This study will use functional magnetic resonance imaging (MRI) to examine loss of balance
in the elderly. Falls due to balance problems are a major health issue in older people,
often resulting in bone fractures and other bodily injuries, and in functional decline.
Risk factors for falling in the elderly include some standing positions in which older
people usually experience balance problems, such as leaning forwards or backwards.
Functional MRI records brain function while the subject performs a task, such as moving a
limb or speaking, and detects changes in the brain regions involved in those tasks. This
study will look at different brain areas to see which areas might control what people see
around them while they are standing.
Healthy normal volunteers between 20 and 90 years of age may be eligible for this study.
Candidates must be in good health, have no difficulties in performing activities of daily
living, and be able to walk for at least 400 meters (1/4 mile). They will be screened with
a medical history and physical examination.
Participants will undergo functional MRI while performing visual recognition tasks in two
experiments, described below. For the MRI procedure, the subject lies in the MRI scanner, a
narrow metal cylinder containing a strong magnet, for 20 minutes to 3 hours, with most scans
lasting between 45 and 90 minutes. The experiments are as follows:
During MRI scanning, the subject watches computer-generated movies of a person leaning
forwards and backwards. When the subject recognizes an unstable body position in the
movements, he or she presses a computer mouse.
During MRI scanning, the subject watches still pictures of people leaning in stable and
unstable postures and presses a button as soon as he or she recognizes that the posture is
A number of studies have explored the role of visual, vestibular and somatosensory systems
in the control of upright posture. However, the cortical control of postural stability, in
general, and the role of higher cognitive function in assessment of postural stability, in
specific, has not been studied extensively. It is well established that certain features of
postural control change during the advancing years of life so that the stability of posture
can be a problem in the elderly. However, neural mechanisms of postural stability that
decline with age and make older adults more prone to falling have not been identified
specifically. To characterize specific causes of falling in the elderly is problematic,
because human posture is a product of an extremely complex dynamical system and like any
other physical activity undergoes dramatic changes in organization throughout the life-span.
In our previous research we showed the neural activation patterns embodied in the
electroencephalogram (EEG) were associated with recognition of unstable postures in young
healthy subjects. In another protocol, we propose that these patterns will systematically
change with aging, and will result in difficulty to discriminate relevant from irrelevant
information in the control of upright posture. The present study focuses on the evaluation
of neural activation patterns underlying recognition of unstable postures in 15 young
controls and 15 elderly subjects using both the block and event-related functional MRI
(fMRI) designs. We will first analyze how the frontal-parieto-occipital circuits play a
role in perception of postural stability in young subjects and then perform similar studies
using elderly subjects. After the fMRI measurements a detailed evaluation of the
haemodynamic response (BOLD) signals will be performed. Further analysis will look at the
functional connectivity between the motion-selective cortical area (V5), the posterior
parietal cortex (PP) and the frontal cortex (FC), using correlation methods. It is expected
that from the study will uncover important insights in neural mechanisms as it relates to
the self-perception of postural stability and its deterioration as a result of aging.
There will be 20 subjects in each aforementioned age group.
Subjects will be enrolled in this study if they are within the range of 20-50 (young
group) and 70-90 (old group) years old, in good health, report no difficulties or need for
help in performing self-care or instrumental activities of daily living, are able to walk
for at least 400 meters.
All subjects and patients participating in this study will have a valid Clinical Center
Medical Record Number.
We will be unable to study people who have substantial cognitive impairment based on
mental status screening tests, history of cardiovascular disease (including angina,
myocardial infarction, congestive heart failure, cerebro-vascular disease), cancer,
neurological diseases, birth defects, kidney or liver disease, gastrointestinal (G.I.)
disease, musculo-skeletal disorder (if they cause pathological weakness and/or chronic
pain), important sensory deficits and any conditions that precludes them from being tested
with standard neuropsychological tests.
MRI experiments will not be performed in subjects or patients who have pacemakers, brain
stimulators, dental implants or metallic braces, aneurysm clips (metal clips on the wall
of a large artery), metallic prostheses (including metal pins and rods, heart valves, and
cochlear implants), permanent eyeliner, insulin pump, or shrapnel fragments.
We will not scan pregnant women because of the safety of high magnetic fields to the fetus
is not established.