Pesquisador Vinculado
Leonardo Abdala Elias é Professor Associado de Engenharia Biomédica lotado no Departamento de Eletrônica e Engenharia Biomédica (DEEB), Faculdade de Engenharia Elétrica e de Computação (FEEC), Universidade Estadual de Campinas (UNICAMP). Além disso, ele é pesquisador e atual coordenador do Centro de Engenharia Biomédica (CEB), UNICAMP. Fundou e é o atual coordenador do Laboratório de Pesquisa em Neuroengenharia. Sua pesquisa na área de neuroengenharia está focada em investigações teórico-computacionais e experimentais que visam entender como diferentes elementos do sistema neuromusculoesquelético interagem durante o controle do movimento humano em condições normais e patológicas. Dr. Elias se graduou em engenharia elétrica pela Universidade Federal de Goiás (Goiânia, 2008). Recebeu os títulos de mestre e doutor em engenharia biomédica, ambos pela Escola Politécnica da Universidade de São Paulo (São Paulo, 2010 e 2013, respectivamente). Realizou estágio pós-doutoral no Laboratório de Engenharia Biomédica (LEB), Escola Politécnica, Universidade de São Paulo (2013-2015). Foi pesquisador visitante junto ao Department of Neurorehabilitation Engineering, Georg-August University (Göttingen, Alemanha, 2015). Recebeu o título de livre-docente em engenharia biomédica pela Universidade Estadual de Campinas (Campinas, 2022). É membro da International MotoNeuron Society e da Sociedade Brasileira de Engenharia Biomédica.
Neuroengenharia
Neurociência Computacional ➠ Neurofisiologia Humana ➠ Neuromecânica ➠ Processamento de Sinais Neurais ➠ Neurotecnologia ➠ Neuropróteses ➠ Interfaces Neurais

(19) 3521-3756
leoelias@unicamp.br
Biomecânica e Controle Motor
Bioengenharia
Processamento de Sinais Biológicos
Neurociência Computacional
Neurofisiologia do Controle Motor
Neuroengenharia
Neurociência Computacional Aplicada ao Estudo de Doenças Neurodegenerativas
Publicações
2023
Elias, Leonardo Abdala; Hur, Pilwon; Sieck, Gary C
Editorial: Towards an understanding of spinal and corticospinal pathways and mechanisms Miscellaneous
2023, ISSN: 1662-5161.
@misc{pmid37025971,
title = {Editorial: Towards an understanding of spinal and corticospinal pathways and mechanisms},
author = {Leonardo Abdala Elias and Pilwon Hur and Gary C Sieck},
doi = {10.3389/fnhum.2023.1181647},
issn = {1662-5161},
year = {2023},
date = {2023-01-01},
urldate = {2023-01-01},
journal = {Front Hum Neurosci},
volume = {17},
pages = {1181647},
keywords = {},
pubstate = {published},
tppubtype = {misc}
}
2022
Lara, Jéssica Rodrigues; da Silva, Cristiano Rocha; de Lima, Felipe Fava; da Silva, Marcos Camargo; Kohn, André Fabio; Elias, Leonardo Abdala; Magalhães, Fernando Henrique
Effects of light finger touch on the regularity of center-of-pressure fluctuations during quiet bipedal and single-leg postural tasks Journal Article
Em: Gait Posture, vol. 96, pp. 203–209, 2022, ISSN: 1879-2219.
Resumo | Links | BibTeX | Tags:
@article{pmid35696826,
title = {Effects of light finger touch on the regularity of center-of-pressure fluctuations during quiet bipedal and single-leg postural tasks},
author = {Jéssica Rodrigues Lara and Cristiano Rocha da Silva and Felipe Fava de Lima and Marcos Camargo da Silva and André Fabio Kohn and Leonardo Abdala Elias and Fernando Henrique Magalhães},
doi = {10.1016/j.gaitpost.2022.05.036},
issn = {1879-2219},
year = {2022},
date = {2022-07-01},
journal = {Gait Posture},
volume = {96},
pages = {203--209},
abstract = {BACKGROUND: The use of extra sources of sensory information associated with light fingertip touch to enhance postural steadiness has been associated with increased attentional demands, whereas the regularity of center of pressure (COP) fluctuations has been interpreted as a marker of the amount of attention invested in posture control.
RESEARCH QUESTION: This study addressed whether increased attentional demands associated with postural tasks involving light finger touch might be reflected by measures of COP regularity.
METHODS: The experiments involved quiet bipedal stance (n = 8 participants) and single-legged stance (n = 14 participants). Each participant was instructed to stand as quietly as possible on a force plate, either touching an external rigid surface (applied force < 1 N, light touch condition), or not (no touch condition). Postural steadiness was assessed by traditional COP measurements (COP Area, RMS, and velocity), whereas the regularity of postural sway was based on estimates of the sample entropy (SaEn) of the COP time series.
RESULTS: Traditional parameters of postural sway and COP regularity (inversely related to SaEn COP measurements) were reduced during the touch conditions as compared to the no-touch conditions, for both bipedal quiet stance and single-legged stance. Decreased COP regularity with light touch was mainly reflected in the direction of the largest postural sway (i.e. in the sagittal plane for bipedal stance and in the frontal plane for single-legged stance).
SIGNIFICANCE: The present results suggest that actively touching an external surface with the fingertip, besides increasing postural steadiness, generated an externally oriented (presumably cognitive-dependent) focus of attention, so that participants invested less attention on the postural task per se (as suggested by increased SaEn), which might be associated with a more "automatic" control of posture.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
RESEARCH QUESTION: This study addressed whether increased attentional demands associated with postural tasks involving light finger touch might be reflected by measures of COP regularity.
METHODS: The experiments involved quiet bipedal stance (n = 8 participants) and single-legged stance (n = 14 participants). Each participant was instructed to stand as quietly as possible on a force plate, either touching an external rigid surface (applied force < 1 N, light touch condition), or not (no touch condition). Postural steadiness was assessed by traditional COP measurements (COP Area, RMS, and velocity), whereas the regularity of postural sway was based on estimates of the sample entropy (SaEn) of the COP time series.
RESULTS: Traditional parameters of postural sway and COP regularity (inversely related to SaEn COP measurements) were reduced during the touch conditions as compared to the no-touch conditions, for both bipedal quiet stance and single-legged stance. Decreased COP regularity with light touch was mainly reflected in the direction of the largest postural sway (i.e. in the sagittal plane for bipedal stance and in the frontal plane for single-legged stance).
SIGNIFICANCE: The present results suggest that actively touching an external surface with the fingertip, besides increasing postural steadiness, generated an externally oriented (presumably cognitive-dependent) focus of attention, so that participants invested less attention on the postural task per se (as suggested by increased SaEn), which might be associated with a more "automatic" control of posture.
Dideriksen, Jakob; Elias, Leonardo Abdala; Zambalde, Ellen Pereira; Germer, Carina Marconi; Molinari, Ricardo Gonçalves; Negro, Francesco
Influence of central and peripheral motor unit properties on isometric muscle force entropy: A computer simulation study Journal Article
Em: J Biomech, vol. 139, pp. 110866, 2022, ISSN: 1873-2380.
Resumo | Links | BibTeX | Tags:
@article{pmid34802707,
title = {Influence of central and peripheral motor unit properties on isometric muscle force entropy: A computer simulation study},
author = {Jakob Dideriksen and Leonardo Abdala Elias and Ellen Pereira Zambalde and Carina Marconi Germer and Ricardo Gonçalves Molinari and Francesco Negro},
doi = {10.1016/j.jbiomech.2021.110866},
issn = {1873-2380},
year = {2022},
date = {2022-06-01},
journal = {J Biomech},
volume = {139},
pages = {110866},
abstract = {Approximate entropy of isometric force is a popular measure to characterize behavioral changes across muscle contraction conditions. The degree to which force entropy characterizes the randomness of the motor control strategy, however, is not known. In this study, we used a computational model to investigate the correlation between approximate entropy of the synaptic input to a motor neuron pool, the neural drive to muscle (cumulative spike train; CST), and the force. This comparison was made across several simulation conditions, that included different synaptic command signal bandwidths, motor neuron pool sizes, and muscle contractile properties. The results indicated that although force entropy to some degree reflects the entropy of the synaptic command to motor neurons, it is biased by changes in motor unit properties. As a consequence, there was a low correlation between approximate entropy of force and the motor neuron input signal across all simulation conditions (r = 0.13). Therefore, force entropy should only be used to compare motor control strategies across conditions where motor neuron properties can be assumed to be maintained. Instead, we recommend that the entropy of the descending motor commands should be estimated from CSTs comprising spike trains of multiple motor units.},
keywords = {},
pubstate = {published},
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Ribeiro, Rebecca Fernandes; Frencl, Victor Baptista; Elias, Leonardo Abdala; do Val, João Bosco Ribeiro
A Case Study on the Removal of Blinking Artifact in Electroencephalogram Signals via Stochastic Filtering Journal Article
Em: Journal of Control, Automation and Electrical Systems, vol. 33, pp. 1319–1328, 2022.
Resumo | Links | BibTeX | Tags:
@article{nokey,
title = {A Case Study on the Removal of Blinking Artifact in Electroencephalogram Signals via Stochastic Filtering},
author = {Rebecca Fernandes Ribeiro and Victor Baptista Frencl and Leonardo Abdala Elias and João Bosco Ribeiro do Val },
doi = {https://doi.org/10.1007/s40313-021-00890-y},
year = {2022},
date = {2022-01-12},
journal = {Journal of Control, Automation and Electrical Systems},
volume = {33},
pages = {1319–1328},
abstract = {The presence of physiological artifacts in electroencephalogram (EEG) signals is common and detrimental to experimental or clinical analysis. This paper presents a case study where we develop an algorithm based on stochastic filtering to remove blinking artifacts. For this case study, the dynamic system was defined by combining two autoregressive models, the first one represents the EEG signal, and the second one represents the blinking artifact. Some applications use stochastic methods to remove artifacts, so in this paper we apply the stochastic filtering via Kalman filter, that makes possible to remove blinking artifacts from single-channel EEG recordings, as long as the electrooculogram (EOG) signal was available. The method applies to a case study with actual artifacts and simulated artifacts for comparison. The measure of performance utilized is the estimated power spectral density (PSD). The results show that the proposed method could remove blinking artifacts without introducing significant distortions in the EEG signal.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Stanisic, Danijela; Cruz, Guilherme C F; Elias, Leonardo Abdala; Tsukamoto, Junko; Arns, Clarice W; da Silva, Douglas Soares; Mochkalev, Stanislav; Savu, Raluca; Tasic, Ljubica
Em: Front Bioeng Biotechnol, vol. 10, pp. 858156, 2022, ISSN: 2296-4185.
Resumo | Links | BibTeX | Tags:
@article{pmid35646854,
title = {High-Resolution Magic-Angle Spinning NMR Spectroscopy for Evaluation of Cell Shielding by Virucidal Composites Based on Biogenic Silver Nanoparticles, Flexible Cellulose Nanofibers and Graphene Oxide},
author = {Danijela Stanisic and Guilherme C F Cruz and Leonardo Abdala Elias and Junko Tsukamoto and Clarice W Arns and Douglas Soares da Silva and Stanislav Mochkalev and Raluca Savu and Ljubica Tasic},
doi = {10.3389/fbioe.2022.858156},
issn = {2296-4185},
year = {2022},
date = {2022-01-01},
urldate = {2022-01-01},
journal = {Front Bioeng Biotechnol},
volume = {10},
pages = {858156},
abstract = {Antiviral and non-toxic effects of silver nanoparticles onto cells infected with coronavirus were evaluated in this study using High-Resolution Magic-Angle Spinning Nuclear Magnetic Resonance (HR-MAS NMR) spectroscopy. Silver nanoparticles were designed and synthesized using an orange flavonoid-hesperetin (HST)-for reduction of silver(I) and stabilization of as obtained nanoparticles. The bio-inspired process is a simple, clean, and sustainable way to synthesize biogenic silver nanoparticles (AgNP@HST) with diameters of ∼20 nm and low zeta potential (-40 mV), with great colloidal stability monitored for 2 years. The nanoparticles were used for the fabrication of two types of antiviral materials: colloids (AgNP@HST spray) and 3D flexible nanostructured composites. The composites, decorated with AgNP@HST (0.05 mmol L), were made using cellulose nanofibers (CNF) obtained from orange peel and graphene oxide (GO), being denominated CNF@GO@AgNP@HST. Both materials showed high virucidal activity against coronaviruses in cell infection models and successfully inhibited the viral activity in cells. HR-MAS H-NMR technique was used for determining nanomaterials' effects on living cells and their influences on metabolic pathways, as well as to study viral effects on cells. It was proven that none of the manufactured materials showed toxicity towards the intact cells used. Furthermore, viral infection was reverted when cells, infected with the coronavirus, were treated using the as-fabricated nanomaterials. These significant results open possibilities for antiviral application of 3D flexible nanostructured composite such as packaging papers and filters for facial masks, while the colloidal AgNP@HST spray can be used for disinfecting surfaces, as well as a nasal, mouth, and eye spray.},
keywords = {},
pubstate = {published},
tppubtype = {article}
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Batista-Ferreira, Leandra; Rabelo, Natielle Ferreira; da Cruz, Gabriel Menezes; de Almeida Costa, Juliana Nunes; Elias, Leonardo Abdala; Mezzarane, Rinaldo André
Effects of voluntary contraction on the soleus H-reflex of different amplitudes in healthy young adults and in the elderly Journal Article
Em: Front Hum Neurosci, vol. 16, pp. 1039242, 2022, ISSN: 1662-5161.
Resumo | Links | BibTeX | Tags:
@article{pmid36590063,
title = {Effects of voluntary contraction on the soleus H-reflex of different amplitudes in healthy young adults and in the elderly},
author = {Leandra Batista-Ferreira and Natielle Ferreira Rabelo and Gabriel Menezes da Cruz and Juliana Nunes de Almeida Costa and Leonardo Abdala Elias and Rinaldo André Mezzarane},
doi = {10.3389/fnhum.2022.1039242},
issn = {1662-5161},
year = {2022},
date = {2022-01-01},
urldate = {2022-01-01},
journal = {Front Hum Neurosci},
volume = {16},
pages = {1039242},
abstract = {A number of H-reflex studies used a moderate steady voluntary contraction in an attempt to keep the motoneuron pool excitability relatively constant. However, it is not clear whether the voluntary muscle activation itself represents a confounding factor for the elderly, as a few ongoing mechanisms of reflex modulation might be compromised. Further, it is well-known that the amount of either inhibition or facilitation from a given conditioning depends on the size of the test H-reflex. The present study aimed at evaluating the effects of voluntary contraction over a wide range of reflex amplitudes. A significant reflex facilitation during an isometric voluntary contraction of the soleus muscle (15% of the maximal voluntary isometric contraction-MVC) was found for both young adults and the elderly ( < 0.05), regardless of their test reflex amplitudes (considering the ascending limb of the H-reflex recruitment curve-RC). No significant difference was detected in the level of reflex facilitation between groups for all the amplitude parameters extracted from the RC. Simulations with a computational model of the motoneuron pool driven by stationary descending commands yielded qualitatively similar amount of reflex facilitation, as compared to human experiments. Both the experimental and modeling results suggest that possible age-related differences in spinal cord mechanisms do not significantly influence the reflex modulation during a moderate voluntary muscle activation. Therefore, a background voluntary contraction of the ankle extensors (e.g., similar to the one necessary to maintain upright stance) can be used in experiments designed to compare the RCs of both populations. Finally, in an attempt to elucidate the controversy around changes in the direct motor response (M-wave) during contraction, the maximum M-wave (Mmax) was compared between groups and conditions. It was found that the Mmax significantly increases ( < 0.05) during contraction and decreases ( < 0.05) with age arguably due to muscle fiber shortening and motoneuron loss, respectively.},
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}