Balancing sensory inputs: Sensory reweighting of ankle proprioception and vision during a bipedal posture task.

During multisensory integration, it has been proposed that the central nervous system (CNS) assigns a weight to each sensory input through a process called sensory reweighting. The outcome of this integration process is a single percept that is used to control posture. The main objective of this study was to determine the interaction between ankle proprioception and vision during sensory integration when the two inputs provide conflicting sensory information pertaining to direction of body sway.

Hemodynamic function during finger force production tasks in healthy adults.

Introduction: Near-infrared spectroscopy (NIRS) is a noninvasive technique used to measure muscle hemodynamics. The focus of this study was to evaluate changes in muscle oxygenation during sustained maximal force production in young, healthy control individuals to establish baseline function in an ideal population.

Methods: NIRS was used to monitor reduced hemoglobin (HbR) and oxygenated hemoglobin (HbO) in forearm muscles.

Cortical activity modulations underlying age-related performance differences during posture-cognition dual tasking.

To date, no systematic research investigating cortical correlates of performance changes in dual tasking has been reported in the elderly population. Thus, we monitored whole-scalp cortical activations (EEG) during both single task and posture-cognition dual tasking with the main goal of understanding cortical activity modulations underlying age-related differences on posture-cognition dual tasking conditions. Postural and cognitive data analyses showed that elderly people had decreased cognitive performance even during challenging single cognitive tasks.

Contribution of tactile dysfunction to manual motor dysfunction in type II diabetes.

Introduction: Changes in sensory and motor functions of the hand in type II diabetes (T2D) patients have been reported; there is speculation that these changes are driven by tactile dysfunction. The purpose of this study was to evaluate the effects of tactile feedback on manual function in T2D patients.

Methods: T2D patients and healthy controls underwent median nerve blocks at the wrist and elbow.

Vibrotactile cuing revisited to reveal a possible challenge to sensorimotor adaptation.

Motor responses to unexpected external perturbations require the adjustment of the motor commands driving the ongoing activity. Strategies can be learned with practice to compensate for these unpredictable perturbations (e.g.

Associations between Tactile Sensory Threshold and Postural Performance and Effects of Healthy Aging and Subthreshold Vibrotactile Stimulation on Postural Outcomes in a Simple Dual Task.

Specific activities that require concurrent processing of postural and cognitive tasks may increase the risk for falls in older adults. We investigated whether peripheral receptor sensitivity was associated with postural performance in a dual-task and whether an intervention in form of subthreshold vibration could affect performance. Ten younger (age: 20-35 years) and ten older adults (70-85 years) performed repeated auditory-verbal 1-back tasks while standing quietly on a force platform.

Effects of tibialis anterior vibration on postural control when exposed to support surface translations.

The sensory re-weighting theory suggests unreliable inputs may be down-weighted to favor more reliable sensory information and thus maintain proper postural control. This study investigated the effects of tibialis anterior (TA) vibration on center of pressure (COP) motion in healthy individuals exposed to support surface translations to further explore the concept of sensory re-weighting. Twenty healthy young adults stood with eyes closed and arms across their chest while exposed to randomized blocks of five trials.

Validity and reliability of two protocols for measuring Reachable Workspace Volume in able-bodied and stroke subjects.

Background: Researchers are measuring Reachable Workspace Volume (RWV) to assess the effects of various interventions on impaired upper extremity function. These measurement protocols have not been validated.

Objective: Assess the validity and reliability of two RWV protocols.

Motor Control Performance During Rapid Voluntary Movements of Elbow and Knee.

Knowledge of motor control differences during rapid goal-directed movements of the upper and lower limbs could be useful in improving rehabilitation protocols. The authors investigated performance and control differences between elbow and knee joints and between different contraction types (concentric vs. eccentric) during rapid movements under externally applied load.

Effects of adiposity on postural control and cognition.

In the U.S., it is estimated that over one-third of adults are obese (Body Mass Index (BMI)>30kg/m(2)).

Smartphone-based tactile cueing improves motor performance in Parkinson's disease.

Introduction: Visual and auditory cueing improve functional performance in Parkinson's disease (PD) patients. However, audiovisual processing shares many cognitive resources used for attention-dependent tasks such as communication, spatial orientation, and balance. Conversely, tactile cues (TC) may be processed faster, with minimal attentional demand, and may be more efficient means for modulating motor-cognitive performance.

Effects of Force Requirements on Pinch Force Production in Healthy Adults.

Previous studies of fine motor control have focused on the ability of participants to match their grip force production to a visually provided template. We investigated differences exhibited in pinch force control during variable force production templates, including sine-, sawtooth-, and square-wave templates. Our results indicate that increased force requirements are associated with increased error rates and a noisier frequency spectrum, consistent with previous studies.

The effects of different sensory augmentation on weight-shifting balance exercises in Parkinson's disease and healthy elderly people: a proof-of-concept study.

Background: Earlier versions of biofeedback systems for balance-related applications were intended primarily to provide "alarm" signals about body tilt rather than to guide rehabilitation exercise motion. Additionally, there have been few attempts to evaluate guidance modalities for balance rehabilitation exercises. The purpose of this proof-of-concept study is to evaluate the effects of guidance modalities during common dynamic weight-shifting exercises used in clinical settings.

Using nonlinear tools to evaluate movement of fragile objects.

We investigated the movement strategies of young, healthy participants (7 men/7 women) during the movement of a fragile object using nonlinear analysis. The kinematic variables of position, velocity, and acceleration were quantified using largest Lyapunov exponent (LyE) and approximate entropy (ApEn) analysis to identify the structure of their movement variability and movement predictability, respectively. Subjects performed a total of 15 discrete trials of an upper extremity movement task without crushing the object at each fragility condition, using each hand (left/right).

Effects of an artificial gravity countermeasure on orthostatic tolerance, blood volumes and aerobic power after short-term bed rest (BR-AG1).

Exposure to artificial gravity (AG) in a short-arm centrifuge has potential benefits for maintaining human performance during long-term space missions. Eleven subjects were investigated during three campaigns of 5 days head-down bed rest: 1) bed rest without countermeasures (control), 2) bed rest and 30 min of AG (AG1) daily, and 3) bed rest and six periods of 5 min AG (AG2) daily. During centrifugation, the supine subjects were exposed to AG in the head-to-feet direction with 1 G at the center of mass.

Changes in sensory function and force production in adults with type II diabetes.

Introduction: The purpose of this study was to evaluate the relationship among sensory function, disease severity, and upper extremity force production in adults with type II diabetes (T2D) as compared with healthy age- and gender-matched controls.

Methods: Ten adults with T2D and 10 healthy age- and gender-matched control subjects underwent a battery of sensory and motor function evaluations. Data on disease severity and duration were also collected.

Strength and endurance adaptations to functional electrical stimulation leg cycle ergometry in spinal cord injury.

Objectives: To describe adaptations in power output, quadriceps muscle strength, and fatigability that occur during a 13-week regimen of Functional Electrical Stimulation Leg Cycle Ergometry (FES-LCE) in Spinal Cord Injury (SCI). To identify differences in outcomes between individuals with complete and incomplete motor impairment.

Design: Observational and longitudinal.

Sensorimotor posture control in the blind: superior ankle proprioceptive acuity does not compensate for vision loss.

To better understand sensorimotor posture control differences between blind and sighted individuals, we examined the role of ankle joint proprioception and ankle muscle strength on postural control in healthy blind (n=13, 25-58 years) and age- and sex-matched sighted (n=15, 20-65 years) volunteers. We measured ankle joint proprioceptive acuity and isokinetic muscle strength in plantarflexion and dorsiflexion using an isokinetic dynamometer. We also assessed postural control performance during quiet bipedal stance with and without sudden postural perturbations, and during quiet unipedal stance.

Societal costs of intrathecal drug delivery systems--an administrative analysis based on patient claims.

Objectives: To quantify the overall and disaggregated societal costs of intrathecal drug delivery systems (IDDSs) in the treatment of pain and spasticity in the United States.

Materials And Methods: A retrospective review of medical and pharmacy claims was performed on patients with IDDS. Patients were divided into three cohorts according to the conditions that their IDDSs were intended to treat pain, spasticity, or both.

Muscle function during takeoff and landing flight in the pigeon (Columba livia).

This study explored the muscle strain and activation patterns of several key flight muscles of the pigeon (Columba livia) during takeoff and landing flight. Using electromyography (EMG) to measure muscle activation, and sonomicrometry to quantify muscle strain, we evaluated the muscle function patterns of the pectoralis, biceps, humerotriceps and scapulotriceps as pigeons flew between two perches. These recordings were analyzed in the context of three-dimensional wing kinematics.

Classification of rhythmic locomotor patterns in electromyographic signals using fuzzy sets.

Background: Locomotor control is accomplished by a complex integration of neural mechanisms including a central pattern generator, spinal reflexes and supraspinal control centres. Patterns of muscle activation during walking exhibit an underlying structure in which groups of muscles seem to activate in united bursts. Presented here is a statistical approach for analyzing Surface Electromyography (SEMG) data with the goal of classifying rhythmic "burst" patterns that are consistent with a central pattern generator model of locomotor control.

Parkinson's disease influences the structural variations present in the leg swing kinematics.

This study investigated the nature of the structural variations found in the motor output of individuals with Parkinson's disease (PD). Young (n = 21; 19.9 ± 1.

Variations in linear and nonlinear postural measurements under achilles tendon vibration and unstable support-surface conditions.

Reduced support-surface stability has been shown to attenuate the effect of Achilles tendon vibration on backward body displacement. In the present study, 20 participants performed a quiet, upright standing task on a stable and sway-referenced support, with and without vibration. The authors calculated equilibrium scores (ES), approximate entropy (ApEn), and mean and peak power spectral density frequencies of center-of-pressure variations.