Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 41
Filtrar
1.
PNAS Nexus ; 3(7): pgae232, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38948017

RESUMO

When people make choices, the items they consider are often embedded in a context (of other items). How this context affects the valuation of the specific item is an important question. High-value context might make items appear less attractive because of contrast-the tendency to normalize perception of an object relative to its background-or more attractive because of assimilation-the tendency to group objects together. Alternatively, a high-value context might increase prior expectations about the item's value. Here, we investigated these possibilities. We examined how unavailable context items affect choices between two target items, as well as the willingness-to-pay for single targets. Participants viewed sets of three items for several seconds before the target(s) were highlighted. In both tasks, we found a significant assimilation-like effect where participants were more likely to choose or place a higher value on a target when it was surrounded by higher-value context. However, these context effects were only significant for participants' fastest choices. Using variants of a drift-diffusion model, we established that the unavailable context shifted participants' prior expectations towards the average values of the sets but had an inconclusive effect on their evaluations of the targets during the decision (i.e. drift rates). In summary, we find that people use context to inform their initial valuations. This can improve efficiency by allowing people to get a head start on their decision. However, it also means that the valuation of an item can change depending on the context.

2.
medRxiv ; 2024 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-38343837

RESUMO

Background: Multisystem inflammatory syndrome in children (MIS-C) is a severe post-acute sequela of SARS-CoV-2 infection. The highly diverse clinical features of MIS-C necessities characterizing its features by subphenotypes for improved recognition and treatment. However, jointly identifying subphenotypes in multi-site settings can be challenging. We propose a distributed multi-site latent class analysis (dMLCA) approach to jointly learn MIS-C subphenotypes using data across multiple institutions. Methods: We used data from the electronic health records (EHR) systems across nine U.S. children's hospitals. Among the 3,549,894 patients, we extracted 864 patients < 21 years of age who had received a diagnosis of MIS-C during an inpatient stay or up to one day before admission. Using MIS-C conditions, laboratory results, and procedure information as input features for the patients, we applied our dMLCA algorithm and identified three MIS-C subphenotypes. As validation, we characterized and compared more granular features across subphenotypes. To evaluate the specificity of the identified subphenotypes, we further compared them with the general subphenotypes identified in the COVID-19 infected patients. Findings: Subphenotype 1 (46.1%) represents patients with a mild manifestation of MIS-C not requiring intensive care, with minimal cardiac involvement. Subphenotype 2 (25.3%) is associated with a high risk of shock, cardiac and renal involvement, and an intermediate risk of respiratory symptoms. Subphenotype 3 (28.6%) represents patients requiring intensive care, with a high risk of shock and cardiac involvement, accompanied by a high risk of >4 organ system being impacted. Importantly, for hospital-specific clinical decision-making, our algorithm also revealed a substantial heterogeneity in relative proportions of these three subtypes across hospitals. Properly accounting for such heterogeneity can lead to accurate characterization of the subphenotypes at the patient-level. Interpretation: Our identified three MIS-C subphenotypes have profound implications for personalized treatment strategies, potentially influencing clinical outcomes. Further, the proposed algorithm facilitates federated subphenotyping while accounting for the heterogeneity across hospitals.

3.
J Pediatric Infect Dis Soc ; 12(3): 159-162, 2023 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-36786218

RESUMO

Using electronic health record data combined with primary chart review, we identified seven children across nine participant pediatric medical centers with a diagnosis of Multisystem Inflammatory Syndrome in Children (MIS-C) managed exclusively as outpatients. These findings should raise awareness of mild presentations of MIS-C and the option of outpatient management.


Assuntos
COVID-19 , Pacientes Ambulatoriais , Humanos , Criança , Estudos de Coortes , Síndrome de Resposta Inflamatória Sistêmica/diagnóstico , Síndrome de Resposta Inflamatória Sistêmica/terapia
4.
Front Genet ; 13: 936151, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36406122

RESUMO

Symptoms of normal pressure hydrocephalus (NPH) and Alzheimer's disease (AD) are somewhat similar, and it is common to misdiagnose these two conditions. Although there are fluid markers detectable in humans with NPH and AD, determining which biomarker is optimal in representing genetic characteristics consistent throughout species is poorly understood. Here, we hypothesize that NPH can be differentiated from AD with mRNA biomarkers of unvaried proximity to telomeres. We examined human caudate nucleus tissue samples for the expression of transient receptor potential cation channel subfamily V member 4 (TRPV4) and amyloid precursor protein (APP). Using the genome data viewer, we analyzed the mutability of TRPV4 and other genes in mice, rats, and humans through matching nucleotides of six genes of interest and one house keeping gene with two factors associated with high mutation rate: 1) proximity to telomeres or 2) high adenine and thymine (A + T) content. We found that TRPV4 and microtubule associated protein tau (MAPT) mRNA were elevated in NPH. In AD, mRNA expression of TRPV4 was unaltered unlike APP and other genes. In mice, rats, and humans, the nucleotide size of TRPV4 did not vary, while in other genes, the sizes were inconsistent. Proximity to telomeres in TRPV4 was <50 Mb across species. Our analyses reveal that TRPV4 gene size and mutability are conserved across three species, suggesting that TRPV4 can be a potential link in the pathophysiology of chronic hydrocephalus in aged humans (>65 years) and laboratory rodents at comparable ages.

5.
J Emerg Med ; 63(3): 348-354, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-36115745

RESUMO

BACKGROUND: Limited compression bedside ultrasonography (LCUS) including two-point, three-point, and extended compression examinations have become increasingly popular among emergency physicians to assess for lower extremity deep venous thrombosis (DVT). OBJECTIVE: Our objective in this study was to determine the prevalence and distribution of lower extremity DVT in sites identified by complete duplex ultrasonography (CDUS) that may potentially be missed using limited compression ultrasonography techniques. METHODS: This was a retrospective, multicenter study conducted at 12 hospitals within the Northwell Health system over a span of 4 years. Study participants (emergency department patients) underwent CDUS to assess for possible DVT. Images were reviewed and interpreted by radiologists and vascular surgeons at each of the participating institutions. RESULTS: A total of 42,487 CDUS examinations were performed, of which 3383 were positive for DVT. DVTs were deemed to be acute in 2664 (79%) and chronic in the remaining 21% on the basis of comparison with previous studies and appearance of the vein. Of the acute DVTs, 136 (5.1%) were confined to the common femoral vein, 116 (4.4%) to the femoral vein, 8 (0.3%) to deep femoral vein, 213 (8.0%) to popliteal vein, and 934 (35.1) to calf veins alone. CONCLUSIONS: In our study, a significant number of DVTs were identified in sites that may have been potentially missed on LCUS examinations, thereby supporting the use of complete duplex ultrasonography when available.


Assuntos
Veia Poplítea , Trombose Venosa , Humanos , Estudos Retrospectivos , Veia Poplítea/diagnóstico por imagem , Trombose Venosa/diagnóstico por imagem , Trombose Venosa/epidemiologia , Ultrassonografia/métodos , Extremidade Inferior/irrigação sanguínea
6.
JAMA Pediatr ; 176(10): 1000-1009, 2022 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-35994282

RESUMO

Importance: The postacute sequelae of SARS-CoV-2 infection (PASC) has emerged as a long-term complication in adults, but current understanding of the clinical presentation of PASC in children is limited. Objective: To identify diagnosed symptoms, diagnosed health conditions, and medications associated with PASC in children. Design, Setting and Participants: This retrospective cohort study used electronic health records from 9 US children's hospitals for individuals younger than 21 years who underwent antigen or reverse transcriptase-polymerase chain reaction (RT-PCR) testing for SARS-CoV-2 between March 1, 2020, and October 31, 2021, and had at least 1 encounter in the 3 years before testing. Exposures: SARS-CoV-2 positivity by viral test (antigen or RT-PCR). Main Outcomes and Measures: Syndromic (symptoms), systemic (conditions), and medication PASC features were identified in the 28 to 179 days following the initial test date. Adjusted hazard ratios (aHRs) were obtained for 151 clinically predicted PASC features by contrasting viral test-positive groups with viral test-negative groups using proportional hazards models, adjusting for site, age, sex, testing location, race and ethnicity, and time period of cohort entrance. The incidence proportion for any syndromic, systemic, or medication PASC feature was estimated in the 2 groups to obtain a burden of PASC estimate. Results: Among 659 286 children in the study sample, 348 091 (52.8%) were male, and the mean (SD) age was 8.1 (5.7) years. A total of 59 893 (9.1%) tested positive by viral test for SARS-CoV-2, and 599 393 (90.9%) tested negative. Most were tested in outpatient testing facility settings (322 813 [50.3%]) or office settings (162 138 [24.6%]). The most common syndromic, systemic, and medication features were loss of taste or smell (aHR, 1.96; 95% CI, 1.16-3.32), myocarditis (aHR, 3.10; 95% CI, 1.94-4.96), and cough and cold preparations (aHR, 1.52; 95% CI, 1.18-1.96), respectively. The incidence of at least 1 systemic, syndromic, or medication feature of PASC was 41.9% (95% CI, 41.4-42.4) among viral test-positive children vs 38.2% (95% CI, 38.1-38.4) among viral test-negative children, with an incidence proportion difference of 3.7% (95% CI, 3.2-4.2). A higher strength of association for PASC was identified in those cared for in the intensive care unit during the acute illness phase, children younger than 5 years, and individuals with complex chronic conditions. Conclusions and Relevance: In this large-scale, exploratory study, the burden of pediatric PASC that presented to health systems was low. Myocarditis was the most commonly diagnosed PASC-associated condition. Acute illness severity, young age, and comorbid complex chronic disease increased the risk of PASC.


Assuntos
COVID-19 , Miocardite , Adolescente , COVID-19/complicações , COVID-19/diagnóstico , COVID-19/epidemiologia , Criança , Feminino , Humanos , Masculino , Estudos Retrospectivos , SARS-CoV-2 , Adulto Jovem
7.
medRxiv ; 2022 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-35665016

RESUMO

Importance: The post-acute sequelae of SARS-CoV-2 (PASC) has emerged as a long-term complication in adults, but current understanding of the clinical presentation of PASC in children is limited. Objective: To identify diagnosed symptoms, diagnosed health conditions and medications associated with PASC in children. Design Setting and Participants: Retrospective cohort study using electronic health records from 9 US children's hospitals for individuals <21 years-old who underwent reverse transcriptase polymerase chain reaction (RT-PCR) testing for SARS-CoV-2 between March 1, 2020 - October 31, 2021 and had at least 1 encounter in the 3 years before testing. Exposure: SARS-CoV-2 PCR positivity. Main Outcomes and Measures: We identified syndromic (symptoms), systemic (conditions), and medication PASC features in the 28-179 days following the initial test date. Adjusted hazard ratios (aHRs) were obtained for 151 clinically predicted PASC features by contrasting PCR-positive with PCR-negative groups using proportional hazards models, adjusting for site, age, sex, testing location, race/ethnicity, and time-period of cohort entrance. We estimated the incidence proportion for any syndromic, systemic or medication PASC feature in the two groups to obtain a burden of PASC estimate. Results: Among 659,286 children in the study sample, 59,893 (9.1%) tested positive by PCR for SARS-CoV-2. Most were tested in outpatient testing facility (50.3%) or office (24.6%) settings. The most common syndromic, systemic, and medication features were loss of taste or smell (aHR 1.96 [95% CI 1.16-3.32), myocarditis (aHR 3.10 [95% CI 1.94-4.96]), and cough and cold preparations (aHR 1.52 [95% CI 1.18-1.96]). The incidence of at least one systemic/syndromic/medication feature of PASC was 41.9% among PCR-positive children versus 38.2% among PCR-negative children, with an incidence proportion difference of 3.7% (95% CI 3.2-4.2%). A higher strength of association for PASC was identified in those cared for in the ICU during the acute illness phase, children less than 5 years-old, and individuals with complex chronic conditions. Conclusions and Relevance: In this large-scale, exploratory study, the burden of pediatric PASC that presented to health systems was low. Myocarditis was the most commonly diagnosed PASC-associated condition. Acute illness severity, young age, and comorbid complex chronic disease increased the risk of PASC. Key Points: Question: What are the incidence and clinical features of post-acute sequelae of SARS-CoV-2 infection (PASC) in children?Findings: In this retrospective cohort study of 659,286 children tested for SARS-CoV-2 by polymerase chain reaction (PCR), the symptom, condition and medication with the strongest associations with SARS-CoV-2 infection were loss of taste/smell, myocarditis, and cough and cold preparations. The incidence proportion of non-MIS-C related PASC in the PCR-positive group exceeded the PCR-negative group by 3.7% (95% CI 3.2-4.2), with increased rates associated with acute illness severity, young age, and medical complexity.Meaning: PASC in children appears to be uncommon, with features that differ from adults.

8.
Genet Med ; 24(9): 1899-1908, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35616647

RESUMO

PURPOSE: Neurodevelopmental disorders (NDDs), such as intellectual disability (ID) and autism spectrum disorder (ASD), exhibit genetic and phenotypic heterogeneity, making them difficult to differentiate without a molecular diagnosis. The Clinical Genome Resource Intellectual Disability/Autism Gene Curation Expert Panel (GCEP) uses systematic curation to distinguish ID/ASD genes that are appropriate for clinical testing (ie, with substantial evidence supporting their relationship to disease) from those that are not. METHODS: Using the Clinical Genome Resource gene-disease validity curation framework, the ID/Autism GCEP classified genes frequently included on clinical ID/ASD testing panels as Definitive, Strong, Moderate, Limited, Disputed, Refuted, or No Known Disease Relationship. RESULTS: As of September 2021, 156 gene-disease pairs have been evaluated. Although most (75%) were determined to have definitive roles in NDDs, 22 (14%) genes evaluated had either Limited or Disputed evidence. Such genes are currently not recommended for use in clinical testing owing to the limited ability to assess the effect of identified variants. CONCLUSION: Our understanding of gene-disease relationships evolves over time; new relationships are discovered and previously-held conclusions may be questioned. Without periodic re-examination, inaccurate gene-disease claims may be perpetuated. The ID/Autism GCEP will continue to evaluate these claims to improve diagnosis and clinical care for NDDs.


Assuntos
Transtorno do Espectro Autista , Transtorno Autístico , Deficiência Intelectual , Transtornos do Neurodesenvolvimento , Transtorno do Espectro Autista/diagnóstico , Transtorno do Espectro Autista/genética , Transtorno Autístico/diagnóstico , Transtorno Autístico/genética , Humanos , Deficiência Intelectual/diagnóstico , Deficiência Intelectual/genética , Transtornos do Neurodesenvolvimento/genética
9.
J Pediatr Hematol Oncol ; 44(2): e605-e608, 2022 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-34486558

RESUMO

BACKGROUND: Thymic carcinomas are rare aggressive mediastinal tumors with a median survival of 2 years. OBSERVATION: We present a pediatric patient who was diagnosed with metastatic thymic carcinoma and showed continuous improvement of his primary mass and lung metastases with a regimen of cisplatin/docetaxel followed by long-term maintenance therapy with sunitinib for over 5 years. CONCLUSIONS: This report demonstrates a long-term positive treatment effect using chemotherapy followed by sunitinib in an advanced thymic carcinoma. We are not aware of other reports of pediatric patients with metastatic thymic carcinoma treated with sunitinib maintenance who maintained a durable response for this prolonged period of time.


Assuntos
Neoplasias Pulmonares , Timoma , Neoplasias do Timo , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Criança , Cisplatino , Humanos , Neoplasias Pulmonares/tratamento farmacológico , Sunitinibe/uso terapêutico , Timoma/tratamento farmacológico , Neoplasias do Timo/tratamento farmacológico , Neoplasias do Timo/patologia
10.
Front Cell Dev Biol ; 9: 630067, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33816475

RESUMO

Cell fate decisions during development are governed by multi-factorial regulatory mechanisms including chromatin remodeling, DNA methylation, binding of transcription factors to specific loci, RNA transcription and protein synthesis. However, the mechanisms by which such regulatory "dimensions" coordinate cell fate decisions are currently poorly understood. Here we quantified the multi-dimensional molecular changes that occur in mouse embryonic stem cells (mESCs) upon depletion of Estrogen related receptor beta (Esrrb), a key pluripotency regulator. Comparative analyses of expression changes subsequent to depletion of Esrrb or Nanog, indicated that a system of interlocked feed-forward loops involving both factors, plays a central part in regulating the timing of mESC fate decisions. Taken together, our meta-analyses support a hierarchical model in which pluripotency is maintained by an Oct4-Sox2 regulatory module, while the timing of differentiation is regulated by a Nanog-Esrrb module.

12.
Pediatr Radiol ; 49(13): 1781-1787, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31352514

RESUMO

BACKGROUND: Pituitary pars intermedia/Rathke cleft cysts or cyst-like structures are commonly encountered in children undergoing brain magnetic resonance imaging (MRI), especially when examinations include thin-section, high-resolution sequences. OBJECTIVE: To determine the prevalence of pituitary cystic lesions in children at our institution using modern MRI technique, to assess for associated endocrinopathy and to address the need for follow-up. MATERIALS AND METHODS: We retrospectively reviewed 232 consecutive 1.5- and 3-T brain MRIs in children ages 0-18 years (mean: 8.3±5.3 years). We evaluated 3-D volumetric T1 spoiled gradient echo (SPGR) and axial T2-weighted sequences. Pituitary glands were evaluated for the presence, size and signal characteristics of cysts. Cyst volumes were measured in three orthogonal planes. Endocrine abnormalities were documented from the medical record. RESULTS: Pituitary cysts were present in 57.7% of children (n=134), with a mean linear measurement of 3.6±1.17 mm (range: 0.4 to 12.3 mm). The overwhelming majority of cysts were hyopointense on T1-W images (n=121, 90%) and isointense on T2-W images relative to the adenohypophysis (n=106, 79%). T1 hyperintense and T2 hypointense signals were present in a minority, 6.7% and 8%, respectively. Most cysts were occult on post-contrast T1-W images (n=24, 77%). Endocrine abnormalities were present in 2/134 (1.5%) of children with cysts (these were unrelated to the pituitary gland) versus 1/98 (1%) children without cysts (P=0.7). CONCLUSION: More often than not, pituitary cysts/cyst-like structures can be found incidentally in children using modern MRI techniques. Follow-up is not typically required if there are no associated symptoms or excessive size.


Assuntos
Cistos do Sistema Nervoso Central/diagnóstico por imagem , Imageamento Tridimensional , Imageamento por Ressonância Magnética/métodos , Neoplasias Hipofisárias/diagnóstico por imagem , Intensificação de Imagem Radiográfica , Adolescente , Distribuição por Idade , Cistos do Sistema Nervoso Central/epidemiologia , Cistos do Sistema Nervoso Central/patologia , Criança , Pré-Escolar , Estudos de Coortes , Meios de Contraste , Cistos , Feminino , Seguimentos , Humanos , Lactente , Recém-Nascido , Masculino , Neoplasias Hipofisárias/epidemiologia , Neoplasias Hipofisárias/patologia , Prevalência , Estudos Retrospectivos , Medição de Risco
13.
Nat Commun ; 10(1): 1583, 2019 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-30952855

RESUMO

Humans are often inconsistent (irrational) when choosing among simple bundles of goods, even without any particular changes to framing or context. However, the neural computations that give rise to such inconsistencies are still unknown. Similar to sensory perception and motor output, we propose that a substantial component of inconsistent behavior is due to variability in the neural computation of value. Here, we develop a novel index that measures the severity of inconsistency of each choice, enabling us to directly trace its neural correlates. We find that the BOLD signal in the vmPFC, ACC, and PCC is correlated with the severity of inconsistency on each trial and with the subjective value of the chosen alternative. This suggests that deviations from rational choice arise in the regions responsible for value computation. We offer a computational model of how variability in value computation is a source of inconsistent choices.


Assuntos
Comportamento de Escolha , Modelos Neurológicos , Adolescente , Adulto , Encéfalo/fisiologia , Mapeamento Encefálico , Tomada de Decisões , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino
15.
Clin Pract Cases Emerg Med ; 2(1): 97-98, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29849302
16.
Abdom Radiol (NY) ; 43(9): 2246-2254, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29500650

RESUMO

Intestinal malrotation is a continuum of congenital anomalies due to lack of rotation or incomplete rotation of the fetal intestine around the superior mesenteric artery axis. The abnormal bowel fixation (by mesenteric bands) or absence of fixation of portions of the bowel increases the risk of bowel obstruction, acute or chronic volvulus, and bowel necrosis. The clinical presentation of patients with malrotation without, with intermittent, or with chronic volvulus can be problematic, with an important minority presenting late or having atypical or chronic symptoms, such as intermittent vomiting, abdominal pain, duodenal obstruction, or failure to thrive. The diagnosis is heavily reliant on imaging. Upper GI series remain the gold standard with the normal position of the duodenojejunal junction lateral to the left-sided pedicles of the vertebral body, at the level of the duodenal bulb on frontal views and posterior (retroperitoneal) on lateral views. However, a variety of conditions might influence the position of the duodenojejunal junction, potentially leading to a misdiagnosis of malrotation. Such conditions include improper technique, gastric over distension, splenomegaly, renal or retroperitoneal tumors, liver transplant, small bowel obstruction, the presence of properly or malpositioned enteric tubes, and scoliosis. All of these may cause the duodenojejunal junction to be displaced. We present a series of cases highlighting conditions that mimic malrotation without volvulus to increase the practicing radiologist awareness and help minimize interpretation errors.


Assuntos
Obstrução Intestinal/diagnóstico por imagem , Volvo Intestinal/diagnóstico por imagem , Radiografia Abdominal/métodos , Diagnóstico Diferencial , Humanos , Lactente , Recém-Nascido , Obstrução Intestinal/congênito , Volvo Intestinal/congênito
18.
Nucl Med Commun ; 36(7): 717-21, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25888357

RESUMO

OBJECTIVE: Hyperglycemia has been shown to influence fluorine-18 fluorodeoxyglucose ((18)F-FDG) uptake in tumor cells. Therefore, patients are instructed to fast for 6 h, while maintaining serum glucose levels at an acceptable range. The study was performed to evaluate the effect of fasting blood glucose levels on the biodistribution of (18)F-FDG in various tissues including the liver, heart, bone marrow, skeletal muscle, and tumors. MATERIALS AND METHODS: Fingerstick fasting blood glucose is routinely measured on the morning of the procedure. The maximum standardized uptake value (SUV(max)) in the right and left hepatic lobes, left ventricle, sacrum, thigh, and tumor was measured in 229 consecutive patients undergoing (18)F-FDG PET/computed tomography for tumor. Patients were divided into three groups depending on their serum glucose levels: low (<100; n = 53), medium (100-160; n = 149), and high (160-201; n = 27). A retrospective analysis of the relationship between glucose levels and standardized uptake value was performed. RESULTS: There was a statistically significant increase in the average SUV(max) in the right and left hepatic lobes as glucose levels increased (right lobe P=0.00144; left lobe P = 0.03889). Subsequently, pairwise analysis was performed, revealing a statistically significant increase in SUV(max) in the right hepatic lobe between low-glucose and medium-glucose groups and in both hepatic lobes between low and high groups (P < 0.017). No significant difference was observed in any of the other measured tissues. CONCLUSION: This study shows a directly proportional relationship between blood glucose levels and nonpathologic (18)F-FDG biodistribution in the right and left hepatic lobes. The influence of blood glucose on expected biodistribution patterns, particularly in the liver, should be considered during interpretation.


Assuntos
Glicemia/metabolismo , Fluordesoxiglucose F18/farmacocinética , Tomografia por Emissão de Pósitrons/métodos , Compostos Radiofarmacêuticos/farmacocinética , Tomografia Computadorizada por Raios X/métodos , Idoso , Humanos , Pessoa de Meia-Idade , Imagem Multimodal/métodos , Estudos Retrospectivos , Distribuição Tecidual
19.
Curr Opin Behav Sci ; 5: 91-99, 2015 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-26722666

RESUMO

Empirical decision-making in diverse species deviates from the predictions of normative choice theory, but why such suboptimal behavior occurs is unknown. Here, we propose that deviations from optimality arise from biological decision mechanisms that have evolved to maximize choice performance within intrinsic biophysical constraints. Sensory processing utilizes specific computations such as divisive normalization to maximize information coding in constrained neural circuits, and recent evidence suggests that analogous computations operate in decision-related brain areas. These adaptive computations implement a relative value code that may explain the characteristic context-dependent nature of behavioral violations of classical normative theory. Examining decision-making at the computational level thus provides a crucial link between the architecture of biological decision circuits and the form of empirical choice behavior.

20.
J Neurosci ; 34(48): 16046-57, 2014 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-25429145

RESUMO

Normalization is a widespread neural computation, mediating divisive gain control in sensory processing and implementing a context-dependent value code in decision-related frontal and parietal cortices. Although decision-making is a dynamic process with complex temporal characteristics, most models of normalization are time-independent and little is known about the dynamic interaction of normalization and choice. Here, we show that a simple differential equation model of normalization explains the characteristic phasic-sustained pattern of cortical decision activity and predicts specific normalization dynamics: value coding during initial transients, time-varying value modulation, and delayed onset of contextual information. Empirically, we observe these predicted dynamics in saccade-related neurons in monkey lateral intraparietal cortex. Furthermore, such models naturally incorporate a time-weighted average of past activity, implementing an intrinsic reference-dependence in value coding. These results suggest that a single network mechanism can explain both transient and sustained decision activity, emphasizing the importance of a dynamic view of normalization in neural coding.


Assuntos
Córtex Cerebral/fisiologia , Tomada de Decisões/fisiologia , Rede Nervosa/fisiologia , Tempo de Reação/fisiologia , Animais , Previsões , Macaca mulatta , Estimulação Luminosa/métodos , Distribuição Aleatória
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...