View clinical trials related to Normal Physiology.
Filter by:Background: - Two areas on the surface of the brain, the dorsolateral prefrontal cortex (DLPFC) and motor cortex (MC), play a key role during learning. Researchers are interested in determining the effect that transcranial magnetic stimulation (TMS) on the DLPFC and MC has on participants' performance of learning tasks. By studying the effect of TMS on reaction time, learning, and memory, researchers hope to better understand how to treat conditions such as Parkinson's disease and traumatic brain injury that affect these parts of the brain. Objectives: - To study the effects of transcranial magnetic stimulation on the dorsolateral prefrontal cortex and motor cortex. - To learn which areas of the brain are used to perform certain learning and memory tasks. Eligibility: - Healthy, right-handed individuals between 18 and 70 years of age. Design: - Participants will be screened with a physical and neurological examination and a medical and psychiatric history. - Participants will be asked to take part in one of five different parts of this study. Most participants will have four 2-hour visits to the National Institutes of Health Clinical Center. Some participants (those involved in Part 5) will have only one 2-hour visit. - Parts 1 and 2 (four visits): Participants will have TMS, and then do a learning task that may provide a small monetary reward. On the first visit, before the TMS, participants will take an intelligence test based on reading aloud the words given on a card. Participants who have not had a routine magnetic resonance imaging (MRI) scan of the brain within the past year will also have a scan. - Parts 3 and 4 (four visits): Participants will have a functional MRI scan while doing a learning task that may provide a small monetary reward. On the first visit, before the functional MRI, participants will take an intelligence test based on reading aloud the words given on a card. Participants who have not had a routine magnetic resonance imaging (MRI) scan of the brain within the past year will also have a scan. - Part 5 (one visit): Participants will take an intelligence test based on reading aloud the words given on a card. Then, participants will have TMS followed by a functional MRI scan. During the functional MRI, participants will do a button-pressing task that may provide a small monetary reward. - Participants will also be asked to provide a small blood sample for genetic analysis.
Background: - Many treatments for immune system disorders involve the use of stem cells that have been collected from blood marrow. To obtain these stem cells without surgery, individuals receive granulocyte colony-stimulating factor (G-CSF) to encourage the production of stem cells that can be collected through blood donations. However, not all patients or normal donors respond to G-CSF alone. - Plerixafor, recently approved by the Food and Drug Administration, is different from G-CSF but also allows stem cells to be collected from donated blood. However, more research is needed on the quality and viability of the stem cells collected after using both G-CSF and plerixafor. Objectives: - To collect and study the blood cells produced after treatment with G-CSF and plerixafor in healthy volunteers. Eligibility: - Healthy volunteers between 18 and 65 years of age who are eligible to donate blood. Design: - Participants will be screened with a medical history, physical examination, and initial blood tests. - At the start of the study cycle, participants will receive daily morning injections of G-CSF for 5 days. These may be given at the clinical center or by the participant after teaching, depending on the participant s preference. - On the morning of Day 4, participants will visit the clinical center to provide a blood sample after the injection. On the evening of Day 4, participants will receive an injection of plerixafor. - Participants will have the final injection of G-CSF on the morning of Day 5, and will provide another blood sample. - On Day 5, participants will have apheresis to separate the stem cells from the rest of the blood. The apheresis may take up to 5 hours to complete. - The study will end after a follow-up phone call 7 to 14 days after the apheresis procedure.