Article

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: 12.9). 05/2007; 30(4):150-8. DOI: 10.1016/j.tins.2007.02.001
Source: PubMed

ABSTRACT 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.

Full-text

Available from: Satu Palva, Apr 24, 2015
1 Follower
 · 
209 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Background: With a life time prevalence estimated at 16%, major depression (MD) is a major public health issue. Previous studies have shown that depression has been associated with a variety of cognitive impairments. In addition to cognitive impairments, major depression is usually accompanied by alterations of cortical activity, especially in prefrontal areas. Recent studies have highlighted the importance of noninvasive brain stimulation as a means of modulating cortical excitability. Recent studies on major depression (MD) have revealed that transcranial direct current stimulation induces cortical excitability which facilitates memory and especially working memory. On the other hand visual aspects of memory in MD have not been yet investigated. Objective: This study aimed to investigate whether anodal and cathodal tDCS applied over dorsolateral prefrontal cortex (DLPFC), would significantly improve visual memory in patients with major depression. Methods: Thirty (N=30) patients with major depression were randomly assigned to receive either experimental(active) or control (sham) tDCS. The participants underwent a series of visual memory tasks before and after 10 sessions of tDCS. The parameters of active tDCS included 2 mA for 20 minutes per day for 10 consecutive days, anode over the left DLPFC (F3), cathode over the right DLPFC (F4) region. Results: After 10 sessions of anodal and cathodal tDCS, patients showed significantly improved performance in visual and spatial aspects of memory tasks. Specifically, anodal stimulation improved visual memory perfo rmance for the experimental group relative to baseline, whereas sham stimulation did not differentiate performance from baseline in the control group. Conclusion: This study showed that anodal tDCS over DLPFC concurrently with cathodal tDCS over right DLPFC improved visual and spatial aspects of memory in patients with MD. This finding is in generally consistent with previous findings about effectiveness of tDCS on cognition in major depression, while additionally provides support for effectiveness of tDCS on visual memory in MD. Keywords: Major depression, memory, tDCS, visual memory
    ISNR 22 nd ANNUAL CONFERENCE, SAN DIEGO, CA, USA, SAN DIEGO, CA, USA; 10/2014
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In recent years, schizophrenia research has focused on inhibitory interneuron dysfunction at the level of neurobiology and on cognitive impairments at the psychological level. Reviewing both experimental and computational findings, we show how the temporal structure of the activity of neuronal populations, exemplified by brain rhythms, can begin to bridge these levels of complexity. Oscillations in neuronal activity tie the pathophysiology of schizophrenia to alterations in local processing and large-scale coordination, and these alterations in turn can lead to the cognitive and perceptual disturbances observed in schizophrenia. Copyright © 2015 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.
    Biological psychiatry 02/2015; 27. DOI:10.1016/j.biopsych.2015.02.005 · 9.47 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A large amount of studies of the last decades revealed an association between human behavior and oscillatory activity in the human brain. Alike, abnormalities of oscillatory activity were related with pathological behavior in many neuropsychiatric disorders, such as in Parkinson's disease (PD) or in schizophrenia (SCZ). As a therapeutic tool, non-invasive brain stimulation (NIBS) has demonstrated the potential to improve behavioral performance in patients suffering from neuropsychiatric disorders. Since evidence accumulates that NIBS might be able to modulate oscillatory activity and related behavior in a scientific setting, this review focuses on discussing potential interventional strategies to target abnormalities in oscillatory activity in neuropsychiatric disorders. In particular, we will review oscillatory changes described in patients after stroke, with PD or suffering from SCZ. Potential ways of targeting interventionally the underlying pathological oscillations to improve related pathological behavior will be further discussed.
    Frontiers in Systems Neuroscience 01/2015; 9:33. DOI:10.3389/fnsys.2015.00033