Interregional long-range and short-range synchrony: a basis for complex sensorimotor processing.

Communication of distant brain areas provides the basis for integration of complex information in order to adapt to changes in the environment, to process this information, and to generate appropriate behavioral responses necessary for successful behavior in daily life. How is interregional communication realized in the brain? Perceptions and actions are likely to be represented in the brain by large numbers of distributed neurons firing in synchrony. This synchronous activity of distributed neuronal networks can be noninvasively evaluated by multichannel surface electroencephalography (EEG) and the event-related analysis of synchronous EEG signals in the frequency domain. In this chapter we will discuss the role of interregional synchronous activity and its relevance as a mechanism for implementation of successful human complex behavior exemplified within studies of complex finger movements, context-dependent control of complex motor behavior, bimanual motor tasks, visuo-tactile integration, and recovery of motor functions after stroke. These studies provide evidence that synchronous interregional neuronal activity, determined by event-related synchronization (ERS) and desynchronization (ERD), task-related power increases (TRPI) and decreases (TRPD), and event- and task-related coherence (ERCoh, TRCoh) analysis, is one important mechanism for cortical implementation of successful human complex behavior and adaptation to changes in daily life. These results are discussed in the light of recent findings in animal models, substantiating the view of the relevance of interregional synchronous activity for information coding and control of behavior.