Event-related variations in alpha band activity during an attentional task in preadolescents: Effects of morning nutrition.

OBJECTIVE: Event-related desynchronization and synchronization (ERD/ERS) methodology was used to study interactions between nutrition, brain function, cognition and behavior in children who ate or skipped breakfast after overnight fasting. METHODS: Healthy preadolescents performed a cued visual Go/No-Go RT task after overnight fasting (Phase 1) and again (Phase 2) after eating breakfast (n=30) or continuing to fast (n=30). ERS and ERD determinations (8-10, 10-12Hz; frontal, central, parietal, occipital sites) and measures of sleep (overnight actigraphy) and blood glucose (finger sticks) were obtained. RESULTS: Feeding increased blood glucose, but the groups were similar in sleep amount and response accuracy. Between-phase comparisons showed slower RT and increased alpha synchronization in fasting subjects, but little change in those who ate breakfast. Phase 2 group differences emphasized greater frontal early ERS and late frontal-central ERD in Fed subjects. CONCLUSIONS: In preadolescents a brief extension of overnight fasting resulted in significant changes in brain activity and behavior that were effectively countered by eating breakfast. Delaying breakfast until mid-morning appeared to have introduced fasting effects that attenuated responses in Fed subjects. SIGNIFICANCE: These findings show the sensitivity of brain function and behavior to subtle variations in nutritional status and argue for greater consideration of nutritional variables in neurobehavioral studies.

Skipping breakfast: gender effects on resting heart rate measures in preadolescents.

The cardiovascular response in children to morning nutrition has received little attention, and associated gender-related effects are virtually uninvestigated. This study evaluated resting heart-rate (HR) and heart-rate variability (HRV) in preadolescents after overnight fasting and again after eating a standardized breakfast or continuing to fast. HR increased slightly after eating and decreased significantly with continued fasting. These effects were present for both sexes. Relative to children who ate, those who continued fasting showed increases in HRV-particularly for inter-beat-interval and low frequency component (LF: 0.04-0.15 Hz) measures. Analyses revealed significant increases across variability measures for fasting children, but a selective LF decrease in those who were fed-an effect most prominent in females. Otherwise, males and females showed similar treatment-related changes in HRV. While within-gender comparisons showed similar results for HR, i.e., faster HR in fed compared with fasting males and females, respectively, fasting females-but not males-showed significantly greater increases in variability relative to their fed counterparts. Together, these findings suggest that extended overnight fasting initiates an increase in parasympathetic activity that attenuates the expected increase in cardiovascular output following a mid-morning meal. Observed gender differences were related to greater parasympathetic activity in males and to the apparent emphasis on parasympathetic regulation of LF variability. The implications of these findings for health concerns, the nature of responses to physiological and cognitive stressors, and how such differences may influence performance variables-particularly early in development when cardiovascular responses to these stressors may be more sensitive to nutritional factors-are discussed.

Familial anthropophobia in pointer dogs?

This article assesses a dog model in terms of a proposed cross-species definition of phobia, the model referring to a strain of unstable dogs that has been produced by selection and inbreeding. The unstable dogs are contrasted with a strain of stable dogs. New findings are presented on approach and activity behavior toward three stimulus objects (man, another dog, and a sheet-covered chair) in a naturalistic setting. The fear response of unstable dogs to objects other than man habituates gradually, whereas the fear response to the sight of man is far more enduring, suggesting a relatively specific fear of man.

Electrocortical frequencies in hyperactive, learning-disabled, mixed, and normal children.

Ten boys in each of four groups (hyperactive, learning-disabled, hyperactive/learning-disabled or mixed, and normal) were exposed to a complex visual search task. EEGs were recorded at central and parietal sites, 1-sec prestimulus and 1-sec poststimulus onset, on three types of trials. The resulting wave forms, averaged over trials, were converted to the frequency domain via a fast Fourier transform and factored by principal components. Four components accounting for 87% of the variance were varimax-rotated. Analyses of variance of the component scores revealed that Component 1 differentiated the four groups of boys. This component had highest loadings in frequencies from 16 to 20 Hz and secondary loading in frequencies from 7 to 10 Hz. It was concluded that this multifrequency component is sensitive to parameters deficient in hyperactive and learning-disabled children.

Gender and the comparison of self and observer ratings of anxiety and depression in adolescents.

OBJECTIVE: This study assessed the influence of gender on the comparability of self and observer ratings of anxiety and depression in adolescents. METHOD: Subjects were 75 inpatient adolescents who were administered structured interviews of the revised Hamilton Rating Scales for Depression (HRSD-R) and Anxiety (HARS-R) and read the Beck Depression Inventory (BDI) and Beck Anxiety Inventory (BAI). RESULTS: All measures demonstrated adequate internal consistency and validity. The correlation between the BDI and HRSD-R was significantly higher for females than males; of 11 symptoms that overlap on the BDI and HRSD-R, observers significantly agreed with males and females in their perceptions of 5 and 11 depressive symptoms, respectively. The correlation between the BAI and HARS-R did not differ significantly for males and females. CONCLUSIONS: Results suggest that self-reports of anxiety symptoms are a valid, cost-effective alternative to anxiety observer ratings for boys and girls' self-reports of depression are comparable to depression ratings by observers. There is the need to collect self-report information from adolescent boys because they may not communicate subjective symptoms of depression, e.g., guilt, to observers.

Blink rates in schizophrenia.

In schizophrenia, blink rates are frequently elevated and the peak of the electroencephalographic alpha rhythm is often absent or of a lower frequency. Emerging evidence suggests that both blinks and the alpha rhythm may be controlled by a linked neuroanatomical circuit that begins in rostral pons and involves several subcortical structures as well as the occipital cortex. Blink-alpha abnormalities in schizophrenia further suggest that this blink-alpha neurocircuit may be a locus of the pathophysiological process of this disorder.

Cardiovascular effects of morning nutrition in preadolescents.

The cardiovascular response to eating has been extensively investigated in adults, but comparable data in children are lacking. In this investigation, heart-rate and heart-rate variability were evaluated in preadolescents during resting periods in the morning initially while participants maintained overnight fasting, and again after the participants either ate a standardized breakfast or continued fasting. Relative to the initial fasting period, heart rate (HR) increased slightly in fed participants and decreased significantly in those who continued to fast. These effects were associated with significant increases in low- (LF: 0.04-0.15 Hz; primarily sympathetic influences) and high-frequency (HF:0.15-0.5 Hz; parasympathetic influences) spectral components in fasting participants and with nonsignificant decreases in both components in fed participants. Although these HF changes are consistent with the observed heart-rate variations (i.e., increases and decreases in parasympathetic influence associated with decreased and increased HR, respectively), the LF increase with the slowing, and decrease with the acceleration of HR run counter to expected sympathetic effects on HR. The net effect of these modulations was unchanged sympathovagal balance (LF/HF) for fasting participants but a significant decrease for fed participants across recording periods. The results indicate that the continuation of overnight fasting is associated with a significant increase in parasympathetic activity that is attenuated by eating breakfast. Furthermore, the findings suggest that the parasympathetic contribution to the LF spectral component is significantly enhanced in preadolescents, and, consequently, the LF/HF ratio-generally considered to reflect sympathovagal balance-does not segregate sympathetic and parasympathetic influences in children.

An event-related potential study of older children with an early history of failure to thrive.

Elementary and junior high school children (n = 13), who were diagnosed with nonorganic failure to thrive (FTT) as infants and toddlers, were compared with a normal control group (n = 14) on visual event-related potentials (ERPs) elicited during a primed lexical decision task. Positive stimuli were real words that were identical to the priming stimuli; negative stimuli were nonpronounceable letter strings. Although the groups did not differ in word-list reading level, the former FTT group had slower reaction (decision) times and did not show ERP evidence of priming in the N400 epoch. Anterior sites yielded better separation of the real words and letter strings than posterior sites. A late anterior component between 500 msec to 650 msec poststimulus onset showed the largest condition effect for both groups. The control group had a larger negative going late anterior component to words than the FTT group. The combined reaction time and ERP findings point to less automatized word recognition in the FTT group.

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.

P300 in major depressive disorder.

This study presents evidence of differences in the P3 (P300) component of the event-related potential (ERP) between major depressed patients and normal controls. ERPs were collected to visual stimuli in a modified continuous performance task. For each subject, the peak of the P3 (also N2 and P2) component was identified for four different electrode sites and three trial types (target, background, and unexpected). P3 amplitude was significantly smaller in the depressed group to target, but not to background stimuli. P3 latency differences were for the most part nonsignificant. Recent evidence suggests that P3 amplitude may not only reflect higher level cognitive functions, but also some degree of emotional involvement for the subject. It is suggested that a decrease in task involvement could account for the smaller P3 in depressives.

Auditory ERP augmentation-reduction and methylphenidate dosage needs in attention and reading disordered children.

From their event related potentials (ERPs) to tones of four intensity levels, a sample of attention disordered and/or reading disabled children, recommended for a trial on methylphenidate, were classified as auditory augmenters or reducers. The augmenters were blindly titrated at significantly lower dosage levels than the reducers. Moreover, the ameliorative effects of the drug, as assessed by teacher ratings, were more evident in hyperactive augmenters. The children diagnosed either as hyperactive or hyperactive and reading disabled had steeper (or more augmenting) gradients than the nonhyperactive reading disabled and attention disordered subjects. The ERP (N1-P2) gradients were not consistently related to reaction time (RT) gradients to the tones or to an RT measure of nervous system sensitivity. It is suggested that ERPs index registration but not response strength, the first being largely automatic and the second purposive.

Methylphenidate effects on cognitive style and reaction time in four groups of children.

Four groups of children referred for attention disorders, learning disorders, or both were blindly titrated at statistically equivalent dosage levels of methylphenidate and improved more or less equivalently on several measures of attentiveness (cognitive style tests and reaction time). Methylphenidate dosage needs, which vary considerably, appear more strongly related to indices of nervous system sensitivity than clinical diagnosis. Interactions of stimulus intensity, reward level, and drug condition on reaction time (RT) lend credence to the theoretical constructs of augmentation-reduction and nervous system sensitivity. Order of treatment (placebo before drug or drug before placebo) had an unexpected effect on RT, suggesting that on a boring, frustrating task, methylphenidate may enhance performance less as a function of number of exposures to the experience.

Psychiatric comorbidity and response to two doses of methylphenidate in children with attention deficit disorder.

ABSTRACT In a large, heterogeneous sample (N = 182) of children with attention deficit disorder (ADD), the prevalences of additional DSM-III diagnoses were determined using the Diagnostic Interview for Children and Adolescents (DICA). More than half the children had additional DSM-III psychiatric diagnoses. Oppositional disorder and anxiety/mood disorders were the most frequent diagnoses. White male children with ADD were selected into four contrast groups based on comorbidity: ADD children with no additional diagnosis (neither), with anxiety or depression (ANX/DEP), with oppositional or conduct disorder (OPP/CON), and with both ANX/DEP and OPP/CON diagnoses (both). ADD children who had both ANX/DEP and OPP/CON were significantly more improved on a high dose (0.6 mg/kg bid) than a low dose (0.3 mg/kg bid), but ADD boys in the other diagnostic groups responded as well to both doses. There was no evidence that ADD children with comorbid emotional or disruptive behavior disorders respond any less well to psychostimulants than other ADD children. However, there is a concern for those children who have the comorbid combination of (1) ADD, (2) an additional externalizing disorder (disruptive behavior disorder), and (3) an internalizing disorder (a mood or anxiety disorder). These children may not respond to low clinical doses of psychostimulants, but may respond well at higher doses. Children's self-ratings on the DICA may provide important clinical data concerning stimulant dosing which are not provided by teacher or parent ratings. We found no evidence that ADD children with comorbid emotional disorders respond any less well to a psychostimulant than ADD children without emotional comorbidity.

Heart rate changes following habituation testing of the motor response in normal human fetuses.

We examined the heart rate (HR) response immediately following habituation testing in 54 normal human fetuses between 34 and 40 weeks of gestation to determine if cardiac self-regulation was a function of the rate of motor habituation. All fetuses received eight trials of a 1-s vibroacoustic stimulus (VAS) with a 10-s interstimulus interval. A score of 0-10 was assigned for each trial based on subjective assessment of intensity and duration of the fetal motor response. Motor habituation was evaluated in terms of the rate of response decrement over trials. For each fetus the average post-VAS HR was calculated in 1-min blocks for the first 7 min following habituation testing. When subjects were divided into slow and fast motor habituators, we found that fetuses who were slow habituators displayed a significantly greater increase in HR above baseline at each of the first 7 min following habituation testing as compared to fetuses whose motor response habituated more rapidly, F(1,52) = 4.88, P = 0.03. However, there was no difference between slow and fast motor habituators in the rate at which the HR returned toward prestimulus levels. To further examine these results, we divided the 54 fetuses into four groups based on the medians of the slope of the post-VAS HR regression line and the variability in HR about this line. We found that fetuses whose HR decreased slowly after habituation testing displayed significantly greater variability in their cardiac response as compared to fetuses whose HR decreased more rapidly (chi 2 = 4.74, P = 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

Behavioral state affects heart rate response to low-intensity sound in human fetuses.

The cardiac orienting reflex is elicited by a low-intensity sound, it consists of a sustained heart rate (HR) deceleration, and it is a specific physiological correlate of cognitive processing. In this study we examined the relationship between behavioral state and the cardiac orienting reflex in 75 human fetuses between 36 and 40 weeks gestation. Each fetus was stimulated with a 30-s speech sound at an average intensity of 83 dB SPL in quiet sleep (QS) and active sleep (AS). The fetal cardiac electrical signal was captured transabdominally at a rate of 1024 Hz and fetal R-waves were extracted using adaptive signal processing. Fetal behavioral states were assigned based on HR pattern and the presence or absence of eye and general body movements. We found that a significant HR deceleration occurred, in both QS and AS, following stimulus onset. However, HR decelerations occurred more often in QS than AS; and for fetuses exhibiting a HR deceleration, the magnitude of the deceleration was greater in AS compared to QS. In addition, in AS female fetuses exhibited a larger, more sustained HR deceleratory response than male fetuses, but the seconds x gender interaction in QS was not significant. Based on these results, we concluded that behavioral state is an important determinant of the HR deceleratory response in human fetuses.

Effects of reward and methylphenidate on heart rate response morphology of augmenting and reducing children.

In a group of attention and/or learning disordered children referred for a trial on methylphenidate, beat-to-beat analysis of heart rate (HR) to auditory stimuli showed the response to be affected by stimulus intensity, reward level, and drug condition (placebo or active). When the children were classified as augmenters or reducers on the basis of their event-related potentials to the 4 intensity levels, the reducers had significantly higher pretreatment HR response levels as well as quicker latencies to reach deceleration trough (anticipatory component) and acceleratory peak (rebound rise to the tones). The clinically titrated methylphenidate dosage levels for the subjects were related both to the augmenter-reducer classification and to pretreatment HR levels; that is, subjects who were ERP reducers and/or had higher HR levels, especially under reward conditions, were blindly titrated at higher levels than those who were augmenters and/or had lower HR levels.

Auditory event-related potentials in attention and reading disabled boys.

Event-related potentials (ERPs) were recorded from 4 groups of children: (1) reading disabled, (2) attentional deficit disorder with hyperactivity, (3) attentional deficit disorder without hyperactivity, and (4) normal controls. Subjects were instructed to press a button to a low probability tone (target, P = 0.168) and to ignore all other events which included a high probability tone (non-target, P = 0.664) and an unexpected novel sound (P = 0.168). The amplitude of several late ERP components and the latency of the P3b component were examined. As in a previously reported visual study with the same sample of children, the overall amplitude of the P3b component was significantly smaller in all the clinical groups than in controls. Two other late components (slow wave and Pc) were also smaller in the clinical groups than in controls. P3 latency did not, however, differentiate the groups.

Neuropsychological patterns in pediatric epilepsy.

Results from comprehensive neuropsychological assessments of children diagnosed with epilepsy have rarely been reported. Previous research has generally focused on the measurement of overall intellectual ability and achievement skills. In the present study, neuropsychological evaluations including memory, attention, language, achievement, fine motor, executive function, visual motor integration, and behavior were completed on children (n = 79) diagnosed with epilepsy. Neurocognitive skills were within expectations for measured intelligence with the exception of verbal and visual attention skills, which were significantly below expectations based on measured ability. Behaviorally, children were rated by their parents as demonstrating clinically elevated attentional problems. Differences in cognitive and behavioral function were not found according to seizure type. Findings suggested a more diffuse effect of childhood epilepsy reflected in a pattern of decreased attention skills.

EEG power spectra of dysphonetic and nondysphonetic poor readers.

Two subtypes of poor readers, dysphonetic and phonetic, were compared on EEG spectral values obtained as they viewed strings of letters and short words. Dysphonetic poor readers had significantly higher values than phonetics in the theta and delta bands. Both phonetic and dysphonetic poor readers had lower beta values than adequate reading children with Attention Deficit Disorder. This evidence indicates that poor readers, especially dysphonetics, were less actively engaged in the task.

Event-related brain potentials elicited during phonological processing differentiate subgroups of reading disabled adolescents.

Visual and auditory rhyme judgment tasks were administered to adolescent dyslexics and normal readers while event-related brain potentials were recorded. Reading disabled subjects were split into two groups based on a median split of scores on a visual non-word decoding test. The better decoders were called Phonetics and the poorer decoders were referred to as Dysphonetics. Single syllable, real word stimuli were used, and both rhyming and non-rhyming targets had a 50% chance for matching orthography. In the visual paradigm the normal readers exhibited a left frontal CNV before targets, a large reduction in frontal N400 for matching orthography (orthographic priming), and a large reduction in parietal N400 for rhyming targets (phonological priming). Dysphonetics had an intact CNV and orthographic priming, but the group's phonological priming was very reduced. Phonetics showed both orthographic and phonological priming but had a marked reduction in their CNV. In the auditory task, controls showed a left parietal N400 priming effect for rhyming targets. Dysphonetics showed a similar bilateral effect. The Phonetics did not show a normal priming effect, but produced evidence for priming at a longer latency. Additionally, the Phonetic group responded more slowly than either of the other two groups, who responded with similar latencies. These results support the separation of the reading disabled into a group that has difficulty translating orthography into phonology, and a group that is slower functioning and has reduced capacity in preparing for a response.