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Biomedical subjects

G Turkewitz

Publications and source records attributed to G Turkewitz.

At least 37 records · Page 2Linked to original sources
PubMed1980

Development of home orientation in hypothyroid and hyperthyroid rat pups.

In order to assess the effects of perinatal hypothyroidism or hyperthyroidism on the development of an integrated behavioral response, we tested hypothyroid, hyperthyroid, and control pups, as well as pups receiving thyroxine replacement therapy, for the development of the home orientation response. Hypothyroidism was induced in the pups by feeding the pregnant or lactating female a diet of .2% propylthiouracil from Day 15 of gestation to Day 22 postpartum. Pups receiving replacement therapy and pups made hyperthyroid were injected daily with thyroxine, starting at birth. The ability of the pups to initiate and maintain locomotion toward the nest was assessed between Days 4 and 22. Hyperthyroid, control, and replacement therapy pups behaved very similarly on the task, showing a peak in the percentage of pups homing between Days 12 and 16. Hypothyroid pups showed a delay in the peak percentage until Day 20, although the percentage of pups was similar to that found in other treatments. An integrated behavioral response can be delayed by hypothyroidism and still emerge apparently intact at a later age.

Animals↗
PubMed1980

Varying deficits in visual discrimination performance associated with different forms of malnutrition in rats.

Visual discrimination at 3 months of age was examined by the Lashley jumping stand test to rats malnourished by one of the following techniques: intergenerational malnutrition over 14 to 18 generations; protein deficiency from birth on; rearing in large litters, and rotation among lactating and non-lactating females. All four treatments caused stunting during the litter period, but only the first two were associated with reduced weights at the time of testing. Deficits in visual discrimination were most severe in males and females with intergenerational malnutrition. Both large-litter rearing and protein deficiency for one generation impaired visual discrimination in males only, whereas rotation between lactating and non-lactating females did not reduce visual discrimination in either gender. It is possible that extranutritional factors associated with each type of malnutrition may serve either to enhance or diminish the impact of malnutrition on the nervous system.

Animals↗
PubMed1980

Intersensory function in newborns: effect of sound on visual preferences.

The results of this study indicate that newborn infants' fixation of a graduated series of visual stimuli comprised of a low (1), intermediate (4 or 16), and a high (64) number of cubes is significantly different in the absence and presence of sound (white-noise bursts). Relative to the no-sound condition, sound resulted in the infants' tendency to look more at the low-intensity visual stimulus and less at the high-intensity visual stimulus. These results provide support for the idea that the newborns' optimal or preferred amount of stimulation is based on the total amount or intensity of stimulus input, regardless of whether this is contributed to by stimulation from one or more than one modality.

Attention↗
PubMed1979

Effect of neonatal stunting on development of rats: large litter rearing.

As nurslings, rat pups reared in large litters showed reduced frequencies of returns to their nest from other parts of the home cage and reached maximum levels of nest returns at older ages than control animals from small litters. These differences were not due to differences in activity level or attraction to the nest but appeared to be perceptual in nature. As adults, animals from large litters showed deficits in learning the 1st 2 problems in a series of visual discriminations in a modified version of the Lashley jumping stand technique in which food reinforcement was not used. The deficits were confined to male animals only and were the result of stronger position habits in the early part of training, rather than an inability to make the discriminations. A comparison of these results with those obtained when other methods of stunting animals are employed revealed that different methods of stunting may result in both common and divergent effects on behavior. One long-term consequence of large litter rearing appears to be increased emotional response to noval situations.

Animals↗
PubMed1979

Behavioral effects of rotation between lactating and nonlactating females.

Rat pups stunted by housing only 8 hr daily with lactating females and 16 hr with nonlactating foster mothers showed a delay in returning to their nest from other parts of the home cage. This delay was not due to changes in activity level or to lack of attraction to the nest, but appeared to be perceptual in nature. Both lactating and nonlactating females caring for stunted litters tended to be more maternal than those caring for control pups. After nutritional rehabilitation, the adult experimental animals showed no deficits in learning a series of visual discrimination problems in a modified version of the Lashley jumping stand procedure with a nonappetitive reinforcement. We compared the results with those obtained when other methods of stunting animals are employed and concluded that different methods of stunting may result in both common and divergent effects on behavior. Although many methods of stunting may produce similar behavioral deficits during the period of food deprivation, after rehabilitation behavioral deficits reported with other techniques of stunting may be due to extranutritional causes rather than to reduced food intake per se.

Animals↗
PubMed1979

Lateral differences and head-turning responses to somesthetic stimulation in premature human infants.

Head-turning responses to somesthetic stimulation of the perioral region were studied at weekly intervals in 25 prematurely born infants. No regular changes associated with age were evident. The premature infants were more likely to turn towards than away from a stimulus; however, they were less so than are full-term infants. The infants were as likely to turn towards the stimulus when it was on the left as when it was on the right; however, they were more likely to turn away from a stimulus on the left than on the right. Comparisons with full-term infants indicated reduced lateral differences in responding. Such a reduction is in sharp contrast with the previous finding of marked postural asymmetry in a comparable sample of prematurely born infants. These data indicate a possible sequence in the development of head-turning responses to somesthetic stimulation and the assumption and maintenance of an asymmetrical head posture which consists of (1) a right-turning postural bias, (2) contralateral responding to somesthetic stimulation, (3) lateral differentiation of contralateral responding, (4) ipsilateral responding, and (5) lateral differentiation of ipsilateral responding.

Female↗
PubMed1979

Changing role of stimulus intensity as a determinant of infants' attention.

When pairs of stimuli which varied in size or brightness and in pattern were presented to 6-, 9- and 24-wk.-olds, the visual attention of the younger infants appeared to be more influenced by size or brightness than by pattern, while the opposite was the case for the oldest infants. The results of another study suggested that the effects of size and brightness were additive for 9-wk.-olds. Finally, a third study using a subject-control procedure with successive stimulus presentation yielded results which were essentially the same as those of the first study. The results were interpreted as supporting the hypothesis that amount of stimulation is a major determinant of attention in the first 2 mo. and that its effectiveness decreases with age.

Attention↗
PubMed1978

Visually elicited finger movements in infants.

The relationship between visual stimulus intensity and finger movements was examined in infants from 10 to 15 weeks of age and from 20 to 25 weeks of age who were shown a cone that varied in size, brightness, and distance from them. 2 hypotheses derived from Schneirla's approach-withdrawal theory were examined; (1) that responses of the younger infants would be directly related to stimulus intensity, with finger extension (approach) movements elicited by weak stimuli and flexion (withdrawal) movements elicited by more intense stimuli; and (2) that stimulus dimensions such as distance, size, and brightness would make additive contributions to stimulus intensity, so that combinations of weak intensity would elicit finger extension and combinations of strong intensity would elicit flexion. Analyses of variance indicated no significant main effects of distance, size, or brightness, but significant age, intensity, and age x intensity effects. Older infants tended to extend their fingers more than younger infants. However, as intensity increased, the younger infants' responses showed decreases in extension and increases in flexion, while the older infants' responses indicated no clear relationship between intensity and response direction. That younger infants were responsive to the quantitative rather than the qualitative aspects of stimulation has important implications for understanding how various stimulus dimensions affect infant responses.

Age Factors↗
PubMed1977

Development of postural asymmetry in premature human infants.

The head position of 95 infants, born between 30 and 37 weeks gestational age, was observed every 15 min for 2 hr weekly from birth until 39 weeks conceptional age. At 35 weeks and increasingly thereafter, significantly more time was spent with the head to the right than to the left. By 39 weeks the infants were similar to term infants: almost 90% spent 80% or more time with their heads to the right. The increase appeared independent of intra- or extrauterine experience; neither age at birth nor time since birth was consistently related to head position. Unlike term infants, prematures were equally likely to turn left as right and have their heads left as right 15 min after release from a midline position. These findings suggest complex determinants of asymmetry including factors intrinsic to the fetus and those contributed by the uterine environment.

Female↗
PubMed1977

Motor competence in rats of different stocks reared in large and small litters.

The effects of sex and stock on a task of motor competence (balancing on a rod) were studied in Long-Evans, Sprague-Dawley and Wistar rats reared in large and small litters. The data indicated significant sex and stock effects but no effects of rearing condition. Although no nutritional effect was found on this task, the data suggest that stock differences should receive greater attention particularly with regard to the possibilities that such differences provide for the identification and analysis of a broad spectrum of effects.

Animals↗
PubMed1977

Use of partial mammectomy to produce malnutrition in the rat.

Partial mammectomy in the Sprague-Dawley rat was studied as a method for producing malnutrition without accompanying differences in litter size. Throughout the litter period, experimental litters weighed less than controls. No difference in the rate of development of various anatomical landmarks was noted with this degree of malnutrition. Maternal behavior in the nursing dam was measured with respect to nursing, nesting, and retrieval behavior. Mammectomized subjects built and maintained better nests and spent more time in a nursing posture, but were less likely to retrieve their litter than were control animals. At weaning the intact mammae of the experimental animals were larger than those of control animals.

Animals↗
PubMed1977

Environmental characteristics of a neonatal intensive-care unit.

An increasing number of intervention programs are designed to ameliorate the "sensory deprivation" of hospitalized premature infants. However, observation of the premature infant's hospital environment every 15 min for 5 24-hour periods indicated that acoustic stimuli were clearly audible in over 95% of the observations, infants were handled during more than 10% of the times they were observed, and illumination levels were always sufficiently high to permit easy visibility. Analysis of the nature of this stimulation suggests that premature infants may suffer from an inappropriate pattern rather than an inadequate amount of stimulation.

Acoustic Stimulation↗
PubMed1975

Changes in lateral differentiation of head posture in the human neonate.

Developmental changes in the relationship between lateral differences in responsiveness and the assumption of asymmetrical head postures were examined. The head turning of 70 infants ranging in age from 0-72 hr was observed following a procedure (maintenance of the head in a midline position) known to reduce or eliminate lateral differences in the infant's response to stimulation. Even following this procedure infants older than 12 hr made significantly more right than left head turns whereas younger infants exhibited no such difference. When lateral differences in sensitivity were not interfered with in 0 to 12 hr old infants (n=20) they, kile the older infants, made significantly more right than left turns. These results are discussed in terms of possible developmental consequences of a reciprocity between asymmetric head position and lateral differences in sensitivity.

Age Factors↗
PubMed1975

Variability of the effects of rearing in a large litter on the development of the rat.

The variability in the effects of rearing rats in large litters was examined. Subjects reared in litters of 16 were stunted and delayed in the appearance of eye-opening and fur-eruption as compared with pups reared in litters of 8. However, the effects of the large-litter treatment were not uniform; pups in this group exhibited markedly higher variability with regard to all measures than did pups from small litters. In fact, some pups from the large litters were heavier and some exhibited developmental landmarks earlier than did most pups reared in small litters.

Age Factors↗
PubMed1975

Relationship between effective intensity of auditory stimulation and directional eye turns in the human newborn.

To examine Schneirla's biphasic hypothesis that effectively weak stimulation results in approach-type responses and effectively strong stimulation results in withdrawal-type responses, 90 dB white noise stimuli were presented to twenty-five, 2-day-old female infants. Based on prior investigation this stimulus was expected to be effectively strong when presented at the right ear and effectively weak when presented at the left ear. Results obtained from electro-oculargraphic recording of the infants' eye movements supported this hypothesis in that significant towards-turning occurred when the stimulus was presented at the left ear and significant away-turning occurred when the stimulus was presented at the right ear.

Acoustic Stimulation↗