Differential lateralization of trait anxiety and trait fearfulness: Evoked potential correlates

The effect of trait anxiety on the time course of self-relevant processing: Evidence from the perceptual matching task

Studies have widely reported that trait anxiety is associated with a range of cognitive biases toward external negative emotional stimuli. However, few studies have examined whether trait anxiety modulates intrinsic self-relevant processing. This study investigated the electrophysiological mechanism underlying trait anxiety's modulating effect on self-relevant processing. Event-related potentials (ERPs) were recorded while participants performed a perceptual matching task that assigned an arbitrary geometric shape to an association with a "self" or "non-self" label. Results showed larger N1 amplitudes under self-association than under friend-association conditions, and smaller P2 amplitudes for self- than for stranger-association conditions in individuals with high trait anxiety. However, these self-biases in the N1 and P2 stages were not observed in those with low trait anxiety until the later N2 stage, in which the self-association condition provoked smaller N2 amplitudes than the stranger-association condition. In addition, both high and low trait anxiety individuals showed larger P3 amplitudes for the self-association condition than for the friend- and stranger-association conditions. These findings suggest that, although both high and low trait anxiety individuals showed self-bias, high trait anxiety individuals distinguished between self-relevant and non-self-relevant stimuli at an earlier stage, which may reflect hypervigilance to self-relevant stimuli.

Expecting the worst: observations of reactivity to sound in young children with Williams syndrome

The study examined behavioral reactions to sound, including startle eye blinks, in young children with Williams syndrome (WS) using video-based observational techniques. Participants were 21 children with WS and 20 children with other developmental disabilities of mixed etiology between the ages of 2.5 and 6. Groups were matched for chronological age and developmental level. All children participated in a semi-structured play interaction including exposure to mild intensity sounds as emitted from conventional toys. Overall, 90% of the children in the WS group were observed to exhibit overt behavioral reactivity to mild intensity sounds, compared to only 20% in the mixed etiology group. Examination of the temporal sequence indicated that children with WS generally exhibited these behaviors before exposure to sound stimuli, suggesting a relation to anticipatory anxiety. Children with WS also exhibited significantly greater acoustic startle eye blinks, often viewed as an indication of heightened emotional state. Taken together, the current findings confirm the presence of heightened reactivity to sound in WS, behaviors previously investigated using parent report alone. The observed behaviors and their potential relation to anxiety are also discussed.

Is juvenile psychopathy associated with low anxiety and fear in conduct-disordered male offenders?

Although the traditional conceptualization of psychopathy suggests that this construct is negatively associated with anxiety the literature has produced mixed findings. The present study examined the relationship between self-report measures of anxiety/fear and psychopathy assessed using the Psychopathy Checklist: Youth Version in 110 adolescent male offenders with conduct disorder. In line with the literature in children, we found that measures of anxiety and fearfulness exhibited differential associations with different elements of psychopathy. Specifically, we found that trait anxiety was negatively correlated with the affective components of the psychopathy construct and that fearfulness was negatively correlated with the more antisocial components of the construct. The findings are discussed in the context of growing literature on psychopathy assessment in younger cohorts.

Evaluation of PCA and ICA of simulated ERPs: Promax vs. Infomax rotations

Independent components analysis (ICA) and principal components analysis (PCA) are methods used to analyze event-related potential (ERP) and functional imaging (fMRI) data. In the present study, ICA and PCA were directly compared by applying them to simulated ERP datasets. Specifically, PCA was used to generate a subspace of the dataset followed by the application of PCA Promax or ICA Infomax rotations. The simulated datasets were composed of real background EEG activity plus two ERP simulated components. The results suggest that Promax is most effective for temporal analysis, whereas Infomax is most effective for spatial analysis. Failed analyses were examined and used to devise potential diagnostic strategies for both rotations. Finally, the results also showed that decomposition of subject averages yield better results than of grand averages across subjects.

State-dependent regulation of cortical activity by cortisol: An EEG study

In the present study we investigated the effects of cortisol administration on EEG activity in eight healthy volunteers. We administered 35 mg of cortisol in a within-subjects double-blind placebo-controlled design. Cortisol administration caused a global decrease in cortical activity except for an increase frontally at the left, resulting in a significant change in frontal asymmetry. This pattern of results is almost the exact mirror image of one of our previous studies. Comparing subjective activation measures from the present and previous study showed that activation was substantially higher in the present study that was performed in formal testing conditions involving venipuncture, compared to the previous EEG study that was performed in non-formal testing conditions. However, the direction of the present cortisolinduced change in frontal activity asymmetry is consistent with the cortisolinduced change in asymmetric rotation behavior that we recently reported in similar testing conditions. We also found indications that, in contrast to the effects on the EEG measures, effects of cortisol administration on subjective anxiety and plasma oxytocin levels may be sex-dependent. These results are preliminary because of the post-hoc nature and the small number of subjects in the present study. However, they are in line with recent findings by others, suggesting that the effects of cortisol on cortical activity and subjective activation are state dependent and are influenced by testing conditions.

The worried mind: autonomic and prefrontal activation during worrying

To study the psychophysiological correlates of worrying, the authors recorded heart rate, respiratory sinus arrhythmia (RSA), skin conductance level, and alpha electroencephalographic asymmetry in healthy males during baseline, relaxation, worry induction, and anticipation of an impromptu speech task. Compared with baseline, relaxation, and anticipation, worrying was associated with greater heart rate and lower RSA. Worrying was further characterized by higher skin conductance levels compared with baseline but lower levels than during anticipation. Finally, worrying was associated with relatively greater left frontal activity compared with anticipation. Trait public speaking anxiety was positively correlated with left frontal activity during worrying. These results support the notion that worrying is a unique emotional state that is different from fearful anticipation.

Localizing cortical sources of event-related potentials in infants' covert orienting

This study used cortical source analysis to locate potential cortical sources of event-related potentials (ERPs) during covert orienting in infants aged 14 and 20 weeks. The infants were tested in a spatial cueing procedure. The reaction time to localize the target showed response facilitation for valid trials relative to invalid or neutral trials. High-density EEG (126 channels) was recorded during the task, and independent component analysis and equivalent current dipole analysis was used to estimate the cortical sources of the EEG during the task. There was a larger P1 ERP component on the valid trials than the other trials (P1 validity effect). The cortical source analysis suggested that this occurred due to activity in Brodmann's areas 18 and 19. A presaccadic ERP component occurred over the frontal scalp areas (-65 ms) and was larger to a target in a cued location than in uncued locations. A potential cortical source for this ERP component was the superior frontal gyrus on the inferior portion of the prefrontal cortex. Increases from 14 to 20 weeks in amplitude of the P1 validity effect and the presaccadic ERP could be modeled by an increase in activation in the corresponding cortical areas.

Recovering dipole sources from scalp-recorded event-related-potentials using component analysis: principal component analysis and independent component analysis

Principal component analysis (PCA) and independent component analysis (ICA) were examined in their ability to recover dipole sources from simulated data. Datasets of EEG segments were generated that contained cortical sources that were temporally overlapping or non-overlapping, and dipole sources with varying degree of spatial orthogonality. For temporal overlapping sources, both PCA and ICA resulted in components that required multiple-source equivalent current dipole models. The spatially overlapping sources affected the PCA method more than ICA, resulting in single PCA components in which all non-orthogonal sources were represented. For both PCA and ICA, dipole models with fixed-location dipoles successfully accounted for most of the variance in the component weights, even when the spatial or temporal overlap of the generating sources required multiple-dipole models.

Misallocation of variance in event-related potentials: simulation studies on the effects of test power, topography, and baseline-to-peak versus principal component quantifications

Since Wood and McCarthy's simulation study (Electroenceph Clin Neurophysiol 1984;59:249-260), the use of principal component analysis (PCA) as a tool for the identification and quantification of event-related potentials (ERP) has been considered a challenge. Three relevant aspects have not been fully acknowledged in previous studies, however, and were therefore investigated in the present simulation study. Firstly, the impact of test power on the amount of variance misallocation was studied. Secondly, the impact of ERP component topography on variance misallocation was investigated. Thirdly, a systematic evaluation of variance misallocation in baseline-to-peak derived ERP measures was performed. Results based on an overall set of 2700 simulations indicate that: (a) variance misallocation is reduced to an almost acceptable level when an appropriate test power is simulated; (b) the overall amount of variance misallocation remains at an almost acceptable level when systematic topographic effects are simulated in combination with an appropriate test power; and (c) variance misallocation is in fact also a problem in baseline-to-peak measures. These findings confirm that, when used appropriately, PCA is a helpful and efficient tool for the identification and quantification of ERPs.

Callous-unemotional traits and developmental pathways to severe conduct problems

One method for defining pathways through which children develop severe conduct problems is based on the presence or absence of callous-unemotional (CU) traits. This study investigated potential differences between nonreferred children (mean age = 12.36 years; SD = 1.73) with and without CU traits (n = 98). Children with conduct problems, irrespective of the presence of CU traits, tended to have significant problems in emotional and behavioral regulation. In contrast, CU traits, irespective of the presence of conduct problems, were associated with a lack of behavioral inhibition. Hostile attributional biases were associated with conduct problems but only in boys and in the absence of CU traits. These findings suggest that the processes underlying deficits in emotional and behavioral regulation in children with conduct problems may be different for children with CU traits.