Physiology of Volition Studied With Nerve Block
| Status: | Archived |
|---|---|
| Conditions: | Healthy Studies |
| Therapuetic Areas: | Other |
| Healthy: | No |
| Age Range: | Any |
| Updated: | 7/1/2011 |
| Start Date: | June 2010 |
Background:
- The experience of volition that accompanies voluntary movement can be divided into the
sense of will, or deciding to move, and the sense of agency, or feeling that the movement
just made was self-generated. Very little is known regarding the neurological origin of this
sense of volition. Previous research has shown that a particular part of the brain, the
parietal lobe, is involved in our inner sense that we control the movements we make.
Researchers are interested in determining if this sense relies on sensory information from
moving fingers reaching the parietal lobe.
Objectives:
- To determine the brain regions responsible for the sense of volition and the associated
sense of agency.
Eligibility:
- Healthy right-handed individuals between 18 and 55 years of age.
Design:
- The study will involve a screening visit and two testing visits. The screening visit
will last 30 minutes to 1 hour, and the testing visits will each last 3 to 4 hours.
- Participants will be screened with a physical examination and medical history.
- At each testing visit, participants will have a brain magnetic resonance imaging (MRI)
scan, electroencephalography (EEG), and electromyography (EMG). The MRI scan and EEG
will be done during a movement task that involves the thumb, second finger, and fifth
finger of one hand. EMG will be used to monitor movements and muscle activity.
- During the second testing visit, participants will receive a nerve block using
anesthetic, followed by the MRI, EEG, EMG and movement task. The nerve block will
temporarily numb and prevent the movement of parts of the hand and fingers.
- After the MRI scan and EEG recording, participants will be asked to rate how much
control they felt they had over choosing whether to move, and how much control they
felt they had in actually making the movements.
OBJECTIVE:
The primary objective of this study is to determine the brain regions responsible for the
sense of volition and the associated sense of agency. Nerve blocks will be used to
interfere with movement and/or sensory feedback from movement.
STUDY POPULATION:
Healthy subjects
DESIGN:
The initial studies will evaluate brain activity during the attempt to move different
fingers after ulnar nerve block using functional magnetic resonance imaging (fMRI),
electroencephalography (EEG) and surface electromyography (EMG). Subjects will attempt to
move their fifth finger, their second finger and the thumb. These fingers will also be
moved by the experimenter as a passive condition. The paradigm will be done once without
anesthesia and once after ulnar nerve block. For both fMRI, EEG and EMG, analysis will be
done with single event design. As our primary outcome, we hypothesize that subtracting the
activation associated with attempting to move a paralyzed and anesthetized 5th finger, as
well as the activation associated with the passive movement of the 5th finger without
anesthesia, from that of normal movement of the same finger (without anesthesia), will show
activation remaining in the inferior parietal lobule, which may be the area responsible for
the feeling of agency. The activation associated with the attempt to move second finger,
which will be paralyzed but only partially anesthetized, will be a secondary outcome of this
study, as will other subtractions of activation associated with the three fingers.
OUTCOME MEASURES:
fMRI: Comparison of the BOLD signal in different brain regions with the different finger
movements or attempted finger movements. The primary outcome measure is the difference in
BOLD activation in the inferior parietal lobule between that associated with the attempt to
move the 5th finger after anesthesia compared to the activation associated with moving the
5th finger actively minus the 5th finger being moved passively (with no anesthesia).
Restated, from the trial with no anesthesia, the activation of active 5th finger movement
(which reflects will (W), motor program (P), sensory feedback (S) and agency (A)) minus
passive 5th finger movement (which reflects S only) will be compared to the activation from
the attempt to move the 5th finger after ulnar block (which reflects W and P only). By
comparing (W+P+S+A minus S) to (W+P) in the region of the inferior parietal lobule, we
expect to see the activation associated with A, agency.
EEG/EMG: Movement-related cortical potentials will be compared with the different finger
movements, using EMG to mark the onset of movement; these will be secondary outcomes.
We found this trial at
1
site
9000 Rockville Pike
Bethesda, Maryland 20892
Bethesda, Maryland 20892
301-496-2563
National Institutes of Health Clinical Center The National Institutes of Health (NIH) Clinical Center in...
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