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.

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.

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

scholarly journals Visual and verbal working memory loads interfere with scene viewing

2019 ◽  
Author(s):  
Deborah Cronin ◽  
Candace Elise Peacock ◽  
John M. Henderson
Keyword(s):  
Working Memory ◽  
Eye Movements ◽  
Visual Working Memory ◽  
Verbal Memory ◽  
Visual Memory ◽  
Memory Load ◽  
Memory Task ◽  
Verbal Working Memory ◽  
Working Memory Load ◽  
Scene Viewing

Working memory is thought to be divided into distinct visual and verbal subsystems. Studies of visual working memory frequently use verbal working memory tasks as control conditions and/or use articulatory suppression to ensure visual load remains in visual memory. Using these verbal tasks relies on the assumption that the verbal working memory load will not interfere with the same processes as visual working memory. In the present study, participants maintained a visual or verbal working memory load while simultaneously viewing scenes. Because eye movements and visual working memory are closely linked, we anticipated the visual load would interfere with scene viewing (and vice versa), while the verbal load would not. Surprisingly, both visual and verbal memory loads interfered with scene viewing behavior, while scene viewing did not significantly interfere with performance on either memory task. These results suggest that a verbal working memory load can interfere with a visual task and contribute to the growing literature suggesting the visual and verbal subsystems of working memory are less distinct than previously thought. Our data also stands at odds with previous work suggesting that visual working memory is obligatorily recruited by saccadic eye movements.

scholarly journals Serial Position Effects in Auditory Event-related Potentials during Working Memory Retrieval

2004 ◽  
Vol 16 (1) ◽  
pp. 40-52 ◽  
Author(s):  
Edward J. Golob ◽  
Arnold Starr
Keyword(s):  
Working Memory ◽  
Serial Position ◽  
Memory Retrieval ◽  
Memory Load ◽  
Memory Task ◽  
Event Related Potentials ◽  
Control Task ◽  
Position Effects ◽  
Serial Position Effects ◽  
Related Potentials

It is established that recall of an item from a list of sequentially presented items is sensitive to the item's position in the memorized list. However, little is known about the brain mechanisms that mediate these serial position effects. Studies of working memory retrieval using event-related potentials report amplitude reductions during retrieval (auditory cortical N100, neocortical late positive wave [LPW]) as memory load increases. We tested the hypothesis that N100 and LPW amplitudes to probes are also affected by serial position. Eventrelated potentials were recorded from subjects performing an auditory working memory task. A set of one or five digits was memorized, then subjects classified a probe digit as either present or absent from the memory set. A control task was also given. Amplitudes of the N100 and LPW were reduced in the 5-item versus the 1-item set. In the 5-item set N100 amplitude was significantly larger for the initial (1st) serial position, relative to Positions 2–5, while linear increases in LPW amplitude were seen across serial positions (5th > 1st position). A control task without memorization showed no N100 or LPW amplitude changes with set size or serial position. The findings reveal that the N100 and LPW are influenced differently by serial position during working memory retrieval: N100 shows a primacy effect and LPW demonstrates a recency effect. The results suggest that primacy and recency effects may be mediated by different brain regions at different times during memory retrieval.

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 Are visual working memory and episodic memory distinct processes? Insight from stroke patients by lesion-symptom mapping

2021 ◽  
Author(s):  
Selma Lugtmeijer ◽  
◽  
Linda Geerligs ◽  
Frank Erik de Leeuw ◽  
Edward H. F. de Haan ◽  
...  
Keyword(s):  
Working Memory ◽  
Episodic Memory ◽  
Visual Working Memory ◽  
Visual Memory ◽  
Right Hemisphere ◽  
Memory Task ◽  
Stroke Patients ◽  
Lesion Symptom Mapping ◽  
Criterion Setting ◽  
The Right

AbstractWorking memory and episodic memory are two different processes, although the nature of their interrelationship is debated. As these processes are predominantly studied in isolation, it is unclear whether they crucially rely on different neural substrates. To obtain more insight in this, 81 adults with sub-acute ischemic stroke and 29 elderly controls were assessed on a visual working memory task, followed by a surprise subsequent memory test for the same stimuli. Multivariate, atlas- and track-based lesion-symptom mapping (LSM) analyses were performed to identify anatomical correlates of visual memory. Behavioral results gave moderate evidence for independence between discriminability in working memory and subsequent memory, and strong evidence for a correlation in response bias on the two tasks in stroke patients. LSM analyses suggested there might be independent regions associated with working memory and episodic memory. Lesions in the right arcuate fasciculus were more strongly associated with discriminability in working memory than in subsequent memory, while lesions in the frontal operculum in the right hemisphere were more strongly associated with criterion setting in subsequent memory. These findings support the view that some processes involved in working memory and episodic memory rely on separate mechanisms, while acknowledging that there might also be shared processes.

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