Brain Oscillations and the Importance of Waveform Shape. Issue 2 (February 2017) - Cole, Scott R.
Abstract : Oscillations are a prevalent feature of brain recordings. They are believed to play key roles in neural communication and computation. Current analysis methods for studying neural oscillations often implicitly assume that the oscillations are sinusoidal. While these approaches have proven fruitful, we show here that there are numerous instances in which neural oscillations are nonsinusoidal. We highlight approaches to characterize nonsinusoidal features and account for them in traditional spectral analysis. Instead of being a nuisance, we discuss how these nonsinusoidal features may provide crucial and so far overlooked physiological information related to neural communication, computation, and cognition. Trends: The properties of neural oscillations are commonly correlated to disease or behavior states. These measures are mostly derived using traditional spectral analysis techniques that assume a sinusoidal basis. Electrical recordings from many brain regions, at multiple spatial scales, exhibit neural oscillations that are nonsinusoidal. New methods have been developed to quantify the nonsinusoidal features of oscillations and account for these features when using traditional spectral analysis. Features of oscillatory waveform shape have been related to physiological processes and behaviors. Manipulating the features of stimulation waveforms changes the effects of rhythmic electrical stimulation.