scholarly journals Prestimulus alpha power is related to the strength of stimulus representation

Cortex ◽  
2020 ◽  
Vol 132 ◽  
pp. 250-257 ◽  
Author(s):  
Louise C. Barne ◽  
Floris P. de Lange ◽  
André M. Cravo
Keyword(s):  
Alpha Power ◽  
Stimulus Representation

scholarly journals Prestimulus alpha power is related to the strength of stimulus representation

2020 ◽  
Author(s):  
Louise C. Barne ◽  
Floris P. de Lange ◽  
André M. Cravo
Keyword(s):  
Spatial Attention ◽  
Pattern Analysis ◽  
Alpha Power ◽  
Multivariate Pattern Analysis ◽  
Stimulus Representation ◽  
Behavioural Performance ◽  
Stimulus Identity ◽  
Underlying Mechanisms ◽  
Multivariate Pattern

AbstractSpatial attention can modulate behavioural performance and is associated with several electrophysiological markers. In this study, we used multivariate pattern analysis in electrophysiology data to investigate the effects of covert spatial attention on the quality of stimulus processing and underlying mechanisms. Our results show that covert spatial attention led to (i) an anticipatory alpha power desynchronization; (ii) enhanced stimuli identity information. Moreover, we found that alpha power fluctuations in anticipation of the relevant stimuli boosted and prolonged the coding of stimulus identity.

Aberrant Sensorimotor Integration in Musicians' Cramp Patients

2003 ◽  
Vol 17 (4) ◽  
pp. 195-202 ◽  
Author(s):  
Vanessa K. Lim ◽  
John L. Bradshaw ◽  
Michael E.R. Nicholls ◽  
Ian J. Kirk ◽  
Jeff P. Hamm ◽  
...  
Keyword(s):  
Movement Disorder ◽  
Sensorimotor Cortex ◽  
Sensorimotor Integration ◽  
Group Interaction ◽  
Focal Dystonia ◽  
The Other ◽  
Alpha Power ◽  
Significant Group ◽  
Group Interactions

AbstractSimple tapping and complex movements (Luria finger apposition task) were performed unimanually and bimanually by two groups of professional guitarists while EEG was recorded from electrodes over the sensorimotor cortex. One group had a task-specific movement disorder (focal dystonia or musicians' cramp), while the other group did not (controls). There were no significant group interactions in the task-related power (TRPow) within the alpha range of 8-10Hz (mu1). In contrast, there was a significant group interaction within the alpha range of 10-12Hz (mu2); these latter frequencies are associated with task-specific sensorimotor integration. The significant group interaction included task (simple and complex) by hand (left, right, and both) by electrodes (10 electrodes over the sensorimotor areas). In the rest conditions, the alpha power (10-12Hz) was comparable between the groups; during movement, however, compared to the controls, patients demonstrated the greatest TRPow (10-12Hz) over all conditions. This was particularly evident when patients used their affected hand and suggests that patients with musicians' cramp have impaired task-specific sensorimotor integration.

scholarly journals Linking the Rapid Cascade of Visuo-Attentional Processes to Successful Memory Encoding

2020 ◽  
Author(s):  
B R Geib ◽  
R Cabeza ◽  
M G Woldorff
Keyword(s):  
Visual Processing ◽  
Memory Retrieval ◽  
Current Knowledge ◽  
High Temporal Resolution ◽  
Alpha Power ◽  
Attentional Orienting ◽  
Memory Encoding ◽  
Attentional Processes ◽  
Neural Processes ◽  
Dm Effect

Abstract While it is broadly accepted that attention modulates memory, the contribution of specific rapid attentional processes to successful encoding is largely unknown. To investigate this issue, we leveraged the high temporal resolution of electroencephalographic recordings to directly link a cascade of visuo-attentional neural processes to successful encoding: namely (1) the N2pc (peaking ~200 ms), which reflects stimulus-specific attentional orienting and allocation, (2) the sustained posterior-contralateral negativity (post-N2pc), which has been associated with sustained visual processing, (3) the contralateral reduction in oscillatory alpha power (contralateral reduction in alpha > 200 ms), which has also been independently related to attentionally sustained visual processing. Each of these visuo-attentional processes was robustly predictive of successful encoding, and, moreover, each enhanced memory independently of the classic, longer-latency, conceptually related, difference-due-to memory (Dm) effect. Early latency midfrontal theta power also promoted successful encoding, with at least part of this influence being mediated by the later latency Dm effect. These findings markedly expand current knowledge by helping to elucidate the intimate relationship between attentional modulations of perceptual processing and effective encoding for later memory retrieval.

scholarly journals EEG Measures of Value-Directed Strategic Processing in Older Adults With and Without Mild Cognitive Impairment

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 292-293
Author(s):  
Lydia Nguyen ◽  
Shraddha Shende ◽  
Daniel Llano ◽  
Raksha Mudar
Keyword(s):  
Older Adults ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Cognitive Aging ◽  
Spectral Power ◽  
Group Differences ◽  
Cognitive Resources ◽  
Alpha Power ◽  
Strategic Processing ◽  
Unique Word

Abstract Value-directed strategic processing is important for daily functioning. It allows selective processing of important information and inhibition of irrelevant information. This ability is relatively preserved in normal cognitive aging, but it is unclear if mild cognitive impairment (MCI) affects strategic processing and its underlying neurophysiological mechanisms. The current study examined behavioral and EEG spectral power differences between 16 cognitively normal older adults (CNOA; mean age: 74.5 ± 4.0 years) and 16 individuals with MCI (mean age: 77.1 ± 4.3 years) linked to a value-directed strategic processing task. The task used five unique word lists where words were assigned high- or low-value based on letter case and were presented sequentially while EEG was recorded. Participants were instructed to recall as many words as possible after each list to maximize their score. Results revealed no group differences in recall of low-value words, but individuals with MCI recalled significantly fewer high-value words and total number of words relative to CNOA. Group differences were observed in theta and alpha bands for low-value words, with greater synchronized theta power for CNOA than MCI and greater desynchronized alpha power for MCI than CNOA. Collectively, these findings demonstrate that more effortful neural processing of low-value words in the MCI group, relative to the CNOA group, allowed them to match their behavioral performance to the CNOA group. Individuals with MCI appear to utilize more cognitive resources to inhibit low-value information and might show memory-related benefits if taught strategies to focus on high-value information processing.

scholarly journals Theta and alpha power across fast and slow timescales in cognitive control

2021 ◽  
Author(s):  
Pieter Huycke ◽  
Pieter Verbeke ◽  
C. Nico Boehler ◽  
Tom Verguts
Keyword(s):  
Cognitive Control ◽  
Alpha Power

scholarly journals New Method for Generating New Families of Distributions

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 726
Author(s):  
Lamya A. Baharith ◽  
Wedad H. Aljuhani
Keyword(s):  
Exponential Distribution ◽  
Real Data ◽  
Rate Function ◽  
New Method ◽  
Likelihood Method ◽  
Alpha Power ◽  
Unknown Parameters ◽  
Failure Rate Function ◽  
New Approach ◽  
Numerical Studies

This article presents a new method for generating distributions. This method combines two techniques—the transformed—transformer and alpha power transformation approaches—allowing for tremendous flexibility in the resulting distributions. The new approach is applied to introduce the alpha power Weibull—exponential distribution. The density of this distribution can take asymmetric and near-symmetric shapes. Various asymmetric shapes, such as decreasing, increasing, L-shaped, near-symmetrical, and right-skewed shapes, are observed for the related failure rate function, making it more tractable for many modeling applications. Some significant mathematical features of the suggested distribution are determined. Estimates of the unknown parameters of the proposed distribution are obtained using the maximum likelihood method. Furthermore, some numerical studies were carried out, in order to evaluate the estimation performance. Three practical datasets are considered to analyze the usefulness and flexibility of the introduced distribution. The proposed alpha power Weibull–exponential distribution can outperform other well-known distributions, showing its great adaptability in the context of real data analysis.

scholarly journals Conscious perception and perceptual echoes: a binocular rivalry study

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Canhuang Luo ◽  
Rufin VanRullen ◽  
Andrea Alamia
Keyword(s):  
Binocular Rivalry ◽  
Visual Information ◽  
Visual Stimulation ◽  
Brain Regions ◽  
Travelling Wave ◽  
Alpha Power ◽  
Conscious Perception ◽  
Impulse Response Functions ◽  
Band Frequency ◽  
Underlying Mechanisms

Abstract Alpha rhythms (∼10Hz) in the human brain are classically associated with idling activities, being predominantly observed during quiet restfulness with closed eyes. However, recent studies demonstrated that alpha (∼10Hz) rhythms can directly relate to visual stimulation, resulting in oscillations, which can last for as long as one second. This alpha reverberation, dubbed perceptual echoes (PE), suggests that the visual system actively samples and processes visual information within the alpha-band frequency. Although PE have been linked to various visual functions, their underlying mechanisms and functional role are not completely understood. In this study, we investigated the relationship between conscious perception and the generation and the amplitude of PE. Specifically, we displayed two coloured Gabor patches with different orientations on opposite sides of the screen, and using a set of dichoptic mirrors, we induced a binocular rivalry between the two stimuli. We asked participants to continuously report which one of two Gabor patches they consciously perceived, while recording their EEG signals. Importantly, the luminance of each patch fluctuated randomly over time, generating random sequences from which we estimated two impulse-response functions (IRFs) reflecting the PE generated by the perceived (dominant) and non-perceived (suppressed) stimulus, respectively. We found that the alpha power of the PE generated by the consciously perceived stimulus was comparable with that of the PE generated during monocular vision (control condition) and higher than the PE induced by the suppressed stimulus. Moreover, confirming previous findings, we found that all PEs propagated as a travelling wave from posterior to frontal brain regions, irrespective of conscious perception. All in all our results demonstrate a correlation between conscious perception and PE, suggesting that the synchronization of neural activity plays an important role in visual sampling and conscious perception.

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