Clinical Research Directory

Wearable tDCS and Acute Golf Shot Performance

Transcranial direct current stimulation (tDCS) has been investigated as an ergogenic aid for two decades, but most sport evidence comes from laboratory stimulators operated by experimenters. This trial evaluates whether a single 20-minute session of wearable, app-controlled bilateral motor-cortex tDCS (Halo Sport 2, 2 mA) improves full-swing golf shot performance compared with sham stimulation. The study is a double-blind, sham-controlled, parallel-group randomized trial with a pre-test/post-test design in golfers stratified into professional, amateur-high, and amateur-middle skill groups. Each participant attends a single session comprising a 40-shot pre-test, 20 minutes of real or sham stimulation, and a 40-shot post-test, with shots measured by a TrackMan 4 launch monitor across eight standardized club categories. The primary outcomes are change scores (post minus pre) in carry distance, ball speed, smash factor, within-player carry-distance variability, and absolute lateral deviation. Effects will be examined overall and as a function of skill level (categorical group and continuous golf handicap).

Positron Emission Tomography (PET) Imaging of Reactive Oxygen and Nitrogen Species: Human Observation of Retention and Safety of [18F]-Fluoroedaravone

This first-in-human research study will test the safety of a new PET imaging tracer called\[18F\]fluoroedaravone (\[18F\]FEDV) in healthy adults. Participants will receive one injection of the tracer and undergo several PET/CT scans over about 3 hours. Researchers will collect blood and urine samples, check vital signs and heart activity (ECGs), and ask participants about any symptoms to learn how the tracer moves through and leaves the body and to monitor for side effects. Information from this study will help researchers develop this imaging tracer for future studies of oxidative stress, a process linked to inflammation and long-term health problems in cancer survivors and other diseases. Primary Objective(s): • Generate safety data and calculate biodistribution and organ dosimetry in healthy adult volunteers following \[18F\]fluoroedaravone intravenous administration.

Effects of Urolithin A Supplementation on Glucose Metabolism in Healthy Adults 55 >= Years Old: A Randomized Triple-Masked Controlled Clinical Trial

Background: As people age, the cells in the pancreas that produce insulin begin to release less of this hormone, and levels of blood glucose (sugar) rise. This can lead to illnesses such as diabetes. Urolithin A (UA) is a natural nutritional supplement that may improve how the body controls blood glucose. Objective: To learn if UA improves levels of insulin and other hormones that help control blood glucose. Eligibility: People aged 55 years and older with a body mass index of 27 or higher. Design: Participants will have 6 clinic visits over 8 weeks. Participants will be screened. They will have a physical exam with blood and urine tests and a test of their heart function. UA gelcaps are taken by mouth every morning at home. Half of participants will take UA. The other half will take a placebo. The placebo looks like the study drug but does not contain any medicine. Participants will not know which they are taking. Participants will have tests during the study including: Oral glucose tolerance: Participants will drink a sweet liquid. Blood will be drawn at intervals over the next 3 hours. Continuous glucose monitor: A sensor with a needle that goes just under the skin will be placed on the upper arm. Participants will wear this sensor throughout the study. Exercise. Participants will walk on a treadmill while their heart rate, hearth rhythm, and blood pressure are monitored. They will walk in a hallway at normal and fast paces. Imaging scans of the thigh; scans of the brain are optional....

Discovering Determinants of Food Intake by Application of Artificial Intelligence to Complex, High-Dimensional Data

Background: Many people in the United States are overweight or obese. Researchers want to learn why some people can overeat and not gain weight, whereas others who do not overeat still gain weight. Objective: To study factors related to food intake that can lead to weight gain over time. Eligibility: Healthy adults aged 18 to 60 years. Design: Participants will have 6 to 8 clinic visits over 2 years. The first 3 or 4 study visits will be 1 week apart. Procedures during visits may include the following: Collection of blood, hair, urine, and stool samples. Measurement of the waist, neck, thighs, and other parts of the body. Dual energy x-ray absorption (DXA) scan: Participants will lie still on a padded table while they are scanned to measure body fat. Physical activity monitor: Participants will wear a monitor on the wrist for 2 weeks. Cognitive tests: Participants will perform tasks to measure attention, memory, and brain function. Continuous glucose monitor. Participants will wear a device that measures their blood glucose for 1 week. Mixed meal test and stomach emptying test. Participants will drink a breakfast shake and swallow a dose of acetaminophen. Blood will be drawn over the next 4 hours. Resting metabolic rate: Participants will wear a clear hood over their head while they rest for 20 minutes. The hood will measure the gases they breathe. Breakfast and lunch test. Participants will eat a standard breakfast. They will be allowed to select from foods and eat as much as they like at lunch. They will be asked how hungry or full they are. Questionnaires. Participants will answer questions about their health, sleep, physical activity, and eating.

Positron Emission Tomography and Organ-Specific Changes in Participants Co-Enrolled in NIH Studies of Plasmodium Vivax Controlled Human Malaria Infection

Background: Malaria is a serious disease caused by parasites spread by mosquitoes. To better diagnose and treat malaria, researchers need to learn more about where the parasites go when they enter a person's body. They want to see if they can locate the malaria parasites in the body using imaging scans. Objective: To learn whether imaging scans can locate parasites in people with malaria. Eligibility: Healthy people aged 18 to 54 years. They must be enrolled in protocol IRB001970 or IRB002627 for controlled malaria infection. Design: Participants will be screened. They will have blood drawn and a physical exam, including an abdominal exam to check the size of their spleen. Participants for this study will have 2 or 3 positron emission tomography/computed tomography (PET/CT) scans: The first will be about 3 days before they are deliberately infected with malaria for a different study. The second will be about 13 days later, while they have the disease. The third scan is optional; it will be done about 3 and 1/2 weeks after the second scan. For each scan, participants will receive a radioactive tracer called fluorodeoxyglucose (FDG). FDG will be injected through a tube inserted into a vein. They will lie on a table that slides through a doughnut-shaped machine. PET/CT uses x-rays to create images of the inside of the body. All participants will have a follow-up visit about 3 and 1/2 weeks after the second scan. The blood draw and physical exam will be repeated. This visit may be combined with the third scan for those who choose it.

Effects of Meal Macronutrients on Postprandial Lipids

Background: Abnormal fats in the blood can lead to many problems, including heart disease. Researchers want to learn more about how eating meals with different levels of nutrients affects fats in the blood. Specifically, they want to study people with too much body fat, too little body fat, and a kidney problem called nephrotic syndrome. Objective: To learn more about how different types of foods affect fat levels in the blood. Eligibility: People aged 18 years or older with a health condition that affects how their body handles fats. Healthy volunteers are also needed. Design: Participants will have 2 overnight stays in the clinic within 6 months. At each visit, after staying overnight, they will eat a breakfast casserole. At 1 visit, breakfast will be a high-fat, low carbohydrate meal. At the other, it will be a high-carbohydrate, low-fat meal. Participants will have a tube inserted into a vein in their arm. They will have blood drawn via the tube 12 times in 8 hours: 2 times before they eat the breakfast and 10 times after. Participants will have other tests during their stays: * A resting metabolic test captures the air they exhale and measures how much energy they use at rest. * A dual energy X-ray absorptiometry (DXA) scan measures how much fat and muscle they have. * A Fibroscan is a special type of ultrasound of the liver. * A body surface scan uses lasers to measure the total area of the body. * A bioelectric impedance (BIS) exam measures how fast small electric currents move through their body. Participants may opt to have a third visit. At this visit, the breakfast will be high in protein....

Assessing the Impact of Perceptions of Unpredictability on Objective Measures of Food Consumption and Metabolism

Background: Many people in the United States are overweight or obese. This natural history study will look into how life events during childhood can impact eating behaviors and weight gain as adults. Objective: To explore how childhood experiences affect adult eating behaviors. Eligibility: Healthy people aged 18 to 60 years. Design: Participants will have 3 clinic visits. They will be screened with blood tests. They will answer questions about their alcohol and tobacco use. At the next visit, participants will undergo these activities: Parts of their body (such as waist, neck, and thighs) will be measured with a tape. They will have an imaging scan to find out how much body fat they have. They will start wearing a device like a wristwatch that measures their physical activity. They will wear this device for up to 10 days. They will wear a device on their upper arm or belly that measures blood glucose (sugar) levels. Participants will wear this for 7-10 days. They will answer questions about their education, childhood, and routines. They will receive a kit to collect a stool sample at home. At the last visit, participants will have these tests: Participants will relax and breathe normally while wearing a clear, plastic canopy that fits over their entire head. Blood samples will be taken before and after participants drink a sugary drink. Participants will be offered a large selection of foods for lunch. They will eat as much as they want. Then they will answer questions about how they feel about food and themselves.

A Study to Learn How ASP3082 is Processed in Healthy Men

Setidegrasib (ASP3082) is being developed for certain cancers. In this study, the researchers want to understand how it is processed by the body in healthy male volunteers. To do this, \[14C\] which is a certain chemical (called a tracer, or radionuclide) has been added to setidegrasib. \[14C\] gives off radiation, but the dose is very low (about the same as the dose from an x-ray) and will leave the body within a few days. \[14C\] will be picked up by a scanner and will be used to follow setidegrasib through the body. \[14C\]setidegrasib will be given as 1 single injection slowly through a vein (infusion). The men will stay overnight in the clinic for at least 2 weeks. They will give regular blood, urine and stool samples during their stay and will be closely monitored. The men will return to the clinic about 1 week later for a final safety check.

Pharmacokinetics of Antituberculosis Drugs in Breastfeeding Women

This study is a sub-study of the SSTARLET trial (NCT06498414). The overall aim is to assess the pharmacokinetic profiles after taking a single dose of rifampicin, isoniazid, levofloxacin, rifapentine, and bedaquiline in breastfeeding women and the excretion of these drugs in breast milk, with the hope of including breastfeeding women in future clinical trials of TPT, including expanding the inclusion criteria of the SSTARLET trial. In this study, healthy breastfeeding women who fulfill the eligibility criteria will be enrolled from several primary health care centers in Bandung, which will be referred to the TB Research Clinic of the Universitas Padjadjaran, Bandung, Indonesia. Ten participants will be randomized to each of the following six study arms: * Arm A: Single-dose rifampicin at 10 mg/kg body weight (RIF10). * Arm B: Single-dose rifampicin at 20 mg/kg body weight (RIF20). * Arm C: Single-dose isoniazid at 5 mg/kg body weight (INH5). * Arm D: Single-dose levofloxacin at 10-15 mg/kg body weight (LFX10-15). * Arm E: Single-dose rifapentine at 10 mg/kg body weight (RPT10). * Arm F: Single-dose bedaquiline at 400 mg (BDQ400).

Visual Attention, Object Recognition, and Eye Movements in Healthy Volunteers

Background: Vision is vital for many of our daily activities. Researchers want to learn more about how we aim our eyes (that is, what images, such as faces, immediately attract our attention) and how we direct our attention (that is, what we see and what we ignore). Objective: To study how healthy adults process and respond to visual images. Eligibility: Healthy people aged 18 years with no vision problems. Design: Participants will have 5 to 10 clinic visits over 2 to 4 months. Some participants may have up to 25 visits. Each visit lasts about 1 hour. Participants will be screened. They will answer questions about their medical and eye history. They will have a standard eye exam; eye drops will be used to dilate the pupils. (They may skip this exam if they have had an eye exam at the NIH within the past year.) Participants will perform eye movement tests. They will sit in front of a computer and view images that appear on the screen. They may be asked to respond to what they see by speaking, moving their hands, looking in a certain direction, or pushing a button. Their eye movements will be tracked. For some tests, participants heads may be held steady using a chinrest and head strap. For some tests, they may wear a cap fitted with cameras that use invisible lights in front of their eyes.

Vaccine Responses to SARS-CoV-2 and Other Emerging Infectious Diseases

Background: Vaccines against SARS-CoV-2, the virus that causes COVID-19, have been highly effective against preventing severe disease. But the protective effects of these vaccines appear to wane over time. Researchers want to learn why. Objective: To learn more about how the immune system responds to vaccines against infections like SARS-CoV-2. Eligibility: Healthy adults ages 18 or older who are scheduled to receive either a new vaccine or a booster shot against SARS-COV-2 or another emerging infection. Design: Participants will be screened with a medical history and blood and urine tests. Participants will have up to 8 study visits in 1 year. Each visit should last less than 2 hours. At each visit, participants will give blood samples. Some blood samples will be used for genetic testing. They will also give updates on their health. After the first study visit, participants will receive either a first vaccination or a booster shot. They must get the vaccine in their community or workplace. They will not get the vaccine at NIH. This study currently focuses on SARS-CoV-2, but it will expand to other infectious diseases as they emerge and become the target of new vaccines. ...

Collection of Peripheral Blood Mononuclear Cells (PBMCs) From Healthy People for the Expansion of T Cells for Adoptive Cell Therapy

Title: Collection of Peripheral Blood Mononuclear Cells (PBMCs) from Healthy People for the Expansion of T Cells for Adoptive Cell Therapy Background: New therapies are being developed that use a person s own immune system to fight tumors. Some of the tumors being studied include cancers caused by viruses. Researchers want to use the healthy cells of volunteers to perform research studies. To do this, they are collecting lymphocytes through leukapheresis. Objectives: To collect healthy cells from volunteers for research studies for new cancer therapies. Eligibility: Healthy people ages 18 and older Design: Participants will be screened with a standard donor questionnaire. It asks about their health and past medical problems. It also asks about risky behaviors that could increase their exposure to viruses or bacteria that could be transmitted through a transfusion. Participants will give a blood sample to make sure they are able to donate. They will have a physical exam. A finger stick test will check their hemoglobin, or red blood cell, level. They might give a urine sample. Participants will undergo apheresis. For this, a needle is placed in a vein in each of their arms. Their blood is taken from one arm. A machine separates the white cells from the red cells and plasma by a spinning process. The white cells are removed and directed into a plastic bag. The red cells and plasma are returned through the needle in the other arm. The entire procedure takes 4 6 hours. Participants may donate every 21 days in this protocol if they choose to.

Role of Metal Ion Transporter ZIP8 in Alcohol-Related Behaviors

Background: Alcohol use disorder (AUD) can damage people s health, work, and family. Researchers want to know more about why some people are more vulnerable to AUD than others. The ZIP8 gene may be linked to an increased risk of AUD. Researchers want to find out how different forms of the ZIP8 gene affect how healthy people drink alcohol and how alcohol affects their brain. Objective: To study how genes may affect how people drink alcohol and how it affects their brain. Eligibility: Healthy people aged 21 to 60 years. They must not smoke, and they must have no history of AUD. They must have European ancestry and be enrolled in Natural History Protocol (14-AA-0181). Design: Participants will have 2 study visits. At the first visit, participants will be given alcohol; it will be infused through a tube attached to a needle inserted into a vein. They may self-administer each dose by pressing a button. Over time, they will have to press the button an increasing number of times to receive more alcohol. The infusion period will last 2.5 hours. Participants will have blood samples taken and breath measurments, and they will do computer tasks and complete questionnaires during and after the infusion. After the infusion, they will remain in the clinic until their breath alcohol levels drop to a safe level. At the second visit, participants will have an imaging scan of their brain. They will do tasks and play games on a computer screen during the scan. Some participants may have an extra visit for screening. A mid-study visit may also be needed if more than 6 months pass between the 2 study visits.

Study of New Magnetic Resonance Imaging Methods of the Brain

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. ...

Neuropharmacologic Imaging and Biomarker Assessments of Response to Acute and Repeated-Dosed Ketamine Infusions in Major Depressive Disorder

Background: Most medications that treat depression take weeks or months to work. Researchers want to develop fast-acting treatments. One dose of ketamine has a rapid antidepressant effect. For most people, this lasts a week or less. Repeated doses of ketamine may help maintain this effect. Objective: Main Study: To study the effects of ketamine in treating depression. Ketamine Metabolites Substudy: To study how ketamine effects brain chemistry. To study how ketamine effects the brain. This is done by looking at metabolites, which are created when a drug is broken down. Eligibility: Main Study: People ages 18-65 with major depressive disorder and healthy volunteers Ketamine Metabolites Substudy: Healthy volunteers ages 18-65 Design: Main Study: Participants will be screened in another study, with: * Medical and psychiatric history * Psychiatric and physical exam * Blood, urine, and heart tests Participants will be inpatients at NIH for 4 phases totaling 14-20 weeks. Phase I (2-7 weeks): * Gradually stop current medications * MRI: Participants lie and perform tasks in a machine that takes pictures of the body. * Mood and thinking tests * Blood and urine tests * Sleep test: Monitors on the skin record brain waves, breathing, heart rate, and movement during sleep. * Transcranial magnetic stimulation: A coil on the scalp gives an electrical current that affects brain activity. * Stress tests: Electrodes on the skin measure reactions to loud noises or electric shocks. Phase I tests are repeated in Phases II and III and in the final visit. Phase II (4-5 weeks): * 4 weekly IV infusions of ketamine or a placebo during an MRI or MEG. For the MEG, a cone over the head records brain activity. Phase III (optional): * 8 infusions of ketamine over 4 weeks Phase IV (optional): * Symptoms monitoring for 4 weeks * Participants will have a final visit. They will be offered standard treatment at NIH for up to 2 months. Ketamine Metabolites Substudy: Participants will be screened in another study, with: * Medical and psychiatric history * Psychiatric and physical exam * Blood, urine, and heart tests Participants will be inpatients at NIH for 4 days. Study Procedures: Mood and thinking tests Blood and urine tests 1 infusion of ketamine Spinal tap and spinal catheter: Used to get samples of cerebrospinal fluid (CSF). This is a fluid that moves around and within the brain and spinal cord. Studying CSF will help us learn how ketamine effects brain chemistry ...

Impact of Force Feedback in VR Training on EEG Biomarkers and Real-World Motor Performance

The goal of this interventional study is to learn how force feedback in virtual reality training affects electroencephalography (EEG) biomarkers and/or real-world motor performance. The main question it aims to answer is: ● How does physical training compared to virtual reality training with force feedback compared with virtual reality training without force feedback affect EEG biomarkers and/or motor performance? Participants will: * Have baseline EEG measurements taken before, during, and after participation in either a physical or virtual training activity. * Participate in the selected training activity they have been randomly assigned to (either physical, virtual with force feedback or virtual without force feedback) * For both VR training groups, they will have their motor performance measured performing the real world physical activity once they have completed the training activity. This will function as a transfer task.

Screening for Hematology Branch Protocols

This study allows the evaluation of subjects in order to determine their ability to safely participate in other active research studies. After subjects complete the screening process, they will be offered the opportunity to participate in an active research study, or if no appropriate studies are available information and recommendations will be provided for other treatment options....

Turkish Validity and Reliability of VRSUQ

The aim of this study is to conduct a Turkish validity and reliability study of the Virtual Reality System Usability Questionnaire (VRSUQ), which can evaluate virtual reality from various aspects by taking into account the characteristics of virtual reality and usability evaluation indicators.

The Acquisition of Blood and Skin Samples From Normal Volunteers to Support Research Activities on Dermatologic Diseases

Background: -This protocol is concerned with the acquisition of blood, skin, or mucosal samples from healthy volunteers or patients with selected skin diseases to support the basic science and clinical research activities of the Dermatology Branch and other intramural Laboratories and Branches at the NIH Clinical Research Center. Objectives: (Primary) -To allow collection of blood, skin, or mucosal samples from healthy volunteers or patients with selected skin or systemic diseases as needed to support the research activities of our Branch and other Laboratories and Branches. Eligibility: * Healthy individuals (including employees and other patients) and patients with selected skin or other diseases, including individuals of both genders and all racial/ethnic groups. * Patient volunteers must be willing to undergo blood drawing and/or skin/mucosal biopsies. Design: -This is dependent upon the particular investigation for which these samples are needed....

Novel Biomarkers of Non-IgE Immediate Hypersensitivity Drug Reactions

The goal of this clinical trial is to investigate biomarkers of non-IgE-mediated immediate hypersensitivity reactions during infusion of intravenous vancomycin. The main question it aims to answer is: • Identifying novel biomarkers in blood that occur during infusion reaction Participants will: * Have allergy skin testing for vancomycin * Receive an infusion of vancomycin

Characterization of Diseases With Salivary Gland Involvement

Background: \- Salivary glands in and around the mouth and throat make saliva. Salivary gland disorders can affect a person s quality of life. Studying people who have a disease that affects their salivary gland(s) may teach researchers about the disorders and their genetics. Objectives: \- To study salivary gland diseases and disorders. To collect data and samples from people with salivary gland problems and their relatives. Eligibility: * People more than 4 years old who have or are suspected to have a disease involving salivary glands. * Their relatives more than 4 years old. * Healthy volunteers 18 years or older. Design: * Participants may be screened with: * Medical history * Physical exam * Blood and urine tests * General oral and dental history and exam * Saliva collection * Eye exam and test for dry eyes * Health questionnaires (adults) * Biopsy of some minor salivary glands. A small incision will be made on the inside of the lower lip and several tiny salivary glands will be removed. * Participants will have 2-3 visits. These may include: * Repeats of some screening tests * Ultrasounds of some glands. Researchers will put some gel on the face, then press on it with a smooth wand. * Adults may have other biopsies * A small catheter inserted into the opening of the parotid gland duct on the inside of the cheek. A saline solution (in a syringe) will fill the duct. * Swishing a saltwater solution in the mouth for 10 seconds and then spitting into a cup * Scrapings collected from teeth, tongue, and cheeks

Oral Bacteria and Immune System Problems Involved in Gum Disease (Periodontitis)

Background: \- Gum disease is a condition in which the tissue around the tooth root becomes swollen and infected. This condition can cause tooth loss if it is not treated. Who gets gum disease and how bad it will be depends on (1) the different bacteria in the mouth and (2) how the immune system of an individual handles these bacteria. Researchers want to look at the oral bacteria and genetic immune problems of different people to learn how these affect gum disease and other conditions of the mouth. Objectives: \- To study how immune system problems may lead to problems in the mouth, including gum disease. Eligibility: * Children and adults at least 7 years of age who have genetic problems with their immune system. * Healthy adults that have periodontal disease * Health adults that do not have periodontal disease Design: * This study will involve a screening visit and a study visit. * Participants will be screened with a medical history, blood work and a full oral and dental exam, including dental x-rays and photos. * The study visit will involve collection of blood, urine, and other samples, including saliva, plaque, and gum swabs. Any abnormal tissue will sampled for a biopsy. Additional oral and dental exams will be performed. Participants will also answer questions about any current medical or dental problems.

NEURO-IS: Neurophysiology of Inner Speech Across Neurotypical Participants.

The purpose of this study is to investigate the brain activity associated with two common inner experiences: visual mental imagery (mentally seeing objects or actions) and inner speech (experiencing language without speaking out loud). Researchers aim to identify the most effective tasks to generate robust and detectable brain signals (EEG biomarkers) for these experiences in healthy adults. Participants will complete questionnaires and perform specific mental tasks, such as silently repeating words or imagining movements and faces, while their brain activity is recorded using high-density electroencephalography (hdEEG). These tasks will be compared to resting and passive listening conditions to better understand the relationship between inner experiences, self-awareness, and neurophysiology.

A Study to Learn About the Safety of BIIB115 Injections and How BIIB115 is Processed in the Bodies of Healthy Adult Male Volunteers and of Pediatric Participants With Spinal Muscular Atrophy Who Previously Took Onasemnogene Abeparvovec

In this study, researchers will learn about a study drug called BIIB115 in healthy adult male volunteers and in participants with spinal muscular atrophy (SMA). This study will focus on children with SMA. The main objective of the study is to learn about the safety of BIIB115 and how participants respond to different doses of BIIB115. The main question researchers want to answer is: • How many participants have adverse events and serious adverse events during the study? Adverse events are unwanted health problems that may or may not be caused by the study drug. Researchers will also learn about how the body processes BIIB115. They will do this by measuring the levels of BIIB115 in both the blood and the cerebrospinal fluid, also known as the CSF. This is the fluid around the brain and spinal cord. The study will be split into 2 parts - Part A and Part B. During Part A: * After screening, healthy volunteers will be randomly placed into 1 of 4 groups to receive either BIIB115 or a placebo. A placebo looks like the study drug but contains no real medicine. * Participants will receive a single dose of either BIIB115 or the placebo as an injection directly into the spinal canal on Day 1. * Neither the researchers nor the participants will know if the participants will receive BIIB115 or the placebo. * The Part A treatment and follow-up period will last for 13 months. * Participants will have up to 6 clinic visits and 4 phone calls. During Part B: * After screening, children with SMA will be placed into 1 of 2 groups to receive BIIB115. * The doses of each group will be decided based on the results of Part A. * Both researchers and participants will know they are receiving BIIB115. * Participants will first receive 2 total doses of BIIB115 given at 2 different times. * The Part B treatment and follow-up period will last for 24 months. * Participants will have up to 14 clinic visits and 6 phone calls. Part B Long-Term Extension: * After completing the 25 months in Part B, participants may move onto the long-term extension (LTE). * They will receive 5 more doses of BIIB115 at different times. * The Part B LTE treatment and follow-up will last for 60 months. * Participants will have up to 12 more clinic visits and 19 phone calls. In both Part A and Part B, participants will stay in the clinic for 24 hours after each dose so that researchers can check on their health. This 24-hour stay will not be required for the Part B LTE period.