Staff member

Martina Maier

PhD Student
Synthetic, Perceptive, Emotive and Cognitive Systems (SPECS)

Staff member publications

Maier, Martina, Rubio Ballester, Belén, Duff, Armin, Duarte Oller, Esther, Verschure, P., (2019). Effect of specific over nonspecific VR-based rehabilitation on poststroke motor recovery: A systematic meta-analysis Neurorehabilitation and Neural Repair On-line,

Background. Despite the rise of virtual reality (VR)-based interventions in stroke rehabilitation over the past decade, no consensus has been reached on its efficacy. This ostensibly puzzling outcome might not be that surprising given that VR is intrinsically neutral to its use—that is, an intervention is effective because of its ability to mobilize recovery mechanisms, not its technology. As VR systems specifically built for rehabilitation might capitalize better on the advantages of technology to implement neuroscientifically grounded protocols, they might be more effective than those designed for recreational gaming. Objective. We evaluate the efficacy of specific VR (SVR) and nonspecific VR (NSVR) systems for rehabilitating upper-limb function and activity after stroke. Methods. We conducted a systematic search for randomized controlled trials with adult stroke patients to analyze the effect of SVR or NSVR systems versus conventional therapy (CT). Results. We identified 30 studies including 1473 patients. SVR showed a significant impact on body function (standardized mean difference [SMD] = 0.23; 95% CI = 0.10 to 0.36; P = .0007) versus CT, whereas NSVR did not (SMD = 0.16; 95% CI = −0.14 to 0.47; P = .30). This result was replicated in activity measures. Conclusions. Our results suggest that SVR systems are more beneficial than CT for upper-limb recovery, whereas NSVR systems are not. Additionally, we identified 6 principles of neurorehabilitation that are shared across SVR systems and are possibly responsible for their positive effect. These findings may disambiguate the contradictory results found in the current literature.

Keywords: Stroke, Paresis, Virtual reality, Rehabilitation, Occupational therapy, Review

Rubio Ballester, Belen, Duff, Armin, Maier, Martina, Cameirao, Monica, Bermudez, Sergi, Duarte, Esther, Cuxart, Ampar, Rodriguez, Susana, Verschure, Paul F. M. J., (2019). Revealing an extended critical window of recovery post-stroke bioRxiv (pre-print server) , 458745

The impact of rehabilitation on post-stroke motor recovery and its dependency on the patient's chronicity remain unclear. The existence and regularity of a, so called, proportional recovery rule across a range of functional deficits and therapies supports the notion that functional interventions have little or no impact beyond spontaneous recovery rates in a 'critical window of recovery' which lasts from 3 to 6 months post-stroke. In this meta-analysis, we apply a bootstrap analysis method to assess the overall impact of a specific VR-based rehabilitation protocol for the upper extremities on a homogeneous sample of 219 individuals with hemiparesis at various stages post stroke. Our analysis uncovers a precise gradient of sensitivity to treatment that expands more than one year beyond the limits of the so-called 'critical window of recovery'. These findings redefine the limits of the so-called 'critical window of recovery' and suggest that stroke-derived plasticity mechanisms do facilitate functional recovery even at the chronic and late chronic stage.

Maier, M., Low, S. C., Ballester, B. R., Bañuelos, N. L., Oller, E. D., Verschure, P., (2018). Depression modulates attentional processing after stroke Converging Clinical and Engineering Research on Neurorehabilitation III (Biosystems and Biorobotics) 4th International Conference on NeuroRehabilitation (ICNR2018) , Springer, Cham (Pisa, Italy) 21, 702-706

Depression is a common sequela after stroke and has severe implications on a patient’s life. Post-stroke depression has been linked to cognitive impairment, but the mechanisms that lead to this deficit are not well understood. We tested 18 chronic stroke patients with depression in a psychophysical task to evaluate their attentional processing under varying cognitive loads. We found that the level of depression had no effect on the unconscious, bottom-up components of attentional processing but did influence the top-down ones. These results support the notion that depression might act like an additional cognitive load, impeding the conscious processes and responses although the information has been unconsciously processed.

We demonstrate simultaneous transverse dynamic force microscopy and molecular recognition imaging using tuning forks as piezoelectric sensors. Tapered aluminum-coated glass fibers were chemically functionalized with biotin and anti-lysozyme molecules and attached to one of the prongs of a 32 kHz tuning fork. The lateral oscillation amplitude of the tuning fork was used as feedback signal for topographical imaging of avidin aggregates and lysozyme molecules on mica substrate. The phase difference between the excitation and detection signals of the tuning fork provided molecular recognition between avidin/biotin or lysozyme/anti-lysozyme. Aggregates of avidin and lysozyme molecules appeared as features with heights of 1-4 nm in the topographic images, consistent with single molecule atomic force microscopy imaging. Recognition events between avidin/biotin or lysozyme/anti-lysozyme were detected in the phase image at high signal-to-noise ratio with phase shifts of 1-2 degrees. Because tapered glass fibers and shear-force microscopy based on tuning forks are commonly used for near-field scanning optical microscopy (NSOM), these results open the door to the exciting possibility of combining optical, topographic and biochemical recognition at the nanometer scale in a single measurement and in liquid conditions.

Keywords: Tuning fork, Atomic force microscopy, Shear-force microscopy, Molecular recognition, Avidin-biotin