scholarly journals Pinging the brain with visual impulses reveals electrically active, not activity-silent, working memories

PLoS Biology ◽  
2021 ◽  
Vol 19 (10) ◽  
pp. e3001436
Author(s):  
Joao Barbosa ◽  
Diego Lozano-Soldevilla ◽  
Albert Compte
Keyword(s):  
Working Memory ◽  
Statistical Power ◽  
Computational Models ◽  
Neuronal Firing ◽  
Memory Storage ◽  
Alpha Power ◽  
Eeg Data ◽  
Synaptic Changes ◽  
Biological Cost ◽  
The Relationship

Persistently active neurons during mnemonic periods have been regarded as the mechanism underlying working memory maintenance. Alternatively, neuronal networks could instead store memories in fast synaptic changes, thus avoiding the biological cost of maintaining an active code through persistent neuronal firing. Such “activity-silent” codes have been proposed for specific conditions in which memories are maintained in a nonprioritized state, as for unattended but still relevant short-term memories. A hallmark of this “activity-silent” code is that these memories can be reactivated from silent, synaptic traces. Evidence for “activity-silent” working memory storage has come from human electroencephalography (EEG), in particular from the emergence of decodability (EEG reactivations) induced by visual impulses (termed pinging) during otherwise “silent” periods. Here, we reanalyze EEG data from such pinging studies. We find that the originally reported absence of memory decoding reflects weak statistical power, as decoding is possible based on more powered analyses or reanalysis using alpha power instead of raw voltage. This reveals that visual pinging EEG “reactivations” occur in the presence of an electrically active, not silent, code for unattended memories in these data. This crucial change in the evidence provided by this dataset prompts a reinterpretation of the mechanisms of EEG reactivations. We provide 2 possible explanations backed by computational models, and we discuss the relationship with TMS-induced EEG reactivations.

scholarly journals Contralateral Delay Activity Tracks Fluctuations in Working Memory Performance

2018 ◽  
Vol 30 (9) ◽  
pp. 1229-1240 ◽  
Author(s):  
Kirsten C. S. Adam ◽  
Matthew K. Robison ◽  
Edward K. Vogel
Keyword(s):  
Working Memory ◽  
Individual Differences ◽  
Memory Load ◽  
Memory Performance ◽  
Memory Task ◽  
Memory Storage ◽  
Alpha Power ◽  
Working Memory Load ◽  
Contralateral Delay Activity ◽  
Trial Performance

Neural measures of working memory storage, such as the contralateral delay activity (CDA), are powerful tools in working memory research. CDA amplitude is sensitive to working memory load, reaches an asymptote at known behavioral limits, and predicts individual differences in capacity. An open question, however, is whether neural measures of load also track trial-by-trial fluctuations in performance. Here, we used a whole-report working memory task to test the relationship between CDA amplitude and working memory performance. If working memory failures are due to decision-based errors and retrieval failures, CDA amplitude would not differentiate good and poor performance trials when load is held constant. If failures arise during storage, then CDA amplitude should track both working memory load and trial-by-trial performance. As expected, CDA amplitude tracked load (Experiment 1), reaching an asymptote at three items. In Experiment 2, we tracked fluctuations in trial-by-trial performance. CDA amplitude was larger (more negative) for high-performance trials compared with low-performance trials, suggesting that fluctuations in performance were related to the successful storage of items. During working memory failures, participants oriented their attention to the correct side of the screen (lateralized P1) and maintained covert attention to the correct side during the delay period (lateralized alpha power suppression). Despite the preservation of attentional orienting, we found impairments consistent with an executive attention theory of individual differences in working memory capacity; fluctuations in executive control (indexed by pretrial frontal theta power) may be to blame for storage failures.

scholarly journals The impact of retro-cue validity on working memory representation: Evidence from electroencephalograms

2020 ◽  
Author(s):  
Xueying Fu ◽  
Chaoxiong Ye ◽  
huzhonghua ◽  
Tengfei Liang ◽  
Ziyuan Li ◽  
...  
Keyword(s):  
Working Memory ◽  
Spatial Attention ◽  
Memory Storage ◽  
Time Interval ◽  
Memory Representation ◽  
Attention And Memory ◽  
Alpha Power ◽  
Cue Validity ◽  
Validity Condition ◽  
The Impact

Memory performance can be improved by retrospectively cueing an item maintained in visual working memory (VWM). Different hypotheses have been proposed to explain the mechanisms behind retro-cueing and VWM. Previous behavioral studies suggest that different retro-cue validities may lead individuals to implement retro-cues in different ways to obtain a retro-cue effect. However, there is still no clear electroencephalogram (EEG) evidence to support that the retro-cue effect under different validity conditions is triggered by different mechanisms. Herein, we investigated whether retro-cue validity modulated the mechanisms underlying the retro-cue effect in VWM by using EEGs. We manipulated retro-cue validity by using blocks in a color change detection task. Contralateral delay activity (CDA) and lateralized alpha power were used assess spatial attention and memory storage, respectively. Significant retro-cue effects were observed under both high- and low-validity conditions. More importantly, although the retro-cue could redirect spatial attention under both high- and low-validity conditions, we found that participants maintained the non-cued items during a measured time interval under the low-validity condition, but dropped them out of VWM under the high-validity condition. Our results resolve previous contradictory findings. The retro-cue effect in our study can be explained by the removal hypothesis, prioritization hypothesis, and protection-during-retrieval hypothesis. This work suggests that the mechanisms underlying the retro-cue effect are not mutually exclusive, but determined by the cue validity. Individuals can voluntarily choose different mechanisms based on the expected retro-cue validity.

Impact of Experimental Modulation of EEG Alpha Power on Visual Working Memory Storage in Healthy Participants

2020 ◽  
Vol 87 (9) ◽  
pp. S403 ◽  
Author(s):  
Molly Erickson ◽  
Dillon Smith ◽  
Laura Crespo ◽  
Steven Silverstein
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
Memory Storage ◽  
Alpha Power ◽  
Eeg Alpha ◽  
Healthy Participants

scholarly journals Neural evidence for categorical biases in working memory for location and orientation

2020 ◽  
Author(s):  
Gi-Yeul Bae
Keyword(s):  
Working Memory ◽  
Computational Models ◽  
Spatial Working Memory ◽  
Memory Representation ◽  
Response Preparation ◽  
Behavioral Measures ◽  
Eeg Data ◽  
Categorical Structure ◽  
Memory Representations ◽  
Preparation Strategy

AbstractPrevious research demonstrated that visual working memory exhibits biases with respect to the categorical structure of the stimulus space. However, a majority of those studies used behavioral measures of working memory, and it is not clear whether the working memory representations per se are influenced by the categorical structure or whether the biases arise in decision or response processes during the report. Here, I applied a multivariate decoding technique to EEG data collected during working memory tasks to determine whether neural activity associated with the working memory representation is categorically biased prior to the report. I found that the decoding of spatial working memory was biased away from the nearest cardinal location, consistent with the biases observed in the behavioral responses. In a follow-up experiment which was designed to prevent the use of a response preparation strategy, I found that the decoding still exhibited categorical biases. Together, these results provide neural evidence that working memory representations themselves are categorically biased, imposing important constraints on the computational models of working memory representations.

scholarly journals Enabling #EEGManyLabs: Quality in Automatically Preprocessed EEG Data and Psychopathological Associations of Frontal Alpha Asymmetry

2022 ◽  
Author(s):  
Niklas Schürmann
Keyword(s):  
Interrater Reliability ◽  
Large Scale ◽  
Electrode Pair ◽  
Alpha Power ◽  
Alpha Asymmetry ◽  
Eeg Data ◽  
Replication Crisis ◽  
State Of Research ◽  
The Relationship

Neuroscience is facing a replication crisis. Little effort is invested in replication projects and low power in many studies indicates a potentially poor state of research. To assess replicability of EEG research, the #EEGManyLabs project aims to reproduce the most influential original EEG studies. A spin-off to the main project shall investigate the relationship between frontal alpha asymmetries and psychopathological symptoms, the predictive qualities of which have lately been considered controversial. To ensure that preprocessing of EEG data can be conducted automatically (via Automagic), we tested 47 healthy participants in an EEG resting state paradigm and collected psychopathological measures. We analyzed reliability and quality of manual and automated preprocessing and performed multiple regressions to investigate the association of frontal alpha asymmetries and depression, worry, trait anxiety and COVID-19 related worry. We hypothesized comparably good interrater reliability of preprocessing methods and higher data quality in automatically preprocessed data. We expected associations of leftward frontal alpha asymmetries and higher depression and anxiety scores and significant associations of rightward frontal alpha asymmetries and higher worrying and COVID-19- related worrying. Interrater reliability of preprocessing methods was mostly good, automatically preprocessed data achieved higher quality scores than manually preprocessed data. We uncovered an association of relative rightward lateralization of alpha power at one electrode pair and depressive symptoms. No further associations of interest emerged. We conclude that Automagic is an appropriate tool for large-scale preprocessing. Findings regarding associations of frontal alpha asymmetries and psychopathology likely stem from sample limitations and shrinking effect sizes.

Task-specific Disruptions in Theta Oscillations during Working Memory for Temporal Order in People with Schizophrenia

2020 ◽  
Vol 32 (11) ◽  
pp. 2117-2130 ◽  
Author(s):  
Xiaonan L. Liu ◽  
Charan Ranganath ◽  
Liang-Tien Hsieh ◽  
Mitzi Hurtado ◽  
Tara A. Niendam ◽  
...  
Keyword(s):  
Working Memory ◽  
Temporal Order ◽  
Theta Oscillations ◽  
Oscillatory Activity ◽  
Neural Oscillations ◽  
Alpha Power ◽  
Complex Objects ◽  
Impaired Performance ◽  
Theta Power ◽  
The Relationship

Prior studies demonstrated that neural oscillations are enhanced during working memory (WM) maintenance and that this activity can predict behavioral performance in healthy individuals. However, it is unclear whether the relationship holds for people with WM deficits. People with schizophrenia have marked WM deficits, and such deficits are most prominent when patients are required to process relationships between items, such as temporal order. Here, we used EEG to compare the relationship between oscillatory activity and WM performance in patients and controls. EEG was recorded as participants performed tasks requiring maintenance of complex objects (“Item”) or the temporal order of objects (“Order”). In addition to testing for group differences, we examined individual differences in EEG power and WM performance across groups. Behavioral results demonstrated that patients showed impaired performance on both Item and Order trials. EEG analyses revealed that patients showed an overall reduction in alpha power, but the relationship between alpha activity and performance was preserved. In contrast, patients showed a reduction in theta power specific to Order trials, and theta power could predict performance on Order trials in controls, but not in patients. These findings demonstrate that WM impairments in patients may reflect two different processes: a general deficit in alpha oscillations and a specific deficit in theta oscillations when temporal order information must be maintained. At a broader level, the results highlight the value of characterizing brain–behavior relationships, by demonstrating that the relationship between neural oscillations and WM performance can be fundamentally disrupted in those with WM deficits.

scholarly journals The Contralateral Delay Activity Tracks the Sequential Loading of Objects into Visual Working Memory, Unlike Lateralized Alpha Oscillations

2019 ◽  
Vol 31 (11) ◽  
pp. 1689-1698 ◽  
Author(s):  
Sisi Wang ◽  
Jason Rajsic ◽  
Geoffrey F. Woodman
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
Human Subjects ◽  
Neural Mechanisms ◽  
Memory Storage ◽  
Alpha Power ◽  
Alpha Oscillations ◽  
Contralateral Delay Activity ◽  
Continuous Stream ◽  
Additional Object

Visual working memory temporarily represents a continuous stream of task-relevant objects as we move through our environment performing tasks. Previous work has identified candidate neural mechanisms of visual working memory storage; however, we do not know which of these mechanisms enable the storage of objects as we sequentially encounter them in our environment. Here, we measured the contralateral delay activity (CDA) and lateralized alpha oscillations as human subjects were shown a series of objects that they needed to remember. The amplitude of CDA increased following the presentation of each to-be-remembered object, reaching asymptote at about three to four objects. In contrast, the concurrently measured lateralized alpha power remained constant with each additional object. Our results suggest that the CDA indexes the storage of objects in visual working memory, whereas lateralized alpha suppression indexes the focusing of attention on the to-be-remembered objects.

The Relation Between Aerobic Fitness and Cognitive Performance

2016 ◽  
Vol 30 (3) ◽  
pp. 102-113 ◽  
Author(s):  
Chun-Hao Wang ◽  
Chun-Ming Shih ◽  
Chia-Liang Tsai
Keyword(s):  
Cognitive Performance ◽  
Aerobic Fitness ◽  
Reaction Times ◽  
Mediation Model ◽  
Brain Potentials ◽  
Fitness Level ◽  
Eeg Data ◽  
Attention Performance ◽  
P3 Amplitude ◽  
The Relationship

Abstract. This study aimed to assess whether brain potentials have significant influences on the relationship between aerobic fitness and cognition. Behavioral and electroencephalographic (EEG) data was collected from 48 young adults when performing a Posner task. Higher aerobic fitness is related to faster reaction times (RTs) along with greater P3 amplitude and shorter P3 latency in the valid trials, after controlling for age and body mass index. Moreover, RTs were selectively related to P3 amplitude rather than P3 latency. Specifically, the bootstrap-based mediation model indicates that P3 amplitude mediates the relationship between fitness level and attention performance. Possible explanations regarding the relationships among aerobic fitness, cognitive performance, and brain potentials are discussed.

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