View clinical trials related to fMRI.
Filter by:The goal of this observational study is to identify the characteristics of brain functional connectivity in refractory constipation and fluoxetine-sensitive patients. The main questions it aims to answer are: - Investigating the alterations in brain functional connectivity in patients with refractory constipation and fluoxetine-sensitive patients - Assessing the predictive value of brain functional connectivity regarding the efficacy of fluoxetine and standard protocol treatments for constipation. Participants will receive: - Standard physiological and psychological assessments of constipation - BOLD-fMRI tests - Standard protocol and fluoxetine treatment If there is a comparison group: Researchers will compare: Refractory group/Fluoxetine sensitive group to see the specific brain alterations.
Assess the impact of a remote, app-delivered digital meditation intervention on emotional well-being of lonely older adults. Neuroimaging and autonomic physiology will be used to assess the neural correlates of the intervention.
The cognitive trajectory varies among non-demented older adults. In a 12-year follow-up study, we found approximately 5% participants presented rapid cognitive decline. Cardiovascular diseases increased the risk of cognitive decline. However, the influence of cardiovascular risk factors on cognitive decline remained inconsistent. Besides, the potential mechanism of the cardiovascular risk factors and cognitive function has not been fully investigated. Therefore, the proposed program will include two sub-studies. The first sub-study will use the longitudinal data from the Chinese Longitudinal Healthy Longevity Survey to evaluate the influence of cardiovascular risk factors on the trajectories of cognitive function. The second sub-study will recruit cognitive intact older adults with different levels of cardiovascular risk factors. The association among cardiovascular risk factors, cerebral blood flow, brain functional connectivity and cognitive function will be investigated with structural equation modeling. The findings of the proposed program will provide novel insight on preventing cognitive decline from the angle of maintaining healthy vascular function, and will provide evidence in elucidating the potential neurovascular mechanism between cardiovascular risk factors and cognitive function.
Transcutaneous vagal nerve stimulation (tVNS) has been applied to a number of disease areas including visceral pain, depression, cluster headache and Alzheimer's disease. However, there is marked heterogeneity in these studies pertaining to i) the anatomical site of stimulation (neck, inner concha or tragus of ear), and ii) the waveform parameters of the stimulating impulse. This exploratory cross-sectional study will address these knowledge gaps by comparative functional neuroimaging of the neural correlates of tVNS with disparate anatomical sites and electrical waveform characteristics during rest in healthy participants.
People utilize two behavioral strategies, goal-directed and habitual, when engaging in value-based decision-making that involves rewarding or punishing outcomes. Accumulating evidence suggests an imbalance between habitual and goal-directed behavior in favor of habitual control in parallel with exaggerated tendency toward compulsive/harm avoidance behavior in OCD. In healthy subjects, an arbitration mechanism has been proposed recently that controls the balance between those two strategies of action selection. Arbitration regions regulate the goal-directed/habitual decision-making balance by selectively downregulating the activity of the habitual regions. This project aims to explore the neurobehavioral characteristics of arbitration mechanism and its relationship with behaviors and clinical phenotypes in OCD by applying computational cognitive neuroscience, clinical task-based functional magnetic resonance imaging (fMRI) and transcranial direct current stimulation (tDCS) method.
Background: -The brain has two systems for recognizing objects. One system recognizes what an object is, and the other system recognizes where the object is located. However, there is much about how the brain handles and interprets the information from these two systems that is still unclear. Researchers want to study the parts of the brain that are involved in how vision is processed. They will use magnetic resonance imaging (MRI) and transcranial magnetic stimulation (TMS) or transcranial electrical stimulation (tES) on the brain. MRI measures what parts of the brain become more active when tasks are performed. TMS uses magnetic pulses to temporarily change the activity in parts of the brain. tES uses electrical current to temporarily change brain function. Objectives: -To better understand how people visually recognize different types of objects. Eligibility: -Healthy volunteers between 18 and 50 years of age, who only speak English. Design: - This study includes many different experiments on vision. Each experiment may combine visual tasks, MRI scans, and TMS or tES. Participants may be asked to have several different tests. Each test will require a separate visit to the National Institutes of Health. - Participants will be screened with a physical exam and medical history. They will have a baseline brain scan at the first visit. - Participants may do visual tasks alone, with MRI only, with TMS or tES only, or with MRI and TMS or tES combined. For the visual tasks, they will look at pictures of objects on a computer screen. Sometimes the images will appear very briefly (less than one-tenth of a second). Sometimes they will appear for up to 5 seconds. These images will be of things like faces, bodies, tools, and scenes. Participants will be asked to respond in different ways to the pictures. They may respond by typing on a computer keyboard or by pressing a button. Participants will have time to practice the tasks before the experiment. - Participants will remain on the study for up to 3 years.
Despite the clear importance of adolescence in the emergence of a number of disease states and processes, there is surprisingly little known about how the endocrine and metabolic events accompanying puberty in humans impact normal developmental neurobiology. Epidemiologic studies have identified sexual dimorphisms in the prevalence of several neuropsychiatric disorders, including depression, schizophrenia, and substance abuse. Many of these sex differences emerge during or shortly after puberty and are maintained until the 5th-6th decade of life. For example, the two-fold greater risk of unipolar depression in women compared with men does not appear until adolescence, and prior to puberty girls are not at increased risk relative to boys. Puberty is a structured, transitional process that can be influenced by both nutritional factors and environmental stressors; nonetheless, the variability in the timing and duration of puberty is largely determined by oligogenic inheritance. Basic neuroscience research has demonstrated that hormonal events accompanying puberty impact on many of the physiologic systems involved in the regulation of brain function (e.g., the appearance of new neurons in a brain-region specific pattern, neuronal remodeling, and the pruning of cortical connectivity). Additionally, not only does stress during puberty increase the risk of disturbances in affective adaptation during adulthood, but the events accompanying puberty modify stress responsivity (e.g., alterations in the duration and peak response of hypothalamic-pituitary-adrenal [HPA] axis hormones to stressors). Moreover, animal work has demonstrated that neural connectivity differs in a brain regional specific manner according to the stage of puberty (i.e., early versus late). In humans, puberty also occurs in stages, and although the endocrinology of puberty, surprisingly, has not been fully characterized with longitudinal data, studies have documented that the physical changes measured by Tanner stages I to V are accompanied by progressive increases in the secretions of both gonadal and adrenal steroids. Nonetheless, there remains considerable variability in the timing and duration of this otherwise highly structured reproductive transition. We propose to perform a longitudinal, naturalistic study examining changes in brain structure and function, behavior, and stress responsivity in boys and girls across the pubertal transition. Because the pubertal transition is defined by a complex series of physiologic events that emerge sequentially over several years and involve changes in multiple endocrine and growth systems, and because there is also considerable variability in the timing of these events reflecting the influence of both genetic and environmental factors, puberty cannot by delineated by age of the participants as has been done in most imaging and other neurobiological studies of adolescence. The present study will formally bridge this gap by defining pubertal events per se in participants. Participants will include healthy boys and girls whose pubertal status will be assessed, and in whom endocrine, metabolic, and brain imaging measures will be evaluated at eight - ten month intervals from age eight years (pre-puberty) until age 17 years (post-puberty). Reproductive endocrine, metabolic, and physical measures will be employed to characterize the stage and duration of pubertal development. Outcome measures will be derived via multimodal neuroimaging techniques, cognitive/behavioral assessments, metabolic measurements, and evaluations of HPA axis function. Additionally, the impact of genetic variation on the developmental trajectory of these parameters (both reproductive and CNS) will be determined. This cross-institute proposal will employ a multidisciplinary approach to evaluating the effects on CNS function of the process of puberty in both boys and girls. This work will not only serve to inform research on the mechanisms by which sexual dimorphisms in neuropsychiatric disorders develop, it will also have important implications for the prevention and treatment of these disorders. ...
Background: - Previous studies have shown that people with certain types of brain damage may have particular problems paying attention and processing things that they see. Researchers are interested in comparing how people with brain damage and without brain damage process visual images. Objectives: - To better understand the areas of the brain involved in paying attention to things that are seen. Eligibility: - Individuals at least 18 years of age who either have had damage to one or both sides of specific parts of the brain (e.g., stroke, injury, certain neurosurgery procedures) or are healthy volunteers. Design: - The study involves 4 to 10 visits to the NIH Clinical Center over 1 to 2 years. Each visit will last approximately 2 hours. - Participants will be screened with a medical history and physical examination, and may have the cognitive testing described below during the same visit. - On the first visit and for at least one visit thereafter, participants will have cognitive testing to evaluate thinking and memory. These tests will be either written tests or computer-based tests. - Some participants will qualify for functional magnetic resonance imaging (fMRI) as part of the study. This part will involve a decision-making task that will be performed on a computer during the fMRI scan. Additional scans may be required as directed by the study doctors. - Some randomly selected participants will be asked to have magnetoencephalography (MEG), a procedure to record very small magnetic field changes produced by brain activity. - During the behavioral training, or fMRI or MEG scanning, participants may be monitored with equipment to track eye movements.
The purpose of this investigation is to develop improved magnetic resonance imaging (MRI) techniques and hardware for studying brain function. MRI is a diagnostic tool that provides information about brain chemistry and physiology. This study will evaluate new MRI methods for monitoring blood flow to regions of the brain in response to simple tasks. The MRI machine used in this study is more powerful than those in most hospitals, permitting a higher visual resolution. Normal healthy volunteers over 18 years old may be eligible for this study. Candidates will be screened with a medical history and questionnaire, and a neurological examination. Study participants will have a yearly MRI scan. For this procedure, the subject lies on a stretcher that is moved into a donut-shaped machine with a strong magnetic field. A lightweight circular or rectangular coil a device that improves the quality of the images may be placed on the head. The scan time varies from 20 minutes to 3 hours; most scans last between 45 and 90 minutes. During the scan, the subject may perform simple tasks, such as listening to tapes, tapping a finger, moving a hand, watching a screen, or smelling a fragrance. More complex tasks may require thinking about tones or pictures and responding to them by pressing buttons. Information from this study will be used to develop better imaging methods that will, in turn, permit a greater understanding of normal and abnormal brain behaviors.