scholarly journals The role of alpha power in the suppression of anticipated distractors during verbal working memory

2020 ◽  
Author(s):  
Sabrina Sghirripa ◽  
Lynton Graetz ◽  
Ashley Merkin ◽  
Nigel C Rogasch ◽  
Michael C Ridding ◽  
...  

AbstractAs working memory (WM) is limited in capacity, it is important to direct neural resources towards processing task-relevant information while ignoring distractors. Neural oscillations in the alpha frequency band (8-12 Hz) have been suggested to play a role in the inhibition of task-irrelevant information during WM, although results are mixed, possibly due to differences in the type of WM task employed. Here, we examined the role of alpha power in inhibition of anticipated distractors of varying strength using a modified Sternberg task where the encoding and retention periods were temporally separated. We recorded EEG while 20 young adults completed the task and found: 1) slower reaction times in strong distractor trials compared to weak distractor trials; 2) increased alpha power in posterior regions from baseline prior to presentation of a distractor regardless of condition; and 3) no differences in alpha power between strong and weak distractor conditions. Our results suggest that parieto-occipital alpha power is increased prior to a distractor. However we could not find evidence that alpha power is further modulated by distractor strength.

2014 ◽  
Vol 111 (3) ◽  
pp. 481-487 ◽  
Author(s):  
Arezoo Pooresmaeili ◽  
Dominik R. Bach ◽  
Raymond J. Dolan

Deciding whether a stimulus is the “same” or “different” from a previous presented one involves integrating among the incoming sensory information, working memory, and perceptual decision making. Visual selective attention plays a crucial role in selecting the relevant information that informs a subsequent course of action. Previous studies have mainly investigated the role of visual attention during the encoding phase of working memory tasks. In this study, we investigate whether manipulation of bottom-up attention by changing stimulus visual salience impacts on later stages of memory-based decisions. In two experiments, we asked subjects to identify whether a stimulus had either the same or a different feature to that of a memorized sample. We manipulated visual salience of the test stimuli by varying a task-irrelevant feature contrast. Subjects chose a visually salient item more often when they looked for matching features and less often so when they looked for a nonmatch. This pattern of results indicates that salient items are more likely to be identified as a match. We interpret the findings in terms of capacity limitations at a comparison stage where a visually salient item is more likely to exhaust resources leading it to be prematurely parsed as a match.


2020 ◽  
Vol 32 (3) ◽  
pp. 558-569 ◽  
Author(s):  
Nicole Hakim ◽  
Tobias Feldmann-Wüstefeld ◽  
Edward Awh ◽  
Edward K. Vogel

Working memory maintains information so that it can be used in complex cognitive tasks. A key challenge for this system is to maintain relevant information in the face of task-irrelevant perturbations. Across two experiments, we investigated the impact of task-irrelevant interruptions on neural representations of working memory. We recorded EEG activity in humans while they performed a working memory task. On a subset of trials, we interrupted participants with salient but task-irrelevant objects. To track the impact of these task-irrelevant interruptions on neural representations of working memory, we measured two well-characterized, temporally sensitive EEG markers that reflect active, prioritized working memory representations: the contralateral delay activity and lateralized alpha power (8–12 Hz). After interruption, we found that contralateral delay activity amplitude momentarily sustained but was gone by the end of the trial. Lateralized alpha power was immediately influenced by the interrupters but recovered by the end of the trial. This suggests that dissociable neural processes contribute to the maintenance of working memory information and that brief irrelevant onsets disrupt two distinct online aspects of working memory. In addition, we found that task expectancy modulated the timing and magnitude of how these two neural signals responded to task-irrelevant interruptions, suggesting that the brain's response to task-irrelevant interruption is shaped by task context.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Zsuzsanna Fodor ◽  
Csilla Marosi ◽  
László Tombor ◽  
Gábor Csukly

Abstract Focusing attention on relevant information while ignoring distracting stimuli is essential to the efficacy of working memory. Alpha- and theta-band oscillations have been linked to the inhibition of anticipated and attentionally avoidable distractors. However, the neurophysiological background of the rejection of task-irrelevant stimuli appearing in the focus of attention is not fully understood. We aimed to examine whether theta and alpha-band oscillations serve as an indicator of successful distractor rejection. Twenty-four students were enrolled in the study. 64-channel EEG was recorded during a modified Sternberg working memory task where weak and strong (salient) distractors were presented during the retention period. Event-related spectral perturbation in the alpha frequency band was significantly modulated by the saliency of the distracting stimuli, while theta oscillation was modulated by the need for cognitive control. Moreover, stronger alpha desynchronization to strong relative to weak distracting stimuli significantly increased the probability of mistakenly identifying the presented distractor as a member of the memory sequence. Therefore, our results suggest that alpha activity reflects the vulnerability of attention to distracting salient stimuli.


2019 ◽  
Vol 31 (12) ◽  
pp. 1933-1945 ◽  
Author(s):  
Zhenhong Hu ◽  
Christopher M. Barkley ◽  
Susan E. Marino ◽  
Chao Wang ◽  
Abhijit Rajan ◽  
...  

Working memory capacity (WMC) measures the amount of information that can be maintained online in the face of distraction. Past work has shown that the efficiency with which the frontostriatal circuit filters out task-irrelevant distracting information is positively correlated with WMC. Recent work has demonstrated a role of posterior alpha oscillations (8–13 Hz) in providing a sensory gating mechanism. We investigated the relationship between memory load modulation of alpha power and WMC in two verbal working memory experiments. In both experiments, we found that posterior alpha power increased with memory load during memory, in agreement with previous reports. Across individuals, the degree of alpha power modulation by memory load was negatively associated with WMC, namely, the higher the WMC, the less alpha power was modulated by memory load. After the administration of topiramate, a drug known to affect alpha oscillations and have a negative impact on working memory function, the negative correlation between memory load modulation of alpha power and WMC was no longer statistically significant but still somewhat detectable. These results suggest that (1) individuals with low WMC demonstrate stronger alpha power modulation by memory load, reflecting possibly an increased reliance on sensory gating to suppress task-irrelevant information in these individuals, in contrast to their high WMC counterparts who rely more on frontal areas to perform this function and (2) this negative association between memory load modulation of alpha oscillations and WMC is vulnerable to drug-related cognitive disruption.


2019 ◽  
Author(s):  
Nicole Hakim ◽  
Tobias Feldmann-Wüstefeld ◽  
Edward Awh ◽  
Edward K. Vogel

AbstractWorking memory maintains information so that it can be used in complex cognitive tasks. A key challenge for this system is to maintain relevant information in the face of task-irrelevant perturbations. In this series of experiments, we investigated the impact of task-irrelevant interruptions on neural representations of working memory. We recorded electroencephalogram (EEG) activity in humans while they performed a working memory task. On a subset of trials, we interrupted participants with salient, but task-irrelevant objects. To track the impact of these task-irrelevant interruptions on neural representations of working memory, we measured two well-characterized, temporally sensitive EEG markers that reflect active, prioritized working memory representations: the contralateral delay activity (CDA) and lateralized alpha power (8-12hz). Following interruption, we found that CDA momentarily sustained, but was gone by the end of the trial. Lateralized alpha power was immediately influenced by the interrupters, but recovered by the end of the trial. This suggests that dissociable neural processes contribute to the maintenance of working memory information. Additionally, we found that task expectancy modulated the timing and magnitude of how these two neural signals responded to task-irrelevant interruptions, suggesting that the brain’s response to task-irrelevant interruption is shaped by task context. The distinct time courses of and influence of task context on these two neural signatures of working memory have many interesting theoretical implications about how information is actively maintained in working memory.Significance statementWorking memory plays a central role in intelligent behaviors because it actively maintains relevant information that is easily accessible and manipulatable. In everyday life, we are often interrupted while performing such complex cognitive tasks. Therefore, understanding how working memory responds to and overcomes momentary task-irrelevant interruptions is critical for us to understand how complex cognition works. Here, we unveil how two distinct neural signatures of working memory respond to task-irrelevant interruptions by recording electroencephalogram activity in humans. Our findings raise long-standing theoretical questions about how different neural and cognitive processes contribute to the maintenance of information in working memory.


2020 ◽  
Author(s):  
Sabrina Sghirripa ◽  
Lynton Graetz ◽  
Ashley Merkin ◽  
Nigel C Rogasch ◽  
Michael C Ridding ◽  
...  

Author(s):  
Stefan Berti ◽  
Urte Roeber ◽  
Erich Schröger

Abstract. The present study investigates bottom-up effects serving the optimal balance between focusing attention on relevant information and distractibility by potentially significant events outside the focus of attention. We tested whether distraction, indicated by behavioral and event-related brain potential (ERP) measures, varies with the strength of task-irrelevant deviances. Twenty subjects performed a tone-duration discrimination task (200 or 400 ms sinusoidal tones presented equiprobably). The stimuli were presented with frequent standard (p = 0.84; 1000 Hz) or infrequent deviant (p = 0.16) pitch. These task-irrelevant pitch changes consisted in a frequency increase/decrease of 1%, 3%, 5%, or 10%. Each of them resulted in prolonged reaction times (RT) in the duration discrimination task and elicited the MMN, P3a, and RON components of the ERP. Importantly, these measures did increase as a function of pitch deviance. Separating the individual trials on the 1% deviation level into trials with and without RT prolongation, i.e., behavioral distraction effect, revealed that both subgroups had similar MMN, but P3a and RON were confined to the trials with RT prolongation. Results are interpreted within a model relating preattentive deviance detection, distraction, and working memory.


Author(s):  
Thomas Jacobsen ◽  
Erich Schröger

Abstract. Working memory uses central sound representations as an informational basis. The central sound representation is the temporally and feature-integrated mental representation that corresponds to phenomenal perception. It is used in (higher-order) mental operations and stored in long-term memory. In the bottom-up processing path, the central sound representation can be probed at the level of auditory sensory memory with the mismatch negativity (MMN) of the event-related potential. The present paper reviews a newly developed MMN paradigm to tap into the processing of speech sound representations. Preattentive vowel categorization based on F1-F2 formant information occurs in speech sounds and complex tones even under conditions of high variability of the auditory input. However, an additional experiment demonstrated the limits of the preattentive categorization of language-relevant information. It tested whether the system categorizes complex tones containing the F1 and F2 formant components of the vowel /a/ differently than six sounds with nonlanguage-like F1-F2 combinations. From the absence of an MMN in this experiment, it is concluded that no adequate vowel representation was constructed. This shows limitations of the capability of preattentive vowel categorization.


2015 ◽  
Vol 6 (1) ◽  
pp. 16 ◽  
Author(s):  
Anne-Laure Oftinger ◽  
Valerie Camos

<p>Previous research in adults has indicated two maintenance mechanisms of verbal information in working memory, i.e., articulatory rehearsal and attentional refreshing. However, only three studies have examined their joint contribution to children’s verbal working memory. The present study aimed at extending this line of research by investigating the developmental changes occurring from 6 to 9 years old. In two experiments using complex span tasks, children of three different age groups maintained letters or words while performing a concurrent task. The opportunity for attentional refreshing was manipulated by varying the attentional demand of the concurrent task. Moreover, this task was performed either silently by pressing keys or aloud, the latter inducing a concurrent articulation. As expected, recall performance increased strongly with age. More interestingly, concurrent articulation had a detrimental effect on recall even in 6-year-old children. Similarly, introducing a concurrent attention-demanding task impaired recall performance at all ages. Finally, the effect of the availability of rehearsal and of attentional refreshing never interacted at any age. This suggested an independence of the two mechanisms in the maintenance of verbal information in children’s working memory. Implications for the development of rehearsal use and for the role of attention in working memory are discussed.</p>


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