Disrupting optimal decision making in visual foraging: The impact of search experience.

This study introduces the diet-choice problem in foraging as a framework to investigate search and decision making in an uncertain environment. Using a mathematical model based on signal detection-based optimal foraging theory and conducting behavioral experiments, we examined whether the choice of uncertain options in a visual foraging task followed the optimal strategy. In addition, we explored whether search history affects behavior by changing the environment in a stepwise manner. We used a visual foraging task in which participants searched for visual stimuli and selected them using mouse clicks. To introduce uncertainty, the stimuli were designed in a way that they could not be completely discriminated by visual inspection. The study consisted of four sessions, during which the ratio of the number of gains to loss stimuli in Experiment 1 and the magnitude of loss in Experiment 2 were varied in a stepwise manner. Although search strategies can adapt to environmental changes, this adjustment is not always optimal. Specifically, although both the rising and falling groups experienced the same environment, their performance differed depending on the order in which participants experienced changing environments. Search strategy can be adjusted in the presence of environmental uncertainty, but it deviates from the optimal strategy due to the influence of the search history in the experienced environment. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

The influence of blocking on feature learning and optimal decision in the visual foraging task.

Foraging refers to behavior that exploits the current environment for resources and induces exploration for a better environment. Visual foraging tasks have been used to study human behavior during visual searches. Participants searched for target stimuli among the distractors and either acquired or lost points when they clicked on a target or distractor. In the current study, we investigated the influence of blocking feature learning in visual foraging. For this purpose, we divided participants into control and blocking groups. The blocking group completed three phases: in the first phase, stimulus colors predicted rewards; in the second phase, stimulus color and orientation predicted rewards; in the third phase, only stimulus orientation predicted rewards. The control group completed either the second and third phases (Experiments 1 and 2) or all three phases (Experiment 3) with different reward combinations: color in Phase 1, color and orientation in Phase 2, and orientation in Phase 3. When the learning of a stimulus feature was blocked, the participants made less accurate responses. This suggests that the learning of task-relevant information was disturbed, and the blocked feature was not selected to after blocking. Additional analyses showed that the performance deviated slightly from the optimal performance; however, the extent of the deviation was not affected by blocking, implying that two distinct decision-making processes were involved in visual foraging. Our findings highlight the impact of blocking feature learning on visual foraging performance and reveal its distinct influence on multiple decision-making processes in this task. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Predictors of a non-response to prophylactic indomethacin for patent ductus arteriosus in preterm infants.

BACKGROUND: Preterm infants are recommended for prophylactic indomethacin (PIND) to promote closure of patent ductus arteriosus (PDA) and reduce morbidity and mortality. This study investigated the predictive factors of a non-response to PIND for PDA in preterm-birth infants. METHODS: Consecutive preterm-birth infants (gestational age: < 28 weeks) who received PIND between 2009 and 2019 were retrospectively enrolled. Seventy-six eligible participants were classified as PIND responders (N = 42) or non-responders (N = 34). Information on potential confounders in maternal obstetric and perinatal data were collected from medical records. Multiple logistic regression analysis was carried out to identify the prognostic factors of a PIND response in preterm-birth infants. RESULTS: The prevalence of intrauterine infection and multiple births was significantly different between responders and non-responders to PIND (intrauterine infection: 2 [4.8%] vs. 8 [23.5%], P = 0.036; twins: 3 [7.1%] vs. 9 [ 26.5%], P = 0.029, respectively). In multivariate logistic regression analysis after adjustment for multiple births, intrauterine infection was a significant and independent predictive factor of a non-response to PIND (odds ratio [OR] 5.54, 95% confidence interval [CI] 1.05-29.2, P = 0.044). A remarkable association was also noted for multiple births with a non-response to PIND (OR 4.22, 95% CI 0.99-17.8, P = 0.050). CONCLUSIONS: Intrauterine infection and multiple births were identified as potential risk factors of a non-response to PIND for PDA in preterm infants.

Liquid Enteral Nutrients Alter the Pharmacokinetics of Orally Administered Carbamazepine in Rats.

The interaction between enteral nutrients (ENs) and drugs co-administered through a nasogastric (NG) tube reportedly affects the absorption and resultant plasma concentrations of the respective drugs. However, the gastrointestinal absorption of carbamazepine (CBZ), an antiepileptic drug, co-administered with liquid ENs through an NG tube has not been clarified. In this study, we measured the recovery rate (%) of CBZ (Tegretol® powder) passed through an NG tube when co-administered with distilled water or ENs (F2α®, Racol® NF, Ensure Liquid®, and Renalen® LP) of different compositions, frequently used in Japan. We also measured the plasma CBZ level in 26 rats after oral co-administration of CBZ with liquid ENs. The CBZ recovery rate was close to 100% in rats of all EN groups after passage through the NG tube. Furthermore, CBZ area under the plasma concentration-time curve from time zero to 9 h (AUC0→9h) of the Ensure liquid® group decreased compared with that of control group (P < 0.05) and Renalen® LP group (P < 0.01). However, the AUC0→9h of CBZ remained unchanged when co-administered with Ensure liquid® 2 h after initial CBZ administration. In conclusion, the co-administration of CBZ with Ensure Liquid® caused a reduction in the absorption of CBZ from the gastrointestinal tract, without adsorption on the NG tube. The administration of Ensure Liquid® 2 h after CBZ is a way to prevent a decrease in plasma CBZ concentration. Our findings suggest that carefully monitoring the plasma levels of CBZ is necessary in co-administation with Ensure liquid® to prevent the unintended effects of the interaction between CBZ and liquid EN.

Heart rate variability in the course of chemotherapy and haematopoietic stem cell transplantation for peadiatric patients with haematological malignancies.

BACKGROUND: High-dose chemotherapy and haematopoietic stem cell transplantation are essential for patients with paediatric haematologic diseases, although cardiotoxicity remains a concern. Heart rate variability analysis can evaluate autonomic nervous function interactions with cardiac function. OBJECTIVE: This study aimed to characterise heart rate variability differences between patients undergoing chemotherapy and controls, and the effects of haematopoietic stem cell transplantation on the autonomic nervous system in patients with haematological malignancies. METHODS: Nineteen patients (11 male, median age: 11.6 years) who received conventional chemotherapy followed by transplantation and 19 non-transplant patients (10 male, median age: 11.5 years) receiving chemotherapy only between 2006 and 2018 for haematological malignancies were retrospectively enrolled. Data from 24-hour Holter monitoring were recorded after chemotherapy and before and after transplantation. Heart rate variability was analysed in patients and 32 matched normal controls. RESULTS: There were significant differences between patients and normal controls in all heart rate variability analysis parameters apart from coefficient of variation of RR interval and standard deviation of the average normal RR interval for all 5-minute segments during sleeping. There was a significant difference in the cumulative anthracycline dose and heart rate variability during sleep between the non-transplant and pre-transplant groups. We observed no remarkable differences in time-domain analysis parameters between before and after transplantation, although the low-frequency component of power-spectrum analysis during awake hours was significantly decreased after transplantation. CONCLUSION: Conventional chemotherapy for paediatric haematologic diseases may be a risk factor for autonomic dysfunction. Further declines in heart rate variability after transplantation appear minor.

Contextual cueing facilitation arises early in the time course of visual search: An investigation with the `speed-accuracy tradeoff task.

Visual search is expedited in a spatial context encountered repeatedly. A much-debated question is how early the facilitation by contextual memory arises. The current study examined the possibility of the facilitation of early attentional processing by constructing a descriptive model of the time course of visual search and its facilitation by contextual cueing. Participants in this experiment engaged in a speed-accuracy tradeoff (SAT) task after learning the spatial contexts in a standard visual search task in which they searched for a rotated T target among Ls. In the SAT task, they were required to search for the target and respond immediately when a sound probe was presented, even if they did not find or identify the target when the inter-stimulus interval between the search display and the probe varied from 40 ms to 2,000 ms. Participants completed two blocks of the SAT task, in which they searched in learned and new contexts. The results of the SAT procedure showed that responses were more accurate in repeated contexts than in new contexts, even when only a brief period of time elapsed after presenting the search display (> 90 ms). We conducted an analysis of the time course of contextual-cueing effects with Bayesian hierarchical modeling, which demonstrated that the rate of increase in accuracy was higher for the repeated than for the new contexts. These findings suggest that early attentional processing is enhanced by learning the contexts, and this enhancement arises very early in the time course of the visual search.

Possible involvement of aminopeptidase A in hypertension and renal damage in Dahl salt-sensitive rats.

BACKGROUND: Although aminopeptidase A (APA), which is abundant in the kidneys, is responsible for metabolizing angiotensin II (Ang II), its association with salt sensitivity remains uncertain. We aimed to clarify the involvement of APA in salt-induced hypertension and renal damage. METHODS: Male Dahl salt-sensitive (DS) and Dahl salt-resistant (DR) rats were fed low-salt (0.3%) or high-salt diet (8%) from 6 weeks of age for 12 weeks. Tail-cuff-measured blood pressure (BP), renal APA activity, renal Ang II levels, histologic renal damage, and APA immunoreactivity were periodically examined. RESULTS: Systolic BP progressively increased only in DS rats given the high-salt diet (DS-8% rats). The DR-8% rats had approximately 3-fold higher renal APA activity than the rats given the low-salt diet (DR-0.3% rats) during the maintenance on the high-salt diet. However, although DS-8% rats also had 2.5-fold higher renal APA activity than DS-0.3% rats at 10 weeks, continuing the high-salt diet afterward suppressed the activity in DS-8% rats below the levels observed in DS-0.3% rats. High-salt diet reduced renal Ang II levels by 30% in DR rats, whereas it showed a small and nonsignificant decrease in DS rats. The number of injured glomeruli was markedly elevated in DS-8% rats after 10 weeks. The APA immunostaining in DS-8% rats was enhanced in glomeruli displaying mild damage, diminished in the severely injured glomeruli, and absent in lesions with hyalinization. CONCLUSIONS: High-salt diet in DS rats increased renal APA activity, although renal injury remained mild, but then reduced it along with the progression of glomerulosclerosis, suggesting that reduced APA activity may be involved in the deterioration of salt-induced hypertension and renal injury.

Expression of glucose transporter 4 in the human pancreatic islet of Langerhans.

Glucose transporter 4 (GLUT4) is the main insulin-responsive glucose transporter in skeletal muscle and adipose tissue of human and rodent, and is translocated to the plasma membrane in response to insulin. GLUT2 is well known as the main glucose transporter in pancreatic islets and could highly regulate glucose-stimulated insulin secretion by B-cells as a glucose sensor. We confirmed the presence of GLUT4 mRNA and GLUT4 protein in pancreas in the human. Indirect immunohistochemistry showed that the pancreatic islets of human and rat were conspicuously labeled by anti-GLUT4 antibody. The presence of placental leucine aminopeptidase (P-LAP), a homologue of insulin-regulated aminopeptidase (IRAP), was also shown in the human pancreatic islet. IRAP/P-LAP is thought to be involved in glucose metabolism. This study provides the first evidence that GLUT4 is present in human and rat pancreatic islets and may suggest its specific role in glucose homeostasis in conjunction with IRAP/P-LAP.

Tissue distribution of placental leucine aminopeptidase/oxytocinase during mouse pregnancy.

Placental leucine aminopeptidase (P-LAP), also called oxytocinase, is an enzyme responsible for hydrolyzing oxytocin. This enzyme is identical to cystine aminopeptidase. We examined the tissue distribution of P-LAP in normal adult mice and also in mothers and fetuses during mouse pregnancy using immunohistochemical (IHC) analysis. P-LAP-immunoreactive protein was expressed in various organs in a cell- and gestational stage-dependent manner. In the kidney, P-LAP was located in distal and collecting tubules but not in proximal tubules. The islet of Langerhans in the maternal pancreas stained positively for P-LAP in the periphery in early gestation. This staining pattern changed so that both the periphery and inner cells were positive during mid-gestation and finally only inner cells were positive in late gestation. Among the hematopoietic cells in the fetal liver, only megakaryocytes showed strong expression of P-LAP. The staining intensity increased with gestation on the apical surface of trophoblasts in the placental labyrinth. These data demonstrate that P-LAP is present in a variety of tissues, and its presence is affected by pregnancy and fetal development. Therefore, P-LAP may play a significant role in various physiological processes in non-pregnant, pregnant, and fetal mice.

Hypertension and angiotensin II hypersensitivity in aminopeptidase A-deficient mice.

Local concentrations of the vasopressor peptide, angiotensin II (AngII), depend upon the balance between synthesis and degradation. Previous studies of blood pressure (BP) regulation have focused primarily on the generation of AngII and its receptors, and less attention has been devoted to angiotensin degradation. Aminopeptidase A (APA, EC 3.4.11.7) is responsible for the N-terminal cleavage of AngII, a hydrolytic event that serves as a rate-limiting step in angiotensin degradation. To evaluate the physiological role of APA, we examined BP homeostasis in APA-deficient mice. We measured basal BP and BP with continuous infusion of AngII in APA mutant mice by tail-cuff method. We also evaluated the development and histology of AngII-targeted organs as well as urine excretion in these mice. Homozygous APA mutant mice were found to have elevated basal systolic BP when compared with heterozygous mutant and wild-type littermate mice. Infusion of AngII led to an enhanced systolic BP response in the APA-deficient mice. Despite the sustained elevation of BP in APA knockout mice, neither their renal and cardiac sizes nor their histological appearances were not different from control mice. Moreover, the volume, osmolality, and electrolyte content of the urine were normal in APA-deficient mice. APA deficiency increased baseline BP and enhanced the hypertensive response to increased levels of AngII. These findings indicate a physiological role for APA in lowering BP and offer novel insight into the mechanisms for developing hypertension.