Clinical Research Directory

Perception, Sensation, Cognition and Action in Humans

Background: When people see and hear, the brain changes signals from the eyes and ears into perceptions and thoughts. No one fully understands how this happens. Researchers want to explore how healthy brains process sights and sounds. Objectives: To explore how people understand what they see and hear when the brain processes sights and sounds. Eligibility: Participants aged 13-65 who have at least 20/40 vision in at least one eye and do not use a hearing aid. Design: Some participants will take tests online anonymously. They will do computer tasks related to colors and behavior. In-person participants will be screened with medical history and physical exam. They will complete questionnaires and vision and hearing tests. Participants will plan how many testing sessions they will have and when. Sessions last 2-5 hours. They may include: * Magnetic Resonance Imaging: Magnets and radio waves to take pictures of the brain. Participants will lie on a table that slides in and out of a tube. They will do a task during the scan. * Magnetoencephalography: Records magnetic field changes from brain activity. Participants will sit or lie down. A cone will be lowered onto their head. They may do a task during the test. * Electromyography: Electrodes attached to the skin will measure the electrical activity of muscles. * Electroencephalogram: Electrodes on the scalp will record brain waves. * Electrocardiography: Electrodes on the chest will record heart electrical activity. * Tests of memory, attention, thinking, vision, and hearing. * Eye Tracking: Cameras will follow participants eye movements. They may wear a cap with infrared cameras in front of their eyes. During the sessions, participants vital signs may be monitored.

Development and Validation of Learning and Decision-Making Tasks

Background: Substance use disorders (SUD) can be considered disorders in the way people process incentives, learn, and make decisions. To understand why some people develop SUD, researchers need to develop reliable tests that show how people think and learn. This natural history study seeks to develop a set of tasks that could then be used to test how people learn and make decisions. Objective: To develop and validate behavioral tasks that could be used in future studies. Eligibility: Healthy people aged 18-45 years from the Baltimore area. They must also be enrolled in the NIDA screening protocol. Design: Participants will perform different tasks. Most tasks require 1-4 study visits; some may require up to 12. Visits are 1-14 days apart. All visits will last about 1-7 hours. Participants will perform tasks on a computer. As they work they may be given different stimuli: Smells. Participants will sniff odors through a plastic tube or mask on their nose. Flavors. Participants will wear a mouthpiece and small amounts of different flavored liquids will be placed in their mouth. Pictures. Participants will look at different images. Sounds. Participants will wear headphones and various sounds will be played for them. Food. Participants may be asked to eat a meal before, during, or after a task. The researchers will provide the meal. During each task, participants will wear sensors to monitor their heart rate, blood pressure, breathing, and other physical changes in their bodies. Some participants will have a functional magnetic resonance imaging (fMRI) scan. They will lie on a table that slides into a cylinder. They will perform tasks on a computer screen during the fMRI.

Causal Mechanisms of Odor-Guided Behavior in Humans

Background: Little is known about how different regions of the brain responsible for the human sense of smell guide behaviors. In this study, researchers use a technique called transcranial ultrasound stimulation (TUS) to learn how odors affect the brain and behavior. Objective: To learn more about how the human sense of smell works. Eligibility: Healthy people aged 18 to 45 years who are right-handed. Design: Participants can volunteer for up to 2 different experiments. Each experiment requires 5 visits, each about 1 week apart. Food, alcohol, and caffeine may be limited before visits. At the start of each visit, participants will answer questions about their health and how well they slept. Their sense of smell will be assessed. Some visits may include tasks on a computer: While doing these tasks, participants may be asked to smell different odors, look at pictures, and listen to sounds. They will wear devices to track breathing, blood pressure, pulse, and other body responses to the tasks. Some visits may include TUS: TUS uses ultrasound waves to briefly change brain activity. A gel will be applied to the scalp and hair, and a device will be placed against the participant s head. Participants may feel a tapping, pulling, and/or warm sensation on the skin underneath the device. They may also feel a twitch in their face, neck, arm, or leg muscles. Participants will do tasks before and after TUS. Some visits will include functional magnetic resonance imaging (fMRI) scans. fMRI uses magnet and radio waves to capture images of the activity inside the brain. Participants will lie on a table that slides into a tube. They will perform tasks inside the scanner.

Sociocultural & Biobehavioral Influences on Pain Expression and Assessment

Objective The current proposal investigates behavioral, psychophysiological, and social processes that may help explain biases and disparate outcomes in pain. Health disparities, or health outcomes that adversely affect disadvantaged populations, are pervasive and apparent in many diseases and symptoms, including pain. Pain is the number one reason individuals seek medical treatment. Health disparities in pain encompass both differences in pain experience and treatment for pain. For instance, research indicates that Black individuals report increased pain and have reduced pain tolerance relative to White individuals, yet doctors are less likely to treat minority patients pain and underestimate their pain experience. This project aims to address this systemic discrepancy by focusing on interpersonal processes that may contribute to these disparities, including socially-relevant responses to pain (i.e. pain expression) and pain assessment (e.g. visual attention). The proposed research aims to determine whether the study of pain expressions and their assessment can yield insights on how social factors shape pain and its treatment. Further, we test the efficacy of potential interventions designed to improve accuracy and reduce biases in pain assessment. If successful, this work will form the foundation of a new research program that will link the field of pain research with the field of social neuroscience, and forge new insights on the critical problem of health disparities in pain. Study population We will accrue up to 700 total healthy volunteers to target 240 completers Design Our overall aim is to understand how social factors influence the assessment and management of pain, and to gain insight into psychosocial processes that may underlie health disparities in pain. We propose a series of studies designed to test these links. First, we will measure pain perception and physiological responses to painful stimuli in a diverse group of individuals to test for sociocultural and biological influences on pain and pain-related responses. In subsequent studies, new participants ("perceivers") will view images of these initial participants ("targets") and will provide estimates of 'targets' pain experience. We will measure a) whether perceivers can accurately estimate 'targets' pain experience; b) whether accuracy differs as a function of similarity between target and perceiver (ingroup vs outgroup); and c) whether individuals can improve accuracy through feedback. Outcome measures Primary outcome measures for all experiments will be decisions about pain (experienced by self or other) measured with visual analogue scales, reaction time, and/or categorical judgments (pain/no pain). We will also measure physiological responses (e.g., facial muscle response, skin conductance, pupil dilation) and brain responses using functional magnetic resonance imaging (fMRI) as secondary outcome measures. We will test whether pain and pain-related responses varies as a function of sociocultural/demographic factors (e.g. race, ethnicity, sex) and whether accuracy in assessing others' pain is influenced by group similarity (i.e. ingroup vs. outgroup) and training (e.g. performance-related feedback)....

Developing Transcranial Neuromodulation Protocols for Learning and Decision-Making

Background: People with substance use disorder (SUD) often have changes in brain function that can make it difficult to control drug-seeking behavior. These changes may heighten the urge to use drugs or lessen the desire to seek nondrug-related rewards. Researchers want to know how a technique called transcranial magnetic stimulation (TMS) may cause changes in brain activity that may help people with SUD. Objective: To test TMS in healthy volunteers. Eligibility: Healthy people aged 18 to 45 years who are right-handed. Design: Participants can volunteer for up to 5 different experiments. Each experiment requires 2 to 8 clinic visits. Each visit will last 3 to 7 hours. Some visits will include TMS. A coil will be placed on the participant s head. A brief electrical current will pass through the coil to create a magnetic field. Participants may feel a tapping or pulling sensation on the skin under the coil. They may feel a twitch in their face, neck, arm, or leg muscles. Participants may be asked to tense certain muscles during TMS. Some visits will include functional magnetic resonance imaging (fMRI) scans. Participants will lie on a bed that slides into a large tube. They will perform tasks on a computer inside the tube. The fMRI will show which parts of the brain are used during each task. Participants will perform tasks on a computer. Some tasks may be done at a desk as well as during TMS and fMRI. Participants may look at images, listen to sounds, smell odors, or taste flavored liquids. Their vital signs may be monitored and their eye movements may be tracked during tasks.

Development Of Neuroimaging Methods To Assess The Neurobiology Of Addiction

Background: Abusing alcohol, drugs, and other substances can cause serious health problems. These substances also can affect brain function. Researchers want to learn more about brain function by using magnetic resonance imaging (MRI). This uses a magnetic field and radio waves to take pictures of the brain. Objective: To develop new ways to use MRI to study the brain. Eligibility: Healthy people 18 years of age or older. Design: Participants will be screened with a medical history, physical exam, and blood and urine tests. They will answer questions about their drug use and psychiatric history. They will be asked about family history of alcoholism or drug abuse. Participants will answer questions to see if they can participate in MRI. Participants will have MRI scans. The scanner is a metal cylinder in a strong magnetic field. Participants will lie on a table that slides in and out of the cylinder. A device called a coil may be placed over the head. Each sub-study will include up to 3 different MRI visits. Participants can be in multiple sub-studies. But they can have only 1 MRI per week and 20 per year. During MRI visits, participants may have urine collected. They may get another MRI questionnaire. Participants may have a clinical MRI brain scan. This may show physical problems in the brain. During some scans, participants may perform simple movement, memory, and thinking tasks. Participants may be connected to a machine to monitor brain activity during the scan. Small metal electrodes will be placed on the scalp. A gel will be placed in the space between the electrodes and the scalp.

Reliability of the Human Brain Connectome

Background: \- Magnetic resonance imaging (MRI) is used to investigate brain function. Researchers want to use MRI to better understand the function patterns and connections between brain regions in healthy people. This might help people with brain diseases in the future. Objectives: * To evaluate MRI methods performed twice on the same day. * To evaluate brain function using positron emission tomography (PET). Eligibility: \- Healthy volunteers at least 18 years old. Design: * Visit 1: * Participants will be screened with medical history, physical exam, and interview about drug and alcohol use and psychiatric history. * They will give blood and urine samples. Their breath will be tested for alcohol and smoking. * Visit 2: * Participants will have urine collected. They will have MRI scans, some while resting, some while doing tasks on a computer. * The MRI scanner is a metal cylinder in a strong magnetic field. Participants will lie on a table that slides in and out of the cylinder, with a coil over their head. Participants will get earplugs for loud noises. * Visit 3: * Participants will have urine collected. * A needle will guide a thin plastic tube (catheter) into each arm. The needle will be removed, leaving the catheter in the vein. * Participants will then have a PET scan. They will get the chemical 18FDG in the catheter. They will lie on a bed that slides in and out of the PET scanner, with a cap on their head. * Participants may have tests of memory, attention, concentration, and thinking. They may complete interviews, questionnaires, tests on paper or computer, and simple actions. * Participants will wear a device for 1 week between visits to measure activity and sleep.

Investigating the Impact of Obesity on Pubertal Development in Girls

Background: Studies suggest that overweight girls may be developing breast tissue, and therefore starting puberty, earlier than normal weight girls. However, it is hard to distinguish breast tissue from fatty tissue. Researchers think that by using breast ultrasound, among other tests, they can do a better job of telling whether an overweight girl has breast tissue. This will help them understand if overweight girls are truly entering puberty before normal weight girls. Objective: To find out if overweight girls go through puberty earlier than normal weight girls. Eligibility: Healthy girls 8-14 years old who: * Are normal weight or overweight * Have some breast development * Have not started their first period Design: Parents of participants will be screened over the phone. Most participants will have 1 visit. However, they can choose to have multiple visits within 4 weeks. The visit will include: * Physical exam that includes examination of the breasts and genital area * Breast ultrasound: A small hand-held device will be passed back and forth over the chest. It uses sound waves to create a picture of the breast tissue. * Pelvic ultrasound: A small, handheld device will be passed back and forth over the lower belly. It uses sound waves to create a picture of the ovaries. * Urine and blood test * A special x-ray called a DXA to measure the amount of fat in the body: The participant will lie still on a table while the x-ray takes pictures of the body. X-ray of the hand: The picture will tell researchers how mature the participant s bones are. Participants may be asked to come back 6 months later to repeat these tests.

Addictions Neuroclinical Assessment (ANA)

Background: Alcohol use disorder (AUD) is a major public health problem. In the U.S., 16 to 18 million adults have an AUD. Researchers want to test an assessment tool called the ANA. It uses self-report and behavioral measures to assess 3 neuroscience domains of addiction. They hope to better understand, manage, prevent, and treat AUD. Objective: To learn how people s brains function related to their drinking. Eligibility: People ages 18 years and older who have enrolled in NIAAA natural history study 14-AA-0181. Design: Participants will complete surveys and tasks on a computer. The surveys and tasks assess a range of aspects of thinking and making decisions. The surveys and tasks also assess behaviors and feelings about alcohol and other rewards, and negative emotions. Participants will spend 90 minutes on the computer. Then they will take a break. In total, they will spend 4 blocks of time on the computer. Each block will last 90 minutes. They will take a break in between each block of time. They can take more breaks if needed. Outpatient participants and healthy volunteers will complete this study in 1 visit. It will last about 6 hours. A second visit may be scheduled if needed. Outpatient participants will take a breath alcohol test. If their test is positive, their visit may be rescheduled or they may be withdrawn from the study. Inpatient participants will complete this study over several days. Data collected from participants in this study may be combined and analyzed with their data from NIAAA study 14-AA-0181 and/or NIAAA imaging study 14-AA-0080.

MRS Measurement of Glutamate and GABA Metabolism in Brain

This study will use magnetic resonance spectroscopy (MRS) to measure in the brain the transfer of \[13\]C as it is naturally metabolized from glucose to specific chemical transmitters. From this method, we can measure the rate of production of an important excitatory neurotransmitter (glutamate) as well as an inhibitory neurotransmitter (GABA).

Development of 3T Magnetic Resonance Research Methods for NIA Studies

Background: \- Magnetic resonance imaging (MRI) studies provide important information on the structure and function of various body systems, including the brain, muscles, joints, heart, and blood vessels. Scientific applications of MRI scans often use techniques that need to be modified or refined before they are used in clinical studies. To develop and modify these techniques for the new Philips 3T Achieva whole-body MRI scanner, researchers are interested in conducting trial MRI scans on healthy individuals and individuals with conditions that require imaging studies. Objectives: \- To conduct preliminary trials of the 3T MRI facility to develop and refine MRI scanning procedures. Eligibility: \- Individuals at least 18 years of age who are able to have magnetic resonance imaging. Design: * Participants will be screened with a full medical history and physical examination, as well as blood and urine tests. * Participants will have an MRI scan using the 3T scanner. Some scans may require the use of a contrast agent or radiotracer, which is a small amount of radioactive substance that will be injected before the start of the scan. Some participants may be asked to perform tasks of thinking and movement while in the scanner, in order to test the procedures required for a functional MRI scan. * No treatment will be provided as part of this protocol.

Microbial, Immune, and Metabolic Perturbations by Antibiotics (MIME Study)

More than 250 million courses of antibiotics are prescribed annually in the ambulatory care setting in the United States alone, including more than 40 million in children under 18 years of age. The perception that antibiotic use has minimal attendant adverse side effects contributes to the over-utilization of antibiotics in clinical circumstances when they are not strictly indicated. We have learned much about the human microbiome. The emerging view is of profound life-long bi-directional interactions between our microbiota and our cells. Perturbations in the microbiota affect metabolic, immune, and cognitive physiology in experimental animal models. When a person takes an antibiotic, the antibiotic diffuses via the blood into all body compartments, selecting for resistance. We propose to examine the effects of two commonly used antibiotics (the beta-lactam, amoxicillin and the macrolide azithromycin) on human microbial populations and on metabolic and immune physiology, studying healthy human volunteers in a randomized controlled clinical trial at the NIH Clinical Center. Our hypothesis is that in addition to acutely perturbing the human microbiome, these agents will have measurable metabolic and immunologic effects, with residual effects in the weeks that follow. To test this hypothesis, we will assess the effects of a brief therapeutic course of antibiotics on microbiome and metagenome composition. After an initial evaluation period, antibiotics will be given for 7 days or 5 days (depending on the antibiotic), and there will be a post-treatment evaluation. A control group will receive no drug intervention. Specimens will be obtained from multiple sites at each of 10 time points occurring before, during, and after antibiotic administration, and used for estimating bacterial and fungal composition and gene content. We will also assess the effects of the antibiotic course on markers of innate and adaptive immunity as well as markers of metabolic and hormonal physiology. A subgroup of subjects will be studied in the clinical center metabolic chamber to assess 24-hour energy expenditure and its components (sleeping, diet-induced, and activity energy expenditure), as well as macronutrient oxidation rates (carbohydrate, fat, and protein), during 3 of the 10 study visits. In addition to the primary data analyses, we will build a model that integrates the temporal data to begin to understand the complex intertwined physiology between microbiome and host.

Brain Amyloid- Retention During Wakefulness and Following Emergence From Sleep in Healthy People

Background: Brain activity creates waste products. The body s glymphatic system removes this waste, especially during sleep. One brain waste product is amyloid-beta (Ab). It plays a role in Alzheimer s disease. Researchers want to study the effect of sleep on Ab in the brain. Objective: To see if sleep affects the amount of waste product removed from the brain. Eligibility: Healthy people at least 18 years of age. Design: Participants will be screened with a medical history, physical exam, and blood and urine tests. They will answer questions about drug use, psychiatric history, and family history of alcoholism or drug use. Participants will complete an MRI screening questionnaire. Participants will stay in the clinic overnight two times. On one night they will sleep through the night. On the other night they will be kept awake all night. These overnight visits can happen in any order. Participants will wear 2 activity monitors, on the wrist and the ankle. Participants will have positron emission tomography (PET) scans. A small amount of a radioactive chemical will be injected through an intravenous (IV) catheter. Participants will lie on a bed that slides into the scanner. A cap or a special mask may be placed on the participant s head. Participants will have magnetic resonance imaging (MRI) scans. The MRI scanner is a metal cylinder in a strong magnetic field. Participants will lie on a table that slides into the cylinder. A device called a coil will be placed over the head. Participants will do a task on a computer screen in the scanner. Participants will have tests of thinking, memory, and attention. They may be interviewed, complete questionnaires, take pen-and-paper or computer tests, and perform simple actions.

Magnetic Resonance Imaging (MRI) of Neuropsychiatric Patients and Healthy Volunteers

The purpose of this study is to use brain imaging technology to compare differences in brain structure, chemistry, and functioning in individuals with brain and mental disorders compared to healthy volunteers. Schizophrenia is a brain disorder that results from subtle changes and abnormalities in neurons. These deficits likely occur in localized regions of the brain and may result in widespread, devastating consequences. The neuronal abnormalities are inherited through a complex combination of genetic and environmental factors. Brain imaging technologies can be used to better characterize brain changes in individuals with schizophrenia. This study will use magnetic resonance imaging (MRI) scans to identify predictable, quantifiable abnormalities in neurophysiology, neurochemistry and neuroanatomy that characterize schizophrenia and other neurological and neuropsychiatric disorders.

A Natural History Study of Metabolic Sizing in Health and Disease

Background: Scientists have long used simple measures (such as height and weight) to estimate how much a person s body uses food (calories) as energy, as commonly called the metabolic rate. But metabolism varies among people with similar body sizes. Scientists now believe the old formulas for estimating metabolic rates may not work well for all people. Researchers want to find more accurate ways to measure a person s metabolism. Objective: This natural history study will examine the relationships between metabolism, body composition, and body surface area in a wide range of people. Eligibility: Healthy children and adults aged 2 years or older. Also, people aged 2 years or older with conditions that may alter metabolism. These may include diabetes, obesity, renal disease, or cancer. Design: Participants will spend 2 days and 1 night in the hospital. They will provide a medical history and answer questions about their activity levels, the foods they eat, and their lifestyle. They will also eat a special diet. Participants will undergo many tests: They will lie in a bed with a clear hood covering their head for 30 to 45 minutes to measure the gases in their breath. They will lie on a padded table for about 15 minutes while their body is scanned. They will stand on a platform while a 3D scanner measures their body. They will have a test to measure how fast an electric signal moves through their body. They will grip an instrument to measure the strength of their hands. They will drink salty water and provide blood and urine samples. Participants may be invited to return for these 2-day visits up to 8 times per year. Return visits must be at least 2 weeks apart.

Neural and Psychological Mechanisms of Pain Perception

Background: \- Painful stimuli cause changes in a network of brain regions called the "Pain Matrix." But most of these regions respond to many other stimuli, not just pain. Researchers want to understand how different factors influence pain. They want to test what happens when people expect different levels of pain and receive treatments that can modify pain. They want to see if these factors influence decisions about pain and how the body responds to it. They also want to compare pain with responses like taste and vision. Objectives: \- To better understand how pain and emotions are processed and influenced by psychological factors. Eligibility: \- Healthy volunteers ages 18-50. Design: * This study requires 1 to 2 clinic visits that last 1 to 3 hours. * Participants will be screened with medical history and physical exam. * Some participants will have one or more magnetic resonance imaging (MRI) scans of their brain. For MRI, participants will lie on a table that slides in and out of a cylinder. The scanner makes loud knocking noises. They will get earplugs. * Participants' heart activity will be recorded with electrocardiogram. Their pulse, sweating, and breathing will be monitored. * Some participants will take a taste test. Others may perform simple tasks. Others may receive pain in their arm, leg, or hand. The pain will come from heat or electric shocks. Others may judge pain using a topical pain-relieving cream. Some of these tests may be given during MRI. * Participants will fill out questionnaires. * The study will last 3 years.

The Effects of Increasing Caloric Intake on Diet-Induced Thermogenesis and 24h Energy Expenditure

Background: Diet-induced thermogenesis (DIT) is the amount of energy one s body uses to eat food, absorb the nutrients from the food, and process those nutrients. Researchers would like to understand more about how changing the balances of protein, fat, carbohydrates, and total calories in the diet can affect DIT. Objective: To learn how different diets can change a person s DIT. Eligibility: Healthy people aged 18 to 60 years who have not intentionally lost weight in the past 6 months. Design: Participants will stay in a clinic for about 35 days. They will eat only the food provided. They will receive 8 different diets during the study, including 7 test diets. Participants will undergo multiple tests. They will be screened with blood and urine tests and a test of their heart function. During the first few days: Their waist, thigh, and neck circumference will be measured. They will have a DXA scan: They will lie on a padded table for about 20 minutes while an instrument measures the amount of fat in their body. They will be tested for diabetes. They will answer questionnaires about topics including eating behavior, hunger, and stress. Throughout the study: Their weight will be measured daily. Blood tests will be repeated. They will stay in a metabolic chamber a total of 9 times. They will remain in a closed room for 24 hours while researchers monitor the room temperature and levels of oxygen and carbon dioxide. Participants will collect all their urine for each 24-hour period. ...

Defining Neurobiological Links Between Substance Use and Mental Illness

Background: Nicotine dependence leads to about 480,000 deaths every year in the United States. People with major depressive disorder (MDD) are twice as likely to use nicotine compared to the general population. They have greater withdrawal symptoms and are more likely to relapse after quitting compared with smokers without MDD. More research is needed on how nicotine affects brain function in those with MDD. Objective: To understand how nicotine affects symptoms of depression and related brain function. Eligibility: People aged 18 to 60 years, at the time of consent, with and without MDD who do not smoke cigarettes or use other nicotine products. Design: Participants will have 2 or 3 study visits over 1 year. Participants will have 2 MRI scans no less than 4 days apart. Each scan visit will last 5 to 7 hours. At each scan, they will have urine and breath tests to screen for recent use of alcohol, nicotine, and illegal drugs. Before each scan, they will take 1 of 2 medications: nicotine or placebo. Participants will receive each medication once. They will not know which medication they are receiving at each scan. For each MRI scan, they will lie on a table that slides into a cylinder. Sometimes they will be asked to lie still. Sometimes they will complete tasks on a computer. Tasks may include identifying colors or playing games to win money. Each scan will take about 2 hours. Participants will answer questions about their thoughts, feelings, and behaviors before and after each scan. They will have a blood test after each scan.

Clinical and Scientific Assessment of Pain and Painful Disorders

Background: Researchers want to better understand pain by studying people with and without different kinds of pain. To do this, researchers will expose people to pleasant and unpleasant sensations. They will ask them questions about their pain. Researchers also want to see if these people are eligible for other research studies at the National Center for Complementary and Integrative Health. Objectives: To study the experience of pain. Also to find people eligible to join other NIH studies. Eligibility: People 12 years and older with and without pain disorders. Design: Participants will be screened by phone. Participants will have one required visit lasting about 2 hours. This may include: * Medical history * Physical exam * Questionnaires about themselves and their pain experience * Blood and urine tests * MRI: They will lie on a table that slides into a cylinder. They will feel different sensations while completing tasks on a computer. This lasts 15 minutes to 2 hours. * Quantitative sensory testing: They will be exposed to different pictures, sounds, tastes, and smells. They will also be exposed to pleasant and unpleasant sensations. These could include: * Burning, itching, or cold sensations * Pinpricks * Pressure and pinches * Electrocardiogram: Stickers on the chest record heart activity. * Straps placed around the chest to measure breathing. * Small sensors on the fingers or palms to measure pulse and sweating. Participants may have up to 12 other outpatient study visits. Participants may be recorded at the visits.

Energy Expenditure Responses to Different Temperatures

Background: \- The way that the body burns calories is known as energy expenditure. Some studies show that when we are cold, we burn more calories to keep our bodies warm. Brown fat is a special kind of fat that can use energy to keep the body warm. Small animals and infants have been known to have brown fat for many years. Recently, it has been suggested that adult humans also have brown fat. If brown fat becomes active (burns calories) in adult humans when exposed to cold, then these people would tend to burn off more calories and might not gain weight easily. Learning more about the relationship between energy expenditure, brown fat, environmental temperature, and body temperature may help explain why some people become obese and other people do not. Objectives: * To better understand how the body burns calories when exposed to different temperatures. * To study brown fat and how it burns calories in cold temperatures. Eligibility: * Healthy men between 18 and 35 or 55 and 75 years of age. * Healthy women between 18 and 35 years of age. * To control for ethnicity, participants must be non-Hispanic whites or African Americans. Design: * Participants will be screened with a physical exam and medical history. Blood and urine samples will be collected. * Participants will stay in the Metabolic Unit of the National Institutes of Health Clinical Center as inpatients for no more than 14 days. The length of the hospital stay will depend on how participants respond to the different study temperatures. * Every afternoon, participants will walk for 30 minutes on a treadmill. All meals will be provided. * Participants will stay up to 5 hours per day in a specialized room with different temperature settings. Temperatures will range from about 61 degrees to 88 degrees Fahrenheit. Body temperature, activity, calorie burning, and cold/hot sensations will be monitored. On the study day of the coldest temperature, participants will have an imaging study to look for brown fat activity. * Participants will be compensated for their time and participation at the end of the study.

Influence of Brain Oscillation-Dependent TMS on Motor Function

Background: When people have a stroke, they often have difficulty moving their arms and hands. Transcranial magnetic stimulation (TMS) can improve how well people with and without stroke can move their arms and hands. But the effects of TMS are minor, and it doesn t work for everyone. Researchers want to study how to time brain stimulation so that the effects are more consistent. Objective: To understand how the brain responds to transcranial magnetic stimulation so that treatments for people with stroke can be improved. Eligibility: Adults ages 18 and older who had a stroke at least 6 months ago Healthy volunteers ages 50 and older Design: Participants will have up to 5 visits. At visit 1, participants will be screened with medical history and physical exam. Participants with stroke will also have TMS and surface electromyography (sEMG). For TMS, a brief electrical current will pass through a wire coil on the scalp. Participants may hear a click and feel a pull. Muscles may twitch. Participants may be asked to do simple movements during TMS. For sEMG, small electrodes will be attached to the skin and muscle activity will be recorded. At visit 2, participants will have magnetic resonance imaging (MRI). They will lie on a table that slides into a metal cylinder in a strong magnetic field. They will get earplugs for the loud noise. At visit 3, participants will have TMS, sEMG, and electroencephalography (EEG). For EEG, small electrodes on the scalp will record brainwaves. Participants will sit still, watch a movie, or do TMS. Participants may be asked to have 2 extra visits to redo procedures.

Functional Magnetic Resonance Imaging Sleep Study With Auditory Stimuli

Background: An electroencephalogram (EEG) measures the brain s electrical activity. EEG shows that the louder the sound needed to wake a person, the deeper the person s sleep. Researchers are using functional magnetic resonance imaging (fMRI) to study people during sleep so they can view brain activity in 3D. But they still need to correlate fMRI with sound thresholds, like the EEG. Objective: To measure brain activity during sleep using fMRI and EEG. Eligibility: Healthy people ages 18 34 who can sleep on their back for several hours. Design: Participants will be screened online about their sleep and general health. At a screening visit, participants will have: Physical exam Hearing exam MRI scan. A strong magnetic field and radio waves take pictures of the brain. Participants will lie down on a bed that slides into the scanner, which is shaped like a cylinder. Participants will wear an actigraph on their wrist that records their motor activity. Participants will follow a 2-week routine. This includes regular in-to-bed and out-of-bed times and limits on alcohol, caffeine, and nicotine. During the overnight visits, participants will have: Female subjects will have a urine pregnancy test. fMRI. A coil will be placed over the head. Participants will do tasks shown on a computer screen inside the scanner. EEG. Small electrodes on the scalp will record brain waves while sleeping or doing a task in the scanner. Participants will be asked to try to sleep while researchers collect fMRI and EEG data. Participants eyes will be monitored with a video camera. Headphones will deliver sounds to wake them up throughout the night. ...

Assessing and Improving Quantitative Magnetic Resonance Imaging Metrics in Human Subjects

Background: Magnetic resonance imaging (MRI), which uses strong magnets to get images of structures inside the body, is a valuable tool in modern medicine. But researchers are always looking for ways to improve this technology. To better understand how to use MRI to diagnose problems, researchers need to collect more data from scans of healthy people. Objective: To get MRI scans of healthy people to improve the measurements doctors can make from the images. Eligibility: People aged 18 years or older in good general health. Design: Participants will be screened. They will have a physical exam focused on their nervous system. They will complete questionnaires. Participants will have at least 1 MRI scan. The target of the scan may be the brain, liver, prostate, breast, or other body part. Before the scan, participants will remove any metallic objects. They will lie on a narrow table that moves into a long, narrow tube. They may have special pads placed around them to help them remain still. Participants will hear loud noises during the scan. They will get earplugs or earmuffs to wear to muffle the sound. They can communicate with the MRI technician and will have an emergency button to squeeze at any time if they want the scan to stop. The scan will take up to 2 hours. Some participants may be asked to perform tasks on a computer screen during the scan. Participants may return for up to 5 scans in 3 months. Some may have as many as 30 MRI visits per year. They may remain in the study for up to 2 years.

Investigational Use of Neuromuscular Ultrasound

Background: Current techniques used to measure the health and function of a person s nerves and muscles are generally effective, but they do have limits. Researchers are looking for ways to improve the ability to observe nerves and muscles and how they function in this natural history protocol. Objective: To study the use of ultrasound (sound waves) to learn more about nerves and muscles. Eligibility: Healthy adults, aged 18 and older, with no history of stroke, nerve or muscular disorders, or spine surgery are also needed. A smaller population of adults aged 18 and older who have a neuromuscular disorder or show symptoms of nerve or muscle disorder will also be evaluated. Design: Participants will be screened with a medical record review. Participants will have up to 5 outpatient clinic visits. Most participants will have 1 or 2 visits. Visits will last for less than 3-4 hours each. During each visit, participants will give a brief medical history and have a physical exam. Participants will have ultrasounds to get pictures and measurements of their nerves and muscles. Gel will be applied to their skin. A probe will be placed on the skin surface. Sound waves sent through the probe will be used to create pictures. Participants may have nerve conduction studies. Wires will be taped to the skin surface near a muscle or nerve in the arm or leg. The nerve will be stimulated with a small electric current that feels like a rubber band flick. The response will be recorded through the wires.