Neuroprosthetic Technology for Individuals with Spinal Cord Injury
Spinal cord injury (SCI) results in a loss of function and sensation below the level of the lesion. Neuroprosthetic technology has been developed to help restore motor and autonomic functions as well as to provide sensory feedback.
This paper provides an overview of neuroprosthetic technology that aims to address the priorities for functional restoration as defined by individuals with SCI. We describe neuroprostheses that are in various stages of preclinical development, clinical testing, and commercialization including functional electrical stimulators, epidural and intraspinal microstimulation, bladder neuroprosthesis, and cortical stimulation for restoring sensation. We also discuss neural recording technologies that may provide command or feedback signals for neuroprosthetic devices. Conclusion/clinical relevance: Neuroprostheses have begun to address the priorities of individuals with SCI, although there remains room for improvement. In addition to continued technological improvements, closing the loop between the technology and the user may help provide intuitive device control with high levels of performance.
Available from: Dawn M Taylor
- "Users of BCI-controlled devices, such as an upper-limb neuroprosthesis [1-4], must be able to use their device while talking and performing other cognitive tasks. Talking could potentially degrade EEG-controlled BCIs due to power spectral changes associated with verbal and cognitive engagement and the large electrical signals from muscles under the scalp. "
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ABSTRACT: Brain-computer interface (BCI) systems have been developed to provide paralyzed individuals the ability to command the movements of an assistive device using only their brain activity. BCI systems are typically tested in a controlled laboratory environment were the user is focused solely on the brain-control task. However, for practical use in everyday life people must be able to use their brain-controlled device while mentally engaged with the cognitive responsibilities of daily activities and while compensating for any inherent dynamics of the device itself. BCIs that use electroencephalography (EEG) for movement control are often assumed to require significant mental effort, thus preventing users from thinking about anything else while using their BCI. This study tested the impact of cognitive load as well as speaking on the ability to use an EEG-based BCI.
Six participants controlled the two-dimensional (2D) movements of a simulated neuroprosthesis-arm under three different levels of cognitive distraction. The two higher cognitive load conditions also required simultaneously speaking during BCI use. On average, movement performance declined during higher levels of cognitive distraction, but only by a limited amount. Movement completion time increased by 7.2%, the percentage of targets successfully acquired declined by 11%, and path efficiency declined by 8.6%. Only the decline in percentage of targets acquired and path efficiency were statistically significant (p < 0.05).
People who have relatively good movement control of an EEG-based BCI may be able to speak and perform other cognitively engaging activities with only a minor drop in BCI-control performance.
Journal of NeuroEngineering and Rehabilitation 12/2013; 10(1):116. DOI:10.1186/1743-0003-10-116 · 2.74 Impact Factor
Available from: Shubo Chakrabarti
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ABSTRACT: The function of the mammalian motor cortex was one of the first problems studied in neuroscience. But until today, the major principles of the workings of the motor cortex have remained conjectural. It is clear that motor cortex holds a topographic map of body parts. But does that mean that the motor cortex itself is undertaking the challenging task of converting motor plans (i.e., intended trajectories and effects of actions) into low level motor commands appropriate to drive the muscles? Work of many decades on motor function has revealed the existence of dedicated networks, the so-called central pattern generators (CPGs). Many, if not all of these CPGs, are located subcortically and are likely to be involved in the translation of motor plans into actual muscle contractions. Unfortunately the detailed circuitry and cellular elements of CPGs are only vaguely known. More recent work has elucidated continuous as well as discontinuous (discrete) mapping of the motor cortex to movement. For the quest of understanding motor cortex–CPG interactions, discontinuities are important because they allow us to dissect how neighboring motor cortex sites connect to different CPGs for different purposes—but driving the very same muscles. The rodent whisker motor system is a decidedly modular system. Neighboring cortical areas drive very distinct whisker movements used by the animals in different contexts. We argue that the modularity of the whisker system together with its great accessibility is promising to establish a model system for the interactions of the motor cortex and CPGs on the cellular and network levels and, thus, will also be of high value in understanding the more complex and continuously organized motor cortex of the arm/hand/finger system in primates.
03/2014; 5(1):20-27. DOI:10.1007/s13295-014-0051-y
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In spite of extensive research, the progress toward a cure in spinal cord injury (SCI) is still elusive, which holds good for the cell- and stem cell-based therapies. We have critically analyzed seven known gray areas in SCI, indicating the specific arenas for research to improvise the outcome of cell-based therapies in SCI.
The seven, specific known gray areas in SCI analyzed are: i) the gap between animal models and human victims; ii) uncertainty about the time, route and dosage of cells applied; iii) source of the most efficacious cells for therapy; iv) inability to address the vascular compromise during SCI; v) lack of non-invasive methodologies to track the transplanted cells; vi) need for scaffolds to retain the cells at the site of injury; and vii) physical and chemical stimuli that might be required for synapses formation yielding functional neurons.
Further research on scaffolds for retaining the transplanted cells at the lesion, chemical and physical stimuli that may help neurons become functional, a meta-analysis of timing of the cell therapy, mode of application and larger clinical studies are essential to improve the outcome.
Expert opinion on biological therapy 03/2014; 14(5). DOI:10.1517/14712598.2014.889676 · 3.74 Impact Factor
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