27 Clinical Trials for Various Conditions
This study sought to investigate whether modulation of cortical excitability of the gluteal musculature, via tDCS paired with exercise, will reduce the amount the knee caves in during functional tasks in individuals with PFP. The objective is the explore if having tDCS target the area of the brain controlling hip muscles, when paired with exercise, will be more effective in reducing the amount the knee caves in for individuals with PFP versus those who receive exercise alone as their treatment. The aim is to contribute our findings to the growing knowledge in this area in order to help establish the possibility, and feasibility, of its use in clinical settings to strengthen traditional treatments for this patient population.
This study aims to determine the effects of aerobic exercise as a primer to add-on virtual reality (VR)-based rehabilitation on balance, postural control and neuroplasticity (ability of brain to adapt in structure and function) in individuals with Parkinson's disease (PD). This study will utilize two groups - one group will receive the exercise and VR, while the other group will receive stretching exercise and VR over eight weeks. The study team will administer outcomes at baseline, post-intervention (8 weeks) and follow-up (6 weeks after post-assessment).
To test whether measures of cortical excitability derived from motor cortex transcranial magnetic stimulation (TMS) in patients with traumatic brain injury reflect heightened excitability relative to healthy controls and whether such measures can be used to distinguish patients with post-traumatic epilepsy from patients with head trauma but no epilepsy
This exploratory study will determine if there are differences in cortical excitability between patients suffering from cyclic vomiting syndrome (CVS) and healthy control subjects, as assessed by a non-invasive method of brain stimulation (Transcranial Magnetic Stimulation, TMS).
The investigators plan to use a pre-test post-test research design to investigate whether dry needling (DN) has an effect on cortical excitability in patients with chronic low back pain (CLBP), specifically in patients who have developed central sensitization (CS). Therefore, the primary purpose of this study is to examine the immediate effects of a single session of DN on cortical excitability and neurosensory responses in patients CLBP. There are two specific aims: 1) to examine whether a single session of DN will change cortical excitability corresponding to the lumbar multifidus (LM) muscle, and 2) to examine whether a single session of DN will change neurosensory responses to the stimuli applied to the LM muscles. The investigators also are interested in exploring whether DN has a differential effect on cortical excitability in patients with CLBP who have developed CS vs. those who have not developed CS. Therefore, the secondary purpose of the study is to compare the immediate effects of a single session of DN on cortical excitability between patients with CLBP who have developed central sensitization (CS) and those who do not have CS. The specific aim is to compare cortical excitability corresponding to the LM in participants with and without CS after a single session of DN.
Dravet syndrome (DS) is an epileptic encephalopathy caused by pathogenic variants in the SCN1A gene resulting in medically refractory epilepsy and psychomotor delays. As a pilot study assessing for feasibility, the investigators aim to test whether alterations in cortical excitatory:inhibitory ratio can be reliably recorded. The investigators will utilize transcranial magnetic stimulation (TMS) metrics of cortical excitatory and inhibitory tone as an initial step towards translating findings from rodent genetic models of DS into disease-specific biomarkers and offer future measures of therapeutic target engagement in this patient population. Participants will complete two visits, each consisting of a TMS session and an EEG session. Visits will be scheduled 4-8 weeks apart.
The objective of the current proposal is to identify 1) how aging-related changes in GABAergic cortical inhibition affect motor performance, and 2) how aerobic exercise may improve inhibitory function and facilitate motor learning.
The overarching purpose of this study is to develop a technique that is capable of identifying neurophysiological biomarkers sensitive enough to detect preclinical dementia by integrating Transcranial Magnetic Stimulation (TMS) and Functional Magnetic Resonance Imaging (fMRI). More specifically, this project has two specific aims: * 1. To characterize cortical excitability and its relation to cognitive function using single-pulse TMS paradigm in Mild Cognitive Impairment (MCI) and healthy older adults. * 2. To delineate cortical plasticity and its association to cognitive function using repetitive TMS paradigm and resting-state fMRI in MCI and healthy older adults. Techniques to artificially and precisely stimulate brain tissue are increasingly recognized as valuable tools both in clinical practice and in cognitive neuroscience studies among healthy individuals. Transcranial magnetic stimulation (TMS) is a non-invasive approach to stimulate the brain. Importantly, unlike other invasive brain stimulation techniques (e.g., surgical deep brain stimulation), no surgery, anesthesia, or sedation is involved. Instead, TMS involves placing a magnetic coil on the surface of the head. This coil then generates a magnetic field that is about the same strength as the magnetic field used by MRI machines, and when this magnetic field rapidly alternates, the neurons under the coil are excited. Extensive guidelines have been published by experts in the field to ensure safe use, and the thousands of patients \& research participants who have received TMS in compliance with these guidelines demonstrate the safety of this practice. Depending on the method of use, TMS is very versatile -- it can be used to study research questions pertaining to the neural circuitry of the brain, it can be used as a diagnostic device, and it can be used therapeutically to treat various neurological conditions. In this study, the investigators intend to further study the potential for diagnostic applications of TMS. More specifically, TMS and brain imaging techniques will be used in combination in order to more sensitively diagnose dementia - perhaps even before symptoms emerge. Right now, there is no reliable method for doing so and it is difficult to distinguish between the forgetfulness of healthy aging and the early signs of disease. Our approach may provide a more sensitive diagnostic tool, which is likely to improve clinical outcomes.
The purpose of this study is to learn if measures of brain activity are different in children and adolescents with depression who are in different stages of treatment. This is important because it may identify a biological marker for depression that could one day be used to identify depressed children who would benefit from certain treatments (medications for example), or to monitor how well treatments are working. Brain activity measures(known as cortical excitability and inhibition) will be collected by Transcranial Magnetic Stimulation (TMS). TMS is a noninvasive (no surgery or implants) brain stimulation technology which can make parts of the brain work without putting any wires or chemicals into the body. Measurements will take place over one 3-hour visit. This study does not provide any form of treatment. \*There is an optional portion of the study that uses a brain scan to gather measures of brain structure and brain chemicals. The brain scan is called magnetic resonance and spectroscopy (MRI/MRS). MRI/MRS uses magnetic fields to study the structure of the brain and brain chemicals. The PI will determine eligibility for the MRI/MRS portion of the study.
Specific Primary Aims include: Aim # 1. The investigators explore the feasibility of using the TMS to investigate the cortical excitability and to inhibit meth cue craving in meth dependent population. The investigators anticipate that meth elevates cortical excitability measured by motor threshold, causes changes of cortical silent period, and RC. The investigators also anticipate that paired pulse measures (short-interval intracortical inhibition, short-interval intracortical facilitation and long-interval intracortical inhibition) will be different from healthy control, which are more directly linked to glutamatergic cortical facilitation and GABAergic inhibition, respectively. Aim # 2. Given the change of the cortical excitability in meth users, the investigators will use inhibiting TMS (1 Hz) over medial prefrontal cortex to study whether TMS can be used to reduce cue craving. The investigators hypothesize that repetitive TMS reduce meth cue craving in meth dependent population compared with sham rTMS.
The purpose of this study is to find out if children with attention-deficit, hyperactivity disorder (ADHD) have a difference in how their brain cells "fire" or react. The investigators also want to find if brain cell "firing" can tell us how severe of symptoms a child has from ADHD. Finally, the investigators want to see if giving an ADHD medication called atomoxetine can make the ADHD symptoms in a child better and if the improvement shows a change in brain "firing".
This study will use transcranial magnetic stimulation (TMS) to study the function of the cerebral cortex (outer layer of the brain) in people with obsessive compulsive disorder (OCD) and related disorders. A non-invasive procedure, TMS activates areas of the brain with magnetic pulses that travel through the scalp and head and cause small electrical currents in the brain. People 18 years of age and older with OCD and disorders that may be related-tic disorders, such as Tourette's syndrome, focal dystonia (localized muscle cramps), body dysmorphic disorder (hypersensitivity to changes in appearance), eating disorders, such as anorexia nervosa, trichotillomania (compulsive hair-pulling)-may be eligible for this study. Healthy normal volunteers will also be enrolled. Candidates will be screened by telephone interview. Participants will undergo TMS. For this procedure, an insulated wire coil is placed on the subject's head. A brief electrical current passes through the coil, creating a magnetic pulse that travels through the scalp and skull and causes small electrical currents in the outer part of the brain. The stimulation may cause muscle, hand or arm twitching, or may affect movement or reflexes. During the stimulation, the subject may be asked to tense certain muscles slightly or perform other simple actions. The electrical activity of muscles during stimulation is recorded with a computer or other recording device, using electrodes attached to the skin with tape. Subjects will receive fewer than 500 magnetic pulses, and the study will take less than 3 hours. Participants may repeat the procedure on several occasions, if they agree.
Major depressive disorder (MDD) is a serious mental illness and the leading cause of disability worldwide. New pharmacotherapeutic agents with complementary neurobiological mechanism and better side effect profile are of great needs. In addition to the monoamine system, the glutamatergic system plays a crucial role in MDD. L-theanine (N5-ethyl-L-glutamine) is the primary psychoactive component uniquely in green tea. Preclinical studies have demonstrated anti-depressant effect of L-theanine in rodents and provided evidences for its pharmacological properties of N-methyl-D-aspartate (NMDA) and gamma-aminobutyric acid (GABA) agonism. Yet these effects have not been proven in humans. Only one open-label clinical trial has studied and supported antidepressant effects of L-theanine in MDD patients. We propose using pair-pulse transcranial magnetic stimulation (ppTMS) to probe how L-theanine may manipulate the glutamatergic and GABA systems in the frontal region by changing cortical excitability first in healthy subjects. We plan to investigate the neurobiological effects of L-theanine in healthy subjects first. Granted that the first phase pilot trial provides neurophysiological evidence of L-theanine on motor cortex excitability in human subjects, next phases of studies on L-theanine in MDD patients cortical excitability could be justified.
The AMPLIFI study (Adaptive Modulation of Plasticity through Lactate and Fitness Interventions) investigates how short-term aerobic exercise influences brain plasticity and learning in older adults and stroke survivors. The study compares three groups: one performing aerobic cycling exercise at an intensity that increases lactate levels, one doing low-intensity exercise, and one receiving health education without exercise. All participants will complete motor learning tasks and undergo brain stimulation testing (using transcranial magnetic stimulation, or TMS) to assess how well the brain responds to training. The goal is to understand whether different types of exercise can improve brain function, movement, and memory, and how the body's response to exercise (like lactate levels) might support brain health. This research may help identify low-cost, non-invasive interventions-such as targeted exercise-that improve motor and cognitive outcomes in aging and stroke recovery.
Stroke is a leading cause of disability with many patients suffering chronic motor function impairments that affect their day-to-day activities. The goal of this proposal is to provide a first assessment of the efficacy of an innovative non-invasive brain stimulation system, kTMP, in the treatment of motor impairment following stroke.
The goal of the proposed research is to determine the influence of transcranial direct current stimulation (tDCS) on long-term motor learning, transfer of motor learning, and cortical function in Parkinson's disease (PD). The project comprises a 2 week training study that will involve tDCS applied during two practice motor tasks with behavioral, clinical, and physiological evaluations at baseline as well as 1, 14 and 28 days following the 2 week training and stimulation period. The findings of the proposed studies should have significant clinical significance and applications to comprehensive intervention therapy development in the treatment of PD.
The purpose of this study is to examine if thigh muscle weakness and the lack of muscle activation that accompanies ACL injury can be improved through a form of mental coaching and encouragement, known as operant conditioning.
Stroke is the third most common cause of death in the United States after heart disease and cancer, and the leading cause of long-term disability. This work will develop an innovative brain stimulation method (paired associative stimulation) which might set the stage for a new treatment for stroke rehabilitation.
The purpose of this study is to learn if measures of brain chemicals from a brain scan called Magnetic Resonance Imaging and Spectroscopy (MRI/MRS) and brain activity (known as cortical excitability and inhibition) collected by Transcranial Magnetic Stimulation (TMS) are different in adolescents with depression who are in different stages of treatment. Researchers are conducting this study to learn more about how the brain works in adolescents with depression and without depression (healthy controls). This is important because it may identify a biological marker (a measure of how bad an illness is) for depression that could one day be used to identify depressed adolescents who would benefit from certain treatments (medications for example) or to monitor how well treatments are working.
Drug therapy of atypical parkinsonism is generally considered either ineffective or minimal 1. Therefore, there is an urgent need to find alternative therapies to treat atypical parkinsonian disorders. Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive tool that modulates cortical excitability with minimal discomfort and holds therapeutic promise in treating neurological and psychiatric disorders. The basal ganglia-thalamocortical circuits that are affected in Progressive Supranuclear Palsy (PSP) and Corticocbasal Ganglionic Degeneration (CBGD) are likely structurally and functionally segregated. The 'motor' circuit is implicated in parkinsonian akinesia and hypokinesia; a 'prefrontal' circuit is implicated in working memory and mood regulation, and linked with non-motor symptoms such as depression and apathy. In this proposal, we characterize motor and prefrontal network dysfunction in PSP and CBGD patients, and propose that high-frequency and low-frequency rTMS directed over separate motor and prefrontal cortical targets of each network may show specific and selective beneficial effects on motor vs. cognitive function in PSP and CBGD patients, respectively. Quantitative motor outcome measures include timed finger tapping tasks. Quantitative cognitive outcome measures comprise a visual analogue scale (VAS). If successful, this pilot study will provide proof of principle data to suggest potential benefits for rTMS in PSP/CBGD patients, and provide sufficient data and experience to support future PSP/CBGD studies that include the use of rTMS to investigate the pathophysiology of motor and non-motor features of PSP and CBGD patients.
OBJECTIVES: About 15% of patients suffering from focal epilepsy are refractory to available pharmacological treatments. Until now, the only hope for such patients has been the development of new pharmaceutical treatments or epilepsy surgery. In case of inoperability, different types of invasive brain stimulation such as vagus nerve stimulation or deep brain stimulation or non-invasive repetitive TMS have been evaluated to determine their anticonvulsive potential. For rTMS, weak and short lasting seizure reduction has been reported in different epilepsy syndromes. A new, non-invasive stimulation technique, transcranial direct current stimulation (tDCS), was useful to modulate cortical excitability in many cortical areas (M1, visual cortex, frontal cortex). Cathodal tDCS, with a current of 1 mA, induced long-term depression in animal models and reportedly decreased the excitability of both human and animal cerebral cortex. In epilepsy patients suffering from a malformation of cortical development, a single session of cathodal tDCS helped reduce seizures briefly. The purpose of this protocol is to study the effects of repeated applications of tDCS on the excitability of the seizure focus in patients with poorly controlled pharmacologically refractory temporal lobe epilepsy. STUDY POPULATION: We plan to study 56 patients between the ages of 18 and 80 suffering from temporal lobe epilepsy. DESIGN: Subjects will be allocated by blocked randomization to one of two groups (parallel design). Group A will receive cathodal tDCS and group B will receive Sham-tDCS on five consecutive days. Each subject will participate in 9 sessions (1 baseline visit, 5 intervention visits, 3 follow-up visits). The effect of the intervention relative to the sham stimulation will be evaluated by comparing seizure frequency and neuropsychological tests during the 8 weeks before and after the intervention. OUTCOME MEASURES: Primary outcome measure will be the mean seizure frequency per 4 weeks in the tDCS group as compared to the Sham-tDCS group. To analyze the effect of the intervention (tDCS), seizures will be evaluated during a 2x4 week baseline period before tDCS and 2x4 weeks after the intervention. Using these data we will calculate the percentage change of seizures per 4 weeks. Secondary outcome measures will be the scores of the neuropsychological testing (HVLT-R, BVMT-R, CTMT, COWAT) and number of epileptiform discharges in the EEG. Furthermore, th...
This study will measure brain excitability in patients with succinic semialdehyde dehydrogenase (SSADH) deficiency, and in their parents. SSADH is a rare inherited disease in which changes in certain brain chemicals affect brain cell activity. Symptoms vary greatly among patients, and may include mental retardation, impaired ability to coordinate movements, and delays in language and speech development. Other symptoms may include poor muscle tone, uncontrolled seizures and other neurological or behavioral abnormalities. Test findings in patients and their parents will be compared with those of healthy normal volunteers. The following individuals may be eligible for this study: patients with SSADH who are between 5 and 24 years of age; parents of patients who are between 18 and 55 years of age; healthy normal children who are between 10 and 17 years of age; and healthy normal adults who are between 18 and 55 years of age. Candidates are screened with blood and urine tests. All participants undergo the following: * Transcranial magnetic stimulation (TMS): This procedure maps brain function. A wire coil is held on the scalp, and a brief electrical current is passed through the coil, creating a magnetic pulse that stimulates the brain. During the stimulation, the subject may be asked to tense certain muscles slightly or perform other simple actions to help position the coil properly. The stimulation may cause a twitch in muscles of the face, arm, or leg, and the subject may hear a click and feel a pulling sensation on the skin under the coil. During the test, electrical activity of muscles is recorded with a computer or other recording device, using electrodes attached to the skin with tape. * Magnetic resonance imaging (MRI): This test combines a powerful magnet with an advanced computer system and radio waves to produce accurate, detailed pictures of organs and tissues. During the scan, the subject lies on a table in a narrow cylinder containing a magnetic field, wearing ear plugs to muffle loud noises that occur with electrical switching of the magnetic fields. He or she can speak with a staff member via an intercom system at all times during the procedure. In addition to standard MRI, subjects may have newer MRI tests, such as diffusion tensor MRI and magnetic resonance spectroscopy. In addition to the above, patients and their parents may also undergo the following tests: * Electroencephalography (EEG): This test records brain waves (electrical activity of the brain). Electrodes are placed on the scalp and brain electrical activity is recorded while the subject lies quietly, breathes deeply, watches flashes of light, or sleeps. Some patients may also have video-EEG monitoring, which involves simultaneous clinical recording using a video camera along with brain wave recording. * Sleep study and multiple sleep latency onset testing (MSLT): Electrodes are placed on the subject's scalp and remain there while the subject sleeps in the hospital overnight. MSLT is done the next day, starting 2 hours after the subject wakes up from the night's sleep. A total of five 20- to 30-minute naps are recorded, each every 2 hours, to access daytime sleepiness. * Nerve conduction studies: This test measures the speed with which nerves conduct electrical impulses and the strength of the connection between the nerve and the muscle. A probe is placed on the skin to deliver a small electrical stimulus, and wires taped on the skin record the impulses.
This study will compare the effectiveness of unilateral versus bilateral exercise training for recovering movement abilities in chronic stroke patients. After a stroke, some people have improved their movement ability by exercising the arm affected by the stroke. Others have improved by exercising both arms together. This study will compare these two kinds of exercise to see which might work best. Healthy volunteers and people who have had a stroke more than 6 months ago may be eligible for this study. Stroke patients must have some weakness in their stroke-affected arm. All participants must be 18 years of age or older. Candidates are screened with a clinical and neurological examination. Women who can become pregnant have a pregnancy test. Stroke patients have a magnetic resonance imaging (MRI) study of the brain if they have not had one in the last year. Participants undergo the following tests and procedures: MRI: This procedure uses a magnetic field and radio waves to produce images of body tissues and organs. The subject lies on a table that slides into the scanner (a narrow cylinder), wearing earplugs to muffle loud knocking sounds that occur during the scanning process. The procedure lasts about 45 minutes, during which time the subject must lie still for up to 30 minutes. Testing sessions: There are six test sessions - two to familiarize the subject with the reaching test, two to do the reaching test plus transcranial magnetic stimulation (TMS) before and after an exercise session, and two to do the reaching test plus TMS one day after the exercise session. The sessions are on consecutive days, with a 1-week break after session 3. The procedures involved are: * Reaching test: The subject responds as quickly as possible to a "GO" signal presented on a computer monitor by performing a reaching movement with his or her arm. The activity from the arm muscles is recorded using surface electrodes. During this test, a questionnaire is used to determine the subject's attention, fatigue, and mood. * TMS: For this test, a wire coil is held on the scalp, and a brief electrical current is passed through the coil, creating a magnetic pulse that stimulates the brain. During the stimulation, the subject may be asked to tense certain muscles slightly or perform other simple actions. The stimulation may cause a twitch in muscles of the face, arm, or leg, and the subject may hear a click and feel a pulling sensation on the skin under the coil. The effect of TMS on the muscles is detected with small metal disk electrodes taped onto the skin of the arms. The subject performs the reaching test while TMS is delivered at various times after getting the "GO" signal. * Arm exercises: The subject is seated in front of an exercise device that has two handles that slide forward and backward along a set of tracks. The subject is asked to slide either one or both handles back and forth repeatedly, alternating 5 minutes of arm exercise with 5 minutes of rest for 30 minutes.
This study will examine whether blind people develop changes in the brain that improve memory function. Previous studies have shown that blind people, on average, perform better in memory tasks than sighted people. A possible reason for this is that parts of the brain that process visual information in sighted individuals are engaged in processing mnemonic (remembering) information in blind people. Blind and sighted people 18 years of age and older are eligible for this study. Healthy, sighted individuals may participate in Part 1 of the study, which is designed to find appropriate words to use in tests for Part 2 of the study. Part 2 will include sighted people and blind people. It will examine whether the (visual) brain in blind people is processing mnemonic information in a way that helps with day-to-day memory functions. Blind participants in this study must have lost their sight by age 4. Candidates will be screened with a medical interview and examination and a brief test of short-term and long-term verbal memory. Sighted patients will also be tested for visual memory and for handedness. Part 1 - Word Recognition Testing (2 sessions) * Session 1: Participants listen to a number of words over a loudspeaker and try to remember them for a memory test that will be given 30 minutes later. For the test, subjects listen to words again and press one of three buttons as quickly as possible after hearing the word. The buttons signal whether the subject does or does not recognize the word with a 1) high level of confidence or 2) low level of confidence. * Session 2: Participants hear a noun over a loudspeaker and have to find an appropriate verb for it, such as the verb (read) for the noun (book). Part 2 - MRI Scanning and TMS Experiments (5 - 7 sessions) * Magnetic resonance imaging (MRI): Participants perform the same procedures as described above for Part 1 while undergoing MRI of the brain. For this test, the subject lies on a table inside the MRI scanner - a narrow cylindrical tube with a strong magnetic field. Scanning time varies from 20 minutes to 3 hours, with most scans lasting between 45 and 90 minutes. (Earphones are used to hear the words for this test instead of a loudspeaker.) * Transcranial magnetic stimulation (TMS): Participants undergo TMS while performing the same procedures described for Part 1. For TMS, a wire coil is held over the scalp. A brief electrical current is passed through the coil, creating a magnetic pulse that stimulates the brain. Subjects may hear a click and feel a pulling sensation on the skin under the coil. There may be a twitch in muscles of the arm or leg. During the TMS, electrical muscle activity is recorded through the electrodes with a computer or other recording device. Each session lasts a maximum of 3 hours.
This study will evaluate the usefulness of transcranial magnetic stimulation (TMS) in measuring cortical excitability. The cortex is the outer part of the brain. Patients with seizures have increased cortical excitability and are often treated with antiepileptic drugs to reduce this excitability. The therapeutic effects of antiepileptic drugs are usually tracked with blood tests that measure their blood levels. However, these blood tests may not always correctly reflect the effects of the drugs on the brain. TMS has been used successfully to measure cortical excitability in many neurological diseases, including epilepsy, and may be helpful in measuring drug effects on the brain directly. For this procedure, a wire coil is held over the scalp. A brief electrical current is passed through the coil, creating a magnetic pulse that stimulates the brain. This may cause a pulling sensation on the skin under the coil and twitching in muscles of the face, arm, or leg. During the stimulation, the participant may be asked to tense certain muscles slightly or perform other simple actions. Healthy normal volunteers between 18 and 55 years of age may be eligible for this study. Candidates will be screened with a medical history, physical and neurological examination, electroencephalogram (EEG), and blood tests. On the first day of the study, participants will have a baseline TMS and will be randomly assigned to take one of two antiepileptic drugs: group A will take the carbamazepine; group B will take lamotrigine. If they wish, participants may be admitted to the NIH Clinical Center for the first 5 days of drug administration while the proper dosage is being determined. They will then be discharged and continue taking the drug for a total of 36 days. During this time, they will have daily blood tests and TMS from days 2 through 5, and again on days 12 and 36. Group A will have additional blood sampling and TMS on days 37, 39, 44, and 53; Group B will have blood tests and TMS on days 38, 40, 45, and 53.
This two-part study will use transcranial magnetic stimulation, or TMS (see below), to explore how the brain forms memories. People remember only some of the events they experience every day, such as faces they perceive, words they read, speech they hear and interpret, and so forth. The events remembered are those that have been saved or formed in the brain. Part 1 of this study involves testing materials for Part 2, the TMS experiment. Part 2 uses TMS to examine what parts of the brain are involved in forming memories. Information gained from this study may be used in developing methods of enhancing memory in both healthy people and in patients with memory impairments. Healthy right-handed volunteers between 18 and 35 years of age may be eligible for this study. Candidates may be screened with a medical interview and physical examination and a brief test of short- and long-term visual and verbal memory. Eligible volunteers may participate in Part 1 or Part 2 of the study, as follows: Part 1 - Preparation of Words and Picture Materials Participants look at several words or shapes that appear in random order on a computer screen and try to remember them as well as possible for a memory test that will be given 20 minutes later. Each image appears on the screen for 3/4 of a second, with 1-1/4-second intervals between them. For the test, words and shapes are again shown on the computer screen at the same timing and intervals. When the items appear, the subject presses one of three buttons as quickly as possible, determining if he or she has recognized the items with a high or low level of confidence. The entire procedure lasts up to 1 hour, with breaks in between. The purpose of this experiment is to find appropriate words and pictures to use as stimuli in the TMS study described below. Part 2 - TMS Experiment For TMS, the subject sits in a comfortable chair. An insulated wire coil is placed on the scalp, and brief electrical currents are passed through the coil, creating magnetic pulses that stimulate the brain. The pulses may cause a pulling sensation on the skin under the coil and twitching in muscles of the arm or leg. Electrodes are taped to the skin over some muscles of the hands to record the electrical activity of the muscles. Pulses are delivered in trains or short bursts of impulses, each lasting half a second. Participants receive 90 trains for a total of 900 pulses. TMS is applied during the first part of the memory study, when the words and shapes are first presented on the computer screen, but not during the second presentation for memory testing. The entire procedure takes up to 2 hours, with breaks in between. Before the TMS session, participants undergo magnetic resonance imaging (MRI) to determine where to place the coil for TMS. For MRI, the subject lies still for up to 30 minutes at a time on a table that slides into the scanner, a narrow metal cylinder surrounded by a strong magnetic field. Earplugs are worn to muffle loud knocking sounds that occur while the scanner takes pictures. Subjects can communicate with the MRI staff at all times and can ask to stop the procedure at any time.
This study will investigate the effects of the drug flumazenil on brain excitability and the drug's relationship to a natural brain chemical called GABA. Flumazenil is commonly used in hospitals to reverse the effects of a group of drugs called benzodiazepines, one of which is Valium. Benzodiazepines act by enhancing the effects of GABA. Healthy volunteers 21 years of age and older may be eligible for this study. Candidates will be screened with a medical history and physical and neurological examinations. Participants will have transcranial magnetic stimulation (TMS) four times on two different days, before and after receiving an intravenous (through a vein) infusion of either flumazenil or placebo (an inactive sugar solution), as follows: TMS study 1 Drug or placebo infusion TMS study 2 - 15 minutes after infusion TMS study 3 - 60 minutes after infusion TMS study 4 - 120 minutes after infusion In transcranial magnetic stimulation, a very brief electrical current is passed through an insulated coil wire placed on the scalp. These currents stimulate the cortex (outer part of the brain). They may cause muscle, hand, or arm twitching if the coil is near the part of the brain that controls movement, or they may affect other reflexes or movements. During the study, subjects may be asked to make movements, do simple tasks or tense muscles. To record the electrical activity of muscles, electrodes will be taped to the skin over the muscles tested. In some cases, the studies will be videotaped. Flumazenil will be infused through a catheter (thin plastic tube) attached to a needle placed in an arm vein. On one day, subjects will receive a 1-mg injection of flumazenil followed by a continuous infusion of 0.5 mg of the drug for about 30 minutes. On the other day, they will receive placebo, administered in the same manner.