Rhythm Perception and Generation

Overview

This study will examine how different brain areas are involved in the perception of rhythmic patterns and the performance of rhythmic movements. Patients with certain types of brain diseases, such as Parkinson's disease and some types of stroke, may have difficulty performing rhythmic movements, such as finger tapping. Healthy, right-handed volunteers between 21 and 65 years of age may be eligible for this study. Candidates with visual, motor or hearing problems are excluded, as are musicians and pregnant women. Participants will come to the National Institutes of Health (NIH) Clinical Center for up to six sessions of functional magnetic resonance imaging (fMRI) scanning. MRI uses a strong magnetic field and radio waves to obtain images of body organs and tissues. The scanner is a metal cylinder surrounded by a magnetic field. During the MRI, the subject lies still for up to 20 minutes at a time on a table in the cylinder and wears earplugs to muffle loud knocking noises that occur with the electrical switching of the magnetic fields. He or she can communicate with the MRI staff through a microphone at all times during the procedure. For fMRI, images are obtained while the subject performs a task, such as hearing sounds or moving a finger. The machine detects changes in brain movement that are involved in performing the task. The tasks are explained, and subjects can practice them before entering the scanner.

Objective Rhythmic movements, such as finger tapping, are relatively simple. However, many brain areas including motor, somatosensory, premotor and prefrontal cortex, supplementary motor area, basal ganglia, cerebellum, etc. have been reported to be activated during rhythmic movements. Patients with lesions located in the extrapyramidal or cerebellar system, such as patients with Parkinson's disease, cerebellar ataxia or stroke with a lesion in these systems, have difficulties in performing rhythmic movements. Timing deficits after basal ganglia or cerebellar damage could also be due to abnormalities in interconnecting cortical systems commonly associated with these processes. Few studies have examined involvement of cerebral cortex in time perception. The purpose of this study is to detect the brain areas associated with three hypothesized processes associated with rhythm perception and generation: (1) perception of external rhythmic stimulation, (2) internal rhythm generation and (3) execution of rhythmic movement. To investigate whether the process of rhythm perception is common across sensory modalities, we will use auditory and visual stimulation. Study population This research will be conducted using normal adult volunteers. Design Using functional magnetic resonance imaging, we will examine the brain activity of subjects while they will hear or watch rhythmic stimulation and press buttons rhythmically with their fingers. A series of experiments will be designed to demonstrate the hypothesized three processes separately. Outcome measures The brain activity correlated with experimental conditions and behavioral data (the timing error of button press to the corresponding rhythmic stimulation) will be collected and analyzed by using statistical parametric mapping (SPM). The findings we expect to obtain with this experiment will contribute to basic knowledge for better understanding of the pathophysiology of the disturbance of perception and generation of rhythm in patients with neurological disorders, and give theoretical background for repetitive, rhythmically patterned movement training in neurorehabilitation.