More attention with less working memory: The active inhibition of attended but outdated information

Decreased Memory-Related Regional Cerebral Perfusion in Severe Obstructive Sleep Apnea with a Mild Cognitive Impairment During Wakefulness

Purpose

Previous studies have found that obstructive sleep apnea (OSA) can induce cognitive impairment (CI). However, the exact mechanisms of CI development in patients with OSA remains unclear. We investigated the neuropathological basis of CI development by examining changes in cerebral blood perfusion.

Patients and Methods

Thirty-five patients with untreated OSA (15 with CI and 20 without CI [NCI]) and 15 good sleepers (GS) diagnosed using polysomnography were recruited. All participants underwent resting state brain scans in a Siemens 3.0 Tesla magnetic resonance imaging scanner with a pulsed arterial spin labeling sequence and completed a battery of neuropsychological tests.

Results

Compared to the regional cerebral blood flow (rCBF) values in the GS group, both the CI and NCI groups exhibited lower rCBF values in the bilateral inferior temporal, left lingual, and right medial and paracingulate gyri, as well as higher rCBF values in the bilateral middle frontal gyrus (p < 0.05 in all cases). Compared to the rCBF values in the NCI group, the CI group had lower rCBF values in the bilateral inferior temporal and left lingual gyri, and higher rCBF values in the right rectus and right middle orbital frontal gyri (p < 0.05 in all cases). In the CI group, rCBF values in the bilateral inferior temporal (right, p = 0.025; left, p = 0.005) and left lingual gyri (p = 0.018) were positively associated with the delayed memory scores, and rCBF values in the left inferior temporal gyrus positively correlated with the attention scores (p = 0.011).

Conclusion

Regions with abnormal perfusion in the NCI and CI groups were mostly memory-related. Blood perfusion in the bilateral inferior temporal and left lingual gyri decreased in the following order: GS > OSA-NCI > OSA-CI. These findings provide blood perfusion-level insights into the neuropathological basis of OSA-CI development.

The role of middle frontal gyrus in working memory retrieval by the effect of target detection tasks: a simultaneous EEG-fMRI study

Maintained working memory (WM) representations have been shown to influence visual target detection selection, while the effect of the visual target detection process on WM retrieval remains largely unknown. In the current research, we used the dual-paradigm of the visual target detection task and the delayed matching task (DMT), which contained the following four conditions: the match condition: the DMT target contained the detection target; the mismatch condition: the DMT target contained the detection distractor; the neutral condition: only the detection target was presented; the catch condition: only the DMT target was presented. Twenty-six subjects were recruited in the experiment with simultaneous EEG-fMRI data. Behaviorally, faster responses were found in the mismatch condition than in the match and neutral conditions. The EEG data found a greater parieto-occipital N1 component in the mismatch condition compared to the neutral condition, and a greater frontal N2 component in the match condition than in the mismatch condition. Moreover, compared to the match and neutral conditions, weaker activations of the bilateral middle frontal gyrus (MFG) were observed in the mismatch condition. And the representational similarity analysis (RSA) revealed significant differences in the representational patterns of the bilateral MFG between mismatch and match conditions, as well as in the representational patterns of the left MFG between mismatch and neutral conditions. Additionally, the left MFG may be the brain source of the N1 component in the mismatch condition. These findings suggest that the mismatch between the DMT target and detection target affects early attention allocation and attentional control in WM retrieval, and the MFG may play an important role in WM retrieval by the effect of the target detection task. In conclusion, our work deepens the understanding of the neural mechanisms by which visual target detection affects WM retrieval.

The object as the unit for state switching in visual working memory

This study aimed to determine the unit for switching representational states in visual working memory (VWM). Two opposing hypotheses were investigated: (a) the unit of switching being a feature (feature-based hypothesis), and (b) the unit of switching being an object (object-based hypothesis). Participants (N = 180) were instructed to hold two features from either one or two objects in their VWM. The memory-driven attentional capture effect, suggesting that actively held information in VWM can cause attention to be drawn towards matched distractors, was employed to assess representational states of the first and second probed colors (indicated by a retro-cue). The results showed that only the feature indicated to be probed first could elicit memory related capture for the condition of separate objects. Importantly, features from an integrated object could guide attention regardless of the probe order. These findings were observed across three experiments involving features of different dimensions, same dimensions, or perceptual objects defined by Gestalt principles. They provide convergent evidence supporting the object-based hypothesis by indicating that features within a single object cannot exist in different states.

Can irrelevant self-related information in working memory be actively suppressed?

To utilize the resource of working memory efficiently, the brain actively suppresses irrelevant information to focus cognitive resources on the task at hand. However, whether task-irrelevant self-related information can be suppressed is still an open question. This study explores the inhibitory effects of various types of identity-associated information (self, friend, stranger) with an irrelevant distracting paradigm, in which participants are required to memorize the color while ignoring the shape during a memory array. In the subsequent test array, participants are asked to judge whether the color of the test item is the same as the memorized one, while the ignored shape features could also change. The results are as follows. (1) Self-associated information survived the inhibitory effect no matter whether the interstimulus interval (ISI) was short or long. (2) Stranger-associated information remained inhibitory effect in a long ISI (3000 ms). The results indicate that self-associated information can bypass the executive system and remain active in working memory processing.

Children exhibit superior memory for attended but outdated information compared to adults

Research on the development of cognitive selectivity predominantly focuses on attentional selection. The present study explores another facet of cognitive selectivity-memory selection-by examining the ability to filter attended yet outdated information in young children and adults. Across five experiments involving 130 children and 130 adults, participants are instructed to use specific information to complete a task, and then unexpectedly asked to report this information in a surprise test. The results consistently demonstrate a developmental reversal-like phenomenon, with children outperforming adults in reporting this kind of attended yet outdated information. Furthermore, we provide evidence against the idea that the results are due to different processing strategies or attentional deployments between adults and children. These results suggest that the ability of memory selection is not fully developed in young children, resulting in their inefficient filtering of attended yet outdated information that is not required for memory retention.

Flexibility Retained: Unimpaired Updating of Expectations in Schizophrenia

Flexibly and actively updating expectations based on feedback is crucial for navigating daily life. Previous research has shown that people with schizophrenia (PSZ) have difficulty adjusting their expectations. However, there are studies suggesting otherwise. To explore this further, we used a novel trial-based expectation updating paradigm called attribute amnesia. In the task, the participants needed to report the location of a target stimulus among distractors in pre-surprise trials. In the surprise trial, they were unexpectedly asked to report the identity of the target before reporting its location. Afterward, control trials were conducted whereby the participants were asked the same questions as in the surprise trial. Notably, the surprise trial and control trials were nearly identical, except that the participants expected to be asked about identity information in the control trials but not in the surprise trial. Thus, an improvement in identity reporting accuracy in the control trials in comparison with the surprise trial indicated active updating of expectations. In the current study, a total of 63 PSZ and 60 healthy control subjects (HCS) were enrolled. We found that both the PSZ and the HCS were unable to report information that they had fully attended to (i.e., identity) in the surprise trial. However, both groups showed a significant improvement in reporting identity information even in the first control trial. Critically, there was no significant difference in the magnitude of improvement between the two groups. The current findings indicate that PSZ have the ability to update their expectations as quickly and flexibly as HCS, at least in the context of the current task. The possible factors that might contribute to the discrepancy regarding expectation updating are discussed.

Attention with or without working memory: mnemonic reselection of attended information

Attention has been regarded as the 'gatekeeper' controlling what information gets selected into working memory. However, a new perspective has emerged with the discovery of attribute amnesia, a phenomenon revealing that people are frequently unable to report information they have just attended to moments ago. This report failure is thought to stem from a lack of consolidating the attended information into working memory, indicating a dissociation between attention and working memory. Building on these findings, a new concept called memory reselection is proposed to describe a secondary round of selection among the attended information. These discoveries challenge the conventional view of how attention and working memory are related and shed new light onto modeling attention and memory as dissociable processes.

Working-Memory-Guided Attention Competes with Exogenous Attention but Not with Endogenous Attention

Recent research has extensively investigated working memory (WM)-guided attention, which is the phenomenon of attention being directed towards information in the external environment that matches the content stored in WM. While prior studies have focused on the potential influencing factors of WM-guided attention, little is known about the nature of it. This attention system exhibits characteristics of two classical distinct attention systems: exogenous attention and endogenous attention, as it can operate automatically like exogenous attention yet persist for a long time and be modulated by cognitive resources like endogenous attention. Thus, the current study aimed to explore the mechanism of WM-guided attention by testing whether it competed with exogenous attention, endogenous attention, or both. Two experiments were conducted within a classic WM-guided attention paradigm. Experiment 1 included an exogenous cue and revealed an interaction between WM-guided attention and exogenous attention. Experiment 2 replaced the exogenous cue with an endogenous cue and demonstrated that endogenous attention had no impact on WM-guided attention. These findings indicate that WM-guided attention shares mechanisms with exogenous attention to some extent while operating in parallel with endogenous attention.