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Biomedical subjects

L A Tucker

Publications and source records attributed to L A Tucker.

At least 19 recordsLinked to original sources
PubMed2001

Recording and analyzing high-density event-related potentials with infants. Using the Geodesic sensor net.

This article provides an overview of the use of the Geodesic sensor net system for high-density event-related potential (ERP) recording in infants. Some advantages and disadvantages of the system, as applied to infants, are discussed. First, we illustrate that high-density data can be recorded from infants at comparable quality to that observed with conventional (low density) ERP methods. Second, we discuss ways to utilize the greater spatial information available by applying source separation and localization procedures. In particular, we focus on the application of one recent source separation method, Independent Component Analysis (ICA). Finally, we show that source localization can be applied to infant high-density data, although this entails adopting a number of assumptions that remain to be verified. In the future, with improved source separation algorithms, we suggest that single-trial or single-subject analyses may become feasible.

Adult↗
PubMed2000

Cortical development and saccade planning: the ontogeny of the spike potential.

The spike potential is a sharply timed positivity which precedes eye movements in adults, and is thought to indicate cortical planning of saccades. While the spike potential is observed under most conditions in adults, it has not been reported in young infants. In the present study we shed light on the ontogeny of the spike potential by demonstrating for the first time its existence in a group of older infants (12 months). This result is consistent with a relatively delayed onset of cortical control over saccades during development.

Age Factors↗
PubMed1998

Neural correlates of saccade planning in infants: a high-density ERP study.

Neural correlates of saccade planning in 6-month-old infants were investigated by high-density event-related potentials. Subjects made saccades to a target stimulus following a time gap from fixation stimulus offset (gap trials) or with the fixation stimulus still present (overlap trials). Like adults, infants were slower to make a saccade to the target when the fixation stimulus was still present. Strikingly, infants did not show clear evidence of the pre-saccadic components observed in adults which are thought to reflect cortical saccade planning processes. They did, however, show a left frontal positivity, which we suggest reflects cortical disinhibition of the colliculus initiated by fixation stimulus offset, and clear post-saccadic lambda waves. These results indicate that the frontal cortex already plays a role in action control by 6 months of age, while other aspects of cortical action planning may not yet be present in certain task situations.

Electroencephalography↗
PubMed1997

Body fat percentage of children varies according to their diet composition.

OBJECTIVE: To ascertain the association between diet composition and body fat percentage in 9- and 10-year-old children. Also, to examine the influence of gender, total energy intake, fitness, physical activity, and parental body mass on the relationship between diet composition and adiposity. DESIGN: Diet composition was assessed using the National Cancer Institute food frequency questionnaire, and adiposity was measured using the average of results determined using two skinfold equations. Fitness levels and physical activity were ascertained using the 1-mile run/walk test and a self-report 15-item scale, respectively. SUBJECTS: A sample of 262 children (162 boys and 100 girls, mean age = 9.8 +/- 0.5 years) participated. STATISTICAL ANALYSIS: Regression analysis was used to determine the extent to which diet composition contributed to adiposity without statistical control for any potentially confounding variables. Partial correlations were calculated to assess the relationship between macronutrient intake and adiposity after potential confounders (gender, total energy intake, physical fitness, and parental body mass) were controlled statistically. RESULTS: Energy intake was positively related to adiposity. Fat intake, calculated as a percentage of total energy, was also positively related to adiposity, before and after control for potential confounding variables. Percentage of energy derived from carbohydrate was inversely related to adiposity, before and after controlling for potential confounders. APPLICATIONS: These findings indicate that the macronutrient intake of children, particularly dietary fat and carbohydrate intake, may play a role in adiposity, independent of the influence of total energy intake, gender, physical fitness, and parental body mass index.

Adipose Tissue↗
PubMed1997

Attention and oculomotor control: a high-density ERP study of the gap effect.

In a gap paradigm, healthy adult subjects performed visually triggered saccades to peripheral targets either with the fixation stimulus remaining on (overlap trials) or going off before target onset (gap trials). All subjects showed faster reaction times in the gap trials (the gap effect). High density scalp event-related potentials were recorded time-locked to both the target stimuli and the eye movement onset. We observed three neural correlates of the gap effect: (i) a prefrontal positivity that precedes the target presentation which may reflect specific preparatory processes, (ii) an enhancement of the early cortical visual responses (PI) to the peripheral target in the gap trials, and (iii) a prolongation of parietal activity in the overlap trials relative to the gap trials prior to the saccade execution. These results suggest that several factors contribute to the gap effect, each having its own neural basis.

Adult↗
PubMed1996

The development and temporal dynamics of spatial orienting in infants.

Shifts of visual attention can be studied in adults by cueing a particular spatial location and assessing the speed of detection of targets presented in the cued location as compared to other locations. A number of studies have used spatial cueing paradigms in an attempt to study attention shifts in infants. However, these studies have employed different procedures, time courses, measures, and age groups, making comparison between them difficult. The present experiments were designed to investigate the effects of varying the cue-target time interval on the speed and direction of orienting in 2-, 4-, and 6-month-old infants. The results of Experiment 1 indicated that, while 2-month-old infants showed only weak effects of the cue, 4-month-old infants show facilitation to a cued location when a target appears 200 ms after cue onset, and inhibition of responses to the same location when the target appears 700 ms after the cue onset. Six-month-old infants showed evidence of inhibition, but not facilitation. One account of this pattern of data is that 6-month-olds shift attention faster than do 4-month-olds. This hypothesis was tested in Experiment 2 in which four different cue-target intervals were used with a group of 7-month-old infants. The results obtained were consistent with the hypothesis that infants get faster to shift attention to a spatial location with age.

Age Factors↗
PubMed1996

Diet composition related to body fat in a multivariate study of 203 men.

OBJECTIVE: To assess whether usual diet (especially intake of dietary fat, carbohydrate, and fiber) was related to body fat percentage in healthy men. DESIGN: A written questionnaire provided data on demographic and lifestyle characteristics. Dietary fat, carbohydrate, protein, and fiber intakes were analyzed using the National Cancer Institute food frequency questionnaire. Percentage of body fat was determined using three-site skinfold measurements, and a submaximal treadmill test was used to estimate aerobic fitness. SUBJECTS: Subjects were 203 healthy men (14.0 +/- 5.3% mean body fat) aged 21 to 71 years. The subjects were chosen from randomly selected districts within Utah County and volunteered for free diet and fitness evaluations. STATISTICAL ANALYSIS: Multiple regression analysis determined the extent to which the individual diet components predicted body composition before and after controlling for energy intake, fitness level, body weight, and age. Multivariate analysis of variance was used to compare relative body fat groups in regard to dietary variables. RESULTS: Reported intakes of carbohydrate (P = .0085, R2 = .022), complex carbohydrate (P = .0127, R2 = .024), and fiber (P = .002, R2 = .03) were inversely associated with body fat after controlling for age, energy intake, and fitness level. Energy intake was positively related to body fat after controlling for age, fitness level, and body weight. When subjects were separated into low-, moderate-, and high-body-fat groups, the fattest subjects reported eating significantly more dietary fat (P = .05) and less carbohydrate (P = .01), complex carbohydrate (P = .01), and fiber (P = .005) than the leanest subjects. No significant difference in reported energy intake was noted across body fat groups. APPLICATIONS: Composition of the diet may play a role in obesity beyond energy intake in men over the long-term. Lifestyle changes for men should probably include modifications in diet composition, especially increased consumption of foods high in complex carbohydrate and fiber.

Adipose Tissue↗
PubMed1996

Comparison of the CardioGlide, CrossWalk, and treadmill walking in development of cardiovascular endurance, dynamic strength, and flexibility in middle-aged men and women.

The purpose of this study was to estimate association of exercise on the CardioGlide, CrossWalk, or treadmill with changes in cardiovascular endurance, dynamic strength, and flexibility and to ascertain if there was any advantage of training with one type of equipment compared to the others. 67 sedentary men and women participated. Fitness components were assessed at baseline and following the intervention. Subjects trained three days per week increasing exercise duration and intensity to 30 minutes at 80% of age-predicted maximum heart rate. Analysis showed that training was associated with significant improvements in all of the measured components of fitness; however, there was no advantage to using one exercise machine over the others.

Adult↗
PubMed1996

Television viewing and muscular fitness of children.

The findings of this study indicate there is no significant relationship between time spent watching TV and measured muscular fitness (pullups, pushups, and situps) in 262 9- and 10-yr.-old boys and girls. Apparently, frequent TV viewing is not detrimental to the muscular fitness of children this age.

Child↗
PubMed1995

Aerobic fitness, blood lipids, and body fat in children.

This study examined the association between aerobic fitness and serum cholesterol and the effects of controlling for gender, body composition, abdominal fat, and dietary saturated fat in 262 children. The 1-mile run was used to estimate fitness. Skinfolds were used in assessing body fat. Fit children had lower total cholesterol, low-density lipoprotein cholesterol, and triglyceride levels and higher high-density lipoprotein cholesterol levels than unfit children, except after adjustment for body fat and/or abdominal fat. Unfit children appear to be at an increased risk of unhealthy levels of serum cholesterol due primarily to increased levels of body fat.

Body Composition↗
PubMed1994

Psychosocial discomfort and exercise frequency: an epidemiological study of adolescents.

This study sought to determine the extent to which adolescents (N = 1,297) who report different levels of physical exercise vary with respect to selected indicators of psychosocial discomfort. Results indicated that those who exercise infrequently suffer more from loneliness, shyness, and hopelessness than do adolescents who exercise more frequently. The potential confounding effects of gender, grade level, perceived attractiveness, body mass, and weight satisfaction were statistically controlled. Potential explanations for the observed relationships between frequency of exercise and psychosocial discomfort and implications for fitness, recreation, and health professionals are presented.

Adaptation, Psychological↗
PubMed1993

Post-pump delirium.

Cardiac surgery has many associated complications but the psychological problems that can occur are rarely discussed. This literature review focuses on both the physiological and psychological causes of post-pump delirium and suggests possible recommendations for nursing practice.

Adult↗
PubMed1992

Dietary fat and body fat: a multivariate study of 205 adult females.

This study examined the association between diet composition, particularly dietary fat intake, and body-fat percentage in 205 adult females. Subjects completed a written questionnaire regarding lifestyle factors, such as exercise participation and smoking, demographic data, and the diet section of the National Cancer Institute's Health Habits and History Questionnaire by Block. Skinfold-thickness measures were used to ascertain the body-fat percentage of each subject. Results showed that intake of dietary fat was related significantly with adiposity, without (F = 13.65, R2 = 0.063, P = 0.0003) and with (F = 8.74, R2 = 0.033, P = 0.0035) control for multiple potential confounding factors: age, total energy intake, total exercise time per week, years of regular physical activity, consumption of other macronutrients, and smoking. Unlike dietary fat intake, protein consumption and carbohydrate intake were not significant individual predictors of body-fat percentage when the potential confounding variables were controlled. The findings suggest that dietary fat intake may play a role in obesity beyond dietary energy content.

Adipose Tissue↗
PubMed1991

Television viewing and obesity in adult females.

We measured the relation between time spent watching television per week and obesity in 4,771 adult females. After controlling for age, education, cigarette smoking, length of work week, and weekly duration of exercise, females who reported three to four hours of TV viewing per day showed almost twice the prevalence of obesity (body fat greater than 30 percent), and those who reported more than four hours of TV watching per day showed more than double the prevalence of obesity, compared to the reference group (less than 1 hr/day). Part of the TV/obesity association was a function of differences in exercise duration among the four TV viewing categories.

Adipose Tissue↗
PubMed1990

Television viewing and physical fitness in adults.

The purpose of this study was to determine the extent to which time spent watching television is associated with cardiovascular fitness among 8,885 adults. Potential confounding effects of age, gender, smoking, length of work week, time reported exercising each week, and obesity were also examined. Subjects who watched TV more than 4 hours per day (frequent viewers) were 0.37 times as likely to be physically fit as those who watched TV less than 1 hour per day (infrequent viewers) with age and gender controlled. Similarly, adults who watched TV 3-4 hours per day (moderately frequent viewers) were 0.45 times as likely to be fit as infrequent watchers. Adjustment for potential confounders, particularly measured body fat and reported exercise duration in combination, weakened the TV viewing/fitness relation moderately. Given the findings of this study and the results of previous research, caution should be exercised regarding excessive television viewing.

Adult↗
PubMed1990

Walking and serum cholesterol in adults.

We measured the association between walking for exercise and the ratio of total cholesterol/HDL cholesterol in 3,621 adults. After controlling for age, gender, income, body fat, alcohol use, exercise other than walking, and cigarette smoking, adults in the high, moderate, and low duration walking categories were compared to those in the no walking-no exercise category. The relative risk for total/HDL ratios of 5.0 or more were .46 (95% CI = .27, .80), .48 (95% total/HDL ratios of 5.0 or more were .46 (95% CI = .27, .80), .48 (95% CI = .30, .76), and 1.11 (95% CI = .81, 1.53) respectively.

Adult↗