Multi-dimensional dynamics of human electromagnetic brain activity

Magnetoencephalography (meg) and electroencephalography (eeg) are invaluable neuroscientific tools for unveiling human neural dynamics in three dimensions (space,time,and frequency),which are associated with a wide variety of perceptions,cognition,and actions. meg/eeg also provides different categories of neuronal indices including activity magnitude,connectivity,and network properties along the three dimensions. in the last 20 years,interest has increased in inter-regional connectivity and complex network properties assessed by various sophisticated scientific analyses. we herein review the definition,computation,short history,and pros and cons of connectivity and complex network (graph-theory) analyses applied to meg/eeg signals. we briefly describe recent developments in source reconstruction algorithms essential for source-space connectivity and network analyses. furthermore,we discuss a relatively novel approach used in meg/eeg studies to examine the complex dynamics represented by human brain activity. the correct and effective use of these neuronal metrics provides a new insight into the multi-dimensional dynamics of the neural representations of various functions in the complex human brain. © 2016 kida,tanaka and kakigi.