Investigating and Modulating Physiological and Pathological Brain Oscillations: The Role of Oscillatory Activity in Neural Plasticity

摘要

There is accumulating evidence that oscillatory activity plays a significant role in regulating brain function. Rhythmic phenomena are routinely observed during perception, motor, and cognitive tasks and have been implicated in altered functions across a broad range of diseases [ ]. Several studies suggest that the alpha rhythm gates information flow, beta inhibits changes in motor activity and is responsible for the maintenance of the current sensorimotor or cognitive state, and gamma reflects intracortical local synchronization [ – ]. However, so far, understanding of the contribution of these rhythms to human behaviour and the manifestation of symptoms in disease states is limited. Moreover, the relationship between brain oscillations and neural plasticity is not clear, although recent evidence supports a link. For instance, it has been demonstrated that resonant rhythms in sensorimotor areas modulate motor learning and enhanced high-gamma activity in the primary motor cortex influences LTP/LTD-like plastic mechanisms [ , , ]. As such we find ourselves in an era where we are rapidly garnering the tools to not only observe brain activity but also alter neural processes in a circumscribed manner. Such causal interactions allow deeper understanding of the role of neural oscillations in everyday life and of how changes in rhythmic activity can lead to altered functions in disease states. Noninvasive electrophysiological techniques such as high-density EEG and magnetoencephalography (MEG), invasive recordings of local field potentials, and advanced neuroimaging techniques able to infer brain oscillatory activity are now increasingly combined with different forms of brain stimulation [ , ]. Sensory rhythmic stimulation, transcranial magnetic stimulation (TMS), and transcranial alternating current stimulation (tACS), used alone or in combination, allow targeting and causally interacting with rhythmic brain activity [ – , ]. Also, EEG activity can be used to guide TMS in a closed-loop configuration so as to induce and/or interfere with specific brain states [ ]. These novel approaches provide new opportunities for drawing strong parallels between oscillatory activity and brain functions, including processes of cortical plasticity.