Michelle K. Jetha

Electrophysiological Changes during Adolescence: A Review.

While psychological research has long shown that adolescence is a period of major cognitive and affective transition, recent neurophysiological research has shown that adolescence is also accompanied by observable maturational changes in the brain, both in terms of structure and neurotransmitter function. Given this situation, we would expect that there should be observable and perhaps major changes in electrocortical activity and responses. In this review, we discuss developmental reductions in EEG power and alterations in the dominant band of EEG oscillation frequency, moderated by developmental factors such as growth-related changes in grey and white matter, and in the developmental history of cognitive and sociocultural stressors. Similarly, we summarize alterations in event-related potential components reflecting stimulus processing, response monitoring, and response anticipation. We review the literature on such changes in EEG and event-related potentials during the adolescent period and summarize some of the new developments in the field as well as interpretative difficulties.

Regional EEG alpha power, coherence, and behavioral symptomatology in autism spectrum disorder

OBJECTIVE Although distinct patterns of resting brain electrical activity (EEG) and functional connectivity are believed to distinguish individuals with autism spectrum disorders (ASD) from their unimpaired peers, researchers have only recently begun to link patterns of brain activity and connectivity to behavior in ASD. METHOD We examined regional eyes-closed and eyes-open EEG alpha power and coherence at rest in relation to self-reported perceptual and social behavior in 15 adults diagnosed with ASD and a matched comparison group of 16 unimpaired adults. RESULTS The groups did not differ on eyes-closed EEG alpha power or coherence, but adults with ASD showed less alpha suppression for the eyes-open condition than did controls. In the ASD group, preferential attention to detail (perceptual domain) was associated with lower levels of alpha activity and reduced coherence in posterior regions. No relations between social interaction difficulties (social domain) and alpha measures were found for either group alone. CONCLUSIONS These relations suggest that the processing of perceptual details may be carried out by relatively less synchronized neuronal units in adults with ASD, and may be relatively automatic. SIGNIFICANCE Findings are discussed in relation to recent models of narrow minicolumnar brain structure and reduced functional neural connectivity in ASD.

Autonomic predictors of Stroop performance in young and middle-aged adults.

Although changes in autonomic activity have been extensively examined as responses to cognitive challenges, relatively few studies have used individual differences in autonomic parameters to predict executive performance in healthy adults. Here we examined baseline and task-related changes in heart rate and heart rate variability (measured by respiratory sinus arrhythmia (RSA)) to predict performance of a pictorial Stroop task in a group of 81 healthy adults aged 17-55. Greater autonomic reactivity (increased heart rate and reduced RSA for task performance) was associated with faster colour naming of faces in the Stroop task. Dividing the group by median age revealed that middle-aged adults reduced RSA to a greater degree than their younger counterparts in the context of equivalent performance across groups. Findings suggest that performance of executive function tasks that evoke attentional control may depend in part on the responsiveness of autonomic control parameters via age-dependent mechanisms.

Non-invasive repeated measurement of urinary progesterone, 17β-estradiol, and testosterone in developing, cycling, pregnant, and postpartum female mice

Excretory samples from adult female mice were collected non-invasively during development, estrous cycling, pregnancy, and postpartum. In initial studies, urinary measures were statistically more dynamic over days than were fecal measures; thus subsequent studies focused on urine. Higher 17beta-estradiol levels were present in isolated females than in those exposed to males. In cycling females, urinary 17beta-estradiol was more variable than were measures of testosterone or progesterone, showing peaks with an approximate 5-day periodicity. When urinary estradiol and progesterone were monitored in conjunction with vaginal smear cell counts, patterns were idiosyncratic; most females showed distinct peaks in urinary steroids, not in clear synchrony with vaginal cell cornification. Levels of progesterone rose markedly during the first 10 days of pregnancy, then declined before birth. Estradiol showed a substantial peak on days 7-8 of gestation in all females measured. Urinary testosterone was not dynamic during pregnancy, but rose in immediate prenatal and postpartum measures. During post-weaning, pre-pubertal development, urinary levels of progesterone remained constant but levels of estradiol rose substantially over time.

The role of resting frontal EEG asymmetry in psychopathology: Afferent or efferent filter?

Resting EEG asymmetry evident early in life is thought to bias affective behaviors and contribute to the development of psychopathology. However, it remains unclear at what stage of information processing this bias occurs. Asymmetry may serve as an afferent filter, modulating emotional reactivity to incoming stimuli; or as an efferent filter, modulating behavioral response tendencies under emotional conditions. This study examines 209 kindergarten children (M = 6.03 years old) to test predictions put forth by the two models. Resting asymmetry was examined in conjunction with electrodermal and cardiac measures of physiological reactivity to four emotion-inducing film clips (fear, sad, happy, anger) and teacher ratings of psychopathology. Results confirm an association between increased right side cortical activation and internalizing symptom severity as well as left activation and externalizing symptom severity. Significant interactions between resting asymmetry and physiological reactivity to emotion indicate that physiological reactivity moderates the association between resting asymmetry and symptoms of psychopathology.

Shyness and the first 100 ms of emotional face processing

Although shyness is presumed to be related to an increased sensitivity to detect motivationally salient social stimuli, we know little of how shyness affects the early perception of facial emotions. We demonstrate here that individual differences in normative shyness were related to brain responses to some emotional faces as early as the P1 electrocortical component, 80–130 ms after stimulus onset. High-shy individuals showed reduced P1 amplitude for fearful faces compared to neutral faces. Low-shy individuals processed happy faces faster than other emotions and showed increased P1 amplitudes for happy faces over neutral faces. Regardless of shyness level, participants showed increased amplitudes in the N170 component (130–200 ms) for all emotions over neutral conditions, particularly for the emotion of fear. This study presents the first evidence that shyness is related to early electrocortical responses to the processing of fearful faces, consistent with a fast-path amygdala sensitivity model.

An event-related source localization study of response monitoring and social impairments in autism spectrum disorder.

A number of studies suggest anterior cingulate cortex (ACC) abnormalities in autism spectrum disorder (ASD), which might underlie response monitoring and social impairments exhibited by children and adolescents with ASD. The goal of the present study was to extend this work by examining error and correct response monitoring using event-related potentials (ERN, Pe, CRN) and LORETA source localization in high functioning adults with ASD and controls. Adults with ASD showed reduced ERN and Pe amplitudes and reduced rostral ACC activation compared with controls. Adults with ASD also showed less differentiation between error and correct ERP components. Social impairments and higher overall autism symptoms were related to reduced rostral ACC activity at the time of the ERN, particularly in adults with ASD. These findings suggest that reduced ACC activity may reflect a putative brain mechanism involved in the origins and maintenance of social impairments and raise the possibility of the presence of stable brain-behavior relation impairment across development in some individuals with ASD.

Temperament and its relation to social functioning in schizophrenia

Background: We previously noted increased shyness in stable community outpatients with schizophrenia compared to healthy controls and that shyness may be a risk factor for social functioning impairment in this population (Goldberg & Schmidt, 2001). Aims: We attempted to replicate and extend these findings by comparing the use of a brief trait measure of shyness and sociability (SS; Cheek, 1983; Cheek & Buss, 1981) with the longer Temperament and Character Inventory (TCI; Cloninger, Przybeck, Svrakic, & Wetzel, 1994) used traditionally in work to measure personality dimensions in this population. Methods: A group of stable outpatients with schizophrenia (n = 41) and healthy controls (n = 41) matched on age and gender were compared on the SS and TCI measures. Patients were assessed on clinical symptoms using the Positive and Negative Symptom Scale (PANSS) and on social functioning measures using a Quality of Life Scale (QLS). Results: Patients reported significantly higher shyness, retrospective inhibition and harm avoidance, and lower novelty seeking, self-directedness and cooperativeness than healthy adults, replicating previous findings. Shyness and sociability were related to conceptually linked dimensional sub-scales of the TCI and were predictive of social functioning in the patient group. Importantly, scores on these measures were unrelated to symptom profiles and explained additional variance in social functioning beyond clinical symptoms. Conclusions: These findings suggest that individual differences in trait shyness and sociability may influence social functioning in stable outpatients with schizophrenia. The results also support the use of the brief trait measures of shyness and sociability in this population.

Behavioral and cardiac responses to emotional stroop in adults with autism spectrum disorders: influence of medication

Researchers have recently hypothesized that autism spectrum disorders (ASD) may be partly characterized by physiological over‐arousal. One way to assess physiological arousal is through autonomic measures. Here heart period (HP) and parasympathetic activity measured by respiratory sinus arrhythmia (RSA) were examined in adults with ASD and matched controls at rest and during performance of an emotional Stroop task. Resting HP and RSA were lower in adults with ASD than in matched controls, consistent with hypothesized over‐arousal in ASD. However, dividing the ASD group on the basis of antipsychotic medication usage revealed that group differences in autonomic arousal may be related to the effects of these medications or their correlates. Autonomic adjustments for Stroop performance were comparable across groups, but in the control group, larger RSA reductions were correlated with faster responding (i.e., better performance). This relation was reversed in the unmedicated ASD group and absent in the medicated ASD group. Findings highlight the importance of considering medication status in the recently burgeoning area of psychophysiological studies of autism. Autism Res 2011, 4: 98–108.

Shyness and emotional face processing in schizophrenia: an ERP study.

Shyness in healthy controls has been related to early event-related potential (ERP) responses to emotional faces. Patients with schizophrenia typically demonstrate increased shyness that is stable and related to reduced social functioning. We indexed early ERP responses to emotional faces in relation to shyness in 40 outpatients with schizophrenia and 39 healthy controls. Patients with low-to-medium shyness showed reductions in P100 amplitude to emotional compared to neutral faces as shyness increased. Patients reporting medium-to-high shyness demonstrated the opposite pattern; P100 amplitude sharply increased as shyness increased, possibly reflecting heightened vigilance. When a restricted range of shyness scores was used to equalize scores between groups, patients showed increased N170 amplitude to emotional faces as shyness increased, whereas controls demonstrated the opposite pattern. The implications of the findings are discussed with respect to informing vulnerability to social functioning impairment and psychosocial stress in this population.