Multiple Levels of Stimulus Representation in Visual Working Memory

2006 ◽  
Vol 18 (5) ◽  
pp. 844-858 ◽  
Author(s):  
Eunsam Shin ◽  
Monica Fabiani ◽  
Gabriele Gratton
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
Visual Memory ◽  
Memory Search ◽  
Event Related Potentials ◽  
Neural Representation ◽  
Set Size ◽  
Related Potentials ◽  
Multiple Levels ◽  
Letter Case

Object recognition presumably involves activation of multiple levels of representation. Here we use the encoding-related lateralization (ERL) method [Gratton, G. The contralateral organization of visual memory: A theoretical concept and a research tool. Psychophysiology, 35, 638–647, 1998] to describe the sequential activation of several of these levels. The ERL uses divided-field encoding to generate contralaterally biased representations in the brain. The presence and nature of these representations can be demonstrated by examining the event-related potentials (ERPs) elicited by centrally presented test probes for lateralized activity corresponding to the encoding side. We recorded ERPs during a memory-search task. Memory sets were composed of two or four uppercase letters displayed half to the left and half to the right of fixation. Probe stimuli were composed of one letter presented foveally in either upper- or lowercase. Letter case was manipulated to differentiate the time course of physical and symbolic levels of letter representation. Memory set size was manipulated to examine a relational level of letter representation. We found multiple ERLs in response to the probes: (1) An early (peak = 170 msec) case-dependent (but set size independent) ERL, most evident at P7/P8, indexing the availability of a physical level of letter representation; (2) a later (200–400 msec) more diffusedly distributed ERL, independent of both letter case and set size, indexing a symbolic level of letter representation; (3) a long-latency (400–600 msec) ERL occurring at posterior sites, larger for the case match, Set Size 2 condition, indexing competition for neural representation across multiple letters. By assuming that these ERL activities track the progression of letter representation over time, we propose a model of letter processing in the context of visual working memory.

scholarly journals Brain Processing of Complex Geometric Forms in a Visual Memory Task Increases P2 Amplitude

2020 ◽  
Vol 10 (2) ◽  
pp. 114
Author(s):  
Héctor A. Cepeda-Freyre ◽  
Gregorio Garcia-Aguilar ◽  
Jose R. Eguibar ◽  
Carmen Cortes
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
Cognitive Processing ◽  
Visual Memory ◽  
Memory Load ◽  
Memory Task ◽  
Event Related Potentials ◽  
Brain Regions ◽  
Test Phase ◽  
Related Potentials

We study the cognitive processing of visual working memory in three different conditions of memory load and configuration change. Altering this features has been shown to alter the brain’s processing in memory tasks. Most studies dealing with this issue have used the verbal-phonological modality. We use complex geometric polygons to assess visual working memory in a modified change detection task. Three different types of backgrounds were used to manipulate memory loading and 18 complex geometric polygons to manipulate stimuli configuration. The goal of our study was to test whether the memory load and configuration affect the correct-recall ratios. We expected that increasing visual items loading and changing configuration of items would induce differences in working memory performance. Brain activity related to the task was assessed through event-related potentials (ERP), during the test phase of each trial. Our results showed that visual items loading and changing of item configuration affect working memory on test phase on ERP component P2, but does not affect performance. However frontal related ERP component—P3—was minimally affected by visual memory loading or configuration changing, supporting that working memory is related to a filtering processing in posterior brain regions.

Face and Word Recognition in Patients with Left and Right Hemispheric Lesions: Evidence from Reaction Times and ERPs

2002 ◽  
Vol 13 (1) ◽  
pp. 69-83 ◽  
Author(s):  
Stefan R. Schweinberger ◽  
Thomas Klos ◽  
Werner Sommer
Keyword(s):  
Slow Wave ◽  
Reaction Times ◽  
Memory Search ◽  
Event Related Potentials ◽  
Performance Deficits ◽  
Set Size ◽  
Left Brain ◽  
Related Potentials ◽  
Abstract Words ◽  
Left Brain Damage

Abstract: We recorded reaction times (RTs) and event-related potentials (ERPs) in patients with unilateral lesions during a memory search task. Participants memorized faces or abstract words, which were then recognized among new ones. The RT deficit found in patients with left brain damage (LBD) for words increased with memory set size, suggesting that their problem relates to memory search. In contrast, the RT deficit found in patients with RBD for faces was apparently related to perceptual encoding, a conclusion also supported by their reduced P100 ERP component. A late slow wave (720-1720 ms) was enhanced in patients, particularly to words in patients with LBD, and to faces in patients with RBD. Thus, the slow wave was largest in the conditions with most pronounced performance deficits, suggesting that it reflects deficit-related resource recruitment.

scholarly journals Fear not! Anxiety biases attentional enhancement of threat without impairing working memory filtering

2019 ◽  
Author(s):  
Christine Salahub ◽  
Stephen Emrich
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
State Anxiety ◽  
Attentional Control ◽  
Event Related Potentials ◽  
Memory Storage ◽  
Attentional Biases ◽  
Related Potentials ◽  
Filtering Efficiency ◽  
Memory Resources

Individuals with anxiety have attentional biases toward threat-related distractors. This deficit in attentional control has been shown to impact visual working memory (VWM) filtering efficiency, as anxious individuals inappropriately store threatening distractors in VWM. It remains unclear, however, whether this mis-allocation of memory resources is due to inappropriate attentional enhancement of threatening distractors, or to a failure in suppression. Here, we used a systematically lateralized VWM task with fearful and neutral faces to examine event-related potentials related to attentional selection (N2pc), suppression (PD), and working memory maintenance (CDA). We found that state anxiety correlated with attentional enhancement of threat-related distractors, such that more anxious individuals had larger N2pc amplitudes toward fearful distractors than neutral distractors. However, there was no correlation between anxiety and memory storage of fearful distractors (CDA). These findings demonstrate that anxiety biases attention toward fearful distractors, but that this bias does not always guarantee increased memory storage of threat-related distractors.

scholarly journals Object maintenance beyond their visible parts in working memory

2018 ◽  
Vol 119 (1) ◽  
pp. 347-355 ◽  
Author(s):  
Siyi Chen ◽  
Thomas Töllner ◽  
Hermann J. Müller ◽  
Markus Conci
Keyword(s):  
Working Memory ◽  
Change Detection ◽  
Visual Working Memory ◽  
Memory Load ◽  
Mental Image ◽  
Event Related Potentials ◽  
Visual Input ◽  
Related Potentials ◽  
Physically Identical ◽  
Partially Occluded

Completion of a partially occluded object requires that a representation of the whole is constructed based on the information provided by the physically specified parts of the stimulus. Such processes of amodal completion rely on the generation and maintenance of a mental image that renders the completed object in visual working memory (VWM). The present study examined this relationship between VWM storage and processes of object completion. We recorded event-related potentials to track VWM maintenance by means of the contralateral delay activity (CDA) during a change detection task in which composite objects (notched shapes abutting an occluding shape) to be memorized were primed to induce either a globally completed object or a noncompleted, mosaic representation. The results revealed an effect of completion in VWM despite physically identical visual input: change detection was more accurate for completed compared with mosaic representations when observers were required to memorize two objects, and these differences were reduced with four memorized items. At the electrophysiological level, globally completed (vs. mosaic) objects gave rise to a corresponding increase in CDA amplitudes. These results indicate that although incorporating the occluded portions of the presented shapes requires mnemonic resources, the complete object representations thus formed in VWM improve change detection performance by providing a more simple, regular shape. Overall, these findings demonstrate that mechanisms of object completion modulate VWM, with the memory load being determined by the structured representations of the memorized stimuli. NEW & NOTEWORTHY This study shows that completion of partially occluded objects requires visual working memory (VWM) resources. In the experiment reported, we induced observers to memorize a given visual input either as completed or as noncompleted objects. The results revealed both a behavioral performance advantage for completed vs. noncompleted objects despite physically identical input, and an associated modulation of an electrophysiological component that reflects VWM object retention, thus indicating that constructing an integrated object consumes mnemonic resources.

scholarly journals Cognitive-behavioural and electrophysiological evidence of the affective consequences of ignoring stimulus representations in working memory

2018 ◽  
Author(s):  
David De Vito ◽  
Anne E. Ferrey ◽  
Mark J. Fenske ◽  
Naseem Al-Aidroos
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
Visual Stimuli ◽  
Event Related Potentials ◽  
Cognitive Behavioural ◽  
Wide Range ◽  
Effective Selection ◽  
Irrelevant Distractors ◽  
Related Potentials ◽  
Affective Consequences

Ignoring visual stimuli in the external environment leads to decreased liking of those items; a phenomenon attributed to the affective consequences of attentional inhibition. Here we investigated the generality of this ‘distractor devaluation’ phenomenon by asking whether ignoring stimuli represented internally within visual working memory has the same affective consequences. In two experiments we presented participants with two or three visual stimuli and then, after the stimuli were no longer visible, provided an attentional cue indicating which item in memory was the target they would have to later recall, and which were task-irrelevant distractors. Participants subsequently judged how much they liked these stimuli. Previously-ignored distractors were consistently rated less favorably than targets, replicating prior findings of distractor devaluation. To gain converging evidence, in Experiment 2, we also examined the electrophysiological processes associated with devaluation by measuring individual differences in attention (N2pc) and working memory (CDA) event-related potentials following the attention cue. Larger amplitude of an N2pc-like component was associated with greater devaluation, suggesting that individuals displaying more effective selection of memory targets—an act aided by distractor inhibition—displayed greater levels of distractor devaluation. Individuals showing a larger post-cue CDA amplitude (but not pre-cue CDA amplitude) also showed greater distractor devaluation, supporting prior evidence that visual working-memory resources have a functional role in effecting devaluation. Together, these findings demonstrate that ignoring working-memory representations has affective consequences, and add to the growing evidence that the contribution of selective-attention mechanisms to a wide range of human thought and behaviors leads to devaluation.

Event-Related Brain Potentials and Central Executive Function: Further Evidence for Baddeley's Model

2001 ◽  
Vol 15 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Ivan Kiss ◽  
Hannah Pazderka-Robinson ◽  
Darlene Floden
Keyword(s):  
Working Memory ◽  
Event Related Potentials ◽  
Central Executive ◽  
Executive Processes ◽  
Short Term ◽  
Brain Potentials ◽  
Set Size ◽  
Related Potentials ◽  
Memory Contents ◽  
Mental Resources

Baddeley's influential model of working memory postulates a unitary central executive that allocates mental resources to several distinct short-term buffers. Subjects viewed individually presented single numerals and were required to maintain memory sets comprised of the most recently represented three stimuli. A clearly discernible visual event-related potentials (ERP) component emerged once the lengths of series of individual numbers exceeded memory set size and revision of working memory contents was required. An ERP correlate of working memory revision also emerged upon updating of auditory stimuli. This component was absent when subjects were exposed to the same series of stimuli in a standard “oddball” target detection situation. ERPs elicited when subjects were given the opportunity to rehearse without the need to update working memory contents clearly differed in latency from ERPs seen during updating. These findings provide support for previous studies suggesting a specific ERP correlate of central executive processes in working memory and are consistent with Baddeley's model.

scholarly journals Distinct neural mechanisms for spatially lateralized and spatially global visual working memory representations

2016 ◽  
Vol 116 (4) ◽  
pp. 1715-1727 ◽  
Author(s):  
Keisuke Fukuda ◽  
Min-Suk Kang ◽  
Geoffrey F. Woodman
Keyword(s):  
Working Memory ◽  
Visual Cortex ◽  
Visual Working Memory ◽  
Imaging Techniques ◽  
Event Related Potentials ◽  
Neural Mechanisms ◽  
Electrophysiological Studies ◽  
Related Potentials ◽  
Memory Representations ◽  
Α Band

Visual working memory (VWM) allows humans to actively maintain a limited amount of information. Whereas previous electrophysiological studies have found that lateralized event-related potentials (ERPs) track the maintenance of information in VWM, recent imaging experiments have shown that spatially global representations can be read out using the activity across the visual cortex. The goal of the present study was to determine whether both lateralized and spatially global electrophysiological signatures coexist. We first show that it is possible to simultaneously measure lateralized ERPs that track the number of items held in VWM from one visual hemfield and parietooccipital α (8–12 Hz) power over both hemispheres indexing spatially global VWM representations. Next, we replicated our findings and went on to show that this bilateral parietooccipital α power as well as the contralaterally biased ERP correlate of VWM carries a signal that can be used to decode the identity of the representations stored in VWM. Our findings not only unify observations across electrophysiology and imaging techniques but also suggest that ERPs and α-band oscillations index different neural mechanisms that map on to lateralized and spatially global representations, respectively.

Event-related potentials (ERP) during a visual working memory task in first episode and chronic schizophrenia

1997 ◽  
Vol 24 (1-2) ◽  
pp. 239
Author(s):  
Daniel Umbricht ◽  
Daniel Javitt ◽  
John Bates ◽  
Simcha Pollak ◽  
Jeffrey Lieberman ◽  
...  
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
Memory Task ◽  
Event Related Potentials ◽  
Chronic Schizophrenia ◽  
First Episode ◽  
Related Potentials
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