View clinical trials related to Normal Physiology.
Filter by:Background: Transcranial magnetic stimulation (TMS) of the brain has been used to change the activity and connections in the brain to improve memory. Researchers are interested in how these brain changes cause memory improvements and how activity at the time of stimulation may change the effects of TMS. Objective: To learn how brain stimulation can be used to improve memory. Eligibility: Healthy adults ages 18-40 Design: Participants will be screened with a medical record review. Participants will have 3 study visits. At visit 1, participants will have a physical exam and will talk about their health. They will have magnetic resonance imaging (MRI). The MRI scanner is a metal cylinder surrounded by a strong magnetic field. During the MRI, participants will lie on a table that can slide in and out of the scanner. A coil will be placed over the head. Participants will be asked to keep their eyes focused on a small cross on a computer screen inside the scanner. The scanner makes loud noises. Participants will get earplugs. At visits 2 and 3, participants will have TMS and perform tasks. For TMS, a wire coil encased in plastic is held on the scalp. When the coil is triggered, a brief electrical current passes through the coil and creates a magnetic pulse that stimulates the brain. During TMS, an electroencephalogram (EEG) will record brain activity. For the EEG, a cloth cap with electrodes is fitted on the participant s head. Participants will complete a memory task and a spatial processing task. They will also complete surveys about their mental state. Participation will last 2-3 weeks. ...
Background: 'Free will' can be defined as the belief that people have control over their thoughts and movements. The topic of free will is controversial and is still being debated. Science has only partial answers to questions about free will, so researchers want to learn more about it. They want to assess the role of consciousness when intentions are present with behavior. This could help to explain the causal role of consciousness in movement or decisions. Objective: To learn more about free will. Eligibility: Healthy, right-handed adults ages 25-45 Design: Participants will be screened with medical history, physical exam, and neurological exam. Participants will have 1 study visit. It will last up to 4 hours. Participants will sit in a comfortable chair in front of a screen. They will perform some or all of the following tasks. Visual Task. Participants will watch different stimuli on the screen and answer simple questions. Electroencephalography (EEG). An EEG records the electrical activity of the brain ('brain waves'). For the EEG, small electrodes are put on the scalp with an electrode cap. A gel is placed in the space between the electrodes and the scalp. Participants' brain waves will be recorded, including while they decide whether to move their thumb. Choice/Reaction Time Task. Participants will watch different stimuli on the screen and react to them by moving their wrist. During this task, they will wear an EEG cap on their head and electrodes on their arms and wrists. Electromyography. Small electrodes will be attached to participants' skin. Their muscle activity will be recorded while they decide whether to move their wrist and during the movement itself. Transcranial Magnetic Stimulation (TMS): TMS is a non-invasive brain stimulation that uses magnetic field to stimulate nerve cells in your brain. TMS can increase or decrease brain activity in particular area of your brain. TMS operates completely outside of the body and is generally very well tolerated....
Background: Much is known about how people perceive light touch, temperature, and pain. But less is known about how deep pressure is perceived. Deep pressure is an important part of many touch therapies, like massage therapy. Researchers want to learn more to help people with chronic pain and other disorders. Objective: To find out which sensory nerve fibers are involved in feeling the sensation of deep pressure. Eligibility: Healthy people ages 18 50 enrolled in study number 16-AT-0077 Design: Participants will be screened under study number 16-AT-0077 Participants will have 1 visit that lasts about 2 hours. Participants will have a brief medical interview. They will have a urine test. Participants will have ischemic nerve block on 1 arm. A blood pressure cuff will be inflated until the arm is numb for up to an hour. Participants will have tests to see how they perceive different sensations. They will rate gentle brushing on the hands and forearms. They will rate gentle pressure squeezing from a hand massager on the hands and forearms. Participants will receive other sensations such as vibration, cool, warm, pinprick without piercing the skin, finger movement, and pressure. They will be asked to rate or respond to the sensations. They will be asked to rate any pain or discomfort from the nerve block on an ongoing basis.
Background: People tend to pay more attention to one side of space than the other and this may be due to differences in the structure and function of the two sides of the brain. We are interested in whether we can detect those difference with magnetic resonance imaging (MRI), transcranial magnetic stimulation (TMS), and electroencephalography (EEG). Objective: The purpose of the study is to understand how differences in brain structure may cause people to pay more attention to one side than the other. Eligibility: Healthy adults ages 18-35 Design: Participants will be screened with a neurological exam. Participants will have 2-3 visits for a total duration of about 7/8 hours. Women of childbearing age must have a negative pregnancy test before each MRI scan. Visits may include: Physical exam Tests of attention, and thinking TMS. A brief electrical current will pass through a wire coil on the scalp. Participants will hear a click and may feel a pull. They may be asked to tense muscles or do tasks. Magnetic resonance imaging (MRI) scan for a maximum of 1 hour. Participants will lie on a table that slides into a cylinder in a strong magnetic field. They will do tasks on a computer screen or lie still. They will get earplugs for loud noise. EEG for no longer than 5 hours, with most lasting 3 hours. Gel and a cap with electrodes will be placed on the scalp. They will record brain waves while the participant gets TMS or does nothing. Questions about participants dominant hand and about the MRI.
Background: Dopamine (DA) is a chemical signal in the brain linked to learning, memory, and habits. Stimulant drugs like methylphenidate can increase DA in the brain. Researchers want to measure DA with and without this drug. They want to learn how methylphenidate and brain dopamine affect body responses, mood, and thinking. Objective: To better understand the role of dopamine in the brain and the effects of methylphenidate. Eligibility: Adults ages 18-55 who have used alcohol or stimulant drugs but have no drug dependence. Design: Participants will be screened with: - Physical exam - Question about medical, psychiatric, and alcohol and drug use history - Questions to see if it s safe to have a PET/MRI scan - Blood and urine tests - Breath test for alcohol Participants will have 3 or 4 study visits. At each visit they will have: - Urine and breath tested for alcohol and drugs - A thin plastic tube (catheter) inserted in each arm by needle - A small amount of radioactive chemical injected through the catheter. - PET/MRI scan. Participants will lie still on a table that slides in and out of a metal cylinder surrounded by a strong magnetic field. Their vital signs will be monitored. They will get earmuffs for loud noises. Before the scan, participants will get the study drug or placebo through the catheter. They may also get a sugar pill (placebo). They will get a small meal and have blood drawn. - Tests of memory, attention, and thinking. Participants will wear an activity monitor on the wrist for one week.
Background: A radioligand is a radioactive substance that is used to diagnose diseases. A new ligand is called [11C]PS13. This has a small amount of radioactivity that can be detected by a positron emission tomography (PET) scan. If this ligand works well in this study, researchers may be able to use it to better understand and diagnose brain disorders. Objectives: To evaluate if [11C]PS13 can measure its receptor, which is involved in inflammation. To see if researchers get the same results when scanning a person twice. Eligibility: Healthy people ages 18 and older who are in Protocol 01-M-0254. Design: This study requires three visits of 2-5 hours each. Participants will have 2 PET scans with [11C]PS13. A needle will guide a small plastic tube (catheter) into an arm vein. The needle will be removed, leaving only the catheter in the vein. The ligand will be injected through the catheter. The PET scanner is shaped like a doughnut. Participants will lie on a bed that slides in and out of the scanner. Participants will wear a molded a plastic mask that fits the head. Another catheter will be put into an artery at the wrist or elbow area. Vital signs will be monitored during the PET scan. Participants will have a test during the PET scan to monitor heart function. Participants will have blood and urine tests. Participants will have 1 magnetic resonance imaging (MRI) scan. The MRI scanner is a metal cylinder surrounded by a strong magnetic field. Participants will lie on a table that slides in and out of the cylinder.
Background: Movement disorders have many different causes and symptoms. Researchers still do not fully understand which parts of the brain are involved in fine movement. They want to learn about which brain regions could be abnormal in people with movement disorders. Objective: To better understand how the brain controls movement. Eligibility: Healthy, right-handed adults age 18-70 years old. Design: Participants will be screened with a physical exam and questions about their handedness. They may have a urine test. Participants will have 1 or 2 clinic visits. The first visit will last about 1.5 hours. The second will last about 3 hours. Participants will have structural magnetic resonance imaging (MRI). A strong magnetic field and radio waves take pictures of the brain. Participants will lie on a table that slides in and out of a metal cylinder. Participants may have transcranial magnetic stimulation. A wire coil is held on the scalp. A brief electrical current is passed through the coil and creates a magnetic pulse that stimulates the brain. Participants will wear a pair of glasses or a headband with small sensors so researchers can track head position. Participants will perform a simple index finger movement task. Participants may have surface electromyography from at least two hand muscles. Small metal disk or adhesive pad electrodes will be taped to the skin. Participants will be seated in a comfortable chair with their hands placed on a pillow. Participants may have an electroencephalography. A cap with small disc electrodes will be placed on the scalp.
Background: After a stroke, the balance between the two halves of the brain can be lost. This may cause people to lose the ability to perceive a side of space. This is called neglect. Having people wear prism glasses (called PA) can reduce neglect symptoms. Researchers want to find out more about how PA, and whether it restores the balance in the brain. Objective: To learn how prism adaption temporarily changes vision and connections in the brain. Eligibility: People ages 18 75 with brain damage of the right side of the brain from a stroke or other cause, leading to neglect. Healthy volunteers ages 18 75. Design: Participants will have 1 3 visits. Participants will be screened with a neurological exam. They may also have: Tests of thinking and vision Tests to see which eye and hand they prefer A pregnancy test All participants will: Answer questions about their personality, style of thinking, and beliefs. Do simple tasks on paper or computer Have magnetic resonance imaging. They will lie on a table that can slide in and out of a cylinder in a strong magnetic field. Participants will lie still or do computer tasks in the scanner. Participants may also have: Transcranial magnetic stimulation. A brief electrical current passes through a wire coil on the scalp. This creates a magnetic pulse that affects brain activity. Participants may be asked to tense certain muscles or perform simple actions or tasks. PA. They will sit in front of a board and point to a dot on it while they wear prism glasses that shift vision to the left or right.
Background: Some people cannot make medical treatment decisions on their own. The people who make decisions on their behalf are called medical surrogates. Sometimes surrogates cannot predict which treatment course the person or their loved ones would have chosen. The surrogates often become distressed because of making these decisions. Researchers think a tool called a Patient Preference Predictor (PPP) may be able to make the process easier. The PPP would predict what treatment the person would want. This is based on treatment preferences of similar people in a similar circumstance. Researchers want to interview surrogates to explore their views on the PPP. Objective: To explore surrogates views on incorporating a PPP into shared medical decision-making. Eligibility: People 18 years or older who: Have acted as a surrogate medical decision-maker within the past 3 years. This includes decisions about treatment, medication, hospice care, hospital admission, or discharge. Are not pregnant Design: Participants will be screened by meeting with clinicians in person or by phone to discuss the study. Participants will take part in a focus group. This is a small group of people discussing their thoughts and opinions. This will last for about 2 hours. Participants will be served a light meal. Participants will provide information about themselves and their views. They will talk about their past experiences making medical decisions for someone. They will discuss how they felt about these decisions. The PPP will be explained to participants. They will give their views on it. The research team will audio record the focus group and take notes. Participants will fill out questionnaires.
Background: The immune system defends the body against bacteria and other harmful invaders. But it can overact and attack healthy cells by mistake. The group of drugs called glucocorticoids (GCs) can calm down an overactive immune system. But they often cause negative side effects. Researchers want to learn how human genes respond to GCs. Genes live inside each cell of the body. They tell our cells how to function. Researchers hope the results of this study will show them how to develop better drugs that will have the benefits of GCs without the side effects. Objectives: To study how human genes respond to glucocorticoid drugs. Eligibility: Healthy adult volunteers ages 18-64. Design: Participants will be screened with a medical history and physical exam. They will have a heart test and blood tests. The study visit will last about 6 hours. Participants will have medical history, physical exam, and 3 blood draws. Participants will have a skin biopsy. An injection will numb the skin on one arm. Then a tool will remove a piece of skin about as big as a pencil eraser. A GC cream will be applied to the other arm. Participants will get the GC study drug for 30 minutes. It will be a liquid that will drip through a needle placed in an arm vein. Participants will have a skin biopsy of the arm that had the cream applied. Participants will have follow-up calls 1 and 4 days later. They will be asked about reactions or other health problems.