OBJECTIVE:
The purpose of this study is to identify structural brain regions, using a block design blood oxygenation level-dependent functional magnetic resonance imaging (BOLD-fMRI), which are differentially activated based on the sense of self-agency felt by making simple finger movements. We will compare the activations of healthy volunteers with patients diagnosed with a functional movement disorder (FMD) who we hypothesize will have an impaired sense of volition.
STUDY POPULATION:
We intend to use 25 right-hand dominant, adult healthy volunteers for comparison with 50 patients diagnosed with a FMD. We also wish to study an additinal 5 patients witha complete or near-complete sensory neuropathy.
DESIGN:
The sense of self-agency (SA) will be modulated using a visual task-based stimulus asking subjects to manipulate the position of an artificial hand projected onto a display in the magnetic resonance imaging (MRI) scanner. Subjects will use their own right hand to make slow sequential finger movements which will be represented visually with the aid of a Cyberglove. During a behavioral training phase, subjects will practice using the apparatus. The level of control will be randomly changed to one of five states: 100% control, 75%, 50%, 25%, or random/no control. After subjects are comfortable with the apparatus and endorse SA over the displayed hand, they will undergo fMRI scanning. FMD patients who do not wish to participate in the fMRI portion of the study may still participate in the behavioral testing portion.
The imaging phase of the experiment will have five sets of 6 minute scanning sessions where the subject is instructed to slowly open and close sequential fingers of their right hand. The level of control will be changed pseudo-randomly throughout the scan sessions. A control contrast consisting of the subject observing a moving hand will also be integrated into the blocks. An additional control contrast involving the subject moving their hand without visual feedback will also be included. These contrasts will serve in the analysis phase to help eliminate hemodynamic activity related to visual-motor feedback. At the completion of fMRI scanning, a baseline high-resolution MRI T1 scan will be obtained for anatomic localization and co-registration. At the completion of the imaging portion, subjects will also be asked to report the percentage of control they subjectively feel over the displayed hand using a final data set for behavioral testing.
OUTCOME MEASURES:
The primary outcome of this study is the difference in activation of brain structures in response to a loss of SA between FMD patients, sensory neuropathy patients, and healthy controls. In particular, we are interested in the presence of any differential activation in the dorsolateral prefrontal cortex, insula, inferior parietal lobes, pre-supplementary motor association cortex (pre-SMA), and/or the anterior cingulate which may occur as SA is increased or decreased. A secondary analysis will utilize the individual subject perceptions of percent control during the behavioral training phase as the regressors for activation rather than the objective control settings.
