Modeling foot sole cutaneous afferents: FootSim

Katic, Natalija; Siqueira, Rodrigo Kazu; Cleland, Luke D; Strzalkowski, Nicholas D. J.; Bent, Leah R.; Raspopović, Staniša; Saal, Hannes P.

doi:10.1016/j.isci.2022.105874

Cited by 15 publications

(16 citation statements)

References 51 publications

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“…Finally, the large range of possible pressure values (from light contact to forces exceeding body weight several fold) necessitate neural mechanisms that are robust over this range. Recently, computational models have been developed that allow simulation of tactile neural responses from the foot and which will help study the nature of tactile feedback in more depth than possible at the moment (27).…”

Section: Discussionmentioning

confidence: 99%

Complexity of spatiotemporal plantar pressure patterns during everyday behaviours

Cleland

Rowland

Mazzà

et al. 2023

Preprint

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The human foot sole is the primary interface with the external world during balance and walking, and also provides important tactile information on the state of contact. However, prior stud- ies on plantar pressure have focused mostly on summary metrics such as overall force or centre of pressure under limited condi- tions. Here, we recorded spatiotemporal plantar pressure pat- terns with high spatial resolution while participants completed a wide range of daily activities, including balancing, locomotion, and jumping tasks. Contact area differed across task categories, but was only moderately correlated with the overall force expe- rienced by the foot sole. The centre of pressure was often located outside the contact area or in locations experiencing relatively low pressure, and therefore a result of disparate contact regions spread widely across the foot. Non-negative matrix factorisation revealed low-dimensional spatial complexity that increased dur- ing interaction with unstable surfaces. Additionally, pressure patterns at the heel and metatarsals decomposed into separately located and robustly identifiable components, jointly capturing most variance in the signal. These results suggest optimal sen- sor placements to capture task-relevant spatial information and provide insight into how pressure varies spatially on the foot sole during a wide variety of natural behaviours.

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Section: Discussionmentioning

confidence: 99%

Complexity of spatiotemporal plantar pressure patterns during everyday behaviours

Cleland

Rowland

Mazzà

et al. 2023

Preprint

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“…We used the computational model of foot sole cutaneous afferents (FootSim) 48 to design new biomimetic stimulation strategies. Environment is modeled as a single, or continuous mechanical stimuli.…”

Section: Resultsmentioning

confidence: 99%

“…Using this multifaceted approach, we are exploiting the architecture established by the development of validated model-based neurotechnology in human applications. More in detail, we first designed biomimetic neurostimulation strategies to restore somatosensory feedback by exploiting a realistic in-silico model of human afferents behavior (FootSim) 48 . This computational model can emulate the neural activity of the sensory afferents, innervating the plantar area of the human foot, in response to spatio-temporal skin deformations.…”

Section: Introductionmentioning

confidence: 99%

Biomimetic computer-to-brain communication restoring naturalistic touch sensations via peripheral nerve stimulation

Valle

Katic

Eggemann

et al. 2023

Preprint

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Artificial communication with the brain through peripheral nerve stimulation recently showed promising results in people with sensorimotor deficits. However, these efforts fall short in delivering close-to-natural rich sensory experience, resulting in the necessity to propose novel venues for converting sensory information into neural stimulation patterns, which would possibly enable intuitive and natural sensations. To this aim, we designed and tested a biomimetic neurostimulation framework inspired by nature, able 'to write' physiologically plausible information back into the residual healthy nervous system. Starting from the in-silico model of mechanoreceptors, we designed biomimetic policies of stimulation, emulating the activity of different afferent units. Then, we experimentally assessed these novel paradigms, alongside mechanical touch and commonly used, linear neuromodulations. We explored the somatosensory neuroaxis by stimulating the nerve while recording the neural responses at the dorsal root ganglion and spinal cord of decerebrated cats. Biomimetic stimulation resulted in a neural activity that travels consistently along the neuroaxis, producing the spatio-temporal neural dynamic more like the naturally evoked one. Finally, we then implemented these paradigms within the bionic device and tested it with patients. Biomimetic neurostimulations resulted in higher mobility and decreased mental effort compared to traditional approaches. The results of this neuroscience-driven technology inspired by the human body could be a model for the development of novel assistive neurotechnologies.

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“…The aim of the study was to evaluate the possible benefits of non-linear multiparameter modulation (PW and PF), inspired from invasive approaches [11,19,41,54], and recent modelling [64], on the naturalness, intuitiveness and functional usability, of the TENS-elicited sensations. To this aim, it was firstly necessary to ensure reliable and robust comparison across paradigms, by avoiding design biases such as differences in the perceived intensity.…”

Section: Q1 Can Multiparametric Tens Modulations Improvementioning

confidence: 99%

“…Indeed, it modulated PF according to the biomimetic firing rate profile (biomimetic PF), extracted using a realistic in-silico model of foot cutaneous afferents. The model, called FootSim [64] emulates the response of all the cutaneous afferents innervating the foot sole to any type of mechanical skin deformation. It allows to populate the virtual foot sole with some or all the tactile afferents classes, to choose the features (location, duration, contact force profile) of the mechanical stimulus applied on the foot sole and then to export the related temporal and spatial afferent fibers activation.…”

Section: Sensory Encoding Strategies Designmentioning

confidence: 99%

Multiparametric non-linear TENS modulation to integrate intuitive sensory feedback

Bucciarelli,

Gozzi,

Katic

et al. 2023

J. Neural Eng.

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Objective. Transcutaneous Electrical Nerve Stimulation (TENS) has been recently introduced in neurorehabilitation and neuroprosthetics as a promising, non-invasive sensory feedback restoration alternative to implantable neurostimulation. Yet, the adopted stimulation paradigms are typically based on single-parameter modulations (e.g., pulse amplitude PA, pulse-width PW or pulse frequency PF). They elicit artificial sensations characterized by a low intensity resolution (e.g., few perceived levels), low naturalness and intuitiveness, hindering the acceptance of this technology. To address these issues, we designed novel multiparametric stimulation paradigms, featuring the simultaneous modulation of multiple parameters, and implemented them in real-time tests of performance when exploited as artificial sensory inputs. Approach. We initially investigated the contribution of PW and PF variations to the perceived sensation magnitude through discrimination tests. Then, we designed three multiparametric stimulation paradigms comparing them with a standard PW linear modulation in terms of evoked sensation naturalness and intensity. The most performant paradigms were then implemented in real-time in a Virtual Reality - TENS platform to assess their ability to provide intuitive somatosensory feedback in a functional task. Main results. Our study highlighted a strong negative correlation between perceived naturalness and intensity: less intense sensations are usually deemed as more like natural touch. In addition, we observed that PF and PW changes have a different weight on the perceived sensation intensity. As a result, we adapted the Activation Charge Rate (ACR) equation, proposed for implantable neurostimulation to predict the perceived intensity while co-modulating the PF and charge per pulse, to TENS (ACRT). ACRT allowed to design different multiparametric TENS paradigms with the same absolute perceived intensity. Although not reported as more natural, the multiparametric paradigm, based on sinusoidal PF modulation, resulted being more intuitive and subconsciously integrated than the standard linear one. This allowed subjects to achieve a faster and more accurate functional performance. Significance. Our findings suggest that TENS-based, multiparametric neurostimulation, despite not consciously perceived naturally, can provide integrated and more intuitive somatosensory information, as functionally proved. This could be exploited to design novel encoding strategies able to improve the performance of non-invasive sensory feedback technologies.

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Modeling foot sole cutaneous afferents: FootSim

Cited by 15 publications

References 51 publications

Complexity of spatiotemporal plantar pressure patterns during everyday behaviours

Complexity of spatiotemporal plantar pressure patterns during everyday behaviours

Biomimetic computer-to-brain communication restoring naturalistic touch sensations via peripheral nerve stimulation

Multiparametric non-linear TENS modulation to integrate intuitive sensory feedback

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