Hochberg, L. R. et al. Neuronal ensemble control of prosthetic devices by a human with tetraplegia. Nature 442, 164-171

Department of Neurology, Massachusetts General Hospital, Brigham and Women's Hospital, and Spaulding Rehabilitation Hospital, Harvard Medical School, 55 Fruit Street, Boston, Massachusetts 02114, USA.
Nature (Impact Factor: 41.46). 08/2006; 442(7099):164-71. DOI: 10.1038/nature04970
Source: PubMed


Neuromotor prostheses (NMPs) aim to replace or restore lost motor functions in paralysed humans by routeing movement-related signals from the brain, around damaged parts of the nervous system, to external effectors. To translate preclinical results from intact animals to a clinically useful NMP, movement signals must persist in cortex after spinal cord injury and be engaged by movement intent when sensory inputs and limb movement are long absent. Furthermore, NMPs would require that intention-driven neuronal activity be converted into a control signal that enables useful tasks. Here we show initial results for a tetraplegic human (MN) using a pilot NMP. Neuronal ensemble activity recorded through a 96-microelectrode array implanted in primary motor cortex demonstrated that intended hand motion modulates cortical spiking patterns three years after spinal cord injury. Decoders were created, providing a 'neural cursor' with which MN opened simulated e-mail and operated devices such as a television, even while conversing. Furthermore, MN used neural control to open and close a prosthetic hand, and perform rudimentary actions with a multi-jointed robotic arm. These early results suggest that NMPs based upon intracortical neuronal ensemble spiking activity could provide a valuable new neurotechnology to restore independence for humans with paralysis.

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    • "The first strategy aims at bypassing nonfunctional cortico-spinal pathways to allow for continuous and permanent control of robotic devices (Collinger et al., 2013) or functional electric stimulation (FES) of paralyzed muscles (Moritz et al., 2008; Pohlmeyer et al., 2009; Ethier et al., 2012; McGie et al., in press; Pfurtscheller et al., 2003). By substituting for lost motor functions, such assistive BMIs have demonstrated recovery of versatile motor control in daily life activities (Hochberg et al., 2006; Collinger et al., 2013). The second strategy aims at facilitation of neuroplasticity and motor learning to enhance motor recovery (rehabilitative BMIs) (Dobkin, 2007; Soekadar et al., 2011a) (Fig. 1a). "

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    • "These devices act by creating a direct mapping between recorded neural activity and the movement of an external actuator, like a computer cursor or a robotic arm (Fig. 1) (Chapin 2004; Serruya et al. 2002; Taylor et al. 2002; Carmena et al. 2003; Musallam et al. 2004). Early clinical trials with intracortical BMIs, which use as their control signal the recorded activity of populations of single neurons, have recently shown that paralyzed individuals can effectively control computer cursors (Hochberg et al. 2006) and robotic arms of varying complexity (Hochberg et al. 2012; Collinger et al. 2013; Aflalo et al. 2015). However, much work yet needs to be done to give subjects control over artificial limbs that might rival control of the natural limb (Gilja et al. 2012). "
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    ABSTRACT: With the goal of improving the quality of life for people suffering from various motor control disorders, brain-machine interfaces provide direct neural control of prosthetic devices by translating neural signals into control signals. These systems act by reading motor intent signals directly from the brain and using them to control, for example, the movement of a cursor on a computer screen. Over the past two decades, much attention has been devoted to the decoding problem: how should recorded neural activity be translated into the movement of the cursor? Most approaches have focused on this problem from an estimation standpoint, i.e., decoders are designed to return the best estimate of motor intent possible, under various sets of assumptions about how the recorded neural signals represent motor intent. Here we recast the decoder design problem from a physical control system perspective, and investigate how various classes of decoders lead to different types of physical systems for the subject to control. This framework leads to new interpretations of why certain types of decoders have been shown to perform better than others. These results have implications for understanding how motor neurons are recruited to perform various tasks, and may lend insight into the brain’s ability to conceptualize artificial systems.
    Journal of Computational Neuroscience 07/2015; 39(2):1-12. DOI:10.1007/s10827-015-0566-4 · 1.74 Impact Factor
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    • "Thanks to technological progress based on non-invasive EEG and invasive intracortical recording (Hochberg et al., 2006; Aflalo et al., 2015), people may be capable of using brain activity to control BCI devices (Birbaumer et al., 1999) and to move a prosthetic or robotic limb. Most of the current BCI systems are based on at least two main cognitive and brain processes. "
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    ABSTRACT: Acting efficiently in the world depends on the activity of motor and somatosensory systems, the integration of which is necessary for the proper functioning of the sensorimotor loop (SL). Profound alterations of SL functioning follow spinal cord injury (SCI), a condition that brings about a disconnection of the body from the brain. Such disconnection creates a substantial deprivation of somatosensorial inputs and motor outputs. Consequent somatic deficits and motor paralysis affect the body below the lesion level. A complete restoration of normal functions of the SL cannot be expected until basic neuroscience has found a way to re-establish the interrupted neural connectivity. Meanwhile, studies should focus on the development of technical solutions for dealing with the disruption of the sensorimotor loop. This review discusses the structural and functional adaptive reorganization of the brain after SCI, and the maladaptive mechanisms that impact on the processing of body related information, which alter motor imagery strategies and EEG signals. Studies that show how residual functions (e.g. face tactile sensitivity) may help people to restore a normal body image are also reviewed. Finally, data on how brain and residual body signals may be used to improve brain computer interface systems is discussed in relation to the issue of how such systems may help SCI people to re-enter the world and interact with objects and other individuals.
    Neuropsychologia 06/2015; · 3.30 Impact Factor
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