Spontaneous EEG theta/beta ratio and delta-beta coupling in relation to attentional network functioning and self-reported attentional control.

Relationships between electroencephalographic (EEG) slow- and fast-wave frequency bands are considered to be of interest in the study of dispositional affective traits, emotion regulation, and attentional phenomena. However, to date, no previous studies had explored whether both state performance-based and self-reported attentional control (AC) measures potentially relate to different patterns of spontaneous EEG measures, in the absence of emotional stimuli. In the present study, individual differences in spontaneous EEG theta/beta ratio and delta-beta coupling at frontal and parietal sites were explored in a sample of 110 healthy volunteers as potential correlates of individual differences in performance-based attentional network functioning, as measured through the Attentional Network Test for Interactions (ANT-I) and self-reported AC. We found that stronger delta-beta coupling at parietal sites was associated with higher self-reported AC. However, no significant associations were found between executive control network functioning and the EEG ratio or coupling measures. Furthermore, a lower spontaneous fronto-parietal theta/beta ratio was found to be associated with better orienting network functioning. These results are discussed with a focus on the potential utility of spontaneous EEG measures in several cortical regions for capturing trait-like individual differences in temperament-related factors.

Spontaneous EEG activity and spontaneous emotion regulation.

Variability in both frontal and parietal spontaneous EEG activity, using α and ß band power and θ/ß and δ/ß ratios, was explored in a sample of 96 healthy volunteers as a potential correlate of individual differences in spontaneous emotion regulation (SER). Following a baseline EEG recording, participants were asked to continuously rate their discomfort while looking at affective pictures, as well as for a period of time after exposure. Greater spontaneous ß band power in parietal locations, lower frontal and parietal δ/ß ratios, and lower parietal θ/ß ratio were associated with lower ratings of discomfort after the offset of unpleasant pictures. Moreover, lower parietal δ/ß ratio was also related to less time needed to recover from discomfort after exposure to aversive pictures, while only a greater frontal and parietal α band power appeared to be associated with faster recovery from discomfort induced by normative-neutral pictures. However, parietal δ/ß ratio was the only predictor of both minimum discomfort ratings and time needed to downregulate following exposure to unpleasant pictures, and frontal α band power the only spontaneous EEG index that predicted variability in spontaneous down-regulation after the exposure to normative-neutral pictures. Results are discussed focusing on the utility of diverse spontaneous EEG measures in several cortical regions when capturing trait-like individual differences in emotion regulation capabilities and processes.

Attentionally modulated effects of cortisol and mood on memory for emotional faces in healthy young males.

Heightened cortisol levels due to stress or acute administration seem to enhance memory for emotional material, independently of emotional valence. An arousal-driven neurobiological mechanism involving the amygdala has been proposed. The relation between pre-task salivary measures of cortisol (by convention named 'basal levels') and emotionally modulated memory has not been investigated yet. Given the association between higher basal levels of cortisol and indices of low mood, valence-specific effects on emotionally modulated memory could be expected (e.g. mood-congruent or stimulus-specific forms of processing). This study was designed to investigate the relationship between basal levels of salivary cortisol, self-reported mood and spatial memory for neutral, happy and angry facial expressions in healthy young volunteers (N=31). Memory performance was indexed using a modified version of a computerized object-relocation task, using emotional facial expressions as stimuli. Results showed a significant relation between cortisol and depressive mood. More importantly, both the levels of cortisol and depressive mood were inversely related to the memory performance for the happy facial expressions, while a similar relationship between cortisol and memory performance on angry faces neared significance. An explanation in terms of the down-regulation of social behavior by elevated basal cortisol levels is postulated.

Parietal electroencephalogram beta asymmetry and selective attention to angry facial expressions in healthy human subjects.

Research on cerebral affective processing in humans has concentrated on the lateralization of the prefrontal cortex. However, the parietal cortex also seems to play a role in motivation and emotion. In the present study the lateralized role of the parietal cortex in motivated attention was investigated, using an electrophysiological correlate of brain activity (electroencephalogram (EEG)) and a modified Dot probe task, which indexes selective, i.e. avoidant or vigilant attention for angry faces in a spatial display. Twenty-two participants underwent an EEG baseline recording from the F3, F4, P3 and P4 electrode positions, which was followed by the modified Dot probe task. Spectral power in 1 Hz frequency bins were derived for each electrode site and transformed to power density values in the 8-12 Hz (alpha) and 13-30 Hz (beta) frequency range. Log-transformed prefrontal and parietal asymmetries and bias scores for selective attention to angry and happy faces were calculated. Results showed a highly significant relationship between the asymmetry in parietal EEG beta activity and the attentional response to the angry face. Relative more right-sided parietal EEG activity in the beta frequency domain was predictive of a more avoidant response to angry facial expression. This finding suggests that asymmetrical parietal beta activity might be linked to the behavioural dimensions of approach and withdrawal.

A single administration of testosterone induces cardiac accelerative responses to angry faces in healthy young women.

Recently, it was demonstrated how individuals with high levels of testosterone selectively attend toward angry faces. It was argued that this suggests that high levels of testosterone are associated with an aggressive, dominating personality style. In this study, the authors used a double-blind, placebo-controlled design to examine whether exogenous testosterone would induce cardiac acceleration in response to angry faces. Participants (healthy young women) were exposed to neutral, happy, or angry faces. Administration of a single dosage of testosterone (0.5 mg) induced an accelerative cardiac response to angry faces. It is argued that this effect is due to the encouragement of dominance behavior and the inclination toward aggression. Possible mechanisms behind testosterone-driven changes in behavior are discussed with relevance to steroid-responsive networks in the limbic system that drive and control motivational and physiological aspects of social behavior.

Measurement of the false positive rate in a screening program for human immunodeficiency virus infections.

In a program screening civilian applicants for U.S. military service for human immunodeficiency virus (HIV) infection, we studied the frequency of false positive diagnoses retrospectively among applicants seropositive for HIV in a subpopulation with a very low prevalence of infection. That subpopulation was defined as consisting of all applicants tested between October 16, 1985, and June 30, 1987, who were young (17 or 18 years of age) and resided in a rural county in a state with a low incidence of reported acquired immunodeficiency syndrome (n = 135,187). Serum specimens from 15 applicants positive for HIV in this low-prevalence subpopulation were retrieved from a serum bank and retested by two Western blot methods, radioimmunoprecipitation, and an immunoassay constructed from a molecularly cloned and expressed viral envelope polypeptide. Fourteen of the 15 samples were unequivocally positive on all retest assays, and 1 was negative. Thus, the measured rate of false positive diagnoses in this program was 1 in 135,187 persons tested. Factors important in achieving a low false positive rate were redundant, multistep testing algorithm, conservative criteria for interpreting Western blots, the requirement that a second, newly drawn serum specimen be tested for verification before a diagnosis of HIV was considered established, and tight quality control of laboratory testing procedures. We conclude that a screening program for HIV infection in a low-prevalence population can have an acceptably low false positive rate.

Variations in Western blot banding patterns of human T-cell lymphotropic virus type III/lymphadenopathy-associated virus.

Serum samples from 27 patients infected with human T-cell lymphotropic virus type III (14 with acquired immune deficiency syndrome [AIDS] and 13 with AIDS-related complex) were examined for antibodies to viral proteins by the Western blot method and with four different commercial solid-phase enzyme-linked immunosorbent assays (ELISAs). Virus-specific bands on blots at molecular masses of 64, 55, 53, 41, 31, 24, and 17 kilodaltons were observed. Rank correlation matrices were calculated to relate the intensity of viral bands, stage of illness, and ELISA kit optical densities (ODs). Groups of bands tended to covary in intensity: p17, p24, and p55 (gag gene products); p53 and p64 (pol gene products); and p31 (pol/endonuclease gene product) and p41 (env gene product). Blots of sera from AIDS-related complex patients usually showed strong activity against all viral proteins, while those of sera from AIDS patients characteristically showed strong reactivity only at the pol/endonuclease and env bands. For one ELISA kit (Abbott Laboratories, North Chicago, Ill.), ODs correlated well with the env and pol band intensity scores, while ELISA ODs with other kits (from Litton Industries, Sunnyvale, Calif.; Electro-Nucleonics, Inc., Fairfield, N.J.; and E.I. du Pont de Nemours & Co., Inc., Wilmington, Del.) correlated closely with gag band intensity scores. We conclude that human T-cell lymphotropic virus type III Western blot patterns are determined by (i) viral protein processing pathways and (ii) the stage of illness of the patient and may reflect (iii) the ELISA method used for serum screening.

The Amytal interview in the diagnosis of late onset psychosis with cultural features presenting as catatonic stupor.

A case history of a man with atypical psychosis who exhibited catatonic stupor is reported. Amytal interview procedures used and the differential diagnosis for catatonia are discussed. Response to Loxitane was excellent, though this was clouded by the patient's belief in root medicine, a source of cultural incongruity between him and his therapist. Distinguishing between psychosis and cultural belief systems is shown to be essential in therapy.