Eleonora Guanziroli

Re-thinking the role of motor cortex: Context-sensitive motor outputs?

The standard account of motor control considers descending outputs from primary motor cortex (M1) as motor commands and efference copy. This account has been challenged recently by an alternative formulation in terms of active inference: M1 is considered as part of a sensorimotor hierarchy providing top–down proprioceptive predictions. The key difference between these accounts is that predictions are sensitive to the current proprioceptive context, whereas efference copy is not. Using functional electric stimulation to experimentally manipulate proprioception during voluntary movement in healthy human subjects, we assessed the evidence for context sensitive output from M1. Dynamic causal modeling of functional magnetic resonance imaging responses showed that FES altered proprioception increased the influence of M1 on primary somatosensory cortex (S1). These results disambiguate competing accounts of motor control, provide some insight into the synaptic mechanisms of sensory attenuation and may speak to potential mechanisms of action of FES in promoting motor learning in neurorehabilitation.

A biofeedback cycling training to improve locomotion: a case series study based on gait pattern classification of 153 chronic stroke patients.

BackgroundThe restoration of walking ability is the main goal of post-stroke lower limb rehabilitation and different studies suggest that pedaling may have a positive effect on locomotion. The aim of this study was to explore the feasibility of a biofeedback pedaling treatment and its effects on cycling and walking ability in chronic stroke patients. A case series study was designed and participants were recruited based on a gait pattern classification of a population of 153 chronic stroke patients.MethodsIn order to optimize participants selection, a k-means cluster analysis was performed to subgroup homogenous gait patterns in terms of gait speed and symmetry.The training consisted of a 2-week treatment of 6 sessions. A visual biofeedback helped the subjects in maintaining a symmetrical contribution of the two legs during pedaling. Participants were assessed before, after training and at follow-up visits (one week after treatment). Outcome measures were the unbalance during a pedaling test, and the temporal, spatial, and symmetry parameters during gait analysis.Results and discussionThree clusters, mainly differing in terms of gait speed, were identified and participants, representative of each cluster, were selected.An intra-subject statistical analysis (ANOVA) showed that all patients significantly decreased the pedaling unbalance after treatment and maintained significant improvements with respect to baseline at follow-up. The 2-week treatment induced some modifications in the gait pattern of two patients: one, the most impaired, significantly improved mean velocity and increased gait symmetry; the other one reduced significantly the over-compensation of the healthy limb. No benefits were produced in the gait of the last subject who maintained her slow but almost symmetrical pattern. Thus, this study might suggest that the treatment can be beneficial for patients having a very asymmetrical and inefficient gait and for those that overuse the healthy leg.ConclusionThe results demonstrated that the treatment is feasible and it might be effective in translating progresses from pedaling to locomotion. If these results are confirmed on a larger and controlled scale, the intervention, thanks to its safety and low price, could have a significant impact as a home- rehabilitation treatment for chronic stroke patients.

Normative Data for an Instrumental Assessment of the Upper-Limb Functionality

Upper-limb movement analysis is important to monitor objectively rehabilitation interventions, contributing to improving the overall treatments outcomes. Simple, fast, easy-to-use, and applicable methods are required to allow routinely functional evaluation of patients with different pathologies and clinical conditions. This paper describes the Reaching and Hand-to-Mouth Evaluation Method, a fast procedure to assess the upper-limb motor control and functional ability, providing a set of normative data from 42 healthy subjects of different ages, evaluated for both the dominant and the nondominant limb motor performance. Sixteen of them were reevaluated after two weeks to perform test-retest reliability analysis. Data were clustered into three subgroups of different ages to test the method sensitivity to motor control differences. Experimental data show notable test-retest reliability in all tasks. Data from older and younger subjects show significant differences in the measures related to the ability for coordination thus showing the high sensitivity of the method to motor control differences. The presented method, provided with control data from healthy subjects, appears to be a suitable and reliable tool for the upper-limb functional assessment in the clinical environment.

The Neural Correlates of Long-Term Carryover following Functional Electrical Stimulation for Stroke

Neurorehabilitation effective delivery for stroke is likely to be improved by establishing a mechanistic understanding of how to enhance adaptive plasticity. Functional electrical stimulation is effective at reducing poststroke foot drop; in some patients, the effect persists after therapy has finished with an unknown mechanism. We used fMRI to examine neural correlates of functional electrical stimulation key elements, volitional intent to move and concurrent stimulation, in a group of chronic stroke patients receiving functional electrical stimulation for foot-drop correction. Patients exhibited task-related activation in a complex network, sharing bilateral sensorimotor and supplementary motor activation with age-matched controls. We observed consistent separation of patients with and without carryover effect on the basis of brain responses. Patients who experienced the carryover effect had responses in supplementary motor area that correspond to healthy controls; the interaction between experimental factors in contralateral angular gyrus was seen only in those without carryover. We suggest that the functional electrical stimulation carryover mechanism of action is based on movement prediction and sense of agency/body ownership—the ability of a patient to plan the movement and to perceive the stimulation as a part of his/her own control loop is important for carryover effect to take place.

Validation of a Quantitative Single-Subject Based Evaluation for Rehabilitation-Induced Improvement Assessment

The foreseen outcome of a rehabilitation treatment is a stable improvement on the functional outcomes, which can be longitudinally assessed through multiple measures to help clinicians in functional evaluation. In this study, we propose an automatic comprehensive method of combining multiple measures in order to assess a functional improvement. As test-bed, a functional electrical stimulation based treatment for foot drop correction performed with chronic post-stroke participants is presented. Patients were assessed on five relevant outcome measures before, after intervention, and at a follow-up time-point. A novel algorithm based on variables minimum detectable change is proposed and implemented in a custom-made software, combining the outcome measures to obtain a unique parameter: capacity score. The difference between capacity scores at different timing is thresholded to obtain improvement evaluation. Ten clinicians evaluated patients on the Improvement Clinical Global Impression scale. Eleven patients underwent the treatment, and five resulted to achieve a stable functional improvement, as assessed by the proposed algorithm. A statistically significant agreement between intra-clinicians and algorithm-clinicians evaluations was demonstrated. The proposed method evaluates functional improvement on a single-subject yes/no base by merging different measures (e.g., kinematic, muscular) and it is validated against clinical evaluation.

EMG-Controlled Robotic Hand Rehabilitation Device for Domestic Training

The objective of the present study was to design and experiment a hand rehabilitation device for domestic intensive and repetitive training for subjects affected by hemiparesis, assuring their active participation during the exercise. The designed system is composed by the Gloreha hand rehabilitation glove along with its controller PC, and a device for electromyographic signals recording. To assure user’s volitional involvement during the rehabilitation session, residual volitional EMG is used to trigger the onset of a predetermined hand movement sequence applied in an open-loop modality. In particular, a target hand movement for the rehabilitation session is defined (i.e., grasping, pitching, etc.), and the patient is required to start the movement. Only when the muscular activity overcomes a predefined threshold, Gloreha supports the patient-initiated movement. The designed controller has been tested on a group of healthy volunteers, and on three neurological patients, with different residual ability. All the users were able to calibrate and correctly use the system, and they reported that the system was more challenging to be used with respect to the standard Gloreha-based rehabilitation session, and required more attention and involvement. The results obtained during the preliminary tests are encouraging, and demonstrate the feasibility of the proposed approach.

Can passive mobilization provide clinically-relevant brain stimulation? A pilot eeg and nirs study on healthy subjects

Lower limb rehabilitation is a fundamental part of post-acute care in neurological disease. Early commencement of active workout is often prevented by paresis, thus physical treatment may be delayed until patients regain some voluntary command of their muscles. Passive mobilization of the affected joints is mostly delivered in order to safeguard tissue properties and shun circulatory problems. The present paper investigates the potential role of early passive motion in stimulating cortical areas of the brain devoted to the control of the lower limb. An electro-mechanical mobilizer for the ankle joint (Toe-Up!) was implemented utilizing specially-designed shape-memory-alloy-based actuators. This device was constructed to be usable by bedridden subjects. Besides, the slowness and gentleness of the imparted motion, make it suitable for patients in a very early stage of their recovery. The mobilizer underwent technical checks to confirm reliability and passed the required safety tests for electric biomedical devices. Four healthy volunteers took part in the pre-clinical phase of the study. The protocol consisted in measuring of brain activity by EEG and NIRS in four different conditions: rest, active dorsiflexion of the ankle, passive mobilization of the ankle, and assisted motion of the same joint. The acquired data were processed to obtain maps of cortical activation, which were then compared. The measurements collected so far show that there is a similar pattern of activity between active and passive/assisted particularly in the contralateral premotor areas. This result, albeit based on very few observations, might suggest that passive motion provides somatosensory afferences that are processed in a similar manner as for voluntary control. Should this evidence be confirmed by further trials on healthy individuals and neurological patients, it could form a basis for a clinical use of early passive exercise in supporting central functional recovery.

A novel biofeedback cycling training to improve gait symmetry in stroke patients: A case series study

The restoration of walking ability is crucial for maximizing independent mobility among patients with stroke. Leg cycling is becoming an established intervention to supplement ambulation training for stroke patients with problems of unbalance and weakness. The aim of the study was to explore the feasibility of a biofeedback pedaling treatment and its effects on cycling and walking ability in chronic stroke patients. Three patients were included in the study. The training consisted of a 2-week treatment of 6 sessions, during which a visual biofeedback helped the participants in maintaining a symmetrical pedaling. Participants were assessed before, after training and at follow-up, by means of a pedaling test and gait analysis. Outcome measurements were the unbalance during pedaling, the temporal, spatial and symmetry parameters during walking. An intra-subject statistical analysis (ANOVA, p<0.05) showed that all patients significantly decreased pedaling unbalance after treatment and maintained the improvements at follow-up. The training induced some gait pattern modifications in two patients: one significantly improved mean velocity and gait symmetry, while the other one reduced the compensation strategy of the healthy leg. The results demonstrated the feasibility of the treatment. If further trials on a larger and controlled scale confirmed the same results, this treatment, thanks to its safety and low price, could have a significant impact as a home-rehabilitation treatment.

VR system for rehabilitation based on hand gestural and olfactory interaction

The study of new systems for supporting upper limb rehabilitation is of primary importance, due to the high number of people in need of rehabilitation and the limited effectiveness of most of the current systems. The research work described in this paper proposes a VR system for upper-limb rehabilitation that is immersive, is based on hand gestures to interact with virtual objects, and which can deliver odours when a goal is reached.

Effective Synchronization of EEG and EMG for Mobile Brain/Body Imaging in Clinical Settings

Mobile Brain/Body Imaging (MoBI) is rapidly gaining traction as a new imaging modality to study how cognitive processes support locomotion. Electroencephalogram (EEG) and electromyogram (EMG), due to their time resolution, non-invasiveness and portability are the techniques of choice for MoBI, but synchronization requirements among others restrict its use to high-end research facilities. Here we test the effectiveness of a technique that enables us to achieve MoBI-grade synchronization of EEG and EMG, even when other strategies (such as Lab Streaming Layer (LSL)) cannot be used e.g., due to the unavailability of proprietary Application Programming Interfaces (APIs), which is often the case in clinical settings. The proposed strategy is that of aligning several spikes at the beginning and end of the session. We delivered a train of spikes to the EEG amplifier and EMG electrodes every 2 s over a 10-min time period. We selected a variable number of spikes (from 1 to 10) both at the beginning and end of the time series and linearly resampled the data so as to align them. We then compared the misalignment of the “middle” spikes over the whole recording to test for jitter and synchronization drifts, highlighting possible nonlinearities (due to hardware filters) and estimated the maximum length of the recording to achieve a [−5 to 5] ms misalignment range. We demonstrate that MoBI-grade synchronization can be achieved within 10-min recordings with a 1.7 ms jitter and [−5 5] ms misalignment range. We show that repeated spike delivery can be used to test online synchronization options and to troubleshoot synchronization issues over EEG and EMG. We also show that synchronization cannot rely only on the equipment sampling rate advertised by manufacturers. The synchronization strategy described can be used virtually in every clinical environment, and may increase the interest among a broader spectrum of clinicians and researchers in the MoBI framework, ultimately leading to a better understanding of the brain processes underlying locomotion control and the development of more effective rehabilitation approaches.