Emily A Keshner

Temple University | TU · Department of Physical Therapy

Balance perturbations are accompanied by global cortical activation that increases in magnitude when postural perturbations are unexpected, potentially due to the addition of a startle response. A specific site for best recording the response to unexpected destabilization has not been identified. We hypothesize that a single sensor located near to...

During the early years of spaceflight it was documented that astronauts were impaired and incapacitated upon return to earth. Computerized Dynamic Posturography (CDP) was devised to investigate and quantify this deficit, and eventually progressed into a clinical assessment tool. The current sprouting of virtual reality (VR) technologies has allowed...

Introduction: No reliable biometric measurement of vestibular involvement with migraine is currently available. Objective: Measures of autonomic nervous system and postural responses could serve as quantifiable indicators of vestibular involvement with migraine. Methods: A convenience sample of 22 young healthy adults (34±9 years old) and 23 y...

The ability to control head orientation relative to the body is a multisensory process that mainly depends on proprioceptive, vestibular, and visual sensory systems. A system to study the sensory integration of head orientation was developed and tested. A test seat with a five-point harness was assembled to provide passive postural support. A light...

Background No objective criteria exist for diagnosis and treatment of visual-vestibular mismatch (VVM). Objective To determine whether measures of electrodermal activity (EDA) and trunk acceleration will identify VVM when exposed to visual-vestibular conflict. Methods A modified VVM questionnaire identified the presence of VVM (+ VVM) in 13 of 23...

BACKGROUND No objective criteria exist for diagnosis and treatment of visual-vestibular mismatch (VVM). OBJECTIVE To determine whether measures of electrodermal activity (EDA) and trunk acceleration will identify VVM when exposed to visual-vestibular conflict. METHODS A modified VVM questionnaire identified the presence of VVM (+ VVM) in 13 of 23...

Dynamic systems theory transformed our understanding of motor control by recognizing the continual interaction between the organism and the environment. Movement could no longer be visualized simply as a response to a pattern of stimuli or as a demonstration of prior intent; movement is context dependent and is continuously reshaped by the ongoing...

Background: Dizziness affects 20-30%of the general population. A subgroup of dizzy patients with chronic migraine suffers vertigo implying that the migraine has a vestibular component. Vestibular migraine remains a diagnosis of exclusion based on history. Objective: A link between headaches and dizziness suggests that these individuals would dem...

Background The use of virtual reality (VR) in clinical settings has increased with the introduction of affordable, easy-to-use head-mounted displays (HMDs). However, some have raised concerns about the effects that HMDs have on posture and locomotion, even without the projection of a virtual scene, which may be different across ages. Research ques...

Background Diminished balance confidence increases the risk of a fall and falls that occur when turning during walking are associated with an eightfold increase in hip fractures compared to when walking in a straight trajectory. Although an effect of aging on turning is revealed, the role of gender during turning is not yet clear. Research Questio...

Background Older adults show greater postural instabilities under misleading visual cues relative to younger adults. We investigated the effects of age-related visual dependence on motor performance under increased attention demands by adding a motor task and visual stimulus to the Timed Up and Go (TUG) test sub-components. Method We designed a...

Background: Application of virtual reality (VR) to rehabilitation is relatively recent with clinical implementation very rapidly following technological advancement and scientific discovery. Implementation is often so rapid that demonstrating intervention efficacy and establishing research priorities is more reactive than proactive. This study use...

The presence of visual dependence as an influential factor on the development of functional stability in ambulatory individuals with cerebral palsy (CP) was studied in 22 adults with spastic bilateral CP, 11 of whom were considered visually dependent, and 18 healthy adults. Participants stood upright during pitch plane disturbances of the visual fi...

Gender plays a role in cognitive performance. Yet the selection of a secondary task, an important paradigm in studies of posture control, has not considered gender as a variable. We explored whether different cognitive tasks differentially influence performance during the Timed Up and Go (TUG) test in men and women. Twenty young adults performed fi...

The use of virtual reality in clinic settings is becoming more common given the availability of portable, easy to use head-mounted displays (HMDs). HMDs support virtual reality environments that are variable, motivating, yet safe to include in clinical assessment and interventions in different populations (Adamovich, Fluet, Tunik, & Merians, 2009;...

Falls in older adults are linked with increased morbidity and mortality, and remain a major public health concern. Aging is associated with increased reliance on the visual system for postural control, termed “visual dependence”. Discordance between visual, vestibular and proprioceptive sensory information can lead to balance loss and falls. In add...

The current study aimed to explore the impact of visual dependence on sensorimotor coupling of postural sway and visual motion in adults and teens with spastic cerebral palsy (CP). We hypothesized that individuals with CP would exhibit greater magnitudes of sway than healthy individuals, and the presence of visual dependence (VD) would produce inst...

The purpose of this project was to determine whether verbal interaction with a virtual clinician that produced gestures facilitated the use of meaningful gestures in the affected and unaffected upper extremity of individuals with aphasia. We hypothesized that active engagement with a virtual clinician that produces natural gestures will support the...

The papers that follow stem from a symposium presented at the International Society for Posture and Gait Research (ISPGR) in Seville, Spain, in July 2015. Four speakers were charged with presenting their methods of applying virtual reality (VR) technology to obtain meaningful rehabilitation outcomes. The symposium aims to explore characteristics of...

Introduction The relationship between visual field motion and intersegmental behavior during postural destabilization was explored. Individuals with cerebral palsy (CP) were separated through a rod and frame test into those with visual dependence (VD) or independence (VI) to determine whether reliance upon an allocentric reference frame alters the...

Purpose: We investigated the feasibility of using a virtual clinician to promote functional communication abilities of persons with aphasia (PWA). We aimed to determine whether the quantity and quality of verbal output in dialogues with a virtual clinician would be the same or greater than that with a human clinician. Method: Four individuals wi...

Background: Posturography systems that incorporate force platforms are considered to assess balance and postural control with greater sensitivity and objectivity than conventional clinical tests. The Wii Balance Board (WBB) system has been shown to have similar performance characteristics as other force platforms, but with lower cost and size. Ob...

Providing realistic stimuli has traditionally posed a challenge for virtual reality researchers. Most efforts have been done with visual information. Different technical solutions, such as head mounted displays and cave systems, have been presented through the years improving the state-of-the-art instrumentation. In recent years, an increasing inte...

The high cost and space required by laboratory grade posturography systems prevents their adoption in most clinics. We have developed a low-cost posturography system that is based on three different exercises commonly used in posturography testing and uses the Nintendo® Wii Balance Board™ as a force platform. This paper describes: a) a study of the...

The primary focus of rehabilitation for individuals with loss of upper limb movement as a result of acquired brain injury is the relearning of specific motor skills and daily tasks. This is essential because the loss of upper limb movement often results in a reduced quality of life. Although rehabilitation strives to take advantage of neuroplastic...

This chapter deals with the issue of resolving ambiguity between motion of objects in the world and self-motion that reflects the interdependence between multimodal signals. A growing body of evidence suggests that visual, vestibular, nonvisual, and non-vestibular aspects of virtual world immersion play an important role in self-motion perception....

This chapter reviews how VR can be used to investigate normal and disturbed mechanisms of balance and locomotor control. Loss of upright balance control resulting in falls is a major health problem for older adults and stroke survivors. Balance and mobility deficits arise not only from motor or sensory impairments but also from the inability to sel...

This chapter presents an overview of the evidence supporting effectiveness of VR for motor rehabilitation and a review of the major technological “breakthroughs” (1986–1995; 1996–2005; 2006-present) that led to the use of VR for motor rehabilitation. A “Force Field” analysis is presented that looks to the future regarding developments anticipated t...

The development of technologies that can be applied to rehabilitation offers tremendous promise for enhancing functional capacity by eliminating or minimizing the functional limitations imposed by disability. As new rehabilitation technologies emerge, it is our responsibility as scientists and clinicians to determine how these can best be used to s...

Underlying the increased incidence of falls during multitasking is a reduced ability to detect or attend to the sensory information signaling postural instability. Adding noise to a biological system has been shown to enhance the detection and transmission of weakened or sub-threshold cutaneous signals. If stochastic resonance is to become an effec...

We explored the trade-off between simultaneous demands of attention to a mental calculation task, visual motion, and postural stabilization. Six healthy adults (23 ± 0.97 yrs) performed a balance task and a secondary calculation task in a stationary or translating immersive virtual reality environment. Coupling of visual and base of support motion...

Visual field immersion and plantar vibration effects on balance were examined. Healthy adults stood quietly in a 3-wall immersive virtual environment (VE) and with a 3DTV for four trials while: barefoot, barefoot on foam, and wearing shoes on foam with and without sub-threshold plantar vibration. RMS of center of pressure velocity were significantl...

Aphasia is an acquired communication disorder that affects the ability to speak and understand spoken language. The purpose of this project is to create a virtual clinician to help individuals with aphasia practice self-initiated speech in everyday communication situations. The project will gauge the interaction and quality of this virtual clinicia...

We employed a virtual environment to examine the postural behaviors of adults with cerebral palsy (CP). Four adults with CP (22-32 years) and nine healthy adults (21-27 years) were tested with a Rod and Frame protocol. They then stood quietly on a platform within a three-wall virtual environment. The platform was either kept stationary or tilted 3...

This study intended to determine if an acute bout of soccer heading alters postural control and pronounced self-reported symptoms of cerebral concussion. Collegiate soccer players were randomly assigned to one of 2 groups. Each participant completed a baseline postural control assessment prior to heading. Participants either simulated (control grou...

Studies examining fear of falling among older adult men remain limited. The objectives of this study were to compare balance confidence in two age cohorts of older clergy and identify predictive determinants of balance confidence in a liturgical research initiative. Participants included 131 community-dwelling Roman Catholic priests aged 60-97 year...

We explored how changes in visual attention impacted postural motor performance in healthy elders and adults post-stroke within a virtual reality environment, including when vestibular information was not perceptible. Visual dependence in 13 healthy (50-80 years) and 13 adults post-stroke (49-70 years) was assessed with a rod-and-frame task. Three...

We present results from a series of studies that investigated how multimodal mismatches in a virtual environment modified postural response organization. Adaptation of motor commands to functional circumstances is driven directly by error signals. Thus, motor relearning should increase when performing in environments containing sensory mismatch. We...

Sensorimotor coordination relies on fine calibration of the interaction among visual, vestibular, and somatosensory input. Our goal was to investigate how the spatiotemporal properties of passive inertial motion and visual input affect head stabilization. Healthy young adults (n=12) wore a head-mounted display during A/P sinusoidal horizontal trans...

We employed a virtual environment to examine the effect of a visual field rotating about the interaural or talo- crural axes on postural behaviors in 11 healthy young adults. Subjects stood quietly in the dark or while the virtual scene rotated in upward pitch on a platform that tilted the ankle into dorsiflexion. Three orders of visual axis rotati...

We employed a virtual environment to examine the impact of visual sensitivity on postural behaviors in adults with chronic symptoms of stroke. Six adults at least 1 year post-stroke (52-70 yrs) and 6 healthy adults (50-70 yrs) were tested in a Rod and Frame test. They then stood quietly on a platform within a 3- wall virtual environment. The platfo...

The effect of continuous visual flow on the ability to regain and maintain postural orientation was examined. Fourteen young (20-39 years old) and 14 older women (60-79 years old) stood quietly during 3° (30°/s) dorsiflexion tilt of the support surface combined with 30° and 45°/s upward or downward pitch rotations of the visual field. The support s...

The purpose of using time-series analyses is to provide interpretation of information on curves or functions, such as dynamic, biomechanical data. We evaluated the application of one method of time-series analysis for assessing changes in postural responses when exposed to a continuously rotating visual field combined with a tilted support surface....

To examine the evolution of inter-segmental coordination over-time, a previously developed multivariate model of postural coordination during quiet stance by Kuo et al. [1,2] has been extended. In the original model, postural coordination was treated as an eigenvalue–eigenvector problem between two segmental degrees of freedom represented by angula...

In this paper, we report a robust, efficient, and automatic method for matching infrared tracked markers for human motion analysis in computer-aided physical therapy applications. The challenges of this task stem from non-rigid marker motion, occlusion, and timing requirements. To overcome these difficulties, we use pair-wise distance constraints f...

To stabilize our position in space we use visual information as well as non-visual physical motion cues. However, visual cues can be ambiguous: visually perceived motion may be caused by self-movement, movement of the environment, or both. The nervous system must combine the ambiguous visual cues with noisy physical motion cues to resolve this ambi...

To examine the evolution of inter-segmental coordination over time, a previously developed multi-variate model of postural coordination during quiet stance (Kuo et al. 1998) has been extended. In the original model, postural coordination was treated as an eigenvalue-eigenvector problem between two segmental degrees of freedom represented by angular...

In this study, we have explored whether the impact of visual information on postural reactions is due to the same perceptual mechanisms that produce vection. Pitch motion of the visual field was presented at varying velocities to eight healthy subjects (29.9+/-2.8 years) standing quietly on a stationary base of support or receiving a 3 degrees toes...

To compare the occurrence of visual field independence/dependence in healthy subjects with patients who are post-stroke using the Rod and Frame Test, and determine whether increased visual dependence is reflected in their postural responses when immersed in a moving visual environment. Eight older and twelve young adults, and twelve patients with c...

The effect of visual field motion on the sit-to-stand kinematics of adults and children was investigated. Children (8 to12 years of age) and adults (21 to 49 years of age) were seated in a virtual environment that rotated in the pitch and roll directions. Participants stood up either (1) concurrent with onset of visual motion or (2) after an immers...

We investigated how the velocity of anterior-posterior movement of a visual surround affected segmental kinematics during stance. Ten healthy young adults were exposed to sinusoidal oscillation of an immersive virtual scene at five peak velocities ranging from 1.2 to 188 cm/s at each of four frequencies: 0.05, 0.1, 0.2 and 0.55 Hz. Root mean square...

Children and adults stood from a seated position in the dark, with the onset of visual scene motion or after a period of immersion in the virtual reality environment. Multiplanar head and trunk angular velocity were calculated. Both children and adults were found to reduce head and trunk angular velocities when immersed in a moving visual field but...

This study examines whether combining a sustained mechanical and visual disturbance will modify the automatic postural responses and alter subsequent recovery to vertical orientation in healthy young and older adults and in patients who are post-stroke. Subjects stood on a platform that tilted 3 deg at 30 deg/sec into dorsiflexion while in the dark...

This paper looks into the influence of cerebellar disease and bilateral vestibular deficit along with visual inputs on head stabilization during a-p oscillatory linear acceleration at 0.60, 0.81, and 1.11 Hz. The results may infer that at these frequencies the system mechanism instead of voluntary movement, VCR and CCR dominates the head stabilizat...

Orientation in space is a perceptual variable intimately related to postural orientation that relies on visual and vestibular signals to correctly identify our position relative to vertical. We have combined a virtual environment with motion of a posture platform to produce visual-vestibular conditions that allow us to explore how motion of the vis...

Instability is a significant risk factor for falls in individuals with a bilateral labyrinthine deficit. The purpose of this case report is to describe an intervention that we found to improve balance in a patient with bilateral labyrinthine deficit using a training paradigm based on the sensory reweighting hypothesis. The participant was a female...

The goal of this book is to bring together ideas from several different disciplines in order to examine the focus and aims that drive rehabilitation intervention and technology development. Specifically, the chapters in this book address the questions of what research is currently taking place to further develop rehabilitation, applied technology a...

The impaired balance of posture accounts for the fall with a large proportion of falls in older people occurring when walking. However, the mechanisms underlying impaired balance during both gait and passive postural state are poorly understood. The objective of the research is to examine the underlying causes of instability and then to eventually...

Reaching toward a visual target involves the transformation of visual information into appropriate motor commands. Complex movements often occur either while we are moving or when objects in the world move around us, thus changing the spatial relationship between our hand and the space in which we plan to reach. This study investigated whether rota...

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We investigated the manner in which complementary and conflicting visual and physical motion signals affect postural responses in healthy elderly individuals vs. an age-matched group that had experienced cortical or subcortical strokes (stroke). Subjects stood on a motion platform located within a virtual reality environment and were asked to maint...

Orientation of the body has been shown to adapt to sustained stance on a tilted support surface in subjects who were blindfolded or who had their eyes closed. Postural adaptation occurs even when the lower limbs are constrained, suggesting that there is central adaptation of the perception of vertical. These studies, however, were performed in the...

One of the most pervasive disabilities is postural instability because it can arise with changes in both the central and peripheral nervous systems and in the skeletal-muscular system. In this keynote address, I will explore the role that virtual environment technology (VE) can play in the assessment and treatment of balance disorders and highlight...

Multiplanar environmental motion could generate head instability, particularly if the visual surround moves in planes orthogonal to a physical disturbance. We combined sagittal plane surface translations with visual field disturbances in 12 healthy (29-31 years) and 3 visually sensitive (27-57 years) adults. Center of pressure (COP), peak head angl...

DefinitionThe time-derivative of the velocity vector of a specific particle. For a material body, at each instant of time there exists an acceleration field, namely an acceleration vector assigned to each particle of the body.MechanicsMeasurement Techniques

The purpose of this study was to determine how visual context affects intersegmental coordination during a postural stabilization task in older adults who are healthy or who have bilateral labyrinthine deficiency. Six healthy elderly (60-78 yrs) and 3 labyrinthine deficient (59-86 yrs) adults stood on a platform translating sinusoidally (plusmn10 c...

To determine if increased visual dependence can be quantified through its impact on automatic postural responses, we have measured the combined effect on the latencies and magnitudes of postural response kinematics of transient optic flow in the pitch plane with platform rotations and translations. Six healthy (29-31 yrs) and 4 visually sensitive (...

Planning and execution of reaching requires a series of computational processes that involve localization of both the target and initial arm position, and the translation of this spatial information into appropriate motor commands that bring the hand to the target. We have investigated the effects of shifting the visual field on visuomotor control...

New technologies are rapidly having a great impact on the development of novel rehabilitation interventions. One of the more popular of these technological advances is virtual reality. The wide range of applications of this technology, from immersive environments to tele-rehabilitation equipment and care, lends versatility to its use as a rehabilit...

We previously reported responses to induced postural instability in young healthy individuals viewing visual motion with a narrow (25 degrees in both directions) and wide (90 degrees and 55 degrees in the horizontal and vertical directions) field of view (FOV) as they stood on different sized blocks. Visual motion was achieved using an immersive vi...