Poster A117, Saturday, March 24, 1:30–3:30 pm, Exhibit Hall C
Systematic non-stationarity of alpha rhythms in the human brain: Long term frequency sliding and power changes
Christian Keitel1, Christopher SY Benwell1, Joachim Gross1, Gregor Thut1; 1University of Glasgow
An implicit assumption underlying current theories and the analysis techniques employed by many electro- & magnetoencephalographic (EEG/MEG) studies investigating neural oscillations is that, in the absence of experimental manipulation, the properties of a neural ‘oscillator’ measurable at the scalp remain approximately stationary over time. Here, across several EEG and MEG experiments, we show that these assumptions are false for one of the most prominent frequency bands, the alpha-band. Specifically, alpha power increases and instantaneous frequency decreases systematically over the course of a typical experimental session (~1-2 hours). Our results suggest the existence of two non-stationary endogenous processes inherent in alpha-band activity. Source-space analyses revealed that these processes may occur in partially overlapping cortical networks with a common right-lateralized focus along the ventral visual processing stream. As well as providing novel insight into the intrinsic properties of widespread neural networks, the findings are of fundamental importance for the analysis and interpretation of studies aimed at both identifying functionally relevant oscillatory networks, and also driving these networks through external entrainment.
Topic Area: ATTENTION: Other