Neuromodulation of Neural Oscillations in Health and Disease

SIMPLE SUMMARY: Over the past few decades, advances in electroencephalography (EEG) recordings and brain stimulation has permitted an unprecedented view of how specific brain structures communicate as well as organize complex cognitive functions. Specifically, neurotransmitters (including norepinephrine, acetylcholine, and dopamine) have all been shown to have an impact on neural oscillations throughout the brain, linking them to changes in cognitive functions such as memory, attention, and executive function. While these interactions are still widely unexplored, their appearance in neurological disorders through cross-frequency coupling (CFC) brings light to the vital role they play in orchestrating healthy brain function. This brief review serves to highlight the important role each neuromodulatory system plays in changing widespread neural networks, emphasizing their involvement in health and disease to help inform more translational brain stimulation technologies. ABSTRACT: Using EEG and local field potentials (LFPs) as an index of large-scale neural activities, research has been able to associate neural oscillations in different frequency bands with markers of cognitive functions, goal-directed behavior, and various neurological disorders. While this gives us a glimpse into how neurons communicate throughout the brain, the causality of these synchronized network activities remains poorly understood. Moreover, the effect of the major neuromodulatory systems (e.g., noradrenergic, cholinergic, and dopaminergic) on brain oscillations has drawn much attention. More recent studies have suggested that cross-frequency coupling (CFC) is heavily responsible for mediating network-wide communication across subcortical and cortical brain structures, implicating the importance of neurotransmitters in shaping coordinated actions. By bringing to light the role each neuromodulatory system plays in regulating brain-wide neural oscillations, we hope to paint a clearer picture of the pivotal role neural oscillations play in a variety of cognitive functions and neurological disorders, and how neuromodulation techniques can be optimized as a means of controlling neural network dynamics. The aim of this review is to showcase the important role that neuromodulatory systems play in large-scale neural network dynamics, informing future studies to pay close attention to their involvement in specific features of neural oscillations and associated behaviors.