Effects of neurofeedback and working memory-combined training on executive functions in healthy young adults.

Given the interest in improving executive functions, the present study examines a promising combination of two training techniques: neurofeedback training (NFT) and working memory training (WMT). NFT targeted increasing the amplitude of individual's upper Alpha frequency band at the parietal midline scalp location (Pz), and WMT consisted of an established computerized protocol with working memory updating and set-shifting components. Healthy participants (n = 140) were randomly allocated to five combinations of training, including visual search training used as an active control training for the WMT; all five groups were compared to a sixth silent control group receiving no training. All groups were evaluated before and after training for resting-state electroencephalogram (EEG) and behavioral executive function measures. The participants in the silent control group were unaware of this procedure, and received one of the training protocols only after study has ended. Results demonstrated significant improvement in the practice tasks in all training groups including non-specific influence of NFT on resting-state EEG spectral topography. There was only a near transfer effect (improvement in working memory task) for WMT, which remained significant in the delayed post-test (after 1 month), in comparison to silent control group but not in comparison to active control training group. The NFT + WMT combined group showed improved mental rotation ability both in the post-training and in the follow-up evaluations. This improvement, however, did not differ significantly from that in the silent control group. We conclude that the current training protocols, including their combination, have very limited influence on the executive functions that were assessed in this study.

A neural correlate for common trait dissociation: Decreased EEG connectivity is related to dissociative absorption.

OBJECTIVE: Dissociation refers to a disintegration between psychological elements; common manifestations are embodied in "absorption and imaginative involvement," a propensity for being immersed in a stimulus while oblivious to the environment, and acting without awareness. Trait dissociation was hypothesized to relate to lower EEG signal connectivity, but studies on healthy populations are scarce. The present study set out to examine whether dissociative absorption in a nonclinical sample would be associated with decreased intrahemispheric coherence. METHOD: In 84 healthy Israeli soldiers (49% females; Mage = 22.24, SD = 2.64), resting-state electroencephalography (rsEEG) was recorded for a period of 3 min with eyes closed and 3 min with eyes open. RESULTS: Decreased coherence was related to high dissociative absorption in the long (frontal-occipital) range, and in one of the pairs of the short range (central-parietal). The effects emerged mostly in the left hemisphere, in both eyes-open and eyes-closed conditions, and for a range of spectral bands, although long-range effects were more pronounced in slow-wave bands (theta and delta). CONCLUSIONS: Dissociative absorption is manifested in segregated cortical activity, supporting the notion that it may represent less integrated mental functioning. The findings contribute to our understanding of the neural correlates of consciousness and personality.

Are resting state spectral power measures related to executive functions in healthy young adults?

Resting-state electroencephalogram (rsEEG) has been found to be associated with psychopathology, intelligence, problem solving, academic performance and is sometimes used as a supportive physiological indicator of enhancement in cognitive training interventions (e.g. neurofeedback, working memory training). In the current study, we measured rsEEG spectral power measures (relative power, between-band ratios and asymmetry) in one hundred sixty five young adults who were also tested on a battery of executive function (EF). We specifically focused on upper Alpha, Theta and Beta frequency bands given their putative role in EF. Our indices enabled finding correlations since they had decent-to-excellent internal and retest reliability and very little range restriction relative to a nation-wide representative large sample. Nonetheless, Bayesian statistical inference indicated support for the null hypothesis concerning lack of monotonic correlation between EF and rsEEG spectral power measures. Therefore, we conclude that, contrary to the quite common interpretation, these rsEEG spectral power measures do not indicate individual differences in the measured EF abilities.