Long-term memory guides resource allocation in working memory

Long-term memory facilitates spontaneous memory usage through multiple pathways

Memories scaffold ongoing cognition and behavior.1,2,3,4,5 Surprisingly, when given the "sensorimnemonic" choice6 between using working memory (WM) and sampling sensory information from the environment, reliance on WM is much lower than expected.7,8,9,10,11,12,13 Here, we ask how the availability of long-term memory (LTM), alongside WM, changes how participants spontaneously sample sensory information in service of memory encoding, rely on their memory, and coordinate the two. Participants copied a model display by selecting realistic objects from a resource pool and placing them into a workspace.13,14 We tracked head, hand, and eye movements during free-flowing interactions with the virtual environment. To test the contributions of LTM engagement during natural behavior, we manipulated the repetition of stimulus arrangements over 2 days and used novel arrangements as a baseline. LTM availability had multiple consequences, resulting in an increased reliance on memory content. Further, LTM improved the efficiency of sensory sampling, evidenced by shorter encoding times of repeated objects. In the extreme, mnemonic sampling directly substituted sensory sampling, as some objects were not sampled at all before successful copying in repeated trials. These changes unfolded concurrently within the same task. Finally, incidentally formed memories during the task were accessible for explicit report. Performance in a subsequent surprise memory task showed that participants placed more objects correctly in repeated arrangements. Our findings demonstrate concurrent spontaneous deployment of multiple LTM mechanisms, alongside WM and sensory processing, showcasing impressive flexibility in balancing the engagement of sensory and different types of memory information to guide adaptive behavior. VIDEO ABSTRACT.

Not all objects are created equal: The object benefit in visual working memory is supported by greater recollection-like memory, but only for memorable objects

Visual working memory is thought to have a fixed capacity limit. However, recent evidence suggests that a greater number of real-world objects than simple features (i.e., colors) can be maintained, an effect termed the object benefit. Here, we examined whether this object benefit in visual working memory is due to qualitatively different memory processes employed for meaningful stimuli compared to simple features. In online samples of young adults, real-world objects were better remembered than colors, had higher measures of recollection, and showed a greater proportion of high-confidence responses (Exp. 1). Objects were also remembered better than their scrambled counterparts (Exp. 2), suggesting that this benefit is related to semantic information, rather than visual complexity. Critically, the specific objects that were likely to be remembered with high confidence were highly correlated across experiments, consistent with the idea that some objects are more memorable than others. Visual working memory performance for the least-memorable objects was worse than that of colors and scrambled objects. These findings suggest that real-world objects give rise to recollective, or at least high-confidence, responses at retrieval that may depend on activation of semantic features, but that this effect is limited to certain objects.

Integration of history information Drives Serial Dependence and Stabilizes Working Memory Representations

Serial dependence has shown seemingly contradictory effects on visual perception and working memory. While serial dependence promotes perpetual and mnemonic stability, it biases behavioral reports toward prior information. The neural mechanisms that drive both biasing and adaptive stabilizing effects are not well understood. We proposed and tested a reactivation and integration mechanism that can account for these contradictory effects. We used multivariate pattern analyses of EEG data (26 human participants, 17 females, 9 males) to examine the reactivation of prior reported orientation during the delay period of a visual working memory task. The reactivation strength of prior reports, but not prior sensory items, was predictive of the magnitude of serial dependency biases. These reactivated representations integrated with the representation of the current memory item and improved the ability to decode the current contents of memory. Overall, our data provide convergent evidence suggesting that prior reports in a visual working memory task are reactivated on the subsequent trial and become integrated with current memory representations. This similarity-dependent reactivation mechanism drives both report biasing and stabilization effects attributed to serial dependence in working memory.

Familiarity enhances mnemonic precision but impairs mnemonic accuracy in visual working memory

Prior stimulus familiarity has a variety of effects on visual working memory representations and processes. However, it is still unclear how familiarity interacts with the veridical correspondence between mnemonic representation and external stimuli. Here, we examined the effect of familiarity on two aspects of mnemonic correspondence, precision and accuracy, in visual working memory. Specifically, we used a hierarchical Bayesian method to model task performance in a change detection task with celebrity lookalikes (morphed faces between celebrities and noncelebrities with various ratios) as the memory stimuli. We found that familiarity improves memory precision by sharpening mnemonic representation but impairs memory accuracy by biasing mnemonic representation toward familiar faces (i.e., celebrity faces). These findings provide an integrated account of the puzzling celebrity sighting phenomena with the dissociable effects on mnemonic imprecision and bias and further highlight the importance of assessing these two aspects of memory correspondence in future research.

Little Support for Discrete Item Limits in Visual Working Memory

Some theorists argue that working memory is limited to a discrete number of items and that additional items are not encoded at all. Adam et al. (2017) presented evidence supporting this hypothesis: Participants reproduced visual features of up to six items in a self-chosen order. After the third or fourth response, error distributions were indistinguishable from guessing. I present four experiments with young adults (each N = 24) reexamining this finding. Experiment 1 presented items slowly and sequentially. Experiment 2 presented them simultaneously but longer than in the experiments of Adam et al. Experiments 3 and 4 exactly replicated one original experiment of Adam et al. All four experiments failed to replicate the evidence for guessing-like error distributions. Modeling data from individuals revealed a mixture of some who do and others who do not produce guessing-like distributions. This heterogeneity increases the credibility of an alternative to the item-limit hypothesis: Some individuals decide to guess on hard trials even when they have weak information in memory.

Moderating Effects of Self-Efficacy and Time Pressure on the Relationship Between Employee Aging and Work Performance

Purpose

The relationships among employee aging, working memory capacity, and task performance in the context of information technology were studied, and these investigations in turn provide insight into improving employee task performance and mitigating the negative effects of employee aging.

Participants and Methods

Based on the limited resource theory and the inhibitory deficit theory, a total of 296 valid questionnaires were collected and the relationships among the variables were examined using cascaded linear regression via SPSS 22.0.

Results

Aging negatively affects working memory capacity and task performance. Working memory capacity partially mediates the relationship between age and task performance. Time pressure can exacerbate the negative effects of age on task performance, and self-efficacy mitigates the negative effects of age on task performance.

Discussion

Employee information system learning and training can be enhanced to ameliorate the negative impact of aging on task performance. IT-related work can be limited to a manageable level to reduce the negative effects of reduced working memory capacity. Employees’ internal motivation can be gradually cultivated, and employees can be guided toward the improvement of their IT self-efficacy.

Enhancing Visuospatial Working Memory Performance Using Intermittent Theta-Burst Stimulation Over the Right Dorsolateral Prefrontal Cortex

Noninvasive brain stimulation provides a promising approach for the treatment of neuropsychiatric conditions. Despite the increasing research on the facilitatory effects of this kind of stimulation on the cognitive processes, the majority of the studies have used the standard stimulation approaches such as the transcranial direct current stimulation and the conventional repetitive transcranial magnetic stimulation (rTMS) which seem to be limited in robustness and the duration of the transient effects. However, a recent specialized type of rTMS, theta-burst stimulation (TBS), patterned to mimic the natural cross-frequency coupling of the human brain, may induce robust and longer-lasting effects on cortical activity. Here, we aimed to investigate the effects of the intermittent TBS (iTBS), a facilitatory form of TBS, over the right DLPFC (rDLPFC), a brain area implicated in higher-order cognitive processes, on visuospatial working memory (VSWM) performance. Therefore, iTBS was applied over either the rDLPFC or the vertex of 24 healthy participants, in two separate sessions. We assessed VSWM performance using 2-back and 4-back visuospatial tasks before iTBS (at the baseline (BL), and after the iTBS. Our results indicate that the iTBS over the rDLPFC significantly enhanced VSWM performance in the 2-back task, as measured by the discriminability index and the reaction time. However, the 4-back task performance was not significantly modulated by iTBS. These findings demonstrate that the rDLPFC plays a critical role in VSWM and that iTBS is a safe and effective approach for investigating the causal role of the specific brain areas.

Disrupted population coding in the prefrontal cortex underlies pain aversion

The prefrontal cortex (PFC) regulates a wide range of sensory experiences. Chronic pain is known to impair normal neural response, leading to enhanced aversion. However, it remains unknown how nociceptive responses in the cortex are processed at the population level and whether such processes are disrupted by chronic pain. Using in vivo endoscopic calcium imaging, we identify increased population activity in response to noxious stimuli and stable patterns of functional connectivity among neurons in the prelimbic (PL) PFC from freely behaving rats. Inflammatory pain disrupts functional connectivity of PFC neurons and reduces the overall nociceptive response. Interestingly, ketamine, a well-known neuromodulator, restores the functional connectivity among PL-PFC neurons in the inflammatory pain model to produce anti-aversive effects. These results suggest a dynamic resource allocation mechanism in the prefrontal representations of pain and indicate that population activity in the PFC critically regulates pain and serves as an important therapeutic target.

Li et al. reveal that inflammatory pain disrupts the functional connectivity of neurons in the prelimbic prefrontal cortex (PL-PFC) and the overall nociceptive response. Ketamine, meanwhile, restores the functional connectivity of neurons in the PL-PFC in the inflammatory pain state to produce anti-aversive effects.