scholarly journals EEG Coherence Effects of Audio-Visual Stimulation (AVS) at Dominant and Twice Dominant Alpha Frequency

2005 ◽  
Vol 8 (4) ◽  
pp. 25-42 ◽  
Author(s):  
Jon Frederick ◽  
DeAnna Timmermann ◽  
Harold Russell ◽  
Joel Lubar
Keyword(s):  
Visual Stimulation ◽  
Eeg Coherence ◽  
Alpha Frequency ◽  
Coherence Effects

Visual Stimulus–Dependent Changes in Interhemispheric EEG Coherence in Ferrets

1999 ◽  
Vol 82 (6) ◽  
pp. 3082-3094 ◽  
Author(s):  
D. C. Kiper ◽  
M. G. Knyazeva ◽  
L. Tettoni ◽  
G. M. Innocenti
Keyword(s):  
Visual Field ◽  
Corpus Callosum ◽  
Experimental Validation ◽  
Visual Stimulation ◽  
Eeg Coherence ◽  
Vertical Meridian ◽  
Callosal Connections ◽  
Interhemispheric Coherence ◽  
Cortical Connections ◽  
Visual Areas

In recent years, the analysis of the coherence between signals recorded from the scalp [electroencephalographic (EEG) coherence] has been used to assess the functional properties of cortico-cortical connections, both in animal models and in humans. However, the experimental validation of this technique is still scarce. Therefore we applied it to the study of the callosal connections between the visual areas of the two hemispheres, because this particular set of cortico-cortical connections can be activated in a selective way by visual stimuli. Indeed, in primary and in low-order secondary visual areas, callosal axons interconnect selectively regions, which represent a narrow portion of the visual field straddling the vertical meridian and, within these regions, neurons that prefer the same stimulus orientation. Thus only isooriented stimuli located near the vertical meridian are expected to change interhemispheric coherence by activating callosal connections. Finally, if such changes are found and are indeed mediated by callosal connections, they should disappear after transection of the corpus callosum. We perfomed experiments on seven paralyzed and anesthetized ferrets, recording their cortical activity with epidural electrodes on areas 17/18, 19, and lateral suprasylvian, during different forms of visual stimulation. As expected, we found that bilateral iso-oriented stimuli near the vertical meridian, or extending across it, caused a significant increase in interhemispheric coherence in the EEG beta-gamma band. Stimuli with different orientations, stimuli located far from the vertical meridian, as well as unilateral stimuli failed to affect interhemispheric EEG coherence. The stimulus-induced increase in coherence disappeared after surgical transection of the corpus callosum. The results suggest that the activation of cortico-cortical connections can indeed be revealed as a change in EEG coherence. The latter can therefore be validly used to investigate the functionality of cortico-cortical connections.

scholarly journals Individual alpha frequency increases during a task but is unchanged by alpha-band flicker

2019 ◽  
Author(s):  
Michael J. Gray ◽  
Tatiana A. Emmanouil
Keyword(s):  
Visual Stimulation ◽  
Behavioral Measure ◽  
Neural Oscillations ◽  
Alpha Band ◽  
Frequency Bands ◽  
Alpha Frequency ◽  
Separate Source ◽  
Individual Alpha Frequency ◽  
Short Time ◽  
The Relationship

AbstractVisual perception fluctuates in-synch with ongoing neural oscillations in the delta, theta, and alpha frequency bands of the human EEG. Supporting the relationship between alpha and perceptual sampling, recent work has demonstrated that variations in individual alpha frequency (IAF) correlate with the ability to discriminate one from two stimuli presented briefly in the same location. Other studies have found that after being presented with a flickering stimulus at alpha frequencies, perception of near-threshold stimuli fluctuates for a short time at the same frequency. Motivated by previous work, we were interested in whether this alpha entrainment involves shifts in IAF. While recording EEG, we tested whether two-flash discrimination (a behavioral correlate of IAF) can be influenced by ∼1s of rhythmic visual stimulation at two different alpha frequencies (8.3hz and 12.5hz). Speaking against the bottom-up malleability of IAF, we found no change in IAF during stimulation and no change in two-flash discrimination immediately afterwards. We also found synchronous activity that persisted after 12.5hz stimulation, which suggests that a separate source of alpha was entrained. Importantly, we replicated the correlation between IAF and two-flash discrimination in a no-stimulation condition, demonstrating the sensitivity of our behavioral measure. We additionally found that IAF increased during the task compared to rest, which demonstrates that IAF is influenced by top-down factors but is not involved in entrainment. In the framework of existing findings, we suggest that visual entrainment may involve ongoing perceptually-relevant oscillations from the delta to alpha frequency bands, serving to maintain rhythmic temporal expectations.

The Effects of Bilateral Eye Movements on EEG Coherence When Recalling a Pleasant Memory

2014 ◽  
Vol 8 (3) ◽  
pp. 113-128 ◽  
Author(s):  
Brandon Keller ◽  
Larry Stevens ◽  
Colleen Lui ◽  
James Murray ◽  
Matthew Yaggie
Keyword(s):  
Eye Movements ◽  
Eye Movement ◽  
Functional Significance ◽  
Emotional Memory ◽  
Eeg Coherence ◽  
Processing Stage ◽  
Eyes Closed ◽  
Interhemispheric Coherence ◽  
Coherence Effects ◽  
The Right

In an investigation of the interhemispheric coherence (IhC) model for eye movement desensitization and reprocessing (EMDR) bilateral eye movement (BEM) effects, 30 participants were exposed to a stationary dot, a blinking red/green dot, or saccadic BEMs during the contemplation of a positive emotional memory. Electroencephalographies (EEGs) were measured afterward during an eyes-closed processing stage. Analyses revealed no significant IhC enhancement for the BEM condition but significant increases in Delta and Low Beta EEG intrahemispheric BEM coherence in the right and left frontal areas, respectively, and a trend increase in Right Frontal Low Beta BEM coherence. LORETA neuroimaging was employed to visually present significant amplitude changes corresponding to observed coherence effects. The functional significance of these intrahemispheric coherence effects is presented and a cortical coherence extension of the IhC model is suggested.

Bilateral Eye Movements and EEG Coherence During Positive Memories: Implications for PTSD and EMDR

2011 ◽  
Author(s):  
Brandon Keller ◽  
Larry C. Stevens ◽  
Kateryna Boyce ◽  
Colleen Lui ◽  
James Murray
Keyword(s):  
Eye Movements ◽  
Eeg Coherence ◽  
Positive Memories
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