## 4 Common/Unifying Theoretical-Conceptual Framework
### qEEG Phenotype and Neurophysiological, Cognitive, and Behavioral Traits  
Studies on intra- and interindividual differences have revealed that qEEG oscillatory patterns reflect individually specific peculiarities of homeostatic and adaptive regulation [468; 477; 478; 479; 480]. Additionally, it has been demonstrated that the qEEG phenotype reflects the specificity of intracortical and cortico-subcortical interrelations and is, to a significant extent, a neurodynamic substrate of the psychological properties of the personality [481; 482; 483; 484; 485]. Together, these suggest that neurophysiological, cognitive, and behavioral traits are reflected in the characteristics of the qEEG phenotype. Indeed, studies have demonstrated the association between personality traits and qEEG characteristics [486; 487; 488; 489; 500; 501]. Moreover, normal EEG patterns have been correlated with a well-integrated personality (general personality fitness) [502] (for a review, see [503]). Personality traits have been proposed to constitute vulnerability factors for psychopathology, including mental diseases and affective disorders [504; 505; 506; 507; 508; 509; 510; 511], thus suggesting that personality traits and psychopathology are not distinct entities [512]. They both (a) reflect increased vulnerability for and (b) underly any given psychopathology. Thus, it seems that, on one hand, the qEEG phenotypes are related to personality types (see above and also [513]) and psychopathology. On the other hand, personality features are related to psychopathology too. This similarity of qEEG relations between psychopathology and personality traits suggests that they are mediated by the same neurophysiological mechanisms and behavioral patterns. Therefore, it is reasonable to suggest that behaviors intrinsic to personality traits are the same as those that are _exaggerated_ in psychopathological conditions [514]. There are many different individual traits with varying degrees of significance for neurophysiologic regulation, information and emotions processing, and behavior. For the purpose of this article, we will focus on those traits which are (a) expressed along the entire continuum of functioning, from health to pathology; (b) transdiagnostic; and (c) reflected in the characteristics of qEEG phenotypes, thus being fundamental and primary functions that condition (modify, modulate, or mediate) other dimensions. The Research Domain Criteria (RDoC) project, launched by the National Institute of Mental Health in 2009 [515], is the first comprehensive attempt to identify fundamental neurobehavioral dimensions that cut across current heterogeneous disorder categories. According to the RDoC, there are five major domains of functioning:  
* Negative valence domain;
* Positive valence systems;
* Cognitive systems;
* Systems for social processes;
* Arousal/regulatory systems. Since some qEEG characteristics can be related to several domains, constructs, or subconstructs of the RDoC matrix and phenomenally different clinical characteristics are, at a more fundamental level, implementations of one and the same process, we suggest the following fundamental and primary domains of functioning that are (a) expressed along the entire continuum of functioning, from health to pathology; (b) transdiagnostic; and (c) reflected in the characteristics of qEEG phenotypes:  
* Tonic level of vigilance (corresponds to arousal/regulatory systems in RDoC);
* Speed of information processing (corresponds to cognitive systems in RDoC);
* Directedness of the attention (internal vs. external focus) (corresponds to cognitive systems in RDoC);
* Emotional-motivational tendency (corresponds to positive and negative valence systems in RDoC);* Sociability (sensory stimulation and excitement tolerability) (corresponds to systems for social processes in RDoC);
* Anxiety tendency (anxious arousal vs. anxious apprehension) (corresponds to negative valence and arousal/regulatory systems in RDoC);
* Stress regulation (resistance and recovery);
* Overall brain resources (resilience).