Document text
Principal Investigator: Amir Kheradmand
Organization: JOHNS HOPKINS UNIVERSITY
Fiscal Year: 2024
Award: $149,880
Funding agency: National Institute on Aging
Spatial perception is based on various sensory inputs processed within a widely-distributed cerebral network. Cur-
rently it is not known how these multisensory mechanisms and their contributions to spatial orientation are affected
by aging. Clinical histories in elderly frequently entail experiences of spatial misperceptions with sudden feelings of
imbalance or tilt that can lead to injuries that are highly morbid and costly. Here we combine psychophysics and
mathematical modelling to investigate age-related changes in these ‘high order’ mechanisms. We have studied
spatial orientation in the context of Bayesian spatial model (BSM), which incorporates the sensory signals that
encode the head and eye positions to quantify perceived upright orientation. Accordingly, the signal-to-noise ratio
in each sensory modality affects its reliability for integration into an internal (i.e., neural) estimate that contributes
to spatial orientation. In this novel approach, sensory contributions are measured directly in psychophysical para-
digms. In this proposal, we apply the same approach within the quantitative BSM framework to study changes in
spatial orientation with aging. We’ve found individuals with vestibular loss have a bias in spatial orientation related
to underestimation of their head position. With aging, there is also sensory loss in the vestibular system that can
lead to problems with balance and spatial orientation by affecting how the brain reweights sensory information to
compensate for such changes. This reweighting process is important to understand for devising diagnostic tools
and rehabilitation/treatment programs preferably at the individual subject level. On this basis, our central hypothesis
is that in the process of sensory integration for spatial orientation, older individuals underestimate their eye and
head positions, resulting in larger errors of spatial orientation and more postural instability compared with younger
individuals. To test this hypothesis, we (i) parse out sensory contributions to spatial orientation in aging, and (ii)
examine whether they correspond with age-related vestibular physiologic changes and fall risk. A key vestibular
input is from the otoliths that contributes to wide range of neurophysiologic functions such as sensing the head
motion with respect to gravity and it also drives the vestibulo-ocular response known as the ocular counter roll
(OCR). We have developed a video-oculography measure of OCR (vOCR), which is done with a simple tilt maneu-
ver. Here we also examine whether vOCR can be used as a biomarker of age-related changes in spatial orientation,
postural stability, and fall risk. Overall, this approach gives us a unique opportunity to apply our current research
work towards elucidating sensory contributions to changes in spatial orientation with aging. The key developments
in this proposal are identifying distinct changes in spatial orientation and examining a clinical measure of otolith
function as potential biomarker to assess and track age-related perceptual and balance functions.
Terms: <65 and older><65 or older><65 years of age and older><65 years of age or more><65 years of age or older><65+ years><65+ years old><> 65 years><Address><Affect><Aged 65 and Over><Aging><Bayesian Modeling><Bayesian adaptive designs><Bayesian adaptive models><Bayesian belief network><Bayesian belief updating model><Bayesian framework><Bayesian hierarchical model><Bayesian network model><Bayesian nonparametric models><Bayesian spatial data model><Bayesian spatial image models><Bayesian spatial models><Bayesian statistical models><Bayesian tracking algorithms><Biological Markers><Brain><Brain Nervous System><Cell Communication and Signaling><Cell Signaling><Cerebrum><Clinical><Clinical Evaluation><Clinical Testing><Compensation><Cues><Dependence><Development><Disorientation><Dizziness><Elderly><Encephalon><Equilibrium><Eye><Eyeball><Feeling><Force of Gravity><Gravities><Head><History><Human><Individual><Injury><Intracellular Communication and Signaling><Link><Math Models><Measurement><Measures><Medical Rehabilitation><Methods><Modality><Modern Man><Motion><Musculoskeletal Equilibrium><Natural Source><Noise><Older Population><Otoliths><Patients><Perception><Physiologic><Physiological><Physiology><Population><Position><Positioning Attribute><Postural Balance><Postural Equilibrium><Posture><Process><Process Measure><Psychophysics><Recording of previous events><Rehabilitation><Rehabilitation therapy><Research><Risk Factors><Sensory><Sensory Process><Signal Transduction><Signal Transduction Systems><Signaling><Space Perception><Spatial Discrimination><Statoconia><Testing><Uncertainty><Vestibular><Vestibular Diseases><Vestibular System Function><Vestibular disorder><Vestibular function><Vestibular loss><Vestibular system disorder><Vestibulopathy><Visual><Visuospatial><Work><above age 65><advanced age><after age 65><age 65 and greater><age 65 and older><age 65 or older><age > 65><age associated><age associated alterations><age associated biomarkers><age associated changes><age associated effects><age associated marker><age correlated><age correlated alterations><age correlated changes><age dependent><age dependent alterations><age dependent changes><age effect><age linked><age marker><age of 65 years onward><age related><age related alterations><age related biomarkers><age related changes><age related effects><age related markers><age specific><age specific alterations><age specific changes><aged 65 and greater><aged 65+><aged ≥65><aging effect><alterations with age><balance><balance function><bio-markers><biologic marker><biological markers of age><biological signal transduction><biomarker><biomarkers of age><body position><cerebral><changes with age><clinical test><co-morbid><co-morbidity><comorbidity><cost><developmental><diagnostic tool><disabling symptom><doubt><effective therapy><effective treatment><experience><eye tracking><fall risk><falls><feelings><geriatric><haptics><high risk><histories><human old age (65+)><impact of age><influence of age><injuries><mathematic model><mathematical model><mathematical modeling><multisensory><neural><neurophysiological><neurophysiology><new approaches><novel><novel approaches><novel strategies><novel strategy><old age><older adult><older adulthood><older groups><older individuals><older person><otoconia><otocyst><over 65 years><perceptual spatial orientation><personalization of treatment><personalized medicine><personalized therapy><personalized treatment><postural control><posture instability><potential biological marker><potential biomarker><psychophysical><rehab strategy><rehab therapy><rehabilitation strategy><rehabilitative><rehabilitative therapy><research clinical testing><response><senior citizen><sensory input><sensory integration><sensory mechanism><spatial integration><spatial orientation><spatial perception><treatment program><treatment strategy><vestibular system><visual spatial><visual tracking><≥65 years>