scholarly journals Interhemispheric Connectivity Supports Load-Dependent Working Memory Maintenance for Complex Visual Stimuli

2021 ◽  
Author(s):  
Chelsea Reichert Plaska ◽  
Jefferson Ortega ◽  
Bernard A. Gomes ◽  
Timothy M. Ellmore
Keyword(s):  
Working Memory ◽  
Phase Locking ◽  
Visual Stimuli ◽  
Load Condition ◽  
Brain Regions ◽  
Delay Period ◽  
Temporal Region ◽  
Verbal Rehearsal ◽  
Complex Stimuli ◽  
Low Load

AbstractAn open question in the working memory (WM) field is how information is kept online during the WM delay period. Maintenance of simple stimuli in WM is supported by connectivity between frontal and parietal brain regions. How does delay period activity and connectivity support WM of complex stimuli? Twenty-two participants completed a modified Sternberg WM task with complex stimuli and were told to remember either 2 (low-load) or 5 (high-load) scenes while 32- channel scalp EEG was recorded. During the 6-sec delay period 6 phase-scrambled scenes were presented, which served as interference. While increasing the WM load, particularly with complex stimuli, places a greater demand on attentional resources, interfering stimuli may hijack the available resources. This was confirmed in the examination of theta and alpha amplitude, as amplitude was reduced for the high WM load as compared with the low WM load across frontal, central, and parietal regions. Delay period connectivity was assessed with phase-locking value (PLV). We identified 3 supporting networks that facilitated performance for the low-load condition: 1) increased PLV between left frontal and right posterior temporal in the theta and alpha bands; 2) increased PLV between right anterior temporal and left central in the alpha and lower beta bands; and 3) increased PLV between left anterior temporal and left posterior temporal in theta, alpha, and lower beta bands for the low-load condition. These results suggest that these brain networks facilitated the low-load WM by filtering of interference and the use of verbal rehearsal during the delay period.Impact StatementAlthough, studies of working memory maintenance with simple stimuli have suggested a role of frontal-parietal networks in supporting maintenance, the current study suggests that maintenance of complex visual stimuli with interference present is supported by interhemispheric frontal-posterior temporal and intrahemispheric left temporal region connectivity. These networks support maintenance by filtering of the interfering stimuli, which facilitates the use of verbal rehearsal strategies during the delay period.

scholarly journals Finger representations in primary somatosensory cortex are modulated during vibrotactile working memory

2021 ◽  
Author(s):  
Finn Rabe ◽  
Sanne Kikkert ◽  
Nicole Wenderoth
Keyword(s):  
Working Memory ◽  
Somatosensory Cortex ◽  
Pattern Analysis ◽  
Blood Oxygen Level Dependent ◽  
Brain Regions ◽  
Delay Period ◽  
Blood Oxygen Level ◽  
Secondary Somatosensory Cortex ◽  
Analysis Technique ◽  
Hand Area

It is well-established that vibrotactile stimulations elicit Blood-oxygen-level-dependent (BOLD) responses in somatotopically organized brain regions. Whether these somatotopic maps are modulated by working memory (WM) is still unknown. In our WM experiment, participants had to compare frequencies that were separated by a delay period. Vibrotactile stimuli were sequentially applied to either their right index or little finger. Using functional MRI, we investigated whether vibrotactile WM modulated neural activity in primary somatosensory (S1), an area that is known to contain individual finger representations. Our mass-univariate results revealed the well-described network of brain regions involved in WM. Interestingly, our mass-univariate results did not demonstrate S1 to be part of this network. However, when we parametrically modulated the time-binned regressors in our GLM we found that the delay activity in S1 and secondary somatosensory cortex (S2) was reflected in a U-shaped manner. Using multi-voxel pattern analysis (MVPA), an analysis technique that is more sensitive to subtle activity differences, we found finger-specific patterns of activation in the S1 hand area during the WM delay period. These results indicate that processes underlying WM modulate finger-specific representations during our discrimination task.

scholarly journals Behavioral prioritization enhances working memory precision and neural population gain

2021 ◽  
Author(s):  
Aspen H. Yoo ◽  
Alfredo Bolaños ◽  
Grace E. Hallenbeck ◽  
Masih Rahmati ◽  
Thomas C. Sprague ◽  
...  
Keyword(s):  
Working Memory ◽  
Brain Area ◽  
Brain Regions ◽  
Delay Period ◽  
Common Finding ◽  
Neural Population ◽  
Association Cortex ◽  
Absolute Amount ◽  
Neural Populations ◽  
Memory Precision

ABSTRACTHumans allocate visual working memory (WM) resource according to behavioral relevance, resulting in more precise memories for more important items. Theoretically, items may be maintained by feature-tuned neural populations, where the relative gain of the populations encoding each item determines precision. To test this hypothesis, we compared the amplitudes of delay-period activity in the different parts of retinotopic maps representing each of several WM items, predicting amplitude would track with behavioral priority. Using fMRI, we scanned participants while they remembered the location of multiple items over a WM delay, then reported the location of one probed item using a memory-guided saccade. Importantly, items were not equally probable to be probed (0.6, 0.3, 0.1, 0.0), which was indicated with a pre-cue. We analyzed fMRI activity in ten visual field maps in occipital, parietal, and frontal cortex known to be important for visual WM. In early visual cortex, but not association cortex, the amplitude of BOLD activation within voxels corresponding to the retinotopic location of visual WM items increased with the priority of the item. Interestingly, these results were contrasted with a common finding that higher-level brain regions had greater delay-period activity, demonstrating a dissociation between the absolute amount of activity in a brain area, and the activity of different spatially-selective populations within it. These results suggest that the distribution of WM resources according to priority sculpts the relative gains of neural populations that encode items, offering a neural mechanism for how prioritization impacts memory precision.

scholarly journals Behavioral Prioritization Enhances Working Memory Precision and Neural Population Gain

2021 ◽  
pp. 1-14
Author(s):  
Aspen H. Yoo ◽  
Alfredo Bolaños ◽  
Grace E. Hallenbeck ◽  
Masih Rahmati ◽  
Thomas C. Sprague ◽  
...  
Keyword(s):  
Working Memory ◽  
Brain Area ◽  
Brain Regions ◽  
Delay Period ◽  
Common Finding ◽  
Neural Population ◽  
Association Cortex ◽  
Absolute Amount ◽  
Neural Populations ◽  
Memory Precision

Abstract Humans allocate visual working memory (WM) resource according to behavioral relevance, resulting in more precise memories for more important items. Theoretically, items may be maintained by feature-tuned neural populations, where the relative gain of the populations encoding each item determines precision. To test this hypothesis, we compared the amplitudes of delay period activity in the different parts of retinotopic maps representing each of several WM items, predicting the amplitudes would track behavioral priority. Using fMRI, we scanned participants while they remembered the location of multiple items over a WM delay and then reported the location of one probed item using a memory-guided saccade. Importantly, items were not equally probable to be probed (0.6, 0.3, 0.1, 0.0), which was indicated with a precue. We analyzed fMRI activity in 10 visual field maps in occipital, parietal, and frontal cortex known to be important for visual WM. In early visual cortex, but not association cortex, the amplitude of BOLD activation within voxels corresponding to the retinotopic location of visual WM items increased with the priority of the item. Interestingly, these results were contrasted with a common finding that higher-level brain regions had greater delay period activity, demonstrating a dissociation between the absolute amount of activity in a brain area and the activity of different spatially selective populations within it. These results suggest that the distribution of WM resources according to priority sculpts the relative gains of neural populations that encode items, offering a neural mechanism for how prioritization impacts memory precision.

scholarly journals EXPRESS: Do cognitive load and ADHD traits affect the tendency to prioritise social information in scenes?

2021 ◽  
pp. 174702182110664
Author(s):  
Astrid Priscilla Martinez-Cedillo ◽  
Kevin Dent ◽  
Tom Foulsham
Keyword(s):  
Memory Load ◽  
Flanker Task ◽  
Load Condition ◽  
Object A ◽  
Social Object ◽  
Complex Stimuli ◽  
The Social ◽  
Complex Scenes ◽  
Low Load ◽  
Social Area

We report two experiments investigating the effect of working memory (WM) load on selective attention. Experiment 1 was a modified version of Lavie et al. (2004) and confirmed that increasing memory load disrupted performance in the classic flanker task. Experiment 2 used the same manipulation of WM load to probe attention during the viewing of complex scenes, while also investigating individual differences in ADHD traits. In the image viewing task, we measured the degree to which fixations targeted each of two crucial objects: (1) a social object (a person in the scene) and (2) a non-social object of higher or lower physical salience. We compared the extent to which increasing WM load would change the pattern of viewing of the physically salient and socially salient objects. If attending to the social item requires greater default voluntary top-down resources, then the viewing of social objects should show stronger modulation by WM load compared to viewing of physically salient objects. The results showed that the social object was fixated to a greater degree than the other object (regardless of physical saliency). Increased saliency drew fixations away from the background leading to slightly increased fixations on the non-social object, without changing fixations on the social object. Increased levels of ADHD-like traits were associated with fewer fixations on the social object, but only in the high salient, low load condition. Importantly, WM load did not affect number of fixations on the social object. Such findings suggest rather surprisingly that attending to a social area in complex stimuli is not dependent on the availability of voluntary topdown resources.

scholarly journals Working memory performance is tied to stimulus complexity

2021 ◽  
Author(s):  
Roland Pusch ◽  
Julian Packheiser ◽  
Amir Hossein Azizi ◽  
Celil Semih Sevincik ◽  
Jonas Rose ◽  
...  
Keyword(s):  
Working Memory ◽  
Visual Information ◽  
Neural Coding ◽  
Single Unit ◽  
Memory Performance ◽  
Delay Period ◽  
Memory Representation ◽  
Stimulus Complexity ◽  
Behavioral Experiments ◽  
Complex Stimuli

1.SummaryWorking memory is the cognitive capability to maintain and process information over short periods. Recent behavioral and computational studies have shown that increased visual information of the presented stimulus material is associated with enhanced working memory performance. However, the underlying neural correlates of this association are unknown. To identify how stimuli of different visual information levels affect working memory performance, we conducted behavioral experiments and single unit recordings in the avian analog of the prefrontal cortex, the nidopallium caudolaterale (NCL). On the behavioral level, we confirmed that feature-rich complex stimuli demonstrated higher working memory performance compared to feature-poor simple stimuli. This difference was reflected by distinct neural coding patterns at the single unit level. For complex stimuli, we found a highly multiplexed neuronal code. During the sample presentation, NCL neurons initially reflected both visual and value-related features of the presented stimuli that switched to a representation of the upcoming choice during a delay period. When processing simple stimuli, NCL neurons did not multiplex and represented the upcoming choice already during stimulus presentation and throughout the delay period. It is conceivable that the maintenance of the upcoming choice in working memory was prolonged for simple stimuli due to the early choice representation. This possibly resulted in increased decay of the working memory trace ultimately leading to a decrease in performance. In conclusion, we found that increases in stimulus complexity are associated with increased neuronal multiplexing of the working memory representation. This could possibly allow for a facilitated read-out of the neural code resulting in further enhancements of working memory performance.

scholarly journals Oscillatory correlates of auditory working memory examined with human electrocorticography

2020 ◽  
Author(s):  
Sukhbinder Kumar ◽  
Phillip E. Gander ◽  
Joel I. Berger ◽  
Alexander J. Billig ◽  
Kirill V. Nourski ◽  
...  
Keyword(s):  
Working Memory ◽  
Auditory Cortex ◽  
Frontal Cortex ◽  
Low Frequency ◽  
Brain Regions ◽  
Delay Period ◽  
Blood Oxygenation ◽  
Oscillatory Activity ◽  
Frequency Bands ◽  
Inferior Frontal Cortex

AbstractThis work examines how sounds are held in auditory working memory (AWM) in humans by examining oscillatory local field potentials (LFPs) in candidate brain regions. Previous fMRI studies by our group demonstrated blood oxygenation level-dependent (BOLD) response increases during maintenance in auditory cortex, inferior frontal cortex and the hippocampus using a paradigm with a delay period greater than 10s. The relationship between such BOLD changes and ensemble activity in different frequency bands is complex, and the long delay period raised the possibility that long-term memory mechanisms were engaged. Here we assessed LFPs in different frequency bands in six subjects with recordings from all candidate brain regions using a paradigm with a short delay period of 3 s. Sustained delay activity was demonstrated in all areas, with different patterns in the different areas. Enhancement in low frequency (delta) power and suppression across higher frequencies (beta/gamma) were demonstrated in primary auditory cortex in medial Heschl’s gyrus (HG) whilst non-primary cortex showed patterns of enhancement and suppression that altered at different levels of the auditory hierarchy from lateral HG to superior- and middle-temporal gyrus. Inferior frontal cortex showed increasing suppression with increasing frequency. The hippocampus and parahippocampal gyrus showed low frequency increases and high frequency decreases in oscillatory activity. The work demonstrates sustained activity patterns that can only be explained by AWM maintenance, with prominent low-frequency increases in medial temporal lobe regions.

scholarly journals Interactions of explicit and implicit learning mechanisms in cross-situational word learning

2020 ◽  
Author(s):  
Tanja Roembke ◽  
Bob McMurray
Keyword(s):  
Working Memory ◽  
Implicit Learning ◽  
Word Learning ◽  
Memory Task ◽  
Load Condition ◽  
High Load ◽  
Learning Processes ◽  
Learning Mechanisms ◽  
Low Load ◽  
Memory Resources

Both explicit and implicit learning processes contribute to cross-situational word learning (e.g., Roembke & McMurray, 2016; Warren et al., 2019). However, it is unclear how these learning processes interact, and if any specific aspect of cross-situational word learning is purely explicit. To investigate this, participants completed cross-situational word learning trials as well as a memory task that required remembering five (high-load) or only one (low-load) number in a between-subject, dual-task paradigm. This allowed us to manipulate whether working memory resources were available for explicit processing or not. Further, we used trial-by-trial analyses to estimate how different learning effects that are thought to map onto either explicit or implicit learning processes are affected by condition. Word learning accuracy was lower in the high-load than in the low-load condition; this was likely driven by performance late in the experiment. Moreover, both the more explicit and implicit effects were reduced when limiting working memory resources, suggesting that neither is purely the result of or independent of explicit learning processes. Consistent with a hybrid account, these findings indicate that explicit and implicit learning processes do not compete, but rather support each other, during cross-situational word learning.

Attentional Load Effects on Emotional Content in Face Working Memory

2021 ◽  
Author(s):  
Lívia Valenti ◽  
Isabella Wada Pucci ◽  
Ricardo Basso Garcia ◽  
Margaret Jackson ◽  
Cesar Alexis Galera
Keyword(s):  
Working Memory ◽  
Load Condition ◽  
High Load ◽  
Emotional Faces ◽  
Attentional Resources ◽  
Attentional Load ◽  
Low Load ◽  
Test Face ◽  
Load Effects ◽  
Face Working Memory

This study investigated the role of attentional resources in processing emotional faces on working memory (WM). Participants memorised two face arrays with the same emotion but different identities and were required to judge whether the test face had the same identity as one of the previous faces. Concurrently during encoding and maintenance, a sequence of high-or-low pitched tones (high load) or white noise bursts (low load) was presented, and participants were required to count how many low-tones were heard. Experiment 1 and 2 used an emotional and neutral test face, respectively. The results revealed a significant WM impairment for sad and angry faces in the high load vs low load condition but not for happy faces. Happy faces were better recognised than other emotional faces in a high load. In Experiment 1, participants remembered better happy faces than other emotional faces. In contrast, Experiment 2 showed that performance was poorer for happy than sad faces but not for angry faces. This evidence suggests that depleting of attentional resources affects less WM for happy faces than other emotional faces, but also differential effects on WM for emotional faces depend on the presence or absence of emotion face at retrieval.

scholarly journals Experiential and Strategic Emotional Intelligence Are Implicated When Inhibiting Affective and Non-Affective Distractors: Findings from Three Emotional Flanker N-Back Tasks

2021 ◽  
Vol 9 (1) ◽  
pp. 12
Author(s):  
Ming D. Lim ◽  
Damian P. Birney
Keyword(s):  
Working Memory ◽  
Emotional Intelligence ◽  
Experimental Evidence ◽  
Cognitive Processes ◽  
Response Times ◽  
Memory Task ◽  
Low Load ◽  
Affective Information ◽  
Accuracy Rates

Emotional intelligence (EI) refers to a set of competencies to process, understand, and reason with affective information. Recent studies suggest ability measures of experiential and strategic EI differentially predict performance on non-emotional and emotionally laden tasks. To explore cognitive processes underlying these abilities further, we varied the affective context of a traditional letter-based n-back working-memory task. In study 1, participants completed 0-, 2-, and 3-back tasks with flanking distractors that were either emotional (fearful or happy faces) or non-emotional (shapes or letters stimuli). Strategic EI, but not experiential EI, significantly influenced participants’ accuracy across all n-back levels, irrespective of flanker type. In Study 2, participants completed 1-, 2-, and 3-back levels. Experiential EI was positively associated with response times for emotional flankers at the 1-back level but not other levels or flanker types, suggesting those higher in experiential EI reacted slower on low-load trials with affective context. In Study 3, flankers were asynchronously presented either 300 ms or 1000 ms before probes. Results mirrored Study 1 for accuracy rates and Study 2 for response times. Our findings (a) provide experimental evidence for the distinctness of experiential and strategic EI and (b) suggest that each are related to different aspects of cognitive processes underlying working memory.

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