@article {3554,
	title = {Alpha power indexes task-related networks on large and small scales: A multimodal ECoG study in humans and a non-human primate.},
	journal = {NeuroImage},
	volume = {134},
	year = {2016},
	month = {Jul},
	pages = {122{\textendash}131},
	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.},
	issn = {1095-9572},
	doi = {10.1016/j.neuroimage.2016.03.074},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/27057960},
	author = {de Pesters, A. and Coon, W. G. and Peter Brunner and Gunduz, A. and A L Ritaccio and Brunet, N. M. and de Weerd, P. and Roberts, M. J. and Oostenveld, R. and Fries, P. and Gerwin Schalk}
}
@article {3553,
	title = {Oscillatory phase modulates the timing of neuronal activations and resulting behavior.},
	journal = {NeuroImage},
	volume = {133},
	year = {2016},
	month = {Jun},
	pages = {294{\textendash}301},
	abstract = {Human behavioral response timing is highly variable from trial to trial. While it is generally understood that behavioral variability must be due to trial-by-trial variations in brain function, it is still largely unknown which physiological mechanisms govern the timing of neural activity as it travels through networks of neuronal populations, and how variations in the timing of neural activity relate to variations in the timing of behavior. In our study, we submitted recordings from the cortical surface to novel analytic techniques to chart the trajectory of neuronal population activity across the human cortex in single trials, and found joint modulation of the timing of this activity and of consequent behavior by neuronal oscillations in the alpha band (8-12Hz). Specifically, we established that the onset of population activity tends to occur during the trough of oscillatory activity, and that deviations from this preferred relationship are related to changes in the timing of population activity and the speed of the resulting behavioral response. These results indicate that neuronal activity incurs variable delays as it propagates across neuronal populations, and that the duration of each delay is a function of the instantaneous phase of oscillatory activity. We conclude that the results presented in this paper are supportive of a general model for variability in the effective speed of information transmission in the human brain and for variability in the timing of human behavior.},
	issn = {1095-9572},
	doi = {10.1016/j.neuroimage.2016.02.080},
	url = {http://www.ncbi.nlm.nih.gov/pubmed/26975551},
	author = {Coon, W. G. and Gunduz, A. and Peter Brunner and A L Ritaccio and Pesaran, B. and Gerwin Schalk}
}
