From Laboratory for Clinical Neuroscience Centre for Biomedical Technology
Universidad Politécnica de Madrid
Presenting a talk entitled
Alpha (and gamma) oscillatory modulations underlying working memory and visual perception
Abstract
The posterior alpha(8–13 Hz) rhythm is by far the strongest spectral fingerprint in the human brain. Almost 90 years later, its physiological origin and functional role are topics under vigorous debate. On one side, there is the “alpha reflects functional inhibition” mantra (Jensen & Mazaheri 2010; Jensen et al 2014) that suggests that alpha oscillations are non-sinunoidal waves that produce prominent inhibitory pulses in task-irrelevant brain regions. Another critical assumption is that the physiological origin of alpha is inhibitory, that is, generated by inhibitory interneurons (functiontal inhibition ~ physiological inhibition). On the other side, other accounts embrace the opposite framework: alpha oscillations would exert an active role in information processing over task-relevant brain regions (Palva & Palva, 2007; 2011; VanRullen 2016). However, both frameworks predict strong cross-frequency coupling (CFC) with gamma in order to communicate information between and within brain regions. In this seminar I will present three studies that show that a) alpha oscillations can perform functional inhibition through physiological excitation, b) a sizable part of the CFC between alpha-beta/gamma can be explained due to the well-known non-sinusoidal properties of the alpha oscillations and c) the posterior alpha can actively propagate stimulus-related information as a travelling wave. These studies taken together with recent evidence (Foster & Awh 2018) suggest that the two frameworks are partially right. In addition, there may be multiple alpha sources that perform, simultaneously, complementary functions such as functional inhibition and active processing.
 |