Imaging Study of Automatic Movements

Overview

This study uses magnetic resonance imaging (MRI) to explore the brain activities involved in performing learned automatic movements. Automatic movements are performed without concentrating on the details of the movement. Healthy adult volunteers are eligible for this study. Candidates will have a medical history and brief physical examination and will fill out a questionnaire. Women of childbearing potential will have a urine pregnancy test. Pregnant women will not be enrolled. Participants will perform certain tasks involving movement of the right or left hand while undergoing MRI scanning. They will undergo scanning twice-before and after practicing the movement tasks. Before the second scan, participants will practice the following tasks for 1 week: * Tapping task - subjects use their left index finger to tap a button at a certain frequency. * Sequential movement task - subjects perform sequential finger-tapping movements with their right hand, in which they tap buttons with their fingers at a certain frequency in a 25-second period. There are two sequences of different lengths, referred to as sequence-4 and sequence-12, based on the number of movements in each unit of the sequence. * Visual distraction task - 14-letter sequences consisting of the letters A, G, L, and O will be presented and subjects will be asked to identify the number of times they see a target letter. * Dual tasks - after completing all the above tasks, subjects perform the following dual tasks: Tapping and visual task Sequence-4 finger tap and visual task Sequence-12 finger tap and visual task Tapping and sequence-4 finger tap Tapping and sequence-12 finger tap When the participants can perform the dual tasks correctly 90 percent of the time, the movements will be considered automatic, and the subjects will undergo MRI scanning. MRI uses a magnetic field and radio waves to produce images of the brain. For the procedure, the subject lies still on a stretcher that is moved into the scanner (a narrow cylinder containing the magnet). Earplugs are worn to muffle loud noises caused by electrical switching of radio frequency circuits used in the scanning process. The scan will last about 1.5 hours.

A general characteristic of the motor system is that people can perform some learned movements automatically. The underlying neural correlates of automatic movement have been investigated, but are not fully understood. In the present study, in order to investigate the brain activities contributing to the phenomenon, we use a specially designed dual task paradigm and functional magnetic resonance imaging (fMRI) technique. Forty healthy adult subjects are asked to perform motor tasks (squeezing of hand or sequential movement of fingers) while listening to an auditory distraction task, or to execute two different motor tasks simultaneously. fMRI is obtained during their performance of these tasks. By analyzing fMRI results, we will explore the brain regions especially devoted to the automatic movements.