Prediction error and event segmentation in episodic memory

Organizing the continuous flow of experiences into meaningful events is a crucial prerequisite for episodic memory. Prediction error and event segmentation both play important roles in supporting the genesis of meaningful mnemonic representations of events. We review theoretical contributions discussing the relationship between prediction error and event segmentation, as well as literature on episodic memory related to prediction error and event segmentation. We discuss the extent of overlap of mechanisms underlying memory emergence through prediction error and event segmentation, with a specific focus on attention and working memory. Finally, we identify areas in research that are currently developing and suggest future directions. We provide an overview of mechanisms underlying memory formation through predictions, violations of predictions, and event segmentation.

Can affinity of hemoglobin to oxygen to be a prognostic marker in critically ill COVID-19 patients?

Background

This study's objective is to determine the slope of the hemoglobin oxygen dissociation curve in critically ill patients who have COVID-19 along with blood gas measurements and how mortality might be impacted by this circumstance.

Aim

It has been reported that the hemoglobin oxygen dissociation curve is not different from healthy patients in COVID-19. However, there are insufficient data on the behavior of the curve in patients who require intensive care.

Patients and Methods

This retrospective study was conducted between 01.03.2021 and 01.07.2021 with patients who were followed up due to COVID-19 in adult intensive care unit. P50 and lactate value obtained from in vitro calculated blood gas analysis. The survival status of the patients was recorded.

Results

The mean P50 value at the admission of nonsurvivors was significantly higher than survivors. In correlation analysis, a significant positive correlation was seen between P50, mortality, and lactate level at admission. SpO₂, PaO₂/FiO₂ ratio, and length of stay in intensive care unit were significantly negatively correlated with P50 levels.

Conclusion

A right shift in the hemoglobin oxygen dissociation curve is associated with mortality. Lactate levels were also associated with a right shift. Prospective experimental studies are needed to provide a better understanding of this process.

Not what u expect: Effects of prediction errors on item memory

The characterization of the relationship between predictions and one-shot episodic encoding poses an important challenge for memory research. On the one hand, events that are compatible with our previous knowledge are thought to be remembered better than incompatible ones. On the other hand, unexpected situations, by virtue of their novelty, are known to cause enhanced learning. Several theoretical accounts try to solve this apparent paradox by conceptualizing prediction error (PE) as a continuum ranging from low PE (for expectation-matching events) to high PE (for expectation-mismatching ones). Under such a framework, the relationship between PE and memory encoding would be described by a U-shape function with higher memory performance for extreme levels of PE and lower memory for middle levels of PE. In this study, we tested the framework by using a gradual manipulation of the strength of association between scenes and objects to render different levels of PE and then tested for item memory of the (mis)matching events. In two experiments, in contrast to what was anticipated, recognition memory for object identity followed an inverted U-shape as a function of PE, with higher performance for intermediate levels of PE. Furthermore, in two additional experiments, we showed the relevance of explicit predictions at encoding to reveal such an inverted U pattern, thus providing the boundary conditions of the effect. We discussed our findings in light of existing literature relating PE and episodic memory, pointing out the potential roles of uncertainty in the environment, and the importance of the cognitive operations underlying encoding tasks. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Successful treatment of type III atresia ani and rectovaginal fistula in a kitten

A six-weeks-old, female kitten presented with dehydration, depression, atresia ani and a discharge of watery feces from the vulvar opening. On radiographic examination, the blind-end of the rectum was determined to be >1 cm cranial from the anal dimple, classifying it as type III atresia ani. Atresia ani combined with a rectovaginal fistula is an uncommon congenital defect of the terminal rectum and anus that can occur in kittens. After supportive medical treatment for three days, the patient was strong enough for surgical correction. The distal rectal pouch was connected to the unperforated anus and the rectovaginal fistula was closed. The kitten recovered uneventfully and was able to defecate normally at 38 weeks follow-up. In this case report, the importance of early surgical correction to avoid potential life-threatening complications from this congenital abnormality is demonstrated.

Comparing electrophysiological correlates of judgment of learning and feeling of knowing during face-name recognition

We investigated the event-related potential (ERP) correlates of two metacognitive judgments, namely judgment of learning (JOL) and feeling of knowing (FOK) induced by a face-name recognition (FNR) task in 60 participants. The FNR produced N170 and P100 components at posterior, and an N100 component at anterior electrodes. Posterior P200, anterior N200 components were recorded during JOL and FOK judgments. Our data showed that ERP correlates of JOL and FOK emerge as rapidly as 200 ms following stimulus presentation, and these two metacognitive judgments are based on both perceptual fluency and conflict processes. However, these ERP components affected by the degree of JOL and FOK judgments. Thus, we concluded that even though JOL and FOK judgments produced similar ERP wave forms temporal dynamics of these two judgments are different. Also, our results support the hypothesis that metacognitive judgments are linked to distributed neural substrates rather than strictly to frontal lobe function.

Neurobiological basis of feeling of knowing in episodic memory

Feeling of knowing (FOK) is a metacognitive process which allows individuals to predict the likelihood that they will be able to remember, in the future, information which they currently cannot recall. Although FOK provides evidence for the mechanisms of metacognitive systems, the neurobiological basis of FOK is still unclear. We investigated the neural correlates of FOK induced by an episodic memory task in 77 younger adult participants. Data were gathered using event-related potentials (ERPs). ERP components during high, low, extremely high and extremely low FOK judgments were analyzed. Stimulus-locked ERP analyses indicated that FOK judgment was associated with greater positivity for P200 component at frontal, central, and parietal electrode zones and greater negativity for the N200 component at parietal electrode zones. Furthermore, results revealed that amplitude of the ERP components for FOK judgments were affected by the level of FOK judgment. Results suggest that ERP components of FOK judgment observed within a 200 ms time window support the perceptual fluency-based model.

The effect of gadolinium-based contrast agents on rat testis

Previous studies have reported that repeated administrations of linear gadolinium-based contrast agents lead to their accumulation in the brain and other tissues in individuals with normal renal functions. The purpose of this prospective animal study was to investigate the effect of multiple administrations of macrocyclic ionic (gadoteric acid) and linear nonionic (gadodiamide) gadolinium-based contrast agents (GBCAs) on rat testis tissue and to compare these molecules in terms of tissue damage. Thirty-two male Sprague-Dawley rats were kept without drugs for 5 weeks after administration of 0.1 mmol mg^-1 kg^-1 (0.2 ml/kg) gadodiamide and gadoteric acid for 4 days over 5 weeks. Biochemical, histopathological and immunohistochemical changes in testis tissue were evaluated at the end of 10 weeks. When used in repeated clinical doses, gadolinium was observed to increase apoptosis in the Leydig cells of the rat testis, and to increase serum Ca⁺² levels and reduce testosterone levels (p < .05). Although the difference was not statistically significant, a greater loss of spermatozoa and immature germinal cell accumulation were observed in the seminiferous tubule lumen in the GBCA groups compared with the control and saline groups (p > .05). Both linear and macrocyclic contrast agents have toxic effects on testis tissue, irrespective of the type of drug.

Acute effects of static stretching on isokinetic thigh strength on modern dancers

AIM

The aim of this study was to examine the acute effects of static stretching in dominant leg flexor muscle groups on concentric isokinetic leg extension and flexion peak torque (PT), peak torque % body weight (PT%BW) and total work (TW) at 60, 180 and 300 °.s-1 in stretched and non-stretched limbs of modern dancers.

METHODS

Twenty-six trained modern dancers volunteered in this study. On the first measurement, isokinetic tests were performed on dominant and non-dominant legs. On the second measurement, the dominant leg flexors were stretched using 3 unassisted and 1 assisted static stretching exercises (each 4x15 seconds; 10-second rest). After the stretching, isokinetic tests were repeated on both legs.

RESULTS

The results indicated a positive increase in strength in the stretched (PT%BW, TW) and non-stretched (PT, PT%BW, TW) limbs in flexion at 180°s-1 (P<0.05). We observed a positive increase (P<0.05) in the stretched limb (180 and 300°.s-1, TW; 300°.s-1, PT%BW) in extension whereas an acute decrease (P<0.05) was observed in both legs (60˚.s-1, PT and PT%BW).

CONCLUSION

Our findings indicated a possible positive effect of static stretching at high angular velocities on the strength production of isokinetic contraction in stretched and non-stretched muscles. However, due to its negative effect on the extensor muscle groups, we think using static stretching is required attention before maximal strength exercises.

[Dynamic left ventricular outflow tract obstruction in pulmonary embolism]

Left ventricular hypertrophy, dehydration, sepsis, vasodilatation, excessive sympathetic stimulation, pericardial tamponade and surgical treatment of the atrioventricular valve are known causes of left ventricular outflow tract (LVOT) obstruction. We report the rare case of a patient who developed dynamic LVOT obstruction as a complication of acute pulmonary embolism.

Effects of exercise training on mobilization and functional activity of blood-derived progenitor cells in patients with acute myocardial infarction

BACKGROUND

The aim of the present study was to determine whether regular exercise training (ET) is effective at promoting the mobilization of CPCs and improving their functional activity in patients with recently acquired myocardial infarction (STEMI). Regular physical training has been shown to improve myocardial perfusion and cardiovascular function. This may be related in part to a mobilization of bone marrow-derived circulating progenitor cells (CPCs) as well as an enhanced vascularisation.

METHODS

37 patients with STEMI were randomly assigned to an ET group or a non-ET group (controls). Two weeks after STEMI, three weeks after regular ET and three months after ET, BNP levels, exercise echocardiography and exercise spiroergometry were evaluated. The number of CD34+/CD45+ and CD133+/CD45+ CPCs was measured by flow cytometry analysis. The migration capacity of the CPCs was determined with a boyden chamber and the clonogenic capacity by CFU-assay.

RESULTS

In the ET-group the number and migration capacity of CPCs increased significantly after regular exercise training. The BNP level decreased significantly from 121 +/- 94 to 75 +/- 47 pg/ml (p<0.001) after the ET period, the left ventricular ejection fraction raised in parallel at peak exercise, and the cardiorespiratory condition improved as demonstrated by an increase of VO2max (from 1641 +/- 522 to 1842 +/- 724 ml/min, p<0.02). These three effects persist till three months after the ET period.

CONCLUSIONS

Regular physical activity appears to predispose the mobilization and enhanced functional activity of CPCs, a phenomenon which might lead to an improved cardiac function in patients with recently acquired acute myocardial infarction.

Bloodstream infections in a medical-surgical intensive care unit: incidence, aetiology, antimicrobial resistance patterns of Gram-positive and Gram-negative bacteria

In the present study, the incidence and antimicrobial resistance patterns of the microorganisms that caused bloodstream infections (BSIs) in a medical-surgical intensive care unit during the years 2005-2007 were determined. The mean BSI incidence density was 6.56 per 1000 patient-days. The incidence density increased linearly during the study period (from 3.57 to 9.60 per 1000 patient-days). Staphylococcus aureus was most frequently isolated (47.3%), followed by Enterococcus spp. (10.8%) and Candida spp. (10.1%). There was a high rate of resistance to several of the prescribed antimicrobials among the bacteria isolated from patients with BSIs.