title: Real-time closed-loop control of cognitive load in neurological patients during robot-assisted gait training.
abstract: Cognitively challenging training sessions during robot-assisted gait training after stroke were shown to be key requirements for the success of rehabilitation. Despite a broad variability of cognitive impairments amongst the stroke population, current rehabilitation environments do not adapt to the cognitive capabilities of the patient, as cognitive load cannot be objectively assessed in real-time. We provided healthy subjects and stroke patients with a virtual task during robot-assisted gait training, which allowed modulating cognitive load by adapting the difficulty level of the task. We quantified the cognitive load of stroke patients by using psychophysiological measurements and performance data. In open-loop experiments with healthy subjects and stroke patients, we obtained training data for a linear, adaptive classifier that estimated the current cognitive load of patients in real-time. We verified our classification results via questionnaires and obtained 88% correct classification in healthy subjects and 75% in patients. Using the pre-trained, adaptive classifier, we closed the cognitive control loop around healthy subjects and stroke patients by automatically adapting the difficulty level of the virtual task in real-time such that patients were neither cognitively overloaded nor under-challenged.
authors.affiliation: Sensory-Motor Systems Lab, Department of Mechanical Engineering and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland. koenig@mavt.ethz.ch
authors.forename: Alexander
authors.initials: A
authors.lastname: Koenig
authors.forename: Domen
authors.initials: D
authors.lastname: Novak
authors.forename: Ximena
authors.initials: X
authors.lastname: Omlin
authors.forename: Michael
authors.initials: M
authors.lastname: Pulfer
authors.forename: Eric
authors.initials: E
authors.lastname: Perreault
authors.forename: Lukas
authors.initials: L
authors.lastname: Zimmerli
authors.forename: Matjaz
authors.initials: M
authors.lastname: Mihelj
authors.forename: Robert
authors.initials: R
authors.lastname: Riener
mesh_terms: D000223:Adaptation, Psychological / Q000502:physiology; D000328:Adult; D000368:Aged; D000465:Algorithms; D003071:Cognition / Q000502:physiology*; D003199:Computer Systems; D003201:Computers; D016208:Databases, Factual; D005081:Exercise Therapy / Q000379:methods; D005260:Female; D005684:Gait / Q000502:physiology*; D020233:Gait Disorders, Neurologic / Q000503:physiopathology / Q000534:rehabilitation*; D005712:Galvanic Skin Response / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D005082:Physical Exertion; D011597:Psychomotor Performance / Q000502:physiology; D056152:Respiratory Rate / Q000502:physiology; D012371:Robotics; D012881:Skin Temperature / Q000502:physiology; D000071939:Stroke Rehabilitation; D011795:Surveys and Questionnaires; D014584:User-Computer Interface; D016138:Walking / Q000502:physiology