Dynamics of Dynamics within a Single Data Acquisition Session: Variation in Neocortical Alpha Oscillations in Human MEG

Qian Wan,Christopher Moore,Catherine Kerr,Matti Hämäläinen,Dominique Pritchett,Stephanie Jones,Joseph Najbauer

doi:10.1371/journal.pone.0024941

Abstract

BackgroundBehavioral paradigms applied during human recordings in electro- and magneto- encephalography (EEG and MEG) typically require 1–2 hours of data collection. Over this time scale, the natural fluctuations in brain state or rapid learning effects could impact measured signals, but are seldom analyzed.Methods and FindingsWe investigated within-session dynamics of neocortical alpha (7–14 Hz) rhythms and their allocation with cued-attention using MEG recorded from primary somatosensory neocortex (SI) in humans. We found that there were significant and systematic changes across a single ∼1 hour recording session in several dimensions, including increased alpha power, increased differentiation in attention-induced alpha allocation, increased distinction in immediate time-locked post-cue evoked responses in SI to different visual cues, and enhanced power in the immediate cue-locked alpha band frequency response. Further, comparison of two commonly used baseline methods showed that conclusions on the evolution of alpha dynamics across a session were dependent on the normalization method used.ConclusionsThese findings are important not only as they relate to studies of oscillations in SI, they also provide a robust example of the type of dynamic changes in brain measures within a single session that are overlooked in most human brain imaging/recording studies.

Highlights

Oscillatory dynamics in neocortex are thought to be important correlates of neurological states such as arousal [1], attention [2,3,4,5,6], sensory perception [7,8,9,10], memory processes [11,12], and readiness to learn [13]
These findings are important as they relate to studies of oscillations in SI, they provide a robust example of the type of dynamic changes in brain measures within a single session that are overlooked in most human brain imaging/recording studies
Preliminary analysis suggested that neocortical dynamics were more consistent across subjects at the end of an experimental session [2,27]

Summary

Introduction

Oscillatory dynamics in neocortex are thought to be important correlates of neurological states such as arousal [1], attention [2,3,4,5,6], sensory perception [7,8,9,10], memory processes [11,12], and readiness to learn [13]. Behavioral paradigms applied during human recordings in electro- and magneto- encephalography (EEG and MEG) typically require 1–2 hours of data collection Over this time scale, the natural fluctuations in brain state or rapid learning effects could impact measured signals, but are seldom analyzed

Methods

Results

Conclusion