Parkinson\u27s Patients\u27 Upper and Lower Limb Motor Impairments Differentially Influence Action Verb Processing

Theories of grounded cognition emphasize the role of sensorimotor simulation in conceptual knowledge. With regard to action concepts, the motor system is hypothesized to play a central role in their representation and processing. The present study investigates whether patients with Parkinson’s disease (PD) who have greater upper versus greater lower limb impairments show different patterns of performance when processing action verbs. Patients and matched controls made action decisions on upper-limb (reach), lower-limb (kick), and psych verbs (think). The most important result was an interaction between PD dominance (PD upper vs. lower limb motor impairments) and verb type (upper- vs. lower-limb verbs). PD patients with greater upper limb impairment were slower in processing upper-limb versus lower-limb verbs, whereas those with greater lower limb impairment performed similarly on these verb types. The results support a relatively fine-grained functional role of the motor system in the conceptual representation of action verbs

Design and Development of an Affordable Haptic Robot with Force-Feedback and Compliant Actuation to Improve Therapy for Patients with Severe Hemiparesis

The study describes the design and development of a single degree-of-freedom haptic robot, Haptic Theradrive, for post-stroke arm rehabilitation for in-home and clinical use. The robot overcomes many of the weaknesses of its predecessor, the TheraDrive system, that used a Logitech steering wheel as the haptic interface for rehabilitation. Although the original TheraDrive system showed success in a pilot study, its wheel was not able to withstand the rigors of use. A new haptic robot was developed that functions as a drop-in replacement for the Logitech wheel. The new robot can apply larger forces in interacting with the patient, thereby extending the functionality of the system to accommodate low-functioning patients. A new software suite offers appreciably more options for tailored and tuned rehabilitation therapies. In addition to describing the design of the hardware and software, the paper presents the results of simulation and experimental case studies examining the system\u27s performance and usability

Inter-Joint Coordination Deficits Revealed in the Decomposition of Endpoint Jerk During Goal-Directed Arm Movement After Stroke

It is well documented that neurological deficits after stroke can disrupt motor control processes that affect the smoothness of reaching movements. The smoothness of hand trajectories during multi-joint reaching depends on shoulder and elbow joint angular velocities and their successive derivatives as well as on the instantaneous arm configuration and its rate of change. Right-handed survivors of unilateral hemiparetic stroke and neurologically-intact control participants held the handle of a two-joint robot and made horizontal planar reaching movements. We decomposed endpoint jerk into components related to shoulder and elbow joint angular velocity, acceleration, and jerk. We observed an abnormal decomposition pattern in the most severely impaired stroke survivors consistent with deficits of inter-joint coordination. We then used numerical simulations of reaching movements to test whether the specific pattern of inter-joint coordination deficits observed experimentally could be explained by either a general increase in motor noise related to weakness or by an impaired ability to compensate for multi-joint interaction torque. Simulation results suggest that observed deficits in movement smoothness after stroke more likely reflect an impaired ability to compensate for multi-joint interaction torques rather than the mere presence of elevated motor noise

Designing for designers: Towards the development of accessible ICT products and services using the VERITAS framework

Among key design practices which contribute to the development of inclusive ICT products and services is user testing with people with disabilities. Traditionally, this involves partial or minimal user testing through the usage of standard heuristics, employing external assisting devices, and the direct feedback of impaired users. However, efficiency could be improved if designers could readily analyse the needs of their target audience. The VERITAS framework simulates and systematically analyses how users with various impairments interact with the use of ICT products and services. Findings show that the VERITAS framework is useful to designers, offering an intuitive approach to inclusive design.The work presented in this article forms part of VERITAS, which is funded by the European Commission's 7th Framework Programme (FP7) (grant agreement # 247765 FP7-ICT-2009.7.2)

First report of generalized face processing difficulties in möbius sequence.

Reverse simulation models of facial expression recognition suggest that we recognize the emotions of others by running implicit motor programmes responsible for the production of that expression. Previous work has tested this theory by examining facial expression recognition in participants with Möbius sequence, a condition characterized by congenital bilateral facial paralysis. However, a mixed pattern of findings has emerged, and it has not yet been tested whether these individuals can imagine facial expressions, a process also hypothesized to be underpinned by proprioceptive feedback from the face. We investigated this issue by examining expression recognition and imagery in six participants with Möbius sequence, and also carried out tests assessing facial identity and object recognition, as well as basic visual processing. While five of the six participants presented with expression recognition impairments, only one was impaired at the imagery of facial expressions. Further, five participants presented with other difficulties in the recognition of facial identity or objects, or in lower-level visual processing. We discuss the implications of our findings for the reverse simulation model, and suggest that facial identity recognition impairments may be more severe in the condition than has previously been noted

Multiscale Topological Properties Of Functional Brain Networks During Motor Imagery After Stroke

In recent years, network analyses have been used to evaluate brain reorganization following stroke. However, many studies have often focused on single topological scales, leading to an incomplete model of how focal brain lesions affect multiple network properties simultaneously and how changes on smaller scales influence those on larger scales. In an EEG-based experiment on the performance of hand motor imagery (MI) in 20 patients with unilateral stroke, we observed that the anatomic lesion affects the functional brain network on multiple levels. In the beta (13-30 Hz) frequency band, the MI of the affected hand (Ahand) elicited a significantly lower smallworldness and local efficiency (Eloc) versus the unaffected hand (Uhand). Notably, the abnormal reduction in Eloc significantly depended on the increase in interhemispheric connectivity, which was in turn determined primarily by the rise in regional connectivity in the parieto-occipital sites of the affected hemisphere. Further, in contrast to the Uhand MI, in which significantly high connectivity was observed for the contralateral sensorimotor regions of the unaffected hemisphere, the regions that increased in connection during the Ahand MI lay in the frontal and parietal regions of the contralaterally affected hemisphere. Finally, the overall sensorimotor function of our patients, as measured by Fugl-Meyer Assessment (FMA) index, was significantly predicted by the connectivity of their affected hemisphere. These results increase our understanding of stroke-induced alterations in functional brain networks.Comment: Neuroimage, accepted manuscript (unedited version) available online 19-June-201

Onset of Mild Cognitive Impairment in Parkinson Disease

Objective: Characterize the onset and timing of cognitive decline in Parkinson disease (PD) from the first recognizable stage of cognitively symptomatic PD-mild cognitive impairment (PD-MCI) to PD dementia (PDD). Thirty-nine participants progressed from PD to PDD and 25 remained cognitively normal. Methods: Bayesian-estimated disease-state models described the onset of an individual’s cognitive decline across 12 subtests with a change point. Results: Subtests measuring working memory, visuospatial processing ability, and crystalized memory changed significantly 3 to 5 years before their first nonzero Clinical Dementia Rating and progressively worsened from PD to PD-MCI to PDD. Crystalized memory deficits were the hallmark feature of imminent conversion of cognitive status. Episodic memory tasks were not sensitive to onset of PD-MCI. For cognitively intact PD, all 12 subtests showed modest linear decline without evidence of a change point. Conclusions: Longitudinal disease-state models support a prodromal dementia stage (PD-MCI) marked by early declines in working memory and visuospatial processing beginning 5 years before clinical diagnosis of PDD. Cognitive declines in PD affect motor ability (bradykinesia), working memory, and processing speed (bradyphrenia) resulting in PD-MCI where visuospatial imagery and memory retrieval deficits manifest before eventual development of overt dementia. Tests of episodic memory may not be sufficient to detect and quantify cognitive decline in PD

Embodying functionally relevant action sounds in patients with spinal cord injury

Growing evidence indicates that perceptual-motor codes may be associated with and influenced by actual bodily states. Following a spinal cord injury (SCI), for example, individuals exhibit reduced visual sensitivity to biological motion. However, a dearth of direct evidence exists about whether profound alterations in sensorimotor traffic between the body and brain influence audio-motor representations. We tested 20 wheelchair-bound individuals with lower skeletal-level SCI who were unable to feel and move their lower limbs, but have retained upper limb function. In a two-choice, matching-to-sample auditory discrimination task, the participants were asked to determine which of two action sounds matched a sample action sound presented previously. We tested aural discrimination ability using sounds that arose from wheelchair, upper limb, lower limb, and animal actions. Our results indicate that an inability to move the lower limbs did not lead to impairment in the discrimination of lower limb-related action sounds in SCI patients. Importantly, patients with SCI discriminated wheelchair sounds more quickly than individuals with comparable auditory experience (i.e. physical therapists) and inexperienced, able-bodied subjects. Audio-motor associations appear to be modified and enhanced to incorporate external salient tools that now represent extensions of their body schema

Articulating: the neural mechanisms of speech production

Speech production is a highly complex sensorimotor task involving tightly coordinated processing across large expanses of the cerebral cortex. Historically, the study of the neural underpinnings of speech suffered from the lack of an animal model. The development of non-invasive structural and functional neuroimaging techniques in the late 20th century has dramatically improved our understanding of the speech network. Techniques for measuring regional cerebral blood flow have illuminated the neural regions involved in various aspects of speech, including feedforward and feedback control mechanisms. In parallel, we have designed, experimentally tested, and refined a neural network model detailing the neural computations performed by specific neuroanatomical regions during speech. Computer simulations of the model account for a wide range of experimental findings, including data on articulatory kinematics and brain activity during normal and perturbed speech. Furthermore, the model is being used to investigate a wide range of communication disorders.R01 DC002852 - NIDCD NIH HHS; R01 DC007683 - NIDCD NIH HHS; R01 DC016270 - NIDCD NIH HHSAccepted manuscrip