Magnetic Resonance Imaging and Nuclear Imaging of Parkinsonian Disorders: Where do we go from here?

Parkinsonian disorders are a heterogeneous group of incurable neurodegenerative diseases that significantly reduce quality of life and constitute a substantial economic burden. Nuclear imaging (NI) and magnetic resonance imaging (MRI) have played and continue to play a key role in research aimed at understanding and monitoring these disorders. MRI is cheaper, more accessible, nonirradiating, and better at measuring biological structures and hemodynamics than NI.

Distinct cortical and subcortical predictors of Purdue Pegboard decline in Parkinson's disease and atypical parkinsonism.

Objective measures of disease progression are critically needed in research on Parkinson's disease (PD) and atypical Parkinsonism but may be hindered by both practicality and cost. The Purdue Pegboard Test (PPT) is objective, has high test-retest reliability, and has a low cost. The goals of this study were to determine: (1) longitudinal changes in PPT in a multisite cohort of patients with PD, atypical Parkinsonism, and healthy controls; (2) whether PPT performance reflects brain pathology revealed by neuroimaging; (3) quantify kinematic deficits shown by PD patients during PPT.

Behavioral Classification of Sequential Neural Activity Using Time Varying Recurrent Neural Networks.

Shifts in data distribution across time can strongly affect early classification of time-series data. When decoding behavior from neural activity, early detection of behavior may help in devising corrective neural stimulation before the onset of behavior. Recurrent Neural Networks (RNNs) are common models for sequence data.

Unraveling somatotopic organization in the human brain using machine learning and adaptive supervoxel-based parcellations.

In addition to the well-established somatotopy in the pre- and post-central gyrus, there is now strong evidence that somatotopic organization is evident across other regions in the sensorimotor network. This raises several experimental questions: To what extent is activity in the sensorimotor network effector-dependent and effector-independent? How important is the sensorimotor cortex when predicting the motor effector? Is there redundancy in the distributed somatotopically organized network such that removing one region has little impact on classification accuracy? To answer these questions, we developed a novel experimental approach. fMRI data were collected while human subjects performed a precisely controlled force generation task separately with their hand, foot, and mouth.

Diffusion Magnetic Resonance Imaging Detects Progression in Parkinson's Disease: A Placebo-Controlled Trial of Rasagiline.

Background: Rasagiline has received attention as a potential disease-modifying therapy for Parkinson's disease (PD). Whether rasagiline is disease modifying remains in question.

Objective: The main objective of this study was to determine whether rasagiline has disease-modifying effects in PD over 1 year.

Exploration of a novel physical therapy protocol that uses a sensory substitution device to improve the standing postural balance of children with balance disorders.

Objective: To explore if an intensive balance training protocol that incorporated the BrainPort sensory substitution device improves the standing postural balance of children with balance disorders.

Methods: Eight children with balance disorders received 8-weeks of balance training while using the BrainPort device. Pre- and post-intervention changes in the Bruininks-Oseretsky Test of Motor Proficiency balance subtest (BOT-2) scores, standing duration on an unstable surface, and center of pressure (COP) sway were assessed.

Gamma somatosensory cortical oscillations are attenuated during the stance phase of human walking.

It is well appreciated that processing of peripheral feedback by the somatosensory cortices plays a prominent role in the control of human motor actions like walking. However, very few studies have actually quantified the somatosensory cortical activity during walking. In this investigation, we used electroencephalography (EEG) and beamforming source reconstruction methods to quantify the frequency specific neural oscillations that are induced by an electrical stimulation that is applied to the right tibial nerve under the following experimental conditions: 1) sitting, 2) standing in place, and 3) treadmill walking.

The Strength of the Movement-related Somatosensory Cortical Oscillations Differ between Adolescents and Adults.

Adolescents demonstrate increasing mastery of motor actions with age. One prevailing hypothesis is that maturation of the somatosensory system during adolescence contributes to the improved motor control. However, limited efforts have been made to determine if somatosensory cortical processing is different in adolescents during movement.

Optimizing Neuromuscular Electrical Stimulation Pulse Width and Amplitude to Promote Central Activation in Individuals With Severe Spinal Cord Injury.

Neuromuscular electrical stimulation (NMES) is one of the most effective treatments for counteracting the deleterious skeletal muscle adaptations that occur after spinal cord injury (SCI). Additionally, previous findings suggest that NMES can activate motor units both peripheral and central mechanisms; however, this NMES-promoted central activation is not well understood. In this study, we aimed at investigating the effects of NMES on central activation in 10 individuals with motor complete SCI, focusing on understanding how to optimize NMES pulse width and amplitude for promoting central activation in this population.

Practice modulates motor-related beta oscillations differently in adolescents and adults.

Key Points: Magnetoencephalography data were acquired during a leg force task in pre-/post-practice sessions in adolescents and adults. Strong peri-movement alpha and beta oscillations were mapped to the cortex. Following practice, performance improved and beta oscillations were altered.

Submaximal Marker for Investigating Peak Muscle Torque Using Neuromuscular Electrical Stimulation after Paralysis.

Spinal cord injury (SCI) results in deleterious skeletal muscle adaptations, such as relevant atrophy and loss of force. In particular, the relevant loss of lower-limb force-generating capacity may limit functional mobility even if neuronal control was sufficient. Currently, methods of assessing maximal force-generating capacity using neuromuscular electrical stimulation (NMES) are limited in individuals who cannot tolerate higher stimulation amplitudes, such as those with residual sensation and those at risk of fracture.

Neurophysiological changes in the visuomotor network after practicing a motor task.

Although it is well appreciated that practicing a motor task updates the associated internal model, it is still unknown how the cortical oscillations linked with the motor action change with practice. The present study investigates the short-term changes (e.g.

Movement-Related Somatosensory Activity Is Altered in Patients with Multiple Sclerosis.

During active movement the somatosensory cortical responses are often attenuated. This attenuation is referred to as movement-related sensory gating. It is well known that patients with multiple sclerosis (MS) have sensory processing deficits, and recent work has also suggested that these patients display impaired motor control of the ankle musculature.

Changes in lower extremity strength may be related to the walking speed improvements in children with cerebral palsy after gait training.

Background: Cerebral palsy (CP) has a high probability of resulting in lower extremity strength and walking deficits. Numerous studies have shown that gait training has the potential to improve the walking abilities of these children; however, the factors governing these improvements are unknown.

Aims: This study aimed to evaluate the relationship between change in lower extremity strength, walking speed and endurance of children with CP following gait training.

A reduced somatosensory gating response in individuals with multiple sclerosis is related to walking impairment.

When identical stimuli are presented in rapid temporal succession, neural responses to the second stimulation are often weaker than those observed for the first. This phenomenon is termed sensory gating and is believed to be an adaptive feature that helps prevent higher-order cortical centers from being flooded with unnecessary information. Recently, sensory gating in the somatosensory system has been linked to deficits in tactile discrimination.

Altered sensorimotor cortical oscillations in individuals with multiple sclerosis suggests a faulty internal model.

Multiple sclerosis (MS) is a demyelinating disease that results in a broad array of symptoms, including impaired motor performance. How such demyelination of fibers affects the inherent neurophysiological activity in motor circuits, however, remains largely unknown. Potentially, the movement errors associated with MS may be due to imperfections in the internal model used to make predictions of the motor output that will meet the task demands.

Two Different Types of High-Frequency Physical Therapy Promote Improvements in the Balance and Mobility of Persons With Multiple Sclerosis.

Objective: To evaluate the mobility and postural balance improvements that could be achieved in a cohort of persons with multiple sclerosis (MS) who participated in a motor adaptation protocol and a cohort of persons with MS who participated in a therapeutic exercise protocol.

Design: A cohort design, where subjects were evaluated before and after a 6-week intervention period.

Setting: Clinical laboratory setting.

Developmental Trajectory of Beta Cortical Oscillatory Activity During a Knee Motor Task.

There is currently a void in the scientific literature on the cortical beta oscillatory activity that is associated with the production of leg motor actions. In addition, we have limited data on how these cortical oscillations may progressively change as a function of development. This study began to fill this vast knowledge gap by using high-density magnetoencephalography to quantify the beta cortical oscillatory activity over a cross-section of typically developing children as they performed an isometric knee target matching task.

Multiple sclerosis influences the precision of the ankle plantarflexon muscular force production.

Objective: To quantify the precision of the steady-state isometric control of the ankle plantarflexors musculature of individuals with multiple sclerosis (MS), and to evaluate if the precision is related to the mobility impairments.

Methods: Individuals with MS and healthy adults performed a submaximal steady-state isometric contraction with the ankle plantarflexors. The coefficient of variation was used to assess the amount of variability or error in the precision of the torques generated by the ankle plantarflexor musculature.

Cue-related Temporal Factors Modulate Movement-related Beta Oscillatory Activity in the Human Motor Circuit.

In humans, there is a strong beta (15-30 Hz) event-related desynchronization (ERD) that begins before movement, which has been tentatively linked to motor planning operations. The dynamics of this response are strongly modulated by whether a pending movement is cued and the inherent parameters of the cue. However, previous studies have focused on the information content of cues and not on parameters such as the timing of the cue relative to other events.

Dissipation of disturbances seen in the knee joint kinematics of children with cerebral palsy.

Purpose: Children with cerebral palsy (CP) often use a crouch gait pattern that has disturbances in the knee joint kinematics. Although the length and rate of lengthening of the hamstring musculature have been speculated to be the reason that these disturbances are not adequately dissipated, this relationship has not been adequately explored. The purpose of this exploratory investigation was to use simulations of a musculoskeletal model and Floquet analysis to evaluate how the performance of hamstrings musculature during gait may be related to the knee joint instabilities seen in children with CP.

Neurorehabilitation Strategies Focusing on Ankle Control Improve Mobility and Posture in Persons With Multiple Sclerosis.

Background And Purpose: The neuromuscular impairments seen in the ankle plantarflexors have been identified as a primary factor that limits the mobility and standing postural balance of individuals with multiple sclerosis (MS). However, few efforts have been made to find effective treatment strategies that will improve the ankle plantarflexor control. Our objective was to determine whether an intensive 14-week neurorehabilitation protocol has the potential to improve the ankle plantarflexor control of individuals with MS.

Improving the motor skill of children with posterior fossa syndrome: a case series.

Children who receive treatment for medulloblastoma have a high survival rate, but also a high likelihood of developing posterior fossa syndrome, a condition that includes devastating balance and motor problems. This case series used 2 novel neuromodulation devices in conjunction with an intensive physical therapy intervention for 2 children who were 5 years post tumor treatment with a diagnosis of posterior fossa syndrome. Pre- and postclinical measures, in addition to magnetoencephalography brain imaging, describe positive behavioral and neuroplastic changes resulting from the intervention.

An fNIRS exploratory investigation of the cortical activity during gait in children with spastic diplegic cerebral palsy.

Objective: The primary aim of this exploratory investigation was to determine if there are differences in cortical activation of children with spastic diplegic cerebral palsy (CP) and typically developing children during gait.

Methods: Functional near-infrared spectroscopy was used to measure the concentration of oxygenated hemoglobin that was present in the supplementary motor area, pre-central gyrus, post-central gyrus and superior parietal lobule as the children walked on a treadmill. A sagittal plane video was concurrently collected and later digitized to quantify the temporal gait variations.