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Biomedical subjects

L C Mayes

Publications and source records attributed to L C Mayes.

66 records · Page 4Linked to original sources
PubMed1990

Emerging social regulatory capacities as seen in the still-face situation.

Early mother-infant interactions support infants' abilities to deal with stressful situations such as the withdrawal of maternal attention. The "still-face" paradigm provides a framework for studying the range of social regulatory capacities available to infants during stressful times. This study examined the responses of 62 3-4-month-old infants during the still-face situation. Infants' responses were coded in real time along 3 dimensions: gaze, affect, and state. 3 findings are presented: (1) Generally, infants responded to the still-face situation with predominantly neutral affect and looking away from their mothers. (2) Infants who looked longer at their mothers early in the still-face showed longer early positive affect and protested her absence less. (3) Girls more often showed an intensely negative response to the still-face. These findings are discussed in the context of the development of social regulatory capacities in infancy.

Affect↗
PubMed1990

The role of dyadic affect in play and infant sex in predicting infant response to the still-face situation.

This study was designed to examine mothers' and 3-month-old infants' affect in play and infant sex as predictors of infants' response to the still-face situation. Infants who evidenced negative affect in play were likely to respond with negative displays during a subsequent still-face situation. Maternal positivity in play was positively correlated with infants' social gaze in the still-face situation. In addition, maternal positivity and infant sex significantly interacted in predicting infant affective response in the still-face situation. For girls, maternal positivity was associated with decreased expressivity. For boys, maternal positivity was associated with early positive bids, which were followed by negative bids and moderately negative affect. Finally, maternal positivity and its interaction with infant sex provide unique information beyond the carry-over effect from infant affect in play to infant response to the still-face. Results are discussed in terms of patterns of individual and joint regulation.

Affect↗
PubMed1989

Investigations of learning processes in infants.

This brief review has covered three major areas: what kinds of information can infants encode in the first 6 to 9 months and what methods are available to measure their responses; the status of memory functions in infancy; and current models of synaptogenesis, a process likely underlying the emerging cognitive processes during infancy. We can conclude that infants are capable of learning even from the first hours after birth and show a rapid increase in their capacity to recall information and use it for further learning. Furthermore, neurobiologic models of development are beginning to define a more detailed picture of crucial phases in the first months for learning processes. There are four notable omissions in the above points and in the material covered in this review. Mentioning these in this summary serves to caution the reader that there is much more to consider, and to point to other active areas of investigation of infants' cognitive capacities. These points also serve as a partial response to the questions asked in the beginning of the paper about how far we have yet to go in our understanding of infants' learning and about what may be the observational blind spots for our generation of infancy investigators. First, we have not discussed what drives learning--why infants seek actively to acquire information and seem motivated to retain that information for later use? Lipsitt points out that much of early infant behavior is based on positive and negative responses to diverse stimuli of varying degrees of attractiveness, and that the "hedonic overtones," or the amount of pleasure, involved in a stimulus situation, certainly contribute to the infant's response. Until recently, studies of social and affective development have been essentially separate from studies of cognition. Currently, the field of "social cognition" symbolizes the link between studies of basic cognitive processes and social development.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1988

A collection of 56 topics with contradictory results in case-control research.

This research was done to learn more about the frequency and characteristics of conflicting research in case-control studies. In a survey of the epidemiological and medical literature, we found 56 topics in which the results of a case-control study were in conflict with the results from other studies of the same relationship. Cancer was the associated disease for 30 of the controversial topics. We suggest that much of the disagreement may occur because a set of rigorous scientific principles has not yet been accepted to guide the design or interpretation of case-control research. Consequently, the investigator's 'judgement' is the main precaution against scientific hazards and distortions in the validity of evidence. To correct this deficiency, we propose using the principles of an experimental trial to develop the scientific standards for case-control research.

Cohort Studies↗
PubMed1985

Changing cognitive outcome in preterm infants with hyaline membrane disease.

One hundred seventy-four preterm survivors of hyaline membrane disease, born 1961 through 1971, were followed up for at least six years with serial psychological and neurological evaluations. This relatively mature population had a mean birth weight of 2,133 g and gestational age of 34.6 weeks. All children had consecutive preschool and school age psychological tests. The mean preschool test score was 91 (SD = 13) and the mean school age score was 101 (SD = 16). The ten-point difference between the mean preschool and school age test scores was significant. Perinatal variables and indexes of disease severity did not correlate with test scores. Higher test scores were correlated with higher paternal educational and employment levels. Improving test scores by school age may be due to test instruments that measure different cognitive skills and/or the diminishing effects of prematurity.

Achievement↗
PubMed1984

Hypercalcemia associated with immunoreactive parathyroid hormone in a malignant rhabdoid tumor of the kidney (rhabdoid Wilms' tumor).

Severe hypercalcemia occurred in a child with metastatic disease from a rhabdoid tumor of the kidney. Because there was no evidence of skeletal involvement by tumor, an investigation of the cause for hypercalcemia was undertaken. A greatly elevated serum concentration of immunoreactive parathyroid hormone (iPTH) was documented. This together with the observation of histologically normal parathyroid glands and the immunohistologic demonstration of parathyroid hormone within tumor cells supports the hypothesis of ectopic iPTH production by the tumor. The concurrence of an unusual metabolic complication with an infrequently encountered tumor variant is notable.

Hormones, Ectopic↗
PubMed1978

Electrical stimulation of the hypothalamus: new observations on the parameters necessary for ovulation in rats anaesthetised with pentobarbitone during the pro-oestrous "critical period".

The experiments were designed to specifiy optimal parameters of hypothalamic electrical stimulation to induce ovulation in rats anaesthetised with pentobarbitone during the "critical period" on the afternoon of pro-oestrous. We have established that duration of stimulation in the arcuate region of the hypothalamus is of greater importance than total number of pulses delivered. The minimum period of stimulation to ensure that all rats ovulated was 45 min. However, stimulation in the arcuate region did not have to be continuous throughout this period. Indeed, three 5-min bursts at 100 Hz distributed equally through 45 min always caused ovulation whereas a continuous 15-min stimulation at the same frequency was without effect. With 30 min of continuous stimulation in the arcuate region, at frequencies ranging from 10 to 100 Hz, approximately half of the rats ovulated.

Anesthesia, General↗