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Biomedical subjects

Nathan A Fox

Publications and source records attributed to Nathan A Fox.

At least 19 recordsLinked to original sources
PubMed2006

Behavioral and electrophysiological markers of selective attention in children of parents with a history of depression.

BACKGROUND: Individual differences in selective attention may play a role in moderating psychological vulnerabilities by shaping the ability to self-regulate emotion. Children of parents with childhood-onset depression (COD) are at increased risk for socioemotional difficulties. This study examined potential differences in selective attention as a function of parental COD. METHODS: Children (n = 33, ages 6 to 10) participated in a Posner cued attention task under neutral and affective conditions. Behavioral (reaction time [RT]; errors) and event-related potential (ERP) data were collected during the task. RESULTS: Performance in the Posner task under the affective condition was marked by significant decreases in RTs, an increase in errors, and an increased validity effect (difference in RTs to the cued vs. uncued trials) relative to performance under neutral conditions. Children of parents with COD were slower in their response rates compared with control children. The at-risk children also showed larger P3 and slow wave amplitudes in anterior scalp sites, particularly during the affective Posner task. CONCLUSIONS: These data suggest that there are subtle deficits in selective attention among the offspring of individuals with COD, requiring that they engage more processing resources to perform effectively. This may affect their ability to adequately regulate emotion under stress.

Adult↗
PubMed2006

Striatal functional alteration in adolescents characterized by early childhood behavioral inhibition.

The temperamental style of behavioral inhibition has been characterized by exaggerated behavioral and neural responses to cues signaling threat. Virtually no work, however, has addressed whether behavioral inhibition may also confer heightened brain activation in response to positively valenced incentives. We used event-related functional MRI (fMRI) and a monetary incentive delay task to examine whether the neural response to incentives is also greater in adolescents characterized as behaviorally inhibited early in life compared with those characterized as non-inhibited. Whereas task performance did not differ between groups, fMRI revealed greater striatal activation to incentives in behaviorally inhibited adolescents than in non-inhibited adolescents. This was regardless of whether the incentive was an anticipated gain or loss. Alteration in neural systems underlying behavior modulated by both negative and positive contingencies may represent a correlate of behavioral inhibition that also underlies vulnerability to various forms of developmental psychopathology.

Adolescent↗
PubMed2006

Contextual basis of maternal perceptions of infant temperament.

To elucidate the differential saliency of infant emotions to mothers across interactive contexts, the authors examined the moderating role of observed infant affect during interactions with mother in the relation between maternal and laboratory-based ratings of infant temperament. Fifty-nine developmentally healthy 9-month-old infants were judged for degree of infant positive, infant negative, and mother-infant mutually positive affect during the course of object-focused and routine home-based activities with mother. Mothers completed the Infant Behavior Questionnaire (M. K. Rothbart, 1981), and infants underwent the Laboratory Temperament Assessment Battery (H. H. Goldsmith & M. K. Rothbart, 1999). Results revealed that maternal and observer ratings of infant negativity converged when infants manifested high degrees of negative affect during routine home-based activities. Maternal and observer ratings of infant positivity converged when infants experienced low mutually positive affect during play. These findings support the hypothesis that maternal perceptions are based on mothers' experiences with their infants but that the salience of infant temperamental characteristics to mothers varies across emotion and interactive context.

Female↗
PubMed2006

Ordinary variations in maternal caregiving influence human infants' stress reactivity.

We sought to extend earlier work by examining whether there are ordinary variations in human maternal caregiving behavior (MCB) that are related to stress reactivity in infants. We observed 185 mother-infant dyads and used standard coding systems to identify variations in caregiving behavior. We then created two extreme groups and found that infants receiving low-quality MCB showed more fearfulness, less positive joint attention, and greater right frontal electroencephalographic asymmetry than infants receiving high-quality MCB. Group differences in stress reactivity were not a result of measured infant temperament. However, infants receiving low-quality MCB manifested significantly more negative affect during caregiving activities than did infants receiving high-quality MCB. The results suggest that ordinary variations in MCB may influence the expression of neural systems involved in stress reactivity in human infants.

Caregivers↗
PubMed2006

Maternal depression, child frontal asymmetry, and child affective behavior as factors in child behavior problems.

BACKGROUND: Despite findings that parent depression increases children's risk for internalizing and externalizing problems, little is known about other factors that combine with parent depression to contribute to behavior problems. METHODS: As part of a longitudinal, interdisciplinary study on childhood-onset depression (COD), we examined the association of mother history of COD, child frontal electroencephalogram asymmetry, and affective behavior with children's concurrent behavior problems. RESULTS: Children in the COD group had higher anxious/depressed and aggressive problems than did children in the control group, but this was qualified by a COD-by-asymmetry interaction effect. For COD but not control children, left frontal asymmetry was associated with both anxious/depressed and aggressive child problems. Children with left frontal asymmetry and low affect regulation behavior had higher anxious/depressed problems than did those with high affect regulation behavior. Boys with left frontal asymmetry had higher aggressive problems than did those with right frontal asymmetry. CONCLUSIONS: In children of mothers with COD, physiological and behavioral indices of affect regulation may constitute risks for behavior problems.

Adult↗
PubMed2005

Auditory-visual fusion in speech perception in children with cochlear implants.

Speech, for most of us, is a bimodal percept whenever we both hear the voice and see the lip movements of a speaker. Children who are born deaf never have this bimodal experience. We tested children who had been deaf from birth and who subsequently received cochlear implants for their ability to fuse the auditory information provided by their implants with visual information about lip movements for speech perception. For most of the children with implants (92%), perception was dominated by vision when visual and auditory speech information conflicted. For some, bimodal fusion was strong and consistent, demonstrating a remarkable plasticity in their ability to form auditory-visual associations despite the atypical stimulation provided by implants. The likelihood of consistent auditory-visual fusion declined with age at implant beyond 2.5 years, suggesting a sensitive period for bimodal integration in speech perception.

Adult↗
PubMed2005

Children's affect regulation during a disappointment: psychophysiological responses and relation to parent history of depression.

Psychophysiological responses during affect regulation were examined in 57 children ages 3-9 years, 41 of whom had a parent history of childhood-onset depression (COD). During a structured laboratory task, children were given first a disappointing toy and then a desired toy. Frontal electroencephalogram (EEG) asymmetry, respiratory sinus arrhythmia (RSA), heart period, and heart period variability were measured during resting and task conditions. Affective and self-regulatory behaviors were coded from videotape. In 3-5-year olds, greater relative right frontal activity was associated with withdrawal behavior. High heart period was associated with approach behavior. Compared with children of psychiatrically healthy parents, children of parents with COD exhibited poor heart period recovery after disappointment. For children of parents with COD, greater relative left frontal activity was related to concurrent internalizing and externalizing problems, and low resting RSA was related to internalizing problems. Physiological responses associated with affect regulation may help identify children at risk for depression.

Affect↗
PubMed2005

Long-term stability of frontal electroencephalographic asymmetry in adults with a history of depression and controls.

We investigated the stability in resting EEG across a 1- to 3-year interval in 49 adults (33 female and 16 male) with a history of unipolar depression (first onset prior to the age of 14) and 50 controls (33 female and 17 male) with no history of major psychopathology. Current depressive symptoms were quantified by self-report at both assessments. For the entire sample, EEG asymmetry in the alpha range was moderately stable (intraclass correlations between 0.39 and 0.61). Sex, history of depression, depressive symptom severity at Time 2, and change in symptom severity between Time 1 and Time 2 were unrelated to stability of EEG asymmetry. These findings support the view that resting frontal EEG asymmetry reflects a moderately stable individual difference in adults, irrespective of sex and history of depression.

Adult↗
PubMed2005

The impact of reward, punishment, and frustration on attention in pediatric bipolar disorder.

BACKGROUND: Theories in affective neuroscience suggest that mood disorders involve perturbations in attention-emotion interactions. We tested the hypothesis that frustration adversely impacts attention and behavior in children with bipolar disorder (BPD). METHODS: Thirty-five children with BPD and 26 normal control subjects completed: 1) a Posner attention task with feedback but no contingencies; 2) an affective Posner with contingencies; and 3) an affective Posner that used rigged feedback to induce frustration. Reaction time (RT) and event-related potential (ERP) data were collected. RESULTS: At baseline (task 1), there were no between-group differences in behavior or ERPs. Children with BPD exhibited reduced parietal P3 amplitude on task 3 only. On trials occurring after negative feedback, control subjects showed decreased RT when contingencies were introduced (task 2), whereas BPD subjects did not. CONCLUSIONS: The introduction of contingencies was associated with impaired performance of children with BPD, suggesting deficits in their ability to adapt to changing contingencies. In addition, frustration was associated with disrupted attention allocation in children with BPD. We hypothesize that children with BPD inappropriately deployed attention to their internal frustration rather than to the task, causing impaired performance.

Adolescent↗
PubMed2005

Affect-modulated startle in adults with childhood-onset depression: relations to bipolar course and number of lifetime depressive episodes.

To study affect regulation in adults with unipolar (n=38) and bipolar (n=38) forms of childhood-onset depression (COD), as compared with adults with no history of psychiatric illness (n=60), we examined affective modulation of the startle eyeblink reflex. Participants were subjected to binaural bursts of white noise while viewing pictures designed to elicit pleasant, neutral, or unpleasant affective states. The blink response was recorded from surface electrodes over the orbicularis oculi muscle during and following pictures. Participants rated the valence and arousal of their responses. Unlike control or bipolar groups, the unipolar group displayed a greater startle during the neutral condition than during the pleasant condition, and failed to display an increase in startle during the unpleasant condition. The bipolar group, unlike the unipolar and control groups, displayed a similar startle response after pleasant and unpleasant pictures. Participants with a high number of lifetime depressive episodes displayed a blunted startle response across affective conditions. Groups reported similar subjective responses to affective stimuli. Current affective symptoms and comorbid diagnoses did not influence startle modulation. In unipolar and bipolar forms of COD, unusual affective modulation or maintenance of the startle response, respectively, may reflect underlying deficits in affect regulation.

Acoustic Stimulation↗
PubMed2005

Temperament and anxiety disorders.

Recently, multidisciplinary research teams have come together to assess the emergence, course, and treatment of anxiety disorders in young children and adolescents. A number of researchers have suggested that early temperament traits may play a significant role in the causes and maintenance of early anxiety. This article reviews the current understanding of temperament and anxiety as separate constructs and then attempts to examine the developmental links between the two constructs. The authors examine the outstanding issues that must be addressed before the benefits of bridging these traditionally independent fields of study can be fully exploited.

Adaptation, Psychological↗
PubMed2005

Evidence for a gene-environment interaction in predicting behavioral inhibition in middle childhood.

Gene-environment interactions are presumed to shape human behavior during early development. However, no human research has demonstrated that such interactions lead to stable individual differences in fear responses. We tested this possibility by focusing on a polymorphism in the promoter region of the gene for the serotonin transporter (5-HTT). This polymorphism has been linked to many indices of serotonin activity. Specifically, we tested the hypothesis that an interaction between children's 5-HTT status and maternal reports of social support predicts inhibited behavior with unfamiliar peers in middle childhood. Results were consistent with this hypothesis: Children with the combination of the short 5-HTT allele and low social support had increased risk for behavioral inhibition in middle childhood.

Child↗
PubMed2005

Behavioral inhibition: linking biology and behavior within a developmental framework.

Behavioral inhibition refers to a temperament or style of reacting that some infants and young children exhibit when confronted with novel situations or unfamiliar adults or peers. Research on behavioral inhibition has examined the link between this set of behaviors to the neural systems involved in the experience and expression of fear. There are strong parallels between the physiology of behaviorally inhibited children and the activation of physiological systems associated with conditioned and unconditioned fear. Research has examined which caregiving behaviors support the frequency of behavioral inhibition across development, and work on the interface of cognitive processes and behavioral inhibition reveal both how certain cognitive processes moderate behavioral inhibition and how this temperament affects the development of cognition. This research has taken place within a context of the possibility that stable behavioral inhibition may be a risk factor for psychopathology, particularly anxiety disorders in older children. The current chapter reviews these areas of research and provides an integrative account of the broad impact of behavioral inhibition research.

Affect↗
PubMed2004

Children's narratives and patterns of cardiac reactivity.

The present study examines the associations between narrative processing, narrative production, and cardiac rate and variability in children. Heart period (HP) and vagal tone (VT) were computed for fifty-eight 7-year-olds (29 males) during a resting baseline and during epochs in which the children listened to and completed a selected set of story-stems from the MacArthur Story-Stem Battery (I. Bretherton, D. Oppenheim, H. Buchsbaum, R. N. Emde, & the MacArthur Narrative Group, 1990). Significant decreases in HP and VT were observed between a resting baseline and epochs of story-stem presentation by the experimenter. In addition, HP was shorter and VT lower during children's narrative production to emotionally laden story-stems compared with narration to a neutral story-stem. Furthermore, narrative and cardiac responses to stories containing separation-reunion themes reflected increased emotional and cognitive load compared with responses to stories that did not contain such themes. Finally, children who showed VT suppression in response to emotion-laden stories produced more coherent and adaptive narratives compared to those of children who did not show VT suppression. The findings suggest interplay between the cognitive-emotional processes associated with narrative processing and production and cardiac activation patterns.

Affect↗
PubMed2004

The development of P50 suppression in the auditory event-related potential.

The development of P50 suppression in the auditory event-related potential was examined in 32 participants aged 7-13 years and the relation of P50 suppression to individual differences in social withdrawal was investigated. Auditory click pairs were presented binaurally and the amplitude of the P50 component was measured for the two clicks. Across the whole sample, P50 amplitude to the second click was significantly smaller than P50 amplitude to the first click, although around one third of participants showed augmentation of the P50 to the second click. For the children who showed P50 suppression, the magnitude of P50 suppression increased with age and reached adult levels in the oldest participants. P50 suppression did not vary with the extent of social withdrawal behaviors.

Acoustic Stimulation↗
PubMed2004

Automatic correction of ocular artifacts in the EEG: a comparison of regression-based and component-based methods.

A variety of procedures have been proposed to correct ocular artifacts in the electroencephalogram (EEG), including methods based on regression, principal components analysis (PCA) and independent component analysis (ICA). The current study compared these three methods, and it evaluated a modified regression approach using Bayesian adaptive regression splines to filter the electrooculogram (EOG) before computing correction factors. We applied each artifact correction procedure to real and simulated EEG data of varying epoch lengths and then quantified the impact of correction on spectral parameters of the EEG. We found that the adaptive filter improved regression-based artifact correction. An automated PCA method effectively reduced ocular artifacts and resulted in minimal spectral distortion, whereas ICA correction appeared to distort power between 5 and 20 Hz. In general, reducing the epoch length improved the accuracy of estimating spectral power in the alpha (7.5-12.5 Hz) and beta (12.5-19.5 Hz) bands, but it worsened the accuracy for power in the theta (3.5-7.5 Hz) band and distorted time domain features. Results supported the use of regression-based and PCA-based ocular artifact correction and suggested a need for further studies examining possible spectral distortion from ICA-based correction procedures.

Adult↗
PubMed2004

A comparison of the electroencephalogram between institutionalized and community children in Romania.

Electroencephalographic (EEG) data were collected from a sample of institutionalized infants and young children in Bucharest, Romania, and were compared with EEG data from age-matched children from the local community who had never been institutionalized and who were living with their families in the Bucharest area. Compared with the never-institutionalized group, the institutionalized group showed a pattern of increased low-frequency (theta) power in posterior scalp regions and decreased high-frequency (alpha and beta) power, particularly at frontal and temporal electrode sites. This finding is consistent with EEG studies of children facing environmental adversity and children with learning disorders. The institutionalized group also showed less marked hemispheric EEG asymmetries than the never-institutionalized group, particularly in the temporal region. The results are discussed in the context of two models: that the pattern of EEG in the institutionalized children reflects a maturational lag in nervous system development, or that it reflects tonic cortical hypoactivation.

Alpha Rhythm↗