title: Alpha power indexes task-related networks on large and small scales: A multimodal ECoG study in humans and a non-human primate.
abstract: Performing different tasks, such as generating motor movements or processing sensory input, requires the recruitment of specific networks of neuronal populations. Previous studies suggested that power variations in the alpha band (8-12Hz) may implement such recruitment of task-specific populations by increasing cortical excitability in task-related areas while inhibiting population-level cortical activity in task-unrelated areas (Klimesch et al., 2007; Jensen and Mazaheri, 2010). However, the precise temporal and spatial relationships between the modulatory function implemented by alpha oscillations and population-level cortical activity remained undefined. Furthermore, while several studies suggested that alpha power indexes task-related populations across large and spatially separated cortical areas, it was largely unclear whether alpha power also differentially indexes smaller networks of task-related neuronal populations. Here we addressed these questions by investigating the temporal and spatial relationships of electrocorticographic (ECoG) power modulations in the alpha band and in the broadband gamma range (70-170Hz, indexing population-level activity) during auditory and motor tasks in five human subjects and one macaque monkey. In line with previous research, our results confirm that broadband gamma power accurately tracks task-related behavior and that alpha power decreases in task-related areas. More importantly, they demonstrate that alpha power suppression lags population-level activity in auditory areas during the auditory task, but precedes it in motor areas during the motor task. This suppression of alpha power in task-related areas was accompanied by an increase in areas not related to the task. In addition, we show for the first time that these differential modulations of alpha power could be observed not only across widely distributed systems (e.g., motor vs. auditory system), but also within the auditory system. Specifically, alpha power was suppressed in the locations within the auditory system that most robustly responded to particular sound stimuli. Altogether, our results provide experimental evidence for a mechanism that preferentially recruits task-related neuronal populations by increasing cortical excitability in task-related cortical areas and decreasing cortical excitability in task-unrelated areas. This mechanism is implemented by variations in alpha power and is common to humans and the non-human primate under study. These results contribute to an increasingly refined understanding of the mechanisms underlying the selection of the specific neuronal populations required for task execution.
authors.affiliation: Nat Ctr for Adapt Neurotech, Wadsworth Center, NY State Dept of Health, Albany, NY, USA; Dept of Biomed Sci, State Univ of New York at Albany, Albany, NY, USA. Electronic address: adepesters@neurotechcenter.org.
authors.forename: A
authors.initials: A
authors.lastname: de Pesters
authors.affiliation: Nat Ctr for Adapt Neurotech, Wadsworth Center, NY State Dept of Health, Albany, NY, USA. Electronic address: wcoon@neurotechcenter.org.
authors.forename: W G
authors.initials: WG
authors.lastname: Coon
authors.affiliation: Nat Ctr for Adapt Neurotech, Wadsworth Center, NY State Dept of Health, Albany, NY, USA; Dept of Neurology, Albany Medical College, Albany, NY, USA. Electronic address: pbrunner@neurotechcenter.org.
authors.forename: P
authors.initials: P
authors.lastname: Brunner
authors.affiliation: Dept of Biomed Eng, Univ of Florida, Gainesville, FL, USA. Electronic address: agunduz@bme.ufl.edu.
authors.forename: A
authors.initials: A
authors.lastname: Gunduz
authors.affiliation: Dept of Neurology, Albany Medical College, Albany, NY, USA. Electronic address: ritacca@mail.amc.edu.
authors.forename: A L
authors.initials: AL
authors.lastname: Ritaccio
authors.affiliation: SUNY Downstate Med Ctr, Brooklyn, NY, USA. Electronic address: nicolas.brunet@downstate.edu.
authors.forename: N M
authors.initials: NM
authors.lastname: Brunet
authors.affiliation: Dept of Cogn Neurosci, Maastricht Univ, Maastricht, Netherlands; Donders Inst for Brain, Cognition and Behaviour, Nijmegen, Netherlands. Electronic address: p.deweerd@maastrichtuniversity.nl.
authors.forename: P
authors.initials: P
authors.lastname: de Weerd
authors.affiliation: Donders Inst for Brain, Cognition and Behaviour, Nijmegen, Netherlands. Electronic address: mark.roberts@donders.ru.nl.
authors.forename: M J
authors.initials: MJ
authors.lastname: Roberts
authors.affiliation: Donders Inst for Brain, Cognition and Behaviour, Nijmegen, Netherlands. Electronic address: r.oostenveld@donders.ru.nl.
authors.forename: R
authors.initials: R
authors.lastname: Oostenveld
authors.affiliation: Donders Inst for Brain, Cognition and Behaviour, Nijmegen, Netherlands; Ernst Strüngmann Inst for Neurosci, Frankfurt, Germany. Electronic address: pascal.fries@esi-frankfurt.de.
authors.forename: P
authors.initials: P
authors.lastname: Fries
authors.affiliation: Nat Ctr for Adapt Neurotech, Wadsworth Center, NY State Dept of Health, Albany, NY, USA; Dept of Biomed Sci, State Univ of New York at Albany, Albany, NY, USA; Dept of Neurology, Albany Medical College, Albany, NY, USA. Electronic address: gschalk@neurotechcenter.org.
authors.forename: G
authors.initials: G
authors.lastname: Schalk
mesh_terms: D000328:Adult; D000513:Alpha Rhythm / Q000502:physiology*; D000818:Animals; D001931:Brain Mapping / Q000379:methods; D000071080:Cortical Excitability / Q000502:physiology*; D000069280:Electrocorticography / Q000379:methods*; D005260:Female; D065818:Gamma Rhythm / Q000502:physiology*; D006801:Humans; D008251:Macaca; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000502:physiology*; D062211:Spatio-Temporal Analysis; D013045:Species Specificity; D013647:Task Performance and Analysis
keywords: Alpha oscillations; Auditory processing; Broadband gamma; Electrocorticography (ECoG); Information gating