## 4 Common/Unifying Theoretical-Conceptual Framework
### qEEG Phenotype and Neurophysiological, Cognitive, and Behavioral Traits
#### 4.2.8 Overall Brain Resources (Resilience)  
The overall brain resources reflect the brain's morpho-functional integrity, capacity for self-reorganization, self-regulation, and adaptation, and information processing efficiency. The brain resources domain relates to the general capacity of the brain to withstand neuropathological changes before overt behavioral, functional, or cognitive impairment manifests. This domain unites brain and cognitive reserves [664; 665; 666]. _Brain reserve_ refers to quantitative aspects of the brain (structure or _'hardware'_), including but not limited to the number and size of neurons, the number of connections between neurons, fiber density, axonal diameter, the degree of myelination, the integrity of corticocortical and thalamocortical circuits, hippocampal volume, the number of active synapses in the thalamic nuclei, and the number of potential neural pathways [664; 666; 667; 668; 669]. _Cognitive reserve_ refers to the 'neuropsychological competence' aspects of the brain, that is, how well the underlying 'hardware' is used (functions or '_software_'). It reflects a process where the brain actively attempts to cope with brain challenges or damage by using pre-existing neural networks and/or by recruiting additional or alternative brain regions to support the task network. Cognitive reserve also includes the processes of network efficiency and neural compensation [664; 666; 669; 670].  
In this view, the dualism of brain and cognitive reserves is considered within a single framework--_brain resources_--where the term'resource' refers to the joint structural and functional characteristics of brain networks that offer cognitive protection in disease.  
A person with high overall brain resources has increased compensatory and neuroprotective mechanisms that give the person increased capacity for effective cognitive functioning _in spite of_ neuropathophysiological challenges or aging. A person with high brain resources has a younger brain phenotype and is more likely to remain within normal limits for a longer period of time despite the possible parallel progression of underlying disease [671]. Therefore, a person with high brain resources and a high disease burden may remain asymptomatic due to compensatory and resistant adaptations of the functional brain network [667; 672; 673] (Figure 4).  
A person with low overall brain resources has decreased compensatory and neuroprotective mechanisms that decrease the capacity for effective cognitive functioning even without neuropathophysiological challenges. A person with fewer brain resources has an older brain phenotype, so he or she may express symptoms after a trivial brain dysfunction due to redundant neural pathways and an inflexible or intolerant functional network. Likewise, the brain has a lower threshold for the expression of functional impairments following the onset of brain pathology [667, 672, 673] (Figure 4).  
Since the qEEG oscillatory pattern reflects structural and functional integrity of the brain (see Sections 2.4 and 2.5) and causally relates to neuropsychopathology (see Section 2.15), it is not surprising that overall brain resources are reflected in the characteristics of the qEEG phenotype [8, 112, 113, 116, 119, 121, 122, 136, 143, 185, 187, 671, 675, 676, 678].  
From this brief overview of the fundamental and primary domains of functioning, it is clear that each (a) exhibits trait properties; (b) is expressed along the entire continuum of functioning, from health to pathology; (c) is transdiagnostic; and (d) is reflected in the characteristics of qEEG phenotypes.  
It has been proposed that trait characteristics and qEEG phenotypes should only be evaluated during a resting state [453, 519].