John J. B. Allen

Frontal EEG asymmetry as a moderator and mediator of emotion

Frontal EEG asymmetry appears to serve as (1) an individual difference variable related to emotional responding and emotional disorders, and (2) a state-dependent concomitant of emotional responding. Such findings, highlighted in this review, suggest that frontal EEG asymmetry may serve as both a moderator and a mediator of emotion- and motivation-related constructs. Unequivocal evidence supporting frontal EEG asymmetry as a moderator and/or mediator of emotion is lacking, as insufficient attention has been given to analyzing the frontal EEG asymmetries in terms of moderators and mediators. The present report reviews the frontal EEG asymmetry literature from the framework of moderators and mediators, and overviews data analytic strategies that would support claims of moderation and mediation.

Anger and Frontal Brain Activity: EEG Asymmetry Consistent With Approach Motivation Despite Negative Affective Valence

The anterior regions of the left and right cerebral hemispheres have been posited to be specialized for expression and experience of approach and withdrawal processes, respectively. Much of the evidence supporting this hypothesis has been obtained by use of the anterior asymmetry in electroencephalographic alpha activity. In most of this research, however, motivational direction has been confounded with affective valence such that, for instance, approach motivation relates positively with positive affect. In the present research, we tested the hypothesis that dispositional anger, an approach-related motivational tendency with negative valence, would be associated with greater left- than right-anterior activity. Results supported the hypothesis, suggesting that the anterior asymmetry varies as a function of motivational direction rather than affective valence.

Behavioral activation sensitivity and resting frontal EEG asymmetry: Covariation of putative indicators related to risk for mood disorders

Dispositional tendencies toward appetitive motivation have been hypothesized to be related to the development of psychopathology. Moreover, decreased left-frontal cortical activity has been reported in depression and has been related to low-trait positive affect and high-trait negative affect. The present study tested the hypothesis that relatively greater left- than right-frontal cortical activity would be related to heightened approach-related dispositional tendencies. Resting frontal cortical asymmetrical activity, as measured by electroencephalographic activity in the alpha band, was examined in relation to the motivational response tendencies of a behavioral activation system (BAS) and a behavioral inhibition system (BIS), as measured by C. S. Carver and T. L. Whites (1994) BIS-BAS self-report questionnaire. Results supported the hypothesis.

Prelude to and resolution of an error: EEG phase synchrony reveals cognitive control dynamics during action monitoring

Error-related activity in the medial prefrontal cortex (mPFC) is thought to work in conjunction with lateral prefrontal cortex (lPFC) as a part of an action-monitoring network, where errors signal the need for increased cognitive control. The neural mechanism by which this mPFC–lPFC interaction occurs remains unknown. We hypothesized that transient synchronous oscillations in the theta range reflect a mechanism by which these structures interact. To test this hypothesis, we extracted oscillatory phase and power from current–source–density-transformed electroencephalographic data recorded during a Flanker task. Theta power in the mPFC was diminished on the trial preceding an error and increased immediately after an error, consistent with predictions of an action-monitoring system. These power dynamics appeared to take place over a response-related background of oscillatory theta phase coherence. Theta phase synchronization between FCz (mPFC) and F5/6 (lPFC) sites was robustly increased during error trials. The degree of mPFC–lPFC oscillatory synchronization predicted the degree of mPFC power on error trials, and both of these dynamics predicted the degree of posterror reaction time slowing. Oscillatory dynamics in the theta band may in part underlie a mechanism of communication between networks involved in action monitoring and cognitive control.

Frontal EEG asymmetry and the behavioral activation and inhibition systems

Two studies have examined whether there exists a relationship between resting frontal alpha asymmetry and the Behavioral Inhibition and Activation Scales (C. S. Carver & T. L. White, 1994), which are based on Grays Behavioral Inhibition and Behavioral Activation Systems. Findings suggest that greater relative left frontal activity characterizes individuals higher in self-reported behavioral activation sensitivity (E. Harmon-Jones & J. J. B. Allen, 1997; S. K. Sutton & R. J. Davidson, 1997), and, in one instance, lower behavioral inhibition sensitivity (S. K. Sutton & R. J. Davidson, 1997). In the present study, relatively greater left frontal activity correlated positively with behavioral activation scores. No significant relationship between resting frontal alpha asymmetry and the behavioral inhibition score emerged. These data suggest that relatively greater left frontal activity is indeed an index of approach oriented, appetitive motivational tendencies, whereas the relationship between relative right frontal activity and the behavioral inhibition system is likely to be complex and not accounted for by behavioral withdrawal alone.

Issues and assumptions on the road from raw signals to metrics of frontal EEG asymmetry in emotion

There exists a substantial literature examining frontal electroencephalographic asymmetries in emotion, motivation, and psychopathology. Research in this area uses a specialized set of approaches for reducing raw EEG signals to metrics that provide the basis for making inferences about the role of frontal brain activity in emotion. The present review details some of the common data processing routines used in this field of research, with a focus on statistical and methodological issues that have captured, and should capture, the attention of researchers in this field.

Resting frontal electroencephalographic asymmetry in depression: inconsistencies suggest the need to identify mediating factors.

Two studies of the relationship between depression and resting frontal electroencephalographic (EEG) activity are reported. Although considerable research supports the theory of left and right hemispheric specialization for approach and withdrawal behaviors, only four studies involving clinically depressed individuals have been published to date. Despite methodological similarities with published research, no significant differences in frontal activation emerged between depressed and nondepressed participants with either college students having high Beck Depression Inventory scores (Study 1) or with individuals diagnosed with DSM-III-R depression (Study 2). Post hoc analyses in Study 2 revealed one effect confined to lateral frontal leads during the first 2 min of EEG data; this finding was significant in only one of three reference montages. Results are discussed in light of methodological considerations and mediating variables such as temperament and coping styles.

Consensus Statements for Management of Barrett's Dysplasia and Early-Stage Esophageal Adenocarcinoma, Based on a Delphi Process

BACKGROUND & AIMS Esophageal adenocarcinoma (EA) is increasingly common among patients with Barretts esophagus (BE). We aimed to provide consensus recommendations based on the medical literature that clinicians could use to manage patients with BE and low-grade dysplasia, high-grade dysplasia (HGD), or early-stage EA. METHODS We performed an international, multidisciplinary, systematic, evidence-based review of different management strategies for patients with BE and dysplasia or early-stage EA. We used a Delphi process to develop consensus statements. The results of literature searches were screened using a unique, interactive, Web-based data-sifting platform; we used 11,904 papers to inform the choice of statements selected. An a priori threshold of 80% agreement was used to establish consensus for each statement. RESULTS Eighty-one of the 91 statements achieved consensus despite generally low quality of evidence, including 8 clinical statements: (1) specimens from endoscopic resection are better than biopsies for staging lesions, (2) it is important to carefully map the size of the dysplastic areas, (3) patients that receive ablative or surgical therapy require endoscopic follow-up, (4) high-resolution endoscopy is necessary for accurate diagnosis, (5) endoscopic therapy for HGD is preferred to surveillance, (6) endoscopic therapy for HGD is preferred to surgery, (7) the combination of endoscopic resection and radiofrequency ablation is the most effective therapy, and (8) after endoscopic removal of lesions from patients with HGD, all areas of BE should be ablated. CONCLUSIONS We developed a data-sifting platform and used the Delphi process to create evidence-based consensus statements for the management of patients with BE and early-stage EA. This approach identified important clinical features of the diseases and areas for future studies.

Theta lingua franca: A common mid-frontal substrate for action monitoring processes

We present evidence that a multitude of mid-frontal event-related potential (ERP) components partially reflect a common theta band oscillatory process. Specifically, mid-frontal ERP components in the N2 time range and error-related negativity time range are parsimoniously characterized as reflections of theta band activities. Forty participants completed three different tasks with varying stimulus-response demands. Permutation tests were used to identify the dominant time-frequency responses of stimulus- and response-locked conditions as well as the enhanced responses to novelty, conflict, punishment, and error. A dominant theta band feature was found in all conditions, and both ERP component amplitudes and theta power measures were similarly modulated by novelty, conflict, punishment, and error. The findings support the hypothesis that generic and reactive medial prefrontal cortex processes are parsimoniously reflected by theta band activities.

The measurement of foot preference

Foot preference has been given only superficial attention in studies of hemispheric lateralization, although it has potential utility for predicting hemispheric dominance. This paper reports the development of a reliable (alpha = 0.89) 11-item behavioral inventory of foot preference. Since footedness and handedness are only partially related, both must be measured reliably to identify individuals who have a consistent right or left side preference. It has yet to be determined whether footedness or handedness has the stronger relationship to other aspects of cerebral lateralization and whether both measures together predict lateralization better than one of them alone.