Interference Resolution Research Articles

The Neural Specificity of Interference Resolution in Phonological, Semantic, and Visual Domains at Different Ages.

The question of whether cognitive control is specific to certain domains or domain-general remains an extensively debated question at both cognitive and neural levels. This study examined the neural substrates associated with resistance to interference (RI) in phonological, semantic, and visual domains by using strictly matched tasks and determining the domain-general or domain-specific manner in which aging affects the neural substrates associated with RI. In an fMRI experiment, young and older participants performed a similarity judgment task with phonological, semantic, or visual interference buildup. For both age groups, domain-specific RI effects were observed at the univariate level, with increased involvement in the phonological domain of the right angular gyrus and the right lingual gyrus, in the semantic domain of the bilateral inferior frontal gyrus, the bilateral superior parietal and angular gyri and the left middle temporal gyrus, and in the visual domain of the middle/superior frontal gyri and occipital gyri. At the multivariate level, although RI effects could be decoded from neural patterns in the bilateral inferior frontal gyrus for all domains and age groups, between-domain prediction of RI conditions was associated with Bayesian evidence for the null hypothesis. This study supports the domain specificity of neural substrates associated with RI while stressing its age independency.

The role of variation in phonological and semantic working memory capacities in sentence comprehension: neural evidence from healthy and brain-damaged individuals.

Research on the role of working memory (WM) in language processing has typically focused on WM for phonological information. However, considerable behavioral evidence supports the existence of a separate semantic WM system that plays a greater role in language processing. We review the neural evidence that supports the distinction between phonological and semantic WM capacities and discuss how individual differences in these capacities relate to sentence processing. In terms of neural substrates, findings from multivariate functional MRI for healthy participants and voxel-based lesion-symptom mapping for brain-damaged participants imply that the left supramarginal gyrus supports phonological WM, whereas the left inferior frontal gyrus (LIFG) and angular gyrus support semantic WM. In sentence comprehension, individual variation in semantic but not phonological WM related to performance in resolving semantic information and the LIFG region implicated in semantic WM showed fMRI activation during the resolution of semantic interference. Moreover, variation for brain-damaged participants in the integrity of a fiber tract supporting semantic WM had a greater relation to the processing of complex sentences than did the integrity of fiber tracts supporting phonological WM. Overall, the neural findings provide converging evidence regarding the distinction of these two capacities and the greater contribution of individual differences in semantic than phonological WM capacity to sentence processing.

Executive functioning in posttraumatic stress disorder: Understanding how inhibition, switching, and test modality affect reaction times.

Posttraumatic stress disorder (PTSD) has been linked to deficits in executive functioning, but the literature suggests these associations are inconsistent. Results vary depending on the task used, test modality, and the specific subdomain being measured, such as inhibitory control (interference resolution, response inhibition) or set shifting (task switching, rule switching). Notably, deficits are more consistently observed in computerized tasks that measure precise reaction times (RTs) than in classic paper-and-pencil measures, but few studies have parsed specific executive functioning deficits in PTSD using detailed analyses of RT data. The present study used a cued-switching Stroop Task to examine both interference resolution and task switching in 28 veterans with PTSD and 28 age-matched controls. Each trial required attending to a randomly presented cue and responding to the specified target while ignoring irrelevant or opposing information. Analyses of RT distributions estimated both Gaussian (normal) and ex-Gaussian (exponential) parameters. Veterans with PTSD had slower and more variable RTs than the controls on trials that required ignoring conflicting information (interference resolution, d' = .68). These effects were confined to the normal distribution, not to excessively slow responses (as estimated by ex-Gaussian parameters). Veterans with PTSD also showed modestly slower RTs on trials that required switching between cues, but Bayesian evidence for this was weak, and measures by ex-Gaussian parameters were not significant. These results highlight the importance of examining executive functioning in PTSD with a more nuanced approach, as clarity around these deficits may have important implications for future intervention and rehabilitation strategies. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

The resolution of proactive interference in a novel visual working memory task: A behavioral and pupillometric study.

Proactive interference (PI) occurs when previously learned information impairs memory for more recently learned information. Most PI studies have employed verbal stimuli, while the role of PI in visual working memory (VWM) has had relatively little attention. In the verbal domain, Johansson and colleagues (2018) found that pupil diameter - a real-time neurophysiological index of cognitive effort - reflects the accumulation and resolution of PI. Here we use a novel, naturalistic paradigm to test the behavioral and pupillary correlates of PI resolution for what-was-where item-location bindings in VWM. Importantly, in our paradigm, trials (PI vs. no-PI condition) are mixed in a block, and participants are naïve to the condition until they are tested. This design sidesteps concerns about differences in encoding strategies or generalized effort differences between conditions. Across three experiments (N = 122 total) we assessed PI's effect on VWM and whether PI resolution during memory retrieval is associated with greater cognitive effort (as indexed by the phasic, task-evoked pupil response). We found strong support for PI's detrimental effect on VWM (even with our spatially distributed stimuli), but no consistent link between interference resolution and effort during memory retrieval (this, even though the pupil was a reliable indicator that higher-performing individuals tried harder during memory encoding). We speculate that when explicit strategies are minimized, and PI resolution relies primarily on implicit processing, the effect may not be sufficient to trigger a robust pupillometric response.

Tracking Components of Bilingual Language Control in Speech Production: An fMRI Study Using Functional Localizers.

When bilingual speakers switch back to speaking in their native language (L1) after having used their second language (L2), they often experience difficulty in retrieving words in their L1. This phenomenon is referred to as the L2 after-effect. We used the L2 after-effect as a lens to explore the neural bases of bilingual language control mechanisms. Our goal was twofold: first, to explore whether bilingual language control draws on domain-general or language-specific mechanisms; second, to investigate the precise mechanism(s) that drive the L2 after-effect. We used a precision fMRI approach based on functional localizers to measure the extent to which the brain activity that reflects the L2 after-effect overlaps with the language network (Fedorenko et al., 2010) and the domain-general multiple demand network (Duncan, 2010), as well as three task-specific networks that tap into interference resolution, lexical retrieval, and articulation. Forty-two Polish-English bilinguals participated in the study. Our results show that the L2 after-effect reflects increased engagement of domain-general but not language-specific resources. Furthermore, contrary to previously proposed interpretations, we did not find evidence that the effect reflects increased difficulty related to lexical access, articulation, and the resolution of lexical interference. We propose that difficulty of speech production in the picture naming paradigm-manifested as the L2 after-effect-reflects interference at a nonlinguistic level of task schemas or a general increase of cognitive control engagement during speech production in L1 after L2.

Interference Analysis of Weather Radar at The Meteorological Station

This research aims to analyze the disturbances that occur at the Sultan Syarif Kasim II Meteorological Station Weather Radar and provide appropriate treatment to stop the source of the disturbance. For this reason, the following steps are arranged: Literature studies, preparation for mitigating interference, measurement, interference analysis, and interference resolution. After applying measurements, the following results were obtained: The interference location point is on the azimuth line (8.07° and 37.84°), Noise floor level -107.3 dBm at a frequency of 6500 MHz when SSID PermanaNET#02 5825 MHz is on, noise floor level -111.1 dBm at a frequency of 6500 MHz when SSID PermanaNET#02 5825 MHz is off, distance between BMKG Radar station to Point of Presence (PoP) ISP PT. Medianusa Permana is very close ±200 meters, antenna SSID PermanaNET#02 5825 MHz pointing to the BMKG Radar Station, and sensitivity of the EEC DWSR–2500C Radar Device is -113 dBm. Interference at the 6500 MHz radar frequency comes from the Out Of Band Emission frequency 5825 MHz (SSID PermanaNET#02). Following this, the interference is mitigated by the off-air method, which is deactivation of the PermanaNET SSID#02 device.

Insights into attention and memory difficulties in post-COVID syndrome using standardized neuropsychological tests and experimental cognitive tasks

The COVID-19 pandemic has given rise to post-acute cognitive symptoms, often described as ‘brain fog’. To comprehensively grasp the extent of these issues, we conducted a study integrating traditional neuropsychological assessments with experimental cognitive tasks targeting attention control, working memory, and long-term memory, three cognitive domains most commonly associated with ‘brain fog’. We enrolled 33 post-COVID patients, all self-reporting cognitive difficulties, and a matched control group (N = 27) for cognitive and psychological assessments. Our findings revealed significant attention deficits in post-COVID patients across both neuropsychological measurements and experimental cognitive tasks, evidencing reduced performance in tasks involving interference resolution and selective and sustained attention. Mild executive function and naming impairments also emerged from the neuropsychological assessment. Notably, 61% of patients reported significant prospective memory failures in daily life, aligning with our recruitment focus. Furthermore, our patient group showed significant alterations in the psycho-affective domain, indicating a complex interplay between cognitive and psychological factors, which could point to a non-cognitive determinant of subjectively experienced cognitive changes following COVID-19. In summary, our study offers valuable insights into attention challenges faced by individuals recovering from COVID-19, stressing the importance of comprehensive cognitive and psycho-affective evaluations for supporting post-COVID individuals.

Distributed Sensitivity and Critical Interference Power Analysis of Multi-Degree-of-Freedom Navigation Interference for Global Navigation Satellite System Array Antennas.

Current research on the interference of GNSS (Global Navigation Satellite System) array antennas focuses on the single interference effect and the improvement of interference hardware capability, while the multi-degree-of-freedom (DOF) interference model and mechanism remain to be fully studied. Aiming at this problem, this paper analyzes the preconditions for the definition of anti-jamming degrees of freedom and the characteristics of super-DOF interference through formula derivation and simulation. First, by analyzing the influence of the number of interfering signals on the angular resolution, the prerequisite of the definition of anti-interference degrees of freedom in the airspace is proposed. Second, the definition of anti-interference degrees of freedom is used to calculate the change rule of the critical power of the interference under different numbers of interfering signals. Finally, the influence of super-DOF interference on the array antenna is analyzed. The results show that the prerequisite for the anti-interference freedom of the array antenna is that the distribution interval of the interfering signal is greater than 15°, taking a four-array element uniform circular array antenna as an example. The critical interference power of the array antenna decreases by about 15 dB when the number of interfering signals exceeds the degrees of freedom of the array antenna's interference immunity, provided that the interference resolution is satisfied. The conclusions of this paper give the critical power change rule of multi-DOF interference and the effect of super-DOF interference, as well as the prerequisites for the setting of interference signals, which can be used, for example, in the deployment of distributed interference sources and the development of anti-jamming algorithms.

Mapping expectancy-based appetitive placebo effects onto the brain in women

Suggestions about hunger can generate placebo effects on hunger experiences. But, the underlying neurocognitive mechanisms are unknown. Here, we show in 255 women that hunger expectancies, induced by suggestion-based placebo interventions, determine hunger sensations and economic food choices. Functional magnetic resonance imaging in a subgroup (n = 57/255) provides evidence that the strength of expecting the placebo to decrease hunger moderates medial prefrontal cortex activation at the time of food choice and attenuates ventromedial prefrontal cortex (vmPFC) responses to food value. Dorsolateral prefrontal cortex activation linked to interference resolution formally mediates the suggestion-based placebo effects on hunger. A drift-diffusion model characterizes this effect by showing that the hunger suggestions bias participants’ food choices and how much they weigh tastiness against the healthiness of food, which further moderates vmPFC–dlPFC psychophysiological interactions when participants expect decreased hunger. Thus, suggestion-induced beliefs about hunger shape hunger addressing economic choices through cognitive regulation of value computation within the prefrontal cortex.

Modulating Complex Sentence Processing in Aphasia Through Attention and Semantic Networks.

Lexical processing impairments such as delayed and reduced activation of lexical-semantic information have been linked to syntactic processing disruptions and sentence comprehension deficits in individuals with aphasia (IWAs). Lexical-level deficits can also preclude successful lexical encoding during sentence processing and amplify the processing costs of similarity-based interference during syntactic retrieval. We investigate whether two manipulations to engage attention and pre-activate semantic features of a target (to-be-retrieved) noun will (a) boost lexical activation during initial lexical encoding and (b) facilitate syntactic dependency linking through improved resolution of interference in IWAs and neurologically unimpaired age-matched controls (AMCs). Eye-tracking-while-listening with a visual world paradigm was used to investigate whether semantic and attentional manipulations modulated initial lexical processing and downstream syntactic retrieval of the direct-object noun in object-relative sentences. In the attention and semantic manipulations, the AMC group showed no changes in initial lexical access levels; however, gaze patterns revealed clear facilitations in dependency linking and interference resolution. In the IWA group, the attentional cue increased and maintained activation of N1 with modest facilitations in dependency linking. In the semantic condition, IWA results showed a greater degree of facilitation during dependency linking. The results suggest that attention and semantic activation are parameters that may be manipulated to strengthen encoding of lexical representations to facilitate retrieval (i.e., dependency linking) and mitigate similarity-based interference. In IWAs, these manipulations may help to reduce lexical processing deficits that can preclude successful encoding.

The many facets of inhibitory control and their role in syntactic selection

AbstractThere is accumulating evidence that distinct forms of domain-general inhibition underlie the selection of lexical candidates from among co-activated representations in single-word production. It is less clear whether similar control processes are engaged in the resolution of syntactic conflict in sentence production. This study assessed the relative contribution of three types of inhibitory control operating at different stages of information processing to syntactic interference resolution in an active-passive voice production task. Inhibition of response execution (the anti-saccade effect) and resolution of representational conflict (the flanker effect) were related to the occurrence of repairs and sentence onset latencies in passive voice trials. The results suggest not only that general-purpose mechanisms may be in place that resolve conflict regardless of whether it stems from syntactic or non-syntactic (non-verbal) representations, but also that they operate at dissociable processing stages.

Altered age-related alpha and gamma prefrontal-occipital connectivity serving distinct cognitive interference variants

The presence of conflicting stimuli adversely affects behavioral outcomes, which could either be at the level of stimulus (Flanker), response (Simon), or both (Multisource). Briefly, flanker interference involves conflicting stimuli requiring selective attention, Simon interference is caused by an incongruity between the spatial location of the task-relevant stimulus and prepotent motor mapping, and multisource is combination of both. Irrespective of the variant, interference resolution necessitates cognitive control to filter irrelevant information and allocate neural resources to task-related goals. Though previously studied in healthy young adults, the direct quantification of changes in oscillatory activity serving such cognitive control and associated inter-regional interactions in healthy aging are poorly understood. Herein, we used an adapted version of the multisource interference task and magnetoencephalography to investigate age-related alterations in the neural dynamics governing both divergent and convergent cognitive interference in 78 healthy participants (age range: 20-66 years). We identified weaker alpha connectivity between bilateral visual and right dorsolateral prefrontal cortices (DLPFC) and left dorsomedial prefrontal cortices (dmPFC), as well as weaker gamma connectivity between bilateral occipital regions and the right dmPFC during flanker interference with advancing age. Further, an age-related decrease in gamma power was observed in the left cerebellum and parietal region for Simon and differential interference effects (i.e., flanker-Simon), respectively. Moreover, the superadditivity model showed decreased gamma power in the right temporoparietal junction (TPJ) with increasing age. Overall, our findings suggest age-related declines in the engagement of top-down attentional control secondary to reduced alpha and gamma coupling between prefrontal and occipital cortices.

Neural correlates of the sound facilitation effect in the modified Simon task in older adults.

The ability to resolve interference declines with age and is attributed to neurodegeneration and reduced cognitive function and mental alertness in older adults. Our previous study revealed that task-irrelevant but environmentally meaningful sounds improve performance on the modified Simon task in older adults. However, little is known about neural correlates of this sound facilitation effect. Twenty right-handed older adults [mean age = 72 (SD = 4), 11 female] participated in the fMRI study. They performed the modified Simon task in which the arrows were presented either in the locations matching the arrow direction (congruent trials) or in the locations mismatching the arrow direction (incongruent trials). A total of 50% of all trials were accompanied by task-irrelevant but environmentally meaningful sounds. Participants were faster on the trials with concurrent sounds, independently of whether trials were congruent or incongruent. The sound effect was associated with activation in the distributed network of auditory, posterior parietal, frontal, and limbic brain regions. The magnitude of the behavioral facilitation effect due to sound was associated with the changes in activation of the bilateral auditory cortex, cuneal cortex, and occipital fusiform gyrus, precuneus, left superior parietal lobule (SPL) for No Sound vs. Sound trials. These changes were associated with the corresponding changes in reaction time (RT). Older adults with a recent history of falls showed greater activation in the left SPL than those without falls history. Our findings are consistent with the dedifferentiation hypothesis of cognitive aging. The facilitatory effect of sound could be achieved through recruitment of excessive neural resources, which allows older adults to increase attention and mental alertness during task performance. Considering that the SPL is critical for integration of multisensory information, individuals with slower task responses and those with a history of falls may need to recruit this region more actively than individuals with faster responses and those without a fall history to overcome increased difficulty with interference resolution. Future studies should examine the relationship among activation in the SPL, the effect of sound, and falls history in the individuals who are at heightened risk of falls.

The effect of time on lexical and syntactic processing in aphasia.

Processing deficits at the lexical level, such as delayed and reduced lexical activation, have been theorized as the source of breakdowns in syntactic operations and thus contribute to sentence comprehension deficits in individuals with aphasia (IWA). In the current study, we investigate the relationship between lexical and syntactic processing in object-relative sentences using eye-tracking while listening in IWA. We explore whether manipulating the time available to process a critical lexical item (the direct-object noun) when it is initially heard in a sentence has an immediate effect on lexical access as well as a downstream effect on syntactic processing. To achieve this aim, we use novel temporal manipulations to provide additional time for lexical processing to occur. In addition to exploring these temporal effects in IWA, we also seek to understand the effect that additional time has on sentence processing in neurotypical age-matched adults (AMC). We predict that the temporal manipulations designed to provide increased processing time for critical lexical items will 1) enhance lexical processing of the target noun, 2) facilitate syntactic integration, and 3) improve sentence comprehension for both IWA and AMC. We demonstrate that strengthening lexical processing via the addition of time can affect lexical processing and facilitate syntactic retrieval of the target noun and lead to enhanced interference resolution in both unimpaired and impaired systems. In aphasia, additional time can mitigate impairments in spreading activation thereby improving lexical access and reducing interference during downstream dependency linking. However, individuals with aphasia may require longer additions of time to fully realize these benefits.

Better together: novel methods for measuring and modeling development of executive function diversity while accounting for unity.

Executive functions (EFs) are linked to positive outcomes across the lifespan. Yet, methodological challenges have prevented precise understanding of the developmental trajectory of their organization. We introduce novel methods to address challenges for both measuring and modeling EFs using an accelerated longitudinal design with a large, diverse sample of students in middle childhood (N = 1,286; ages 8 to 14). We used eight adaptive assessments hypothesized to measure three EFs, working memory, context monitoring, and interference resolution. We deployed adaptive assessments to equate EF challenge across ages and a data-driven, network analytic approach to reveal the evolving diversity of EFs while simultaneously accounting for their unity. Using this methodological paradigm shift brought new precision and clarity to the development of these EFs, showing these eight tasks are organized into three stable components by age 10, but refinement of composition of these components continues through at least age 14.

Resolving Cross-modal Semantic Interference among Object Concepts Requires Medial Temporal Lobe Cortex

The ability to flexibly categorize object concepts is essential to semantic cognition because the features that make two objects similar in one context may be irrelevant and even constitute interference in another. Thus, adaptive behavior in complex and dynamic environments requires the resolution of feature-based interference. In the current case study, we placed visual and functional semantic features in opposition across object concepts in two categorization tasks. Successful performance required the resolution of functional interference in a visual categorization task and the resolution of visual interference in a functional categorization task. In Experiment 1, we found that patient D. A., an individual with bilateral temporal lobe lesions, was unable to categorize object concepts in a context-dependent manner. His impairment was characterized by an increased tendency to incorrectly group objects that were similar on the task-irrelevant dimension, revealing an inability to resolve cross-modal semantic interference. In Experiment 2, D. A.'s categorization accuracy was comparable to controls when lures were removed, indicating that his impairment is unique to contexts that involve cross-modal interference. In Experiment 3, he again performed as well as controls when categorizing simple concepts, suggesting that his impairment is specific to categorization of complex object concepts. These results advance our understanding of the anterior temporal lobe as a system that represents object concepts in a manner that enables flexible semantic cognition. Specifically, they reveal a dissociation between semantic representations that contribute to the resolution of cross-modal interference and those that contribute to the resolution of interference within a given modality.

Altered brain hemodynamic response and cognitive function after sleep deprivation: a functional near-infrared spectroscopy study

Aim: Acute sleep deprivation has revealed altered executive cognitive functioning, including attention, working memory, and interference resolution. In the present study, we investigated brain hemodynamics and cognitive function measures using functional near-infrared spectroscopy (fNIRS).Methods: fNIRS was used to record cortical brain activity in a resting state scan, flanker task, and n-Back tasks under well-rested (WR, >6.5 h sleep for ≥3 days) and sleep-deprived conditions (SD, 28 h awake) in a repeated-measures study in 20 participants (7 female, mean age 20.1 ± 0.413).Results: Our results indicate decreased accuracy rates in the flanker task in the SD condition, suggesting reduced response inhibition capacity. In the flanker task, a significant increase of beta estimates was observed in the SD condition in the right dl-PFC, suggesting potential compensation (BH-FDR corrected p = 0.0418, t(19) = 3.51). There were no significant differences between WR and SD in n-back task accuracy rates or reaction times or in Flanker task reaction times. Otherwise, functional connectivity strengths were not significantly different between the WR and SD sessions on a group-level analysis for the resting state and all tasks (BH-FDR correction, p > 0.05).Conclusion: Our results provide insight into how insufficient sleep patterns affect interference resolution, and that fNIRS can reveal functional connectivity differences inter- and intra-individually in SD conditions.

PD45-01 THE QUALITY OF LIFE IMPACT OF URETEROSCOPY FOR NEPHROLITHIASIS: RESULTS FROM THE ENDOUROLOGICAL SOCIETY TOWER RESEARCH COLLABORATIVE

You have accessJournal of UrologyCME1 Apr 2023PD45-01 THE QUALITY OF LIFE IMPACT OF URETEROSCOPY FOR NEPHROLITHIASIS: RESULTS FROM THE ENDOUROLOGICAL SOCIETY TOWER RESEARCH COLLABORATIVE Amanda Jones, Roby Daniel, Zili Zong, Jing Huang, and Justin Ziemba Amanda JonesAmanda Jones More articles by this author , Roby DanielRoby Daniel More articles by this author , Zili ZongZili Zong More articles by this author , Jing HuangJing Huang More articles by this author , and Justin ZiembaJustin Ziemba More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003358.01AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Urolithiasis is among the most common urological conditions, however, the quality-of-life impact of stone disease remains significantly understudied, particularly following surgical intervention. We prospectively captured patient-reported outcomes related to pain interference and social participation in the short term post-operative period to better understand the quality-of-life impact of ureteroscopy (URS). METHODS: Adults undergoing URS for renal/ureteral stones were eligible for inclusion (10/2020-09/2022). Two instruments were used to evaluate social participation and pain interference. Patients prospectively completed PROMIS Ability to participate in social roles and activities and Pain Interference instruments pre-operatively (POD 0) and via email on POD 1, 7, 14 and 30. Scores are reported as T-scores with a change of 5 (0.5 SD) considered clinically significant. RESULTS: 178 patients completed enrollment at POD 0 (POD 1=87, POD 7=83, POD 14=70, POD30=67). There were statistically significant differences in pain interference and social participation scores between all-time point comparisons (Figure 1 and 2, all p<0.05). Higher BMI was associated with both lower baseline social participation (OR -0.46; CI: -0.71- -0.20, p<0.01) and greater baseline pain interference (OR 0.52; CI: 0.22-0.81, p<0.01). Pre-operative stent is associated with greater baseline pain interference (OR 7.1; CI: 2.3–12; p=0.004). Having a stent post-operatively is associated with higher pain interference (OR 24; CI: 0.66-48, p<0.04) and lower social participation (OR -38; CI: -64--11; p<0.01) on POD 7. CONCLUSIONS: Ability to participate in social roles and activities declines immediately post-operatively, while pain interference sharply increases. However, patients return to baseline social participation and see resolution of pain interference by POD 14. Findings suggest both pre-operative and post-operative stents may be impacting patients’ quality of life. Source of Funding: NA © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e1162 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Amanda Jones More articles by this author Roby Daniel More articles by this author Zili Zong More articles by this author Jing Huang More articles by this author Justin Ziemba More articles by this author Expand All Advertisement PDF downloadLoading ...

Extra-hippocampal contributions to pattern separation.

Pattern separation, or the process by which highly similar stimuli or experiences in memory are represented by non-overlapping neural ensembles, has typically been ascribed to processes supported by the hippocampus. Converging evidence from a wide range of studies, however, suggests that pattern separation is a multistage process supported by a network of brain regions. Based on this evidence, considered together with related findings from the interference resolution literature, we propose the 'cortico-hippocampal pattern separation' (CHiPS) framework, which asserts that brain regions involved in cognitive control play a significant role in pattern separation. Particularly, these regions may contribute to pattern separation by (1) resolving interference in sensory regions that project to the hippocampus, thus regulating its cortical input, or (2) directly modulating hippocampal processes in accordance with task demands. Considering recent interest in how hippocampal operations are modulated by goal states likely represented and regulated by extra-hippocampal regions, we argue that pattern separation is similarly supported by neocortical-hippocampal interactions.

A Hybrid Grant NOMA Random Access for Massive MTC Service

Nonorthogonal multiple access (NOMA) is classified into grant-based (GB) random access (RA) and grant-free (GF) RA in 5G systems. GF NOMA RA allows user equipments (UE) to directly transmit data packet over uplink resources without grant information so that the signaling overhead is substantially reduced. This approach is suitable for small-size data packet IoT services. However, power collision interference resulting from uncoordinated resource selection leads to serious transmission failure in massive MTC scenarios. As a result, the number of transmissions and access delay are sharply increased. In this article, we make the best of the advantages of both GB RA and GF RA and propose a hybrid grant (HG) NOMA RA scheme to address the signaling overhead and power collision issues. The objective of the proposed scheme is to achieve an acceptable tradeoff among signaling overhead, access failure probability, and access delay. The UE selects the access resource without uplink grant, and the BS assists to avoid inter-NOMA power collision by limited interference resolution (IR) signaling. To comprehensively analyze the performance, the closed-form expression of outage probability is derived by adopting the order statistic theory and the sum of independent exponential distributions, and the maximum number of transmissions and access delay are theoretical analyzed. A Monte Carlo simulation framework is built to verify the theoretical analysis. Finally, the analytical and simulation results show that HG NOMA RA outperforms GB NOMA RA and GF NOMA RA in massive access scenarios.