Invited Review
A short review of alpha activity in cognitive processes and in cognitive impairment

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Abstract

Aim of the report

In the companion report (Başar, this volume), the physiological fundaments of alpha activity in integrative brain function are described. The present report is a review of the significant role of alpha activity in memory and cognitive processes in healthy subjects, and in cognitive impairment. The role of neurotransmitters is also described, briefly, in this context.

Towards an understanding of brain alpha

Despite numerous experimental studies, it is indicated that the presented results are only appropriate to establish an ensemble of reasonings and suggestions for analyzing “alphas” in the whole brain. In turn, in the near future, these reasonings and suggestions may serve (or are indispensable to serve) as fundaments of more general and tenable hypotheses on the genesis and function of “alphas”.

Highlights

► The review describes alpha activity in cognitive processes and cognitive impairment. ► Changes of alpha activity in processes of emotion and memory are described. ► It also outlines reasoning for understanding of alpha in integrative brain functions.

Section snippets

Alpha in functional cognitive states and memory

The statements “alpha is noise” and “alpha oscillations manifest the idling of the brain” were highly influential in the neuroscience literature until the mid-1990s, despite the resurgent interest in brain oscillations in the study of brain function. Most oscillation-related studies of cognitive processes focused on analysis of the gamma band. Since the focusing of studies to the gamma band for understanding of brain function is highly limited, a conference on functional correlates of alpha

Event-related alpha in emotion studies and analysis of complex signals

It is clear that the brain can perform a number of more difficult differentiations than those related to simple light, simple auditory signals and oddball strategy. We can differentiate a sea landscape from a mountain landscape; classical music from jazz music; a table from a tree. Recognition of known and unknown faces is the basic step. However, the task of face recognition also includes the recognition of facial expressions. In the analysis of facial expressions, we also confront another

Alpha in cognitive impairment

To date, many signal-processing techniques have been utilized to reveal pathological changes in spontaneous EEG associated with different brain pathologies. Spontaneous EEG Alpha activity was found to be lower in schizophrenia (Itil et al., 1972, Itil et al., 1974, Iacono, 1982, Miyauchi et al., 1990, Sponheim et al., 1994, Sponheim et al., 2000, Alfimova and Uvarova, 2008) and in Alzheimer's disease (Locatelli et al., 1998, Dunkin et al., 1994, Leuchter et al., 1987, Adler et al., 2003,

Reasonings and suggestions for understanding integrative functioning of alphas

As a consequence of the results surveyed in the present review, a chain of “Reasonings and Suggestions”, based on empirical evidence, will be outlined in the following section:

Concluding remarks and short synopsis

The brain is the most complex system in the known universe and, in both reviews, we presented empirical evidence related to the dynamics of the brain, i.e. a biological system that is continuously changing. Assuming that the brain is an organ, which also controls our mind and our body, the understanding of brain dynamics should help in the search for the communicative processes between the body and the brain. In addition to electrical oscillations, the brain–body machineries are also controlled

Acknowledgments

We thank Ms. Elif Tulay for carefully reading and correcting the manuscript, and Mrs. Melis Diktaş for her valuable secretarial help.

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