Frontal brain electrical activity in infants of depressed and nondepressed mothers: relation to variations in infant behavior.

In previous studies, infants of depressed mothers have been found to exhibit reduced left frontal brain electrical activity (EEG). The left frontal region has been hypothesized to mediate social approach behaviors and positive affective expression. These findings raise important questions about the cause and nature of atypical EEG patterns in infants of depressed mothers. The present study begins to address some of these questions by examining whether or not variations in patterns of frontal brain activity in infants of depressed and nondepressed mothers are related to variations in infant behavior as observed in naturalistic situations. If such relations exist, are they specific to certain behaviors hypothesized to be mediated by the frontal region (i.e., positive approach behaviors)? Frontal and parietal brain electrical activity was recorded from 14- to 15-month old infants of depressed versus nondepressed mothers during a baseline condition and during conditions designed to elicit interest and positive affect. Infant behavior was observed in naturalistic play conditions, with and without mother, on a separate day from EEG testing. Mothers provided information on infant temperament. Infants of depressed mothers showed less affection and touching of their mothers. For infants of depressed mothers only, reduced left frontal brain activity was found to be related to lower levels of affection toward mother, but not to infant temperament. Furthermore, increased generalized frontal activation was found to be related to higher levels of negative affect, hostility, and tantrums and aggression. Relations between infant brain activity and behavior were not found for parietal EEG activity. These results suggest that infant frontal electrical brain activity is related to variations in infant behavior, especially those involved in positive affiliative behavior and the expression and regulation of negative affect. The nature and cause of atypical patterns of brain activity and question of whether such atypical patterns of frontal brain activity predispose infants to affective disorders in later life are discussed.     

Frontal EEG and emotion regulation: Electrocortical activity in response to emotional film clips is associated with reduced mood induction and attention interference effects

Frontal EEG activity is thought to reflect affective dispositions, but may also reflect the emotional demands of a specific context combined with the capability to regulate emotions in that context. The present study examined this hypothesis by testing whether frontal EEG activity during mood inductions versus a resting baseline predicted emotion regulation. EEG was recorded while participants (N = 66, 40 females) received a fearful, sad, or neutral mood induction. Emotion regulation was measured following the mood inductions as self-reported change in negative mood and as attention interference in a task with mood-congruent emotional distracters. Greater frontal EEG activity during the mood inductions versus baseline was associated with more effective emotion regulation: less post-induction sadness and anxiety and reduced mood-congruent attention interference effects. Effects did not differ between the left and right hemispheres. Results support the hypothesis that frontal EEG activity reflects both emotional context and emotion-regulatory capabilities.     

Sounds elicit relative left frontal alpha activity in 2-month-old infants

As one kind of sounds, human voices are important for language acquisition and human–infant relations. Human voices have positive effects on infants, e.g., soothe infants and evoke an infant's smile. Increased left relative to right frontal alpha activity as assessed by the electroencephalogram (EEG) is considered to reflect approach-related emotions. In the present study, we recorded the EEG in thirty-eight 2-month-old infants during a baseline period while listening to sounds, i.e., human voices. Infants displayed increased relative left frontal alpha activity in response to sounds compared to the baseline condition. These results suggest that sounds can elicit relative left frontal activity in young infants, and that this approach-related emotion presents early in life.     

Sounds elicit relative left frontal alpha activity in 2-month-old infants

As one kind of sounds, human voices are important for language acquisition and human–infant relations. Human voices have positive effects on infants, e.g., soothe infants and evoke an infant's smile. Increased left relative to right frontal alpha activity as assessed by the electroencephalogram (EEG) is considered to reflect approach-related emotions. In the present study, we recorded the EEG in thirty-eight 2-month-old infants during a baseline period while listening to sounds, i.e., human voices. Infants displayed increased relative left frontal alpha activity in response to sounds compared to the baseline condition. These results suggest that sounds can elicit relative left frontal activity in young infants, and that this approach-related emotion presents early in life.     

Neural and behavioral associations of manipulated determination facial expressions

Past research associated relative left frontal cortical activity with positive affect and approach motivation, or the urge to move toward a stimulus. Less work has examined relative left frontal activity and positive emotions ranging from low to high approach motivation, to test whether positive affects that differ in approach motivational intensity influence relative left frontal cortical activity. Participants in the present experiment adopted determination (high approach positive), satisfaction (low approach positive), or neutral facial expressions while electroencephalographic (EEG) activity was recorded. Next, participants completed a task measuring motivational persistence behavior and then they completed self-report emotion questionnaires. Determination compared to satisfaction and neutral facial expressions caused greater relative left frontal activity relative to baseline EEG recordings. Facial expressions did not directly influence task persistence. However, relative left frontal activity correlated positively with persistence on insolvable tasks in the determination condition. These results extend embodiment theories and motivational interpretations of relative left frontal activity.     

Frontal EEG asymmetry and fear reactivity in different contexts at 10 months

Individual differences in observed and maternal-rated fear behaviors and frontal electroencephalogram (EEG) asymmetry were examined in normally developing 10-month-old infants. EEG was recorded during resting baseline, as well as during stranger approach, mask presentation, and toy spider presentation. Mothers completed the Infant Behavior Questionnaire. For mask presentation, baseline and task right frontal EEG asymmetry as well as maternal ratings predicted fear behavior during the mask task. For stranger approach, task-related right frontal EEG asymmetry predicted fear behavior during stranger approach after controlling for baseline asymmetry. There was a trend for task-related right frontal EEG asymmetry to predict fear during presentation of a toy spider after controlling for baseline asymmetry. Maternal report of temperament only added unique variance to the prediction of one fear task after controlling for baseline and task EEG. Assessing fear in multiple situations revealed context-specific individual differences in infant fear.     

First time experiences in infancy: When they appear to be pleasant,Do they activate the adrenocortical stress response?

The effect of a positive first-time experience on adrenocortical activity was examined in 48 6- to 13-month-old infants who took part in two sessions of a YMCA-like mother-infant swim class. Experience was manipulated by comparing Novice swimmers with infants who previously had taken a swim class, and by examining responses to first versus second class session. In addition, the effects of temperamental fear of novelty were examined by maternal report prior to the first session. Preswim and Postswim cortisol levels were compared to measures obtained at the same time of day in two comparison groups, one tested at home and one tested in a playroom at the University. The results yielded no evidence of an adrenocortical stress response (elevated cortisol) to the swim sessions for either the Novice or Experienced swimmers. Infant temperamental fearfulness predicted behavioral but not adrenocortical responses during swimming. Postswim cortisol levels were significantly lower than posttest levels in the two baseline comparison groups, and lower postswim cortisol levels were associated with less negative and more positive emotional behavior and engagement of the swimming experience. These results are consistent with the hypothesis that emotions serve as a major pathway influencing adrenocortical activity, and provide no support for the uncertainty hypothesis of adrenocortical activation.     

Do temperamentally shy children process emotion differently than nonshy children? Behavioral,psychophysiological, and gender differences in reticent preschoolers

We examined regional brain electrical activity (EEG), heart rate, and subjective responses at rest and during the presentation of videoclips designed to elicit a range of emotions (e.g., sadness, anger, happiness, fear) among a sample of healthy 4-year-old children selected for temperamental shyness. We found that shy children exhibited significantly greater relative right central EEG activation at rest and during the presentation of the fear-eliciting videoclip than nonshy children. Shy females displayed greater relative right mid-frontal EEG activation during the sad, happy, and fear videoclips than shy males who displayed greater relative left mid-frontal EEG activation. These results (1) suggest that recent frontal EEG activation/emotion models might be gender-specific and (2) appear to provide the first empirical evidence for recent theoretical notions linking the origins and maintenance of temperamental shyness in children to difficulty in regulating fear responses.     

Approach-related left prefrontal EEG asymmetry predicts muted error-related negativity

In two studies, we used electroencephalography (EEG) to test whether approach-motivation-related brain activity would predict reduced sensitivity to negative outcomes. In both studies, participants (Study 1, N=26; Study 2, N=56) were first recorded for baseline EEG to measure approach-related left frontal EEG activity. They then completed either the color-naming Stroop task (Study 1) or the Multi-Source Interference Task (Study 2) to measure error-related negativity (ERN), an event-related potential that has been associated with aversive motivation and distress. In both studies, higher leftward frontal EEG asymmetry predicted reduced ERN amplitude. Hierarchical regression analyses of the separate frontal nodes that comprised the asymmetry score further showed that left frontal activity predicted reduced ERN amplitude whereas right frontal activity predicted greater ERN amplitude. Results have implications for understanding emotion and motivation and for understanding the personal resilience associated with approach motivated states.     

Frontal EEG and emotion regulation: Electrocortical activity in response to emotional film clips is associated with reduced mood induction and attention interference effects

Frontal EEG activity is thought to reflect affective dispositions, but may also reflect the emotional demands of a specific context combined with the capability to regulate emotions in that context. The present study examined this hypothesis by testing whether frontal EEG activity during mood inductions versus a resting baseline predicted emotion regulation. EEG was recorded while participants (N = 66, 40 females) received a fearful, sad, or neutral mood induction. Emotion regulation was measured following the mood inductions as self-reported change in negative mood and as attention interference in a task with mood-congruent emotional distracters. Greater frontal EEG activity during the mood inductions versus baseline was associated with more effective emotion regulation: less post-induction sadness and anxiety and reduced mood-congruent attention interference effects. Effects did not differ between the left and right hemispheres. Results support the hypothesis that frontal EEG activity reflects both emotional context and emotion-regulatory capabilities.     

Relative right versus left frontal EEG in neonates

Although infants have been noted to have greater relative right or left frontal EEG as early as the neonatal period, other ways in which these newborns differ have not been reported. In this study, 48 newborns were divided on the basis of greater relative right versus greater relative left frontal EEG to determine whether these groups differed in other ways at the neonatal period including behavior, physiology, and biochemistry. We also were interested in whether these EEG patterns were related to any prenatal maternal variables including mood states (depression, anxiety, anger) and biochemistry as well as fetal activity. The greater relative right frontal EEG newborns had mothers with lower prenatal and postnatal serotonin and higher postnatal cortisol levels. The mothers of the greater relative right frontal EEG newborns also had greater relative right frontal EEG activation and lower vagal tone. The greater relative right frontal EEG newborns themselves had elevated cortisol levels, showed a greater number of state changes during sleep/wake behavior observations, and performed less optimally on the Brazelton Neonatal Behavior Assessment (T. B. Brazelton, 1973) including the habituation, motor, range of state, excitability, and depressive symptoms scales. These data suggest that greater relative right frontal EEG newborns may be at greater risk for developmental problems than those with greater relative left frontal EEG activation. In addition, a discriminant function analysis correctly classified 67% of the newborns' EEGs by prenatal maternal variables, suggesting that these might be used to target pregnant women for prenatal intervention.     

Predicting affective responses to exercise using resting EEG frontal asymmetry: Does intensity matter?

Affective responses to exercise may be important for improving adherence to regular programs of exercise. The present study sought to determine whether resting frontal EEG asymmetry, an individual difference measure of affective style, is predictive of affective responses to exercise performed at distinct intensities standardized relative to a metabolic landmark (i.e., the ventilatory threshold, VT). Resting EEG was collected from 30 participants and used to predict affective responses following treadmill running at three exercise intensities: below-VT, at-VT, and above-VT. Affect was assessed [via Activation-Deactivation Adjective Check List, yielding measures of Energetic Arousal (EA) and Tense Arousal (TA)] before, immediately following exercise, after 5 min cool down, and 10 and 20 min post-cool down. Resting mid-frontal asymmetry (F4-F3) significantly predicted EA immediately following below-VT exercise; resting lateral frontal asymmetry (F8-F7) predicted EA at 20 min post-cool down. Resting mid-frontal asymmetry predicted in EA immediately following and following cool down in above-VT exercise. As a whole, frontal asymmetry was predictive of affective responses following exercise, namely greater relative left frontal activity predicting lower EA. This was opposite to the predictions of the valenced motivation model, but may provide some support for the motivation direction model. This is based on the fact that low EA could be indicative of approach motivation, especially at higher exercise intensities.     

Behavioral and neuroendocrine responses in shy children

Previous research has shown that infants who display a high frequency of motor activity and negative affect at 4 months of age are likely to be behaviorally inhibited toddlers. We examined social behaviors, maternal report of temperament, salivary cortisol, and baseline startle responses at age 4 in a sample of children, some of whom displayed a high frequency of motor activity and negative affect at 4 months of age. Infants who displayed this temperamental profile were reported by their mothers as more shy at age 4 compared with other children. We also found that 4-year-olds who displayed a high frequency of wary behavior during peer play exhibited relatively high morning salivary cortisol, were reported as contemporaneously shy by their mothers, and were behaviorally inhibited at 14 months of age. There were no significant relations found between baseline startle and morning salivary cortisol and measures of shyness at age 4. We speculate that high levels of cortisol in shy children may induce changes in the amygdala, exacerbating their fearfulness. © 1997 John Wiley & Sons, Inc. Dev Psychobiol 30: 127–140, 1997     

A capability model of individual differences in frontal EEG asymmetry

Researchers interested in measuring individual differences in affective style via asymmetries in frontal brain activity have depended almost exclusively upon the resting state for EEG recording. This reflects an implicit conceptualization of affective style as a response predisposition that is manifest in frontal EEG asymmetry, with the goal to describe individuals in terms of their general approach or withdrawal tendencies. Alternatively, the response capability conceptualization seeks to identify individual capabilities for approach versus withdrawal responses during emotionally salient events. The capability approach confers a variety of advantages to the study of affective style and personality, and suggests new possibilities for the approach/withdrawal motivational model of frontal EEG asymmetry and emotion. Logical as well as empirical arguments supportive of this conclusion are presented.     

Trait anger predicts relative left frontal cortical activation to anger-inducing stimuli.

Building on past research that has suggested that relatively greater left frontal cortical activity is associated with approach-related anger and that individuals who are high in trait anger are more likely to evidence angry responses, the present research tested whether individuals high in trait anger would be more likely to evidence relatively greater left frontal cortical activity in response to anger-eliciting pictorial stimuli. In the experiment, participants were exposed to pictures intended to evoke anger, fear/disgust, positive, or neutral affective reactions. Electroencephalographic (EEG) activity was recorded continuously, and alpha power was derived from the EEG to measure cortical activity. Trait anger was measured using the Buss and Perry Aggression Questionnaire [Buss, A.H., Perry, M., 1992. The aggression questionnaire. Journal of Personality and Social Psychology, 63, 452-459]. Results revealed that trait anger was positively related to greater relative left frontal cortical activity to anger-evoking pictures but not to other types of pictures.     

EEG in 1-week, 1-month and 3-month-old infants of depressed and non-depressed mothers

EEGs were examined in data collected from 348 1-week, 1-month and 3-month-old infants of depressed and non-depressed mothers across several studies. Both the percentage of infants exhibiting spectral peaks and the frequency in Hz at which those peaks were exhibited increased with age. Consistent with previous studies, infants of depressed mothers exhibited greater left frontal EEG power, suggesting greater relative right frontal EEG activity than infants of non-depressed mothers. This profile was apparent across a narrow frequency range, which shifted from 3-9 Hz at 1 week of age to 4-9 Hz by 3 months of age.     

Frontal electrocortical and cardiovascular reactivity during happiness and anger

The present study investigated electrocortical and cardiovascular reactivity during positive and negative emotion, and examined the relation of asymmetric frontal lobe activation to cardiovascular responses. Participants were 30 healthy, right-handed university students (mean age, 23.9; 60% female; 76% Caucasian). Electroencephalographic (EEG), blood pressure (BP), and heart rate (HR) responses were assessed while subjects engaged in laboratory tasks (personally-relevant recall tasks and film clips) designed to elicit happiness or anger. Happiness-inducing tasks evoked more prominent left than right frontal EEG activation, and greater left frontal EEG activation than anger-inducing tasks. However, anger-inducing tasks were, on average, associated with comparable left and right frontal EEG activation. Irrespective of emotional valence, cardiovascular activation was more pronounced during personally-relevant recall tasks than during the viewing of film clips. During anger recall, both greater left frontal EEG response (r=-0.46, P<0.02) and greater right frontal EEG response (r=-0.45, P<0.02) were correlated significantly with increased HR reactivity during the task. In addition, a right lateralized frontal EEG response during anger-inducing tasks was associated with greater concomitant systolic BP (P<0.03) and diastolic BP (P<0.008) reactivity. Exploratory analyses also indicated that men who displayed a left lateralized frontal EEG response during happiness-inducing tasks showed the greatest concomitant systolic BP and HR reactivity (P's<0.03). These findings suggest that asymmetric frontal EEG responses to emotional arousal may elicit different patterns of cardiovascular reactivity in healthy adults.     

Individual differences in object permanence performance at 8 months: Locomotor experience and brain electrical activity

This work was designed to investigate individual differences in hands-and-knees crawling and frontal brain electrical activity with respect to object permanence performance in 76 eight-month-old infants. Four groups of infants (one prelocomotor and 3 with varying lengths of hands-and-knees crawling experience) were tested on an object permanence scale in a research design similar to that used by Kermoian and Campos (1988). In addition, baseline EEG was recorded and used as an indicator of brain development, as in the Bell and Fox (1992) longitudinal study. Individual differences in frontal and occipital EEG power and in locomotor experience were associated with performance on the object permanence task. Infants successful at A-not-B exhibited greater frontal EEG power and greater occipital EEG power than unsuccessful infants. In contrast to Kermoian and Campos (1988), who noted that long-term crawling experience was associated with higher performance on an object permanence scale, infants in this study with any amount of hands and knees crawling experience performed at a higher level on the object permanence scale than prelocomotor infants. There was no interaction among brain electrical activity, locomotor experience, and object permanence performance. These data highlight the value of electrophysiological research and the need for a brain-behavior model of object permanence performance that incorporates both electrophysiological and behavioral factors. © 1997 John Wiley & Sons, Inc. Dev Psychobiol 31: 287–297, 1997     

Low positive emotionality in young children: association with EEG asymmetry

Low positive emotionality (PE; e.g., listlessness, anhedonia, and lack of enthusiasm) has been hypothesized to be a temperamental precursor or risk factor for depression. The present study sought to evaluate the validity of this hypothesis by testing whether low PE children have similar external correlates as individuals with depression. This paper focused on the external correlate of EEG asymmetry. Previous studies have reported that individuals at risk for depression exhibited a frontal EEG asymmetry (greater right than left activity). Others have reported an association with posterior asymmetries (greater left than right activity). In the present study, children classified as having low PE at age 3 exhibited an overall asymmetry at age 5-6 with less relative activity in the right hemisphere. This asymmetry appeared to be largely due to a difference in the posterior region because children with low PE exhibited decreased right posterior activity whereas high PE children exhibited no posterior asymmetry. These findings support the construct validity of the hypothesis that low PE may be a temperamental precursor or risk factor for depression.     

Anterior electroencephalographic asymmetry changes in elderly women in response to a pleasant and an unpleasant odor

Greater left than right frontal EEG activation has been associated with increased positive and/or decreased negative affect, whereas greater right than left frontal activation has been associated with the opposite pattern. Substantial research has documented the trait properties of asymmetry, as well as responses to pleasant and unpleasant stimuli. The present study examined changes in anterior alpha asymmetries in response to pleasant (vanilla), unpleasant (valerian), and neutral (water) odors. As predicted, vanilla produced relative left frontal activation compared to valerian and water. Frontal asymmetry did not differ in response to valerian compared to water. The results are consistent with the hypothesis that the left frontal region of the brain is involved in positive/approach-related emotion, and extend previous results into the olfactory realm.