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The present study aimed to explore the effect of intermittent theta-burst stimulation (iTBS) on visual working memory for people suffering from methamphetamine use disorder (MUD). Five sessions of iTBS were carried over the left dorsolateral prefrontal cortex (DLPFC) or the vertex as a sham control, with each session in one day. Orientation free-recall tasks were conducted before the iTBS stimulation, after the first and fifth sessions of stimulation. Results showed that when compared with the sham group, a single session of iTBS over the left DLPFC improved participants' working memory performance. Specifically, iTBS over the left DLPFC increased the working memory capacity and such effects enlarged with multiple sessions. The present finding suggested that iTBS over DLPFC could be a promising intervention method to enhance the cognitive function of addicts with MUD. [ABSTRACT FROM AUTHOR]

In contrast to background white noise, the detrimental effects of background speech on verbal working memory (WM) were often explained by speech interference in the same verbal modality. Yet, those results were confounded with potential differences between arousal levels induced by speech and white noise. To address the role of arousal, in the present study, we minimized the verbal interference by using a visual WM task to test the influence of background speech or white noise. Electrodermal activity (EDA) was recorded simultaneously to indicate participants' arousal levels. Results showed that both background speech and white noise significantly improved visual WM performance, which further correlated with individuals' changes of EDA signals. Taken together, our results suggest that background sounds of both speech and white noise facilitate visual WM by raising the arousal level. [ABSTRACT FROM AUTHOR]

The prospects of gaining reward and avoiding punishment widely influence human behavior. Despite of numerous attempts to investigate the influence of motivational signals on working memory (WM), whether the valence and the magnitude of motivational signals interactively influence WM performance remains unclear. To investigate this, the present study used a free‐recall working memory task with EEG recording to compare the effect of incentive valence (reward or punishment), as well as the magnitude of incentives on visual WM. Behavioral results revealed that the presence of incentive signals improved WM precision when compared with no‐incentive condition, and compared with punishing cues, rewarding cues led to greater facilitation in WM precision, as well as confidence ratings afterward. Moreover, event related potential (ERP) results suggested that compared with punishment, reward led to an earlier latency of late positive component (LPC), a larger amplitude of contingent negative variation (CNV) during the expectation period, and a larger P300 amplitude during the sample and delay periods. Furthermore, reward advantage over punishment in behavioral and neural results were correlated, such that individuals with larger CNV difference between reward and punishment conditions also report greater distinction in confidence ratings between the two conditions. In sum, our results demonstrate what and how rewarding cues cause more beneficial effects than punishing cues when incentivizing visual WM. Prospect Theory has long been proposed that people were more sensitive to punishment than reward. However, we challenged it using a money‐incentive free‐recall working memory task and observed the advantage of rewarding over punishing cues when incentivizing working memory from results of both behaviors and electroencephalography. [ABSTRACT FROM AUTHOR]

Working memory (WM) deficits have been widely documented in schizophrenia (SZ), and almost all existing studies attributed the deficits to decreased capacity as compared to healthy control (HC) subjects. Recent developments in WM research suggest that other components, such as precision, also mediate behavioral performance. It remains unclear how different WM components jointly contribute to deficits in schizophrenia. We measured the performance of 60 SZ (31 females) and 61 HC (29 females) in a classical delay-estimation visual working memory (VWM) task and evaluated several influential computational models proposed in basic science of VWM to disentangle the effect of various memory components. We show that the model assuming variable precision (VP) across items and trials is the best model to explain the performance of both groups. According to the VP model, SZ exhibited abnormally larger variability of allocating memory resources rather than resources or capacity per se. Finally, individual differences in the resource allocation variability predicted variation of symptom severity in PSZ, highlighting its functional relevance to schizophrenic pathology. This finding was further verified using distinct visual features and subject cohorts. These results provide an alternative view instead of the widely accepted decreased-capacity theory and highlight the key role of elevated resource allocation variability in generating atypical VWM behavior in schizophrenia. Our findings also shed new light on the utility of Bayesian observer models to characterize mechanisms of mental deficits in clinical neuroscience. Author summary: Working memory is a core cognitive function related to a broad range of cognitive domains such as problem-solving, attention, executive control, and IQ. Although working memory deficits have been well-documented in schizophrenia, the underlying mechanisms remain unclear. Conventional working memory theories attribute working memory deficits in schizophrenia to their reduced memory capacity, overlooking the potential roles of other memory components, such as precision. In this study, we take the approach of computational psychiatry and use computational modeling to uncover the major determinants of working memory deficits. We assess working memory performance of a large cohort of participants (60 schizophrenia patients and 61 demographic matched healthy controls) and evaluate multiple mainstream computational models of visual working memory. The variable precision model turns out to be the best model for both groups. We further find that the poorer performance of schizophrenia patients arises from heterogeneous distribution of memory resources when encoding items in memory. This resource allocation variability can also predict symptom severity in schizophrenia. Our study highlights the use of computational models in psychiatric researches. [ABSTRACT FROM AUTHOR]

Attention can be deployed among external sensory stimuli or internal working memory (WM) representations, and recent primate studies have revealed that these external and internal selections share a common neural basis in the prefrontal cortex (PFC). However, it remains to be elucidated how PFC implements these selections, especially in humans. The present study aimed to further investigate whether PFC responded differentially to the peripheral and central retrospective cues (retro-cues) that induced attention selection among WM representations. To achieve this, we combined magnetoencephalography (MEG, Experiment 1) and transcranial magnetic stimulation (TMS, Experiment 2) with an orientation-recall paradigm. Experiment 1 found that a peripheral retro-cue with 100% reliability had a greater benefit on WM performance than a central retro-cue, while this advantage of peripheral over central cues vanished when the cue reliability dropped to 50% (non-informative). MEG source analysis indicated that the 100% peripheral retro-cue elicited earlier (∼125 ms) PFC responses than the central retro-cue (∼275 ms). Meanwhile, Granger causality analysis showed that PFC had earlier (0–200 ms) top-down signals projecting to the superior parietal lobule (SPL) and the lateral occipital cortex (LOC) after the onset of peripheral retro-cues, while these top-down signals appeared later (300–500 ms) after the onset of central retro-cues. Importantly, PFC activity within this period of 300–500 ms correlated with the peripheral advantage in behavior. Moreover, Experiment 2 applied TMS at different time points to test the causal influence of brain activity on behavior and found that stimulating PFC at 100 ms abolished the behavioral benefit of the peripheral retro-cue, as well as its advantage over the central retro-cue. Taken together, our results suggested that the advantage of peripheral over central retro-cues in the mnemonic domain is realized through faster top-down control from PFC, which challenged traditional opinions that the top-down control of attention on WM required at least 300 ms to appear. The present study highlighted that in addition to the causal role of PFC in attention selection of WM representations, timing was critical as well and faster was better. • Attention can be directed externally or internally, controlled by the prefrontal cortex (PFC). • Working memory (WM) representations and performance can be facilitated by retro-cues. • Peripheral retro-cue in WM (load 2) enhanced WM and activated PFC earlier than central retro-cue. • Early PFC activity causally influenced behavior, confirmed by TMS experiment. • Findings suggest separate processes for attention and WM, with PFC's vital involvement. [ABSTRACT FROM AUTHOR]

• Lateral occipital complex (LOC) retains trial-wise memory precision in visual working memory. • LOC communicates with the prefrontal cortex when working memory load increases. • Neural activity in LOC predicts individual model-based memory precision. The neural mechanisms associated with the limited capacity of working memory (WM) has long been studied, but it is still unclear which neural regions are associated with the precision of visual WM. Here, an orientation recall task for estimating the trial-wise precision of visual WM was performed and then repeated two weeks later in an fMRI scanner. Results showed that activity in frontal and parietal regions during WM maintenance scaled with WM load, but not with the precision of WM (i.e., recall error in radians). Conversely, activity in the lateral occipital complex (LOC) during WM maintenance was not affected by memory load, but rather, correlated with WM precision on a trial-by-trial basis. Moreover, activity in LOC also correlated with the individual participant's precision of WM from a separate behavioral experiment. Interestingly, a region within the prefrontal cortex, the inferior frontal junction (IFJ), exhibited greater functional connectivity with LOC when the WM load increased. Together, our findings provide unique evidence that the LOC supports visual WM precision, while communication between the IFJ and LOC varies based on WM load demands. These results suggest an intriguing possibility that distinct neural mechanisms may be associated with general content (load) or detailed information (precision) of WM. [ABSTRACT FROM AUTHOR]

We investigated visual working memory (VWM) with a whole-report task, where participants were asked to sequentially recall all the items in an order either chosen by themselves (free recall) or randomly chosen by the computer (forced recall). Comparisons between free and forced recalls helped us understand important but largely neglected aspects of VWM, such as inhomogeneity (different levels of precision) and between-item interference. One unique part of our task was the introduction of a separate item-selection stage before each recall, during which participants located the next item to recall. Their mouse trajectory was recorded and served as a dynamic measure of between-item interference over time. We found a free-recall benefit: the overall precision of all items is higher in free recall than in forced recall. Meanwhile, during item-selection, free recall is associated with faster localization of the target and less interference from the other items in memory. We also found evidence for inhomogeneity and discuss the connection of inhomogeneity and between-item interference to the free-recall benefit. [ABSTRACT FROM AUTHOR]