scholarly journals Dynamics of Alpha Control: Preparatory Suppression of Posterior Alpha Oscillations by Frontal Modulators Revealed with Combined EEG and Event-related Optical Signal

2014 ◽  
Vol 26 (10) ◽  
pp. 2400-2415 ◽  
Author(s):  
Kyle E. Mathewson ◽  
Diane M. Beck ◽  
Tony Ro ◽  
Edward L. Maclin ◽  
Kathy A. Low ◽  
...  
Keyword(s):  
Temporal Dynamics ◽  
Brain Activity ◽  
Conscious Experience ◽  
Optical Signal ◽  
Alpha Power ◽  
Top Down ◽  
Spatiotemporal Resolution ◽  
Attention Networks ◽  
Alpha Oscillations ◽  
Eeg Alpha

We investigated the dynamics of brain processes facilitating conscious experience of external stimuli. Previously, we proposed that alpha (8–12 Hz) oscillations, which fluctuate with both sustained and directed attention, represent a pulsed inhibition of ongoing sensory brain activity. Here we tested the prediction that inhibitory alpha oscillations in visual cortex are modulated by top–down signals from frontoparietal attention networks. We measured modulations in phase-coherent alpha oscillations from superficial frontal, parietal, and occipital cortices using the event-related optical signal (EROS), a measure of neuronal activity affording high spatiotemporal resolution, along with concurrently recorded EEG, while participants performed a visual target detection task. The pretarget alpha oscillations measured with EEG and EROS from posterior areas were larger for subsequently undetected targets, supporting alpha's inhibitory role. Using EROS, we localized brain correlates of these awareness-related alpha oscillations measured at the scalp to the cuneus and precuneus. Crucially, EROS alpha suppression correlated with posterior EEG alpha power across participants. Sorting the EROS data based on EEG alpha power quartiles to investigate alpha modulators revealed that suppression of posterior alpha was preceded by increased activity in regions of the dorsal attention network and decreased activity in regions of the cingulo-opercular network. Cross-correlations revealed the temporal dynamics of activity within these preparatory networks before posterior alpha modulation. The novel combination of EEG and EROS afforded localization of the sources and correlates of alpha oscillations and their temporal relationships, supporting our proposal that top–down control from attention networks modulates both posterior alpha and awareness of visual stimuli.

scholarly journals Spotting the path that leads nowhere: Modulation of human theta and alpha oscillations induced by trajectory changes during navigation

2018 ◽  
Author(s):  
Amir-Homayoun Javadi ◽  
Eva Zita Patai ◽  
Aaron Margois ◽  
Heng-Ru M. Tan ◽  
Darshan Kumaran ◽  
...  
Keyword(s):  
Temporal Dynamics ◽  
Brain Activity ◽  
Cognitive Map ◽  
Lava Flows ◽  
Neural Dynamics ◽  
Alpha Power ◽  
Neural Basis ◽  
Alpha Oscillations ◽  
Fine Grained ◽  
Desert Island

AbstractThe capacity to take efficient detours and exploit novel shortcuts during navigation is thought to be supported by a cognitive map of the environment. Despite advances in understanding the neural basis of the cognitive map, little is known about the neural dynamics associated with detours and shortcuts. Here, we recorded magnetoencephalography from humans as they navigated a virtual desert island riven by shifting lava flows. The task probed their ability to take efficient detours and shortcuts to remembered goals. We report modulation in event-related fields and theta power as participants identified real shortcuts and differentiated these from false shortcuts that led along suboptimal paths. Additionally, we found that a decrease in alpha power preceded ‘back-tracking’ where participants spontaneously turned back along a previous path. These findings help advance our understanding of the fine-grained temporal dynamics of human brain activity during navigation and support the development of models of brain networks that support navigation.

scholarly journals Three times NO: no relationship between frontal alpha asymmetry and depressive disorders in a multiverse analysis of three studies

2020 ◽  
Author(s):  
Aleksandra Kołodziej ◽  
Mikołaj Magnuski ◽  
Anastasia Ruban ◽  
Aneta Brzezicka
Keyword(s):  
Data Analysis ◽  
Analytical Approach ◽  
Depressive Disorders ◽  
Alpha Power ◽  
Alpha Oscillations ◽  
Alpha Asymmetry ◽  
Eeg Data ◽  
Theoretical Assumptions ◽  
Frontal Alpha Asymmetry ◽  
Eeg Alpha

AbstractFor decades, the frontal alpha asymmetry (FAA) - a disproportion in EEG alpha oscillations power between right and left frontal channels - has been one of the most popular measures of depressive disorders (DD) in electrophysiology studies. Patients with DD often manifest a left-sided FAA: relatively higher alpha power in the left versus right frontal lobe. Recently, however, multiple studies failed to confirm this effect, questioning its reproducibility. Our purpose is to thoroughly test the validity of FAA in depression by conducting a multiverse analysis - running many related analyses and testing the sensitivity of the effect to changes in the analytical approach - on data from three independent studies. Only two of the 81 analyses revealed significant results. We conclude the paper by discussing theoretical assumptions underlying the FAA and suggest a list of guidelines for improving and expanding the EEG data analysis in future FAA studies.

scholarly journals Age-dependent electroencephalogram (EEG) patterns during sevoflurane general anesthesia in infants

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Laura Cornelissen ◽  
Seong-Eun Kim ◽  
Patrick L Purdon ◽  
Emery N Brown ◽  
Charles B Berde
Keyword(s):  
General Anesthesia ◽  
Temporal Dynamics ◽  
Brain Activity ◽  
Body Movement ◽  
Video Recording ◽  
Brain State ◽  
Alpha Power ◽  
State Monitoring ◽  
Spatio Temporal ◽  
Electroencephalogram Eeg

Electroencephalogram (EEG) approaches may provide important information about developmental changes in brain-state dynamics during general anesthesia. We used multi-electrode EEG, analyzed with multitaper spectral methods and video recording of body movement to characterize the spatio-temporal dynamics of brain activity in 36 infants 0–6 months old when awake, and during maintenance of and emergence from sevoflurane general anesthesia. During maintenance: (1) slow-delta oscillations were present in all ages; (2) theta and alpha oscillations emerged around 4 months; (3) unlike adults, all infants lacked frontal alpha predominance and coherence. Alpha power was greatest during maintenance, compared to awake and emergence in infants at 4–6 months. During emergence, theta and alpha power decreased with decreasing sevoflurane concentration in infants at 4–6 months. These EEG dynamic differences are likely due to developmental factors including regional differences in synaptogenesis, glucose metabolism, and myelination across the cortex. We demonstrate the need to apply age-adjusted analytic approaches to develop neurophysiologic-based strategies for pediatric anesthetic state monitoring.

scholarly journals Attention and Temporal Expectations Modulate Power, Not Phase, of Ongoing Alpha Oscillations

2015 ◽  
Vol 27 (8) ◽  
pp. 1573-1586 ◽  
Author(s):  
Rosanne M. van Diepen ◽  
Michael X Cohen ◽  
Damiaan Denys ◽  
Ali Mazaheri
Keyword(s):  
Phase Angle ◽  
Phase Locking ◽  
Auditory Target ◽  
Alpha Power ◽  
Visual Condition ◽  
Top Down ◽  
Alpha Oscillations ◽  
Alpha Oscillation ◽  
Sensory Cortices ◽  
Phase Angles

The perception of near-threshold visual stimuli has been shown to depend in part on the phase (i.e., time in the cycle) of ongoing alpha (8–13 Hz) oscillations in the visual cortex relative to the onset of that stimulus. However, it is currently unknown whether the phase of the ongoing alpha activity can be manipulated by top–down factors such as attention or expectancy. Using three variants of a cross-modal attention paradigm with constant predictable stimulus onsets, we examined if cues signaling to attend to either the visual or the auditory domain influenced the phase of alpha oscillations in the associated sensory cortices. Importantly, intermixed in all three experiments, we included trials without a target to estimate the phase at target presentation without contamination from the early evoked responses. For these blank trials, at the time of expected target and distractor onset, we examined (1) the degree of the uniformity in phase angles across trials, (2) differences in phase angle uniformity compared with a pretarget baseline, and (3) phase angle differences between visual and auditory target conditions. Across all three experiments, we found that, although the cues induced a modulation in alpha power in occipital electrodes, neither the visual condition nor the auditory cue condition induced any significant phase-locking across trials during expected target or distractor presentation. These results suggest that, although alpha power can be modulated by top–down factors such as attention and expectation, the phase of the ongoing alpha oscillation is not under such control.

scholarly journals Prefrontal cortex modulates posterior alpha oscillations during top-down guided visual perception

2017 ◽  
Vol 114 (35) ◽  
pp. 9457-9462 ◽  
Author(s):  
Randolph F. Helfrich ◽  
Melody Huang ◽  
Guy Wilson ◽  
Robert T. Knight
Keyword(s):  
Visual Perception ◽  
Alpha Activity ◽  
Alpha Power ◽  
Top Down ◽  
Visual Stream ◽  
Alpha Oscillations ◽  
Fine Grained ◽  
Oscillatory Dynamics ◽  
Delta Activity ◽  
And Behavior

Conscious visual perception is proposed to arise from the selective synchronization of functionally specialized but widely distributed cortical areas. It has been suggested that different frequency bands index distinct canonical computations. Here, we probed visual perception on a fine-grained temporal scale to study the oscillatory dynamics supporting prefrontal-dependent sensory processing. We tested whether a predictive context that was embedded in a rapid visual stream modulated the perception of a subsequent near-threshold target. The rapid stream was presented either rhythmically at 10 Hz, to entrain parietooccipital alpha oscillations, or arrhythmically. We identified a 2- to 4-Hz delta signature that modulated posterior alpha activity and behavior during predictive trials. Importantly, delta-mediated top-down control diminished the behavioral effects of bottom-up alpha entrainment. Simultaneous source-reconstructed EEG and cross-frequency directionality analyses revealed that this delta activity originated from prefrontal areas and modulated posterior alpha power. Taken together, this study presents converging behavioral and electrophysiological evidence for frontal delta-mediated top-down control of posterior alpha activity, selectively facilitating visual perception.

Prestimulus Neural Oscillations Inhibit Visual Perception via Modulation of Response Gain

2014 ◽  
Vol 26 (11) ◽  
pp. 2514-2529 ◽  
Author(s):  
Maximilien Chaumon ◽  
Niko A. Busch
Keyword(s):  
Brain Activity ◽  
Sensory Information ◽  
Inhibitory Effect ◽  
Qualitative Description ◽  
Alpha Power ◽  
Alpha Oscillations ◽  
External Stimuli ◽  
Functional Mechanisms ◽  
The Brain ◽  
Output Transformation

The ongoing state of the brain radically affects how it processes sensory information. How does this ongoing brain activity interact with the processing of external stimuli? Spontaneous oscillations in the alpha range are thought to inhibit sensory processing, but little is known about the psychophysical mechanisms of this inhibition. We recorded ongoing brain activity with EEG while human observers performed a visual detection task with stimuli of different contrast intensities. To move beyond qualitative description, we formally compared psychometric functions obtained under different levels of ongoing alpha power and evaluated the inhibitory effect of ongoing alpha oscillations in terms of contrast or response gain models. This procedure opens the way to understanding the actual functional mechanisms by which ongoing brain activity affects visual performance. We found that strong prestimulus occipital alpha oscillations—but not more anterior mu oscillations—reduce performance most strongly for stimuli of the highest intensities tested. This inhibitory effect is best explained by a divisive reduction of response gain. Ongoing occipital alpha oscillations thus reflect changes in the visual system's input/output transformation that are independent of the sensory input to the system. They selectively scale the system's response, rather than change its sensitivity to sensory information.

The phase of prestimulus alpha oscillations affects tactile perception

2014 ◽  
Vol 111 (6) ◽  
pp. 1300-1307 ◽  
Author(s):  
Lei Ai ◽  
Tony Ro
Keyword(s):  
Brain Activity ◽  
Brain Regions ◽  
Stimulus Onset ◽  
Tactile Perception ◽  
Alpha Power ◽  
Perceptual Awareness ◽  
Alpha Oscillations ◽  
Left Hand ◽  
Tactile Stimuli ◽  
Significant Difference

Previous studies have shown that neural oscillations in the 8- to 12-Hz range influence sensory perception. In the current study, we examined whether both the power and phase of these mu/alpha oscillations predict successful conscious tactile perception. Near-threshold tactile stimuli were applied to the left hand while electroencephalographic (EEG) activity was recorded over the contralateral right somatosensory cortex. We found a significant inverted U-shaped relationship between prestimulus mu/alpha power and detection rate, suggesting that there is an intermediate level of alpha power that is optimal for tactile perception. We also found a significant difference in phase angle concentration at stimulus onset that predicted whether the upcoming tactile stimulus was perceived or missed. As has been shown in the visual system, these findings suggest that these mu/alpha oscillations measured over somatosensory areas exert a strong inhibitory control on tactile perception and that pulsed inhibition by these oscillations shapes the state of brain activity necessary for conscious perception. They further suggest that these common phasic processing mechanisms across different sensory modalities and brain regions may reflect a common underlying encoding principle in perceptual processing that leads to momentary windows of perceptual awareness.

Working Memory Processes Are Mediated by Local and Long-range Synchronization of Alpha Oscillations

2013 ◽  
Vol 25 (8) ◽  
pp. 1343-1357 ◽  
Author(s):  
Maite Crespo-Garcia ◽  
Diego Pinal ◽  
Jose L. Cantero ◽  
Fernando Díaz ◽  
Montserrat Zurrón ◽  
...  
Keyword(s):  
Working Memory ◽  
Long Range ◽  
Alpha Phase ◽  
Alpha Power ◽  
Phase Synchrony ◽  
Top Down ◽  
Alpha Oscillations ◽  
Memory Processes ◽  
Time Frequency ◽  
Cortical Regions

Different cortical dynamics of alpha oscillations (8–13 Hz) have been associated with increased working memory load, which have been mostly interpreted as a neural correlate of functional inhibition. This study aims at determining whether different manifestations of load-dependent amplitude and phase dynamics in the alpha band can coexist over different cortical regions. To address this question, we increased information load by manipulating the number and spatial configuration of domino spots. Time–frequency analysis of EEG source activity revealed (i) load-independent increases of both alpha power and interregional alpha-phase synchrony within task-irrelevant, posterior cortical regions and (ii) load-dependent decreases of alpha power over areas of the left pFC and bilateral posterior parietal cortex (PPC) preceded in time by load-dependent decreases of alpha-phase synchrony between the left pFC and the left PPC. The former results support the role of alpha oscillations in inhibiting irrelevant sensorimotor processing, whereas the latter likely reflect release of parietal task-relevant areas from top–down inhibition with load increase. This interpretation found further support in a significant latency shift of 15 msec from pFC to the PPC. Together, these results suggest that amplitude and phase alpha dynamics in both local and long-range cortical networks reflect different neural mechanisms of top–down control that might be crucial in mediating the different working memory processes.

scholarly journals Top–Down Cognitive Control in Students with a Rigid Set-on Facial Expression

2018 ◽  
Author(s):  
E Cheremushkin ◽  
N Petrenko
Keyword(s):  
Cognitive Control ◽  
Facial Expression ◽  
Emotional Facial Expression ◽  
Top Down ◽  
Alpha Oscillations ◽  
Fixed Set ◽  
Personal Anxiety ◽  
Eeg Alpha ◽  
Anxiety Depression ◽  
Rigid Set

Top–down cognitive control was studied in students by the model of fixed set for facial expression. In subjects with errors in the set fixing, it is weakened to the greatest extent. The hypothesis about the influence on the top–down cognitive control of the functional state of subjects caused by signs of autonomic dysfunction, personal anxiety, depression and sleep quality is considered. Keywords: top–down cognitive control, emotional facial expression, errors recognition, EEG, alpha oscillations

scholarly journals Cortical alpha oscillations in cochlear implant users reflect subjective listening effort during speech-in-noise perception

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0254162
Author(s):  
Brandon T. Paul ◽  
Joseph Chen ◽  
Trung Le ◽  
Vincent Lin ◽  
Andrew Dimitrijevic
Keyword(s):  
Cochlear Implant ◽  
Cochlear Implants ◽  
Inferior Frontal Gyrus ◽  
Alpha Power ◽  
Listening Effort ◽  
Left Inferior Frontal Gyrus ◽  
Alpha Oscillations ◽  
Speech In Noise ◽  
Eeg Alpha ◽  
Cortical Regions

Listening to speech in noise is effortful for individuals with hearing loss, even if they have received a hearing prosthesis such as a hearing aid or cochlear implant (CI). At present, little is known about the neural functions that support listening effort. One form of neural activity that has been suggested to reflect listening effort is the power of 8–12 Hz (alpha) oscillations measured by electroencephalography (EEG). Alpha power in two cortical regions has been associated with effortful listening—left inferior frontal gyrus (IFG), and parietal cortex—but these relationships have not been examined in the same listeners. Further, there are few studies available investigating neural correlates of effort in the individuals with cochlear implants. Here we tested 16 CI users in a novel effort-focused speech-in-noise listening paradigm, and confirm a relationship between alpha power and self-reported effort ratings in parietal regions, but not left IFG. The parietal relationship was not linear but quadratic, with alpha power comparatively lower when effort ratings were at the top and bottom of the effort scale, and higher when effort ratings were in the middle of the scale. Results are discussed in terms of cognitive systems that are engaged in difficult listening situations, and the implication for clinical translation.

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