Correlative comparison of visual working memory paradigms and associated models.

When studying the working memory (WM), the 'slot model' and the 'resource model' are two main theories used to describe how information retention occurs. The slot model shows that WM capacity consists of a certain number of predefined slots available for information storage. This theory explains that there is a binary condition during information recall in which information is either wholly maintained within a slot or forgotten. The resource model has a resolution-based approach, suggesting a continuous resource able to be distributed among a number of items in WM capacity. Recently hybrid models have been introduced, suggesting that WM may not strictly conform to only one model. Accordingly, to understand the relationship between two of the most widely used paradigms in WM evaluation, we implemented a correlational assessment in two different psychophysics tasks, an analog recall paradigm with sequential bar presentation and a delayed match-to-sample (DMS) task with checkerboard stimuli. Our study revealed significant correlations between WM performance in the DMS task and recall error, precision, and sources of errors in the sequential paradigm. Overall, the findings emphasize the importance of considering both tasks in understanding WM processes, as they shed light on the debate between the slot and resource models by revealing overlapping elements in both theories and the tasks used to evaluate WM capacity.

A mechanistic insight into sources of error of visual working memory in multiple sclerosis.

Working memory (WM) is one of the most affected cognitive domains in multiple sclerosis (MS), which is mainly studied by the previously established binary model for information storage (slot model). However, recent observations based on the continuous reproduction paradigms have shown that assuming dynamic allocation of WM resources (resource model) instead of the binary hypothesis will give more accurate predictions in WM assessment. Moreover, continuous reproduction paradigms allow for assessing the distribution of error in recalling information, providing new insights into the organization of the WM system. Hence, by utilizing two continuous reproduction paradigms, memory-guided localization (MGL) and analog recall task with sequential presentation, we investigated WM dysfunction in MS. Our results demonstrated an overall increase in recall error and decreased recall precision in MS. While sequential paradigms were better in distinguishing healthy control from relapsing-remitting MS, MGL were more accurate in discriminating MS subtypes (relapsing-remitting from secondary progressive), providing evidence about the underlying mechanisms of WM deficit in progressive states of the disease. Furthermore, computational modeling of the results from the sequential paradigm determined that imprecision in decoding information and swap error (mistakenly reporting the feature of other presented items) was responsible for WM dysfunction in MS. Overall, this study offered a sensitive measure for assessing WM deficit and provided new insight into the organization of the WM system in MS population.

Working memory is a system that temporarily stores and manipulates information used in tasks like decision-making and reasoning. Patients with multiple sclerosis ­ a condition that can affect the brain and spinal cord ­ often have impaired working memory, which can negatively affect their quality of life. Traditionally, working memory has been evaluated using tests that determine whether a patient can recall an item or not. In this approach, an incorrect response implies a complete absence of information regarding the specific item, resulting in a binary evaluation. More recently, researchers have shown that the precision of the memories people recall degrades gradually as they are asked to remember more things and that focusing on an item negatively affects recall precision for other items. This implies that working memory is reorganised flexibly between memorised items, a so-called 'resource model'. Unlike previous research, which favoured a binary model, Motahharynia et al. used a resource model to study visual working memory impairment in multiple sclerosis. The study participants consisted of healthy volunteers and patients with two subtypes of multiple sclerosis. Each participant completed one of two different types of test. In one, they were shown targets for short periods of time and then asked to pinpoint their position after they disappeared. In the other, participants were asked to memorise the orientation and colour of consecutively presented bars. The findings confirmed that multiple sclerosis patients had worse memory recall than people without the disease. However, computer modelling provided insights into the sources of error in working memory dysfunction, showing that the memory deficiency was due to imprecision in recalling information and 'swap errors', the phenomenon of mistakenly reporting the property of other memorised items. This rise in swap errors is likely due to an increase in unwanted signals, or noise, in the brains of multiple sclerosis patients. Motahharynia et al. have presented a sensitive way of measuring working memory deficiency. Importantly, the measurements were able to distinguish between different stages of multiple sclerosis. This could help doctors detect disease progression earlier, allowing for more timely and effective treatment interventions. This method could also be useful in the development and testing of drugs for therapy.

The benefit of intravenous immune globulin in the treatment of delayed radiation myelopathy.

Delayed radiation myelopathy (DRM) is a rare yet severe complication of radiotherapy. This condition has a progressive pattern that is often irreversible. Several therapeutic strategies have been introduced to alleviate disease complications, including corticosteroids, hyperbaric oxygen, anticoagulants, and antivascular endothelial growth factor (VEGF) agents. However, despite their beneficial effect, they have not been the definitive treatments for DRM. Here we present the case of a 55-year-old woman with a history of multiple myeloma who developed neurological complications 11 months after radiation therapy. As her radiologic findings demonstrated transverse myelitis, based on the DRM diagnostic criteria, the diagnosis of delayed radiation myelitis was reached. Therefore, methylprednisolone pulse therapy was initiated, resulting in the complete resolution of her neurological symptoms. However, on her follow-up examination, although she did not have new neurological complications, magnetic resonance imaging (MRI) demonstrated a residual enhancement in the thoracic spinal cord area. Hence, due to the possibility of myelitis progression and spinal cord atrophy, intravenous immune globulin (IVIG) was administered, resulting in the resolution of lesion enhancement. Considering this outcome and the immunomodulatory properties of IVIG, it could be regarded as a potential therapeutic option in the case of DRM activity.

Familial Mediterranean Fever and Transverse Myelitis: A Causal Relation?

Familial Mediterranean fever (FMF) is a rare autoinflammatory disorder characterized mainly by recurrent self-limited episodes of fever and polyserositis. FMF-related neurologic complication is an old debate, and the correlation between FMF and demyelinating disorders has been a matter of dispute for a long time. Few reports demonstrated a relationship between FMF and multiple sclerosis; however, the existence of a causal relationship between FMF and demyelinating disorders is still a puzzle. This report presents the first case of transverse myelitis following FMF attacks in which neurologic manifestations were resolved using colchicine treatment. Due to relapses of FMF, which were accompanied by transverse myelitis, rituximab was administered, which resulted in stabilizing disease activity. Accordingly, in the case of colchicine-resistant FMF and FMF-related demyelinating conditions, rituximab could be considered as a potential therapeutic option to alleviate both polyserositis and demyelinating manifestations.

Working memory dysfunction differs between secondary progressive and relapsing multiple sclerosis: Effects of clinical phenotype, age, disease duration, and disability.

BACKGROUND: Cognitive dysfunction is relatively common in patients with multiple sclerosis (MS). Although it occurs in all stages and all phenotypes of MS, it is more prevalent in secondary progressive MS (SPMS) compared to relapsing MS (RMS). It is unclear whether the higher frequency of cognitive impairment in SPMS is linked to the progressive phenotype or other clinical factors. In this study, we compared working memory in patients with RMS, SPMS, and healthy subjects. We also investigated the effects of age, disease duration, and disability on working memory performance. METHODS: This case-control study enrolled 134 MS patients, 69 patients were diagnosed with RMS and 65 patients with SPMS, and 77 healthy control subjects. We designed two working memory tasks with different sets of stimuli (face vs. checkerboard) and different instructions (same or different vs. which one is the same). RESULTS: Accuracy was significantly more impaired in SPMS patients than in RMS patients and both groups were worse than healthy subjects. This finding was similar between both tasks. Age and overall cognitive functions (measured with MoCA) also affected accuracy, but disease duration and disability only affected accuracy in working memory task with checkerboard stimuli. CONCLUSION: MS patients are impaired in keeping the information in the visual working memory for a few seconds. Progressive phenotype significantly affected working memory accuracy, and this effect did not explain out with other demographic or clinical factors. Future studies are needed to reveal underlying mechanisms of working memory dysfunction in SPMS and working memory dysfunction as a biomarker of disease progression.

Fulminant neuromyelitis optica spectrum disorder (NMOSD) following COVID-19 vaccination: A need for reconsideration?

During the coronavirus disease 2019 (COVID-19) pandemic, mass vaccination was a beneficial strategy in many countries. Nevertheless, reports of serious complications such as postvaccination neuromyelitis optica spectrum disorder (NMOSD) raised concerns about the safety of vaccines. Anamnart and colleagues explained postvaccination NMOSD following different vaccines, including COVID-19. To emphasize the message of this article, in this letter, we present a unique case of postvaccination NMOSD with a fulminant and fatal course, which may show a plausible relationship between COVID-19 vaccination and triggering anti-aquaporin-4 antibody (AQP4-Ab).

Abrupt bilateral blindness as a rare post-acute demyelinating consequence of COVID-19.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) could prompt various neurological complications. Abrupt visual disturbance was reported as a rare severe manifestation of post-coronavirus disease 2019 (COVID-19). Autoimmune conditions were assumed to have an undeniable role in creation of such circumstances. This report presents a 69-year-old woman with sudden bilateral blindness three weeks after recovering from a SARS-CoV-2 infection. Demyelination due to COVID-19-related autoimmune disorder of the central nervous system (CRAD-C) was considered to be the etiology of her bilateral blindness. Due to her progressive demyelination, immunosuppressive treatments were administered, which resulted in stabilizing post-COVID-19 demyelinating lesions. Accordingly, in the case of COVID-19-related neurological deficits, especially the acute and progressive symptoms, there should be great consideration of autoimmune response to prevent serious complications; hence early diagnosis, treatment, and long-term assessment of patients are necessitated.

Olfactory receptors contribute to progression of kidney fibrosis.

Olfactory receptors (ORs) which are mainly known as odor-sensors in the olfactory epithelium are shown to be expressed in several non-sensory tissues. Despite the specified role of some of these receptors in normal physiology of the kidney, little is known about their potential effect in renal disorders. In this study, using the holistic view of systems biology, it was determined that ORs are significantly changed during the progression of kidney fibrosis. For further validation, common differentially expressed ORs resulted from reanalysis of two time-course microarray datasets were selected for experimental evaluation in a validated murine model of unilateral ureteral obstruction (UUO). Transcriptional analysis by real-time quantitative polymerase chain reaction demonstrated considerable changes in the expression pattern of Olfr433, Olfr129, Olfr1393, Olfr161, and Olfr622 during the progression of kidney fibrosis. For localization of these ORs, single-cell RNA-sequencing datasets of normal and UUO mice were reanalyzed. Results showed that Olfr433 is highly expressed in macrophages in day-2 and 7 post-injury in UUO mice and not in normal subgroups. Besides, like previous findings, Olfr1393 was shown to be expressed prominently in the proximal tubular cells of the kidney. In conclusion, our combinatorial temporal approach to the underlying mechanisms of chronic kidney disease highlighted the potential role of ORs in progression of fibrosis. The expression of Olfr433 in the macrophages provides some clue about its relation to molecular mechanisms promoted in the fibrotic kidney. The proposed ORs in this study could be the subject of further functional assessments in the future.