New vistas for Alpha-frequency band oscillations

Neuroscience Center, University of Helsinki P.O. Box 56, FI-00014 University of Helsinki, Finland.
Trends in Neurosciences (Impact Factor: 13.56). 05/2007; 30(4):150-8. DOI: 10.1016/j.tins.2007.02.001
Source: PubMed


The amplitude of alpha-frequency band (8-14 Hz) activity in the human electroencephalogram is suppressed by eye opening, visual stimuli and visual scanning, whereas it is enhanced during internal tasks, such as mental calculation and working memory. alpha-Frequency band oscillations have hence been thought to reflect idling or inhibition of task-irrelevant cortical areas. However, recent data on alpha-amplitude and, in particular, alpha-phase dynamics posit a direct and active role for alpha-frequency band rhythmicity in the mechanisms of attention and consciousness. We propose that simultaneous alpha-, beta- (14-30 Hz) and gamma- (30-70 Hz) frequency band oscillations are required for unified cognitive operations, and hypothesize that cross-frequency phase synchrony between alpha, beta and gamma oscillations coordinates the selection and maintenance of neuronal object representations during working memory, perception and consciousness.

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Available from: Satu Palva,
    • "Data were filtered into the classic neurophysiological frequency ranges of theta (4–7 Hz), alpha (8–14 Hz), and beta (15–30 Hz). We focused on connectivity in these frequency ranges as interregional theta-and alpha-band synchronizations are understood to mediate large-scale network interactions, whereas gamma oscillations are increasingly thought to primarily be relevant for local neuronal activity (see Palva & Palva, 2007; von Stein & Sarnthein, 2000, for reviews) and, moreover, are more susceptible to contamination by artifacts in studies of taskdependent oscillatory dynamics (i.e., Yuval-Greenberg, Tomer, Kerenm, Nelken, & Deouell, 2008). More recent evidence has indicated that beta oscillations may also be pertinent for integrating local activity, mediated by gamma rhythms, into large-scale networks (Siegel, Donner, & Engel, 2012; Donner & Siegel, 2011). "
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    ABSTRACT: Synchronization of oscillations among brain areas is understood to mediate network communication supporting cognition, perception, and language. How task-dependent synchronization during word production develops throughout childhood and adolescence, as well as how such network coherence is related to the development of language abilities, remains poorly understood. To address this, we recorded magnetoencephalography while 73 participants aged 4-18 years performed a verb generation task. Atlas-guided source reconstruction was performed, and phase synchronization among regions was calculated. Task-dependent increases in synchronization were observed in the theta, alpha, and beta frequency ranges, and network synchronization differences were observed between age groups. Task-dependent synchronization was strongest in the theta band, as were differences between age groups. Network topologies were calculated for brain regions associated with verb generation and were significantly associated with both age and language abilities. These findings establish the maturational trajectory of network synchronization underlying expressive language abilities throughout childhood and adolescence and provide the first evidence for an association between large-scale neurophysiological network synchronization and individual differences in the development of language abilities.
    Journal of Cognitive Neuroscience 09/2015; DOI:10.1162/jocn_a_00879 · 4.09 Impact Factor
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    • ") . While variations in the posterior alpha band have been extensively studied , the underlying neural mechanisms remain controversial ( for review see Palva & Palva , 2007 ; Thut & Miniussi , 2009 ; Klimesch , 2012 "
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    ABSTRACT: Very little is known about plasticity in the adult visual cortex. In recent years psychophysical studies have shown that short-term monocular deprivation alters visual perception in adult humans. Specifically, after 150 minutes of monocular deprivation the deprived eye strongly dominates the dynamics of binocular rivalry, reflecting homeostatic plasticity. Here we investigate the neural mechanisms underlying this form of short-term visual cortical plasticity by measuring visual evoked potentials (VEPs) on the scalp of adult humans during monocular stimulation before and after 150 minutes of monocular deprivation. We found that monocular deprivation had opposite effect on the amplitude of the earliest component of the VEP (C1) for the deprived and non-deprived eye stimulation. C1 amplitude increased (+66%) for the deprived eye, while it decreased (-29%) for the non-deprived eye. Source localization analysis confirmed that the C1 originates in the primary visual cortex. We further report that following monocular deprivation, the amplitude of the peak of the evoked alpha spectrum increased on average of the 23% for the deprived eye and decreased on average of the 10% for the non-deprived eye, indicating a change in cortical excitability. These results indicate that a brief period of monocular deprivation alters interocular balance in the primary visual cortex of adult humans both by boosting activity of the deprived eye and by reducing activity of the non-deprived eye. This indicates a high level of residual homeostatic plasticity in the adult human primary visual cortex, likely mediated by a change of cortical excitability. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    The Journal of Physiology 06/2015; 593(19). DOI:10.1113/JP270950 · 5.04 Impact Factor
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    • "An experimental scenario was created where native Spanish speakers who were relatively proficient in English (i.e., foreign language) but had no knowledge of French (i.e., unknown language) completed a visual go/no-go task while different audio tracks including everyday conversations were being played in the background (a manipulation that was completely orthogonal to the main visual discrimination task). Because amplitude (power) and phase synchronization can reflect different neural processes (i.e., Palva & Palva, 2007), both were investigated here. Spectral power reflects local activations of large groups of neurons (Singer, 1999), indexing the resonance of the brain activity to the rhythms of speech (Buiatti, Peña, & Dehaene-Lambertz, 2009). "
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    ABSTRACT: Neuronal oscillations play a key role in auditory perception of verbal input, with the oscillatory rhythms of the brain showing synchronization with specific frequencies of speech. Here we investigated the neural oscillatory patterns associated with perceiving native, foreign, and unknown speech. Spectral power and phase synchronization were compared to those of a silent context. Power synchronization to native speech was found in frequency ranges corresponding to the theta band, while no synchronization patterns were found for the foreign speech context and the unknown language context. For phase synchrony, the native and unknown languages showed higher synchronization in the theta-band than the foreign language when compared to the silent condition. These results suggest that neural synchronization patterns are markedly different for native and foreign languages. Copyright © 2015 Elsevier Inc. All rights reserved.
    Brain and Language 05/2015; 147:51-57. DOI:10.1016/j.bandl.2015.05.008 · 3.22 Impact Factor
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