The term “brain (or neural) oscillations” refers to the rhythmic and/or repetitive electrical activity generated spontaneously and in response to stimuli by neural tissue in the central nervous system, the discovery of which is generally credited to Hans Berger (1873-1941), the recorder of the first electroencephalogram. The role of brain oscillations as functional building blocks in sensory-cognitive processes has gained tremendous importance in recent decades. Event-related oscillations (ERO) in the alpha, beta, gamma, delta, and theta frequency windows are highly modified throughout the cortex in pathologic brains, in particular from patients with cognitive impairment. However, they can only be characterized as clinical biomarkers by using a wide range of strategies and mathematical parameters. The oscillatory changes in multiple frequency windows and whole cortex should be taken Into consideration by analyzing relevant changes in the amplitude of function-related oscillations, together with multiple connectivity deficits. The aims of this article are threefold:
