Brain Function in Performance of Motor Tasks
This study will examine how the areas in the brain are connected when they are controlling two finger movements at the same time. It will look at how people use what they see to help guide two different movements. This ability, which is important in everyday life, can be a problem for patients with neurological problems.
Healthy right-handed volunteers 18 years of age and older may be eligible for this study. Candidates are screened with a medical history, physical examination and magnetic resonance imaging (MRI) of the brain. MRI uses a strong magnetic field and radio waves to obtain images of body organs and tissues. The MRI scanner is a metal cylinder surrounded by a strong magnetic field. The subject lies on a table that can slide in and out of the scanner, wearing earplugs to muffle loud noises that occur during the scanning.
Participants undergo functional MRI (fMRI). This is a standard MRI that is done while the subject performs skilled finger tasks in response to instructions they see on a screen. Researchers localize brain areas which show activity changes while the tasks are performed. Before the test session begins, subjects complete a questionnaire and have an opportunity to practice the task.
Subjects control the position of one or two cursors on a screen using one or two fingers. They perform tracking or pointing tasks according to what they see on the screen. During the single-task experiment only one task is presented on the screen. During the dual-task experiment, two tasks are presented on the screen. Subjects perform either the single-task or dual-task experiment, but not both. The fMRI lasts about 90 minutes, with subjects asked to lie still during the scan for up to 9 minutes at a time.
After completing the fMRI, subjects are scheduled for a research electroencephalogram (EEG) and magnetoencephalogram (MEG). The test is done while the subject performs tasks so that researchers can learn about the timing of changes in activity in certain brain regions during performance of the same tasks done for the fMRI.
|Study Design:||Time Perspective: Prospective|
|Official Title:||Brain Connectivity and Sensorimotor Integration During Dual/Single Motor Tasks|
|Study Start Date:||July 2007|
|Estimated Study Completion Date:||November 2011|
Using a block design BOLD-fMRI, we want to investigate the connectivity in brain regions when two motor responses are performed in the same time. The designs will be replicated using EEG and MEG to understand the time course of the activated brain network better. It will allow us to map the brain processes involved in sensorimotor integration and attentional sharing.
160 individuals subdivided in:
- 110 adult healthy volunteers
- 25 patients with Parkinson Disease
- 25 patients with Focal Hand Dystonia
Two experiments will be performed using MEG, EEG and fMRI techniques. Both experiments will use visuo-motor control tasks. Two motor responses (given by two fingers of the dominant hand) will be simultaneously performed. Experiment 1 will use single motor tasks; Experiment 2 will use dual motor tasks. In both experiments, the attention demands will vary with the execution mode of the motor outputs (competitive or cooperative). In competitive tasks, the visual stimuli will be used to perform two independent motor outputs. In cooperative tasks, the visual stimuli will be used to perform two coupled motor outputs. The effect of the execution mode on brain connectivity will be isolated comparing competitive and cooperative tasks. The sensory information must be associated to the motor command to perform a given motor task: this process is called sensorimotor integration. With both experiments, we will be able to dissociate the network connectivity linked to:
- sensorimotor integration demands for focused attention in a single task,
- sensorimotor integration demands for divided attention in a dual motor task.
After subjects have been properly trained to perform the tasks, they will undergo fMRI scanning MEG and EEG recording. Subjects will perform the tasks presented pseudo-randomly during six sets of 5-minute sessions. We will record their muscular activity via EMG surface electrodes.
The primary outcomes are the task-dependent functional connectivity (for fMRI) between areas and coherence (for MEG and EEG) of cerebral sources relative to performance of the tasks. The force control of two fingers in the same time would elicit blood oxygen level dependent (BOLD) signal and electrical brain activity variations in the network involved in manual dexterity. We are interested in studying the connectivity between the homologous motor areas of the two hemispheres, and between prefrontal cortex and parietal cortex, to understand sensorimotor integration processes during competitive and cooperative dual tasks. As a second measure, we are interested in analyzing coherence between MEG-EMG and EEG-EMG signals.
|United States, Maryland|
|National Institutes of Health Clinical Center, 9000 Rockville Pike|
|Bethesda, Maryland, United States, 20892|