R.T. Pivik

Elevated sleep arousal thresholds in enuretic boys: clinical implications

Enuretic children are described as difficult to arouse from sleep. We studied auditory sleep arousal thresholds in enuretic boys and report on die clinical implications of these findings. Fifteen enuretic and 18 control subjects (7–12‐year‐old males) were studied in a sleep laboratory for four consecutive nights using standard polysomnographic recording techniques. Sleep was undisturbed for the initial two nights and waking thresholds were measured on the following two nights. Enuretic children wet most frequently in the first two‐thirds of the night. Arousal attempts were successful 39.7% of the time in controls and only 9.3% of the time in enuretics. In conclusion, enuretic males were more difficult to arouse than age‐matched controls. The elevated arousal thresholds may be due to delayed maturation. Treatment programmes that rely on awakening should be aware of these features.

Delta‐9‐tetrahydrocannabinol and synhexl: Effects on human sleep patterns

A series of experiments was conducted to determine the effects of orally administered 1‐trans‐Δ‐9‐ tetrahydrocannabinol (THC) on both undisturbed and experimentally altered (by rapid eye movement [REM] deprivation) sleep patterns of young adult male volunteers. In the deprivation experiments, the effects of a semisynthetic Δ‐6a‐10‐THC homologue, synhexl, were also studied. In the normative studies, 4 subjects received THC in doses ranging from 61 to 258 µg per kilogram shortly before sleep onset, while in the deprivation experiments 2 subjects received either THC (244 µg per kilogram and 259 µg per kilogram) or synhexl (733 µg per kilogram and 777 µg per kilogram) the morning after the second of 2 consecutive nights of REM deprivation. In both normative and deprivation experiments, all‐night sleep recordings were taken during base‐line, drug, and postdrug conditions. The results of both types of experiments were consistent in demonstrating increments in Stage 4 sleep and decrements in REM sleep. In the normative experiments, reduction in Stage 1 and time awake after sleep onset were observed at the highest dose level. Interpretation of these results and their relation to the effects of other psychoactive compounds upon sleep patterns are discussed.

Developmental Status of 1-Year-Old Infants Fed Breast Milk, Cow’s Milk Formula, or Soy Formula

BACKGROUND AND OBJECTIVE: Although soy formula has been reported to support normal development, concerns exist regarding potential adverse developmental effects of phytochemicals associated with soy protein. This study characterized developmental status (mental, motor, and language) of breastfed (BF), milk-based formula–fed (MF), or soy protein–based formula–fed (SF) infants during the first year of life. METHODS: Healthy infants (N = 391) were assessed longitudinally at ages 3, 6, 9, and 12 months. Development was evaluated by using the Bayley Scales of Infant Development and the Preschool Language Scale-3. Mixed effects models were used while adjusting for socioeconomic status, mother’s age and IQ, gestational age, gender, birth weight, head circumference, race, age, and diet history. RESULTS: No differences were found between formula-fed infants (MF versus SF). BF infants scored slightly higher than formula-fed infants on the Mental Developmental Index (MDI) score at ages 6 and 12 months (P < .05). Infants who were breastfed also had higher Psychomotor Development Index scores than SF infants at age 6 months and slightly higher Preschool Language Scale-3 scores than MF infants at ages 3 and 6 months (P < .05). In addition, BF infants had a lower probability to score within the lower MDI quartile compared with MF infants and a higher likelihood to score within the upper quartile for the MDI and Psychomotor Development Index compared with SF infants. CONCLUSIONS: This unique study showed that all scores on developmental testing were within established normal ranges and that MF and SF groups did not differ significantly. Furthermore, this study demonstrated a slight advantage of BF infants on cognitive development compared with formula-fed infants.

Early Infant Diet and the Omega 3 Fatty Acid DHA: Effects on Resting Cardiovascular Activity and Behavioral Development During the First Half-Year of Life

This investigation evaluated variations in resting heart rate (HR) measures during the first half year of life in healthy, full-term infants who were either breast-fed (BF), or fed formula with (milk-based: MF; soy-based: SF) or without (soy-based: SF−) commercially supplemented DHA (decosahexaenoic acid). In infants fed the DHA-deficient diet, higher HR and lower values for heart rate variability measures were observed, indicating decreased parasympathetic tone in this group. These effects, appearing at 4 months and continuing for the remainder of the study period, are consistent with suggestions that the 3–5-month postnatal interval may be an important period in the development of cardiovascular regulation. The absence of these effects in SF infants receiving the DHA-supplemented formula suggests that neither soy protein nor the associated phytochemicals in soy formula contribute to these effects to any appreciable extent. In general, the results do not indicate differences in any of the study variables attributable to soy formula per se.

Eating breakfast enhances the efficiency of neural networks engaged during mental arithmetic in school-aged children.

To determine the influence of a morning meal on complex mental functions in children (8-11 y), time-frequency analyses were applied to electroencephalographic (EEG) activity recorded while children solved simple addition problems after an overnight fast and again after having either eaten or skipped breakfast. Power of low frequency EEG activity [2 Hertz (Hz) bands in the 2-12 Hz range] was determined from recordings over frontal and parietal brain regions associated with mathematical thinking during mental calculation of correctly answered problems. Analyses were adjusted for background variables known to influence or reflect the development of mathematical skills, i.e., age and measures of math competence and math fluency. Relative to fed children, those who continued to fast showed greater power increases in upper theta (6-8 Hz) and both alpha bands (8-10 Hz; 10-12 Hz) across sites. Increased theta suggests greater demands on working memory. Increased alpha may facilitate task-essential activity by suppressing non-task-essential activity. Fasting children also had greater delta (2-4 Hz) and greater lower-theta (4-6 Hz) power in left frontal recordings-indicating a region-specific emphasis on both working memory for mental calculation (theta) and activation of processes that suppress interfering activity (delta). Fed children also showed a significant increase in correct responses while children who continued to fast did not. Taken together the findings suggest that neural network activity involved in processing numerical information is functionally enhanced and performance is improved in children who have eaten breakfast, whereas greater mental effort is required for this mathematical thinking in children who skip breakfast.

Brain gray and white matter differences in healthy normal weight and obese children

To compare brain gray and white matter development in healthy normal weight and obese children.

Failure of High Intensity Auditory Stimuli to Affect Behavioral Arousal in Children during the First Sleep Cycle

Summary: Behavioral and physiologic indices of arousal to auditory stimuli were examined during the first cycle of sleep in 8–12-year-old hyperactive children and nonhyperactive controls. No behavioral responses or sustained awakenings were obtained for any child during the first cycle of sleep to stimuli at intensities up to 123 dB sound pressure level re 0.0002 dynes/cm2), i.e., at intensities more than 90 dB above waking threshold values. Half of the arousal attempts in stage 2 and a quarter of those in stage 4 elicited a partial or momentary physiologic arousal response (i.e., EEG desynchronization and/or change in skin potential response or respiratory activity rates). These arousals were shortlived, with the subjects returning to sleep even with continuing or increased stimulus intensity. Neither the incidence of partial arousals nor the associated threshold intensities differentiated subject groups. Although increased skin potential response activity and decreased respiratory rates were observed during sleep relative to wakefulness, and a predominance of skin potential response activity was noted in stage 4 sleep, no significant differences in frequency (rate/min) of autonomic response measures were obtained when rates before and during auditory stimulation were compared.

A longitudinal study of differences in electroencephalographic activity among breastfed, milk formula-fed, and soy formula-fed infants during the first year of life.

BACKGROUND The extent to which adequate nutrition from infant diets differentially influence developmental outcomes in healthy infants has not been determined. AIM To compare the effects of the major infant diets on the development of brain electrical activity during infancy. STUDY DESIGN Scalp EEG signals (124 sites) recorded from the same infants during quiet wakefulness at 3, 6, 9, and 12months. SUBJECTS Healthy, full-term infants (40/group; gender matched) either breastfed (BF) or fed milk formula (MF) or soy formula (SF) through the first 6months. OUTCOME MEASURES Power spectral values for frequencies in the 0.1-30Hz range. RESULTS Significant diet-related differences were present across frequency bands and included effects that were time- [peaks in 0.1-3Hz at 6 (MF,SF) and 9months (BF); 3-6Hz at 6months (MF, SF>BF); increases in 6-9Hz from 3 to 6months (MF>BF) and from 6 to 9months (MF>SF)] and gender-related (9-12Hz and 12-30Hz: at 9months BF>MF, SF boys, and MF>SF girls). CONCLUSIONS The development of brain electrical activity during infancy differs between those who are breastfed compared with those fed either milk or soy formula, but is generally similar for formula-fed groups. These variations in EEG activity reflect diet-related influences on the development of brain structure and function that could put infants on different neurodevelopmental trajectories along which cognitive and brain function development will proceed.

Endogenous eye blinks in preadolescents: relationship to information processing and performance

Endogenous blinks--those occurring without apparent provocation--are regulated in adults with respect to the presentation, cognitive loading, and response demands of stimuli. This investigation determined the extent to which similar regulatory and response-related relationships were evident in preadolescents during a visual continuous performance task (CPT). As in adults, increased blink incidence on task, longer blink deferral following stimuli with greater cognitive loading, and blink-facilitated motor responses to imperative stimuli were observed. Reaction times significantly decreased when the button press (BP) occurred near (+/- 200 ms) blink onset and increased across the task period on blink-free but not blink-associated trials. More blinks occurred before motor responses in females, and a reaction time (RT) advantage for males on blink-free trials was maintained across blink-associated conditions. From these results, an interpretation is developed arguing that endogenous blinks are a meaningful and integral component of sensory-motor processing, indexing times of facilitated attentional and motor response capability.

Sleep-wakefulness rhythms in the rabbit.

The characteristics and stability of sleep-wakefulness patterns across consecutive 24-h periods were examined in adult male rabbits implanted for chronic recording of electroencephalographic, eye movement, and nuchal muscle activities. Criteria for stage scoring along with associated scoring reliability are presented. Rabbits slept an average of 11.4 h per day, 25.9% of which was drowsy, 64.5% slow wave sleep, and 9.6% paradoxical sleep. Diurnal differences in amount and type of sleep, consisting of increased wakefulness and decreased paradoxical sleep during the dark phase of the light-dark cycle, were observed. The results are integrated with those of previous sleep studies in this species and phylogenetic implications of variations in the distribution and characteristics of sleep in the rabbit are discussed.