title: Coupling brain-machine interfaces with cortical stimulation for brain-state dependent stimulation: enhancing motor cortex excitability for neurorehabilitation.
abstract: Motor recovery after stroke is an unsolved challenge despite intensive rehabilitation training programs. Brain stimulation techniques have been explored in addition to traditional rehabilitation training to increase the excitability of the stimulated motor cortex. This modulation of cortical excitability augments the response to afferent input during motor exercises, thereby enhancing skilled motor learning by long-term potentiation-like plasticity. Recent approaches examined brain stimulation applied concurrently with voluntary movements to induce more specific use-dependent neural plasticity during motor training for neurorehabilitation. Unfortunately, such approaches are not applicable for the many severely affected stroke patients lacking residual hand function. These patients require novel activity-dependent stimulation paradigms based on intrinsic brain activity. Here, we report on such brain state-dependent stimulation (BSDS) combined with haptic feedback provided by a robotic hand orthosis. Transcranial magnetic stimulation (TMS) of the motor cortex and haptic feedback to the hand were controlled by sensorimotor desynchronization during motor-imagery and applied within a brain-machine interface (BMI) environment in one healthy subject and one patient with severe hand paresis in the chronic phase after stroke. BSDS significantly increased the excitability of the stimulated motor cortex in both healthy and post-stroke conditions, an effect not observed in non-BSDS protocols. This feasibility study suggests that closing the loop between intrinsic brain state, cortical stimulation and haptic feedback provides a novel neurorehabilitation strategy for stroke patients lacking residual hand function, a proposal that warrants further investigation in a larger cohort of stroke patients.
authors.affiliation: Division of Functional and Restorative Neurosurgery, Division of Translational Neurosurgery, Department of Neurosurgery, Eberhard Karls University Tuebingen Tuebingen, Germany ; Neuroprosthetics Research Group, Department of Integrative Neuroscience, Werner Reichardt Centre, Eberhard Karls University Tübingen, Germany.
authors.forename: Alireza
authors.initials: A
authors.lastname: Gharabaghi
authors.affiliation: Division of Functional and Restorative Neurosurgery, Division of Translational Neurosurgery, Department of Neurosurgery, Eberhard Karls University Tuebingen Tuebingen, Germany ; Neuroprosthetics Research Group, Department of Integrative Neuroscience, Werner Reichardt Centre, Eberhard Karls University Tübingen, Germany.
authors.forename: Dominic
authors.initials: D
authors.lastname: Kraus
authors.affiliation: Division of Functional and Restorative Neurosurgery, Division of Translational Neurosurgery, Department of Neurosurgery, Eberhard Karls University Tuebingen Tuebingen, Germany ; Neuroprosthetics Research Group, Department of Integrative Neuroscience, Werner Reichardt Centre, Eberhard Karls University Tübingen, Germany.
authors.forename: Maria T
authors.initials: MT
authors.lastname: Leão
authors.affiliation: Department of Computer Engineering, Wilhelm-Schickard Institute for Computer Science, Eberhard Karls University Tuebingen Tuebingen, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Spüler
authors.affiliation: Department of Computer Engineering, Wilhelm-Schickard Institute for Computer Science, Eberhard Karls University Tuebingen Tuebingen, Germany.
authors.forename: Armin
authors.initials: A
authors.lastname: Walter
authors.affiliation: Department of Computer Engineering, Wilhelm-Schickard Institute for Computer Science, Eberhard Karls University Tuebingen Tuebingen, Germany ; Department of Computer Engineering, University of Leipzig Leipzig, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Bogdan
authors.affiliation: Department of Computer Engineering, Wilhelm-Schickard Institute for Computer Science, Eberhard Karls University Tuebingen Tuebingen, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Rosenstiel
authors.affiliation: Division of Functional and Restorative Neurosurgery, Division of Translational Neurosurgery, Department of Neurosurgery, Eberhard Karls University Tuebingen Tuebingen, Germany ; Neuroprosthetics Research Group, Department of Integrative Neuroscience, Werner Reichardt Centre, Eberhard Karls University Tübingen, Germany.
authors.forename: Georgios
authors.initials: G
authors.lastname: Naros
authors.affiliation: Department of Neurology and Stroke, Hertie Institute for Clinical Brain Research, Eberhard Karls University Tuebingen Tuebingen, Germany.
authors.forename: Ulf
authors.initials: U
authors.lastname: Ziemann
keywords: activity-dependent stimulation; brain state-dependent stimulation; brain-computer interface; brain-machine interface; brain-robot interface; closed-loop stimulation; neurorehabilitation; transcranial magnetic stimulation