Unraveling the Complex Origin of Brain Oscillations

Published on July 31, 2023

Imagine a lively carnival with various rides and attractions, all operating independently but contributing to the overall excitement. In a similar way, spontaneous low-frequency brain oscillations have multiple sources and origins. These oscillations, which play a crucial role in brain activity, have long puzzled scientists. To shed light on the underlying mechanism, a team of researchers combined optical imaging and electrophysiological recording techniques. By administering L-NAME to awake and anesthetized mice, they observed changes in the spectrum and synchronization of local field potential (LFP) signals. Interestingly, L-NAME triggered regular oscillations not only in LFP signals but also in hemodynamic signals. This discovery challenges the conventional belief that the frequency peak of hemodynamic signals should match that of LFP oscillations. To explain this mismatch, the researchers proposed a model of the neurovascular system. By unravelling the various sources and mechanisms behind brain oscillations, this study opens up new avenues for understanding the complexities of neural activity.

IntroductionSpontaneous low-frequency oscillations play a key role in brain activity. However, the underlying mechanism and origin of low-frequency oscillations remain under debate.MethodsOptical imaging and an electrophysiological recording system were combined to investigate spontaneous oscillations in the hemodynamic parameters and neuronal activity of awake and anesthetized mice after Nω-nitro-L-arginine methyl ester (L-NAME) administration.ResultsThe spectrum of local field potential (LFP) signals was significantly changed by L-NAME, which was further corroborated by the increase in energy and spatial synchronization. The important finding was that L-NAME triggered regular oscillations in both LFP signals and hemodynamic signals. Notably, the frequency peak of hemodynamic signals can be different from that of LFP oscillations in awake mice.DiscussionA model of the neurovascular system was proposed to interpret this mismatch of peak frequencies, supporting the view that spontaneous low-frequency oscillations arise from multiple sources.

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