3 Clinical Trials for Various Conditions
This study will explore how the areas in the brain are connected to link what people see to what they do; that is, how they use what they see to help guide their movements. The study uses functional magnetic resonance imaging (fMRI) to look at different areas in the brain while a person performs tasks in which both what they see (visual input) and what they do (their motor response) are related or unrelated. Healthy, right-handed normal volunteers who are 18 years of age or older may be eligible for this study. Candidates are screened with a medical history, neurological examination and MRI scan, if one has not been done within a year of entering the study. MRI uses a magnetic field and radio waves to produce images of body tissues and organs. The subject lies on a table that can slide in and out of the scanner (a narrow cylinder), wearing earplugs to muffle loud knocking sounds that occur during scanning. The procedure lasts about 90 minutes, during which the subject is asked to lie still for up to 30 minutes at a time. Participants undergo fMRI for this 1-day study. fMRI differs from ordinary MRI in that the subject performs tasks during the scanning, allowing researchers to see brain changes that occur during performance of the activity. Before the scan, the subject is trained for the tasks, which include looking at shapes while following them with the fingers and looking at shapes without making finger movements. Following the testing, subjects have a second ordinary MRI scan.
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 is a randomized, pilot interventional study in participants with visual field deficit (VFD) caused by cortical lesion. Damage to the primary visual cortex (V1) causes a contra-lesional, homonymous loss of conscious vision termed hemianopsia, the loss of one half of the visual field. The goal of this project is to elaborate and refine a rehabilitation protocol for VFD participants. It is hypothesized that visual restoration training using moving stimuli coupled with noninvasive current stimulation on the visual cortex will promote and speed up recovery of visual abilities within the blind field in VFD participants. Moreover, it is expected that visual recovery positively correlates with reduction of the blind field, as measured with traditional visual perimetry: the Humphrey visual field test or an eye-tracker based visual perimetry implemented in a virtual reality (VR) headset. Finally, although results will vary among participants depending on the extent and severity of the cortical lesion, it is expected that a bigger increase in neural response to moving stimuli in the blind visual field in cortical motion area, for those participants who will show the largest behavioral improvement after training. The overarching goals for the study are as follows: Group 1a will test the basic effects of transcranial random noise stimulation (tRNS) coupled with visual training in stroke cohorts, including (i) both chronic/subacute ischemic and chronic hemorrhagic VFD stroke participants, and (ii) longitudinal testing up to 6 months post-treatment. Group 1b will test the effects of transcranial tRNS coupled with visual training on a Virtual Reality (VR) device in stroke cohorts, including both chronic/subacute ischemic and chronic hemorrhagic VFD stroke participants. Group 2 will examine the effects of tRNS alone, without visual training, also including chronic and subacute VFD stroke participants and longitudinal testing.