ethological approach to psychiatry. A briefer curriculum is also suggested from the psychiatric literature for use by ethologists. The epistemology and methodology of ethology possible will be of more use to psychiatry than the content. It is the opinion of the authors that the difficulties which have inhibited significant cooperation between psychiatry and ethology in the past are mostly artifactual, that such cooperation could be useful to both fields, and that a beginning to such interaction will require mutual familiarity with the literature.

Adult