Differences in brain functional connectivity at resting state in neonates born to healthy obese or normal-weight mothers.

Recent studies have shown associations between maternal obesity at pre- or early pregnancy and long-term neurodevelopment in children, suggesting in utero effects of maternal obesity on offspring brain development. In this study, we examined whether brain functional connectivity to the prefrontal lobe network is different in newborns from normal-weight or obese mothers. Thirty-four full-term healthy infants from uncomplicated pregnancies were included, with 18 born to normal-weight and 16 born to obese mothers. Two weeks after delivery, the infants underwent an magnetic resonance imaging (MRI) examination during natural sleep, which included structural imaging and resting-state functional MRI (fMRI) scans. Independent component analysis was used to identify the prefrontal lobe network, and dual regression was used to compare functional connectivity between groups. Infants born to normal-weight mothers had higher recruiting (P<0.05, corrected) of dorsal anterior cingulate cortex regions to the prefrontal network after adjusting for maternal intelligence quotient, gestational weight gain and infant postmenstrual age, gender, birth weight/length, head circumference and neonatal diet. The functional connectivity strength in dorsal anterior cingulate cortex negatively correlated (P<0.05) with maternal fat mass percentage measured at early pregnancy. This preliminary study indicates that exposure to maternal obesity in utero may be associated with changes in resting-state functional connectivity in the newborn offspring's brain.

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

PURPOSE: To compare brain gray and white matter development in healthy normal weight and obese children. METHODS: Twenty-four healthy 8- to 10-year-old children whose body mass index was either <75(th) percentile (normal weight) or >95(th) percentile (obese) completed an MRI examination which included T1-weighted three-dimensional structural imaging and diffusion tensor imaging (DTI). Voxel-based morphometry was used to compare the regional gray and white matter between the normal weight and obese children, and tract-based spatial statistics was used to compare the water diffusion parameters in the white matter between groups. RESULTS: Compared with normal weight children, obese children had significant (P < 0.05, family wise error corrected) regional gray matter reduction in the right middle temporal gyrus, left and right thalami, left superior parietal gyrus, left pre/postcentral gyri, and left cerebellum. Obese children also had higher white matter (P < 0.05, corrected) in multiple regions in the brain and higher DTI measured fractional anisotropy (FA) values (P < 0.05, corrected) in part of the left brain association and projection fibers. There was no difference in mean diffusivity at P < 0.05, corrected. DTI eigenvalues suggested that the FA differences were likely from decreased radial diffusivity (P < 0.1, corrected) and there was no change in axial diffusivity (corrected P > 0.35 for all voxels). CONCLUSION: Our results indicated that obese but otherwise healthy children have different regional gray and white matter development in the brain and differences in white matter microstructures compared with healthy normal weight children.

Sex-specific association between infant diet and white matter integrity in 8-y-old children.

BACKGROUND: The American Academy of Pediatrics recommends breastfeeding, which is well known to promote cognitive and behavioral development. The evidence for why this occurs is not well understood. METHODS: Fifty-six 7.5- to 8.5-y-old healthy children were breastfed (BF; n = 22, 10 males) or formula-fed (FF; n = 34, 16 males) as infants. All children were administered: the Reynolds Intellectual Assessment Scale (RIAS); the Clinical Evaluation of Language Fundamentals (CELF-4) tests; and magnetic resonance imaging of the brain. Diffusion tensor imaging (DTI) measured fractional anisotropy (FA) values were correlated with RIAS and CELF-4 scores. RESULTS: DTI tract-based spatial statistics (TBSS) analyses showed multiple white matter regions in the left hemisphere with significantly higher FA (P < 0.05, corrected) values in BF than FF males, but no significant group differences in females. Males who were exclusively BF for at least 1 y appeared to have the greatest differences in FA. Mean FA values positively correlated with composite scores of RIAS (P = 0.03) and CELF-4 (P = 0.02). CONCLUSION: Breastfeeding during infancy was associated with better white matter development at 8 y of age in boys. A similar association was not observed in girls.

Diet and gender influences on processing and discrimination of speech sounds in 3- and 6-month-old infants: a developmental ERP study.

Early post-natal nutrition influences later development, but there are no studies comparing brain function in healthy infants as a function of dietary intake even though the major infant diets differ significantly in nutrient composition. We studied brain responses (event-related potentials; ERPs) to speech sounds for infants who were fed either breast milk (BF), milk-based formula (MF), or soy formula (SF) during the first 6 months of life. Two syllables presented in an oddball paradigm elicited a late positive wave (P350) from temporal and frontal brain regions involved in language processes. All groups showed significantly greater response amplitudes to the infrequent syllable across sites at 3 months and frontally at 6 months, but significant discrimination at temporal sites was only observed at 6 months in BF infants. Decreases in response amplitudes from 3 to 6 months were greater for the frequently presented syllable, most prominent in BF infants, and greater in females than males. The results indicate greater syllable discrimination in BF than formula-fed infants, but whether this can be attributed to dietary influences alone remains unclear. Feeding method and background factor differences between breastfed and formula-fed infants may also contribute to the observed differences. The general absence of differences between formula-fed groups is notable and suggests that milk-based formula and soy formula equally support brain development and function during the first post-natal 6 months. Finally, the results indicate gender differences in the development of neural and temporal processes involved in sensory discrimination, and suggest that at 6 months these processes are better developed in females.

Resting gamma power during the postnatal critical period for GABAergic system development is modulated by infant diet and sex.

Gamma band activity (30-50 Hz) plays an essential role in brain development and function, but neither the early postnatal development nor subject and environmental factors influencing this development have been reported. We documented the development of resting gamma power using high density EEG recordings obtained each month from postnatal month 2 to 6 in 518 healthy infants who were breast-fed (170; 85 boys), fed milk formula (186; 97 boys), or fed soy formula (162; 90 boys). Gamma power was determined for 44 sites distributed over major brain regions and analyses were adjusted for background variables relevant to neurodevelopment. The results show gamma power follows a gradually increasing function across this time period that varies in topographic magnitude and is differentially influenced by subject and environmental variables-among which gestation, head circumference, and infant diet-sex interactions figure most prominently. Relationships between gamma power and standardized measures of infant behavioral development appear to be emerging but are in flux during this time. Since this postnatal period is considered critical in the development of the GABAergic system underlying the generation of gamma activity, the observed findings may reflect organizational changes that will influence the future development of gamma-related behavioral and neurocognitive functions.

Cesarean Delivery Impacts Infant Brain Development.

BACKGROUND AND PURPOSE: The cesarean delivery rate has increased globally in the past few decades. Neurodevelopmental outcomes associated with cesarean delivery are still unclear. This study investigated whether cesarean delivery has any effect on the brain development of offspring. MATERIALS AND METHODS: A total of 306 healthy children were studied retrospectively. We included 3 cohorts: 2-week-old neonates (cohort 1, n = 32/11 for vaginal delivery/cesarean delivery) and 8-year-old children (cohort 2, n = 37/23 for vaginal delivery/cesarean delivery) studied at Arkansas Children's Hospital, and a longitudinal cohort of 3-month to 5-year-old children (cohort 3, n = 164/39 for vaginal delivery/cesarean delivery) studied independently at Brown University. Diffusion tensor imaging, myelin water fraction imaging, voxel-based morphometry, and/or resting-state fMRI data were analyzed to evaluate white matter integrity, myelination, gray matter volume, and/or functional connectivity, respectively. RESULTS: While not all MR imaging techniques were shared across the institutions/cohorts, post hoc analyses showed similar results of potential effects of cesarean delivery. The cesarean delivery group in cohort 1 showed significantly lower white matter development in widespread brain regions and significantly lower functional connectivity in the brain default mode network, controlled for a number of potential confounders. No group differences were found in cohort 2 in white matter integrity or gray matter volume. Cohort 3 had significantly different trajectories of white matter myelination between groups, with those born by cesarean delivery having reduced myelin in infancy but normalizing with age. CONCLUSIONS: Cesarean delivery may influence infant brain development. The impact may be transient because similar effects were not observed in older children. Further prospective and longitudinal studies may be needed to confirm these novel findings.

No difference indicated in electroencephalographic power spectral analysis in 3- and 6-month-old infants fed soy- or milk-based formula.

Increasing concern has been recently raised on the possible effects of soy-derived phyto-oestrogens on the development of cognitive functions in infants. However, limited studies have been conducted to date, and no data have been made available for determining whether infant soy formula can affect normal development of the human brain. We compared electroencephalographic (EEG) spectral power derived from high-density recordings of infants fed milk-based or soy formula (46 fed milk-based formula and 39 fed soy formula) at 3 and 6 months of age. The spectral parameters included absolute power, relative power and spectral edge frequency (SEF) at 85%, 90% and 95% levels. The frequency domain contained four bands (0.1-3, 3-6, 6-9 and 9-12 Hz). EEG signals were collected from eight brain areas in each hemisphere. The results showed that the highest spectral power was mainly distributed in the low-frequency bands and was predominant in the frontal and anterior temporal areas. None of the spectral variables significantly differed between the soy- and milk-fed infants (anova, all P > 0.2). However, significant effects were indicated on the SEFs for factors of sex, age and brain area (all P < 0.01). Hemispheric differences in the absolute and relative power were also indicated. Our results suggest that the EEG power spectral development of soy-fed infants does not differ from that of infants fed milk-based formula. In addition, EEG spectral development appears more advanced in female than in male infants at 6 months.

Brain activation to high-calorie food images in healthy normal weight and obese children: a fMRI study.

BACKGROUND: Understanding how normal weight and obese young children process high-calorie food stimuli may provide information relevant to the neurobiology of eating behavior contributing to childhood obesity. In this study, we used fMRI to evaluate whether brain activation to high-calorie food images differs between normal weight and obese young children. METHODS: Brain activation maps in response to high-calorie food images and non-food images for 22 healthy, 8-10-years-old children (N = 11/11 for normal weight/obese respectively) were generated and compared between groups. RESULTS: When comparing brain activation differences in response to viewing high-calorie food versus non-food images between normal weight and obese children, group differences were observed in areas related to memory and cognitive control. Specifically, normal weight children showed higher activation of posterior parahippocampal gyri (PPHG) and dorsomedial prefrontal cortex (DMPFC). Further ROI analyses indicated higher activation strength (Z scores) in the right PPHG (p = 0.01) and higher activation strength (p < 0.001) as well as a larger activation area (p = 0.02) in the DMPFC in normal weight than obese children. CONCLUSIONS: Normal weight and obese children process high-calorie food stimuli differently even from a young age. Normal weight children exhibit increased brain activation in regions associated with memory and cognitive control when viewing high-calorie food images.

Environmental Forces that Shape Early Development: What We Know and Still Need to Know.

Understanding health requires more than knowledge of the genome. Environmental factors regulate gene function through epigenetics. Collectively, environmental exposures have been called the "exposome." Caregivers are instrumental in shaping exposures in a child's initial years. Maternal dietary patterns, physical activity, degree of weight gain, and body composition while pregnant will influence not only fetal growth, but also the infant's metabolic response to nutrients and energy. Maternal over- or underweight, excess caloric intake, nutrient imbalances, glucose dysregulation, and presence of chronic inflammatory states have been shown to establish risk for many later chronic diseases. During the period from birth to age 3 y, when the infant's metabolic rate is high and synaptogenesis and myelination of the brain are occurring extremely rapidly, the infant is especially prone to damaging effects from nutrient imbalances. During this period, the infant changes from a purely milk-based diet to one including a wide variety of foods. The process, timing, quality, and ultimate dietary pattern acquired are a direct outcome of the caregiver-infant feeding relationship, with potentially lifelong consequences. More research on how meal time interactions shape food acceptance is needed to avoid eating patterns that augment existing disease risk. Traditional clinical trials in nutrition, meant to isolate single factors for study, are inadequate to study the highly interconnected realm of environment-gene interactions in early life. Novel technologies are being used to gather broad exposure data on disparate populations, employing pioneering statistical approaches and correlations applied specifically to the individual, based on their genetic make-up and unique environmental experiences.

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.

The influence of infant diet on early developmental changes in processing human voice speech stimuli: ERP variations in breast and milk formula-fed infants at 3 and 6 months after birth.

The purpose of this investigation was to determine if processing of language stimuli during the first half year of life in breast-fed infants differs from that of formula-fed infants. This question was addressed by examining the brain event-related potentials of healthy infants receiving breast milk (n = 15) or milk-based formula (n = 18) recorded in response to consonant vowel syllables presented in an oddball paradigm. The same infants were studied when they were 3-months and 6-months-old. The two groups were comparable on several measures relating to biological and home environment variables previously reported to influence development, including gestation period, birth weight, mother's IQ, and family socioeconomic status, and did not differ in weight or mental or motor development at the times of the visits. In general, ERP response features previously documented in studies of syllable processing in 3-6-month-old infants were observed in this study, including positive components at asymptotically equal to 190 msec (P1), asymptotically equal to 370 msec (P2), and asymptotically equal to 600 msec (P600), and negative components at asymptotically equal to 250 msec (N250), asymptotically equal to 450 msec (N450), and a late, negative going slow wave between 655 and 995 msec (LSW). For both groups there were instances where specific components were either poorly defined, e.g., P1 and N250 to the infrequent syllable at 3 months, N450 and P600 to this syllable at both ages, or not present in many infants, e.g., the P600 to the frequent syllable at 6 months. These variations appeared to be related to individual differences in development or paradigm-related features, i.e., ISI and frequency of syllable occurrence.

Effects of breast milk and milk formula diets on synthesized speech sound-induced event-related potentials in 3- and 6-month-old infants.

Effects of breast milk and milk formula supplemented with docosahexaenoic acid and arachidonic acid on speech processing were investigated by recording event-related potentials (ERPs) to synthesized /pa/ and /ba/ (oddball paradigm, 80%:20%) at 3 and 6 months of age. Behavioral assessment was also obtained. A major positive component (P200) was elicited by both types of sounds. It had a maximal scalp distribution in the fronto-central areas in both groups of infants. The mean latencies did not differ between the groups or between the stimulus types. However, the latencies decreased across age in both groups. The mean P200 amplitude in the formula-fed infants was lower than that in the breast-fed infants, but the difference was not significant. The between-stimulus differences in frontal P200 amplitudes were positively correlated with the behavioral scores of Bayley Index of Infant Development. These data suggest that the processing of the present speech stimuli is not affected by the investigated diets in the early infancy.

Growth status related to brain responses, nutrition, home environment, and behavior in infants and toddlers.

To investigate whether growth status in infants and toddlers affects processes involved in speech perception and discrimination, cortical event-related potentials (ERPs) to consonant-vowel syllables were recorded from 48 healthy babies: 26 low in growth status (LGS, < 25 th percentile in growth measures) and from 22 normal in growth status (NGS, 25t--75 th percentile in growth measures). Food records indicated no significant differences in the amounts of various nutrients consumed in the two groups, but LGS babies consumed slightly more of most nutrients than NGS babies. In response to speech stimuli (either /pa/ or /ba/ presented with 20 and 80% randomized occurrence), brain ERPs showed two prominent post-stimulus components: a large positive wave peaking at about 484 msec and a negative but positive going slow wave (SW) between 867 and 1199 msec. Principal components analysis followed by promax rotation revealed four additional important components. Maximum peak and latency values-for these components showed that NGS and LGS babies differed from one another on all measures in either amplitude, latency, or both. Comparing the two groups of babies, only the LGS group demonstrated a deficit in the phonetic discrimination of speech sounds. The growth deficiencies of the LGS group could not be attributed to the lack of an adequate diet. These negative findings are present in babies generally considered to be healthy (lowest 10-25% in growth measures). This underscores the need for research examining in more detail the relationship between growth status and cognitive growth.

Gestational Age at Birth and Brain White Matter Development in Term-Born Infants and Children.

BACKGROUND AND PURPOSE: Studies on infants and children born preterm have shown that adequate gestational length is critical for brain white matter development. Less is known regarding how variations in gestational age at birth in term infants and children affect white matter development, which was evaluated in this study. MATERIALS AND METHODS: Using DTI tract-based spatial statistics methods, we evaluated white matter microstructures in 2 groups of term-born (≥37 weeks of gestation) healthy subjects: 2-week-old infants (n = 44) and 8-year-old children (n = 63). DTI parameters including fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity were calculated by voxelwise and ROI methods and were correlated with gestational age at birth, with potential confounding factors such as postnatal age and sex controlled. RESULTS: Fractional anisotropy values, which are markers for white matter microstructural integrity, positively correlated (P < .05, corrected) with gestational age at birth in most major white matter tracts/regions for the term infants. Mean diffusivity values, which are measures of water diffusivities in the brain, and axial and radial diffusivity values, which are markers for axonal growth and myelination, respectively, negatively correlated (P < .05, corrected) with gestational age at birth in all major white matter tracts/regions excluding the body and splenium of the corpus callosum for the term infants. No significant correlations with gestational age were observed for any tracts/regions for the term-born 8-year-old children. CONCLUSIONS: Our results indicate that longer gestation during the normal term period is associated with significantly greater infant white matter development (as reflected by higher fractional anisotropy and lower mean diffusivity, axial diffusivity, and radial diffusivity values); however, similar associations were not observable in later childhood.

A new scaling method for topographical comparisons of event-related potentials.

Recent studies have demonstrated that comparisons of scalp topographical distributions of event-related potentials (ERPs) between experiment conditions may not correctly indicate underlying changes in neural sources if the signals are not scaled prior to the comparisons. This important issue was re-evaluated in this paper using both simulated and experimental data. Simulated data were generated according to 16 different brain models containing 2-4 dipole sources varying in strength, orientation, origin and number. The changes made in the strength, orientation and origin included relative changes between the sources or symmetrical changes in the sources. Experimental data were ERPs collected from 45 infants at 3 months of age. Influences of linked-ear and average references were examined. A scaling method based on relations of signal amplitudes between conditions was devised and compared with the vector method (McCarthy and Wood, 1985). While real topographic differences generated by complex changes in underlying sources were preserved, interactions between condition and electrode site due to mere strength changes were successfully identified by the new method, irrespective of reference method used. However, the vector method was not always reliable because failure to differentiate or mistakenly indicate changes in sources may occur when a linked-mastoid reference was used. The method presented in this paper is reliable and recommended prior to topographic comparisons to distinguish different types of changes in underlying neural sources.

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.

Infant Diet-Related Changes in Syllable Processing Between 4 and 5 Months: Implications for Developing Native Language Sensitivity.

Since maturational processes triggering increased attunement to native language features in early infancy are sensitive to dietary factors, infant-diet related differences in brain processing of native-language speech stimuli might indicate variations in the onset of this tuning process. We measured cortical responses (ERPs) to syllables in 4 and 5 month old infants fed breast milk, milk formula, or soy formula and found syllable discrimination (P350) and syntactic-related functions (P600) but not syllable perception (P170) varied by diet, but not gender or background measures. The results suggest breastfed and formula-fed infants differ in onset of this critical period in speech perception.

Voxel-Based Morphometry and fMRI Revealed Differences in Brain Gray Matter in Breastfed and Milk Formula-Fed Children.

BACKGROUND AND PURPOSE: Infant diets may have significant impact on brain development in children. The aim of this study was to evaluate brain gray matter structure and function in 8-year-old children who were predominantly breastfed or fed cow's milk formula as infants. MATERIALS AND METHODS: Forty-two healthy children (breastfed: n = 22, 10 boys and 12 girls; cow's milk formula: n = 20, 10 boys and 10 girls) were studied by using structural MR imaging (3D T1-weighted imaging) and blood oxygen level-dependent fMRI (while performing tasks involving visual perception and language functions). They were also administered standardized tests evaluating intelligence (Reynolds Intellectual Assessment Scales) and language skills (Clinical Evaluation of Language Fundamentals). RESULTS: Total brain gray matter volume did not differ between the breastfed and cow's milk formula groups. However, breastfed children had significantly higher (P < .05, corrected) regional gray matter volume measured by voxel-based morphometry in the left inferior temporal lobe and left superior parietal lobe compared with cow's milk formula-fed children. Breastfed children showed significantly more brain activation in the right frontal and left/right temporal lobes on fMRI when processing the perception task and in the left temporal/occipital lobe when processing the visual language task than cow's milk formula-fed children. The imaging findings were associated with significantly better performance for breastfed than cow's milk formula-fed children on both tasks. CONCLUSIONS: Our findings indicated greater regional gray matter development and better regional gray matter function in breastfed than cow's milk formula-fed children at 8 years of age and suggested that infant diets may have long-term influences on brain development in children.

Infant diet, gender and the development of vagal tone stability during the first two years of life.

Postnatal nutrition influences neurodevelopment, but it is not known whether the development of individual differences in physiologic measures is related to variations in early postnatal diet. To address this issue we studied the stability of vagal tone (V)--an index of individual differences in parasympathetic heart rate control-by measuring resting V quarterly during infancy and again at 2 years in 146 breast-fed (BF), 143 milk formula-fed (MF), and 137 soy formula-fed (SF) infants. Stability of V across infancy was more consistently significant for BF than formula-fed infants. Stability was similar for boys and girls in BF and SF groups but was generally higher in boys than girls in the MF group. Significant stability between infancy and 2 years emerged later in SF than other groups and later in boys than girls. Stability generally peaked between 6 and 9 months-a time when postnatal vagal myelination slows and which may represent a pivotal stage in the development of V stability. These findings indicate that infant diet and gender are important modulators of the early development of autonomic state control.

Smooth pursuit eye movements and attention in psychiatric patients.

The effects of two putative attention-engaging maneuvers on tracking performance were studied in three groups of subjects: inpatients (n = 19), outpatients (n = 19), and controls (n = 20). One method involved realerting subjects during tracking by repeating instructions to track carefully. The second method, a signal detection task incorporated into the tracking stimulus, required that subjects signal their perception of brief interruptions of the tracking light by pressing a hand-held button. The tracking performance of inpatients was significantly inferior to that of both outpatients and controls, whereas tracking performance of these two latter groups did not differ. Verbal realerting did not significantly improve tracking performance in any group; moreover, during the administration of these instructions there was an increase in tracking errors in inpatients. Inpatients also made more tracking errors than comparison groups during signal detection trials. Other subject factors of possible relevance to tracking performance, e.g., age, gender, and level of arousal, were found not to covary with tracking accuracy in a manner which would explain the observed group differences. It is unlikely that voluntary inattention is the basis for the observed impaired tracking in hospitalized psychiatric patients; the data are more consistent with an interpretation based on heightened distractibility or information overload in these patients.