Eye gaze correlates of motor impairment in VR observation of motor actions

Introduction: This article is part of the Focus Theme of Methods of Information in Medicine on “Methodologies, Models and A lgorithms for Patients Rehabilitation”. Objective: Identify eye gaze correlates of motor impairment in a virtual reality motor observation task in a study with healthy participants and stroke patients. Methods: Participants consisted of a group of healthy subjects (N = 20) and a group of stroke survivors (N = 10). Both groups were required to observe a simple reach-and-grab and place-and-release task in a virtual environment. Additionally, healthy subjects were required to observe the task in a normal condition and a constrained movement condition. Eye movements were recorded during the observation task for later analysis.info:eu-repo/semantics/publishedVersio

Brain–computer interfacing with interactive systems-Case study 2

info:eu-repo/semantics/publishedVersio

Quantifying cognitive-motor interference in virtual reality training after stroke: the role of interfaces

Globally, stroke is the second leading cause of death above the age of 60 years, with the actual number of strokes to increase because of the ageing population. Stroke results into chronic conditions, loss of independence, affecting both the families of stroke survivors but also public health systems. Virtual Reality (VR) for rehabilitation is considered a novel and effective low-cost approach to re-train motor and cognitive function through strictly defined training tasks in a safe simulated environment. However, little is known about how the choice of VR interfacing technology affects motor and cognitive performance, or what the most cost-effective rehabilitation approach for patients with different prognostics is. In this paper we assessed the effect of four different interfaces in the training of the motor and cognitive domains within a VR neurorehabilitation task. In this study we have evaluated the effect of training using 2-dimensional and 3-dimensional as well as traditional and natural user interfaces with both stroke survivors and healthy participants. Results indicate that 3-dimensional interfaces contribute towards better results in the motor domain at the cost of lower performance in the cognitive domain, suggesting the use 2-dimensional natural user interfaces as a trade-off. Our results provide useful pointers for future directions towards a cost-effective and meaningful interaction in virtual rehabilitation tasks in both motor and cognitive domains.info:eu-repo/semantics/publishedVersio

Finding the optimal time window for increased classification accuracy during motor imagery

Motor imagery classification using electroencephalography is based on feature extraction over a length of time, and different configurations of settings can alter the performance of a classifier. Nevertheless, there is a lack of standardized settings for motor imagery classification. This work analyzes the effect of age on motor imagery training performance for two common spatial pattern-based classifier pipelines and various configurations of timing parameters, such as epochs, windows, and offsets. Results showed significant (p ≤ 0.01) inverse correlations between performance and feature quantity, as well as between performance and epoch/window ratio.info:eu-repo/semantics/publishedVersio

Impact of age, VR, immersion, and spatial resolution on classifier performance for a MI-based BCI

There are many factors outlined in the signal processing pipeline that impact brain–computer interface (BCI) performance, but some methodological factors do not depend on signal processing. Nevertheless, there is a lack of research assessing the effect of such factors. Here, we investigate the impact of VR, immersiveness, age, and spatial resolution on the classifier performance of a Motor Imagery (MI) electroencephalography (EEG)-based BCI in naïve participants. We found significantly better performance for VR compared to non-VR (15 electrodes: VR 77.48 ± 6.09%, non-VR 73.5 ± 5.89%, p = 0.0096; 12 electrodes: VR 73.26 ± 5.2%, non-VR 70.87 ± 4.96%, p = 0.0129; 7 electrodes: VR 66.74 ± 5.92%, non-VR 63.09 ± 8.16%, p = 0.0362) and better performance for higher electrode quantity, but no significant differences were found between immersive and non immersive VR. Finally, there was not a statistically significant correlation found between age and classifier performance, but there was a direct relation found between spatial resolution (electrode quantity) and classifier performance (r = 1, p = 0.0129, VR; r = 0.99, p = 0.0859, non-VR).info:eu-repo/semantics/publishedVersio

An integrative virtual reality cognitive-motor intervention approach in stroke rehabilitation: a pilot study

Stroke is one of the most common causes of acquired disability, leaving numerous adults with cognitive and motor impairments, and affecting patient’s capability to live independently. In post-stroke it is imperative to initiate a process of intensive rehabilitation and personalized objectives to maximize functional cognitive and motor recovery. Virtual Reality (VR) technology is being widely applied to rehabilitation of stroke, however, not in an integrative manner. Like traditional rehabilitation, these new tools mostly focus either in the cognitive or in the motor domain, which can take to a reduced impact in the performance of activities of daily living, most of them dual-task. Assuming the existence of cognitive and motor recovery interdependence, RehabNet proposes a holistic approach. Here we present a one-month long pilot study with three stroke patients whose training was a game-like VR version of the Toulouse-Piéron cancellation test, adapted to be performed by repetitive arm reaching movements. A standardized motor and cognitive assessment was performed pre and post intervention. The first results on this intervention support a holistic model for rehabilitation of stroke patients, sustaining interdependence on cognitive and motor recovery. Furthermore, we observed that the impact of the integrative VR approach generalizes to the performance of the activities of daily living.info:eu-repo/semantics/publishedVersio

Performance of an inverted sputter source

An inverted sputter source manufactured locally was installed on the Demokritos Tandem for heavy ion production. The source is utilizing as an extracted beam the negative ions that are found to be back streaming towards the ionizer in a regular sputter source. The source produces in sufficient quantities a number of ion species with rather few signs of ionizer erosion. Concerning the quality of the beam, direct comparison of the transmission through the accelerator of an oxygen beam produced by the sputter source and a diode source indicates the same percentage of transmission.Pour la production d'ions lourds, nous avons construit et installé sur l'accélérateur TANDEM de NRC Demokritos, une source sputtering renversée. Avec cette source les ions négatifs qui, dans les sources sputtering normales, vont vers l'ioniseur sont utilisés comme faisceau. La source produit un nombre d'ions lourds en quantité suffisante sans érosion significative de l'ioniseur. Pour comparer la qualité du faisceau, on a transmit un faisceau d'oxygène produit par la source renversée et la source diode. Le même pourcentage de transmission à travers l'accélérateur a été observé, indiquant une qualité de faisceau similaire pour les deux sources

Performance of an inverted sputter source

An inverted sputter source manufactured locally was installed on the Demokritos Tandem for heavy ion production. The source is utilizing as an extracted beam the negative ions that are found to be back streaming towards the ionizer in a regular sputter source. The source produces in sufficient quantities a number of ion species with rather few signs of ionizer erosion. Concerning the quality of the beam, direct comparison of the transmission through the accelerator of an oxygen beam produced by the sputter source and a diode source indicates the same percentage of transmission