A review of alpha activity in integrative brain function: Fundamental physiology, sensory coding, cognition and pathology

Aim of the reviewQuestions related to the genesis and functional correlates of the brain's alpha oscillations around 10 Hz (Alpha) are one of the fundamental research areas in neuroscience. In recent decades, analysis of this activity has been not only the focus of interest for description of sensory‐cognitive processes, but has also led to trials for establishing new hypotheses.The present review and the companion review aim to constitute an ensemble of “reasonings and suggestions” to understand alpha oscillations based on a wide range of accumulated findings rather than a trial to launch a new “alpha theory”.Surveyed descriptions related to physiology and brain functionThe review starts with descriptions of earlier extracellular recordings, field potentials and also considers earlier alpha hypotheses. Analytical descriptions of evoked and event-related responses, event-related desynchronization, the relationship between spontaneous activity and evoked potentials, aging brain, pathology and alpha response in cognitive impairment are in the content of this review. In essence, the gamut of the survey includes a multiplicity of evidence on functional correlates in sensory processing, cognition, memory and vegetative system, including the spinal cord and heart.

► This review includes physiologic fundamentals and theories of alpha activity.
► Alpha activity in evolution, aging and in the vegetative system is discussed.
► Event related desynchronization versus alpha response is described.
► This review opens the way to understand alpha activity in a general frame.