F187. Pre-Stimulus Alpha Power and Contralateral Delay Activity During Visual Working Memory in First Episode Schizophrenia

2019 ◽  
Vol 85 (10) ◽  
pp. S285-S286
Author(s):  
Brian Coffman ◽  
Tim Murphy ◽  
Gretchen Haas ◽  
Carl Olson ◽  
Raymond Y. Cho ◽  
...  
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
First Episode ◽  
Alpha Power ◽  
Contralateral Delay Activity ◽  
First Episode Schizophrenia

scholarly journals Stimuli may have little impact on the deficit of visual working memory accuracy in first-episode schizophrenia

2019 ◽  
Vol Volume 15 ◽  
pp. 481-489 ◽  
Author(s):  
Shenglin She ◽  
Bei Zhang ◽  
Lin Mi ◽  
Haijing Li ◽  
Qijie Kuang ◽  
...  
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
First Episode ◽  
Memory Accuracy ◽  
First Episode Schizophrenia

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.

A direct neural measure of variable precision representations in visual working memory

2021 ◽  
Author(s):  
Christian Merkel ◽  
Mandy Viktoria Bartsch ◽  
Mircea A Schoenfeld ◽  
Anne-Katrin Vellage ◽  
Notger G Müller ◽  
...  
Keyword(s):  
Working Memory ◽  
Visual Working Memory ◽  
Recall Performance ◽  
Human Subjects ◽  
Item Information ◽  
Estimation Task ◽  
Active Representation ◽  
Contralateral Delay Activity ◽  
Memory Representations ◽  
Precision Estimation

Visual working memory (VWM) is an active representation enabling the manipulation of item information even in the absence of visual input. A common way to investigate VWM is to analyze the performance at later recall. This approach, however, leaves uncertainties about whether the variation of recall performance is attributable to item encoding and maintenance or to the testing of memorized information. Here, we record the contralateral delay activity (CDA) - an established electrophysiological measure of item storage and maintenance - in human subjects performing a delayed orientation precision estimation task. This allows us to link the fluctuation of recall precision directly to the process of item encoding and maintenance. We show that for two sequentially encoded orientation items, the CDA amplitude reflects the precision of orientation recall of both items, with higher precision being associated with a larger amplitude. Furthermore, we show that the CDA amplitude for each item varies independently from each other, suggesting that the precision of memory representations fluctuates independently.

scholarly journals Cognitive heterogeneity in first-episode schizophrenia

2005 ◽  
Vol 187 (6) ◽  
pp. 516-522 ◽  
Author(s):  
Eileen M. Joyce ◽  
Sam B. Hutton ◽  
Stanley H. Mutsatsa ◽  
Thomas R. E. Barnes
Keyword(s):  
Working Memory ◽  
Cognitive Decline ◽  
Spatial Working Memory ◽  
Age At Onset ◽  
Chronic Schizophrenia ◽  
First Episode ◽  
Entire Group ◽  
Illness Onset ◽  
Cognitive Heterogeneity ◽  
First Episode Schizophrenia

BackgroundStudies of chronic schizophrenia suggest that there are subgroups with different profiles of cognitive impairment.AimsTo determine whether such heterogeneity is present at illness onset and any relationship to clinical variables.MethodNinety-three community patients with first-episode schizophrenia and 50 healthy volunteers were assessed for premorbid (Revised National Adult Reading Test) and current IQ, memory and executive function.ResultsHalf of those with schizophrenia had preserved IQ in the normal range but there was evidence of a specific impairment in spatial working memory even in those with high/average IQ; 37 out of 93 (40%) had generalised cognitive decline. Those with low premorbid IQ were significantly younger at illness onset. For the entire group, age at onset correlated positively with premorbid but not current IQ.ConclusionsAt illness onset, cognitive heterogeneity is present in people with schizophrenia, with a high proportion having undergone general cognitive decline. However, working memory impairment may be a common feature. Lower premorbid IQ is a risk factor for an earlier onset.

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.

Small-world networks in individuals at ultra-high risk for psychosis and first-episode schizophrenia during a working memory task

2013 ◽  
Vol 535 ◽  
pp. 35-39 ◽  
Author(s):  
Kyungun Jhung ◽  
Sung-Hwan Cho ◽  
Ji-Hyun Jang ◽  
Jin Young Park ◽  
Dongkwan Shin ◽  
...  
Keyword(s):  
Working Memory ◽  
High Risk ◽  
Memory Task ◽  
Small World ◽  
First Episode ◽  
Small World Networks ◽  
Ultra High Risk ◽  
First Episode Schizophrenia

scholarly journals Perturbing Neural Representations of Working Memory with Task-irrelevant Interruption

2020 ◽  
Vol 32 (3) ◽  
pp. 558-569 ◽  
Author(s):  
Nicole Hakim ◽  
Tobias Feldmann-Wüstefeld ◽  
Edward Awh ◽  
Edward K. Vogel
Keyword(s):  
Working Memory ◽  
Memory Task ◽  
Relevant Information ◽  
Alpha Power ◽  
Neural Signals ◽  
Neural Representations ◽  
Contralateral Delay Activity ◽  
The Face ◽  
Task Irrelevant ◽  
The Impact

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.

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