Modern vision of relationship between theta rhythm and the processes of attention

Abstract

At present time conceptions of complex neurophysiological mechanisms underlying processes of attention are actively developing. In last few years, several researches revealed rhythmic character of processes of attention. Especially theta-rhythm is considered to be significant in organization of rhythmic interactions between brain zones, which take part in providing attention systems work. The aim of the work – to analyze and summarize modern date about role of theta-rhythm in providing basic processes of attention. The report presents modern data about role of theta-rhythm in processes of attention. Specific features of attention systems are discussed. Thrifold model of attention, developed by Steven E. Petersen and Michael I. Posner is reviewed in detail. Moreover, evidences of rhythmic character of processes of attention are summarized and leading part of theta-activity in providing these processes is demonstrated. We also discuss the investigations by Randolph F. Helfrich and Ian C. Fiebelkorn et al. which stated that the quantization of processes of attention with theta-frequency as a general principle of brain structures activity. Dependence of frequency characteristics of cortex zones of human brain from number of objects of attention is discussed. There is also an analysis of theta-band’s ability to modulate biopotentials of higher frequency. Special attention is paid to the researches focused on theta-gamma coupling. The influence of theta-rhythm phase on gamma-rhythm amplitude in phase-amplitude coupling of theta- and gamma-band is analyzed. Theta-rhythm is considered to be one of the rhythmic components that regulate complex mental functions such as attention, memory and consciousness. Obviously, there is a lack of an exact understanding of the role for every band in mental functions regulation; therefore, more investigations in this field are required. However, several data about the role of theta-band in mental functions was collected. A complex of systems with different physiological and neurochemical basis provides attention. It was demonstrated that attention - is a rhythmical process in which theta-band is a crucial part. Theta-rhythm provides synchronization and joint activity of distant brain structures. Moreover, theta-rhythm modulates high-frequent bands. Theta- gamma-band coupling is supposed to be important for attention. Such cooperation is considered to be an evidence of cortical and subcortical zones and provides coordination of analyzing systems of different level. It is suggested that different phases of theta-band may provide retention/switching of attention or determine information flow. As a summary of review of literary sources, there is a conclusion about high significance of this frequency range in different attention systems functioning.