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19 results on '"Rigoni, Isotta"'

1. Tensions between Preference and Performance: Designing for Visual Exploration of Multi-frequency Medical Network Data

Author

Knoll, Christian, Koesten, Laura, Rigoni, Isotta, Vulliémoz, Serge, and Möller, Torsten

Subjects
Computer Science - Human-Computer Interaction
Abstract

The analysis of complex high-dimensional data is a common task in many domains, resulting in bespoke visual exploration tools. Expectations and practices of domain experts as users do not always align with visualization theory. In this paper, we report on a design study in the medical domain where we developed two high-fidelity prototypes encoding EEG-derived brain network data with different types of visualizations. We evaluate these prototypes regarding effectiveness, efficiency, and preference with two groups: participants with domain knowledge (domain experts in medical research) and those without domain knowledge, both groups having little or no visualization experience. A requirement analysis and study of low-fidelity prototypes revealed a strong preference for a novel and aesthetically pleasing visualization design, as opposed to a design that is considered more optimal based on visualization theory. Our study highlights the pros and cons of both approaches, discussing trade-offs between task-specific measurements and subjective preference. While the aesthetically pleasing and novel low-fidelity prototype was favored, the results of our evaluation show that, in most cases, this was not reflected in participants' performance or subjective preference for the high-fidelity prototypes., Comment: 13 pages, 4 figures, 2 tables

Published
2024

4. Muscle stimulation via whole body vibration for postural control applications

Author

Rigoni, Isotta

Subjects
612
Abstract

Although the ability to balance might feel effortless to the most, it should not be given for granted as even the normal process of ageing can compromise it, jeopardising people physical independence. It is therefore important to implement safe training routines that ultimately improve postural control strategies. We evaluated the suitability of whole body vibration (WBV) training -which induces muscle contraction via the stimulation of muscle spindles - for postural control applications. First, we tested the efficacy of different combinations of stimulation frequency and subjects' posture in eliciting a response from those muscles that play a key role for the implementation of postural responses. Each combination was evaluated by jointly measuring the resulting muscular activation and soft-tissue displacement. Then, we investigated how the selected WBV stimulation affected the balance of healthy subjects. We evaluated the latter by analysing centre of pressure trajectories, muscle and cortex activation and their respective interplay. We found that high frequency vibrations, delivered to participants standing on their forefeet, evoked the greatest contraction of the plantarflexors. Undisturbed balance recorded after such stimulation was characterised by an increased sensitivity of muscle spindles. In line with the latter, the communication between the periphery and the central nervous system (CNS) increased after the stimulation and different muscle recruitment patterns were employed to maintain balance. On the posturography side, stability was found to be compromised in the acute term but seemed to have recovered over a longer term. Together, these findings suggest that, if appropriately delivered, WBV has the potential to stimulate the spindles of the plantarflexors. By doing so, vibration training seems to be able to augment the communication between the proprioceptive organs and the CNS, on which the system relies to detect and react to perturbations, leading to sensorimotor recalibration.

Published
2021
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8. Involvement of the contralateral hippocampus in ictal‐like but not interictal epileptic activities in the kainate mouse model of temporal lobe epilepsy.

Author

Padmasola, Guru Prasad, Friscourt, Fabien, Rigoni, Isotta, Vulliémoz, Serge, Schaller, Karl, Michel, Christoph M., Sheybani, Laurent, and Quairiaux, Charles

Subjects
TEMPORAL lobe epilepsy, LABORATORY mice, PEOPLE with epilepsy, ANIMAL disease models, HIPPOCAMPUS (Brain)
Abstract

Objective: Animal and human studies have shown that the seizure‐generating region is vastly dependent on distant neuronal hubs that can decrease duration and propagation of ongoing seizures. However, we still lack a comprehensive understanding of the impact of distant brain areas on specific interictal and ictal epileptic activities (e.g., isolated spikes, spike trains, seizures). Such knowledge is critically needed, because all kinds of epileptic activities are not equivalent in terms of clinical expression and impact on the progression of the disease. Methods: We used surface high‐density electroencephalography and multisite intracortical recordings, combined with pharmacological silencing of specific brain regions in the well‐known kainate mouse model of temporal lobe epilepsy. We tested the impact of selective regional silencing on the generation of epileptic activities within a continuum ranging from very transient to more sustained and long‐lasting discharges reminiscent of seizures. Results: Silencing the contralateral hippocampus completely suppresses sustained ictal activities in the focus, as efficiently as silencing the focus itself, but whereas focus silencing abolishes all focus activities, contralateral silencing fails to control transient spikes. In parallel, we observed that sustained focus epileptiform discharges in the focus are preceded by contralateral firing and more strongly phase‐locked to bihippocampal delta/theta oscillations than transient spiking activities, reinforcing the presumed dominant role of the contralateral hippocampus in promoting long‐lasting, but not transient, epileptic activities. Significance: Altogether, our work provides suggestive evidence that the contralateral hippocampus is necessary for the interictal to ictal state transition and proposes that crosstalk between contralateral neuronal activity and ipsilateral delta/theta oscillation could be a candidate mechanism underlying the progression from short‐ to long‐lasting epileptic activities. [ABSTRACT FROM AUTHOR]

Published
2024
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15. Cortical Pathways During Postural Control: new insights from functional EEG source connectivity

Author

Barollo, Fabio, Hassan, Mahmoud, Petersen, Hannes, Rigoni, Isotta, Ramon, Ceon, Gargiulo, Paolo, Fratini, Antonio, Barollo, Fabio, Hassan, Mahmoud, Petersen, Hannes, Rigoni, Isotta, Ramon, Ceon, Gargiulo, Paolo, and Fratini, Antonio

Abstract

Postural control is a complex feedback system that relies on vast array of sensory inputs in order to maintain a stable upright stance. The brain cortex plays a crucial role in the processing of this information and in the elaboration of a successful adaptive strategy to external stimulation preventing loss of balance and falls. In the present work, the participants postural control system was challenged by disrupting the upright stance via a mechanical skeletal muscle vibration applied to the calves. The EEG source connectivity method was used to investigate the cortical response to the external stimulation and highlight the brain network primarily involved in high-level coordination of the postural control system. The cortical network reconfiguration was assessed during two experimental conditions of eyes open and eyes closed and the network flexibility (i.e. its dynamic reconfiguration over time) was correlated with the sample entropy of the stabilogram sway. The results highlight two different cortical strategies in the alpha band: the predominance of frontal lobe connections during open eyes and the strengthening of temporal-parietal network connections in the absence of visual cues. Furthermore, a high correlation emerges between the flexibility in the regions surrounding the right temporo-parietal junction and the sample entropy of the CoP sway, suggesting their centrality in the postural control system. These results open the possibility to employ network-based flexibility metrics as markers of a healthy postural control system, with implications in the diagnosis and treatment of postural impairing diseases.

Published
2022

19. FE-Modelling and Material Characterization of Ice-Hockey Helmet

Author

Rigoni, Isotta

Subjects
Medical Engineering, traumatic brain injury, ice-hockey, helmet, finite element, Medicinteknik
Abstract

The aim of this research was to produce a reliable finite element model of a helmet, that could be used to simulate approval tests as well as impacts to investigate the safety offered. A 2D and 3D mesh was generated from the CAD file of an Easton Synergy 380 with HyperWorks, and then checked referring to standard parameter values. A few specimens cut from the liner were tested with the Instron Electropuls E3000 (Instron, High Wycombe, Great Britain) machine to determine Young’s modulus, Poisson’s ratio and the density of the EPP. The numerical model was characterised with appropriate materials with Ls-PrePost, such as ABS for the shell, EPP for the liner and steel for the impact anvil. The foam was implemented both with the *063_CRUSHABLE_FOAM and the *126_MODIFIED_HONEYCOMB card, in two different configurations. The helmet model was coupled with a finite element model of a HIII head form and three impact scenarios were set up. Backward, lateral and pitched impact were simulated and results were compared with those obtained from the experimental tests carried on at the MIPS. The two configurations were tested in all the three scenarios. The correlation between numerical and experimental results was evaluated by analysing the linear and rotational acceleration, and the rotational velocity, recorded by the accelerometer positioned inside the HIII headform. The parameters used were the Pearson correlation coefficient, the peak linear acceleration score, the shape of the curves, the time occurrence of peaks and the percentage of the difference between them. The first configuration showed good correlation scores (>85%) for the backward and lateral impact, for the rotational velocity and acceleration, while lower values were recorded for the pitched impact simulation. Lower values (70.88% and 77.76%) were obtained for the peak linear acceleration score, which stress the need for modifications of the contact definition in Ls-PrePost or a more detailed material testing. Worse results were recorded for the second configuration, but the smaller computational time required suggests that more attempts should be done in this direction.

Published
2017

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