View clinical trials related to Normal Physiology.
Filter by:Background: Noninvasive brain stimulation (NIBS) may help diagnose and treat psychiatric and neurological illness. But there is not enough research on how to apply NIBS. This includes how strong to make it, where on the brain to apply it, and for how long. Researchers also want to see what the brain is doing when it receives NIBS. Objective: To increase the effectiveness of NIBS. Eligibility: Healthy native English speakers ages 18-65 Design: Participants will be screened under another protocol with: Medical and psychiatric history Psychiatric evaluation Physical exam Urine tests All participants will start with a 2-hour visit for screening. (see below). They may learn how to do tasks that will be used later. After the screening session, they will be scheduled for an MRI session. The next part of the study is 4 substudies. Each substudy includes up to 4 sessions. A session is usually 2-3 hours but can last up to 8 hours. Participants can join multiple substudies, but only 1 at a time. They can do only 1 session on a given day. Each substudy includes the following: Behavioral tests: Interviews; questionnaires; simple tasks; and tests of memory, attention, and thinking Electromyography: Small sticky electrodes on the skin measure muscle activity. Transcranial magnetic stimulation: A wire coil is held to the scalp. A brief electrical current passes through the coil and affects brain activity. Magnetic resonance imaging (MRI): Participants lie on a table that slides into a machine that takes pictures of the brain. A coil is placed over the head. They will perform simple tasks while in the scanner. They may also get TMS. Electroencephalography: Small electrodes on the scalp record brain waves. Sponsoring Institution: National Institute of M
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.
Background: People can feel different levels of pain. This may depend on social, cultural, and biological factors. These factors can also influence how people respond to each other, and how they judge other people s experiences. Researchers want to learn more about these relationships. Objective: To study if social and cultural factors lead to differences in pain experience and how pain is interpreted by other individuals. Eligibility: Healthy adults ages 18-60 Design: Participants will have 1 or 2 visits. Participants will be screened with a medical history and nursing assessment. Participants may have the following: Electric shock through small sticky pads on the arm, leg, or foot. Thermal stimulation. A device called a thermode will be placed on the arm, leg, or foot. A computer controls the thermode temperature. Lowering their hand into very cold water. Videos or pictures of the face will recorded while participants get painful stimulation. A test to record heart electrical activity. Small metal disc or sticky pad electrodes will be placed on the chest. Pulse rate and breathing measured. Sweating will be measured with two small sensors stuck on the hand. A test to measure the electrical activity of facial muscles. Small metal disk or sticky pad electrodes will be attached to the skin. Viewing pictures and/or videos of other people who get painful and nonpainful stimulation. Participants will make decisions about the images. They will respond by keyboard, mouse, or button. Eye tracking. A camera will measure participants pupil size and follow their eye movements. ...
Background: The chemical messenger dopamine carries signals between brain cells. It may affect addiction. Heavy use of pain medicines called opioids may decrease the amount of dopamine available to the brain. Researchers want to study if decreased dopamine decreases self-control and increases impulsiveness. Objective: To learn more about how opiate use disorder affects dopamine in the brain. Eligibility: Adults 18-80 years old who are moderate or severe opiate users Healthy volunteers the same age Design: Participants will first be screened under another protocol. They will: - Have a physical exam - Answer questions about their medical, psychiatric, and alcohol and drug use history - Take an MRI screening questionnaire - Give blood and urine samples - Have their breath tested for alcohol Participants will have up to 3 study visits. They will have 2-3 positron emission tomography (PET) scans. A radioactive chemical will be injected for the scans. Participants will lie on a bed that slides in and out of the donut-shaped scanner. A cap or plastic mask may be placed on the head. Vital signs will be taken before and after the PET scans. Participants will get capsules of placebo or the study drug. They will rate how they feel before, during and after. Participants will have their breath and urine tested each day. Participants will have magnetic resonance imaging (MRI) scans. They will lie on a table that slides into a cylinder in a strong magnetic field. They may do tasks on a computer screen while inside the scanner. Participants will have tests of memory, attention, and thinking. Participants will wear an activity monitor for one week....
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.
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. 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. Over the next 3 months, participants may have up to 4 other study visits. These last 2 to 4 hours each. They include repeats of some of the tests in the required visit. Participants may be recorded at the visits.
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.
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.
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.
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.