The dual nature of alpha oscillations: Linking local rhythms to network function and dysfunction

Alpha oscillations are central to human brain function, yet their interpretation has traditionally focused on models of local inhibitory modulation. More recent findings, however, demonstrate a crucial role for alpha rhythms in network-level communication. This review integrates these perspectives, proposing that alpha rhythms regulate both the timing of local excitability and the alignment of excitability phases across the network, thereby enabling efficient information transmission. We summarize lifespan and clinical changes in alpha power, frequency, and connectivity, showing how these features reflect both the integrity of local oscillatory generators and the effectiveness of large-scale interactions. Coherence and travelling waves emerge as key markers linking these levels, capturing how excitability cycles are coordinated across the cortex. This integrated framework clarifies why alterations in alpha dynamics are sensitive indicators of dysfunction in aging, neurodegeneration, and brain injury. From a therapeutic perspective, traditional attempts to modulate alpha power alone may be insufficient, as they target local excitability without addressing network coordination. In contrast, coherence-based modulation may more effectively restore impaired communication dynamics. Neurofeedback studies demonstrating behavioral improvements following coherence training support this direction.