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INTRODUCTION: Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder that affects 3% of children in the world. OBJECTIVE: In this work, we seek to compare the different brain activations of pediatric patients with and without ADHD. METHODS: A functional resonance examination with BOLD contrast was applied using the MOXO-CPT test (Continuous Performance test with single and double visual-auditory distractors). RESULTS: Differences in BOLD activation were observed indicating that control children regularly presented negative BOLD activations that were not found in children with ADHD. Inhibitory activity in audiovisual association zones in control patients was greater than in patients with ADHD. The inhibition in the frontal and motor regions in the controls contrasted with the overactivation of the motor areas in patients with ADHD, this, together with the detection of cerebellar activation which attempted to modulate the responses of the different areas that lead to executive failure in patients with ADHD. CONCLUSIONS: In view of these results, it can be argued that the lack of inhibition of ADHD patients in their executive functions led to a disorganization of the different brain systems.
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Transtorno do Deficit de Atenção com Hiperatividade , Córtex Motor , Humanos , Criança , Transtorno do Deficit de Atenção com Hiperatividade/diagnóstico , Encéfalo , Função Executiva , Cerebelo , Imageamento por Ressonância MagnéticaRESUMO
BACKGROUND: Evidence shows that greenspace exposure benefits children's health and cognitive development. However, evidence assessing this association in young children in low- and middle-income economies is scarce. OBJECTIVE: To assess the association between exposure to greenness and cognitive performance in pre-pubertal boys living in Mexico City. METHODS: Cross-sectional study using data from 144 boys aged 6-11 years living in Mexico City in 2017 and enrolled in the "MetCog" study. Cognitive performance was evaluated through selected Wechsler Scale for Intelligence in Children Fourth Edition (WISC-IV) and Neuropsychological Assessment of Children (Evaluación Neuropsicológica Infantil, ENI) tests. Exposure to greenness was assessed through Normalised Difference Vegetation Index (NDVI) at 300, 500, 1500, 2000, and 3000 m buffer zones from children's residences. Multiple linear regression analysis was undertaken to assess associations between cognitive performance and greenness (aß) with 95% confidence intervals (CI) and adjusted for potential confounding variables. Significance was set at q < 0.05 after False Discovery Rate (FDR) correction. RESULTS: A positive association was found between the NDVI Interquartile Range (IQR) at 2000 m and the WISC-IV block design test score (aß 2000 = 1.18, 95% CI = 0.31, 2.06; q < 0.05), which assesses perceptual reasoning. Positive associations were found with NDVI IQR at 1500 m and WISC-IV block design (aß1500 = 1.00, 95% CI = 0.14, 1.86) and matrix reasoning (aß1500 = 0.83, 95% CI = 0.06, 1.61) scores, but neither survived FDR correction. No significant associations were found between NDVI IQR at any buffer size with other WISC-IV and ENI task scores. CONCLUSIONS: Greater exposure to greenness was associated with higher perceptual reasoning skills in 144 pre-pubertal boys living in Mexico City. Thus, urban planning should consider increasing vegetation in megacities, especially in neighbourhoods with high percentages of young children.
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Nomogramas , Neoplasias da Bexiga Urinária , Humanos , Imageamento por Ressonância Magnética , Imagem de Difusão por Ressonância Magnética , Neoplasias da Bexiga Urinária/diagnóstico por imagem , Neoplasias da Bexiga Urinária/cirurgia , Músculos/diagnóstico por imagem , Estudos RetrospectivosRESUMO
The aim of this work was to use TOPAS Monte Carlo simulations to model the effect of magnetic fields on dose distributions in brachytherapy lung treatments, under ideal and clinical conditions. Idealistic studies were modeled consisting of either a monoenergetic electron source of 432 keV, or a polyenergetic electron source using the spectrum of secondary electrons produced by 192Ir gamma-ray irradiation. The electron source was positioned in the center of a homogeneous, lung tissue phantom (ρ = 0.26 g/cm3). Conversely, the clinical study was simulated using the VariSource VS2000 192Ir source in a patient with a lung tumor. Three contoured volumes were considered: the tumor, the planning tumor volume (PTV), and the lung. In all studies, dose distributions were calculated in the presence or absence of a constant magnetic field of 3T. Also, TG-43 parameters were calculated for the VariSource and compared with published data from EGS-brachy (EGSnrc) and PENELOPE. The magnetic field affected the dose distributions in the idealistic studies. For the monoenergetic and poly-energetic studies, the radial distance of the 10% iso-dose line was reduced in the presence of the magnetic field by 64.9% and 24.6%, respectively. For the clinical study, the magnetic field caused differences of 10% on average in the patient dose distributions. Nevertheless, differences in dose-volume histograms were below 2%. Finally, for TG-43 parameters, the dose-rate constant from TOPAS differed by 0.09% ± 0.33% and 0.18% ± 0.33% with respect to EGS-brachy and PENELOPE, respectively. The geometry and anisotropy functions differed within 1.2% ± 1.1%, and within 0.0% ± 0.3%, respectively. The Lorentz forces inside a 3T magnetic resonance machine during 192Ir brachytherapy treatment of the lung are not large enough to affect the tumor dose distributions significantly, as expected. Nevertheless, large local differences were found in the lung tissue. Applications of this effect are therefore limited by the fact that meaningful differences appeared only in regions containing air, which is not abundant inside the human.
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Braquiterapia/métodos , Neoplasias Pulmonares/radioterapia , Pulmão/efeitos da radiação , Campos Magnéticos , Braquiterapia/estatística & dados numéricos , Simulação por Computador , Relação Dose-Resposta à Radiação , Elétrons , Humanos , Radioisótopos de Irídio/administração & dosagem , Radioisótopos de Irídio/farmacocinética , Radioisótopos de Irídio/uso terapêutico , Imageamento por Ressonância Magnética , Método de Monte Carlo , Imagens de Fantasmas , Compostos Radiofarmacêuticos/administração & dosagem , Compostos Radiofarmacêuticos/farmacocinética , Compostos Radiofarmacêuticos/uso terapêutico , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Distribuição TecidualRESUMO
INTRODUCTION: Lisdexamfetamine (LDX) is a drug used to treat ADHD/impulsive patients. Impulsivity is known to affect inhibitory, emotional and cognitive function. On the other hand, smell and odor processing are known to be affected by neurological disorders, as they are modulators of addictive and impulsive behaviors specifically. We hypothesize that, after LDX ingestion, inhibitory pathways of the brain would change, and complementary behavioral regulation mechanisms would appear to regulate decision-making and impulsivity. METHODS: 20 children were studied in an aleatory crossover study. Imaging of BOLD-fMRI activity, elicited by olfactory stimulation in impulsive children, was performed after either LDX or placebo ingestion. RESULTS: Findings showed that all subjects who underwent odor stimulation presented activations of similar intensities in the olfactory centers of the brain. This contrasted with inhibitory regions of the brain such as the cingulate cortex and frontal lobe regions, which demonstrated changed activity patterns and intensities. While some differences between the placebo and medicated states were found in motor areas, precuneus, cuneus, calcarine, supramarginal, cerebellum and posterior cingulate cortex, the main changes were found in frontal, temporal and parietal cortices. When comparing olfactory cues separately, pleasant food smells like chocolate seemed not to present large differences between the medicated and placebo scenarios, when compared to non-food-related smells. CONCLUSION: It was demonstrated that LDX, first, altered the inhibitory pathways of the brain, secondly it increased activity in several brain regions which were not activated by smell in drug-naïve patients, and thirdly, it facilitated a complementary behavioral regulation mechanism, run by the cerebellum, which regulated decision-making and impulsivity in motor and frontal structures.
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Encéfalo/efeitos dos fármacos , Estimulantes do Sistema Nervoso Central/farmacologia , Comportamento Impulsivo/efeitos dos fármacos , Dimesilato de Lisdexanfetamina/farmacologia , Encéfalo/diagnóstico por imagem , Encéfalo/fisiopatologia , Criança , Estudos Cross-Over , Sinais (Psicologia) , Lobo Frontal/diagnóstico por imagem , Lobo Frontal/efeitos dos fármacos , Neuroimagem Funcional , Giro do Cíngulo/diagnóstico por imagem , Giro do Cíngulo/efeitos dos fármacos , Humanos , Imageamento por Ressonância Magnética , Masculino , Inibição Neural/efeitos dos fármacos , Odorantes , Córtex Olfatório/diagnóstico por imagem , Córtex Olfatório/efeitos dos fármacos , Lobo Parietal/diagnóstico por imagem , Lobo Parietal/efeitos dos fármacos , Lobo Temporal/diagnóstico por imagem , Lobo Temporal/efeitos dos fármacosRESUMO
BACKGROUND: Impulsivity is a complex multi-dimensional combination of behaviors which include: ineffective impulse control, premature decision-making and inability to delay gratification. OBJECTIVE: The aim of this work was to explore how food odor perception and its emotional value is affected in impulsive children. METHODS: Here we compared two cohorts of impulsive and control children with ages between 10 and 16 years. Both groups underwent a functional magnetic resonance imaging experiment, in which foodrelated odor-cues were presented to all of them. RESULTS: Differences in regions of blood oxygen level dependent activation, as well as connectivity, were calculated. Activations were significant for all odors in the impulsive group in the temporal lobe, cerebellum, supplementary motor area, frontal cortex, medial cingulate cortex, insula, precuneus, precentral, para-hippocampal and calcarine cortices. CONCLUSION: Connectivity results showed that the expected emotional reward, based on odor perceived and processed in temporal lobes, was the main cue driving responses of impulsive children. This was followed by self-consciousness, the sensation of interaction with the surroundings and feelings of comfort and happiness, modulated by the precuneus together with somatosensory cortex and cingulum. Furthermore, reduced connectivity to frontal areas as well as to other sensory integration areas (piriform cortex), combined to show different sensory processing strategies for olfactory emotional cues in impulsive children. Finally, we hypothesize that the cerebellum plays a pivotal role in modulating decision-making for impulsive children.
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Encéfalo/fisiopatologia , Comportamento Impulsivo/fisiologia , Vias Neurais/fisiologia , Percepção Olfatória/fisiologia , Adolescente , Estudos de Casos e Controles , Criança , Sinais (Psicologia) , Emoções , Feminino , Alimentos , Neuroimagem Funcional , Humanos , Imageamento por Ressonância Magnética , Masculino , OdorantesRESUMO
BACKGROUND & OBJECTIVE: Adult neurogenesis, a specific form of brain plasticity in mammals that occurs in the subventricular zone, is subject to complex regulation. Hypocretin/orexin neurons are implicated in the regulation of sleep and arousal states, among other functions. Here we report for the first time the presence of orexinergic projections within the adult rat subventricular zone. Post-mortem retrograde tracing combined with immunofluorescence indicated orexinergic projections toward the subventricular zone. To establish the relationship between the depletion of orexin neurons and the number of proliferating cells in the subventricular zone, we labeled mitotic cells. Histological analysis revealed proliferating cells to be in close contact with orexinergic fibers. Neurotoxinlesioning of orexin neurons in the lateral hypothalamus significantly activated precursor cell proliferation in the subventricular zone. Furthermore, cell proliferation in both normal and lesioned animals failed to reveal newly born orexin neurons in the lateral hypothalamus. CONCLUSION: Based on these findings, we suggest that the adult subventricular zone is affected by orexinergic signaling, the functional implication of which must be further elucidated.
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Proliferação de Células , Ventrículos Laterais/citologia , Neurogênese/fisiologia , Neurônios/metabolismo , Orexinas/deficiência , Saporinas/deficiência , Animais , Região Hipotalâmica Lateral/efeitos dos fármacos , Região Hipotalâmica Lateral/fisiologia , Masculino , Vias Neurais/fisiologia , Técnicas de Rastreamento Neuroanatômico , Neurogênese/efeitos dos fármacos , RatosRESUMO
Parkinson's disease (PD) affects at least 10 million people worldwide. It is a neurodegenerative disease, which is currently diagnosed by neurological examination. No neuroimaging investigation or blood biomarker is available to aid diagnosis and prognosis. Most effort toward diagnosis using magnetic resonance (MR) has been focused on the use of structural/anatomical neuroimaging and diffusion tensor imaging (DTI). However, deep brain stimulation, a current strategy for treating PD, is guided by MR imaging (MRI). For clinical prognosis, diagnosis, and follow-up investigations, blood oxygen level-dependent MRI, DTI, spectroscopy, and transcranial magnetic stimulation have been used. These techniques represent the state of the art in the last 5 years. Here, we focus on MR techniques for the diagnosis and treatment of Parkinson's disease.
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The objective of this research was to describe the organization, connectivity and microstructure of the corpus callosum of the spider monkey (Ateles geoffroyi). Non-invasive magnetic resonance imaging and diffusion-tensor imaging were obtained from three subjects using a 3T Philips scanner. We hypothesized that the arrangement of fibers in spider monkeys would be similar to that observed in other non-human primates. A repeated measure (n = 3) of fractional anisotropy values was obtained of each subject and for each callosal subdivision. Measurements of the diffusion properties of corpus callosum fibers exhibited a similar pattern to those reported in the literature for humans and chimpanzees. No statistical difference was reached when comparing this parameter between the different CC regions (p = 0.066). The highest fractional anisotropy values corresponded to regions projecting from the corpus callosum to the posterior cortical association areas, premotor and supplementary motor cortices. The lowest fractional anisotropy corresponded to projections to motor and sensory cortical areas. Analyses indicated that approximately 57% of the fibers projects to the frontal cortex and 43% to the post-central cortex. While this study had a small sample size, the results provided important information concerning the organization of the corpus callosum in spider monkeys.